WO2023102865A1 - Broadband image apparatus and method of fabricating the same - Google Patents

Broadband image apparatus and method of fabricating the same Download PDF

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Publication number
WO2023102865A1
WO2023102865A1 PCT/CN2021/136926 CN2021136926W WO2023102865A1 WO 2023102865 A1 WO2023102865 A1 WO 2023102865A1 CN 2021136926 W CN2021136926 W CN 2021136926W WO 2023102865 A1 WO2023102865 A1 WO 2023102865A1
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Prior art keywords
electromagnetic wave
conversion element
wave conversion
dti
image apparatus
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PCT/CN2021/136926
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French (fr)
Inventor
Seiji Takahashi
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Huawei Technologies Co., Ltd.
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Priority to CN202180096512.0A priority Critical patent/CN117178367A/en
Priority to PCT/CN2021/136926 priority patent/WO2023102865A1/en
Publication of WO2023102865A1 publication Critical patent/WO2023102865A1/en

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L27/00—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate
    • H01L27/14—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate including semiconductor components sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation
    • H01L27/144—Devices controlled by radiation
    • H01L27/146—Imager structures
    • H01L27/14601—Structural or functional details thereof
    • H01L27/1464—Back illuminated imager structures
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L27/00—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate
    • H01L27/14—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate including semiconductor components sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation
    • H01L27/144—Devices controlled by radiation
    • H01L27/146—Imager structures
    • H01L27/14601—Structural or functional details thereof
    • H01L27/14609—Pixel-elements with integrated switching, control, storage or amplification elements
    • H01L27/1461—Pixel-elements with integrated switching, control, storage or amplification elements characterised by the photosensitive area
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L27/00—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate
    • H01L27/14—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate including semiconductor components sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation
    • H01L27/144—Devices controlled by radiation
    • H01L27/146—Imager structures
    • H01L27/14601—Structural or functional details thereof
    • H01L27/14609—Pixel-elements with integrated switching, control, storage or amplification elements
    • H01L27/14612—Pixel-elements with integrated switching, control, storage or amplification elements involving a transistor
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L27/00—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate
    • H01L27/14—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate including semiconductor components sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation
    • H01L27/144—Devices controlled by radiation
    • H01L27/146—Imager structures
    • H01L27/14601—Structural or functional details thereof
    • H01L27/14625—Optical elements or arrangements associated with the device
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L27/00—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate
    • H01L27/14—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate including semiconductor components sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation
    • H01L27/144—Devices controlled by radiation
    • H01L27/146—Imager structures
    • H01L27/14601—Structural or functional details thereof
    • H01L27/14625—Optical elements or arrangements associated with the device
    • H01L27/14629—Reflectors
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L27/00—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate
    • H01L27/14—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate including semiconductor components sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation
    • H01L27/144—Devices controlled by radiation
    • H01L27/146—Imager structures
    • H01L27/14601—Structural or functional details thereof
    • H01L27/1463—Pixel isolation structures
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L27/00—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate
    • H01L27/14—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate including semiconductor components sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation
    • H01L27/144—Devices controlled by radiation
    • H01L27/146—Imager structures
    • H01L27/14643—Photodiode arrays; MOS imagers
    • H01L27/14649—Infrared imagers
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L27/00—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate
    • H01L27/14—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate including semiconductor components sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation
    • H01L27/144—Devices controlled by radiation
    • H01L27/146—Imager structures
    • H01L27/14601—Structural or functional details thereof
    • H01L27/14603—Special geometry or disposition of pixel-elements, address-lines or gate-electrodes
    • H01L27/14605—Structural or functional details relating to the position of the pixel elements, e.g. smaller pixel elements in the center of the imager compared to pixel elements at the periphery
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L27/00—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate
    • H01L27/14—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate including semiconductor components sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation
    • H01L27/144—Devices controlled by radiation
    • H01L27/146—Imager structures
    • H01L27/14601—Structural or functional details thereof
    • H01L27/1462—Coatings
    • H01L27/14623—Optical shielding
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L27/00—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate
    • H01L27/14—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate including semiconductor components sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation
    • H01L27/144—Devices controlled by radiation
    • H01L27/146—Imager structures
    • H01L27/14601—Structural or functional details thereof
    • H01L27/14625—Optical elements or arrangements associated with the device
    • H01L27/14627—Microlenses

Definitions

  • the present invention relates to an image apparatus and a method of fabrication thereof. More specifically, the present invention relates to a broadband radiation sensitive structure having at least two different materials and a method of fabrication thereof.
  • SWIR short wave infrared
  • Silicon used for conventional solid-state imaging devices has a large energy bandgap and therefore has a difficulty in detecting light having a wavelength in the SWIR spectrum range. Therefore, imaging devices operating in the SWIR spectrum range can be realized by utilizing a semiconductor material having a bandgap smaller than that of Si.
  • a semiconductor material having a bandgap smaller than that of Si may be prepared by a process using a single crystal bulk wafer which is different from an Si device wafer, or by depositing the material on a wafer having Si devices with selective epitaxial growth.
  • United States Patent No. 10, 991, 745 proposes a device 2300 using an InGaAs material for a photosensitive layer as shown in Figure 23.
  • An InGaAs layer 2304 is formed on a wafer or a chip 2302 by, for example, the epitaxial growth.
  • the wafer or chip 2302 having the InGaAs layer 2304 is bonded between a different substrate 2306 on which a silicon pixel layer 2308 has been formed, and a further different substrate 2310 on which logic devices 2312 have been formed.
  • such a device using an InGaAs layer has extremely large and thick InGaAs layer as a photosensitive layer, which results in high cost.
  • the InGaAs process is not compatible with a conventional CMOS-based process. Therefore, such a device requires a complicated process as described above. As a result, the application is limited.
  • United States Patent No. 9, 954, 016 proposes a device 2400 employing a GeSi layer 2402 as a photosensitive layer, of which process is CMOS based as shown in Figure 24.
  • CMOS complementary metal-oxide-semiconductor
  • an area of the GeSi layer as the photosensitive layer is significantly large. Since a dark current, which is a source of a noise, is proportional to the area of the GeSi layer, the dark current becomes very high. Such a large dark current has a large adverse impact on a signal-noise ratio (SNR) and a dynamic range (DR) .
  • SNR signal-noise ratio
  • DR dynamic range
  • United States Patent No. 11,063,079 proposes a device 2500 having a Ge layer 2504 as a photosensitive layer located on a top of a Si layer 2502 having a pyramid shape as shown in Figure 25.
  • the Si layer 2502 is configured to direct light to the small Ge layer 2504.
  • such a structure is significantly different from a conventional CMOS imaging sensor structure, and thus it is difficult to implement a pixel device.
  • the Ge layer 2504 is directly formed on the Si layer 2502. Therefore, the device 2500 has a large dislocation density resulting from a difference between the lattice constants of Si and Ge, and causing a high dark current.
  • a solid-state imaging device which is compatible with conventional CMOS process that has a small dark current and that can detect light having a range of a SWIR spectrum, is desired.
  • a first embodiment according to the present invention provides an image apparatus, comprising:
  • a substrate having a first surface, on which an electromagnetic wave impinges and a second surface opposite to the first surface;
  • a first electromagnetic wave conversion element formed in the substrate and composed of a first material having a first bandgap
  • a second electromagnetic wave conversion element on a side of the second surface and composed of a second material having a second bandgap different from the first band gap such that the second electromagnetic wave conversion element overlaps the first electromagnetic wave conversion element in a plan view;
  • DTI deep trench isolation
  • the electromagnetic wave can be detected with wide dynamic range.
  • the image apparatus may further comprise a buffer layer disposed between the first electromagnetic wave conversion element and the second electromagnetic wave conversion element and the buffer layer comprises the first material and the second material.
  • the buffer layer may reduce the lattice mismatch to reduce or avoid dislocation defect.
  • the buffer layer may be configured such that, closer to the second electromagnetic wave conversion element, a concentration of the second material is higher.
  • the buffer layer may reduce the lattice mismatch to reduce or avoid dislocation defect.
  • the image apparatus may further comprise a buffer layer disposed between the first electromagnetic wave conversion element and the second electromagnetic wave conversion element and including the second material, and
  • a doping concentration of the buffer layer may be configured to be higher.
  • the buffer layer may reduce the lattice mismatch to reduce or avoid dislocation defect.
  • the first material may be silicon
  • the second material may be selected from the group consisting of SiGe, germanium, InGaAs, GaAs, a III-V material, quantum dots, an organic material, an inorganic material, or other radiation sensitive material, or combinations thereof.
  • electromagnetic wave can be detected with wide dynamic range.
  • the first DTI may be configured to reflect electromagnetic wave impinging the image apparatus to condense the electromagnetic wave to the second electromagnetic wave conversion element.
  • the detection efficiency is improved.
  • the first DTI may be disposed on a periphery of the image apparatus in a plan view.
  • the first DTI directs the electromagnetic wave to the second electromagnetic wave conversion element and functions as a device isolation.
  • the first DTI may be disposed inward of the periphery of the image apparatus in a plan view.
  • the first DTI directs the electromagnetic wave to the second electromagnetic wave conversion element at a higher efficiency.
  • the image apparatus may further comprise a second DTI extending in the substrate from the first surface toward the second surface and at least partially surrounding the first DTI.
  • the depth of the first DTI may be less than the thickness of the substrate.
  • the depth of the first DTI may be equal to the thickness of the substrate.
  • the depth of the second DTI may be less than the thickness of the substrate.
  • the depth of the second DTI may be equal to the thickness of the substrate.
  • the thickness of the first DTI in a plan view may be greater than the thickness of the second DTI in a plan view.
  • the thickness of the first DTI in a plan view may be less than the thickness of the second DTI in a plan view.
  • the first electromagnetic wave conversion element may have a polygonal shape in a plan view
  • the first DTI may be disposed on at least a part of at least two sides of the first electromagnetic wave conversion element in a plan view.
  • a footprint of the first DTI is reduced, and leads to miniaturization of the device.
  • the first DTI may at least partially surround the first electromagnetic wave conversion element
  • a part of the second DTI may at least partially surround the first electromagnetic wave conversion element.
  • the image apparatus may further comprise a light-condensing element configured to condense electromagnetic wave impinging the first surface to the second electromagnetic wave conversion element.
  • the light-condensing element may be at least one recess disposed on the first surface.
  • the light-condensing element may be a tapered portion of the first DTI disposed on the second surface such that, closer to the second surface, the thickness in a plan view may be larger toward the second electromagnetic wave conversion element.
  • the light-condensing element may be a shallow trench isolation (STI) disposed inside of the first DTI in a plan view and at least partially surrounding the second electromagnetic wave conversion element.
  • STI shallow trench isolation
  • the light-condensing element may be a light-shielding layer comprising an aperture overlapping with the first electromagnetic wave conversion element.
  • the light-condensing element may be a lens disposed on the first surface.
  • the light-condensing element may be a metal layer disposed on the second surface and at least partially surrounding the second electromagnetic wave conversion element.
  • an insulation film may be disposed on the second surface
  • the light-condensing element may be a metal layer in the insulation film such that the metal layer may overlap the second electromagnetic wave conversion element in a plan view.
  • the light-condensing element may further comprise a metal layer in the insulation film such that the metal layer may at least partially surround the second electromagnetic wave conversion element in a plan view.
  • the metal layer at least partially surrounding the second electromagnetic wave conversion element may electrically couple to the first electromagnetic wave conversion element by contacts
  • the contacts may at least partially surround the second electromagnetic wave conversion element.
  • the electromagnetic wave is reflected on the metal layer toward the second electromagnetic wave conversion element to improve the light conversion efficiency.
  • the metal layer overlapping the second electromagnetic wave conversion element may electrically couple to the metal layer at least partially surrounding the second electromagnetic wave conversion element by vias, and
  • the vias may at least partially surround the second electromagnetic wave conversion element.
  • the electromagnetic wave is reflected on the metal layer toward the second electromagnetic wave conversion element to improve the light conversion efficiency.
  • the light-condensing element may be a silicidation layer disposed on outer surfaces of the second electromagnetic wave conversion layer.
  • the electromagnetic wave is reflected on the silicidation layer toward the second electromagnetic wave conversion element to improve the light conversion efficiency.
  • the image apparatus may further comprise at least one third electromagnetic wave conversion element disposed in the substrate and at least partially between the first DTI and the second DTI, the third electromagnetic wave conversion element being composed of the first material having the first band gap.
  • a volume of the electromagnetic wave conversion elements can be substantially increased and leads to an increase of the full-well capacity.
  • the first electromagnetic wave conversion element may be coupled to the third electromagnetic wave conversion element.
  • the first electromagnetic wave conversion element and the third electromagnetic wave conversion element may be coupled to different charge transfer gates disposed on the second surface, respectively.
  • the first electromagnetic wave conversion element and the third electromagnetic wave conversion element may be coupled to one common charge transfer gate disposed on the second surface.
  • the first electromagnetic wave conversion element may be coupled to a charge transfer gate disposed on the second surface, and
  • the charge transfer gate may extend into the substrate.
  • the image apparatus may further comprise a bias electrode electrically coupled to the second electromagnetic wave conversion element and configured to apply a bias voltage to the second electromagnetic wave conversion element.
  • a bias voltage can be applied to the second electromagnetic wave conversion element to substantially increase a full-well capacity and improve dynamic range.
  • the image apparatus may further comprise:
  • bias electrode in the insulation film, the bias electrode overlapping the second electromagnetic wave conversion element in a plan view, and separated from the second electromagnetic wave conversion element.
  • a bias voltage can be applied to the second electromagnetic wave conversion element to substantially increase a full-well capacity and improve dynamic range.
  • the image apparatus may further comprise a fixed charge film at least partially covering the second surface and the second electromagnetic wave conversion element.
  • a bias voltage can be applied to the second electromagnetic wave conversion element to substantially increase a full-well capacity and improve dynamic range.
  • the image apparatus may further comprise an intrinsic stress film at least partially covering the second surface and the second electromagnetic wave conversion element.
  • a stress can be applied to the second electromagnetic wave conversion element to substantially increase a full-well capacity and improve dynamic range.
  • the second electromagnetic wave conversion element may have a circular, elliptic, or polygonal shape in a plan view.
  • the second electromagnetic wave conversion element may be at least partially embedded in the first electromagnetic wave conversion element on the second surface.
  • the second electromagnetic wave conversion element can be fabricated by known etching process.
  • the first electromagnetic wave conversion element may comprise a fin portion protruded from the second surface
  • the second electromagnetic wave conversion element may at least partially cover the fin portion.
  • the second electromagnetic wave conversion element can be fabricated by the known etching process.
  • the second electromagnetic wave conversion element may have a semicircular or polygonal shape in a cross-sectional view.
  • the second electromagnetic wave conversion element can be fabricated by the known etching process.
  • the STI may be disposed to be in contact with the second electromagnetic wave conversion element
  • the STI may be filled with an insulation material.
  • the second electromagnetic wave conversion element can be fabricated by the known etching process.
  • a second embodiment of the present invention provides an image apparatus array comprising the image apparatuses according to the first embodiment of the present invention
  • the second electromagnetic wave conversion element of at least one image apparatus is shifted from a center of the image apparatus toward a center of the image apparatus array in a plan view.
  • the image apparatus array detecting electromagnetic wave having wide dynamic range can be obtained.
  • a third embodiment of the present invention provides an image sensor comprising any one of the image apparatus described above, or the image apparatus described above.
  • the image sensor array detecting electromagnetic wave having wide dynamic range can be obtained.
  • Another aspect of the third embodiment of the present invention provides a Time-of-Flight (TOF) sensor comprising any one of the image apparatus described above, or the image apparatus array described above.
  • TOF Time-of-Flight
  • Another aspect of the third embodiment of the present invention provides an electronic apparatus comprising any one of the image apparatus described above, or the image apparatus array described above.
  • a fourth embodiment of the present invention provides a method of manufacturing an image apparatus, comprising at least:
  • the second electromagnetic wave conversion element comprising a second material having a second bandgap different from the first bandgap by epitaxial growing;
  • DTI deep trench isolation
  • the image apparatus detecting electromagnetic wave with wide dynamic range can be obtained.
  • the step of forming the second electromagnetic wave conversion element may comprise:
  • the buffer layer may reduce the lattice mismatch to reduce or avoid dislocation defects.
  • the buffer layer may be configured such that, closer to the second electromagnetic wave conversion element, a concentration of the second material may be higher.
  • the buffer layer may reduce the lattice mismatch to reduce or avoid dislocation defects.
  • the buffer layer may be configured such that, closer to the second electromagnetic wave conversion element, a concentration of doping may be higher.
  • the buffer layer may reduce the lattice mismatch to reduce or avoid dislocation defects.
  • the first material may be silicon
  • the second material may be selected from the group consisting of SiGe, germanium, InGaAs, GaAs, a III-V material, quantum dots, an organic material, an inorganic material, or other radiation sensitive material, or combinations thereof.
  • electromagnetic wave can be detected with wide dynamic range.
  • the method may further comprise forming a second DTI at least partially surrounding the first DTI.
  • the method may further comprise forming a light-condensing element configured to condense electromagnetic wave impinging the first surface to the second electromagnetic wave conversion element.
  • the detection efficiency is improved.
  • Figure 1 shows a cross-sectional diagram of a solid-state imaging device according to a first embodiment of the present invention.
  • Figure 2 shows a plan-view diagram of the solid-state imaging device of Figure 1.
  • Figure 3 shows a partially expanded diagram of the solid-state imaging device of Figure 1.
  • Figure 4 shows a circuit diagram of the solid-state imaging device according to the first embodiment of the present invention.
  • Figure 5 shows an imaging system having a plurality of solid-state imaging device arranged in an array.
  • Figure 6 shows cross-sectional diagrams of solid-state imaging devices according to some embodiments of the present invention.
  • Figure 7 shows plan-view diagrams of solid-state imaging devices according to some embodiments of the present invention.
  • Figure 8 shows plan-view diagrams of solid-state imaging devices according to some embodiments of the present invention.
  • Figure 9 shows cross-sectional diagrams of solid-state imaging devices according to some embodiments of the present invention.
  • Figure 10 shows cross-sectional diagrams of solid-state imaging devices according to some embodiments of the present invention.
  • Figure 11 shows cross-sectional diagrams of solid-state imaging devices according to some embodiments of the present invention.
  • Figure 12 shows cross-sectional diagrams of solid-state imaging devices according to some embodiments of the present invention.
  • Figure 13 shows cross-sectional diagrams of solid-state imaging devices according to some embodiments of the present invention.
  • Figure 14 shows plan-view diagrams of solid-state imaging devices according to some embodiments of the present invention.
  • Figure 15 shows expanded cross-sectional diagrams of the first and second electromagnetic wave conversion elements of solid-state imaging devices according to some embodiments of the present invention.
  • Figure 16 shows cross-sectional diagrams of solid-state imaging devices according to some embodiment of the present invention included in a solid-state imaging device array according to the present invention.
  • Figure 17 shows a method for fabricating a solid-state imaging device according to some embodiments of the present invention.
  • Figure 18 shows partial cross-sectional diagram of a solid-state imaging device array including solid-state imaging devices according to some embodiments of the present invention.
  • Figure 19 shows oblique-view diagrams of image sensors including a solid-state imaging device array according to some embodiments of the present invention.
  • Figure 20 shows a block diagram of an image sensor.
  • Figure 21 shows application examples of the solid-state imaging device according to the present invention.
  • Figure 22 shows an application example of the solid-state imaging device according to the present invention.
  • Figure 23 shows a conventional solid-state imaging device.
  • Figure 24 shows a conventional solid-state imaging device.
  • Figure 25 shows a conventional solid-state imaging device.
  • first and second features may not be in direct contact.
  • present disclosure may repeat reference numerals and/or letters in the various examples. This repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various embodiments and/or configurations discussed.
  • Figure 1 shows a cross-sectional diagram of an image apparatus, in particular a solid-state imaging device 1 according to a first embodiment of the present invention.
  • Figure 2 shows a plan-view of the solid-state imaging device 1 of Figure 1.
  • Figure 3 shows a partially-expanded diagram of the solid-state imaging device 1 of Figure 1.
  • Figure 4 shows a circuit diagram of the solid-state imaging device 1.
  • Figure 5 shows an imaging system 201 comprising a plurality of solid-state imaging devices 1 arranged in an array.
  • the solid-state imaging device 1 comprises a substrate 2 having a first surface 4 and a second surface 6 opposite to the first surface 4.
  • the first surface 4 is an impinging surface which electromagnetic wave such as visible light and/or light having a short wave infrared (SWIR) wavelength impinges.
  • a first electromagnetic wave conversion element 8 comprising a first material having a first bandgap is located in the substrate 2.
  • a second electromagnetic wave conversion element 10 comprising a second material having a second bandgap different from the first bandgap is disposed on a side of the second surface 6 such that the second electromagnetic wave conversion element 10 overlaps the first electromagnetic wave conversion element 8 in a plan view.
  • the term of “in a plan view” generally means a direction seeing the substrate 2 along the direction perpendicular to the first surface 4 of the substrate 2, or a direction seeing the substrate 2 along the direction perpendicular to the second surface 6 of the substrate 2.
  • the solid-state imaging device 2 further comprises at least one first deep trench isolation (DTI) 12 extending into the substrate 2 from the first surface 4 toward the second surface 6 of the substrate 2.
  • the first DTI 12 at least partially surrounds the first electromagnetic wave conversion element 8 and the second electromagnetic wave conversion element 10 in a plan view.
  • the first DTI 12 may be formed, for example, by filling an insulation material in a trench formed on the substrate 2.
  • the second bandgap is smaller than the first bandgap.
  • the first electromagnetic wave conversion element 8 may have a sensitivity for visible light
  • the second electromagnetic wave conversion element 10 may have a sensitivity for SWIR light.
  • the first material composing the first electromagnetic wave conversion element 8 may be a semiconductor material such as silicon.
  • the second material composing the second electromagnetic wave conversion element 10 may be a material selected from the group including SiGe, germanium, InGaAs, a III-V material, quantum dots, an organic material, an inorganic material, and other radiation sensitive material, and any combinations thereof.
  • the first material composing the first electromagnetic wave conversion element 8 may be silicon
  • the second material composing the second electromagnetic wave conversion element 10 may be germanium.
  • the first electromagnetic wave conversion element 8 and the second electromagnetic wave conversion element 10 may be appropriately doped such that the first and second electromagnetic wave conversion elements 8, 10 form photodiodes, respectively.
  • the substrate 2 may be a p-type substrate.
  • a portion of the first electromagnetic wave conversion element 8 closer to the first surface 4 of the substrate 2 may be n-doped.
  • a portion of the first electromagnetic wave conversion element 8 closed to the second surface 6 of the substrate 2 may be n doped.
  • the second electromagnetic wave conversion element 10 may be p+ doped.
  • Figure 3 shows an expanded view of the first electromagnetic wave conversion element 8 and the second electromagnetic wave conversion element 10.
  • a buffer layer 11 may be disposed between the first electromagnetic wave conversion element 8 and the second electromagnetic wave conversion element 10.
  • the buffer layer 11 may be configured to reduce or prevent dislocation defects due to a lattice mismatch between the first electromagnetic wave conversion element 8 and the second electromagnetic wave conversion element 10.
  • the buffer layer 11 may comprise the first material composing the first electromagnetic wave conversion element 8 and the second material composing the second electromagnetic wave conversion element 10.
  • the buffer layer 11 may be configured such that, closer to the first electromagnetic wave conversion element 8, the concentration of the first material is higher, and such that, closer to the second electromagnetic wave conversion element 10, the concentration of the second material is higher.
  • the concentration ratio of the first material and the second material may be configured to vary in the buffer layer 11 in a stepped manner. Alternatively, the concentration ratio of the first material and the second material may be configured to continuously vary. Therefore, the lattice mismatch between the first electromagnetic wave conversion element 8 and the second electromagnetic wave conversion element 10 may be relaxed, which allows the dislocation defects to be reduced or prevented.
  • the planar dimension of the buffer layer 11 and the second electromagnetic wave conversion element 10 may be, for example, in a range approximately between 0.005 ⁇ m and 1 ⁇ m.
  • the buffer layer 11 may comprise only the first material, only the second material, or the first material and the second material at a constant concentration ratio across the entire buffer layer 11.
  • the doping concentration of the buffer layer 11 may be configured to vary from the first electromagnetic wave conversion element 8 to the second electromagnetic wave conversion element 10 in a continuous or stepped manner. Therefore, the lattice mismatch and/or stresses between the first electromagnetic wave conversion element 8 and the second electromagnetic wave conversion element 10 may be relaxed, which allows dislocation defects to be reduced or prevented.
  • the buffer layer 11 and the second electromagnetic wave conversion element 10 may be formed by (111) facet growth. Such growth may elastically relax strained layers without forming defects. Furthermore, the structure may grow in a free space along at least two directions, which also allows the elastic relaxation.
  • a micro-lens 14 for condensing impinging light and a grid structure 16, which is a light-shielding layer preventing stray light from entering adjacent imaging devices, are disposed on the first surface 4 of the substrate 2.
  • the grid structure 16 may be disposed along a periphery of the solid-state imaging device 1.
  • a floating diffusion region 18 and readout transistors 30 for reading out charge signals from the first electromagnetic wave conversion element 8 and the second electromagnetic wave conversion element 10 may be disposed on the second surface 6 of the substrate 2.
  • the readout transistors 30 may comprise a charge transfer gate 20, a source follower device 22, a row select device 24, a reset device 26, and a dual conversion gain device 28.
  • the first electromagnetic wave conversion element 8 and/or the second electromagnetic wave conversion element 10 may be coupled to the floating diffusion region 18 via the charge transfer gate 20.
  • the floating diffusion region 18 may be coupled to a gate of the source follower device 22.
  • a drain of the source follower device 22 may be coupled to a device power source 32, and a source of the source follower device 22 may be coupled to a drain of the row select device 24.
  • a source of the row select device 24 may be coupled to a column output line 34.
  • the reset device 26 may be disposed between the device power source 32 and the floating diffusion region 18.
  • the dual conversion gain device 28 may be disposed between the reset device 26 and the floating diffusion region 18.
  • the first DTI 12 is configured to at least partially surround the first electromagnetic wave conversion element 8 and the second electromagnetic wave conversion element 10 in a plan view. Therefore, the light reflected by the first DTI 12 may reach the second surface 6 and be condensed to the second electromagnetic wave conversion element 10. The light reaching the second electromagnetic wave conversion element 10 may cause charges by optoelectronic conversion.
  • the charges caused in the second electromagnetic wave conversion element 10 by the optoelectronic conversion may be transferred to the floating diffusion 18 by turning the charge transfer gate 20 on. Since the floating diffusion region 18 is coupled to the gate of the source follower device 22, the amount of the charges transferred to the floating diffusion region 18 may be gained by the source follower device 22. When the row select device 24 is turned on, a signal gained in response to the amount of the charges transferred to the floating diffusion region 18, for example, a gained current flows through the column output line 34. The amount of light impinging the second electromagnetic wave conversion element 10 can be measured by detecting the signal output to the column output line 34.
  • a signal is obtained by carrying out a correlating double sampling (CDS) which uses a difference between a reset level and a signal level.
  • CDS correlating double sampling
  • the reset level is sampled after the reset operation and before the charge transfer gate 20 is turned on, and the signal level is sampled after the charge transfer gate 20 is turned off and before the row select device 24 is turned off.
  • the reset device 26 may be turned on to reset the floating diffusion region 18.
  • the full-well capacity may be optimized by the dual conversion gain device 28 to improve the dynamic range.
  • a similar circuit for readout of the first electromagnetic wave conversion element 8 may be provided in some embodiments.
  • the readout circuit for the first electromagnetic wave conversion element 8 may share at least one of the components of the readout circuit for the second electromagnetic wave conversion element 10.
  • Such a configuration may allow the solid-state imaging device 1 to have sensitivity for both of the visible light and the SWIR light, which leads to a broad band response.
  • an “event driven” type of an image sensor may be implemented by using the solid state imaging device 100 according to the present invention.
  • the event driven type of the image sensor may output data in an asynchronous way, in other words, at any time in response to changes in the intensity of electromagnetic radiation incident on one or more pixels.
  • an event of an intensity of the electromagnetic radiation exceeding the threshold value or data representing the intensity of the electromagnetic radiation may be output along with coordinates of the one or more pixels (for example, x and y coordinates in the pixel array) and timing information.
  • photodiodes may be used in time-of-flight (TOF) applications.
  • TOF time-of-flight
  • indirect TOF sensors which send out continuous and modulated light and measure a phase of reflected light to calculate a distance to an object.
  • direct TOF sensors which send out short pulses of light that last just a few nanoseconds and then measure time which it takes for some of the emitted light to be reflected back.
  • a direct TOF sensor may have a configuration referred to as a single photon avalanche diode (SPAD) .
  • a pixel having such a photodiode comprises a high electric field region in the pixel.
  • the SPAD can generate a large amount of pixel charges even if the intensity of an incident electromagnetic wave is small, and therefore can contribute to high sensitivity of imaging and a high accuracy of distance measurement using the image sensor.
  • the imaging system 201 may comprise a pixel array 209 comprising the solid-state imaging devices 1 arranged in an array, a control circuit 205 for controlling the pixel array 209, bit lines 204 each coupled to the column output line 34 of the solid-state imaging devices 1 in each column of the pixel array 209, and a readout circuit 210 to which the bit lines 204 are coupled, and a signal processing circuit 206 to which output from the readout circuit 210 is coupled.
  • the control circuit 205 may carry out readout scanning for each row, and the signal processing circuit 206 may process the readout signals to obtain a two-dimensional image.
  • Figure 6 shows cross-sectional diagrams of solid-state imaging devices 601 to 607 according to some embodiments of the present invention.
  • the first DTI 12 may be disposed at a periphery of the solid-state imaging device 601 in a plan view.
  • the first DTI 12 realizes device isolation from adjacent solid-state imaging devices as well as the first DTI 12 directs impinging light to the second electromagnetic wave conversion element 10. Therefore, cross-talk due to the adjacent solid-state imaging devices may be reduced.
  • the volume of the first electromagnetic wave conversion element 8 may be maximized to increase the full-well capacity.
  • the depth of the first DTI 12 is smaller than the thickness of the substrate 2, the first DTI 12 does not reach the second surface 6.
  • a DTI having a depth smaller than the thickness of the substrate may also be referred to as a partial depth DTI.
  • the partial depth DTI may, for example, reduce the width of the DTI.
  • the degree of freedom of designs of the readout transistors and other components and wirings disposed on the second surface 6 may be increased.
  • the depth of the first DTI 12 may be equal to the thickness of the substrate 2. In this case, the first DTI 12 reaches the second surface 6 to realize complete device isolation.
  • the first DTI 12 may be disposed inward of the periphery of the solid-state imaging device 1 in a plan view.
  • the optoelectronic conversion efficiency (or the quantum efficiency) of the second electromagnetic wave conversion element 10 may be improved.
  • the depth of the first DTI 12 is smaller than the thickness of the substrate 2, and therefore the first DTI 12 does not reach the second surface 6.
  • the depth of the first DTI 12 may be equal to the thickness of the substrate 2. In this case, the first DTI 12 may reach the second surface 6 to realize complete device isolation.
  • each of the solid-state imaging devices 603 to 607 may further comprise a second DTI 36 disposed at the periphery of each of the solid-state imaging devices 603 to 607 and at least partially surrounding the first DTI 12 in a plan view.
  • Both the first DTI 12 and the second DTI36 may be partial depth DTIs of which depths are smaller than the thickness of the substrate, or may be complete DTIs of which depths are equal to the thickness of the substrate.
  • the depth of the first DTI 12 of the solid-state imaging device 603 shown in Figure 6 (C) is smaller than the thickness of the substrate 2, the first DTI 12 does not reach the second surface 6.
  • the depth of the second DTI 36 is equal to the thickness of the substrate 2, the second DTI 36 may reach the second surface 6.
  • the depth of the first DTI 12 of the solid-state imaging device 604 shown in Figure 6 (D) is equal to the thickness of the substrate 2, the first DTI 12 may reach the second surface 6.
  • the depth of the second DTI 36 is smaller than the thickness of the substrate 2, the second DTI 36 does not reach the second surface 6.
  • the first DTI 12 and the second DTI 36 of the solid-state imaging device 605 shown in Figure 6 (E) are smaller than the thickness of the substrate 2, the first DTI 12 and the second DTI 36 may not reach the second surface 6.
  • the width of the first DTI 12 of the solid-state imaging device 606 shown in Figure 6 (F) in a plan view may be larger than the width of the second DTI 36.
  • the depth of the first DTI 12 is equal to the thickness of the substrate 2, and the depth of the second DTI 36 is smaller than the thickness of the substrate 2.
  • the depths of the first DTI 12 and the second DTI 36 are not limited to those shown in Figure 6 (F) .
  • the width of the first DTI 12 of the solid-state imaging device 607 shown in Figure 6 (G) in a plan view may be smaller than the width of the second DTI 36.
  • the depth of the first DTI 12 is equal to the thickness of the substrate 2, and the depth of the second DTI 36 is smaller than the thickness of the substrate 2.
  • the depths of the first DTI 12 and the second DTI 36 are not limited to those shown in Figure 6 (G) .
  • Figure 7 shows plan-view diagrams of solid-state imaging devices 701 to 706 according to some embodiments of the present invention, seen from the side of the second surface 6 of the substrate 2.
  • the first electromagnetic wave conversion element 8 of each of the solid-state imaging devices 701 to 706 shown in Figure 7 has a polygonal shape in a plan view.
  • the shape of the first electromagnetic wave conversion element 8 may be a regular polygon or a non-regular polygon.
  • the first DTI 12 of each of the solid-state imaging devices 701 to 706 may be disposed to at least partially surround the first electromagnetic wave conversion element 8 having a polygonal shape.
  • the first DTI 12 may be disposed at along at least parts of at least two sides of the first electromagnetic wave conversion element 8 having a polygonal shape.
  • the first DTI 12 of each of the solid-state imaging device 701 to 706 may at least partially separate the first electromagnetic wave conversion element 8 from at least one of the floating diffusion region 18, the source follower device 22, the row select device 24, the reset device 26, and the dual conversion gain device 28.
  • the shape of the first electromagnetic wave conversion element 8 of the solid-state imaging device 701 shown in Figure 7 (A) is a square shape in a plan view.
  • the first DTI 12 may be disposed along three sides of the first electromagnetic wave conversion element 8.
  • the first DTI 12 may not be disposed along one side of the first electromagnetic wave conversion element 8.
  • the first DTI 12 may at least partially separate the first electromagnetic wave conversion element 8 from the floating diffusion region 18, the source follower device 22, and the row select device 24.
  • the first DTI 12 may not separate the first electromagnetic wave conversion element from the reset device 26 and the dual conversion gain device 28.
  • the shape of the first electromagnetic wave conversion element 8 of the solid-state imaging device 702 shown in Figure 7 (B) is a square shape or a rectangular shape in a plan view.
  • the first DTI 12 may be disposed along two sides of the first electromagnetic wave conversion element 8 facing each other.
  • the first DTI 12 may not be disposed along the other two sides of the first electromagnetic wave conversion element 8 facing each other.
  • the first DTI 12 may at least partially separate the first electromagnetic wave conversion element 8 from the floating diffusion region 18, the source follower device 22, and the row select device 24.
  • the first DTI 12 may not separate the first electromagnetic wave conversion element 8 from the reset device 26 and the dual conversion gain device 28.
  • the shape of the first electromagnetic wave conversion element 8 of the solid-state imaging device 703 shown in Figure 7 (C) is a square shape in a plan view.
  • the first DTI 12 may be disposed along parts of four sides of the first electromagnetic wave conversion element 8. Therefore, the first DTI 12 is composed of four DTIs which are not connected with each other, and at least partially surrounds the first electromagnetic wave conversion element 8.
  • the first DTI 12 may at least partially separate the first electromagnetic wave conversion element 8 from the source follower device 22, the reset device 26, and the dual conversion gain device 28.
  • the first DTI 12 may not separate the first electromagnetic wave conversion element 8 from the floating diffusion region 18 and the row select device 24.
  • the shape of the first electromagnetic wave conversion element 8 of the solid-state imaging device 704 shown in Figure 7 (D) is a square shape in a plan view.
  • the first DTI 12 may be disposed along parts of four sides of the first electromagnetic wave conversion element 8. Therefore, the first DTI 12 is composed of four DTIs which are not connected with each other, and at least partially surrounds the first electromagnetic wave conversion element 8.
  • the first DTI 12 may at least partially separate the first electromagnetic wave conversion element 8 from the floating diffusion region 18, the source follower device 22, the row select device 24, the reset device 26, and the dual conversion gain device 28.
  • the shape of the first electromagnetic wave conversion element 8 of the solid-state imaging device 705 shown in Figure 7 (E) is an octagonal shape in a plan view.
  • the first DTI 12 may be disposed along seven sides of the first electromagnetic wave conversion element 8. The parts of the first DTI 12 disposed along sides adjacent to a side, along which the first DTI 12 is not disposed, are extended and connected with each other. Therefore, the first DTI 12 may separate the first electromagnetic wave conversion element 8 from the floating diffusion region 18, the source follower device 22, the row select device 24, the reset device 26, and the dual conversion gain device 28.
  • the shape of the first electromagnetic wave conversion element 8 of the solid-state imaging device 706 shown in Figure 7 (F) is an octagonal shape in a plan view.
  • the first DTI 12 may be disposed along seven sides of the first electromagnetic wave conversion element 8. The parts of the first DTI 12 disposed along sides adjacent to a side, along which the first DTI 12 is not disposed, are not connected with each other.
  • the first DTI 12 may separate the first electromagnetic wave conversion element 8 from the source follower device 22, the row select device 24, the reset device 26, and the dual conversion gain device 28.
  • the first DTI 12 may not separate the first electromagnetic wave conversion element 8 from the floating diffusion region 18.
  • Figure 8 shows plan-view diagrams of solid-state imaging devices 801 to 804 according to some embodiments of the present invention seen from the side of the second surface 6 of the substrate 2.
  • the first DTI 12 of each of the solid-state imaging devices 801 to 804 shown in Figure 8 at least partially surrounds the first electromagnetic wave conversion element 8, and a part of the second DTI 36 at least partially surrounds the first electromagnetic wave conversion element 8. Therefore, the first electromagnetic wave conversion element 8 may be at least partially surrounded by the first DTI 12 and the second DTI 36. Different from the case in which only the first DTI 21 surrounds the first electromagnetic wave conversion element 8, the planar area of the first DTI 12 may be reduced. Therefore, for example, the volume of the first electromagnetic wave conversion element 8 may be increased to improve the dynamic range.
  • the first DTI 12 of the solid-state imaging device 801 shown in Figure 8 (A) is connected to the second DTI 36 to surround the first electromagnetic wave conversion element 8.
  • the first DTI 12 and the part of the second DTI 36 may collectively have a polygonal shape such as a square shape in a plan view.
  • the first DTI 12 the solid-state imaging device 802 shown in Figure 8 (B) is connected to the second DTI 36 to surround the first electromagnetic wave conversion element 8.
  • the first DTI 12 and the part of the second DTI 36 may collectively have a polygonal shape such as a pentagonal shape in a plan view.
  • the shape of the first DTI 12 shown in Figure 8 (B) may increase a spatial efficiency of the solid-state imaging device 802. Therefore, a configuration shown in Figure 8 (B) may improve the degree of freedom of the design of the readout transistors and may provide miniaturization of the solid-state imaging device 802.
  • the first DTI 12 of the solid-state imaging device 803 shown in Figure 8 (C) is connected to the second DTI 36 to surround the first electromagnetic wave conversion element 8.
  • the first DTI 12 and the part of the second DTI 36 may collectively have a polygonal shape such as a square shape in a plan view.
  • the DTI 12-1 and the DTI 12-2, which compose the sides of the first DTI 12 are not connected to each other. Therefore, the first DTI 12 and the second DTI 36 partially surround the first electromagnetic wave conversion element 8.
  • the first DTI 12 and the part of the second DTI 36 of the solid-state imaging device 804 shown in Figure 8 (D) surround the first electromagnetic wave conversion element 8.
  • the first DTI 12 and the part of the second DTI 36 may collectively have a polygonal shape such as a square shape in a plan view.
  • the DTI 12-1 and the DTI 12-2, which compose the sides of the first DTI 12 are not connected to each other.
  • the DTI 12-1 and the DTI12-2 are not connected to the second DTI 36. Therefore, the first DTI 12 and the second DTI 36 may partially surround the first electromagnetic wave conversion element 8.
  • FIG. 9 shows cross-sectional diagrams of each of solid-state imaging devices 901 and 902 according to some embodiments of the present invention.
  • Each of the solid-state imaging devices 901 and 902 shown in Figure 9 further comprise a light condensing element configured to condense the SWIR light impinging the first surface 4 to the second electromagnetic wave conversion element 10.
  • Light condensing elements having various shape may be applied. Condensing light to the second electromagnetic wave conversion element 10 may increase the quantum efficiency, for example, the optoelectronic conversion efficiency.
  • the solid-state imaging device 901 shown in Figure 9 (A) may comprise at least one recess 911 disposed on the first side 4 of the substrate 2 as a light condensing element.
  • the recess 911 may be, for example, filled with a transparent insulation material.
  • the recess 911 may be disposed to overlap the second electromagnetic wave conversion element 10 in a plan view.
  • the cross-section of the recess 911 may have, for example, a triangle shape of which vertex is disposed in the substrate 2.
  • the recess 911 may reflect, refract, and/or diffract SWIR light impinging the first surface 4 to condense the SWIR light to the second electromagnetic wave conversion element 10.
  • the solid-state imaging device 902 shown in Figure 9 (B) may comprise at least one recess 912 disposed on the first surface 4 of the substrate 2 as a light condensing element.
  • Figure 9 (B) shows a plurality of recesses 912.
  • the recesses 912 may be, for example, filled with a transparent insulation material.
  • the cross section of the recesses 912 are for example rectangular.
  • At least one of the recesses 912 is disposed to overlap the second electromagnetic wave conversion element 10 in a plan view.
  • the other recesses 912 may be disposed to, for example, surround the second electromagnetic wave conversion element 10 in a plan view.
  • the recesses 912 may reflect, refract, and/or diffract SWIR light impinging the first surface 4 to condense the SWIR light to the second electromagnetic wave conversion element 10.
  • FIG. 10 shows cross-sectional diagrams of solid-state imaging devices 1001 to 1005 according to some embodiments of the present invention.
  • Each of the solid-state imaging device 1001 to 1005 shown in Figure 10 may further comprise a light condensing element configured to condense SWIR light impinging the first surface 4 to the second electromagnetic wave conversion element 10.
  • Light condensing elements having various shape may be applied. Condensing light to the second electromagnetic wave conversion element 10 may increase the quantum efficiency, for example, the optoelectronic conversion efficiency.
  • the first DTI 12 of the solid-state imaging device 1001 shown in Figure 10 (A) extends from the first surface 4 of the substrate 2 to the second surface 6.
  • the end of the first DTI 12 on the side of the second surface 6 comprises a taper portion 1011 having a width which becomes larger toward the second surface 6 in a cross-sectional view.
  • the taper portion 1011 extends toward the second electromagnetic wave conversion element 10 in a plan view closer to the second surface 6.
  • the taper portion 1011 may function as a light condensing element which reflect and direct the SWIR light to the second electromagnetic wave conversion element 10.
  • the solid-state imaging device 1002 shown in Figure 10 (B) may comprise a shallow trench isolation (STI) 1012 disposed inward of the first DTI 12 in a plan view to at least partially surround the second electromagnetic wave conversion element 10.
  • the STI 1012 may be a trench extending from the second surface 6 toward inside of the substrate 2 and filled with an insulation material or the like.
  • the STI 1012 may function as a light condensing element which reflects SWIR light to condense the SWIR light to the second electromagnetic wave conversion element 10.
  • the solid-state imaging device 1003 shown in Figure 10 (C) may comprise a grid structure 16 which is a light shielding layer disposed on the first surface 4 of the substrate 2.
  • the grid structure 16 may comprise an aperture 1013 extended inward of the first DTI 21 and overlapping the first electromagnetic wave conversion element 8 in a plan view.
  • the SWIR light is collimated when passing the aperture 1013 and is condensed to the second electromagnetic wave conversion element 10.
  • a reflected electromagnetic wave passing through the substrate 2 from the direction of the surface 6 may be reflected by the bottom surface of the grid structure 16 and be directed to the second electromagnetic wave conversion element 10. Therefore, the aperture 1013 may function as a light condensing element.
  • the solid-state imaging device 1004 shown in Figure 10 (D) may comprise a micro-lens 1014 on the first surface 4 of the substrate 2.
  • the micro-lens 1014 may overlap the first electromagnetic wave conversion element 8 in a plan view.
  • the micro-lens 1014 may function as a light condensing element refracting SWIR light to condense the SWIR light to the second electromagnetic wave conversion element 10.
  • the solid-state imaging device 1005 shown in Figure 10 (E) may comprise a reflection layer 1015 disposed over the second surface 6 of the substrate 2.
  • the reflection layer 1015 may be made by a gate of a device or a metal-0 layer.
  • the reflection layer 1015 may at least partially surround the second electromagnetic wave conversion element 10 in a plan view.
  • SWIR light not impinging the second electromagnetic wave conversion element 10 and reaching the second surface 6 of the substrate 2 may be reflected on the reflection layer 1015 back to the substrate 2.
  • the reflected SWIR light may be reflected on the first surface 4 of the substrate 2 and/or the first DTI 12 to impinge the second electromagnetic wave conversion element 10. Therefore, the reflection layer 1015 may function as a light condensing element.
  • FIG 11 shows cross-sectional diagrams of solid-state imaging devices 1101 to 1105 according to some embodiments of the present invention.
  • Each of the solid-state imaging devices 1101 to 1105 shown in Figure 11 may further comprise a light condensing element configured to condense SWIR light impinging the first surface 4 to the second electromagnetic wave conversion element 10.
  • Light condensing elements having various shape may be applied. Condensing light to the second electromagnetic wave conversion element 10 may increase the quantum efficiency, for example, the optoelectronic conversion efficiency.
  • the solid-state imaging device 1101 shown in Figure 11 (A) may comprise an insulation film 1108 disposed on the second surface 6 of the substrate 2. At least one metal layer 1111 is disposed in the insulation film 1108.
  • the metal layer 1111 may be configured to be separated from the second electromagnetic wave conversion element 10 and configured to overlap the second electromagnetic wave conversion element 10 in a plan view.
  • the metal layer 1111 may reflect light passing through the substrate 2 without impinging the second electromagnetic wave conversion element 10 back to the substrate 2 and/or the second electromagnetic wave conversion element 10. Therefore, the metal layer 1111 may function as a light condensing element.
  • the metal layer 1111 may function as wirings for reading signals as well as functioning as the light condensing element.
  • the solid-state imaging device 1102 shown in Figure 11 (B) may comprise an insulation film 1108 dispose on the second surface 6 of the substrate 2. At least one metal layer 1112 is disposed in the insulation film 1108.
  • the metal layer 1112 may be configured to be separated from the second electromagnetic wave conversion element 10.
  • a first metal layer 1112-1 among the metal layers 1112 may be disposed to overlap the second electromagnetic wave conversion element 10 in a plan view.
  • a second metal layer 1112-2 among the metal layers 1112 may be disposed to at least partially surround the second electromagnetic wave conversion element 10 in a plan view.
  • the first metal layer 1112-1 may be disposed on a level different form the second metal layer 1112-2, or may be disposed on the same level as the second metal layer 1112-2.
  • the first metal layer 1112-1 and/or the second metal layer 1112-2 may reflect light passing through the substrate 2 without impinging the second electromagnetic wave conversion element 10 back to the substrate 2 and/or the second electromagnetic wave conversion element 10. Therefore, the first metal layer 1112-1 and/or the second metal layer 1112-2 may function as a light condensing element.
  • the first metal layer 1112-1 and/or the second metal layer 1112-2 may function as wirings for reading signals as well as function as a light condensing element.
  • the solid-state imaging device 1103 shown in Figure 11 (C) may comprise a reflection layer 1113 disposed on an outer surface of the second electromagnetic wave conversion element 10 and at least partially surrounding the second electromagnetic wave conversion element 10.
  • the reflection layer 1113 may be, for example, a silicidation layer.
  • the reflection layer 1113 may reflect SWIR layer impinging but passing through the second electromagnetic wave conversion element 10 back to the second electromagnetic wave conversion element 10. Therefore, the reflection layer 1113 may function as a light condensing element.
  • the solid-state imaging device 1104 shown in Figure 11 (D) may comprise an insulation film 1108 disposed on the second surface 6 of the substrate 2. At least one metal layer 1114 is disposed in the insulation film 1108. The metal layers 1114 are separated from the second electromagnetic wave conversion element 10. A first metal layer 1114-1 among the metal layers 1114 may be disposed to overlap the second electromagnetic wave conversion element 10 in a plan view. A second metal layer 1114-2 among the metal layers 1114 may be disposed to at least partially surround the second electromagnetic wave conversion element 10 in a plan view. The second metal layer 1114-2 may be electrically coupled to the first electromagnetic wave conversion element 8 and/or the second electromagnetic wave conversion element 10 via contacts 1124. The contacts 1124 may be disposed to at least partially surround the second electromagnetic wave conversion element 10.
  • the second metal layer 1114-2 and the contacts 1124 may function as a fixing surface pinning layer potential to ground or negative bias in case of the n-type photodiode.
  • the first metal layer 1114-1 may be disposed at a level different from a lever of the second metal layer 1114-2, or may be disposed at the same level as the level of the second metal layer 1114-2.
  • the first metal layer 1114-1 and/or the second metal layer 1114-2 reflects light passing through the substrate 2 without impinging the second electromagnetic wave conversion element 10 back to the substrate 2 and/or the second electromagnetic wave conversion element 10.
  • the contacts 1124 may direct the SWIR light reflected by the first metal layer 1114-1 and/or the second metal layer 1114-2 to the second electromagnetic wave conversion element 10. Therefore, the first metal layer 1114-1, the second metal layer 1114-2, and the contacts 1124 may function as a light condensing element.
  • the solid-state imaging device 1105 shown in Figure 11 (E) comprises an insulation film 1108 disposed on the second surface 6 of the substrate 2. At least one metal layer 1115 is disposed in the insulation layer 1108. The metal layers 1115 are separated from the second electromagnetic wave conversion element 10. A first metal layer 1115-1 among the metal layers 1115 may be disposed to overlap the second electromagnetic wave conversion element 10 in a plan view. A second metal layer 1115-2 among the metal layers 1115 may be disposed to at least partially surround the second electromagnetic wave conversion element 10 in a plan view. The first metal layer 1115-1 may be electrically coupled to the second metal layer 1115-2 through vias 1125. The vias 11125 may be disposed to at least partially surround the second electromagnetic wave conversion element 10 in a plan view.
  • the first metal layer 1115-1 may be disposed at a level different from the level of the second metal layer 1115-2.
  • the first metal layer 1115-1 and/or the second metal layer 1115-2 reflect light passing through the substrate 2 without impinging the second electromagnetic wave conversion element 10 back to the substrate 2 and/or the second electromagnetic wave conversion element 10.
  • the vias 1125 may direct the SWIR light reflected by the first metal layer 1115-1 and/or the second metal layer 1115-2 to the second electromagnetic wave conversion element 10. Therefore, the first metal layer 1115-1, the second metal layer 1115-2, and the vias 1125 may function as a light condensing element.
  • Figure 12 shows cross-sectional diagrams of solid-state imaging devices 1201 to 1206 according to some embodiments of the present invention.
  • the solid-state imaging device 1201 shown in Figure 12 (A) has a configuration similar to the solid-state imaging device 1 shown in Figure 1.
  • the first electromagnetic wave conversion element 8 and/or the second electromagnetic wave conversion element 10 may be surrounded by the first DTI 12 in a plan view.
  • the charge transfer gate 20 may be disposed on the second surface 6 of the substrate 2 to overlap the first electromagnetic wave conversion element 8 in a plan view. Charges caused by optoelectronic conversion in the first electromagnetic wave conversion element 8 and/or the second electromagnetic wave conversion element 10 may be transferred to the floating diffusion region 18 by turning the charge transfer gate 20 on.
  • the solid-state imaging device 1202 shown in Figure 12 (B) may comprise a third electromagnetic wave conversion element 1212 between the first DTI 12 and the second DTI 36.
  • the third electromagnetic wave conversion element 1212 may be separated from the first electromagnetic wave conversion element 8.
  • the charge transfer gate 20 may be disposed on the second surface 6 of the substrate 2 to overlap the first electromagnetic wave conversion element 8 in a plan view.
  • At least one charge transfer gate 1222 other than the charge transfer gate 20 may be disposed on the second surface 6 of the substrate 2 to overlap the third electromagnetic wave conversion element 1212 in a plan view.
  • the example shown in Figure 12 (B) provides two charge transfer gates 1222.
  • Charges caused by optoelectronic conversion in the first electromagnetic wave conversion element 8 and/or the second electromagnetic wave conversion element 10 may be transferred to the floating diffusion region 18 by turning the charge transfer gate 20 on.
  • charges caused by optoelectronic conversion in the third electromagnetic wave conversion element 1212 are transferred to the floating diffusion region 18 by turning the charge transfer gate 1222 on.
  • the solid-state imaging device 1203 shown in Figure 12 (C) may comprise a third electromagnetic wave conversion element 1213 between the first DTI 2 and the second DTI 36.
  • the third electromagnetic wave conversion element 1213 may be coupled to the first electromagnetic wave conversion element 8.
  • the charge transfer gate 20 may be disposed on the second surface 6 of the substrate 2 to overlap the first electromagnetic wave conversion element 8 or the third electromagnetic wave conversion element 1213 in a plan view.
  • the first electromagnetic wave conversion element 8 and the third electromagnetic wave conversion element 1213 share the charge transfer gate 20. Therefore, charges caused by optoelectronic conversion in the first electromagnetic wave conversion element 8 and/or the second electromagnetic wave conversion element 10 and/or the third electromagnetic wave conversion element 1213 are transferred to the floating diffusion region 18 by turning the charge transfer gate 20 on.
  • the solid-state imaging device 1204 shown in Figure 12 (D) may comprise a third electromagnetic wave conversion element 1214 between the first DTI 12 and the second DTI 36.
  • the third electromagnetic wave conversion element 1214 may be separated from the first electromagnetic wave conversion element 8.
  • the second DTI 36 may be disposed outward of the micro-lens 14 in a plan view, and at least a part of the third electromagnetic wave conversion element 1214 may be disposed outward of the micro lens 14 in a plan view.
  • the charge transfer gate 20 is disposed on the second surface 6 of the substrate 2 to overlap the first electromagnetic wave conversion element 8 in a plan view.
  • At least one charge transfer gate 1224 other than the charge transfer gate 20 may be disposed on the second surface 6 of the substrate 2 to overlap the third electromagnetic wave conversion element 1214 in a plan view. Charges caused by optoelectronic conversion in the first electromagnetic wave conversion element 8 and/or the second electromagnetic wave conversion element 10 are transferred to the floating diffusion region 18 by turning the charge transfer gate 20 on. Charges by optoelectronic conversion in the third electromagnetic wave conversion element 1214 are transferred to the floating diffusion region 18 by turning the charge transfer gate 1224 on.
  • the solid-state imaging device 1205 shown in Figure 12 (E) may comprise a third electromagnetic wave conversion element 1215 between the first DTI 12 and the second DTI 36.
  • the third electromagnetic wave conversion element 1215 may be coupled to the first electromagnetic wave conversion element 8.
  • the second DTI 36 may be disposed outward of the micro lens 14 in a plan view. At least a part of the third electromagnetic wave conversion element 1215 may be disposed outward of the micro lens 14 in a plan view.
  • the charge transfer gate 20 is disposed on the second surface 6 of the substrate 2 to overlap the first electromagnetic wave conversion element 8 or the third electromagnetic wave conversion element 1215 in a plan view.
  • the first electromagnetic wave conversion element 8 and the third electromagnetic wave conversion element 1215 share the charge transfer gate 20. Therefore, charges caused by optoelectronic conversion in the first electromagnetic wave conversion element 8 and/or the second electromagnetic wave conversion element 10 and/or the third electromagnetic wave conversion element 1215 are transferred to the floating diffusion region 18 by turning the charge transfer gate 20 on.
  • the solid-state imaging device 1206 shown in Figure 12 (F) has a configuration similar to the solid-state imaging device 1 shown in Figure 1.
  • the first electromagnetic wave conversion element 8 and/or the second electromagnetic wave conversion element 10 are surrounded by the first DTI 12 in a plan view.
  • the charge transfer gate 20 is disposed on the second surface 6 of the substrate 2 to overlap the first electromagnetic wave conversion element 8 in a plan view. At least a part of the charge transfer gate 20 may be extended into the substrate 2. Charges caused by optoelectronic conversion in the first electromagnetic wave conversion element 8 and/or the second electromagnetic wave conversion element 10 are transferred to the floating diffusion region 18 by turning the charge transfer gate 20 on.
  • Figure 13 shows cross-sectional diagrams of solid-state imaging devices 1301 to 1304 according to some embodiments of the present invention.
  • the solid-state imaging device 1301 shown in Figure 13 (A) comprises an insulation film 1308 disposed on the second surface 6 of the substrate 2.
  • At least one bias electrode 1311 is disposed in the insulation film 1308.
  • the at least one bias electrode 1311 is separated from the second electromagnetic wave conversion element 10.
  • the bias electrode 1311 is electrically coupled to the second electromagnetic wave conversion element 10 via contact 1321.
  • a bias voltage may be applied to the second electromagnetic wave conversion element 10 via the bias electrode 1311 and the contact 1321. Charges caused by optoelectronic conversion in the second electromagnetic wave conversion element 10 may be transferred to and stored in a charge storage region in the substrate (not shown) by applying the bias voltage.
  • the charge transfer gate is turned on to transfer the stored charges to the floating diffusion region, which results in substantially increasing the full-well capacity and improving the dynamic range. Furthermore, the application of the bias voltage to the second electromagnetic wave conversion element 10 also provides reduction of the dark current.
  • the solid-state imaging device 1302 shown in Figure 13 (B) comprises an insulation film 1308 disposed on the second surface 6 of the substrate 2.
  • At least one bias electrode 1312 is disposed in the insulation film 1308 to overlap the second electromagnetic wave conversion element 10 in a plan view.
  • the at least one bias electrode 1312 is separated from the second electromagnetic wave conversion element 10.
  • the bias electrode 1312 is electrically coupled to the second electromagnetic wave conversion element 10 in an indirect manner.
  • Application of the bias voltage to the bias electrode 1312 may provide the improvement of the dynamic range and the reduction of the dark current.
  • the solid-state imaging device 1303 shown in Figure 13 (C) further comprises a fixed charge film 1313 at least partially covering the second electromagnetic wave conversion element 10.
  • the fixed charge film 1313 may comprise a material selected from the group including, for example, HfO 2 , Al 2 O 3 , ZrO 2 , Ta 2 O 5 , TiO 2 , La 2 O 3 , Pr 2 O 3 , CeO 2 , Nd 2 O 3 , Pm 2 O 3 , Sm 2 O 3 , Eu 2 O 3 , Gd 2 O 3 , Tb 2 O 3 , Dy 2 O 3 , Ho 2 O 3 , Er 2 O 3 , Tm 2 O 3 , Yb 2 O 3 , Lu 2 O 3 , Y 2 O 3 , or any combinations thereof.
  • the fixed charge film 1313 may apply a bias voltage to the second electromagnetic wave conversion element 10 by keeping charges in the film.
  • the solid-state imaging device 1304 shown in Figure 13 (D) further comprises an intrinsic stress film 1314 at least partially covering the second electromagnetic wave conversion element 10.
  • the intrinsic stress film 1314 may be, for example, a tensile stressed silicon nitride liner or a compressively stressed silicon nitride liner.
  • the intrinsic stress film 1314 may apply a stress to the second electromagnetic wave conversion element 10 and may modulate a bandgap of the second electromagnetic wave conversion element 10.
  • the bandwidth can be tuned to longer wavelengths by admixture of a different band gap material such as Sn in the epitaxy (not shown in the figures) .
  • FIG 14 shows planar diagrams of solid-state imaging devices 1401 to 1404 according to some embodiments of the present invention.
  • the second electromagnetic wave conversion elements 10 of the solid-state imaging devices 1401 to 1404 shown in Figure 14 may have various planar shapes.
  • Such a second electromagnetic wave conversion element 10 having various planar shapes may increase a spatial efficiency, which results in all of or some of the improvements of charge transfer capability, dark current performance, and quantum efficiency.
  • Such various planar shapes may be selected by choosing, for example, a shape of a mask and an initial shape of a seed layer and a growth condition of an epitaxial growth of the second electromagnetic wave conversion element 10.
  • the second electromagnetic wave conversion element 10 of the solid-state imaging device 1401 shown in Figure 14 (A) has a circular shape in a plan view.
  • the second electromagnetic wave conversion element 10 of the solid-state imaging device 1402 shown in Figure 14 (B) has an elliptical shape in a plan view.
  • the second electromagnetic wave conversion element 10 of the solid-state imaging device 1403 shown in Figure 14 (C) has a rectangular shape in a plan view.
  • the second electromagnetic wave conversion element 10 of the solid-state imaging device 1404 shown in Figure 14 (D) has a polygonal shape in a plan view.
  • Figure 15 shows expanded cross-sectional diagrams of a first electromagnetic wave conversion element 8 and a second electromagnetic wave conversion element 10 of solid-state imaging devices according to some embodiments of the present invention.
  • a buffer layer 11 may be disposed between the first electromagnetic wave conversion element 8 and the second electromagnetic wave conversion element 10.
  • the buffer layer 11 may be configured such that, closer to the first electromagnetic wave conversion element 8, the concentration of the first material is higher, and such that, closer to the second electromagnetic wave conversion element 10, the concentration of the second material is higher.
  • the concentration ratio between the first material and the second material may be configured to continuously vary in the buffer layer 11.
  • the concentration ratio between the first material and the second material may be configured to vary in the buffer layer 11 in a stepped manner.
  • the concentration ratio between the first material and the second material may comprise only the first material, only the second material, or the first material and the second material at a constant concentration ratio across the entire buffer layer 11.
  • a concentration of doping may be configured to continuously vary from the first electromagnetic wave conversion element 8 to the second electromagnetic wave conversion element 10.
  • the doping concentration may be configured to vary in a sub-buffer layer 11-1 and a sub-buffer layer 11-2 in a stepped manner to ensure that generated photocharges in the second electromagnetic wave conversion element 10 can be transferred to the floating diffusion when the transfer gate turns on.
  • Figure 15 (A) shows a recess 1511 disposed on the second surface 6 of the substrate 2.
  • the buffer layer 11 and the second electromagnetic wave conversion element 10 may be at least partially embedded in the recess 1511.
  • the recess 1511 and the embedded second electromagnetic wave conversion element 10 may have a shape of a half-circular or a polygonal cross section.
  • Figure 15 (B) shows the second electromagnetic wave conversion element 10 deposited on the second surface 6 on the substrate 2.
  • the buffer layer 11 may be disposed in the substrate 2 by known technique such as atomic diffusion or doping.
  • the second electromagnetic wave conversion element 10 may have a half-circular or a polygonal cross section.
  • Figure 15 (C) shows a fin portion 1513 on the second surface 6 of the substrate 2.
  • the fin portion 1513 may protrude from the second surface 6 and may have the same material as the substrate 2.
  • the fin portion 1513 may be formed by deposition.
  • the fin portion 1513 may be formed by etching the surface of the substrate 2 with remaining the area to be the fin portion 1513. Isotropic or anisotropic deposition, or isotropic or anisotropic etching may provide the fin portion 1513 having various cross-sectional shape.
  • the fin portion 1513 may be a part of the first electromagnetic wave conversion element 8 by doping the fin portion 1513.
  • the second electromagnetic wave conversion element 10 may be formed to at least partially cover the fin portion 1513. By selecting a shape of the fin portion 1513, a deposition method, and an etching process after the deposition, the second electromagnetic wave conversion element 10 may have various cross-sectional shape.
  • Figure 15 (D) shows a recess 1514 on the second surface 6 of the substrate 2.
  • the buffer layer 11 and the second electromagnetic wave conversion element 10 may be at least partially embedded in the recess 1514.
  • an STI 1524 may be disposed adjacent to the buffer layer 11 and the second electromagnetic wave conversion element 10 to at least partially surround the buffer layer 11 and the second electromagnetic wave conversion element 10.
  • the STI 1524 may have various cross-sectional shapes by isotropic or anisotropic etching.
  • the STI 1524 may be filled with, for example, an insulation material.
  • a silicon capping layer may be formed on top of the second electromagnetic wave conversion element 10 (not shown in the figures) .
  • Figure 16 shows cross-sectional diagrams of solid-state imaging devices 1601 to 1602 included in a solid-state imaging device array according to some embodiments of the present invention.
  • the solid-state imaging device array comprises a plurality of solid-state imaging devices according to the present invention arranged in an array. Since the solid-state imaging device 1601 is arranged near the center of the solid-state imaging device array, light approximately vertically impinges the first surface 4 of the substrate 2. Therefore, as shown in Figure 16, the first electromagnetic wave conversion element 8, the second electromagnetic wave conversion element 10, and the micro lens 14 are aligned along the center axis of the solid-state imaging device 1601 in order to receive the light with the highest efficiency.
  • the solid-state imaging device 1602 since the solid-state imaging device 1602 is located near the periphery of the solid-state imaging device array, light may impinge the first surface 4 of the substrate 2 from the center of the solid-state imaging device array at a certain angle which has a function of a chief ray angle. Therefore, as shown in Figure 16, the first electromagnetic wave conversion element 8, the second electromagnetic wave conversion element 10, and the micro lens 14 may be shifted toward the direction of the center of the solid-state imaging device array in order to receive the light with the highest efficiency.
  • Figure 17 shows cross-sectional diagrams showing steps of a method for fabricating a solid-state imaging device 1701 according to some embodiment of the present invention.
  • a substrate 2 comprising a first material having a first bandgap is prepared.
  • the substrate 2 comprises a first surface 4 and a second surface 6 opposite to the first surface 4.
  • the first surface 4 is a surface which electromagnetic wave, for example, light impinges.
  • a first electromagnetic wave conversion element 8 is formed in the substrate 2 by doping.
  • STIs 1711 may be formed at a position on the second surface 6 of the substrate 2 where a first DTI 12 is to be formed.
  • the STIs 1711 are to be the tapered portions 1011 explained regarding Figure 10 (A) .
  • a floating diffusion region 18 and readout transistors 30 including a charge transfer gate 20, a source follower device 22, a row select device 24, a reset device 26, and a dual conversion gain device 28 for reading out charge signals from the first electromagnetic wave conversion element 8 and the second electromagnetic wave conversion element 10 are formed on the second surface 6 of the substrate 2 by known semiconductor process.
  • a second electromagnetic wave conversion element 10 comprising a second material having a second bandgap different from the first bandgap is formed on the second surface 6 of the substrate 2.
  • the process stage may be placed in well-loop, LDD-loop, source-drain-loop, or BEOL-loop.
  • the second electromagnetic wave conversion element 10 may be formed by epitaxial growth.
  • the step of forming the second electromagnetic wave conversion element 10 may comprise a sub-step of forming a buffer layer 11 comprising the first material and/or the second material, and a sub-step of forming the second electromagnetic wave conversion element 10 comprising the second material on the buffer layer 11.
  • the buffer layer 11 and the second electromagnetic wave conversion element 10 may be at least partially embedded in a recess disposed on the second surface 6 of the substrate 2.
  • the buffer layer 11 and the second electromagnetic wave conversion element 10 may be disposed to at least partially cover a fin portion disposed on the second surface 6 of the substrate 2.
  • the buffer layer 11 may be configured such that, closer to the second electromagnetic wave conversion element 10, the concentration of the second material is higher in a continuous manner or a stepped manner. Such a configuration may be obtained by varying a supply ratio between the first material and the second material from the deposition sources in a continuous manner or a stepped manner during depositing the buffer layer 11.
  • the buffer layer 11 may have a constant concentration ratio between the first material and the second material, but may be configured such that, closer to the second electromagnetic wave conversion element 10, the doping concentration is higher.
  • the first material may be silicon, and the second material may be SiGe, germanium, InGaAs, GaAs, a III-V material, quantum dots, an organic material, an inorganic material, or other radiation sensitive materials, or any combinations thereof.
  • the first material may be silicon, and the second material may be germanium.
  • the first electromagnetic wave conversion element 8 and the second electromagnetic wave conversion element 10 may be appropriately doped to have photosensitivity for visible light and SWIR light, respectively.
  • an insulation film 1712 such as an interlayer insulation film, and metal layers 1713 such as wirings may be formed on the second surface 6 of the substrate 2.
  • the metal layer 1713 may be, for example, wirings for the readout transistors 30.
  • the metal layer 1713 may be, for example, a reflection layer for improving the optoelectronic conversion efficiency of the second electromagnetic wave conversion element 10 as described with reference to Figures 10 and 11.
  • the metal layer 1713 may be a bias electrode for applying a bias voltage to the second electromagnetic wave conversion element 10 as described with reference to Figure 13.
  • the first surface 4 of the substrate 2 may optionally be polished or grinded for thinning the substrate 2.
  • a support wafer 1715 or a wafer 1715 comprising an integrated circuit may be bonded on the side of the second surface 6 of the substrate 2.
  • a recess 1714 may optionally be disposed on the first surface 4 of the substrate 2 to overlap the second electromagnetic wave conversion element 10 in a plan view.
  • the recess 1714 may be a light condensing element for condensing SWIR light to the second electromagnetic wave conversion element 10.
  • a first DTI 12 and a second DTI 36 may be formed from the first surface 4 of the substrate 2 toward the second surface 6.
  • the first DTI 12 may at least partially surround the first electromagnetic wave conversion element 8 and the second electromagnetic wave conversion element 10 in a plan view.
  • the first DTI 12 may be connected to the STIs 1711 to form the tapered portion 1011.
  • the tapered portion 1011 may be a light condensing element for condensing SWIR light to the second electromagnetic wave conversion element 10.
  • a grid structure 16, an insulation film 1715, and a micro lens 14 may be disposed on the first surface 4 of the substrate 2.
  • Figure 18 shows a partial cross-sectional diagram of a solid-state imaging device array comprising a plurality of solid-state imaging devices 1 according to some embodiments of the present invention.
  • the second side 6 of the substrate 2 of the solid-state imaging devices 1 may be bonded to an integrated circuit chip 1801 for controlling the solid-state imaging devices 1 and processing signals from the solid-state imaging devices 1.
  • Figure 19 shows perspective diagrams of image sensors 1901 to 1905 comprising a solid-state imaging device array according to some embodiments of the present invention.
  • the image sensor 1901 may comprise a pixel array 1911, a control circuit 1921, and a logic circuit 1931 integrated on one chip.
  • the image sensor 1902 may comprise a first chip on which a pixel array 1912 and a control circuit 1922 are integrated, and a second chip stacked on the first chip and comprising a logic circuit 1932.
  • the image sensor 1903 may comprise a first chip comprising a pixel array 1913, and a second chip stacked on the first chip and on which a control circuit 1923 and a logic circuit 1933 are integrated.
  • the image sensor 1904 may comprise a first chip comprising a pixel array 1914, a second chip comprising a memory circuit 1944, and a third chip on which a control circuit 1924 and a logic circuit 1934 are integrated.
  • the first, second, and third chips may be stacked.
  • the image sensor 1905 may comprise a first chip comprising a pixel array 1915, a second chip comprising a pixel circuit 1955, and a third chip on which a control circuit 1925 and a logic circuit 1935 are integrated.
  • the first, second, and third chips may be stacked.
  • Figure 20 shows a block diagram of an image sensor 2000 such as an image sensor shown in Figure 19.
  • the image sensor 2000 may comprise: a lens 2002; a solid-state imaging device array 2009; a shutter 2003 disposed between the lens 2002 and the solid-state imaging device array 2009; a control circuit 2005 for controlling the solid-state imaging device array 2009 and the shutter 2003; a signal processing circuit 2006 for processing output signals from the solid-state imaging device array 2009; a monitor 2007 for displaying an image processed and output by the signal processing circuit 2006; and a memory 2008 for storing an image processed and output by the signal processing circuit 2006.
  • the solid-state imaging devices described above may be applied to various fields including, for example, sports, beauty care, security, home appliances, agriculture, entertainment, transportation, and medical, treatment, and health care as shown in Figure 21.
  • the solid-state imaging devices described above may be used as external monitor sensors of a vehicle.
  • Solid-state imaging device 1001 to 1005, 1101 to 1105, 1201 to 1206, 1301 to 1304, 1401 to 1405, 1601 and 1602, and 1701: Solid-state imaging device;
  • Sub-buffer layer Sub-buffer layer

Abstract

The present invention provides an image apparatus, comprising: a substrate having a first surface, on which an electromagnetic wave impinges and a second surface opposite to the first surface; a first electromagnetic wave conversion element formed in the substrate and composed of a first material having a first bandgap; a second electromagnetic wave conversion element on a side of the second surface and composed of a second material having a second bandgap different from the first bandgap such that the second electromagnetic wave conversion element overlaps the first electromagnetic wave conversion element in a plan view; and a first deep trench isolation (DTI) extending in the substrate from the first surface toward the second surface and at least partially surrounding the first electromagnetic wave conversion element and the second electromagnetic wave conversion element in a plan view.

Description

Broadband Image Apparatus and Method of Fabricating the Same Technical Field
The present invention relates to an image apparatus and a method of fabrication thereof. More specifically, the present invention relates to a broadband radiation sensitive structure having at least two different materials and a method of fabrication thereof.
Background
Expanding a range of a radiation sensitive wavelength is highly demanded in the field of solid-state imaging devices. For instance, a short wave infrared (SWIR) spectral regime is attractive in terms of eye safety and less sensitive to weather conditions such as fog and dust. Therefore, an imaging device in such an SWIR spectrum range is in particular suitable for application to the field of the automobile technology.
Silicon used for conventional solid-state imaging devices has a large energy bandgap and therefore has a difficulty in detecting light having a wavelength in the SWIR spectrum range. Therefore, imaging devices operating in the SWIR spectrum range can be realized by utilizing a semiconductor material having a bandgap smaller than that of Si. Such a material different from Si may be prepared by a process using a single crystal bulk wafer which is different from an Si device wafer, or by depositing the material on a wafer having Si devices with selective epitaxial growth.
For example, United States Patent No. 10, 991, 745 proposes a device 2300 using an InGaAs material for a photosensitive layer as shown in Figure 23. An InGaAs layer 2304 is formed on a wafer or a chip 2302 by, for example, the epitaxial growth. The wafer or chip 2302 having the InGaAs layer 2304 is bonded between a different substrate 2306 on which a silicon pixel layer 2308 has been formed, and a further different substrate 2310 on which logic devices 2312 have been formed. However, such a device using an InGaAs layer has extremely large and thick InGaAs layer as a photosensitive layer, which results in high cost. In addition, the InGaAs process is not compatible with a conventional CMOS-based process. Therefore, such a device requires a complicated process as described above. As a result, the  application is limited.
For example, United States Patent No. 9, 954, 016 proposes a device 2400 employing a GeSi layer 2402 as a photosensitive layer, of which process is CMOS based as shown in Figure 24. However, an area of the GeSi layer as the photosensitive layer is significantly large. Since a dark current, which is a source of a noise, is proportional to the area of the GeSi layer, the dark current becomes very high. Such a large dark current has a large adverse impact on a signal-noise ratio (SNR) and a dynamic range (DR) .
For example, United States Patent No. 11,063,079 proposes a device 2500 having a Ge layer 2504 as a photosensitive layer located on a top of a Si layer 2502 having a pyramid shape as shown in Figure 25. The Si layer 2502 is configured to direct light to the small Ge layer 2504. However, such a structure is significantly different from a conventional CMOS imaging sensor structure, and thus it is difficult to implement a pixel device. Furthermore, the Ge layer 2504 is directly formed on the Si layer 2502. Therefore, the device 2500 has a large dislocation density resulting from a difference between the lattice constants of Si and Ge, and causing a high dark current.
Accordingly, a solid-state imaging device, which is compatible with conventional CMOS process that has a small dark current and that can detect light having a range of a SWIR spectrum, is desired.
Summary of the Invention
Means for Solving the Problem
A first embodiment according to the present invention provides an image apparatus, comprising:
a substrate having a first surface, on which an electromagnetic wave impinges and a second surface opposite to the first surface;
a first electromagnetic wave conversion element formed in the substrate and composed of a first material having a first bandgap;
a second electromagnetic wave conversion element on a side of the second surface and composed of a second material having a second bandgap different from the first band gap such that the second electromagnetic wave conversion element overlaps the first electromagnetic wave conversion element in a plan view; and
a first deep trench isolation (DTI) extending in the substrate from the first surface toward the second surface and at least partially surrounding the first electromagnetic wave conversion element and the second electromagnetic wave conversion element in a plan view.
According to the first embodiment of the present invention, since the first and second materials have bandgaps different from each other, the electromagnetic wave can be detected with wide dynamic range.
In the first embodiment of the present invention, the image apparatus may further comprise a buffer layer disposed between the first electromagnetic wave conversion element and the second electromagnetic wave conversion element and the buffer layer comprises the first material and the second material.
According to this aspect, the buffer layer may reduce the lattice mismatch to reduce or avoid dislocation defect.
In the first embodiment of the present invention, the buffer layer may be configured such that, closer to the second electromagnetic wave conversion element, a concentration of the second material is higher.
According to this aspect, the buffer layer may reduce the lattice mismatch to reduce or avoid dislocation defect.
In the first embodiment of the present invention, the image apparatus may further comprise a buffer layer disposed between the first electromagnetic wave conversion element and the second electromagnetic wave conversion element and including the second material, and
closer to the second electromagnetic wave conversion element, a doping concentration of the buffer layer may be configured to be higher.
According to this aspect, the buffer layer may reduce the lattice mismatch to reduce or avoid dislocation defect.
In the first embodiment of the present invention, the first material may be silicon, and
the second material may be selected from the group consisting of SiGe, germanium, InGaAs, GaAs, a III-V material, quantum dots, an organic material, an inorganic material, or other radiation sensitive material, or combinations thereof.
According to this aspect, electromagnetic wave can be detected with wide dynamic range.
In the first embodiment of the present invention, the first DTI may be configured to reflect electromagnetic wave impinging the image apparatus to condense the electromagnetic wave to the second electromagnetic wave conversion element.
According to this aspect, since the electromagnetic wave is gathered at the second electromagnetic wave conversion element, the detection efficiency is improved.
In the first embodiment of the present invention, the first DTI may be disposed on a periphery of the image apparatus in a plan view.
According to this aspect, the first DTI directs the electromagnetic wave to the second electromagnetic wave conversion element and functions as a device isolation.
In the first embodiment of the present invention, the first DTI may be disposed inward of the periphery of the image apparatus in a plan view.
According to this aspect, the first DTI directs the electromagnetic wave to the second electromagnetic wave conversion element at a higher efficiency.
In the first embodiment of the present invention, the image apparatus may further comprise a second DTI extending in the substrate from the first surface toward the second surface and at least partially surrounding the first DTI.
In the first embodiment of the present invention, the depth of the first DTI may be less than the thickness of the substrate.
In the first embodiment of the present invention, the depth of the first DTI may be equal to the thickness of the substrate.
In the first embodiment of the present invention, the depth of the second DTI may be less than the thickness of the substrate.
In the first embodiment of the present invention, the depth of the second DTI may be equal to the thickness of the substrate.
In the first embodiment of the present invention, the thickness of the first DTI in a plan view may be greater than the thickness of the second DTI in a plan view.
In the first embodiment of the present invention, the thickness of the first DTI in a plan view may be less than the thickness of the second DTI in a plan view.
In the first embodiment of the present invention, the first electromagnetic wave conversion element may have a polygonal shape in a plan view, and
the first DTI may be disposed on at least a part of at least two sides of the first  electromagnetic wave conversion element in a plan view.
According to this aspect, a footprint of the first DTI is reduced, and leads to miniaturization of the device.
In the first embodiment of the present invention, the first DTI may at least partially surround the first electromagnetic wave conversion element, and
a part of the second DTI may at least partially surround the first electromagnetic wave conversion element.
According to this aspect, footprints of the first and second DTIs are reduced, and lead to miniaturization of the device.
In the first embodiment of the present invention, the image apparatus may further comprise a light-condensing element configured to condense electromagnetic wave impinging the first surface to the second electromagnetic wave conversion element.
According to this aspect, since electromagnetic wave is gathered to the second electromagnetic wave conversion element, the detection efficiency is improved.
In the first embodiment of the present invention, the light-condensing element may be at least one recess disposed on the first surface.
In the first embodiment of the present invention, the light-condensing element may be a tapered portion of the first DTI disposed on the second surface such that, closer to the second surface, the thickness in a plan view may be larger toward the second electromagnetic wave conversion element.
In the first embodiment of the present invention, the light-condensing element may be a shallow trench isolation (STI) disposed inside of the first DTI in a plan view and at least partially surrounding the second electromagnetic wave conversion element.
In the first embodiment of the present invention, the light-condensing element may be a light-shielding layer comprising an aperture overlapping with the first electromagnetic wave conversion element.
In the first embodiment of the present invention, the light-condensing element may be a lens disposed on the first surface.
In the first embodiment of the present invention, the light-condensing element may be a metal layer disposed on the second surface and at least partially surrounding the second electromagnetic wave conversion element.
In the first embodiment of the present invention, an insulation film may be disposed on the second surface, and
the light-condensing element may be a metal layer in the insulation film such that the metal layer may overlap the second electromagnetic wave conversion element in a plan view.
In the first embodiment of the present invention, the light-condensing element may further comprise a metal layer in the insulation film such that the metal layer may at least partially surround the second electromagnetic wave conversion element in a plan view.
In the first embodiment of the present invention, the metal layer at least partially surrounding the second electromagnetic wave conversion element may electrically couple to the first electromagnetic wave conversion element by contacts, and
the contacts may at least partially surround the second electromagnetic wave conversion element.
According to this aspect, the electromagnetic wave is reflected on the metal layer toward the second electromagnetic wave conversion element to improve the light conversion efficiency.
In the first embodiment of the present invention, the metal layer overlapping the second electromagnetic wave conversion element may electrically couple to the metal layer at least partially surrounding the second electromagnetic wave conversion element by vias, and
the vias may at least partially surround the second electromagnetic wave conversion element.
According to this aspect, the electromagnetic wave is reflected on the metal layer toward the second electromagnetic wave conversion element to improve the light conversion efficiency.
In the first embodiment of the present invention, the light-condensing element may be a silicidation layer disposed on outer surfaces of the second electromagnetic wave conversion layer.
According to this aspect, the electromagnetic wave is reflected on the silicidation layer toward the second electromagnetic wave conversion element to improve the light conversion efficiency.
In the first embodiment of the present invention, the image apparatus may further comprise at least one third electromagnetic wave conversion element disposed in the substrate and at least partially between the first DTI and the second DTI, the third electromagnetic wave conversion element being composed of the first material having the first band gap.
According to this aspect, a volume of the electromagnetic wave conversion elements can be substantially increased and leads to an increase of the full-well capacity.
In the first embodiment of the present invention, the first electromagnetic wave conversion element may be coupled to the third electromagnetic wave conversion element.
In the first embodiment of the present invention, the first electromagnetic wave conversion element and the third electromagnetic wave conversion element may be coupled to different charge transfer gates disposed on the second surface, respectively.
In the first embodiment of the present invention, the first electromagnetic wave conversion element and the third electromagnetic wave conversion element may be coupled to one common charge transfer gate disposed on the second surface.
In the first embodiment of the present invention, the first electromagnetic wave conversion element may be coupled to a charge transfer gate disposed on the second surface, and
the charge transfer gate may extend into the substrate.
In the first embodiment of the present invention, the image apparatus may further comprise a bias electrode electrically coupled to the second electromagnetic wave conversion element and configured to apply a bias voltage to the second electromagnetic wave conversion element.
According to this aspect, a bias voltage can be applied to the second electromagnetic wave conversion element to substantially increase a full-well capacity and improve dynamic range.
In the first embodiment of the present invention, the image apparatus may further comprise:
an insulation film disposed on the second surface; and
a bias electrode in the insulation film, the bias electrode overlapping the  second electromagnetic wave conversion element in a plan view, and separated from the second electromagnetic wave conversion element.
According to this aspect, a bias voltage can be applied to the second electromagnetic wave conversion element to substantially increase a full-well capacity and improve dynamic range.
In the first embodiment of the present invention, the image apparatus may further comprise a fixed charge film at least partially covering the second surface and the second electromagnetic wave conversion element.
According to this aspect, a bias voltage can be applied to the second electromagnetic wave conversion element to substantially increase a full-well capacity and improve dynamic range.
In the first embodiment of the present invention, the image apparatus may further comprise an intrinsic stress film at least partially covering the second surface and the second electromagnetic wave conversion element.
According to this aspect, a stress can be applied to the second electromagnetic wave conversion element to substantially increase a full-well capacity and improve dynamic range.
In the first embodiment of the present invention, the second electromagnetic wave conversion element may have a circular, elliptic, or polygonal shape in a plan view.
In the first embodiment of the present invention, the second electromagnetic wave conversion element may be at least partially embedded in the first electromagnetic wave conversion element on the second surface.
According to this aspect, the second electromagnetic wave conversion element can be fabricated by known etching process.
In the first embodiment of the present invention, the first electromagnetic wave conversion element may comprise a fin portion protruded from the second surface, and
the second electromagnetic wave conversion element may at least partially cover the fin portion.
According to this aspect, the second electromagnetic wave conversion element can be fabricated by the known etching process.
In the first embodiment of the present invention, the second electromagnetic  wave conversion element may have a semicircular or polygonal shape in a cross-sectional view.
According to this aspect, the second electromagnetic wave conversion element can be fabricated by the known etching process.
In the first embodiment of the present invention, the STI may be disposed to be in contact with the second electromagnetic wave conversion element, and
the STI may be filled with an insulation material.
According to this aspect, the second electromagnetic wave conversion element can be fabricated by the known etching process.
A second embodiment of the present invention provides an image apparatus array comprising the image apparatuses according to the first embodiment of the present invention,
wherein the image apparatuses are arranged in an array, and
wherein the second electromagnetic wave conversion element of at least one image apparatus is shifted from a center of the image apparatus toward a center of the image apparatus array in a plan view.
According to the second embodiment of the present invention, the image apparatus array detecting electromagnetic wave having wide dynamic range can be obtained.
A third embodiment of the present invention provides an image sensor comprising any one of the image apparatus described above, or the image apparatus described above.
According to the third embodiment of the present invention, the image sensor array detecting electromagnetic wave having wide dynamic range can be obtained.
Another aspect of the third embodiment of the present invention provides a Time-of-Flight (TOF) sensor comprising any one of the image apparatus described above, or the image apparatus array described above.
Another aspect of the third embodiment of the present invention provides an electronic apparatus comprising any one of the image apparatus described above, or the image apparatus array described above.
A fourth embodiment of the present invention provides a method of manufacturing an image apparatus, comprising at least:
preparing a substrate having a first surface which electromagnetic wave  impinges and a second surface opposite to the first surface, the substrate comprising a first material having a first band gap;
forming a first electromagnetic wave conversion element in the substrate by doping;
forming a charge transfer gate coupled to the first electromagnetic wave conversion element on the second surface;
forming a second electromagnetic wave conversion element on the second surface, the second electromagnetic wave conversion element comprising a second material having a second bandgap different from the first bandgap by epitaxial growing; and
forming a first deep trench isolation (DTI) in the substrate from the first surface toward the second surface, the first DTI at least partially surrounding the first electromagnetic wave conversion element and the second electromagnetic wave conversion element in a plan view.
According to the fourth embodiment of the present invention, the image apparatus detecting electromagnetic wave with wide dynamic range can be obtained.
In the third embodiment of the present invention, the step of forming the second electromagnetic wave conversion element may comprise:
a sub-step of forming a buffer layer comprising the first material and/or the second material by epitaxial growing; and
a sub-step of forming the second electromagnetic wave conversion element composed of the second material on the buffer layer by epitaxial growing.
According to this aspect, the buffer layer may reduce the lattice mismatch to reduce or avoid dislocation defects.
In the third embodiment of the present invention, the buffer layer may be configured such that, closer to the second electromagnetic wave conversion element, a concentration of the second material may be higher.
According to this aspect, the buffer layer may reduce the lattice mismatch to reduce or avoid dislocation defects.
In the third embodiment of the present invention, the buffer layer may be configured such that, closer to the second electromagnetic wave conversion element, a concentration of doping may be higher.
According to this aspect, the buffer layer may reduce the lattice mismatch to  reduce or avoid dislocation defects.
In the third embodiment of the present invention, the first material may be silicon; and
the second material may be selected from the group consisting of SiGe, germanium, InGaAs, GaAs, a III-V material, quantum dots, an organic material, an inorganic material, or other radiation sensitive material, or combinations thereof.
According to this aspect, electromagnetic wave can be detected with wide dynamic range.
In the third embodiment of the present invention, the method may further comprise forming a second DTI at least partially surrounding the first DTI.
According to this aspect, since electromagnetic wave is gathered at the second electromagnetic wave conversion element, the detection efficiency is improved.
In the third embodiment of the present invention, the method may further comprise forming a light-condensing element configured to condense electromagnetic wave impinging the first surface to the second electromagnetic wave conversion element.
According to this aspect, since the electromagnetic wave is gathered to the second electromagnetic wave conversion element, the detection efficiency is improved.
Brief Explanation of the Figures
Figure 1 shows a cross-sectional diagram of a solid-state imaging device according to a first embodiment of the present invention.
Figure 2 shows a plan-view diagram of the solid-state imaging device of Figure 1.
Figure 3 shows a partially expanded diagram of the solid-state imaging device of Figure 1.
Figure 4 shows a circuit diagram of the solid-state imaging device according to the first embodiment of the present invention.
Figure 5 shows an imaging system having a plurality of solid-state imaging device arranged in an array.
Figure 6 shows cross-sectional diagrams of solid-state imaging devices according to some embodiments of the present invention.
Figure 7 shows plan-view diagrams of solid-state imaging devices according to some embodiments of the present invention.
Figure 8 shows plan-view diagrams of solid-state imaging devices according to some embodiments of the present invention.
Figure 9 shows cross-sectional diagrams of solid-state imaging devices according to some embodiments of the present invention.
Figure 10 shows cross-sectional diagrams of solid-state imaging devices according to some embodiments of the present invention.
Figure 11 shows cross-sectional diagrams of solid-state imaging devices according to some embodiments of the present invention.
Figure 12 shows cross-sectional diagrams of solid-state imaging devices according to some embodiments of the present invention.
Figure 13 shows cross-sectional diagrams of solid-state imaging devices according to some embodiments of the present invention.
Figure 14 shows plan-view diagrams of solid-state imaging devices according to some embodiments of the present invention.
Figure 15 shows expanded cross-sectional diagrams of the first and second electromagnetic wave conversion elements of solid-state imaging devices according to some embodiments of the present invention.
Figure 16 shows cross-sectional diagrams of solid-state imaging devices according to some embodiment of the present invention included in a solid-state imaging device array according to the present invention.
Figure 17 shows a method for fabricating a solid-state imaging device according to some embodiments of the present invention.
Figure 18 shows partial cross-sectional diagram of a solid-state imaging device array including solid-state imaging devices according to some embodiments of the present invention.
Figure 19 shows oblique-view diagrams of image sensors including a solid-state imaging device array according to some embodiments of the present invention.
Figure 20 shows a block diagram of an image sensor.
Figure 21 shows application examples of the solid-state imaging device according to the present invention.
Figure 22 shows an application example of the solid-state imaging device  according to the present invention.
Figure 23 shows a conventional solid-state imaging device.
Figure 24 shows a conventional solid-state imaging device.
Figure 25 shows a conventional solid-state imaging device.
Embodiments
The following disclosure provides many different embodiments or examples for implementing different features of the provided subject matter. Specific examples of elements and arrangements are described below to simplify the present disclosure. These are, of course, merely examples and are not intended to be limiting the invention. For example, the formation of a first feature over or on a second feature in the description that follows may include embodiments in which other features may be formed between the first and second features, such that the first and second features may not be in direct contact. In addition, the present disclosure may repeat reference numerals and/or letters in the various examples. This repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various embodiments and/or configurations discussed.
Figure 1 shows a cross-sectional diagram of an image apparatus, in particular a solid-state imaging device 1 according to a first embodiment of the present invention. Figure 2 shows a plan-view of the solid-state imaging device 1 of Figure 1. Figure 3 shows a partially-expanded diagram of the solid-state imaging device 1 of Figure 1. Figure 4 shows a circuit diagram of the solid-state imaging device 1. Figure 5 shows an imaging system 201 comprising a plurality of solid-state imaging devices 1 arranged in an array.
The solid-state imaging device 1 comprises a substrate 2 having a first surface 4 and a second surface 6 opposite to the first surface 4. The first surface 4 is an impinging surface which electromagnetic wave such as visible light and/or light having a short wave infrared (SWIR) wavelength impinges. A first electromagnetic wave conversion element 8 comprising a first material having a first bandgap is located in the substrate 2. A second electromagnetic wave conversion element 10 comprising a second material having a second bandgap different from the first bandgap is disposed on a side of the second surface 6 such that the second electromagnetic wave conversion element 10 overlaps the first electromagnetic wave  conversion element 8 in a plan view. In the present specification, the term of “in a plan view” generally means a direction seeing the substrate 2 along the direction perpendicular to the first surface 4 of the substrate 2, or a direction seeing the substrate 2 along the direction perpendicular to the second surface 6 of the substrate 2.
The solid-state imaging device 2 further comprises at least one first deep trench isolation (DTI) 12 extending into the substrate 2 from the first surface 4 toward the second surface 6 of the substrate 2. The first DTI 12 at least partially surrounds the first electromagnetic wave conversion element 8 and the second electromagnetic wave conversion element 10 in a plan view. The first DTI 12 may be formed, for example, by filling an insulation material in a trench formed on the substrate 2. In some embodiments, the second bandgap is smaller than the first bandgap. In some embodiments, the first electromagnetic wave conversion element 8 may have a sensitivity for visible light, and the second electromagnetic wave conversion element 10 may have a sensitivity for SWIR light. For example, the first material composing the first electromagnetic wave conversion element 8 may be a semiconductor material such as silicon. The second material composing the second electromagnetic wave conversion element 10 may be a material selected from the group including SiGe, germanium, InGaAs, a III-V material, quantum dots, an organic material, an inorganic material, and other radiation sensitive material, and any combinations thereof. In some embodiments, the first material composing the first electromagnetic wave conversion element 8 may be silicon, and the second material composing the second electromagnetic wave conversion element 10 may be germanium. The first electromagnetic wave conversion element 8 and the second electromagnetic wave conversion element 10 may be appropriately doped such that the first and second electromagnetic  wave conversion elements  8, 10 form photodiodes, respectively.
In some embodiments, the substrate 2 may be a p-type substrate. A portion of the first electromagnetic wave conversion element 8 closer to the first surface 4 of the substrate 2 may be n-doped. a portion of the first electromagnetic wave conversion element 8 closed to the second surface 6 of the substrate 2 may be n doped. The second electromagnetic wave conversion element 10 may be p+ doped.
Figure 3 shows an expanded view of the first electromagnetic wave conversion  element 8 and the second electromagnetic wave conversion element 10. A buffer layer 11 may be disposed between the first electromagnetic wave conversion element 8 and the second electromagnetic wave conversion element 10. The buffer layer 11 may be configured to reduce or prevent dislocation defects due to a lattice mismatch between the first electromagnetic wave conversion element 8 and the second electromagnetic wave conversion element 10. In some embodiments, the buffer layer 11 may comprise the first material composing the first electromagnetic wave conversion element 8 and the second material composing the second electromagnetic wave conversion element 10. The buffer layer 11 may be configured such that, closer to the first electromagnetic wave conversion element 8, the concentration of the first material is higher, and such that, closer to the second electromagnetic wave conversion element 10, the concentration of the second material is higher. The concentration ratio of the first material and the second material may be configured to vary in the buffer layer 11 in a stepped manner. Alternatively, the concentration ratio of the first material and the second material may be configured to continuously vary. Therefore, the lattice mismatch between the first electromagnetic wave conversion element 8 and the second electromagnetic wave conversion element 10 may be relaxed, which allows the dislocation defects to be reduced or prevented. The planar dimension of the buffer layer 11 and the second electromagnetic wave conversion element 10 may be, for example, in a range approximately between 0.005 μm and 1 μm.
In some of other embodiments, the buffer layer 11 may comprise only the first material, only the second material, or the first material and the second material at a constant concentration ratio across the entire buffer layer 11. In such embodiments, the doping concentration of the buffer layer 11 may be configured to vary from the first electromagnetic wave conversion element 8 to the second electromagnetic wave conversion element 10 in a continuous or stepped manner. Therefore, the lattice mismatch and/or stresses between the first electromagnetic wave conversion element 8 and the second electromagnetic wave conversion element 10 may be relaxed, which allows dislocation defects to be reduced or prevented.
In some embodiments, the buffer layer 11 and the second electromagnetic wave conversion element 10 may be formed by (111) facet growth. Such growth may elastically relax strained layers without forming defects. Furthermore, the structure  may grow in a free space along at least two directions, which also allows the elastic relaxation.
In some embodiments, a micro-lens 14 for condensing impinging light and a grid structure 16, which is a light-shielding layer preventing stray light from entering adjacent imaging devices, are disposed on the first surface 4 of the substrate 2. The grid structure 16 may be disposed along a periphery of the solid-state imaging device 1.
In some embodiments, a floating diffusion region 18 and readout transistors 30 for reading out charge signals from the first electromagnetic wave conversion element 8 and the second electromagnetic wave conversion element 10 may be disposed on the second surface 6 of the substrate 2. The readout transistors 30 may comprise a charge transfer gate 20, a source follower device 22, a row select device 24, a reset device 26, and a dual conversion gain device 28. As shown in Figure 4, the first electromagnetic wave conversion element 8 and/or the second electromagnetic wave conversion element 10 may be coupled to the floating diffusion region 18 via the charge transfer gate 20. The floating diffusion region 18 may be coupled to a gate of the source follower device 22. A drain of the source follower device 22 may be coupled to a device power source 32, and a source of the source follower device 22 may be coupled to a drain of the row select device 24. A source of the row select device 24 may be coupled to a column output line 34. The reset device 26 may be disposed between the device power source 32 and the floating diffusion region 18. Optionally, the dual conversion gain device 28 may be disposed between the reset device 26 and the floating diffusion region 18.
An operation of the solid-state imaging device 1 having such a configuration will be discussed. Light impinges the first surface 4 of the substrate 2 of the solid-state imaging device 1 via the micro-lens 14. If the impinging light has a wavelength of visible light, optoelectronic conversion may occur in the first electromagnetic wave conversion element 8 and may cause charges. If the impinging light has, for example, a wavelength in the range of SWIR, the light may not be absorbed in the first electromagnetic wave conversion element 8, and may be reflected on the first DTI 12 toward the second surface 6 of the substrate 2. The first DTI 12 is configured to at least partially surround the first electromagnetic wave conversion element 8 and the second electromagnetic wave conversion element 10 in a plan view.  Therefore, the light reflected by the first DTI 12 may reach the second surface 6 and be condensed to the second electromagnetic wave conversion element 10. The light reaching the second electromagnetic wave conversion element 10 may cause charges by optoelectronic conversion.
The charges caused in the second electromagnetic wave conversion element 10 by the optoelectronic conversion may be transferred to the floating diffusion 18 by turning the charge transfer gate 20 on. Since the floating diffusion region 18 is coupled to the gate of the source follower device 22, the amount of the charges transferred to the floating diffusion region 18 may be gained by the source follower device 22. When the row select device 24 is turned on, a signal gained in response to the amount of the charges transferred to the floating diffusion region 18, for example, a gained current flows through the column output line 34. The amount of light impinging the second electromagnetic wave conversion element 10 can be measured by detecting the signal output to the column output line 34.
More specifically, a signal is obtained by carrying out a correlating double sampling (CDS) which uses a difference between a reset level and a signal level. The reset level is sampled after the reset operation and before the charge transfer gate 20 is turned on, and the signal level is sampled after the charge transfer gate 20 is turned off and before the row select device 24 is turned off.
When the readout is finished, the reset device 26 may be turned on to reset the floating diffusion region 18.
Alternatively, the full-well capacity may be optimized by the dual conversion gain device 28 to improve the dynamic range.
Although not shown in the figure, a similar circuit for readout of the first electromagnetic wave conversion element 8 may be provided in some embodiments. Alternatively, the readout circuit for the first electromagnetic wave conversion element 8 may share at least one of the components of the readout circuit for the second electromagnetic wave conversion element 10. Such a configuration may allow the solid-state imaging device 1 to have sensitivity for both of the visible light and the SWIR light, which leads to a broad band response.
In another embodiment, instead of reading out the data as a frame, an “event driven” type of an image sensor may be implemented by using the solid state imaging device 100 according to the present invention. The event driven type of the image  sensor may output data in an asynchronous way, in other words, at any time in response to changes in the intensity of electromagnetic radiation incident on one or more pixels. Specifically, for example, if pixel charges generated by electromagnetic radiation incident on one or more photodiodes (PD) (or one or more pixels) and stored in the one or more photodiodes (PD) exceed a predetermined threshold value, an event of an intensity of the electromagnetic radiation exceeding the threshold value or data representing the intensity of the electromagnetic radiation may be output along with coordinates of the one or more pixels (for example, x and y coordinates in the pixel array) and timing information.
In some embodiments, photodiodes may be used in time-of-flight (TOF) applications. There are two types of TOF. One is indirect TOF sensors which send out continuous and modulated light and measure a phase of reflected light to calculate a distance to an object. The other is direct TOF sensors which send out short pulses of light that last just a few nanoseconds and then measure time which it takes for some of the emitted light to be reflected back. A direct TOF sensor may have a configuration referred to as a single photon avalanche diode (SPAD) . A pixel having such a photodiode comprises a high electric field region in the pixel. Repeating a process in which electrons and holes generated by the photoelectron conversion are accelerated by a strong electric field to cause atoms to collide in the pixels and generate further electrons and holes, and electron avalanche amplification generating a large amount of electrons and holes finally occurs. Therefore, the SPAD can generate a large amount of pixel charges even if the intensity of an incident electromagnetic wave is small, and therefore can contribute to high sensitivity of imaging and a high accuracy of distance measurement using the image sensor.
As shown in Figure 5, an imaging system 201 using the solid-state imaging devices 1 according to the present invention may be provided. The imaging system 201 may comprise a pixel array 209 comprising the solid-state imaging devices 1 arranged in an array, a control circuit 205 for controlling the pixel array 209, bit lines 204 each coupled to the column output line 34 of the solid-state imaging devices 1 in each column of the pixel array 209, and a readout circuit 210 to which the bit lines 204 are coupled, and a signal processing circuit 206 to which output from the readout circuit 210 is coupled. As described above, signals due to light impinging the solid-state imaging devices 1 are read out by the readout circuit via the bit lines 204.  Therefore, the control circuit 205 may carry out readout scanning for each row, and the signal processing circuit 206 may process the readout signals to obtain a two-dimensional image.
Figure 6 shows cross-sectional diagrams of solid-state imaging devices 601 to 607 according to some embodiments of the present invention.
As shown in Figure 6 (A) , the first DTI 12 may be disposed at a periphery of the solid-state imaging device 601 in a plan view. In such a configuration, the first DTI 12 realizes device isolation from adjacent solid-state imaging devices as well as the first DTI 12 directs impinging light to the second electromagnetic wave conversion element 10. Therefore, cross-talk due to the adjacent solid-state imaging devices may be reduced. Furthermore, the volume of the first electromagnetic wave conversion element 8 may be maximized to increase the full-well capacity. In Figure 6 (A) , since the depth of the first DTI 12 is smaller than the thickness of the substrate 2, the first DTI 12 does not reach the second surface 6. As such, a DTI having a depth smaller than the thickness of the substrate may also be referred to as a partial depth DTI. The partial depth DTI may, for example, reduce the width of the DTI. Furthermore, since the DTI is not exposed on the second surface 6 of the substrate 2, the degree of freedom of designs of the readout transistors and other components and wirings disposed on the second surface 6 may be increased. However, although not shown in the figure, the depth of the first DTI 12 may be equal to the thickness of the substrate 2. In this case, the first DTI 12 reaches the second surface 6 to realize complete device isolation.
Alternatively, as shown in Figure 6 (B) , the first DTI 12 may be disposed inward of the periphery of the solid-state imaging device 1 in a plan view. In such a configuration, since the first DTI 12 may increase the impinging light condensed to the second electromagnetic wave conversion element 10, the optoelectronic conversion efficiency (or the quantum efficiency) of the second electromagnetic wave conversion element 10 may be improved. In Figure 6 (B) , the depth of the first DTI 12 is smaller than the thickness of the substrate 2, and therefore the first DTI 12 does not reach the second surface 6. However, although not shown in the figure, the depth of the first DTI 12 may be equal to the thickness of the substrate 2. In this case, the first DTI 12 may reach the second surface 6 to realize complete device isolation.
Alternatively, as shown in Figures 6 (C) to 6 (G) , in addition to the first DTI 12  disposed inward of the periphery of each of solid-state imaging devices 603 to 607 in a plan view, each of the solid-state imaging devices 603 to 607 may further comprise a second DTI 36 disposed at the periphery of each of the solid-state imaging devices 603 to 607 and at least partially surrounding the first DTI 12 in a plan view. Both the first DTI 12 and the second DTI36 may be partial depth DTIs of which depths are smaller than the thickness of the substrate, or may be complete DTIs of which depths are equal to the thickness of the substrate.
For example, since the depth of the first DTI 12 of the solid-state imaging device 603 shown in Figure 6 (C) is smaller than the thickness of the substrate 2, the first DTI 12 does not reach the second surface 6. On the other hand, the depth of the second DTI 36 is equal to the thickness of the substrate 2, the second DTI 36 may reach the second surface 6.
For example, since the depth of the first DTI 12 of the solid-state imaging device 604 shown in Figure 6 (D) is equal to the thickness of the substrate 2, the first DTI 12 may reach the second surface 6. On the other hand, the depth of the second DTI 36 is smaller than the thickness of the substrate 2, the second DTI 36 does not reach the second surface 6.
For example, since the depths of the first DTI 12 and the second DTI 36 of the solid-state imaging device 605 shown in Figure 6 (E) are smaller than the thickness of the substrate 2, the first DTI 12 and the second DTI 36 may not reach the second surface 6.
For example, since the width of the first DTI 12 of the solid-state imaging device 606 shown in Figure 6 (F) in a plan view may be larger than the width of the second DTI 36. In Figure 6 (F) , the depth of the first DTI 12 is equal to the thickness of the substrate 2, and the depth of the second DTI 36 is smaller than the thickness of the substrate 2. However, the depths of the first DTI 12 and the second DTI 36 are not limited to those shown in Figure 6 (F) .
For example, since the width of the first DTI 12 of the solid-state imaging device 607 shown in Figure 6 (G) in a plan view may be smaller than the width of the second DTI 36. In Figure 6 (G) , the depth of the first DTI 12 is equal to the thickness of the substrate 2, and the depth of the second DTI 36 is smaller than the thickness of the substrate 2. However, the depths of the first DTI 12 and the second DTI 36 are not limited to those shown in Figure 6 (G) .
Figure 7 shows plan-view diagrams of solid-state imaging devices 701 to 706 according to some embodiments of the present invention, seen from the side of the second surface 6 of the substrate 2. The first electromagnetic wave conversion element 8 of each of the solid-state imaging devices 701 to 706 shown in Figure 7 has a polygonal shape in a plan view. The shape of the first electromagnetic wave conversion element 8 may be a regular polygon or a non-regular polygon.
The first DTI 12 of each of the solid-state imaging devices 701 to 706 may be disposed to at least partially surround the first electromagnetic wave conversion element 8 having a polygonal shape. The first DTI 12 may be disposed at along at least parts of at least two sides of the first electromagnetic wave conversion element 8 having a polygonal shape.
The first DTI 12 of each of the solid-state imaging device 701 to 706 may at least partially separate the first electromagnetic wave conversion element 8 from at least one of the floating diffusion region 18, the source follower device 22, the row select device 24, the reset device 26, and the dual conversion gain device 28.
For example, the shape of the first electromagnetic wave conversion element 8 of the solid-state imaging device 701 shown in Figure 7 (A) is a square shape in a plan view. The first DTI 12 may be disposed along three sides of the first electromagnetic wave conversion element 8. The first DTI 12 may not be disposed along one side of the first electromagnetic wave conversion element 8. The first DTI 12 may at least partially separate the first electromagnetic wave conversion element 8 from the floating diffusion region 18, the source follower device 22, and the row select device 24. On the other hand, the first DTI 12 may not separate the first electromagnetic wave conversion element from the reset device 26 and the dual conversion gain device 28.
For example, the shape of the first electromagnetic wave conversion element 8 of the solid-state imaging device 702 shown in Figure 7 (B) is a square shape or a rectangular shape in a plan view. The first DTI 12 may be disposed along two sides of the first electromagnetic wave conversion element 8 facing each other. The first DTI 12 may not be disposed along the other two sides of the first electromagnetic wave conversion element 8 facing each other. The first DTI 12 may at least partially separate the first electromagnetic wave conversion element 8 from the floating diffusion region 18, the source follower device 22, and the row select device 24. On  the other hand, the first DTI 12 may not separate the first electromagnetic wave conversion element 8 from the reset device 26 and the dual conversion gain device 28.
For example, the shape of the first electromagnetic wave conversion element 8 of the solid-state imaging device 703 shown in Figure 7 (C) is a square shape in a plan view. The first DTI 12 may be disposed along parts of four sides of the first electromagnetic wave conversion element 8. Therefore, the first DTI 12 is composed of four DTIs which are not connected with each other, and at least partially surrounds the first electromagnetic wave conversion element 8. The first DTI 12 may at least partially separate the first electromagnetic wave conversion element 8 from the source follower device 22, the reset device 26, and the dual conversion gain device 28. On the other hand, the first DTI 12 may not separate the first electromagnetic wave conversion element 8 from the floating diffusion region 18 and the row select device 24.
For example, the shape of the first electromagnetic wave conversion element 8 of the solid-state imaging device 704 shown in Figure 7 (D) is a square shape in a plan view. The first DTI 12 may be disposed along parts of four sides of the first electromagnetic wave conversion element 8. Therefore, the first DTI 12 is composed of four DTIs which are not connected with each other, and at least partially surrounds the first electromagnetic wave conversion element 8. The first DTI 12 may at least partially separate the first electromagnetic wave conversion element 8 from the floating diffusion region 18, the source follower device 22, the row select device 24, the reset device 26, and the dual conversion gain device 28.
For example, the shape of the first electromagnetic wave conversion element 8 of the solid-state imaging device 705 shown in Figure 7 (E) is an octagonal shape in a plan view. The first DTI 12 may be disposed along seven sides of the first electromagnetic wave conversion element 8. The parts of the first DTI 12 disposed along sides adjacent to a side, along which the first DTI 12 is not disposed, are extended and connected with each other. Therefore, the first DTI 12 may separate the first electromagnetic wave conversion element 8 from the floating diffusion region 18, the source follower device 22, the row select device 24, the reset device 26, and the dual conversion gain device 28.
For example, the shape of the first electromagnetic wave conversion element 8 of the solid-state imaging device 706 shown in Figure 7 (F) is an octagonal shape in a  plan view. The first DTI 12 may be disposed along seven sides of the first electromagnetic wave conversion element 8. The parts of the first DTI 12 disposed along sides adjacent to a side, along which the first DTI 12 is not disposed, are not connected with each other. The first DTI 12 may separate the first electromagnetic wave conversion element 8 from the source follower device 22, the row select device 24, the reset device 26, and the dual conversion gain device 28. The first DTI 12 may not separate the first electromagnetic wave conversion element 8 from the floating diffusion region 18.
Figure 8 shows plan-view diagrams of solid-state imaging devices 801 to 804 according to some embodiments of the present invention seen from the side of the second surface 6 of the substrate 2. The first DTI 12 of each of the solid-state imaging devices 801 to 804 shown in Figure 8 at least partially surrounds the first electromagnetic wave conversion element 8, and a part of the second DTI 36 at least partially surrounds the first electromagnetic wave conversion element 8. Therefore, the first electromagnetic wave conversion element 8 may be at least partially surrounded by the first DTI 12 and the second DTI 36. Different from the case in which only the first DTI 21 surrounds the first electromagnetic wave conversion element 8, the planar area of the first DTI 12 may be reduced. Therefore, for example, the volume of the first electromagnetic wave conversion element 8 may be increased to improve the dynamic range.
For example, the first DTI 12 of the solid-state imaging device 801 shown in Figure 8 (A) , is connected to the second DTI 36 to surround the first electromagnetic wave conversion element 8. The first DTI 12 and the part of the second DTI 36 may collectively have a polygonal shape such as a square shape in a plan view.
For example, the first DTI 12 the solid-state imaging device 802 shown in Figure 8 (B) is connected to the second DTI 36 to surround the first electromagnetic wave conversion element 8. The first DTI 12 and the part of the second DTI 36 may collectively have a polygonal shape such as a pentagonal shape in a plan view. The shape of the first DTI 12 shown in Figure 8 (B) , of which one vertex is beveled, may increase a spatial efficiency of the solid-state imaging device 802. Therefore, a configuration shown in Figure 8 (B) may improve the degree of freedom of the design of the readout transistors and may provide miniaturization of the solid-state imaging device 802.
For example, the first DTI 12 of the solid-state imaging device 803 shown in Figure 8 (C) is connected to the second DTI 36 to surround the first electromagnetic wave conversion element 8. The first DTI 12 and the part of the second DTI 36 may collectively have a polygonal shape such as a square shape in a plan view. However, the DTI 12-1 and the DTI 12-2, which compose the sides of the first DTI 12, are not connected to each other. Therefore, the first DTI 12 and the second DTI 36 partially surround the first electromagnetic wave conversion element 8.
The first DTI 12 and the part of the second DTI 36 of the solid-state imaging device 804 shown in Figure 8 (D) surround the first electromagnetic wave conversion element 8. The first DTI 12 and the part of the second DTI 36 may collectively have a polygonal shape such as a square shape in a plan view. However, the DTI 12-1 and the DTI 12-2, which compose the sides of the first DTI 12, are not connected to each other. Furthermore, the DTI 12-1 and the DTI12-2 are not connected to the second DTI 36. Therefore, the first DTI 12 and the second DTI 36 may partially surround the first electromagnetic wave conversion element 8.
Figure 9 shows cross-sectional diagrams of each of solid- state imaging devices  901 and 902 according to some embodiments of the present invention. Each of the solid- state imaging devices  901 and 902 shown in Figure 9 further comprise a light condensing element configured to condense the SWIR light impinging the first surface 4 to the second electromagnetic wave conversion element 10. Light condensing elements having various shape may be applied. Condensing light to the second electromagnetic wave conversion element 10 may increase the quantum efficiency, for example, the optoelectronic conversion efficiency.
For example, the solid-state imaging device 901 shown in Figure 9 (A) may comprise at least one recess 911 disposed on the first side 4 of the substrate 2 as a light condensing element. The recess 911 may be, for example, filled with a transparent insulation material. The recess 911 may be disposed to overlap the second electromagnetic wave conversion element 10 in a plan view. The cross-section of the recess 911 may have, for example, a triangle shape of which vertex is disposed in the substrate 2. The recess 911 may reflect, refract, and/or diffract SWIR light impinging the first surface 4 to condense the SWIR light to the second electromagnetic wave conversion element 10.
For example, the solid-state imaging device 902 shown in Figure 9 (B) may  comprise at least one recess 912 disposed on the first surface 4 of the substrate 2 as a light condensing element. Figure 9 (B) shows a plurality of recesses 912. The recesses 912 may be, for example, filled with a transparent insulation material. The cross section of the recesses 912 are for example rectangular. At least one of the recesses 912 is disposed to overlap the second electromagnetic wave conversion element 10 in a plan view. The other recesses 912 may be disposed to, for example, surround the second electromagnetic wave conversion element 10 in a plan view. The recesses 912 may reflect, refract, and/or diffract SWIR light impinging the first surface 4 to condense the SWIR light to the second electromagnetic wave conversion element 10.
Figure 10 shows cross-sectional diagrams of solid-state imaging devices 1001 to 1005 according to some embodiments of the present invention. Each of the solid-state imaging device 1001 to 1005 shown in Figure 10 may further comprise a light condensing element configured to condense SWIR light impinging the first surface 4 to the second electromagnetic wave conversion element 10. Light condensing elements having various shape may be applied. Condensing light to the second electromagnetic wave conversion element 10 may increase the quantum efficiency, for example, the optoelectronic conversion efficiency.
For example, the first DTI 12 of the solid-state imaging device 1001 shown in Figure 10 (A) extends from the first surface 4 of the substrate 2 to the second surface 6. The end of the first DTI 12 on the side of the second surface 6 comprises a taper portion 1011 having a width which becomes larger toward the second surface 6 in a cross-sectional view. The taper portion 1011 extends toward the second electromagnetic wave conversion element 10 in a plan view closer to the second surface 6. The taper portion 1011 may function as a light condensing element which reflect and direct the SWIR light to the second electromagnetic wave conversion element 10.
For example, the solid-state imaging device 1002 shown in Figure 10 (B) may comprise a shallow trench isolation (STI) 1012 disposed inward of the first DTI 12 in a plan view to at least partially surround the second electromagnetic wave conversion element 10. The STI 1012 may be a trench extending from the second surface 6 toward inside of the substrate 2 and filled with an insulation material or the like. The STI 1012 may function as a light condensing element which reflects SWIR light  to condense the SWIR light to the second electromagnetic wave conversion element 10.
For example, the solid-state imaging device 1003 shown in Figure 10 (C) may comprise a grid structure 16 which is a light shielding layer disposed on the first surface 4 of the substrate 2. The grid structure 16 may comprise an aperture 1013 extended inward of the first DTI 21 and overlapping the first electromagnetic wave conversion element 8 in a plan view. The SWIR light is collimated when passing the aperture 1013 and is condensed to the second electromagnetic wave conversion element 10. In addition, a reflected electromagnetic wave passing through the substrate 2 from the direction of the surface 6 may be reflected by the bottom surface of the grid structure 16 and be directed to the second electromagnetic wave conversion element 10. Therefore, the aperture 1013 may function as a light condensing element.
For example, the solid-state imaging device 1004 shown in Figure 10 (D) may comprise a micro-lens 1014 on the first surface 4 of the substrate 2. The micro-lens 1014 may overlap the first electromagnetic wave conversion element 8 in a plan view. The micro-lens 1014 may function as a light condensing element refracting SWIR light to condense the SWIR light to the second electromagnetic wave conversion element 10.
For example, the solid-state imaging device 1005 shown in Figure 10 (E) may comprise a reflection layer 1015 disposed over the second surface 6 of the substrate 2. The reflection layer 1015 may be made by a gate of a device or a metal-0 layer. The reflection layer 1015 may at least partially surround the second electromagnetic wave conversion element 10 in a plan view. SWIR light not impinging the second electromagnetic wave conversion element 10 and reaching the second surface 6 of the substrate 2 may be reflected on the reflection layer 1015 back to the substrate 2. The reflected SWIR light may be reflected on the first surface 4 of the substrate 2 and/or the first DTI 12 to impinge the second electromagnetic wave conversion element 10. Therefore, the reflection layer 1015 may function as a light condensing element.
Figure 11 shows cross-sectional diagrams of solid-state imaging devices 1101 to 1105 according to some embodiments of the present invention. Each of the solid-state imaging devices 1101 to 1105 shown in Figure 11 may further comprise a light condensing element configured to condense SWIR light impinging the first surface 4  to the second electromagnetic wave conversion element 10. Light condensing elements having various shape may be applied. Condensing light to the second electromagnetic wave conversion element 10 may increase the quantum efficiency, for example, the optoelectronic conversion efficiency.
For example, the solid-state imaging device 1101 shown in Figure 11 (A) may comprise an insulation film 1108 disposed on the second surface 6 of the substrate 2. At least one metal layer 1111 is disposed in the insulation film 1108. The metal layer 1111 may be configured to be separated from the second electromagnetic wave conversion element 10 and configured to overlap the second electromagnetic wave conversion element 10 in a plan view. The metal layer 1111 may reflect light passing through the substrate 2 without impinging the second electromagnetic wave conversion element 10 back to the substrate 2 and/or the second electromagnetic wave conversion element 10. Therefore, the metal layer 1111 may function as a light condensing element. The metal layer 1111 may function as wirings for reading signals as well as functioning as the light condensing element.
For example, the solid-state imaging device 1102 shown in Figure 11 (B) may comprise an insulation film 1108 dispose on the second surface 6 of the substrate 2. At least one metal layer 1112 is disposed in the insulation film 1108. The metal layer 1112 may be configured to be separated from the second electromagnetic wave conversion element 10. A first metal layer 1112-1 among the metal layers 1112 may be disposed to overlap the second electromagnetic wave conversion element 10 in a plan view. A second metal layer 1112-2 among the metal layers 1112 may be disposed to at least partially surround the second electromagnetic wave conversion element 10 in a plan view. The first metal layer 1112-1 may be disposed on a level different form the second metal layer 1112-2, or may be disposed on the same level as the second metal layer 1112-2. The first metal layer 1112-1 and/or the second metal layer 1112-2 may reflect light passing through the substrate 2 without impinging the second electromagnetic wave conversion element 10 back to the substrate 2 and/or the second electromagnetic wave conversion element 10. Therefore, the first metal layer 1112-1 and/or the second metal layer 1112-2 may function as a light condensing element. The first metal layer 1112-1 and/or the second metal layer 1112-2 may function as wirings for reading signals as well as function as a light condensing element.
For example, the solid-state imaging device 1103 shown in Figure 11 (C) may comprise a reflection layer 1113 disposed on an outer surface of the second electromagnetic wave conversion element 10 and at least partially surrounding the second electromagnetic wave conversion element 10. The reflection layer 1113 may be, for example, a silicidation layer. The reflection layer 1113 may reflect SWIR layer impinging but passing through the second electromagnetic wave conversion element 10 back to the second electromagnetic wave conversion element 10. Therefore, the reflection layer 1113 may function as a light condensing element.
For example, the solid-state imaging device 1104 shown in Figure 11 (D) may comprise an insulation film 1108 disposed on the second surface 6 of the substrate 2. At least one metal layer 1114 is disposed in the insulation film 1108. The metal layers 1114 are separated from the second electromagnetic wave conversion element 10. A first metal layer 1114-1 among the metal layers 1114 may be disposed to overlap the second electromagnetic wave conversion element 10 in a plan view. A second metal layer 1114-2 among the metal layers 1114 may be disposed to at least partially surround the second electromagnetic wave conversion element 10 in a plan view. The second metal layer 1114-2 may be electrically coupled to the first electromagnetic wave conversion element 8 and/or the second electromagnetic wave conversion element 10 via contacts 1124. The contacts 1124 may be disposed to at least partially surround the second electromagnetic wave conversion element 10. Therefore, the second metal layer 1114-2 and the contacts 1124 may function as a fixing surface pinning layer potential to ground or negative bias in case of the n-type photodiode. The first metal layer 1114-1 may be disposed at a level different from a lever of the second metal layer 1114-2, or may be disposed at the same level as the level of the second metal layer 1114-2. The first metal layer 1114-1 and/or the second metal layer 1114-2 reflects light passing through the substrate 2 without impinging the second electromagnetic wave conversion element 10 back to the substrate 2 and/or the second electromagnetic wave conversion element 10. The contacts 1124 may direct the SWIR light reflected by the first metal layer 1114-1 and/or the second metal layer 1114-2 to the second electromagnetic wave conversion element 10. Therefore, the first metal layer 1114-1, the second metal layer 1114-2, and the contacts 1124 may function as a light condensing element.
For example, the solid-state imaging device 1105 shown in Figure 11 (E)  comprises an insulation film 1108 disposed on the second surface 6 of the substrate 2. At least one metal layer 1115 is disposed in the insulation layer 1108. The metal layers 1115 are separated from the second electromagnetic wave conversion element 10. A first metal layer 1115-1 among the metal layers 1115 may be disposed to overlap the second electromagnetic wave conversion element 10 in a plan view. A second metal layer 1115-2 among the metal layers 1115 may be disposed to at least partially surround the second electromagnetic wave conversion element 10 in a plan view. The first metal layer 1115-1 may be electrically coupled to the second metal layer 1115-2 through vias 1125. The vias 11125 may be disposed to at least partially surround the second electromagnetic wave conversion element 10 in a plan view. The first metal layer 1115-1 may be disposed at a level different from the level of the second metal layer 1115-2. The first metal layer 1115-1 and/or the second metal layer 1115-2 reflect light passing through the substrate 2 without impinging the second electromagnetic wave conversion element 10 back to the substrate 2 and/or the second electromagnetic wave conversion element 10. The vias 1125 may direct the SWIR light reflected by the first metal layer 1115-1 and/or the second metal layer 1115-2 to the second electromagnetic wave conversion element 10. Therefore, the first metal layer 1115-1, the second metal layer 1115-2, and the vias 1125 may function as a light condensing element.
Figure 12 shows cross-sectional diagrams of solid-state imaging devices 1201 to 1206 according to some embodiments of the present invention.
For example, the solid-state imaging device 1201 shown in Figure 12 (A) has a configuration similar to the solid-state imaging device 1 shown in Figure 1. The first electromagnetic wave conversion element 8 and/or the second electromagnetic wave conversion element 10 may be surrounded by the first DTI 12 in a plan view. The charge transfer gate 20 may be disposed on the second surface 6 of the substrate 2 to overlap the first electromagnetic wave conversion element 8 in a plan view. Charges caused by optoelectronic conversion in the first electromagnetic wave conversion element 8 and/or the second electromagnetic wave conversion element 10 may be transferred to the floating diffusion region 18 by turning the charge transfer gate 20 on.
For example, the solid-state imaging device 1202 shown in Figure 12 (B) may comprise a third electromagnetic wave conversion element 1212 between the first DTI  12 and the second DTI 36. The third electromagnetic wave conversion element 1212 may be separated from the first electromagnetic wave conversion element 8. The charge transfer gate 20 may be disposed on the second surface 6 of the substrate 2 to overlap the first electromagnetic wave conversion element 8 in a plan view. At least one charge transfer gate 1222 other than the charge transfer gate 20 may be disposed on the second surface 6 of the substrate 2 to overlap the third electromagnetic wave conversion element 1212 in a plan view. The example shown in Figure 12 (B) provides two charge transfer gates 1222. Charges caused by optoelectronic conversion in the first electromagnetic wave conversion element 8 and/or the second electromagnetic wave conversion element 10 may be transferred to the floating diffusion region 18 by turning the charge transfer gate 20 on. On the other hand, charges caused by optoelectronic conversion in the third electromagnetic wave conversion element 1212 are transferred to the floating diffusion region 18 by turning the charge transfer gate 1222 on.
For example, the solid-state imaging device 1203 shown in Figure 12 (C) may comprise a third electromagnetic wave conversion element 1213 between the first DTI 2 and the second DTI 36. The third electromagnetic wave conversion element 1213 may be coupled to the first electromagnetic wave conversion element 8. The charge transfer gate 20 may be disposed on the second surface 6 of the substrate 2 to overlap the first electromagnetic wave conversion element 8 or the third electromagnetic wave conversion element 1213 in a plan view. The first electromagnetic wave conversion element 8 and the third electromagnetic wave conversion element 1213 share the charge transfer gate 20. Therefore, charges caused by optoelectronic conversion in the first electromagnetic wave conversion element 8 and/or the second electromagnetic wave conversion element 10 and/or the third electromagnetic wave conversion element 1213 are transferred to the floating diffusion region 18 by turning the charge transfer gate 20 on.
For example, the solid-state imaging device 1204 shown in Figure 12 (D) may comprise a third electromagnetic wave conversion element 1214 between the first DTI 12 and the second DTI 36. The third electromagnetic wave conversion element 1214 may be separated from the first electromagnetic wave conversion element 8. The second DTI 36 may be disposed outward of the micro-lens 14 in a plan view, and at least a part of the third electromagnetic wave conversion element 1214 may be  disposed outward of the micro lens 14 in a plan view. The charge transfer gate 20 is disposed on the second surface 6 of the substrate 2 to overlap the first electromagnetic wave conversion element 8 in a plan view. At least one charge transfer gate 1224 other than the charge transfer gate 20 may be disposed on the second surface 6 of the substrate 2 to overlap the third electromagnetic wave conversion element 1214 in a plan view. Charges caused by optoelectronic conversion in the first electromagnetic wave conversion element 8 and/or the second electromagnetic wave conversion element 10 are transferred to the floating diffusion region 18 by turning the charge transfer gate 20 on. Charges by optoelectronic conversion in the third electromagnetic wave conversion element 1214 are transferred to the floating diffusion region 18 by turning the charge transfer gate 1224 on.
For example, the solid-state imaging device 1205 shown in Figure 12 (E) may comprise a third electromagnetic wave conversion element 1215 between the first DTI 12 and the second DTI 36. The third electromagnetic wave conversion element 1215 may be coupled to the first electromagnetic wave conversion element 8. The second DTI 36 may be disposed outward of the micro lens 14 in a plan view. At least a part of the third electromagnetic wave conversion element 1215 may be disposed outward of the micro lens 14 in a plan view. The charge transfer gate 20 is disposed on the second surface 6 of the substrate 2 to overlap the first electromagnetic wave conversion element 8 or the third electromagnetic wave conversion element 1215 in a plan view. The first electromagnetic wave conversion element 8 and the third electromagnetic wave conversion element 1215 share the charge transfer gate 20. Therefore, charges caused by optoelectronic conversion in the first electromagnetic wave conversion element 8 and/or the second electromagnetic wave conversion element 10 and/or the third electromagnetic wave conversion element 1215 are transferred to the floating diffusion region 18 by turning the charge transfer gate 20 on.
For example, the solid-state imaging device 1206 shown in Figure 12 (F) has a configuration similar to the solid-state imaging device 1 shown in Figure 1. The first electromagnetic wave conversion element 8 and/or the second electromagnetic wave conversion element 10 are surrounded by the first DTI 12 in a plan view. The charge transfer gate 20 is disposed on the second surface 6 of the substrate 2 to overlap the first electromagnetic wave conversion element 8 in a plan view. At least  a part of the charge transfer gate 20 may be extended into the substrate 2. Charges caused by optoelectronic conversion in the first electromagnetic wave conversion element 8 and/or the second electromagnetic wave conversion element 10 are transferred to the floating diffusion region 18 by turning the charge transfer gate 20 on.
Figure 13 shows cross-sectional diagrams of solid-state imaging devices 1301 to 1304 according to some embodiments of the present invention.
For example, the solid-state imaging device 1301 shown in Figure 13 (A) comprises an insulation film 1308 disposed on the second surface 6 of the substrate 2. At least one bias electrode 1311 is disposed in the insulation film 1308. The at least one bias electrode 1311 is separated from the second electromagnetic wave conversion element 10. The bias electrode 1311 is electrically coupled to the second electromagnetic wave conversion element 10 via contact 1321. A bias voltage may be applied to the second electromagnetic wave conversion element 10 via the bias electrode 1311 and the contact 1321. Charges caused by optoelectronic conversion in the second electromagnetic wave conversion element 10 may be transferred to and stored in a charge storage region in the substrate (not shown) by applying the bias voltage. After sufficient charges are stored, the charge transfer gate is turned on to transfer the stored charges to the floating diffusion region, which results in substantially increasing the full-well capacity and improving the dynamic range. Furthermore, the application of the bias voltage to the second electromagnetic wave conversion element 10 also provides reduction of the dark current.
For example, the solid-state imaging device 1302 shown in Figure 13 (B) comprises an insulation film 1308 disposed on the second surface 6 of the substrate 2. At least one bias electrode 1312 is disposed in the insulation film 1308 to overlap the second electromagnetic wave conversion element 10 in a plan view. The at least one bias electrode 1312 is separated from the second electromagnetic wave conversion element 10. The bias electrode 1312 is electrically coupled to the second electromagnetic wave conversion element 10 in an indirect manner. Application of the bias voltage to the bias electrode 1312 may provide the improvement of the dynamic range and the reduction of the dark current.
For example, the solid-state imaging device 1303 shown in Figure 13 (C) further comprises a fixed charge film 1313 at least partially covering the second  electromagnetic wave conversion element 10. The fixed charge film 1313 may comprise a material selected from the group including, for example, HfO 2, Al 2O 3, ZrO 2, Ta 2O 5, TiO 2, La 2O 3, Pr 2O 3, CeO 2, Nd 2O 3, Pm 2O 3, Sm 2O 3, Eu 2O 3, Gd 2O 3, Tb 2O 3, Dy 2O 3, Ho 2O 3, Er 2O 3, Tm 2O 3, Yb 2O 3, Lu 2O 3, Y 2O 3, or any combinations thereof. The fixed charge film 1313 may apply a bias voltage to the second electromagnetic wave conversion element 10 by keeping charges in the film.
For example, the solid-state imaging device 1304 shown in Figure 13 (D) further comprises an intrinsic stress film 1314 at least partially covering the second electromagnetic wave conversion element 10. The intrinsic stress film 1314 may be, for example, a tensile stressed silicon nitride liner or a compressively stressed silicon nitride liner. The intrinsic stress film 1314 may apply a stress to the second electromagnetic wave conversion element 10 and may modulate a bandgap of the second electromagnetic wave conversion element 10. In another embodiments, the bandwidth can be tuned to longer wavelengths by admixture of a different band gap material such as Sn in the epitaxy (not shown in the figures) .
Figure 14 shows planar diagrams of solid-state imaging devices 1401 to 1404 according to some embodiments of the present invention. The second electromagnetic wave conversion elements 10 of the solid-state imaging devices 1401 to 1404 shown in Figure 14 may have various planar shapes. Such a second electromagnetic wave conversion element 10 having various planar shapes may increase a spatial efficiency, which results in all of or some of the improvements of charge transfer capability, dark current performance, and quantum efficiency. Such various planar shapes may be selected by choosing, for example, a shape of a mask and an initial shape of a seed layer and a growth condition of an epitaxial growth of the second electromagnetic wave conversion element 10.
For Example, the second electromagnetic wave conversion element 10 of the solid-state imaging device 1401 shown in Figure 14 (A) has a circular shape in a plan view.
For Example, the second electromagnetic wave conversion element 10 of the solid-state imaging device 1402 shown in Figure 14 (B) has an elliptical shape in a plan view.
For Example, the second electromagnetic wave conversion element 10 of the solid-state imaging device 1403 shown in Figure 14 (C) has a rectangular shape in a  plan view.
For Example, the second electromagnetic wave conversion element 10 of the solid-state imaging device 1404 shown in Figure 14 (D) has a polygonal shape in a plan view.
Figure 15 shows expanded cross-sectional diagrams of a first electromagnetic wave conversion element 8 and a second electromagnetic wave conversion element 10 of solid-state imaging devices according to some embodiments of the present invention. As described above, a buffer layer 11 may be disposed between the first electromagnetic wave conversion element 8 and the second electromagnetic wave conversion element 10. The buffer layer 11 may be configured such that, closer to the first electromagnetic wave conversion element 8, the concentration of the first material is higher, and such that, closer to the second electromagnetic wave conversion element 10, the concentration of the second material is higher. The concentration ratio between the first material and the second material may be configured to continuously vary in the buffer layer 11. Alternatively, as shown in the diagrams in Figure 15, the concentration ratio between the first material and the second material may be configured to vary in the buffer layer 11 in a stepped manner. Alternatively, the concentration ratio between the first material and the second material may comprise only the first material, only the second material, or the first material and the second material at a constant concentration ratio across the entire buffer layer 11. In such an embodiment, a concentration of doping may be configured to continuously vary from the first electromagnetic wave conversion element 8 to the second electromagnetic wave conversion element 10. Alternatively, as shown in the diagrams in Figure 15, the doping concentration may be configured to vary in a sub-buffer layer 11-1 and a sub-buffer layer 11-2 in a stepped manner to ensure that generated photocharges in the second electromagnetic wave conversion element 10 can be transferred to the floating diffusion when the transfer gate turns on.
For example, Figure 15 (A) shows a recess 1511 disposed on the second surface 6 of the substrate 2. The buffer layer 11 and the second electromagnetic wave conversion element 10 may be at least partially embedded in the recess 1511. By forming the recess 1511 by isotropic or anisotropic etching, the recess 1511 and the embedded second electromagnetic wave conversion element 10 may have a shape of a half-circular or a polygonal cross section.
For example, Figure 15 (B) shows the second electromagnetic wave conversion element 10 deposited on the second surface 6 on the substrate 2. The buffer layer 11 may be disposed in the substrate 2 by known technique such as atomic diffusion or doping. By selecting the deposition method and/or the etching process after the deposition, the second electromagnetic wave conversion element 10 may have a half-circular or a polygonal cross section.
For example, Figure 15 (C) shows a fin portion 1513 on the second surface 6 of the substrate 2. The fin portion 1513 may protrude from the second surface 6 and may have the same material as the substrate 2. The fin portion 1513 may be formed by deposition. The fin portion 1513 may be formed by etching the surface of the substrate 2 with remaining the area to be the fin portion 1513. Isotropic or anisotropic deposition, or isotropic or anisotropic etching may provide the fin portion 1513 having various cross-sectional shape. The fin portion 1513 may be a part of the first electromagnetic wave conversion element 8 by doping the fin portion 1513. The second electromagnetic wave conversion element 10 may be formed to at least partially cover the fin portion 1513. By selecting a shape of the fin portion 1513, a deposition method, and an etching process after the deposition, the second electromagnetic wave conversion element 10 may have various cross-sectional shape.
For example, Figure 15 (D) shows a recess 1514 on the second surface 6 of the substrate 2. The buffer layer 11 and the second electromagnetic wave conversion element 10 may be at least partially embedded in the recess 1514. Furthermore, an STI 1524 may be disposed adjacent to the buffer layer 11 and the second electromagnetic wave conversion element 10 to at least partially surround the buffer layer 11 and the second electromagnetic wave conversion element 10. The STI 1524 may have various cross-sectional shapes by isotropic or anisotropic etching. The STI 1524 may be filled with, for example, an insulation material. In some embodiments, a silicon capping layer may be formed on top of the second electromagnetic wave conversion element 10 (not shown in the figures) .
Figure 16 shows cross-sectional diagrams of solid-state imaging devices 1601 to 1602 included in a solid-state imaging device array according to some embodiments of the present invention. The solid-state imaging device array comprises a plurality of solid-state imaging devices according to the present invention arranged in an array. Since the solid-state imaging device 1601 is arranged near the center of the solid-state  imaging device array, light approximately vertically impinges the first surface 4 of the substrate 2. Therefore, as shown in Figure 16, the first electromagnetic wave conversion element 8, the second electromagnetic wave conversion element 10, and the micro lens 14 are aligned along the center axis of the solid-state imaging device 1601 in order to receive the light with the highest efficiency. On the other hand, since the solid-state imaging device 1602 is located near the periphery of the solid-state imaging device array, light may impinge the first surface 4 of the substrate 2 from the center of the solid-state imaging device array at a certain angle which has a function of a chief ray angle. Therefore, as shown in Figure 16, the first electromagnetic wave conversion element 8, the second electromagnetic wave conversion element 10, and the micro lens 14 may be shifted toward the direction of the center of the solid-state imaging device array in order to receive the light with the highest efficiency.
Figure 17 shows cross-sectional diagrams showing steps of a method for fabricating a solid-state imaging device 1701 according to some embodiment of the present invention.
In Figure 17 (A) , a substrate 2 comprising a first material having a first bandgap is prepared. The substrate 2 comprises a first surface 4 and a second surface 6 opposite to the first surface 4. The first surface 4 is a surface which electromagnetic wave, for example, light impinges. A first electromagnetic wave conversion element 8 is formed in the substrate 2 by doping. Optionally, STIs 1711 may be formed at a position on the second surface 6 of the substrate 2 where a first DTI 12 is to be formed. The STIs 1711 are to be the tapered portions 1011 explained regarding Figure 10 (A) .
In Figure 17 (B) , a floating diffusion region 18 and readout transistors 30 including a charge transfer gate 20, a source follower device 22, a row select device 24, a reset device 26, and a dual conversion gain device 28 for reading out charge signals from the first electromagnetic wave conversion element 8 and the second electromagnetic wave conversion element 10 are formed on the second surface 6 of the substrate 2 by known semiconductor process.
Then, in Figure 17 (C) , a second electromagnetic wave conversion element 10 comprising a second material having a second bandgap different from the first bandgap is formed on the second surface 6 of the substrate 2. The process stage may  be placed in well-loop, LDD-loop, source-drain-loop, or BEOL-loop. The second electromagnetic wave conversion element 10 may be formed by epitaxial growth. Optionally, the step of forming the second electromagnetic wave conversion element 10 may comprise a sub-step of forming a buffer layer 11 comprising the first material and/or the second material, and a sub-step of forming the second electromagnetic wave conversion element 10 comprising the second material on the buffer layer 11. As described with reference to Figure 15, the buffer layer 11 and the second electromagnetic wave conversion element 10 may be at least partially embedded in a recess disposed on the second surface 6 of the substrate 2. The buffer layer 11 and the second electromagnetic wave conversion element 10 may be disposed to at least partially cover a fin portion disposed on the second surface 6 of the substrate 2. The buffer layer 11 may be configured such that, closer to the second electromagnetic wave conversion element 10, the concentration of the second material is higher in a continuous manner or a stepped manner. Such a configuration may be obtained by varying a supply ratio between the first material and the second material from the deposition sources in a continuous manner or a stepped manner during depositing the buffer layer 11. Alternatively, the buffer layer 11 may have a constant concentration ratio between the first material and the second material, but may be configured such that, closer to the second electromagnetic wave conversion element 10, the doping concentration is higher. The first material may be silicon, and the second material may be SiGe, germanium, InGaAs, GaAs, a III-V material, quantum dots, an organic material, an inorganic material, or other radiation sensitive materials, or any combinations thereof. Preferably, the first material may be silicon, and the second material may be germanium. The first electromagnetic wave conversion element 8 and the second electromagnetic wave conversion element 10 may be appropriately doped to have photosensitivity for visible light and SWIR light, respectively.
Then, in Figure 17 (D) , an insulation film 1712 such as an interlayer insulation film, and metal layers 1713 such as wirings may be formed on the second surface 6 of the substrate 2. The metal layer 1713 may be, for example, wirings for the readout transistors 30. The metal layer 1713 may be, for example, a reflection layer for improving the optoelectronic conversion efficiency of the second electromagnetic wave conversion element 10 as described with reference to Figures 10 and 11. Alternatively, the metal layer 1713 may be a bias electrode for applying a bias voltage  to the second electromagnetic wave conversion element 10 as described with reference to Figure 13.
Then, in Figure 17 (E) , the first surface 4 of the substrate 2 may optionally be polished or grinded for thinning the substrate 2. After thinning down, a support wafer 1715 or a wafer 1715 comprising an integrated circuit may be bonded on the side of the second surface 6 of the substrate 2.
Then, in Figure 17 (F) , a recess 1714 may optionally be disposed on the first surface 4 of the substrate 2 to overlap the second electromagnetic wave conversion element 10 in a plan view. The recess 1714 may be a light condensing element for condensing SWIR light to the second electromagnetic wave conversion element 10.
Then, in Figure 17 (G) , a first DTI 12 and a second DTI 36 may be formed from the first surface 4 of the substrate 2 toward the second surface 6. The first DTI 12 may at least partially surround the first electromagnetic wave conversion element 8 and the second electromagnetic wave conversion element 10 in a plan view. The first DTI 12 may be connected to the STIs 1711 to form the tapered portion 1011. The tapered portion 1011 may be a light condensing element for condensing SWIR light to the second electromagnetic wave conversion element 10.
Then, in Figure 17 (H) , a grid structure 16, an insulation film 1715, and a micro lens 14 may be disposed on the first surface 4 of the substrate 2.
Figure 18 shows a partial cross-sectional diagram of a solid-state imaging device array comprising a plurality of solid-state imaging devices 1 according to some embodiments of the present invention. The second side 6 of the substrate 2 of the solid-state imaging devices 1 may be bonded to an integrated circuit chip 1801 for controlling the solid-state imaging devices 1 and processing signals from the solid-state imaging devices 1.
Figure 19 shows perspective diagrams of image sensors 1901 to 1905 comprising a solid-state imaging device array according to some embodiments of the present invention.
In Figure 19 (A) , the image sensor 1901 may comprise a pixel array 1911, a control circuit 1921, and a logic circuit 1931 integrated on one chip.
In Figure 19 (B) , the image sensor 1902 may comprise a first chip on which a pixel array 1912 and a control circuit 1922 are integrated, and a second chip stacked on the first chip and comprising a logic circuit 1932.
In Figure 19 (C) , the image sensor 1903 may comprise a first chip comprising a pixel array 1913, and a second chip stacked on the first chip and on which a control circuit 1923 and a logic circuit 1933 are integrated.
In Figure 19 (D) , the image sensor 1904 may comprise a first chip comprising a pixel array 1914, a second chip comprising a memory circuit 1944, and a third chip on which a control circuit 1924 and a logic circuit 1934 are integrated. The first, second, and third chips may be stacked.
In Figure 19 (E) , the image sensor 1905 may comprise a first chip comprising a pixel array 1915, a second chip comprising a pixel circuit 1955, and a third chip on which a control circuit 1925 and a logic circuit 1935 are integrated. The first, second, and third chips may be stacked.
Figure 20 shows a block diagram of an image sensor 2000 such as an image sensor shown in Figure 19. The image sensor 2000 may comprise: a lens 2002; a solid-state imaging device array 2009; a shutter 2003 disposed between the lens 2002 and the solid-state imaging device array 2009; a control circuit 2005 for controlling the solid-state imaging device array 2009 and the shutter 2003; a signal processing circuit 2006 for processing output signals from the solid-state imaging device array 2009; a monitor 2007 for displaying an image processed and output by the signal processing circuit 2006; and a memory 2008 for storing an image processed and output by the signal processing circuit 2006.
The solid-state imaging devices described above may be applied to various fields including, for example, sports, beauty care, security, home appliances, agriculture, entertainment, transportation, and medical, treatment, and health care as shown in Figure 21. The solid-state imaging devices described above may be used as external monitor sensors of a vehicle.
Although the embodiments of the present invention were illustratively described, those skilled in the art may easily understand that various modifications and changes are available without deviating from the spirit and the scope of the present invention as shown in Figure 22.
Designations
1, 601 to 607, 701 to 706, 801 to 804, 901 and 902, 1001 to 1005, 1101 to 1105, 1201 to 1206, 1301 to 1304, 1401 to 1405, 1601 and 1602, and 1701: Solid-state imaging  device;
2: Substrate;
4: First surface;
6: Second surface;
8: First electromagnetic wave conversion element;
10: Second electromagnetic wave conversion element;
11: Buffer layer;
11-1 and 11-2: Sub-buffer layer;
12: First DTI;
12-1 and 12-2: DTI;
14: Micro lens;
16: Grid structure;
18: Floating diffusion region;
20: Charge transfer gate;
22: Source follower device;
24: Row select device;
26: Reset device;
28: Dual conversion gain device;
30: Readout transistors;
32: Device power source;
34: Column output line;
36: Second DTI;
201: Imaging system;
204: Bit line;
205: Control circuit;
206: Signal processing circuit;
209: Pixel array;
210: Readout circuit;
911 and 912: Recess;
1011: Tapered portion;
1012: STI;
1013: Aperture;
1014: Micro lens;
1015: Reflective layer;
1108: Insulation film;
1111, 1112, 1121-1, 1121-2, 1114, 1114-1, 1114-2, 1115, 1115-1, 1115-2: Metal layer;
1113: Reflective layer;
1124: Contact;
1125: Via;
1212 to 1215: Third electromagnetic wave conversion element;
1222 and 1224: Charge transfer gate;
1308: Insulation film;
1311 and 1312: Bias electrode;
1313: Fixed charge film;
1314: Intrinsic stress film;
1321: Contact;
1511: Recess;
1513: Fin portion;
1514: Recess;
1524: STI;
1711: STI;
1712: Insulation film;
1713: Metal layer;
1714: Recess;
1715: Insulation film;
1911 to 1915: Pixel array;
1921 to 1925: Control circuit;
1931 to 1935: Logic circuit;
1944: Memory circuit;
1955: Pixel circuit;
2000: Image sensor;
2002: Lens;
2003: Shutter
2005: Control circuit;
2006: Signal processing circuit;
2007: Monitor;
2008: Memory; and
2009: Solid-state imaging device array

Claims (40)

  1. An image apparatus, comprising:
    a substrate having a first surface, on which an electromagnetic wave impinges, and a second surface opposite to the first surface;
    a first electromagnetic wave conversion element formed in the substrate and composed of a first material having a first bandgap;
    a second electromagnetic wave conversion element on a side of the second surface and composed of a second material having a second bandgap different from the first bandgap such that the second electromagnetic wave conversion element overlaps the first electromagnetic wave conversion element in a plan view; and
    a first deep trench isolation (DTI) extending in the substrate from the first surface toward the second surface and at least partially surrounding the first electromagnetic wave conversion element and the second electromagnetic wave conversion element in a plan view.
  2. The image apparatus according to Claim 1, further comprising a buffer layer disposed between the first electromagnetic wave conversion element and the second electromagnetic wave conversion element, wherein the buffer layer comprises the first material and the second material.
  3. The image apparatus according to Claim 2, wherein the buffer layer is configured such that, closer to the second electromagnetic wave conversion element, a concentration of the second material is higher.
  4. The image apparatus according to Claim 2, further comprising a buffer layer disposed between the first electromagnetic wave conversion element and the second electromagnetic wave conversion element and including the second material,
    wherein, closer to the second electromagnetic wave conversion element, a doping concentration of the buffer layer is configured to be higher.
  5. The image apparatus according to Claim 1,
    wherein the first material is silicon, and
    wherein the second material is selected from the group consisting of SiGe, germanium, InGaAs, GaAs, a III-V material, quantum dots, an organic material, an inorganic material, or other radiation sensitive material, or combinations thereof.
  6. The image apparatus according to Claim 1, wherein the first DTI is configured to reflect electromagnetic wave impinging the image apparatus to condense the electromagnetic wave to the second electromagnetic wave conversion element.
  7. The image apparatus according to Claim 1, wherein the first DTI is disposed on a periphery or inward of the periphery of the image apparatus in a plan view.
  8. The image apparatus according to Claim 7, further comprising a second DTI extending in the substrate from the first surface toward the second surface and at least partially surrounding the first DTI.
  9. The image apparatus according to Claim 7 or 8, wherein a depth of the first DTI is less than or equal to a thickness of the substrate.
  10. The image apparatus according to Claims 8 or 9, wherein a depth of the second DTI is less than or equal to a thickness of the substrate.
  11. The image apparatus according to Claim 1,
    wherein the first electromagnetic wave conversion element has a polygonal shape in a plan view, and
    wherein the first DTI is disposed on at least a part of at least two sides of the first electromagnetic wave conversion element in a plan view.
  12. The image apparatus according to any one of Claims 1 to 11, further comprising a light-condensing element configured to condense electromagnetic wave impinging the first surface to the second electromagnetic wave conversion element.
  13. The image apparatus according to Claim 12, wherein the light-condensing  element is at least one recess disposed on the first surface.
  14. The image apparatus according to Claim 12, wherein the light-condensing element is a tapered portion of the first DTI disposed on the second surface such that, closer to the second surface, the thickness in a plan view is larger toward the second electromagnetic wave conversion element.
  15. The image apparatus according to Claim 12, wherein the light-condensing element is a shallow trench isolation (STI) disposed inside of the first DTI in a plan view and at least partially surrounding the second electromagnetic wave conversion element.
  16. The image apparatus according to Claim 12, wherein the light-condensing element is a light-shielding layer comprising an aperture overlapping with the first electromagnetic wave conversion element.
  17. The image apparatus according to Claim 12, wherein the light-condensing element is a lens disposed on the first surface.
  18. The image apparatus according to Claim 12, wherein the light-condensing element is a metal layer disposed on the second surface and at least partially surrounding the second electromagnetic wave conversion element.
  19. The image apparatus according to Claim 12,
    wherein an insulation film is disposed on the second surface, and
    wherein the light-condensing element is a metal layer in the insulation film such that the metal layer overlaps the second electromagnetic wave conversion element in a plan view.
  20. The image apparatus according to Claim 19, wherein the light-condensing element further comprises a metal layer in the insulation film such that the metal layer at least partially surrounds the second electromagnetic wave conversion element in a plan view.
  21. The image apparatus according to Claim 20,
    wherein the metal layer at least partially surrounding the second electromagnetic wave conversion element electrically couples to the first electromagnetic wave conversion element by contacts, and
    wherein the contacts at least partially surround the second electromagnetic wave conversion element.
  22. The image apparatus according to Claim 20,
    wherein the metal layer overlapping the second electromagnetic wave conversion element electrically couples to the metal layer at least partially surrounding the second electromagnetic wave conversion element by vias, and
    wherein the vias at least partially surround the second electromagnetic wave conversion element.
  23. The image apparatus according to Claim 12, wherein the light-condensing element is a silicidation layer disposed on outer surfaces of the second electromagnetic wave conversion layer.
  24. The image apparatus according to Claim 8, further comprising at least one third electromagnetic wave conversion element disposed in the substrate and at least partially between the first DTI and the second DTI, the third electromagnetic wave conversion element being composed of the first material having the first band gap.
  25. The image apparatus according to Claim 24, wherein the first electromagnetic wave conversion element and the third electromagnetic wave conversion element are coupled to different charge transfer gates disposed on the second surface, respectively.
  26. The image apparatus according to Claim 1,
    wherein the first electromagnetic wave conversion element is coupled to a charge transfer gate disposed on the second surface, and
    wherein the charge transfer gate extends into the substrate.
  27. The image apparatus according to Claim 1, further comprising a bias electrode electrically coupled to the second electromagnetic wave conversion element and configured to apply a bias voltage to the second electromagnetic wave conversion element.
  28. The image apparatus according to Claim 1, further comprising:
    an insulation film disposed on the second surface; and
    a bias electrode in the insulation film, the bias electrode overlapping the second electromagnetic wave conversion element in a plan view, and separated from the second electromagnetic wave conversion element.
  29. The image apparatus according to Claim 1, further comprising a fixed charge film or an intrinsic stress film at least partially covering the second surface and the second electromagnetic wave conversion element.
  30. The image apparatus according to Claim 1, wherein the second electromagnetic wave conversion element is at least partially embedded in the first electromagnetic wave conversion element on the second surface.
  31. The image apparatus according to Claim 1,
    wherein the first electromagnetic wave conversion element comprises a fin portion protruded from the second surface, and
    wherein the second electromagnetic wave conversion element at least partially covers the fin portion.
  32. The image apparatus according to Claim 15,
    wherein the STI is disposed to be in contact with the second electromagnetic wave conversion element, and
    wherein the STI is filled with an insulation material.
  33. An image apparatus array comprising the image apparatuses according to any one of Claims 1 to 32,
    wherein the image apparatuses are arranged in an array, and
    wherein the second electromagnetic wave conversion element of at least one image apparatus is shifted from a center of the image apparatus toward a center of the image apparatus array in a plan view.
  34. A method of manufacturing an image apparatus, comprising at least:
    preparing a substrate having a first surface which electromagnetic wave impinges and a second surface opposite to the first surface, the substrate comprising a first material having a first band gap;
    forming a first electromagnetic wave conversion element in the substrate by doping;
    forming a charge transfer gate coupled to the first electromagnetic wave conversion element on the second surface;
    forming a second electromagnetic wave conversion element on the second surface, the second electromagnetic wave conversion element comprising a second material having a second bandgap different from the first bandgap by epitaxial growing; and
    forming a first deep trench isolation (DTI) in the substrate from the first surface toward the second surface, the first DTI at least partially surrounding the first electromagnetic wave conversion element and the second electromagnetic wave conversion element in a plan view.
  35. The method according to Claim 34, wherein the step of forming the second electromagnetic wave conversion element comprises:
    a sub-step of forming a buffer layer comprising the first material and/or the second material by epitaxial growing; and
    a sub-step of forming the second electromagnetic wave conversion element composed of the second material on the buffer layer by epitaxial growing.
  36. The method according to Claim 35, wherein the buffer layer is configured such that, closer to the second electromagnetic wave conversion element, a concentration of the second material is higher.
  37. The method according to Claim 35, wherein the buffer layer is configured such that, closer to the second electromagnetic wave conversion element, a concentration of doping is higher.
  38. The method according to Claim 34,
    wherein the first material is silicon; and
    wherein the second material is selected from the group consisting of SiGe, germanium, InGaAs, GaAs, a III-V material, quantum dots, an organic material, an inorganic material, or other radiation sensitive material, or combinations thereof.
  39. The method according to Claim 34, further comprising forming a second DTI at least partially surrounding the first DTI.
  40. The method according to Claim 34, further comprising forming a light-condensing element configured to condense electromagnetic wave impinging the first surface to the second electromagnetic wave conversion element.
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