WO2011155009A1 - Solid-state image pickup device and method for manufacturing same - Google Patents

Solid-state image pickup device and method for manufacturing same Download PDF

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Publication number
WO2011155009A1
WO2011155009A1 PCT/JP2010/007374 JP2010007374W WO2011155009A1 WO 2011155009 A1 WO2011155009 A1 WO 2011155009A1 JP 2010007374 W JP2010007374 W JP 2010007374W WO 2011155009 A1 WO2011155009 A1 WO 2011155009A1
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Prior art keywords
solid
recess
imaging device
state imaging
light
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PCT/JP2010/007374
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French (fr)
Japanese (ja)
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田中　浩司
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パナソニック株式会社
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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
    • H01L27/14625—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
    • H01L27/148—Charge coupled imagers
    • H01L27/14806—Structural or functional details thereof
    • H01L27/14812—Special geometry or disposition of pixel-elements, address lines or gate-electrodes
    • H01L27/14818—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
    • H01L27/148—Charge coupled imagers
    • H01L27/14831—Area CCD imagers

Definitions

  • the present invention relates to a solid-state imaging device and a method for manufacturing the same, and particularly to a technique for suppressing deterioration in image quality.
  • solid-state imaging devices have been used for digital still cameras, digital movie cameras, mobile phones, and the like. As these devices become widespread, demands for higher resolution and a larger number of pixels for solid-state imaging devices have increased, and pixel miniaturization has been promoted.
  • Such a solid-state imaging device includes a photoelectric conversion unit provided at the position of each pixel, a semiconductor substrate provided with a transfer channel for transferring charges converted by the photoelectric conversion unit, and an upper surface of the semiconductor substrate and a photoelectric conversion unit. And a light-shielding film having an opening in a region corresponding to the conversion unit.
  • an optical waveguide unit is provided in the opening of the light-shielding film to guide light incident from above to emit downward from the light exit surface and guide it to the photoelectric conversion unit.
  • the light emitting surface of the optical waveguide portion is arranged at a position higher than the upper surface of the semiconductor substrate.
  • the light guided through the optical waveguide portion is diffracted by the light exit surface when it is emitted from the light exit surface.
  • the opening width of the light shielding film is reduced to 1 [ ⁇ m] or less, and accordingly, the width of the light exit surface of the optical waveguide portion is 1 [ ⁇ m] or less. The closer the width of this light exit surface is to the wavelength of light, the greater the diffraction of light that occurs on the light exit surface. For this reason, a part of the diffracted light may circulate toward the transfer channel in the semiconductor substrate and light may be generated near the transfer channel.
  • an object of the present invention is to provide a solid-state imaging device capable of suppressing deterioration in image quality due to diffracted light and a manufacturing method thereof.
  • a solid-state imaging device covers a photoelectric conversion unit, a semiconductor substrate provided with a transfer channel for transferring charges converted by the photoelectric conversion unit, and an upper surface of the semiconductor substrate. And a light shielding film having an opening provided in a region corresponding to the photoelectric conversion unit and a plurality of transparent materials having different refractive indexes provided in the opening, and guides light incident from above to emit light.
  • An optical waveguide portion that emits from a surface, and a region corresponding to the transfer channel on the upper surface of the semiconductor substrate is a reference surface, and a recess that is lower than the reference surface is formed in a region corresponding to the photoelectric conversion portion on the upper surface
  • the light emitting surface of the optical waveguide portion is disposed in the recess of the semiconductor substrate so that the light emitting surface is at a position lower than the reference surface of the semiconductor substrate.
  • the method for manufacturing a solid-state imaging device includes a first step of forming a photoelectric conversion unit and a transfer channel for transferring a charge converted by the photoelectric conversion unit in a semiconductor substrate; A second step of forming a light-shielding film covering an upper surface and having an opening provided in a region corresponding to the photoelectric conversion unit; and the opening of the light-shielding film is made of a plurality of transparent materials having different refractive indexes, A third step of forming an optical waveguide portion that guides light incident from below and emits the light from the light exit surface, wherein the method further includes a step between the first step and the third step.
  • the third step Te place the light exit surface of the optical waveguide portion into the recess of the semiconductor substrate, characterized by the position of the light emitting surface lower than the reference surface of the semiconductor substrate.
  • a region corresponding to the transfer channel on the upper surface of the semiconductor substrate is used as a reference surface, and a recess that is lower than the reference surface is provided in a region corresponding to the photoelectric conversion unit on the upper surface.
  • the light exit surface where light diffraction occurs is located higher than the upper surface (reference surface) of the semiconductor substrate.
  • the position of the light emitting surface where light is diffracted is lower than that of a conventional solid-state imaging device located at a position higher than the upper surface (reference surface) of the semiconductor substrate. Will spread. For this reason, light that travels to the transfer channel side passes through a deeper position in the semiconductor substrate, that is, a position farther from the transfer channel, and the amount of light that enters the vicinity of the transfer channel becomes smaller than in the past.
  • the charge generated by light in the vicinity of the transfer channel is reduced, so that noise charges mixed with the signal charge in the transfer channel can be reduced, and deterioration of image quality can be suppressed.
  • FIG. 1 is a schematic block diagram showing a schematic configuration of a solid-state imaging device 10 according to Embodiment 1 of the present invention. It is a schematic cross section which shows the structure of the imaging pixel part 10a of the solid-state imaging device 10 concerning Embodiment 1 of this invention.
  • (A) is a figure which shows an example of the diffracted light in the solid-state imaging device which concerns on the prior art as a reference
  • (b) is a figure which shows an example of the diffracted light in the solid-state imaging device 10.
  • 3 is a schematic cross-sectional view showing some steps in manufacturing the solid-state imaging device 10.
  • FIG. 3 is a schematic cross-sectional view showing some steps in manufacturing the solid-state imaging device 10.
  • the solid-state imaging device 10 includes a plurality of imaging pixel units 10a arranged in a matrix, a vertical CCD unit 10b extending in the Y-axis direction, and an X-axis.
  • a horizontal CCD unit 10c extending in the direction and an amplifier unit 10d following the horizontal CCD unit 10c are formed.
  • the configuration of an interline (IT) -CCD type solid-state imaging device is employed.
  • a charge corresponding to the amount of incident light is generated by photoelectric conversion.
  • the vertical CCD unit 10b is formed adjacent to the imaging pixel unit 10a of each column, and has a function of receiving a signal charge generated by the imaging pixel unit 10a and transferring it downward in the Y-axis direction.
  • the signal charges in the vertical CCD unit 10b are sequentially transferred to the horizontal CCD unit 10c in parallel and output through the amplifier unit 10d.
  • Imaging Pixel Unit 10a The configuration of the imaging pixel unit 10a and its peripheral part will be described with reference to FIG.
  • the solid-state imaging device 10 has a silicon substrate 1 as a semiconductor substrate.
  • the silicon substrate 1 includes an n-type region 1a and a p-type well region 1b provided on the n-type region 1a.
  • a photodiode 2 is formed in the p-type well region 1b.
  • a vertical transfer channel 3a for transferring signal charges from the photodiode 2 is formed on one side of the photodiode 2 in the p-type well region 1b, and another adjacent photo diode is formed on the other side of the photodiode 2.
  • a vertical transfer channel 3b for transferring signal charges from the diode is formed.
  • a p + layer 12 is formed along the upper surface 1c of the silicon substrate 1 on the photodiode 2 in the p-type well region 1b.
  • the first insulating film 14a includes a thin film portion 14a1 in a region on the p + layer 12 of the silicon substrate 1, that is, a region corresponding to the photodiode 2, and a thick film portion 14a2 in a region corresponding to the vertical transfer channels 3a and 3b. Become.
  • a vertical transfer electrode 4 made of polycrystalline silicon is formed on the thick film portion 14a2 of the first insulating film 14a.
  • An antireflection film 13 made of silicon nitride is formed on the thin film portion 14a1 of the first insulating film 14a.
  • a second insulating film 14b made of silicon oxide is formed on the vertical transfer electrode 4 and the antireflection film 13 formed on the first insulating film 14a.
  • a light shielding film 5 made of a metal material such as aluminum covering the upper surface of the silicon substrate 1 is formed.
  • the light shielding film 5 is provided with an opening 5 a in a region corresponding to the photodiode 2.
  • the light shielding film 5 extends downward from the opening edge of the plate-like portion 5 b so as to follow the plate-like portion 5 b formed along the upper surface of the vertical transfer electrode 4 and the side surface of the vertical transfer electrode 4. It consists of the cylindrical part 5c.
  • a low refractive index layer 6 made of a transparent material having a first refractive index, for example, silicon oxide (refractive index 1.45) is formed on the light shielding film 5 formed on the second insulating film 14b.
  • the thickness of the low refractive index layer 6 is about 100 [nm].
  • the low refractive index layer 6 is formed along the surface of the light shielding film 5 in the region where the light shielding film 5 exists, and in the region where the light shielding film 5 does not exist, that is, in the region corresponding to the photodiode 2, the second insulating film 14 b. It is formed along the surface.
  • a high refractive index layer 7 made of a transparent material having a second refractive index higher than the first refractive index, for example, silicon nitride (refractive index 2.0) is formed.
  • the high refractive index layer 7 is formed with a thickness sufficient to fill the inside of the opening 5a of the light shielding film 5 and flatten the upper surface.
  • a color filter layer 8 in which a pigment is dispersed in an organic material is formed.
  • a flattening layer 9 for flattening the upper surface is formed on the color filter layer 8.
  • a microlens 11 for condensing incident light on the photodiode 2 is formed.
  • the low refractive index layer 6 and the high refractive index layer 7 are formed in the opening 5a of the light shielding film 5. Since the low refractive index layer 6 is formed along the surface of the light shielding film 5, a cylindrical shape along the inner peripheral surface of the cylindrical portion 5 c of the light shielding film 5 is formed inside the opening 5 a of the light shielding film 5. A clad portion 6a is formed. In the high refractive index layer 7, a core portion 7 a is formed inside the opening 5 a of the light shielding film 5 and is embedded in the cylinder of the cladding portion 6 a of the low refractive index layer 6. The clad portion 6a and the core portion 7a constitute an optical waveguide portion 20 that guides incident light downward from above.
  • vertical transfer channels 3a and 3b may be collectively referred to as “vertical transfer channel 3”.
  • the lower end surface of the core portion 7a is a light emitting surface 20a, and the optical waveguide portion 20 can emit light incident from above from the light emitting surface 20a and guide it to the photodiode 2.
  • the light exit surface 20b is shown by a thick line for easy understanding.
  • the optical waveguide part 20 light can be totally reflected at the interface between the core part 7a and the clad part 6a having different refractive indexes, and thereby the light collection efficiency to the photodiode 2 can be increased.
  • a region corresponding to the photodiode 2 on the upper surface 1 c of the silicon substrate 1 is used as a reference surface S, and a region corresponding to the vertical transfer channel 3 (see FIG. 2A) on the upper surface 1 c is used as a reference surface S.
  • a recess 21 that forms a step lower than the surface S is provided.
  • the optical waveguide portion 20 is provided from the inside of the opening 5 a of the light shielding film 5 to the concave portion 21 of the silicon substrate 1, and the light emitting surface 20 a of the optical waveguide portion 20 is disposed in the concave portion 21 of the silicon substrate 1. Has been. In this way, the position of the light emitting surface 20a of the optical waveguide portion 20 (Py shown in FIG. 2B) is set lower than the position of the reference surface S of the silicon substrate 1 (Px shown in FIG. 2B). is doing.
  • the depth d1 of the recess 21 is about 220 [nm]
  • the depth d2 of the light emitting surface 20a from the reference plane S is about 100 [nm].
  • the thickness of the thin film portion 14a1 in the first insulating film 14a is about 20 [nm]
  • the thickness of the antireflection film 13 is about 50 [nm]
  • the thickness of the second insulating film 14b is about 50 [nm]. is there.
  • the solid-state imaging device 10 having the above configuration, when incident light from the microlens 11 passes through the optical waveguide portion 20, light is diffracted on the light emission surface 20a of the optical waveguide portion 20, but the light emission surface 20a. Is made lower than the reference plane S of the silicon substrate 1, it is possible to suppress deterioration in image quality due to diffracted light as compared with the conventional solid-state imaging device.
  • FIG. 3A is a diagram illustrating an example of light diffracted by the light exit surface of the optical waveguide portion in the conventional solid-state imaging device
  • FIG. 3B is an optical waveguide in the solid-state imaging device 10 of the present embodiment. It is a figure which shows an example of the light diffracted by the light-projection surface of a part.
  • the position P9 of the light emitting surface 99a of the optical waveguide part 99 made of is higher than the position Px of the upper surface 91a (reference surface) of the silicon substrate 91. For this reason, like the incident light L9, the light diffracted by the light exit surface 99a of the optical waveguide portion 99 has already spread when passing through the upper surface 91a (reference surface) of the silicon substrate 91.
  • the light emission surface 20a of the optical waveguide portion 20 is disposed in the concave portion 21 of the silicon substrate 1, so that the light Since the position Py of the emission surface 20a is lower than the position Px of the reference surface S of the silicon substrate 1, there is no spread due to diffraction when passing through the position Px of the reference surface S of the silicon substrate 1 as in the incident light L1.
  • the light exits from the light exit surface 20a lower than the reference surface S it spreads by diffraction.
  • the diffracted light spreads at a deeper position in the silicon substrate 1 than in the prior art, even if it wraps around the vertical transfer channel 3a side, it is more deep from the silicon substrate 1, that is, from the vertical transfer channel 3a.
  • the amount of light incident on the vicinity of the vertical transfer channel 3a can be reduced by passing through a distant position.
  • FIG. 3B shows a boundary on which of the photodiode 2, the vertical transfer channel 3 and the N-type region 1a the charge generated by light moves in the silicon substrate 1 depending on the position where the charge is generated.
  • the lines B1, B2 and B3 showing are drawn with a two-point difference line.
  • the boundary lines B1, B2, and B3 are determined by the potential distribution in the silicon substrate 1.
  • the P-type well region 1b functions as a potential barrier between the photodiode 2, the vertical transfer channel 3, and the N-type region 1a, and the lines connecting the highest potential barriers are the boundary lines B1, B2. , B3.
  • the incident light L1 is incident on the region. It is converted into electric charge e.
  • the charges e thus generated move to the photodiode 2 due to the potential gradient, and are collected by the photodiode 2 to become signal charges.
  • some of the light emitted from the light exit surface 20a of the optical waveguide portion 20 enters the region below the boundary line B3 beyond the boundary line B3, and is converted into electric charge in the region. Is done.
  • the charges generated here move to the N-type region 1a due to the potential gradient and are discharged from the N-type region 1a.
  • the remaining light is incident on a region inside the boundary line B1 (on the vertical transfer channel 3a side) or a region inside the boundary line B2 (on the vertical transfer channel 3b side), and is converted into electric charge in the incident region.
  • the charges generated inside the boundary line B1 move to the vertical transfer channel 3a due to the potential gradient. For this reason, noise charges mixed in signal charges from other photodiodes transferred in the vertical transfer channel 3a are generated, leading to degradation of image quality.
  • the charge generated inside the boundary line B2 moves to the vertical transfer channel 3b due to the potential gradient, and similarly, noise mixed into signal charges from other photodiodes transferred in the vertical transfer channel 3b. It becomes electric charge and leads to deterioration of image quality.
  • the inventors In order to reduce the amount of light incident on the regions inside the boundary lines B1 and B2 by the diffracted light, the inventors have made the diffracted light spread at a deeper position in the silicon substrate 1, thereby making the vertical It has been considered to allow the light that travels to the transfer channels 3a and 3b to pass below the boundary lines B1 and B2.
  • the position of the light emitting surface where the light is diffracted may be lowered.
  • the light emitting surface is simply Even if the position is to be lowered, there is a limit to the position of the upper surface 91a (reference surface) of the silicon substrate 91 (see FIG. 3A).
  • the present inventors provide a concave portion 21 on the upper surface 1c of the silicon substrate 1, and dispose the light emitting surface 20a of the optical waveguide portion 20 in the concave portion 21, whereby the position of the light emitting surface 20a where light diffraction occurs. Py is set lower than the position Px of the reference surface S so that the diffracted light spreads at a deeper position in the silicon substrate 1.
  • the amount of light that passes through the lower side of the boundary lines B1 and B2 out of the light that circulates toward the vertical transfer channel 3 side becomes larger than that of the conventional solid-state imaging device 90, and therefore, the inner side of the boundaries B1 and B2 The amount of light incident on each region is reduced. As a result, the noise charge can be reduced.
  • the position of the light exit surface where light diffraction occurs and the reduction of noise charge are related.
  • the noise charge reducing effect in this embodiment is about 5 dB.
  • the core portion 7a of the optical waveguide portion 20 is made of silicon nitride having a refractive index of 2.0, the wavelength of light passing through the core portion 7a is halved compared to the air. Accordingly, the influence of diffraction can be suppressed.
  • 4 and 5 are schematic cross-sectional views for explaining a method for manufacturing the solid-state imaging device 10. 4 and 5 show the end face of the intermediate product in each step.
  • an n-type region 1a, a p-type well region 1b, a photodiode 2 and a vertical transfer channel 3 are formed in a silicon substrate 1, and then an oxide film is formed on the entire silicon substrate 1.
  • the silicon oxide film 30 is formed by thermally oxidizing the surface of the stacked oxide film (FIG. 4A).
  • the bottom portion of the formed recess 32 is thermally oxidized, and the entire formation region of the recess 21 is filled with a thermal oxide film 33 (FIG. 4C).
  • the thermal oxidation here is performed until the depth of the recess 21 (220 [nm] in this example) is reached, and therefore, thermal oxidation is required from the bottom of the recess 32 to a depth of 120 [nm].
  • the recess 32 having a depth d2 shallower than the depth d1 of the recess 21 is formed, and the bottom portion of the formed recess 32 is thermally oxidized, thereby thermally oxidizing with a resist pattern having an opening on a flat surface.
  • a resist pattern having an opening on a flat surface can suppress the occurrence of bird's beak.
  • the opening end of the resist pattern is in direct contact with the silicon substrate, so that a bird's beak-shaped oxide film is formed by lateral thermal oxidation.
  • the end portion of the opening portion of the resist pattern 31 does not directly contact the silicon substrate 1 and is further flat. Because it is not, it does not have a shape like a bird's beak. Further, the resist pattern 31 can be deposited to a thickness of about 200 nm to suppress bird's beaks. Further, after forming the recess 32, an oxide film wet etching process is performed to recede the oxide film under the resist pattern 31 by about 20 nm. It is also possible to reduce the bird's beak by performing thermal oxidation afterwards.
  • the thermal oxide film 33 is removed with hydrofluoric acid, and then the resist pattern 31 is removed with phosphoric acid boil (FIG. 4D). As a result, a recess 21 having a depth d1 (220 [nm]) is completed.
  • Step of forming first insulating film and p + layer A first insulating film comprising a thin film portion 14a1 and a thick film portion 14a2 by depositing a silicon oxide film on the recess 21 and the silicon oxide film 30 by a CVD method. 14a is formed, and boron (B) is ion-implanted using a resist pattern corresponding to the formation region of the p + layer 12 in the silicon substrate 1 to form the p + layer 12 (FIG. 4E). )).
  • a vertical transfer electrode 4 made of a polycrystalline silicon film is formed in a region corresponding to the vertical transfer channel 3 on the first insulating film 14a by using a CVD method and a photolithography method (FIG. 4). (E)).
  • a silicon oxide film is deposited on the vertical transfer electrode 4 and the antireflection film 13 formed on the first insulating film 14a by a CVD method to form a second insulating film 14b (FIG. 5A).
  • silicon nitride is deposited on the low refractive index layer 6 by the CVD method, and silicon nitride is deposited until the cylinder of the cladding portion 6a of the low refractive index layer 6 is completely filled.
  • the high refractive index layer 7 is formed by planarizing the upper surface of the deposited silicon nitride by the CMP method (FIG. 5C).
  • a core portion 7 a is formed in the opening 5 a of the light shielding film 5 and embedded in the cylinder of the cladding portion 6 a of the low refractive index layer 6.
  • the optical waveguide portion 20 composed of the cladding portion 6a and the core portion 7a is completed.
  • the optical waveguide portion 20 extending from the inside of the opening portion 5a of the light shielding film 5 to the concave portion 21 of the silicon substrate 1 is formed, so that the position Py of the light emitting surface 20a of the optical waveguide portion 20 is the reference of the silicon substrate 1. It becomes lower than the position Px of the surface S.
  • the solid-state imaging device 10 is manufactured through the above steps.
  • silicon crystal defects are generated on the inner peripheral surface of the recess 21, but by forming the P + layer 12 along the inner peripheral surface of the recess 21 in the silicon substrate 1, the recess 21 is formed. Even if charges are generated due to silicon crystal defects on the inner peripheral surface, the generated charges can be prevented from being mixed with the signal charges of the photodiode 2.
  • FIG. 6 is a schematic cross-sectional view showing the main part of the solid-state imaging device 40.
  • the lower end of the cylindrical portion 5c of the light shielding film 5 is located higher than the position Px of the reference plane S of the silicon substrate 1, a part of the optical waveguide portion 20 Is not surrounded by the cylindrical portion 5 c of the light shielding film 5.
  • the cylindrical portion 45c of the light shielding film 45 extends to the inside of the recess 21 of the silicon substrate 1, and the lower end of the cylindrical portion 45c.
  • the position Pz is lower than the position Px of the reference plane S of the silicon substrate 1, and the optical waveguide portion 49 is entirely surrounded by the cylindrical portion 45 c of the light shielding film 45.
  • the same components as those of the solid-state imaging device 10 shown in FIG. 2 are denoted by the same reference numerals for the sake of simplicity, and the description thereof is omitted.
  • the incident angle of light with respect to the interface is constant.
  • An angle ⁇ or more is necessary.
  • the incident angle ⁇ of light is 46.5 [°] for total reflection at the interface. As described above, when the incident angle ⁇ is less than 46.5 [°], light passing through the interface is generated.
  • the light is not surrounded by the cylindrical portion 5c of the light shielding film 5 of the optical waveguide unit 20 such as when light from above enters the optical waveguide unit 20 obliquely.
  • light having an incident angle ⁇ of less than 46.5 [°] is incident on the interface between the core portion 7a and the cladding portion 6a, light passing through the interface is generated and light is transmitted from the outer periphery of the optical waveguide portion.
  • the charge generated by the light becomes a noise charge mixed with the signal charge in the transfer channel, which causes a problem that the image quality deteriorates.
  • the cylindrical portion 45c of the light shielding film 45 is extended to reach into the recess 21 of the silicon substrate 1, so that the light guide The entire outer periphery of the waveguide portion 49 is surrounded by the cylindrical portion 45 c of the light shielding film 45. Accordingly, even when light having an incident angle of less than ⁇ 46.5 [°] is incident on the interface between the core portion 47a and the cladding portion 46a, the light that has passed through the interface is Since the light is reflected by the cylindrical portion 45 c of the light shielding film 45, it is possible to prevent light from leaking from the outer periphery of the optical waveguide portion 49.
  • the solid-state imaging device 40 further suppresses deterioration in image quality by preventing light from leaking from the outer periphery of the optical waveguide portion 49, as compared with the solid-state imaging device 10 of the first embodiment.
  • the light collection efficiency to the photodiode 2 can be further increased.
  • FIG. 7 is a schematic cross-sectional view showing the main part of the solid-state imaging device 50.
  • the color filter layer 8 is provided on the high refractive index layer 7, whereas as shown in FIG. 7, the solid-state imaging device 10 according to Embodiment 2
  • the imaging device 50 is different in that the high refractive index layer 57 has a function as a color filter and no separate color filter layer is provided.
  • the same components as those of the solid-state imaging device 10 shown in FIG. 2 are denoted by the same reference numerals for the sake of simplicity, and the description thereof is omitted.
  • the high refractive index layer 57 is a color filter material having a refractive index higher than that of silicon oxide (refractive index 1.45) constituting the low refractive index layer 6, for example, an organic material (refractive index 1.7) in which pigments are dispersed. It consists of
  • the optical waveguide portion 59 includes a cladding portion 6 a of the low refractive index layer 6 and a core portion 57 a of the high refractive index layer 57.
  • the solid-state imaging device 50 since the high refractive index layer 57 has a function as a color filter, it is not necessary to provide a separate color filter layer, and the first embodiment described above is used. Compared to the solid-state imaging device 10, the microlens 51 can be brought closer to the photodiode 2 of the silicon substrate 1 by the thickness of the color filter layer. Thereby, the solid-state imaging device 50 can improve the numerical aperture (NA) of the lens and the light collection efficiency more than the solid-state imaging device 10 of the first embodiment.
  • NA numerical aperture
  • the radius of curvature of the microlens 51 is set to be smaller than the radius of curvature of the microlens 11 of the first embodiment, corresponding to the fact that the microlens 51 approaches the photodiode 2 and the condensing distance of the lens is shortened. Has been.
  • the work load and the cost can be reduced because the process of the color filter layer is not necessary in the manufacturing process.
  • FIG. 8 is a schematic cross-sectional view showing the main part of the solid-state imaging device 60.
  • the high refractive index layer 7 does not constitute an in-layer lens
  • the solid-state imaging device according to the fourth embodiment. 60 the upper surface of the high refractive index layer 67 is formed in a convex shape upward, and the outer peripheral surface of the core portion 67a of the high refractive index layer 67 is formed in a convex shape downward.
  • the high refractive index layer 67 constitutes an in-layer lens.
  • the same components as those of the solid-state imaging device 10 shown in FIG. 2 are denoted by the same reference numerals for the sake of simplicity, and the description thereof is omitted.
  • the inner diameter of the cylindrical clad portion 66a is gradually reduced from the upper end to the lower end of the clad portion 66a, and the inner peripheral surface 66a1 of the clad portion 66a is formed in a concave shape.
  • the low refractive index layer 66 is made of a reflow material, for example, BPSG (Boron Phosphorus Silicon Glass) (refractive index 1.45), and is formed by heat treatment.
  • the outer peripheral surface 67a1 of the core portion 67a has a convex shape along the inner peripheral surface 66a1 of the cladding portion 66a.
  • a convex portion 67b is provided in a region above the core portion 67a.
  • the core portion 67a forms a downward convex lens, and the convex portion 67b forms an upward convex lens. Therefore, the high refractive index layer 67 functions as an in-layer lens.
  • the high refractive index layer 67 is made of, for example, a silicon nitride film (refractive index 1.9).
  • the optical waveguide portion 69 is constituted by the clad portion 66a and the core portion 67a. Further, the light exit surface 69a of the optical waveguide portion 69 is a part of the outer peripheral surface 67a1 of the core portion 67a, and is constituted by a substantially planar portion (a portion indicated by a thick line in FIG. 8) including the lower end of the core portion 67a. ing.
  • the substantially planar portion constituting the light emitting surface 69a is a portion that can transmit incident light on the outer peripheral surface 67a1 of the core portion 67a with almost no reflection. Also in the present embodiment, the position Py of the light emitting surface 69a is set lower than the reference surface S of the silicon substrate 1.
  • a flattening layer 68 for flattening the upper surface is formed on the high refractive index layer 67, and the color filter layer 8 is formed on the flattening layer 68.
  • the solid-state imaging device 60 according to the fourth embodiment having the above-described configuration since the high refractive index layer 67 is configured as an inner lens, the light collection efficiency to the photodiode 2 can be further improved. .
  • the configuration of the substantially planar light emitting surface 69a is shown.
  • the present invention is not limited to this.
  • the light emitting surface may have a curved shape. As long as the entire light emitting surface is set lower than the reference surface S of the silicon substrate 1, it is possible to suppress deterioration in image quality due to diffracted light as compared with the conventional case.
  • the recess forming step is performed before the transfer electrode forming step and the second step of forming the light shielding film 5, whereas the manufacturing of the present embodiment is performed.
  • the method is different in that a recess forming step is performed after the second step. Note that the description of the same steps as those of the method of manufacturing the solid-state imaging device 10 shown in FIGS. 4 and 5 is omitted or simplified.
  • Step of forming transfer electrode and second insulating film >> Next, the vertical transfer electrode 4 is formed on the first insulating film 64a, and the second insulating film 64b is formed on the vertical transfer electrode 4 formed on the first insulating film 64a (FIG. 9B).
  • the recess 62 is formed by dry etching using the resist pattern 61 (FIG. 9C), and the entire formation region of the recess 62 is filled with the thermal oxide film 63 by thermal oxidation (FIG. 9). (D)) After that, the oxide film 63 and the resist pattern 61 are removed (FIG. 10A). As a result, the recess 21 is completed.
  • the low refractive index layer 6 is formed on the light shielding film 5, and further, p is formed along the inner peripheral surface of the recess 21 in the silicon substrate 1 by ion implantation.
  • a + layer 12 is formed (FIG. 10B).
  • the high refractive index layer 7 is formed on the low refractive index layer 6 (FIG. 10C). In this way, the optical waveguide part 20 comprised by the clad part 6a and the core part 7a is completed.
  • the low refractive index layer 6 is formed in the recess 21 along the inner peripheral surface of the recess 21.
  • the first and second insulating films 64a and 64b are formed before the recess forming step, and the recesses in the first and second insulating films 64a and 64b are formed by dry etching in the recess forming step. This is because the portions in 21 are removed together, and there are no first and second insulating films 64a and 64b in the recess 21.
  • the subsequent steps are the same as the manufacturing method of the solid-state imaging device 10 according to the first embodiment.
  • the vertical transfer electrode 4 and the light shielding film 5 are formed before the recess 21 is formed. Therefore, the vertical transfer electrode 4 and the light shielding film 5 are formed after the recess 21 is formed. Compared with this, there is an advantage that the vertical transfer electrode 4 and the light shielding film 5 can be easily formed because the upper surface 1c of the silicon substrate 1 is not uneven.
  • the first and second insulating films and the antireflection film may be formed in the formed recess 21.
  • the recess forming step is performed before the transfer electrode forming step and the second step of forming the light shielding film 5, whereas the manufacturing of the present embodiment is performed.
  • the method is different in that a recess forming step is performed between the transfer electrode forming step and the second step. Note that the description of the same steps as those of the method of manufacturing the solid-state imaging device 10 shown in FIGS. 4 and 5 is omitted or simplified.
  • a concave portion 72 having a depth d2 is formed by dry etching using a resist pattern 71 made of silicon nitride (FIG. 11 (b)) and thermally oxidized.
  • the entire formation region of the recess 21 is filled with the thermal oxide film 73 (FIG. 11C), and then the oxide film 73 is removed (FIG. 11D). As a result, the recess 21 is completed.
  • the resist pattern 71 is left without being removed.
  • thermal oxide film 75 silicon oxide film
  • a second insulating film 74b is formed (FIG. 12A).
  • the point that the thermal oxidation film is formed by thermally oxidizing the inner peripheral surface of the recess 21 in this way, and the point that the insulating film made of silicon oxynitride is used for the second insulating film are the same as in the first embodiment. Is different.
  • a P + layer 12 is formed in the silicon substrate 1 along the inner peripheral surface of the recess 21 by ion implantation (FIG. 12A).
  • the vertical transfer electrode 4 is formed before the recess 21 is formed, and therefore, compared with the case where the vertical transfer electrode 4 is formed after the recess 21 is formed. There is an advantage that the vertical transfer electrode 4 can be easily formed because there is no unevenness on the upper surface 1c of the first electrode.
  • the inner peripheral surface of the concave portion 21 is thermally oxidized after the concave portion forming step, so that the silicon crystal defects generated on the inner peripheral surface of the concave portion 21 can be recovered.
  • the configuration in which the photoelectric conversion unit is made of a photodiode is shown, but the configuration of the photoelectric conversion unit is not limited.
  • silicon oxide is used as the transparent material having the first refractive index and silicon nitride is used as the transparent material having the second refractive index.
  • the refractive index of the transparent material having the second refractive index is higher than that of the material, and the present invention is not limited to this.
  • the transparent material having the first refractive index may be silicon oxide
  • the transparent material having the second refractive index may be silicon oxynitride (refractive index: 1.6 to 2).
  • the depth d1 of the recess 21 is about 220 [nm] and the depth d2 of the light emitting surface 20a of the optical waveguide section 20 is about 100 [nm].
  • the present invention is not limited to this. Absent. The lower the position of the light exit surface of the optical waveguide portion than the reference surface of the silicon substrate, the smaller the amount of light incident on the vicinity of the transfer channel due to diffraction and the higher the noise charge reduction effect.
  • the recess deeper, for example, the silicon crystal defects on the inner peripheral surface of the recess increase, or a high voltage is required to read the signal charge because the photodiode is separated from the transfer channel. I get out. Therefore, it is preferable to appropriately set the depth of the light exit surface and the depth of the recess depending on the specifications of the solid-state imaging device.
  • the silicon substrate includes the n-type region and the p-type well region, and the photodiode and the vertical transfer channel are formed in the p-type well region.
  • the present invention is limited to this. It is not a thing.
  • the manufacturing method of the solid-state imaging device according to the present invention has been described, but the manufacturing method of the solid-state imaging device is not particularly limited.
  • the manufacturing method can be appropriately selected according to the specification or application of the solid-state imaging device.
  • the present invention is useful for realizing a high-quality solid-state imaging device.
  • Silicon substrate 1a n-type region 1b. p-type well region 1c. Upper surface 2. Photodiode 3a, 3b. Vertical transfer channel 4. 4. Vertical transfer electrode Light shielding film 5a. Opening 5b. Plate-like part 5c. Cylindrical part 6. Low refractive index layer 6a. Clad part 7. High refractive index layer 7a. Core part 8. Color filter layer 10. Solid-state imaging device 11. Microlens 13. Antireflection film 20. Optical waveguide portion 20a. Light exit surface 20c. Lower end 21. Recess 40, 50, 60. Solid-state imaging device 66a. Clad part 66a1. Inner peripheral surface 67. High refractive index layer 67a. Core part 67a1. Outer peripheral surface Reference plane

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Abstract

Disclosed is a solid-state image pickup device which is provided with: a silicon substrate (1), which is provided with a photodiode (2) and a vertical transfer channel (3); a light blocking film (5), which covers the upper surface (1c) of the silicon substrate (1), and has an opening (5a) provided in a region that corresponds to the photodiode (2); and an optical waveguide section (20), which is composed of a cladding portion (6a) and a core portion (7a), said cladding portion and core portion being provided in the opening (5a) and having different refractive indexes, and which guides downward the light inputted from above and outputs the light from a light outputting surface (20a). The silicon substrate (1) region that corresponds to the vertical transfer channel (3), said region being on the upper surface (1c), is specified as a reference surface (S), a recessed section (21) that forms a step lower than the reference surface (S) is provided in the upper surface (1c) region that corresponds to the photodiode (2), and the light outputting surface (20a) of the optical waveguide section (20) is disposed in the recessed section (21) on the silicon substrate (1), thereby having the light outputting surface (20a) lower than the reference surface (S) of the silicon substrate (1).

Description

固体撮像装置及びその製造方法Solid-state imaging device and manufacturing method thereof
　本発明は、固体撮像装置及びその製造方法に関し、特に画質の劣化を抑制する技術に関する。 The present invention relates to a solid-state imaging device and a method for manufacturing the same, and particularly to a technique for suppressing deterioration in image quality.
　近年、デジタルスチルカメラ、デジタルムービカメラや携帯電話機などに固体撮像装置が用いられている。これらの機器が普及するにつれて、固体撮像装置に対する高解像度化や多画素化の要求が高まり、画素の小型化が進められている。 In recent years, solid-state imaging devices have been used for digital still cameras, digital movie cameras, mobile phones, and the like. As these devices become widespread, demands for higher resolution and a larger number of pixels for solid-state imaging devices have increased, and pixel miniaturization has been promoted.
　このような固体撮像装置は、各画素の位置に設けられた光電変換部および当該光電変換部により変換された電荷を転送する転送チャネルが設けられた半導体基板と、半導体基板の上面を覆いかつ光電変換部に相当する領域に開口部が設けられた遮光膜とを有している。また、光電変換部への集光効率を高めるために、遮光膜の開口部内に、上方から入射された光を下方に導き光出射面から出射し、光電変換部に導く光導波路部を備えたものがある（例えば、特許文献１参照）。かかる光導波路部の光出射面は、半導体基板の上面よりも高い位置に配置されている。 Such a solid-state imaging device includes a photoelectric conversion unit provided at the position of each pixel, a semiconductor substrate provided with a transfer channel for transferring charges converted by the photoelectric conversion unit, and an upper surface of the semiconductor substrate and a photoelectric conversion unit. And a light-shielding film having an opening in a region corresponding to the conversion unit. In addition, in order to increase the light collection efficiency to the photoelectric conversion unit, an optical waveguide unit is provided in the opening of the light-shielding film to guide light incident from above to emit downward from the light exit surface and guide it to the photoelectric conversion unit. There are some (see, for example, Patent Document 1). The light emitting surface of the optical waveguide portion is arranged at a position higher than the upper surface of the semiconductor substrate.
特開２００３－６０１７９号公報Japanese Patent Laid-Open No. 2003-60179
　上記従来の固体撮像装置では、光導波路部内を導かれてきた光は、光出射面から出射されるときに光出射面で回折する。また、近年の画素の小型化により遮光膜の開口幅が１［μｍ］以下と小さくなり、それに伴い光導波路部の光出射面の幅が１［μｍ］以下になっている。この光出射面の幅が光の波長に近づけば近づくほど、光出射面で生じる光の回折は大きくなる。そのため、回折光の一部が、半導体基板内において転送チャネル側に回り込み、転送チャネル付近で光による電荷が発生する場合がある。 In the above-described conventional solid-state imaging device, the light guided through the optical waveguide portion is diffracted by the light exit surface when it is emitted from the light exit surface. In addition, with the recent miniaturization of pixels, the opening width of the light shielding film is reduced to 1 [μm] or less, and accordingly, the width of the light exit surface of the optical waveguide portion is 1 [μm] or less. The closer the width of this light exit surface is to the wavelength of light, the greater the diffraction of light that occurs on the light exit surface. For this reason, a part of the diffracted light may circulate toward the transfer channel in the semiconductor substrate and light may be generated near the transfer channel.
　そして、この発生した電荷が、転送チャネルに移動した場合には、転送チャネル内で転送される、他の光電変換部で生成された信号電荷に混ざり込むノイズ電荷となって、画質が劣化するという問題が生じる。 When the generated charge moves to the transfer channel, it becomes noise charge mixed in the signal charge generated in another photoelectric conversion unit transferred in the transfer channel, and the image quality is deteriorated. Problems arise.
　本発明は、上記した課題に鑑み、従来よりも回折光による画質の劣化を抑制することができる固体撮像装置及びその製造方法を提供することを目的とする。 In view of the above-described problems, an object of the present invention is to provide a solid-state imaging device capable of suppressing deterioration in image quality due to diffracted light and a manufacturing method thereof.
　上記課題を解決するために、本発明に係る固体撮像装置は、光電変換部および当該光電変換部により変換された電荷を転送する転送チャネルが設けられた半導体基板と、前記半導体基板の上面を覆いかつ前記光電変換部に相当する領域に開口部が設けられた遮光膜と、前記開口部内に設けられた屈折率の異なる複数の透明材料からなり、上方から入射された光を下方に導き光出射面から出射させる光導波路部とを備え、前記半導体基板の上面の前記転送チャネルに相当する領域を基準面として、当該上面の前記光電変換部に相当する領域に、前記基準面よりも低い凹部が設けられ、前記光導波路部の光出射面が前記半導体基板の凹部内に配置されることにより、当該光出射面が前記半導体基板の基準面よりも低い位置にあることを特徴とする。 In order to solve the above problems, a solid-state imaging device according to the present invention covers a photoelectric conversion unit, a semiconductor substrate provided with a transfer channel for transferring charges converted by the photoelectric conversion unit, and an upper surface of the semiconductor substrate. And a light shielding film having an opening provided in a region corresponding to the photoelectric conversion unit and a plurality of transparent materials having different refractive indexes provided in the opening, and guides light incident from above to emit light. An optical waveguide portion that emits from a surface, and a region corresponding to the transfer channel on the upper surface of the semiconductor substrate is a reference surface, and a recess that is lower than the reference surface is formed in a region corresponding to the photoelectric conversion portion on the upper surface And the light emitting surface of the optical waveguide portion is disposed in the recess of the semiconductor substrate so that the light emitting surface is at a position lower than the reference surface of the semiconductor substrate. .
　また、本発明に係る固体撮像装置の製造方法は、半導体基板内に、光電変換部および当該光電変換部により変換された電荷を転送する転送チャネルを形成する第１の工程と、前記半導体基板の上面を覆いかつ前記光電変換部に相当する領域に開口部が設けられた遮光膜を形成する第２の工程と、前記遮光膜の開口部内に、屈折率の異なる複数の透明材料からなり、上方から入射された光を下方に導き光出射面から出射させる光導波路部を形成する第３の工程とを有する方法であって、前記第１の工程と前記第３の工程との間に、さらに、前記半導体基板の上面の前記転送チャネルに相当する領域を基準面として、当該上面の前記光電変換部に相当する領域に、前記基準面よりも低い凹部を形成する凹部形成工程を有し、前記第３の工程において、前記光導波路部の光出射面を前記半導体基板の凹部内に配置して、当該光出射面の位置を前記半導体基板の基準面よりも低くすることを特徴とする。 In addition, the method for manufacturing a solid-state imaging device according to the present invention includes a first step of forming a photoelectric conversion unit and a transfer channel for transferring a charge converted by the photoelectric conversion unit in a semiconductor substrate; A second step of forming a light-shielding film covering an upper surface and having an opening provided in a region corresponding to the photoelectric conversion unit; and the opening of the light-shielding film is made of a plurality of transparent materials having different refractive indexes, A third step of forming an optical waveguide portion that guides light incident from below and emits the light from the light exit surface, wherein the method further includes a step between the first step and the third step. A step of forming a recess that is lower than the reference surface in a region corresponding to the photoelectric conversion part on the upper surface, with a region corresponding to the transfer channel on the upper surface of the semiconductor substrate as a reference surface, In the third step Te, place the light exit surface of the optical waveguide portion into the recess of the semiconductor substrate, characterized by the position of the light emitting surface lower than the reference surface of the semiconductor substrate.
　上記構成の固体撮像装置では、半導体基板の上面の転送チャネルに相当する領域を基準面として、当該上面の光電変換部に相当する領域に基準面よりも低い凹部を設け、凹部内に、光導波路部の光出射面を配置することにより、当該光出射面の位置を半導体基板の基準面よりも低くしている。 In the solid-state imaging device having the above configuration, a region corresponding to the transfer channel on the upper surface of the semiconductor substrate is used as a reference surface, and a recess that is lower than the reference surface is provided in a region corresponding to the photoelectric conversion unit on the upper surface. By arranging the light emitting surface of the part, the position of the light emitting surface is made lower than the reference surface of the semiconductor substrate.
　一方、従来の固体撮像装置では、光の回折が生じる光出射面が半導体基板の上面（基準面）よりも高い位置にある。 On the other hand, in the conventional solid-state imaging device, the light exit surface where light diffraction occurs is located higher than the upper surface (reference surface) of the semiconductor substrate.
　これにより、光の回折が生じる光出射面の位置が、半導体基板の上面（基準面）よりも高い位置にある従来の固体撮像装置と比べて低くなる分、半導体基板内のより深い位置において光が拡がるようになる。そのため、転送チャネル側に回り込む光が、半導体基板内のより深い位置、すなわち転送チャネルからより離れた位置を通過するようになり、従来よりも、転送チャネル付近に入射する光の量が少なくなる。 As a result, the position of the light emitting surface where light is diffracted is lower than that of a conventional solid-state imaging device located at a position higher than the upper surface (reference surface) of the semiconductor substrate. Will spread. For this reason, light that travels to the transfer channel side passes through a deeper position in the semiconductor substrate, that is, a position farther from the transfer channel, and the amount of light that enters the vicinity of the transfer channel becomes smaller than in the past.
　これにより、転送チャネル付近で、光により発生する電荷が少なくなるので、転送チャネル内の信号電荷に混ざり込むノイズ電荷を低減でき、画質の劣化を抑制することができる。 As a result, the charge generated by light in the vicinity of the transfer channel is reduced, so that noise charges mixed with the signal charge in the transfer channel can be reduced, and deterioration of image quality can be suppressed.
　上記構成の固体撮像装置の製造方法によれば、上記固体撮像装置と同様の効果を得ることができる。 According to the method for manufacturing a solid-state imaging device having the above configuration, the same effects as those of the solid-state imaging device can be obtained.
本発明の実施の形態１に係る固体撮像装置１０の概略構成を示す模式ブロック図である。1 is a schematic block diagram showing a schematic configuration of a solid-state imaging device 10 according to Embodiment 1 of the present invention. 本発明の実施の形態１に係る固体撮像装置１０の撮像画素部１０ａの構成を示す模式断面図である。It is a schematic cross section which shows the structure of the imaging pixel part 10a of the solid-state imaging device 10 concerning Embodiment 1 of this invention. （ａ）は、参考としての従来技術に係る固体撮像装置での回折光の一例を示す図であり、（ｂ）は、固体撮像装置１０における回折光の一例を示す図である。(A) is a figure which shows an example of the diffracted light in the solid-state imaging device which concerns on the prior art as a reference, (b) is a figure which shows an example of the diffracted light in the solid-state imaging device 10. 固体撮像装置１０の製造における一部の工程を示す模式断面図である。3 is a schematic cross-sectional view showing some steps in manufacturing the solid-state imaging device 10. FIG. 固体撮像装置１０の製造における一部の工程を示す模式断面図である。3 is a schematic cross-sectional view showing some steps in manufacturing the solid-state imaging device 10. FIG. 本発明の実施の形態２に係る固体撮像装置４０の要部を示す模式断面図である。It is a schematic cross section which shows the principal part of the solid-state imaging device 40 concerning Embodiment 2 of this invention. 本発明の実施の形態３に係る固体撮像装置５０の要部を示す模式断面図である。It is a schematic cross section which shows the principal part of the solid-state imaging device 50 concerning Embodiment 3 of this invention. 本発明の実施の形態４に係る固体撮像装置６０の要部を示す模式断面図である。It is a schematic cross section which shows the principal part of the solid-state imaging device 60 which concerns on Embodiment 4 of this invention. 本発明の実施の形態５に係る固体撮像装置の製造における一部工程を示す模式断面図である。It is a schematic cross section which shows a part process in manufacture of the solid-state imaging device concerning Embodiment 5 of this invention. 本発明の実施の形態５に係る固体撮像装置の製造における一部工程を示す模式断面図である。It is a schematic cross section which shows a part process in manufacture of the solid-state imaging device concerning Embodiment 5 of this invention. 本発明の実施の形態６に係る固体撮像装置の製造における一部工程を示す模式断面図である。It is a schematic cross section which shows a partial process in manufacture of the solid-state imaging device which concerns on Embodiment 6 of this invention. 本発明の実施の形態６に係る固体撮像装置の製造における一部工程を示す模式断面図である。It is a schematic cross section which shows a partial process in manufacture of the solid-state imaging device which concerns on Embodiment 6 of this invention.
　以下では、本発明を実施するための形態について、図面を参酌しながら説明する。なお、以下の各実施の形態は、本発明の構成およびそこから奏される作用・効果を分かり易く説明するために用いる例であって、本発明は、本質的な特徴部分以外に何ら以下の形態に限定を受けるものではない。 Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. Each of the following embodiments is an example used for easily explaining the configuration of the present invention and the operations and effects produced therefrom, and the present invention is not limited to the following essential features. The form is not limited.
　以下に、本発明の実施の形態について、図面を参照して具体的に説明する。 Hereinafter, embodiments of the present invention will be specifically described with reference to the drawings.
　［実施の形態１］
　１．全体構成
　本実施の形態１に係る固体撮像装置１０の全体構成について、図１を用い説明する。 [Embodiment 1]
1. Overall Configuration The overall configuration of the solid-state imaging device 10 according to the first embodiment will be described with reference to FIG.
　図１に示すように、本実施の形態１に係る固体撮像装置１０は、マトリクス状に配された複数の撮像画素部１０ａと、Ｙ軸方向に延伸配置された垂直ＣＣＤ部１０ｂと、Ｘ軸方向に延伸配置された水平ＣＣＤ部１０ｃと、これに続くアンプ部１０ｄなどが形成されてなる。このように、本実施の形態では、その一例として、インターライン（ＩＴ）－ＣＣＤ型固体撮像装置の構成を採用する。 As shown in FIG. 1, the solid-state imaging device 10 according to the first embodiment includes a plurality of imaging pixel units 10a arranged in a matrix, a vertical CCD unit 10b extending in the Y-axis direction, and an X-axis. A horizontal CCD unit 10c extending in the direction and an amplifier unit 10d following the horizontal CCD unit 10c are formed. Thus, in this embodiment, as an example, the configuration of an interline (IT) -CCD type solid-state imaging device is employed.
　撮像画素部１０ａでは、光電変換により、入射光量に応じた電荷を生成する。 In the imaging pixel unit 10a, a charge corresponding to the amount of incident light is generated by photoelectric conversion.
　垂直ＣＣＤ部１０ｂは、各列の撮像画素部１０ａに対して隣接形成されており、撮像画素部１０ａで生成された信号電荷を受け、Ｙ軸方向下方へと転送する機能を有する。垂直ＣＣＤ部１０ｂにおける信号電荷は、並列的に順次水平ＣＣＤ部１０ｃへ移され、アンプ部１０ｄを介し出力される。 The vertical CCD unit 10b is formed adjacent to the imaging pixel unit 10a of each column, and has a function of receiving a signal charge generated by the imaging pixel unit 10a and transferring it downward in the Y-axis direction. The signal charges in the vertical CCD unit 10b are sequentially transferred to the horizontal CCD unit 10c in parallel and output through the amplifier unit 10d.
　２．撮像画素部１０ａの構成
　撮像画素部１０ａおよびその周辺部分の構成について、図２を用い説明する。 2. Configuration of Imaging Pixel Unit 10a The configuration of the imaging pixel unit 10a and its peripheral part will be described with reference to FIG.
　図２（ａ）に示すように、固体撮像装置１０は、半導体基板としてのシリコン基板１を有している。シリコン基板１は、ｎ型領域１ａと、ｎ型領域１ａの上に設けられたｐ型ウェル領域１ｂとからなり、ｐ型ウェル領域１ｂ内に、フォトダイオード２が形成されている。ｐ型ウェル領域１ｂ内におけるフォトダイオード２の一方側には、フォトダイオード２からの信号電荷を転送する垂直転送チャネル３ａが形成されており、フォトダイオード２の他方側には、隣接する他のフォトダイオードからの信号電荷を転送する垂直転送チャネル３ｂが形成されている。 As shown in FIG. 2A, the solid-state imaging device 10 has a silicon substrate 1 as a semiconductor substrate. The silicon substrate 1 includes an n-type region 1a and a p-type well region 1b provided on the n-type region 1a. A photodiode 2 is formed in the p-type well region 1b. A vertical transfer channel 3a for transferring signal charges from the photodiode 2 is formed on one side of the photodiode 2 in the p-type well region 1b, and another adjacent photo diode is formed on the other side of the photodiode 2. A vertical transfer channel 3b for transferring signal charges from the diode is formed.
　また、ｐ型ウェル領域１ｂ内のフォトダイオード２上には、シリコン基板１の上面１ｃに沿ってｐ+層１２が形成されている。 A p + layer 12 is formed along the upper surface 1c of the silicon substrate 1 on the photodiode 2 in the p-type well region 1b.
　シリコン基板１上には、酸化シリコンからなる第１絶縁膜１４ａが形成されている。第１絶縁膜１４ａは、シリコン基板１のｐ+層１２上の領域、すなわちフォトダイオード２に相当する領域の薄膜部分１４ａ１と、垂直転送チャネル３ａ，３ｂに相当する領域の厚膜部分１４ａ２とからなる。 On the silicon substrate 1, a first insulating film 14a made of silicon oxide is formed. The first insulating film 14a includes a thin film portion 14a1 in a region on the p + layer 12 of the silicon substrate 1, that is, a region corresponding to the photodiode 2, and a thick film portion 14a2 in a region corresponding to the vertical transfer channels 3a and 3b. Become.
　第１絶縁膜１４ａにおける厚膜部分１４ａ２上には、多結晶シリコンからなる垂直転送電極４が形成されている。また、第１絶縁膜１４ａにおける薄膜部分１４ａ１上には、窒化シリコンからなる反射防止膜１３が形成されている。 A vertical transfer electrode 4 made of polycrystalline silicon is formed on the thick film portion 14a2 of the first insulating film 14a. An antireflection film 13 made of silicon nitride is formed on the thin film portion 14a1 of the first insulating film 14a.
　第１絶縁膜１４ａ上に形成された垂直転送電極４および反射防止膜１３上には、酸化シリコンからなる第２絶縁膜１４ｂが形成されている。 A second insulating film 14b made of silicon oxide is formed on the vertical transfer electrode 4 and the antireflection film 13 formed on the first insulating film 14a.
　第２絶縁膜１４ｂ上には、シリコン基板１の上面を覆うアルミニウムなどの金属材料からなる遮光膜５が形成されている。遮光膜５には、フォトダイオード２に相当する領域に開口部５ａが設けられている。遮光膜５は、垂直転送電極４の上面に沿って形成された板状部分５ｂと、垂直転送電極４の側面に沿うように、板状部分５ｂの開口縁から下方に向かって延設された筒状部分５ｃとからなる。 On the second insulating film 14b, a light shielding film 5 made of a metal material such as aluminum covering the upper surface of the silicon substrate 1 is formed. The light shielding film 5 is provided with an opening 5 a in a region corresponding to the photodiode 2. The light shielding film 5 extends downward from the opening edge of the plate-like portion 5 b so as to follow the plate-like portion 5 b formed along the upper surface of the vertical transfer electrode 4 and the side surface of the vertical transfer electrode 4. It consists of the cylindrical part 5c.
　第２絶縁膜１４ｂ上に形成された遮光膜５上には、第１の屈折率の透明材料、例えば酸化シリコン（屈折率１．４５）からなる低屈折率層６が形成されている。低屈折率層６の厚みは、１００［ｎｍ］程度である。低屈折率層６は、遮光膜５の存在する領域では遮光膜５の表面に沿って形成され、遮光膜５の存在しない領域、すなわちフォトダイオード２に相当する領域では、第２絶縁膜１４ｂの表面に沿って形成されている。 A low refractive index layer 6 made of a transparent material having a first refractive index, for example, silicon oxide (refractive index 1.45) is formed on the light shielding film 5 formed on the second insulating film 14b. The thickness of the low refractive index layer 6 is about 100 [nm]. The low refractive index layer 6 is formed along the surface of the light shielding film 5 in the region where the light shielding film 5 exists, and in the region where the light shielding film 5 does not exist, that is, in the region corresponding to the photodiode 2, the second insulating film 14 b. It is formed along the surface.
　低屈折率層６上には、第１の屈折率よりも高い第２の屈折率の透明材料、例えば窒化シリコン（屈折率２．０）からなる高屈折率層７が形成されている。高屈折率層７は、遮光膜５の開口部５ａの内部を埋め尽くして上面が平坦になるのに十分な厚みに形成されている。 On the low refractive index layer 6, a high refractive index layer 7 made of a transparent material having a second refractive index higher than the first refractive index, for example, silicon nitride (refractive index 2.0) is formed. The high refractive index layer 7 is formed with a thickness sufficient to fill the inside of the opening 5a of the light shielding film 5 and flatten the upper surface.
　高屈折率層７上には、有機材料に顔料が分散されたカラーフィルタ層８が形成されている。 On the high refractive index layer 7, a color filter layer 8 in which a pigment is dispersed in an organic material is formed.
　カラーフィルタ層８上には、上面を平坦化するための平坦化層９が形成されている。 On the color filter layer 8, a flattening layer 9 for flattening the upper surface is formed.
　平坦化層９上には、入射光をフォトダイオード２に集光するマイクロレンズ１１が形成されている。 On the planarizing layer 9, a microlens 11 for condensing incident light on the photodiode 2 is formed.
　上記の通り、遮光膜５の開口部５ａの内部には、低屈折率層６と高屈折率層７とが形成されている。低屈折率層６は、遮光膜５の表面に沿って形成されているので、遮光膜５の開口部５ａの内部において、遮光膜５の筒状部分５ｃの内周面に沿った筒状のクラッド部６ａが形成される。また、高屈折率層７は、遮光膜５の開口部５ａの内部において、低屈折率層６のクラッド部６ａの筒内に埋め込まれてなるコア部７ａが形成される。これらクラッド部６ａおよびコア部７ａにより、入射光を上方から下方に導く光導波路部２０が構成される。 As described above, the low refractive index layer 6 and the high refractive index layer 7 are formed in the opening 5a of the light shielding film 5. Since the low refractive index layer 6 is formed along the surface of the light shielding film 5, a cylindrical shape along the inner peripheral surface of the cylindrical portion 5 c of the light shielding film 5 is formed inside the opening 5 a of the light shielding film 5. A clad portion 6a is formed. In the high refractive index layer 7, a core portion 7 a is formed inside the opening 5 a of the light shielding film 5 and is embedded in the cylinder of the cladding portion 6 a of the low refractive index layer 6. The clad portion 6a and the core portion 7a constitute an optical waveguide portion 20 that guides incident light downward from above.
　なお、本明細書において、垂直転送チャネル３ａ，３ｂをまとめて「垂直転送チャネル３」と称する場合もある。 In this specification, the vertical transfer channels 3a and 3b may be collectively referred to as “vertical transfer channel 3”.
　３．詳細構成
　以下、光導波路部２０の構成について、図２（ａ）の破線で囲んだ部分を拡大した図２（ｂ）を参照しながら詳しく説明する。 3. Detailed Configuration Hereinafter, the configuration of the optical waveguide unit 20 will be described in detail with reference to FIG. 2B in which a portion surrounded by a broken line in FIG.
　光導波路部２０において、コア部７ａの下端面が光出射面２０ａであり、光導波路部２０は、上方から入射した光を光出射面２０ａから出射して、フォトダイオード２に導くことができる。なお、図２（ｂ）では、分かり易くするため、光出射面２０ｂが太い線で示されている。 In the optical waveguide portion 20, the lower end surface of the core portion 7a is a light emitting surface 20a, and the optical waveguide portion 20 can emit light incident from above from the light emitting surface 20a and guide it to the photodiode 2. In FIG. 2B, the light exit surface 20b is shown by a thick line for easy understanding.
　光導波路部２０内では、屈折率の異なるコア部７ａとクラッド部６ａとの界面において、光を全反射させることができ、これにより、フォトダイオード２への集光効率を高めることができる。 In the optical waveguide part 20, light can be totally reflected at the interface between the core part 7a and the clad part 6a having different refractive indexes, and thereby the light collection efficiency to the photodiode 2 can be increased.
　光導波路部２０の下方では、シリコン基板１の上面１ｃにおけるフォトダイオード２に相当する領域に、上面１ｃの垂直転送チャネル３（図２（ａ）参照）に相当する領域を基準面Ｓとして、基準面Ｓよりも低い段差を形成する凹部２１が設けられている。 Below the optical waveguide portion 20, a region corresponding to the photodiode 2 on the upper surface 1 c of the silicon substrate 1 is used as a reference surface S, and a region corresponding to the vertical transfer channel 3 (see FIG. 2A) on the upper surface 1 c is used as a reference surface S. A recess 21 that forms a step lower than the surface S is provided.
　光導波路部２０は、遮光膜５の開口部５ａの内部からシリコン基板１の凹部２１内に至るまで設けられており、光導波路部２０の光出射面２０ａがシリコン基板１の凹部２１内に配置されている。このようにして、光導波路部２０の光出射面２０ａの位置（図２（ｂ）に示すＰｙ）を、シリコン基板１の基準面Ｓの位置（図２（ｂ）に示すＰｘ）よりも低くしている。 The optical waveguide portion 20 is provided from the inside of the opening 5 a of the light shielding film 5 to the concave portion 21 of the silicon substrate 1, and the light emitting surface 20 a of the optical waveguide portion 20 is disposed in the concave portion 21 of the silicon substrate 1. Has been. In this way, the position of the light emitting surface 20a of the optical waveguide portion 20 (Py shown in FIG. 2B) is set lower than the position of the reference surface S of the silicon substrate 1 (Px shown in FIG. 2B). is doing.
　本実施形態において、凹部２１の深さｄ１は２２０［ｎｍ］程度であり、基準面Ｓからの光出射面２０ａの深さｄ２は１００［ｎｍ］程度である。また、第１絶縁膜１４ａにおける薄膜部分１４ａ１の膜厚が２０［ｎｍ］程度、反射防止膜１３の膜厚が５０［ｎｍ］程度、第２絶縁膜１４ｂの膜厚が５０［ｎｍ］程度である。 In the present embodiment, the depth d1 of the recess 21 is about 220 [nm], and the depth d2 of the light emitting surface 20a from the reference plane S is about 100 [nm]. The thickness of the thin film portion 14a1 in the first insulating film 14a is about 20 [nm], the thickness of the antireflection film 13 is about 50 [nm], and the thickness of the second insulating film 14b is about 50 [nm]. is there.
　４．作用効果
　上記構成の固体撮像装置１０では、マイクロレンズ１１からの入射光が光導波路部２０を通過するときに、光導波路部２０の光出射面２０ａで光の回折が生じるが、光出射面２０ａの位置をシリコン基板１の基準面Ｓよりも低くすることにより、従来の固体撮像装置よりも回折光による画質の劣化を抑制することができる。 4). In the solid-state imaging device 10 having the above configuration, when incident light from the microlens 11 passes through the optical waveguide portion 20, light is diffracted on the light emission surface 20a of the optical waveguide portion 20, but the light emission surface 20a. Is made lower than the reference plane S of the silicon substrate 1, it is possible to suppress deterioration in image quality due to diffracted light as compared with the conventional solid-state imaging device.
　この回折光による画質の劣化を抑制する効果について、図３を参照しながら詳しく説明する。 The effect of suppressing the deterioration of image quality due to the diffracted light will be described in detail with reference to FIG.
　図３（ａ）は、従来の固体撮像装置における光導波路部の光出射面で回折する光の一例を示す図であり、図３（ｂ）は、本実施形態の固体撮像装置１０における光導波路部の光出射面で回折する光の一例を示す図である。 FIG. 3A is a diagram illustrating an example of light diffracted by the light exit surface of the optical waveguide portion in the conventional solid-state imaging device, and FIG. 3B is an optical waveguide in the solid-state imaging device 10 of the present embodiment. It is a figure which shows an example of the light diffracted by the light-projection surface of a part.
　図３（ａ）に示すように、従来の固体撮像装置９０では、遮光膜９５の開口部９５ａ内に設けられた、低屈折率層９６のクラッド部９６ａおよび高屈折率層９７のコア部９７ａからなる光導波路部９９の光出射面９９ａの位置Ｐ９が、シリコン基板９１の上面９１ａ（基準面）の位置Ｐｘよりも高い。このため、入射光Ｌ９のように、光導波路部９９の光出射面９９ａで回折した光は、シリコン基板９１の上面９１ａ（基準面）を通過するときには既に拡がりを有している。 As shown in FIG. 3A, in the conventional solid-state imaging device 90, the clad portion 96a of the low refractive index layer 96 and the core portion 97a of the high refractive index layer 97 provided in the opening 95a of the light shielding film 95. The position P9 of the light emitting surface 99a of the optical waveguide part 99 made of is higher than the position Px of the upper surface 91a (reference surface) of the silicon substrate 91. For this reason, like the incident light L9, the light diffracted by the light exit surface 99a of the optical waveguide portion 99 has already spread when passing through the upper surface 91a (reference surface) of the silicon substrate 91.
　これに対して、本実施形態の固体撮像装置１０では、図３（ｂ）に示すように、光導波路部２０の光出射面２０ａがシリコン基板１の凹部２１内に配置されることにより、光出射面２０ａの位置Ｐｙが、シリコン基板１の基準面Ｓの位置Ｐｘよりも低いので、入射光Ｌ１のように、シリコン基板１の基準面Ｓの位置Ｐｘを通過するときには回折による拡がりはなく、基準面Ｓよりも低い光出射面２０ａから出射されるときに回折により拡がるようになる。 On the other hand, in the solid-state imaging device 10 of the present embodiment, as shown in FIG. 3B, the light emission surface 20a of the optical waveguide portion 20 is disposed in the concave portion 21 of the silicon substrate 1, so that the light Since the position Py of the emission surface 20a is lower than the position Px of the reference surface S of the silicon substrate 1, there is no spread due to diffraction when passing through the position Px of the reference surface S of the silicon substrate 1 as in the incident light L1. When the light exits from the light exit surface 20a lower than the reference surface S, it spreads by diffraction.
　したがって、回折光が、従来よりもシリコン基板１内のより深い位置で拡がるようになるので、垂直転送チャネル３ａ側に回り込むとしても、シリコン基板１内のより深い位置、すなわち垂直転送チャネル３ａからより離れた位置を通過するようになり、垂直転送チャネル３ａ付近に入射する光の量を少なくすることができる。 Therefore, since the diffracted light spreads at a deeper position in the silicon substrate 1 than in the prior art, even if it wraps around the vertical transfer channel 3a side, it is more deep from the silicon substrate 1, that is, from the vertical transfer channel 3a. The amount of light incident on the vicinity of the vertical transfer channel 3a can be reduced by passing through a distant position.
　このようにして、垂直転送チャネル３付近に入射する光の量を少なくすれば、垂直転送チャネル３付近で光により発生する電荷も少なくなり、垂直転送チャネル３内の信号電荷に混ざり込むノイズ電荷を低減することができる。その結果として、画質の劣化を抑制することができるのである。 In this way, if the amount of light incident near the vertical transfer channel 3 is reduced, the charge generated by light near the vertical transfer channel 3 is also reduced, and noise charges mixed with the signal charge in the vertical transfer channel 3 are reduced. Can be reduced. As a result, image quality deterioration can be suppressed.
　以下に、光の回折が生じる光出射面の位置と、ノイズ電荷の低減との関係についてさらに詳しく説明する。 Hereinafter, the relationship between the position of the light exit surface where light diffraction occurs and the reduction of noise charge will be described in more detail.
　図３（ｂ）には、シリコン基板１内において、光により発生した電荷が、発生した位置によりフォトダイオード２、垂直転送チャネル３、およびＮ型領域１ａのうち何れの方に移動するかの境界を示す線Ｂ１，Ｂ２，Ｂ３が二点差線で引かれている。この境界線Ｂ１，Ｂ２，Ｂ３は、シリコン基板１内の電位分布によって決まるものである。フォトダイオード２、垂直転送チャネル３、およびＮ型領域１ａの各間において、Ｐ型ウェル領域１ｂが電位障壁として機能しており、その電位障壁の最も高いところを結んだ線が境界線Ｂ１，Ｂ２，Ｂ３である。 FIG. 3B shows a boundary on which of the photodiode 2, the vertical transfer channel 3 and the N-type region 1a the charge generated by light moves in the silicon substrate 1 depending on the position where the charge is generated. The lines B1, B2 and B3 showing are drawn with a two-point difference line. The boundary lines B1, B2, and B3 are determined by the potential distribution in the silicon substrate 1. The P-type well region 1b functions as a potential barrier between the photodiode 2, the vertical transfer channel 3, and the N-type region 1a, and the lines connecting the highest potential barriers are the boundary lines B1, B2. , B3.
　光導波路部２０の光出射面２０ａから出射された光のうち、その大部分が、境界線Ｂ１，Ｂ２，Ｂ３に囲まれた領域に入射し、例えば、入射光Ｌ１のように、当該領域で電荷ｅに変換される。こうして発生した電荷ｅは、電位勾配によりフォトダイオード２へと移動し、フォトダイオード２に集められて信号電荷となる。 Most of the light emitted from the light exit surface 20a of the optical waveguide portion 20 is incident on a region surrounded by the boundary lines B1, B2, and B3. For example, the incident light L1 is incident on the region. It is converted into electric charge e. The charges e thus generated move to the photodiode 2 due to the potential gradient, and are collected by the photodiode 2 to become signal charges.
　また、光導波路部２０の光出射面２０ａから出射された光のうち、一部の光は、境界線Ｂ３を越えて、境界線Ｂ３の下側の領域に入射し、当該領域で電荷に変換される。ここで発生した電荷は、電位勾配によりＮ型領域１ａへと移動し、Ｎ型領域１ａから排出される。 In addition, some of the light emitted from the light exit surface 20a of the optical waveguide portion 20 enters the region below the boundary line B3 beyond the boundary line B3, and is converted into electric charge in the region. Is done. The charges generated here move to the N-type region 1a due to the potential gradient and are discharged from the N-type region 1a.
　残りの光は、境界線Ｂ１の内側（垂直転送チャネル３ａ側）の領域、または境界線Ｂ２の内側（垂直転送チャネル３ｂ側）の領域に入射し、当該入射した領域で電荷に変換される。境界線Ｂ１の内側で発生した電荷は、電位勾配により垂直転送チャネル３ａへと移動する。そのため、垂直転送チャネル３ａ内で転送される、他のフォトダイオードからの信号電荷に混ざり込むノイズ電荷となって、画質の劣化に繋がる。また、境界線Ｂ２の内側で発生した電荷は、電位勾配により垂直転送チャネル３ｂへと移動し、同様に、垂直転送チャネル３ｂ内で転送される、他のフォトダイオードからの信号電荷に混ざり込むノイズ電荷となって、画質の劣化に繋がる。 The remaining light is incident on a region inside the boundary line B1 (on the vertical transfer channel 3a side) or a region inside the boundary line B2 (on the vertical transfer channel 3b side), and is converted into electric charge in the incident region. The charges generated inside the boundary line B1 move to the vertical transfer channel 3a due to the potential gradient. For this reason, noise charges mixed in signal charges from other photodiodes transferred in the vertical transfer channel 3a are generated, leading to degradation of image quality. Further, the charge generated inside the boundary line B2 moves to the vertical transfer channel 3b due to the potential gradient, and similarly, noise mixed into signal charges from other photodiodes transferred in the vertical transfer channel 3b. It becomes electric charge and leads to deterioration of image quality.
　これらより、境界線Ｂ１およびＢ２の内側の領域に入射する光の量を少なくすることができれば、当該各領域において発生する電荷が少なくなるので、転送チャネル内で転送される、他のフォトダイオードの信号電荷に混ざり込むノイズ電荷を低減することができる。 Accordingly, if the amount of light incident on the regions inside the boundary lines B1 and B2 can be reduced, the charge generated in each region is reduced, so that other photodiodes transferred in the transfer channel Noise charges mixed with signal charges can be reduced.
　本発明者らは、回折光により境界線Ｂ１およびＢ２の内側の領域に入射する光の量を少なくするために、回折光がシリコン基板１内のより深い位置で拡がるようにし、それにより、垂直転送チャネル３ａ，３ｂ側に回り込む光を、境界線Ｂ１，Ｂ２の下側を通過させるようにすることを考えた。回折光がシリコン基板１内のより深い位置で拡がるようにするには、光の回折が生じる光出射面の位置を低くすれば良いが、従来の固体撮像装置９０では、単純に光出射面の位置を低くしようとしても、シリコン基板９１の上面９１ａ（基準面）の位置までと限界がある（図３（ａ）参照）。そこで、本発明者らは、シリコン基板１の上面１ｃに凹部２１を設け、凹部２１内に光導波路部２０の光出射面２０ａを配置することにより、光の回折が生じる光出射面２０ａの位置Ｐｙを、基準面Ｓの位置Ｐｘよりもさらに低くして、回折光がシリコン基板１内のより深い位置で拡がるようにした。 In order to reduce the amount of light incident on the regions inside the boundary lines B1 and B2 by the diffracted light, the inventors have made the diffracted light spread at a deeper position in the silicon substrate 1, thereby making the vertical It has been considered to allow the light that travels to the transfer channels 3a and 3b to pass below the boundary lines B1 and B2. In order to spread the diffracted light at a deeper position in the silicon substrate 1, the position of the light emitting surface where the light is diffracted may be lowered. However, in the conventional solid-state imaging device 90, the light emitting surface is simply Even if the position is to be lowered, there is a limit to the position of the upper surface 91a (reference surface) of the silicon substrate 91 (see FIG. 3A). Therefore, the present inventors provide a concave portion 21 on the upper surface 1c of the silicon substrate 1, and dispose the light emitting surface 20a of the optical waveguide portion 20 in the concave portion 21, whereby the position of the light emitting surface 20a where light diffraction occurs. Py is set lower than the position Px of the reference surface S so that the diffracted light spreads at a deeper position in the silicon substrate 1.
　これにより、垂直転送チャネル３側に回り込む光のうち境界線Ｂ１，Ｂ２の下側を通過する光の量が、従来の固体撮像装置９０よりも多くなり、よって、境界線Ｂ１およびＢ２の内側の各領域に入射する光の量が少なくなる。その結果として、上記のノイズ電荷を低減することができるのである。 As a result, the amount of light that passes through the lower side of the boundary lines B1 and B2 out of the light that circulates toward the vertical transfer channel 3 side becomes larger than that of the conventional solid-state imaging device 90, and therefore, the inner side of the boundaries B1 and B2 The amount of light incident on each region is reduced. As a result, the noise charge can be reduced.
　以上のように、光の回折が生じる光出射面の位置とノイズ電荷の低減とが関係している。 As described above, the position of the light exit surface where light diffraction occurs and the reduction of noise charge are related.
　また、本発明者らによると、本実施形態におけるノイズ電荷の低減効果が、５ｄＢ程度あることが確認されている。 Further, according to the present inventors, it has been confirmed that the noise charge reducing effect in this embodiment is about 5 dB.
　本実施形態では、光導波路部２０のコア部７ａが、屈折率２．０の窒化シリコンからなるので、コア部７ａを通過する光の波長が、空気中と比べて１／２に小さくなるので、その分、回折の影響を抑制することができる。 In the present embodiment, since the core portion 7a of the optical waveguide portion 20 is made of silicon nitride having a refractive index of 2.0, the wavelength of light passing through the core portion 7a is halved compared to the air. Accordingly, the influence of diffraction can be suppressed.
　５．製造方法
　次に、本実施の形態に係る固体撮像装置１０の製造方法の一例について、図４および図５を用い説明する。 5. Manufacturing Method Next, an example of a manufacturing method of the solid-state imaging device 10 according to the present embodiment will be described with reference to FIGS.
　図４および図５は、固体撮像装置１０の製造方法を説明するための模式断面図である。なお、図４および図５には、各工程での中間生成物の端面が示されている。 4 and 5 are schematic cross-sectional views for explaining a method for manufacturing the solid-state imaging device 10. 4 and 5 show the end face of the intermediate product in each step.
　（ｉ）第１の工程
　先ず、シリコン基板１内に、ｎ型領域１ａ、ｐ型ウェル領域１ｂ、フォトダイオード２および垂直転送チャネル３を形成し、その後、シリコン基板１上の全体に酸化形成膜を積層し、積層した酸化形成膜の表面を熱酸化してシリコン酸化膜３０を形成する（図４（ａ））。 (I) First Step First, an n-type region 1a, a p-type well region 1b, a photodiode 2 and a vertical transfer channel 3 are formed in a silicon substrate 1, and then an oxide film is formed on the entire silicon substrate 1. And the silicon oxide film 30 is formed by thermally oxidizing the surface of the stacked oxide film (FIG. 4A).
　（ｉｉ）凹部形成工程
　次に、凹部２１の形成領域に対応して開口させたシリコン窒化膜からなるレジストパターン３１を用いて、ドライエッチングにより、シリコン基板１の上面に凹部２１の深さｄ１よりも浅い深さｄ２の凹部３２を形成する（図４（ｂ））。ここでの凹部３２の深さは、光導波路部２０の光出射面２０ａの基準面Ｓからの深さｄ２と同じ１００［ｎｍ］である。 (Ii) Recess Forming Step Next, by using the resist pattern 31 made of a silicon nitride film opened corresponding to the formation region of the recess 21, dry etching is performed on the upper surface of the silicon substrate 1 from the depth d 1 of the recess 21. A recess 32 having a shallow depth d2 is formed (FIG. 4B). Here, the depth of the concave portion 32 is 100 [nm], which is the same as the depth d2 of the light emitting surface 20a of the optical waveguide portion 20 from the reference surface S.
　形成した凹部３２の底部分を熱酸化し、凹部２１の形成領域全体を熱酸化膜３３で埋める（図４（ｃ））。ここでの熱酸化は、凹部２１の深さ（本例では２２０［ｎｍ］）に到達するまで行うので、凹部３２の底から１２０［ｎｍ］の深さまで熱酸化が必要である。 The bottom portion of the formed recess 32 is thermally oxidized, and the entire formation region of the recess 21 is filled with a thermal oxide film 33 (FIG. 4C). The thermal oxidation here is performed until the depth of the recess 21 (220 [nm] in this example) is reached, and therefore, thermal oxidation is required from the bottom of the recess 32 to a depth of 120 [nm].
　このように先ず、凹部２１の深さｄ１よりも浅い深さｄ２の凹部３２を形成し、形成した凹部３２の底部分を熱酸化することにより、平坦面に開口を持つレジストパターンで熱酸化するよりもバーズビークの発生を抑制できる。具体的に説明すると、平坦面に開口を持つレジストパターンで熱酸化を行うと、レジストパターンの開口端部が直接シリコン基板に接しているため、横方向の熱酸化によりバーズビーク形状の酸化膜が形成されるが、本発明は、露出された凹部３２の底面と側面に対して熱酸化を行うため、レジストパターン３１の開口部の端部は直接シリコン基板１に接することもなく、さらに、平坦面ではないため、バーズビークのような形状にはならない。また、レジストパターン３１を２００ｎｍ程度に厚く堆積してバーズビークを抑制することもでき、さらに、凹部３２を形成した後に酸化膜ウェットエッチ処理をして、レジストパターン３１下の酸化膜を２０ｎｍ程度後退させてから熱酸化することにより、バーズビークを小さくすることも可能である。 Thus, first, the recess 32 having a depth d2 shallower than the depth d1 of the recess 21 is formed, and the bottom portion of the formed recess 32 is thermally oxidized, thereby thermally oxidizing with a resist pattern having an opening on a flat surface. Can suppress the occurrence of bird's beak. Specifically, when thermal oxidation is performed with a resist pattern having an opening on a flat surface, the opening end of the resist pattern is in direct contact with the silicon substrate, so that a bird's beak-shaped oxide film is formed by lateral thermal oxidation. However, in the present invention, since the exposed bottom surface and side surface of the recessed portion 32 are thermally oxidized, the end portion of the opening portion of the resist pattern 31 does not directly contact the silicon substrate 1 and is further flat. Because it is not, it does not have a shape like a bird's beak. Further, the resist pattern 31 can be deposited to a thickness of about 200 nm to suppress bird's beaks. Further, after forming the recess 32, an oxide film wet etching process is performed to recede the oxide film under the resist pattern 31 by about 20 nm. It is also possible to reduce the bird's beak by performing thermal oxidation afterwards.
　熱酸化膜３３をフッ酸によって除去し、続いて、レジストパターン３１をリン酸ボイルにて除去する（図４（ｄ））。この結果、深さｄ１（２２０［ｎｍ］）の凹部２１が出来上がる。 The thermal oxide film 33 is removed with hydrofluoric acid, and then the resist pattern 31 is removed with phosphoric acid boil (FIG. 4D). As a result, a recess 21 having a depth d1 (220 [nm]) is completed.
　（ｉｉｉ）第１絶縁膜、ｐ+層の形成工程
　凹部２１およびシリコン酸化膜３０上に、ＣＶＤ法によりシリコン酸化膜を堆積させて、薄膜部分１４ａ１と厚膜部分１４ａ２とからなる第１絶縁膜１４ａを形成し、さらに、シリコン基板１内のｐ+層１２の形成領域に対応するレジストパターンを用いて、ボロン（Ｂ）をイオン注入することによりｐ+層１２を形成する（図４（ｅ））。 (Iii) Step of forming first insulating film and p + layer A first insulating film comprising a thin film portion 14a1 and a thick film portion 14a2 by depositing a silicon oxide film on the recess 21 and the silicon oxide film 30 by a CVD method. 14a is formed, and boron (B) is ion-implanted using a resist pattern corresponding to the formation region of the p + layer 12 in the silicon substrate 1 to form the p + layer 12 (FIG. 4E). )).
　（ｉｖ）転送電極形成工程
　第１絶縁膜１４ａ上の垂直転送チャネル３に相当する領域に、ＣＶＤ法およびフォトリソグラフィー法を用いて、多結晶シリコン膜からなる垂直転送電極４を形成する（図４（ｅ））。 (Iv) Transfer Electrode Formation Step A vertical transfer electrode 4 made of a polycrystalline silicon film is formed in a region corresponding to the vertical transfer channel 3 on the first insulating film 14a by using a CVD method and a photolithography method (FIG. 4). (E)).
　（ｖ）反射防止膜、第２絶縁膜の形成工程
　第１絶縁膜１４ａ上のフォトダイオード２に相当する領域に、ＣＶＤ法およびフォトリソグラフィー法を用いて、シリコン窒化膜からなる反射防止膜１３を形成する（図４（ｅ））。 (V) Step of forming antireflection film and second insulating film An antireflection film 13 made of a silicon nitride film is formed on a region corresponding to the photodiode 2 on the first insulating film 14a by using a CVD method and a photolithography method. It forms (FIG.4 (e)).
　その後、第１絶縁膜１４ａ上に形成された垂直転送電極４および反射防止膜１３上に、ＣＶＤ法によりシリコン酸化膜を堆積させて、第２絶縁膜１４ｂを形成する（図５（ａ））。 Thereafter, a silicon oxide film is deposited on the vertical transfer electrode 4 and the antireflection film 13 formed on the first insulating film 14a by a CVD method to form a second insulating film 14b (FIG. 5A). .
　（ｖｉ）第２の工程
　第２絶縁膜１４ｂ上に、ＣＶＤ法により金属膜を堆積形成し、フォトリソグラフィー法を用いて遮光膜５を形成する（図５（ａ））。 (Vi) Second Step A metal film is deposited and formed on the second insulating film 14b by the CVD method, and the light shielding film 5 is formed by using the photolithography method (FIG. 5A).
　（ｖｉｉ）第３の工程
　第２絶縁膜１４ｂ上に形成された遮光膜５上に、ＣＶＤ法により酸化シリコンを堆積させて、低屈折率層６を形成する（図５（ｂ））。このとき、遮光膜５の開口部５ａの内部において、遮光膜５の筒状部分５ｃの内周面に沿った筒状のクラッド部６ａが形成され、かつ筒状のクラッド部６ａの下端がシリコン基板１の凹部２１内に配置される。 (Vii) Third Step On the light shielding film 5 formed on the second insulating film 14b, silicon oxide is deposited by the CVD method to form the low refractive index layer 6 (FIG. 5B). At this time, a cylindrical cladding portion 6a along the inner peripheral surface of the cylindrical portion 5c of the light shielding film 5 is formed inside the opening 5a of the light shielding film 5, and the lower end of the cylindrical cladding portion 6a is silicon. It is disposed in the recess 21 of the substrate 1.
　次に、低屈折率層６上に、ＣＶＤ法により窒化シリコンを堆積させ、かつ低屈折率層６のクラッド部６ａの筒内を完全に埋め尽くすまで窒化シリコンを堆積させる。この後、堆積させた窒化シリコンの上面を、ＣＭＰ法により平坦化することにより、高屈折率層７を形成する（図５（ｃ））。このとき、遮光膜５の開口部５ａの内部において、低屈折率層６のクラッド部６ａの筒内に埋め込まれてなるコア部７ａが形成される。 Next, silicon nitride is deposited on the low refractive index layer 6 by the CVD method, and silicon nitride is deposited until the cylinder of the cladding portion 6a of the low refractive index layer 6 is completely filled. Thereafter, the high refractive index layer 7 is formed by planarizing the upper surface of the deposited silicon nitride by the CMP method (FIG. 5C). At this time, a core portion 7 a is formed in the opening 5 a of the light shielding film 5 and embedded in the cylinder of the cladding portion 6 a of the low refractive index layer 6.
　このようにして低屈折率層６および高屈折率層７を形成することにより、クラッド部６ａおよびコア部７ａにより構成される光導波路部２０が出来上がる。 By forming the low refractive index layer 6 and the high refractive index layer 7 in this manner, the optical waveguide portion 20 composed of the cladding portion 6a and the core portion 7a is completed.
　こうして、遮光膜５の開口部５ａの内部からシリコン基板１の凹部２１内に至る光導波路部２０が形成され、よって、光導波路部２０の光出射面２０ａの位置Ｐｙが、シリコン基板１の基準面Ｓの位置Ｐｘよりも低くなる。 Thus, the optical waveguide portion 20 extending from the inside of the opening portion 5a of the light shielding film 5 to the concave portion 21 of the silicon substrate 1 is formed, so that the position Py of the light emitting surface 20a of the optical waveguide portion 20 is the reference of the silicon substrate 1. It becomes lower than the position Px of the surface S.
　（ｖｉｉｉ）カラーフィルタ層、平坦化層およびマイクロレンズの形成工程
　最後に、カラーフィルタ層８、平坦化層９およびマイクロレンズ１１を形成する（図５（ｃ））。 (Viii) Color Filter Layer, Flattening Layer, and Microlens Formation Process Finally, the color filter layer 8, the flattening layer 9, and the microlens 11 are formed (FIG. 5C).
　以上の工程を経て、固体撮像装置１０が製造される。 The solid-state imaging device 10 is manufactured through the above steps.
　本実施の形態では、上記凹部形成工程において、凹部２１内周面にシリコンの結晶欠陥が発生するが、シリコン基板１内に凹部２１内周面に沿うＰ＋層１２を形成することにより、凹部２１内周面におけるシリコンの結晶欠陥による電荷が発生したとしても、発生した電荷がフォトダイオード２の信号電荷に混ざるのを防止することができる。 In the present embodiment, in the recess forming step, silicon crystal defects are generated on the inner peripheral surface of the recess 21, but by forming the P + layer 12 along the inner peripheral surface of the recess 21 in the silicon substrate 1, the recess 21 is formed. Even if charges are generated due to silicon crystal defects on the inner peripheral surface, the generated charges can be prevented from being mixed with the signal charges of the photodiode 2.
　［実施の形態２］
　１．構成
　次に、本発明の実施の形態２に係る固体撮像装置４０の構成について、図６を用いて説明する。図６は、固体撮像装置４０の要部を示す模式断面図である。 [Embodiment 2]
1. Configuration Next, the configuration of the solid-state imaging device 40 according to Embodiment 2 of the present invention will be described with reference to FIG. FIG. 6 is a schematic cross-sectional view showing the main part of the solid-state imaging device 40.
　上記実施の形態１に係る固体撮像装置１０では、遮光膜５の筒状部分５ｃの下端が、シリコン基板１の基準面Ｓの位置Ｐｘよりも高い位置にあるので、光導波路部２０の一部は、遮光膜５の筒状部分５ｃに囲まれていない。 In the solid-state imaging device 10 according to the first embodiment, since the lower end of the cylindrical portion 5c of the light shielding film 5 is located higher than the position Px of the reference plane S of the silicon substrate 1, a part of the optical waveguide portion 20 Is not surrounded by the cylindrical portion 5 c of the light shielding film 5.
　これに対して、本実施の形態２に係る固体撮像装置４０では、遮光膜４５の筒状部分４５ｃが、シリコン基板１の凹部２１内に至るまで延設されてなり、筒状部分４５ｃの下端の位置Ｐｚがシリコン基板１の基準面Ｓの位置Ｐｘよりも低く、光導波路部４９の全体が、遮光膜４５の筒状部分４５ｃに囲まれている点で相違する。なお、図２に示す固体撮像装置１０と同じ構成要素については、簡単のため、同じ符号で示し、その説明を省略する。 On the other hand, in the solid-state imaging device 40 according to the second embodiment, the cylindrical portion 45c of the light shielding film 45 extends to the inside of the recess 21 of the silicon substrate 1, and the lower end of the cylindrical portion 45c. The position Pz is lower than the position Px of the reference plane S of the silicon substrate 1, and the optical waveguide portion 49 is entirely surrounded by the cylindrical portion 45 c of the light shielding film 45. The same components as those of the solid-state imaging device 10 shown in FIG. 2 are denoted by the same reference numerals for the sake of simplicity, and the description thereof is omitted.
　２．作用効果
　本実施の形態に係る固体撮像装置４０が有する作用効果を説明する前に、光導波路部の屈折率の異なるコア部とクラッド部との界面における、光の全反射の前提について説明する。 2. Operational Effects Before describing the operational effects of the solid-state imaging device 40 according to the present embodiment, the premise of total reflection of light at the interface between the core portion and the cladding portion having different refractive indexes of the optical waveguide portion will be described.
　上記実施の形態１では、屈折率の異なるコア部７ａとクラッド部６ａとの界面において、光を全反射させることができると説明したが、その前提として、界面に対する光の入射角がある一定の角度θ以上必要である。ここでの角度θは、コア部の屈折率ｎ１およびクラッド部の屈折率ｎ２から求めることができる（Ｓｉｎθ＝ｎ２／ｎ１）。 In the first embodiment, it has been described that light can be totally reflected at the interface between the core portion 7a and the cladding portion 6a having different refractive indexes. However, as a premise, the incident angle of light with respect to the interface is constant. An angle θ or more is necessary. Here, the angle θ can be obtained from the refractive index n1 of the core portion and the refractive index n2 of the cladding portion (Sinθ = n2 / n1).
　したがって、上記実施の形態１では、コア部７ａの屈折率が２．０、クラッド部６ａが１．４５であるので、界面で全反射させるには光の入射角θが４６．５［°]以上必要であり、入射角θが４６．５［°］未満の場合には界面を通過する光が生じることになる。 Therefore, in the first embodiment, since the refractive index of the core portion 7a is 2.0 and the cladding portion 6a is 1.45, the incident angle θ of light is 46.5 [°] for total reflection at the interface. As described above, when the incident angle θ is less than 46.5 [°], light passing through the interface is generated.
　そのため、上記実施の形態１に係る固体撮像装置１０では、光導波路部２０に上方からの光が斜めに入射した場合など、光導波路部２０の遮光膜５の筒状部分５ｃに囲まれていない部分のコア部７ａとクラッド部６ａとの界面に、入射角θが４６．５［°］未満の角度の光が入射するときには、界面を通過する光が生じて光導波路部の外周から光が漏れるおそれがある。こうして漏れた光が転送チャネル付近に入射した場合には、光により発生した電荷が転送チャネル内の信号電荷に混ざり込むノイズ電荷となって、画質が劣化するという問題になる。 Therefore, in the solid-state imaging device 10 according to the first embodiment, the light is not surrounded by the cylindrical portion 5c of the light shielding film 5 of the optical waveguide unit 20 such as when light from above enters the optical waveguide unit 20 obliquely. When light having an incident angle θ of less than 46.5 [°] is incident on the interface between the core portion 7a and the cladding portion 6a, light passing through the interface is generated and light is transmitted from the outer periphery of the optical waveguide portion. There is a risk of leakage. When the leaked light enters the vicinity of the transfer channel, the charge generated by the light becomes a noise charge mixed with the signal charge in the transfer channel, which causes a problem that the image quality deteriorates.
　これに対して、上記構成を有する本実施の形態２に係る固体撮像装置４０では、遮光膜４５の筒状部分４５ｃが、シリコン基板１の凹部２１内に至るまで延設されているので、光導波路部４９の外周全体が遮光膜４５の筒状部分４５ｃに囲まれている。これにより、コア部４７ａとクラッド部４６ａとの界面に入射角θ４６．５［°］未満の角度の光が入射した場合に、界面を通過する光が生じたとしても、界面を通過した光は、遮光膜４５の筒状部分４５ｃによって反射されるので、光導波路部４９の外周から光が漏れるのを防止することができる。 On the other hand, in the solid-state imaging device 40 according to the second embodiment having the above-described configuration, the cylindrical portion 45c of the light shielding film 45 is extended to reach into the recess 21 of the silicon substrate 1, so that the light guide The entire outer periphery of the waveguide portion 49 is surrounded by the cylindrical portion 45 c of the light shielding film 45. Accordingly, even when light having an incident angle of less than θ46.5 [°] is incident on the interface between the core portion 47a and the cladding portion 46a, the light that has passed through the interface is Since the light is reflected by the cylindrical portion 45 c of the light shielding film 45, it is possible to prevent light from leaking from the outer periphery of the optical waveguide portion 49.
　以上より、固体撮像装置４０は、第１の実施形態の固体撮像装置１０と比べて、光導波路部４９の外周から光が漏れるのを防止することにより、画質が劣化するのをより抑制することができるとともに、フォトダイオード２への集光効率をより高めることができる。 As described above, the solid-state imaging device 40 further suppresses deterioration in image quality by preventing light from leaking from the outer periphery of the optical waveguide portion 49, as compared with the solid-state imaging device 10 of the first embodiment. In addition, the light collection efficiency to the photodiode 2 can be further increased.
　［実施の形態３］
　１．構成
　次に、本発明の実施の形態３に係る固体撮像装置５０の構成について、図７を用いて説明する。図７は、固体撮像装置５０の要部を示す模式断面図である。 [Embodiment 3]
1. Configuration Next, the configuration of the solid-state imaging device 50 according to Embodiment 3 of the present invention will be described with reference to FIG. FIG. 7 is a schematic cross-sectional view showing the main part of the solid-state imaging device 50.
　上記実施の形態１に係る固体撮像装置１０では、高屈折率層７上に、カラーフィルタ層８が設けられているのに対して、図７に示すように、本実施の形態２に係る固体撮像装置５０では、高屈折率層５７がカラーフィルタとしての機能を有し、別途カラーフィルタ層が設けられていない点で相違する。なお、図２に示す固体撮像装置１０と同じ構成要素については、簡単のため、同じ符号で示し、その説明を省略する。 In the solid-state imaging device 10 according to Embodiment 1 described above, the color filter layer 8 is provided on the high refractive index layer 7, whereas as shown in FIG. 7, the solid-state imaging device 10 according to Embodiment 2 The imaging device 50 is different in that the high refractive index layer 57 has a function as a color filter and no separate color filter layer is provided. The same components as those of the solid-state imaging device 10 shown in FIG. 2 are denoted by the same reference numerals for the sake of simplicity, and the description thereof is omitted.
　高屈折率層５７は、低屈折率層６を構成する酸化シリコン（屈折率１．４５）よりも屈折率の高いカラーフィルタ材料、例えば、顔料が分散された有機材料（屈折率１．７）で構成されている。 The high refractive index layer 57 is a color filter material having a refractive index higher than that of silicon oxide (refractive index 1.45) constituting the low refractive index layer 6, for example, an organic material (refractive index 1.7) in which pigments are dispersed. It consists of
　光導波路部５９は、低屈折率層６のクラッド部６ａおよび高屈折率層５７のコア部５７ａにより構成されている。 The optical waveguide portion 59 includes a cladding portion 6 a of the low refractive index layer 6 and a core portion 57 a of the high refractive index layer 57.
　２．作用効果
　上記構成を有する本実施の形態３に係る固体撮像装置５０では、高屈折率層５７がカラーフィルタとしての機能を有するので、別途カラーフィルタ層を設ける必要がなく、上記実施の形態１に係る固体撮像装置１０と比べて、カラーフィルタ層の厚み分、マイクロレンズ５１をシリコン基板１のフォトダイオード２に近づけることができる。これにより、固体撮像装置５０は、第１の実施形態の固体撮像装置１０と比べて、レンズの開口数（ＮＡ）を向上させることができ、かつ集光効率をより向上させることができる。 2. In the solid-state imaging device 50 according to the third embodiment having the above-described configuration, since the high refractive index layer 57 has a function as a color filter, it is not necessary to provide a separate color filter layer, and the first embodiment described above is used. Compared to the solid-state imaging device 10, the microlens 51 can be brought closer to the photodiode 2 of the silicon substrate 1 by the thickness of the color filter layer. Thereby, the solid-state imaging device 50 can improve the numerical aperture (NA) of the lens and the light collection efficiency more than the solid-state imaging device 10 of the first embodiment.
　なお、マイクロレンズ５１の曲率半径は、マイクロレンズ５１がフォトダイオード２に近づき、レンズの集光距離が短くなるのに対応して、第１の実施形態のマイクロレンズ１１の曲率半径よりも小さく設定されている。 The radius of curvature of the microlens 51 is set to be smaller than the radius of curvature of the microlens 11 of the first embodiment, corresponding to the fact that the microlens 51 approaches the photodiode 2 and the condensing distance of the lens is shortened. Has been.
　本実施の形態３に係る固体撮像装置５０では、製造工程において、カラーフィルタ層の工程が不要になる分、作業負荷およびコストを削減することができる。 In the solid-state imaging device 50 according to the third embodiment, the work load and the cost can be reduced because the process of the color filter layer is not necessary in the manufacturing process.
　［実施の形態４］
　１．構成
　次に、本発明の実施の形態４に係る固体撮像装置６０の構成について、図８を用いて説明する。図８は、固体撮像装置６０の要部を示す模式断面図である。 [Embodiment 4]
1. Configuration Next, the configuration of the solid-state imaging device 60 according to Embodiment 4 of the present invention will be described with reference to FIG. FIG. 8 is a schematic cross-sectional view showing the main part of the solid-state imaging device 60.
　上記実施の形態１に係る固体撮像装置１０では、高屈折率層７は、層内レンズを構成していないのに対して、図８に示すように、本実施の形態４に係る固体撮像装置６０では、高屈折率層６７の上面が上方に向けて凸面状に形成され、かつ高屈折率層６７のコア部６７ａの外周面が下方に向けて凸面状に形成されており、これにより、高屈折率層６７が層内レンズを構成している点で相違する。なお、図２に示す固体撮像装置１０と同じ構成要素については、簡単のため、同じ符号で示し、その説明を省略する。 In the solid-state imaging device 10 according to the first embodiment, the high refractive index layer 7 does not constitute an in-layer lens, whereas as shown in FIG. 8, the solid-state imaging device according to the fourth embodiment. 60, the upper surface of the high refractive index layer 67 is formed in a convex shape upward, and the outer peripheral surface of the core portion 67a of the high refractive index layer 67 is formed in a convex shape downward. The difference is that the high refractive index layer 67 constitutes an in-layer lens. The same components as those of the solid-state imaging device 10 shown in FIG. 2 are denoted by the same reference numerals for the sake of simplicity, and the description thereof is omitted.
　低屈折率層６６では、筒状のクラッド部６６ａの内径が、クラッド部６６ａの上端から下端に向かうにつれて漸次縮小され、クラッド部６６ａの内周面６６ａ１が凹面状に形成されている。この低屈折率層６６は、リフロー材料、例えばＢＰＳＧ（Ｂｏｒｏｎ　Ｐｈｏｓｐｈｏｒｕｓ　Ｓｉｌｉｃｏｎ　Ｇｌａｓｓ）（屈折率１．４５）からなり、加熱処理により成形されている。 In the low refractive index layer 66, the inner diameter of the cylindrical clad portion 66a is gradually reduced from the upper end to the lower end of the clad portion 66a, and the inner peripheral surface 66a1 of the clad portion 66a is formed in a concave shape. The low refractive index layer 66 is made of a reflow material, for example, BPSG (Boron Phosphorus Silicon Glass) (refractive index 1.45), and is formed by heat treatment.
　高屈折率層６７では、コア部６７ａの外周面６７ａ１が、クラッド部６６ａの内周面６６ａ１に沿う凸面状である。 In the high refractive index layer 67, the outer peripheral surface 67a1 of the core portion 67a has a convex shape along the inner peripheral surface 66a1 of the cladding portion 66a.
　高屈折率層６７の上面には、コア部６７ａの上方の領域に、凸部６７ｂが設けられている。 On the upper surface of the high refractive index layer 67, a convex portion 67b is provided in a region above the core portion 67a.
　これらコア部６７ａが下向きの凸レンズをなし、凸部６７ｂが上向きの凸レンズをなし、よって、高屈折率層６７が層内レンズとして機能する。高屈折率層６７は、例えばシリコン窒化膜（屈折率１．９）からなる。 The core portion 67a forms a downward convex lens, and the convex portion 67b forms an upward convex lens. Therefore, the high refractive index layer 67 functions as an in-layer lens. The high refractive index layer 67 is made of, for example, a silicon nitride film (refractive index 1.9).
　このようなクラッド部６６ａおよびコア部６７ａにより、光導波路部６９が構成されている。また、光導波路部６９の光出射面６９ａは、コア部６７ａの外周面６７ａ１の一部分であって、コア部６７ａの下端を含む略平面状の部分（図８の太線で示す部分）で構成されている。この光出射面６９ａを構成する略平面状の部分は、コア部６７ａの外周面６７ａ１において、入射光をほとんど反射させずに透過させることができる部分である。本実施形態においても、光出射面６９ａの位置Ｐｙは、シリコン基板１の基準面Ｓよりも低くされている。 The optical waveguide portion 69 is constituted by the clad portion 66a and the core portion 67a. Further, the light exit surface 69a of the optical waveguide portion 69 is a part of the outer peripheral surface 67a1 of the core portion 67a, and is constituted by a substantially planar portion (a portion indicated by a thick line in FIG. 8) including the lower end of the core portion 67a. ing. The substantially planar portion constituting the light emitting surface 69a is a portion that can transmit incident light on the outer peripheral surface 67a1 of the core portion 67a with almost no reflection. Also in the present embodiment, the position Py of the light emitting surface 69a is set lower than the reference surface S of the silicon substrate 1.
　高屈折率層６７上に、上面を平坦化するための平坦化層６８が形成され、平坦化層６８上にカラーフィルタ層８が形成されている。 A flattening layer 68 for flattening the upper surface is formed on the high refractive index layer 67, and the color filter layer 8 is formed on the flattening layer 68.
　２．作用効果
　上記構成を有する本実施の形態４に係る固体撮像装置６０では、高屈折率層６７が層内レンズとして構成されているので、フォトダイオード２への集光効率をより向上させることができる。 2. In the solid-state imaging device 60 according to the fourth embodiment having the above-described configuration, since the high refractive index layer 67 is configured as an inner lens, the light collection efficiency to the photodiode 2 can be further improved. .
　なお、本実施の形態４において、略平面状の光出射面６９ａの構成を示したが、これに限定するものではなく、例えば、光出射面が湾曲した形状からなる構成とすることもできる。光出射面全体が、シリコン基板１の基準面Ｓよりも低く設定されている限り、従来よりも回折光による画質の劣化を抑制することができる。 In the fourth embodiment, the configuration of the substantially planar light emitting surface 69a is shown. However, the present invention is not limited to this. For example, the light emitting surface may have a curved shape. As long as the entire light emitting surface is set lower than the reference surface S of the silicon substrate 1, it is possible to suppress deterioration in image quality due to diffracted light as compared with the conventional case.
　［実施の形態５］
　１．製造方法
　次に、本発明の実施の形態５に係る固体撮像装置の製造方法について、図９および図１０を用いて説明する。 [Embodiment 5]
1. Manufacturing Method Next, a manufacturing method of the solid-state imaging device according to the fifth embodiment of the present invention will be described with reference to FIGS.
　上記実施の形態１に係る固体撮像装置１０の製造方法では、転送電極形成工程および遮光膜５を形成する第２の工程の前に、凹部形成工程を行うのに対して、本実施形態の製造方法では、第２の工程の後に凹部形成工程を行う点で相違する。なお、図４および図５に示す固体撮像装置１０の製造方法と同じ工程については、その説明を省略するか簡略するにとどめる。 In the manufacturing method of the solid-state imaging device 10 according to the first embodiment, the recess forming step is performed before the transfer electrode forming step and the second step of forming the light shielding film 5, whereas the manufacturing of the present embodiment is performed. The method is different in that a recess forming step is performed after the second step. Note that the description of the same steps as those of the method of manufacturing the solid-state imaging device 10 shown in FIGS. 4 and 5 is omitted or simplified.
　（ｉ）第１の工程、第１絶縁膜の形成工程
　先ず、シリコン基板１内に、フォトダイオード２、垂直転送チャネル３などを形成し、その後、シリコン基板１上全体に酸化形成膜を積層し、積層した酸化形成膜の表面を熱酸化して第１絶縁膜６４ａを形成する（図９（ａ））。 (I) First Step, First Insulating Film Forming Step First, a photodiode 2, a vertical transfer channel 3, etc. are formed in a silicon substrate 1, and then an oxide forming film is laminated on the entire silicon substrate 1. Then, the surface of the stacked oxide film is thermally oxidized to form the first insulating film 64a (FIG. 9A).
　（ｉｉ）転送電極、第２絶縁膜の形成工程》
　次に、第１絶縁膜６４ａ上に垂直転送電極４を形成し、第１絶縁膜６４ａ上に形成された垂直転送電極４上に第２絶縁膜６４ｂを形成する（図９（ｂ））。 (Ii) Step of forming transfer electrode and second insulating film >>
Next, the vertical transfer electrode 4 is formed on the first insulating film 64a, and the second insulating film 64b is formed on the vertical transfer electrode 4 formed on the first insulating film 64a (FIG. 9B).
　（ｉｉｉ）第２の工程
　次に、第２絶縁膜６４ｂ上に遮光膜５を形成する（図９（ｂ））。 (Iii) Second Step Next, the light shielding film 5 is formed on the second insulating film 64b (FIG. 9B).
　（ｉｖ）凹部形成工程
　次に、レジストパターン６１を用いてドライエッチングにより凹部６２を形成し（図９（ｃ））、熱酸化により凹部６２の形成領域全体を熱酸化膜６３で埋め（図９（ｄ））、その後、酸化膜６３およびレジストパターン６１を除去する（図１０（ａ））。この結果、凹部２１が出来上がる。 (Iv) Recess Formation Step Next, the recess 62 is formed by dry etching using the resist pattern 61 (FIG. 9C), and the entire formation region of the recess 62 is filled with the thermal oxide film 63 by thermal oxidation (FIG. 9). (D)) After that, the oxide film 63 and the resist pattern 61 are removed (FIG. 10A). As a result, the recess 21 is completed.
　（ｖ）第３の工程、ｐ+層の形成工程
　次に、遮光膜５上に低屈折率層６を形成し、さらに、イオン注入により、シリコン基板１内に凹部２１内周面に沿うｐ+層１２を形成する（図１０（ｂ））。その後、低屈折率層６上に高屈折率層７を形成する（図１０（ｃ））。こうして、クラッド部６ａおよびコア部７ａにより構成される光導波路部２０が出来上がる。 (V) Third Step, Step of Forming p + Layer Next, the low refractive index layer 6 is formed on the light shielding film 5, and further, p is formed along the inner peripheral surface of the recess 21 in the silicon substrate 1 by ion implantation. A + layer 12 is formed (FIG. 10B). Thereafter, the high refractive index layer 7 is formed on the low refractive index layer 6 (FIG. 10C). In this way, the optical waveguide part 20 comprised by the clad part 6a and the core part 7a is completed.
　ここでの低屈折率層６は、凹部２１内では、凹部２１内周面に沿って形成されている。これは、本実施形態では、凹部形成工程の前に、第１および第２絶縁膜６４ａ，６４ｂが形成されていて、凹部形成工程におけるドライエッチングにより第１および第２絶縁膜６４ａ，６４ｂにおける凹部２１内の部分が一緒に除去されていて、凹部２１内には第１および第２絶縁膜６４ａ，６４ｂがないからである。 Here, the low refractive index layer 6 is formed in the recess 21 along the inner peripheral surface of the recess 21. In this embodiment, the first and second insulating films 64a and 64b are formed before the recess forming step, and the recesses in the first and second insulating films 64a and 64b are formed by dry etching in the recess forming step. This is because the portions in 21 are removed together, and there are no first and second insulating films 64a and 64b in the recess 21.
　以降の工程は、上記実施の形態１に係る固体撮像装置１０の製造方法と同じである。 The subsequent steps are the same as the manufacturing method of the solid-state imaging device 10 according to the first embodiment.
　２．作用効果
　本実施の形態に係る固体撮像装置の製造方法では、凹部２１を形成する前に垂直転送電極４および遮光膜５を形成するので、凹部２１形成後に垂直転送電極４および遮光膜５を形成するのと比べて、シリコン基板１の上面１ｃに凹凸がない分、垂直転送電極４および遮光膜５の形成が容易に行えるという利点がある。 2. In the method for manufacturing the solid-state imaging device according to the present embodiment, the vertical transfer electrode 4 and the light shielding film 5 are formed before the recess 21 is formed. Therefore, the vertical transfer electrode 4 and the light shielding film 5 are formed after the recess 21 is formed. Compared with this, there is an advantage that the vertical transfer electrode 4 and the light shielding film 5 can be easily formed because the upper surface 1c of the silicon substrate 1 is not uneven.
　なお、本実施の形態に係る固体撮像装置の製造方法では、シリコン基板１の凹部２１内に、第１および第２絶縁膜と、反射防止膜とを形成する工程を含まない構成を示したが、凹部形成工程の後、形成した凹部２１内に、第１および第２絶縁膜や反射防止膜を形成する工程を含む構成としてもよい。 In the method for manufacturing the solid-state imaging device according to the present embodiment, a configuration not including the step of forming the first and second insulating films and the antireflection film in the recess 21 of the silicon substrate 1 is shown. After the recess forming step, the first and second insulating films and the antireflection film may be formed in the formed recess 21.
　［実施の形態６］
　１．製造方法
　次に、本発明の実施の形態６に係る固体撮像装置の製造方法について、図１１および図１２を用いて説明する。 [Embodiment 6]
1. Manufacturing Method Next, a manufacturing method of the solid-state imaging device according to the sixth embodiment of the present invention will be described with reference to FIGS.
　上記実施の形態１に係る固体撮像装置１０の製造方法では、転送電極形成工程および遮光膜５を形成する第２の工程の前に、凹部形成工程を行うのに対して、本実施形態の製造方法では、転送電極形成工程と第２の工程との間に凹部形成工程を行う点で相違する。なお、図４および図５に示す固体撮像装置１０の製造方法と同じ工程については、その説明を省略するか簡略するにとどめる。 In the manufacturing method of the solid-state imaging device 10 according to the first embodiment, the recess forming step is performed before the transfer electrode forming step and the second step of forming the light shielding film 5, whereas the manufacturing of the present embodiment is performed. The method is different in that a recess forming step is performed between the transfer electrode forming step and the second step. Note that the description of the same steps as those of the method of manufacturing the solid-state imaging device 10 shown in FIGS. 4 and 5 is omitted or simplified.
　（ｉ）第１の工程、第１絶縁膜の形成工程
　先ず、シリコン基板１内に、フォトダイオード２、垂直転送チャネル３などを形成し、その後、シリコン基板１上全体に、第１絶縁膜７４ａを形成する（図１１（ａ））。 (I) First Step, First Insulating Film Forming Step First, the photodiode 2, the vertical transfer channel 3 and the like are formed in the silicon substrate 1, and then the first insulating film 74a is entirely formed on the silicon substrate 1. Is formed (FIG. 11A).
　（ｉｉ）転送電極形成工程
　次に、第１絶縁膜７４ａ上に、垂直転送電極４を形成する（図１１（ａ））。 (Ii) Transfer Electrode Formation Step Next, the vertical transfer electrode 4 is formed on the first insulating film 74a (FIG. 11A).
　（ｉｉｉ）凹部形成工程、第２絶縁膜の形成工程
　次に、窒化シリコンからなるレジストパターン７１を用いてドライエッチングにより深さｄ２の凹部７２を形成し（図１１（ｂ））、熱酸化により凹部２１の形成領域全体を熱酸化膜７３で埋め（図１１（ｃ））、その後、酸化膜７３を除去する（図１１（ｄ））。この結果、凹部２１が出来上がる。なお、本実施形態では、レジストパターン７１は除去せずに残しておく。 (Iii) Concave Forming Step, Second Insulating Film Forming Step Next, a concave portion 72 having a depth d2 is formed by dry etching using a resist pattern 71 made of silicon nitride (FIG. 11 (b)) and thermally oxidized. The entire formation region of the recess 21 is filled with the thermal oxide film 73 (FIG. 11C), and then the oxide film 73 is removed (FIG. 11D). As a result, the recess 21 is completed. In the present embodiment, the resist pattern 71 is left without being removed.
　そして、凹部２１内周面およびレジストパターン７１を熱酸化して、凹部２１内周面に沿った熱酸化膜７５（シリコン酸化膜）を形成するとともに、垂直転送電極４上の酸窒化シリコンからなる第２絶縁膜７４ｂを形成する（図１２（ａ））。 Then, the inner peripheral surface of the recess 21 and the resist pattern 71 are thermally oxidized to form a thermal oxide film 75 (silicon oxide film) along the inner peripheral surface of the recess 21 and made of silicon oxynitride on the vertical transfer electrode 4. A second insulating film 74b is formed (FIG. 12A).
　このように凹部２１内周面を熱酸化して熱酸化膜を形成している点と、第２絶縁膜に酸窒化シリコンからなる絶縁膜を用いている点とが、第１の実施形態と相違する。 The point that the thermal oxidation film is formed by thermally oxidizing the inner peripheral surface of the recess 21 in this way, and the point that the insulating film made of silicon oxynitride is used for the second insulating film are the same as in the first embodiment. Is different.
　（ｉｖ）ｐ+層の形成工程
　次に、イオン注入により、シリコン基板１内に凹部２１内周面に沿うＰ＋層１２を形成する（図１２（ａ））。 (Iv) Step of forming p + layer Next, a P + layer 12 is formed in the silicon substrate 1 along the inner peripheral surface of the recess 21 by ion implantation (FIG. 12A).
　（ｖ）第２の工程
　次に、第２絶縁膜７４ｂ上に遮光膜５を形成する（図１２（ａ））
　（ｖｉ）第３の工程
　次に、遮光膜５上および凹部２１内の熱酸化膜７５上に低屈折率層６を形成し（図１２（ｂ））、低屈折率層６上に高屈折率層７を形成する（図１２（ｃ））。これにより、クラッド部６ａおよびコア部７ａにより構成される光導波路部２０が出来上がる。 (V) Second Step Next, the light shielding film 5 is formed on the second insulating film 74b (FIG. 12A).
(Vi) Third Step Next, the low refractive index layer 6 is formed on the light shielding film 5 and the thermal oxide film 75 in the recess 21 (FIG. 12B), and the high refractive index is formed on the low refractive index layer 6. The rate layer 7 is formed (FIG. 12C). Thereby, the optical waveguide part 20 comprised by the clad part 6a and the core part 7a is completed.
　以降の工程は、第１の実施形態の製造方法と同じである。 The subsequent steps are the same as in the manufacturing method of the first embodiment.
　２．作用効果
　本実施の形態に係る固体撮像装置の製造方法では、凹部２１を形成する前に垂直転送電極４を形成するので、凹部２１形成後に垂直転送電極４を形成するのと比べて、シリコン基板１の上面１ｃに凹凸がない分、垂直転送電極４の形成が容易に行えるという利点がある。 2. In the manufacturing method of the solid-state imaging device according to the present embodiment, the vertical transfer electrode 4 is formed before the recess 21 is formed, and therefore, compared with the case where the vertical transfer electrode 4 is formed after the recess 21 is formed. There is an advantage that the vertical transfer electrode 4 can be easily formed because there is no unevenness on the upper surface 1c of the first electrode.
　また、本実施形態では、凹部形成工程の後、凹部２１内周面を熱酸化しており、これにより、凹部２１内周面に発生したシリコンの結晶欠陥の回復を図ることができる。 In the present embodiment, the inner peripheral surface of the concave portion 21 is thermally oxidized after the concave portion forming step, so that the silicon crystal defects generated on the inner peripheral surface of the concave portion 21 can be recovered.
　［変形例］
　例えば、以下のような変形例が考えられる。 [Modification]
For example, the following modifications can be considered.
　上記実施の形態１～４では、光電変換部がフォトダイオードからなる構成を示したが、光電変換部の構成を限定するものではない。 In the above first to fourth embodiments, the configuration in which the photoelectric conversion unit is made of a photodiode is shown, but the configuration of the photoelectric conversion unit is not limited.
　上記実施の形態１～４では、第１の屈折率の透明材料として酸化シリコンを用い、第２の屈折率の透明材料として窒化シリコンを用いた構成を示したが、第１の屈折率の透明材料よりも、第２の屈折率の透明材料の屈折率が高ければよく、これに限定するものではない。例えば、第１の屈折率の透明材料を酸化シリコンとし、第２の屈折率の透明材料として酸窒化シリコン（屈折率１．６～２）を用いてもよい。 In the first to fourth embodiments, silicon oxide is used as the transparent material having the first refractive index and silicon nitride is used as the transparent material having the second refractive index. The refractive index of the transparent material having the second refractive index is higher than that of the material, and the present invention is not limited to this. For example, the transparent material having the first refractive index may be silicon oxide, and the transparent material having the second refractive index may be silicon oxynitride (refractive index: 1.6 to 2).
　第１の実施形態において、凹部２１の深さｄ１を２２０［ｎｍ］程度、光導波路部２０の光出射面２０ａの深さｄ２を１００［ｎｍ］程度として説明したが、これに限定するものではない。光導波路部の光出射面の位置が、シリコン基板の基準面よりも低ければ低いほど、回折により転送チャネル付近に入射する光の量が少なくなってノイズ電荷の低減効果が高くなるが、その一方で、凹部をより深くすることにより、例えば、凹部内周面におけるシリコンの結晶欠陥が増加する、または、フォトダイオードが転送チャネルから離れるために信号電荷の読み出しに高い電圧が必要になるなどの影響がでる。よって、光出射面の深さおよび凹部の深さは、固体撮像装置の仕様によって適宜設定するのが好ましい。 In the first embodiment, the depth d1 of the recess 21 is about 220 [nm] and the depth d2 of the light emitting surface 20a of the optical waveguide section 20 is about 100 [nm]. However, the present invention is not limited to this. Absent. The lower the position of the light exit surface of the optical waveguide portion than the reference surface of the silicon substrate, the smaller the amount of light incident on the vicinity of the transfer channel due to diffraction and the higher the noise charge reduction effect. By making the recess deeper, for example, the silicon crystal defects on the inner peripheral surface of the recess increase, or a high voltage is required to read the signal charge because the photodiode is separated from the transfer channel. I get out. Therefore, it is preferable to appropriately set the depth of the light exit surface and the depth of the recess depending on the specifications of the solid-state imaging device.
　上記実施の形態１～４では、シリコン基板がｎ型領域とｐ型ウェル領域とからなり、ｐ型ウェル領域内にフォトダイオードおよび垂直転送チャネルが形成された構成を示したが、これに限定するものではない。 In the first to fourth embodiments, the silicon substrate includes the n-type region and the p-type well region, and the photodiode and the vertical transfer channel are formed in the p-type well region. However, the present invention is limited to this. It is not a thing.
　上記実施形態では、本発明に係る固体撮像装置の製造方法について説明したが、固体撮像装置の製造方法を特に限定するものではない。固体撮像装置の仕様または用途に合わせて、その製造方法を適宜選択することができる。 In the above embodiment, the manufacturing method of the solid-state imaging device according to the present invention has been described, but the manufacturing method of the solid-state imaging device is not particularly limited. The manufacturing method can be appropriately selected according to the specification or application of the solid-state imaging device.
　本発明は、高画質な固体撮像装置を実現するのに有用である。 The present invention is useful for realizing a high-quality solid-state imaging device.
　　１．シリコン基板
　　１ａ．ｎ型領域
　　１ｂ．ｐ型ウェル領域
　　１ｃ．上面
　　２．フォトダイオード
　　３ａ，３ｂ．垂直転送チャネル
　　４．垂直転送電極
　　５．遮光膜
　　５ａ．開口部
　　５ｂ．板状部分
　　５ｃ．筒状部分
　　６．低屈折率層
　　６ａ．クラッド部
　　７．高屈折率層
　　７ａ．コア部
　　８．カラーフィルタ層
　１０．固体撮像装置
　１１．マイクロレンズ
　１３．反射防止膜
　２０．光導波路部
　２０ａ．光出射面
　２０ｃ．下端
　２１．凹部
　４０，５０，６０．固体撮像装置
　６６ａ．クラッド部
　６６ａ１．内周面
　６７．高屈折率層
　６７ａ．コア部
　６７ａ１．外周面
　　Ｓ．基準面 1. Silicon substrate 1a. n-type region 1b. p-type well region 1c. Upper surface 2. Photodiode 3a, 3b. Vertical transfer channel 4. 4. Vertical transfer electrode Light shielding film 5a. Opening 5b. Plate-like part 5c. Cylindrical part 6. Low refractive index layer 6a. Clad part 7. High refractive index layer 7a. Core part 8. Color filter layer 10. Solid-state imaging device 11. Microlens 13. Antireflection film 20. Optical waveguide portion 20a. Light exit surface 20c. Lower end 21. Recess 40, 50, 60. Solid-state imaging device 66a. Clad part 66a1. Inner peripheral surface 67. High refractive index layer 67a. Core part 67a1. Outer peripheral surface Reference plane

Claims (14)

  1. 　光電変換部および当該光電変換部により変換された電荷を転送する転送チャネルが設けられた半導体基板と、
    　前記半導体基板の上面を覆い、且つ、前記光電変換部に相当する領域に開口部が設けられた遮光膜と、
    　前記開口部内に設けられた屈折率の異なる複数の透明材料からなり、上方から入射された光を下方に導き光出射面から出射させる光導波路部と、
    を備えた固体撮像装置であって、
    　前記半導体基板の上面の前記転送チャネルに相当する領域を基準面として、当該上面の前記光電変換部に相当する領域に、前記基準面よりも低い凹部が設けられ、
    　前記光導波路部の光出射面が前記半導体基板の凹部内に配置されることにより、当該光出射面が前記半導体基板の基準面よりも低い位置にある
    　ことを特徴とする固体撮像装置。     A semiconductor substrate provided with a photoelectric conversion unit and a transfer channel for transferring charges converted by the photoelectric conversion unit;
    A light-shielding film that covers an upper surface of the semiconductor substrate and has an opening provided in a region corresponding to the photoelectric conversion unit;
    An optical waveguide portion made of a plurality of transparent materials having different refractive indexes provided in the opening, guides light incident from above and emits it from the light exit surface,
    A solid-state imaging device comprising:
    A region corresponding to the transfer channel on the upper surface of the semiconductor substrate is used as a reference surface, and a recess that is lower than the reference surface is provided in a region corresponding to the photoelectric conversion unit on the upper surface,
    The light emitting surface of the optical waveguide portion is disposed in the recess of the semiconductor substrate, so that the light emitting surface is at a position lower than the reference surface of the semiconductor substrate.
  2. 　前記光導波路部が、
    　第１の屈折率の透明材料からなり、前記遮光膜の開口部の内周に沿って形成された筒状のクラッド部と、
    　前記クラッド部の筒内に、前記第１の屈折率よりも高い第２の屈折率の透明材料が埋め込まれてなるコア部とで構成されている
    　ことを特徴とする請求項１に記載の固体撮像装置。     The optical waveguide portion is
    A cylindrical clad formed of a transparent material having a first refractive index and formed along the inner periphery of the opening of the light shielding film;
    2. The solid according to claim 1, comprising: a core portion in which a transparent material having a second refractive index higher than the first refractive index is embedded in a cylinder of the cladding portion. Imaging device.
  3. 　前記第２の屈折率の透明材料が、カラーフィルター用材料である
    　ことを特徴とする請求項２に記載の固体撮像装置。     The solid-state imaging device according to claim 2, wherein the transparent material having the second refractive index is a color filter material.
  4. 　前記クラッド部の内径が、当該クラッド部の上端から下端に向かうにつれて漸次縮小されることにより、その内周面が凹面状に形成されていて、
    　前記コア部の外周面が、前記クラッド部の内周面に沿う凸面状である
    　ことを特徴とする請求項２に記載の固体撮像装置。     By gradually reducing the inner diameter of the cladding part from the upper end to the lower end of the cladding part, the inner peripheral surface is formed in a concave shape,
    The solid-state imaging device according to claim 2, wherein an outer peripheral surface of the core portion is a convex shape along an inner peripheral surface of the clad portion.
  5. 　前記遮光膜が、
    　平板状でありかつ前記光電変換部に相当する領域が開口された板状部分と、
    　当該板状部分の開口縁から下方に向かって延設され、前記開口部を形成する筒状部分と、
    からなり、
    　前記筒状部分の下端が前記半導体基板の凹部内に配置されることにより、前記光導波路部の外周が、前記遮光膜の開口部内から前記凹部内に至るまで前記筒状部分に囲まれている
    　ことを特徴とする請求項１に記載の固体撮像装置。     The light shielding film is
    A plate-like portion that is flat and has an opening corresponding to the photoelectric conversion portion; and
    A cylindrical portion that extends downward from the opening edge of the plate-like portion and forms the opening; and
    Consists of
    Since the lower end of the cylindrical portion is disposed in the recess of the semiconductor substrate, the outer periphery of the optical waveguide portion is surrounded by the cylindrical portion from the opening of the light shielding film to the recess. The solid-state imaging device according to claim 1.
  6. 　前記半導体基板の凹部内に、当該凹部内周面の熱酸化による熱酸化膜が形成されている
    　ことを特徴とする請求項１に記載の固体撮像装置。     2. The solid-state imaging device according to claim 1, wherein a thermal oxide film formed by thermal oxidation of the inner peripheral surface of the recess is formed in the recess of the semiconductor substrate.
  7. 　前記半導体基板は、第１の導電型層と、当該第１の導電型層上に、当該第１の導電型層とは異なる導電型の第２の導電型層とが積層されてなり、
    　前記光電変換部および転送チャネルが、前記第２の導電型層内に配置されており、前記第１の導電型層と同じ導電型である
    　ことを特徴とする請求項１に記載の固体撮像装置。     The semiconductor substrate is formed by laminating a first conductivity type layer and a second conductivity type layer of a conductivity type different from the first conductivity type layer on the first conductivity type layer,
    2. The solid-state imaging device according to claim 1, wherein the photoelectric conversion unit and the transfer channel are disposed in the second conductivity type layer and have the same conductivity type as the first conductivity type layer. .
  8. 　半導体基板内に、光電変換部および当該光電変換部により変換された電荷を転送する転送チャネルを形成する第１の工程と、
    　前記半導体基板の上面を覆いかつ前記光電変換部に相当する領域に開口部が設けられた遮光膜を形成する第２の工程と、
    　前記遮光膜の開口部内に、屈折率の異なる複数の透明材料からなり、上方から入射された光を下方に導き光出射面から出射させる光導波路部を形成する第３の工程と
    を有する固体撮像装置の製造方法であって、
    　前記第１の工程と前記第３の工程との間に、さらに、
    　前記半導体基板の上面の前記転送チャネルに相当する領域を基準面として、当該上面の前記光電変換部に相当する領域に、前記基準面よりも低い凹部を形成する凹部形成工程を有し、
    　前記第３の工程において、
    　前記光導波路部の光出射面を前記半導体基板の凹部内に配置して、当該光出射面の位置を前記半導体基板の基準面よりも低くする
    　ことを特徴とする固体撮像装置の製造方法。     A first step of forming a photoelectric conversion unit and a transfer channel for transferring charges converted by the photoelectric conversion unit in the semiconductor substrate;
    A second step of forming a light shielding film covering an upper surface of the semiconductor substrate and having an opening provided in a region corresponding to the photoelectric conversion unit;
    A solid-state imaging comprising: a third step of forming an optical waveguide portion made of a plurality of transparent materials having different refractive indexes in the opening portion of the light shielding film and guiding light incident from above to be emitted downward from the light exit surface A device manufacturing method comprising:
    Between the first step and the third step,
    A step of forming a recess that is lower than the reference surface in a region corresponding to the photoelectric conversion portion of the upper surface, using a region corresponding to the transfer channel on the upper surface of the semiconductor substrate as a reference surface;
    In the third step,
    A method for manufacturing a solid-state imaging device, wherein a light emitting surface of the optical waveguide portion is disposed in a recess of the semiconductor substrate, and a position of the light emitting surface is lower than a reference surface of the semiconductor substrate.
  9. 　前記凹部形成工程が、
    　前記凹部の深さを第１の深さとして、前記半導体基板の上面の前記光電変換部に相当する領域に、前記第１の深さよりも浅い第２の深さの凹部を形成するサブ工程と、
    　前記半導体基板に形成された前記第２の深さの凹部の底部分を熱酸化して酸化膜を形成するサブ工程と、
    　前記酸化膜を除去することにより、前記半導体基板に、前記第１の深さの凹部を形成するサブ工程とからなる
    　ことを特徴とする請求項８に記載の固体撮像装置の製造方法。     The recess forming step includes
    Forming a recess having a second depth shallower than the first depth in a region corresponding to the photoelectric conversion portion on the upper surface of the semiconductor substrate, the depth of the recess being a first depth; ,
    A sub-process of thermally oxidizing a bottom portion of the second depth recess formed in the semiconductor substrate to form an oxide film;
    The method for manufacturing a solid-state imaging device according to claim 8, further comprising: a sub-step of forming a recess having the first depth in the semiconductor substrate by removing the oxide film.
  10. 　前記凹部形成工程が、さらに、
    　前記第１の深さの凹部を形成するサブ工程の後、
    　前記第１の深さの凹部内周面を熱酸化して熱酸化膜を形成するサブ工程を有する
    　ことを特徴とする請求項９に記載の固体撮像装置の製造方法。     The recess forming step further comprises:
    After the sub-step of forming the first depth recess,
    The method for manufacturing a solid-state imaging device according to claim 9, further comprising a sub-process of thermally oxidizing the inner peripheral surface of the concave portion having the first depth to form a thermal oxide film.
  11. 　前記光導波路部が、屈折率の異なる筒状のクラッド部と、当該クラッド部の筒内に埋め込まれてなるコア部とで構成され、
    　前記第３の工程が、
    　第１の屈折率の透明材料を、前記遮光膜の開口部の内周に沿って筒状にするとともに、当該筒状の下端を前記半導体基板の凹部内に配置するようにして前記クラッド部を形成するサブ工程と、
    　前記クラッド部の筒内に、前記第１の屈折率よりも高い第２の屈折率の透明材料を埋め込むようにして前記コア部を形成するサブ工程とからなる
    　ことを特徴とする請求項８に記載の固体撮像装置の製造方法。     The optical waveguide part is composed of a cylindrical clad part having a different refractive index and a core part embedded in the cylinder of the clad part,
    The third step includes
    The transparent material having the first refractive index is formed in a cylindrical shape along the inner periphery of the opening of the light shielding film, and the cladding portion is disposed so that the lower end of the cylindrical shape is disposed in the recess of the semiconductor substrate. A sub-process to form;
    9. The sub-step of forming the core portion by embedding a transparent material having a second refractive index higher than the first refractive index in the cylinder of the cladding portion. The manufacturing method of the solid-state imaging device of description.
  12. 　前記第１の工程と前記第２の工程との間に、さらに、
    　前記半導体基板上の前記転送チャネルに相当する領域に、前記転送チャネルに対応する転送電極を形成する転送電極形成工程を有し、
    　前記凹部形成工程を、前記第１の工程と前記転送電極形成工程との間に行う
    　ことを特徴とする請求項８に記載の固体撮像装置の製造方法。     Between the first step and the second step,
    A transfer electrode forming step of forming a transfer electrode corresponding to the transfer channel in a region corresponding to the transfer channel on the semiconductor substrate;
    The method for manufacturing a solid-state imaging device according to claim 8, wherein the recess forming step is performed between the first step and the transfer electrode forming step.
  13. 　前記第１の工程と前記第２の工程との間に、さらに、
    　前記半導体基板上の前記転送チャネルに相当する領域に、前記転送チャネルに対応する転送電極を形成する転送電極形成工程を有し、
    　前記凹部形成工程を、前記転送電極形成工程と前記第２の工程との間に行う
    　ことを特徴とする請求項８に記載の固体撮像装置の製造方法。     Between the first step and the second step,
    A transfer electrode forming step of forming a transfer electrode corresponding to the transfer channel in a region corresponding to the transfer channel on the semiconductor substrate;
    The method for manufacturing a solid-state imaging device according to claim 8, wherein the recess forming step is performed between the transfer electrode forming step and the second step.
  14. 　前記凹部形成工程を、前記第２の工程の後に行う
    　ことを特徴とする請求項８に記載の固体撮像装置の製造方法。     The method for manufacturing a solid-state imaging device according to claim 8, wherein the recess forming step is performed after the second step.
PCT/JP2010/007374 2010-06-08 2010-12-20 Solid-state image pickup device and method for manufacturing same WO2011155009A1 (en)

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