WO2013190795A1 - Solid-state imaging element and imaging device - Google Patents
Solid-state imaging element and imaging device Download PDFInfo
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- WO2013190795A1 WO2013190795A1 PCT/JP2013/003605 JP2013003605W WO2013190795A1 WO 2013190795 A1 WO2013190795 A1 WO 2013190795A1 JP 2013003605 W JP2013003605 W JP 2013003605W WO 2013190795 A1 WO2013190795 A1 WO 2013190795A1
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- Prior art keywords
- photoelectric conversion
- filter
- solid
- region
- imaging device
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Images
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L27/00—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate
- H01L27/14—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate including semiconductor components sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation
- H01L27/144—Devices controlled by radiation
- H01L27/146—Imager structures
- H01L27/14601—Structural or functional details thereof
- H01L27/1462—Coatings
- H01L27/14621—Colour filter arrangements
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N25/00—Circuitry of solid-state image sensors [SSIS]; Control thereof
- H04N25/10—Circuitry of solid-state image sensors [SSIS]; Control thereof for transforming different wavelengths into image signals
- H04N25/11—Arrangement of colour filter arrays [CFA]; Filter mosaics
- H04N25/13—Arrangement of colour filter arrays [CFA]; Filter mosaics characterised by the spectral characteristics of the filter elements
- H04N25/134—Arrangement of colour filter arrays [CFA]; Filter mosaics characterised by the spectral characteristics of the filter elements based on three different wavelength filter elements
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L27/00—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate
- H01L27/14—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate including semiconductor components sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation
- H01L27/144—Devices controlled by radiation
- H01L27/146—Imager structures
- H01L27/14643—Photodiode arrays; MOS imagers
- H01L27/14645—Colour imagers
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L27/00—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate
- H01L27/14—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate including semiconductor components sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation
- H01L27/144—Devices controlled by radiation
- H01L27/146—Imager structures
- H01L27/14665—Imagers using a photoconductor layer
- H01L27/14667—Colour imagers
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N25/00—Circuitry of solid-state image sensors [SSIS]; Control thereof
- H04N25/10—Circuitry of solid-state image sensors [SSIS]; Control thereof for transforming different wavelengths into image signals
- H04N25/11—Arrangement of colour filter arrays [CFA]; Filter mosaics
- H04N25/13—Arrangement of colour filter arrays [CFA]; Filter mosaics characterised by the spectral characteristics of the filter elements
- H04N25/133—Arrangement of colour filter arrays [CFA]; Filter mosaics characterised by the spectral characteristics of the filter elements including elements passing panchromatic light, e.g. filters passing white light
Definitions
- the present invention relates to a solid-state imaging device including a photoelectric conversion unit that generates electric charge upon irradiation with light, and an imaging device including the solid-state imaging device.
- pixels including photodiodes are arranged on a semiconductor substrate such as a silicon (Si) chip, Solid-state imaging devices (so-called CCD sensors and CMOS sensors) that acquire signal charges corresponding to photoelectrons generated in a photodiode with a CCD type or CMOS type readout circuit are widely known.
- Si silicon
- B and R light is detected by an image pickup device having a structure in which a three-layer photoelectric conversion film is stacked on a semiconductor substrate on which a signal readout circuit is formed, or a photodiode in the semiconductor substrate, and a photoelectric sensor above the silicon substrate is detected.
- a laminated type image sensor that simultaneously receives light of three colors with one pixel such as an image sensor (Patent Document 3) having a structure in which G light is detected by a conversion element, has been proposed.
- the structure for receiving light has a problem that it is difficult to manufacture and the cost increases.
- a photoelectric conversion part including a pair of electrodes and a photoelectric conversion film sandwiched between these electrodes is provided above a silicon substrate on which a signal readout circuit and the like are formed, and this photoelectric conversion part is the same as in the case of a conventional solid-state imaging device.
- the color filter layer By providing the color filter layer, the charge generated in the photoelectric conversion film through each color filter is transferred from one of the pair of electrodes to the silicon substrate and accumulated, and a signal corresponding to the accumulated charge is transmitted to the silicon substrate.
- a stacked solid-state imaging device that reads with a signal readout circuit formed on a substrate has attracted attention.
- the photoelectric conversion film By forming the photoelectric conversion film as a single film common to all pixels, the light receiving area of each pixel is increased (the aperture ratio is increased) compared to a conventional solid-state imaging device in which a photoelectric conversion unit and a readout circuit are provided in the substrate. Therefore, high sensitivity is expected (Patent Documents 4, 5, etc.).
- FIG. 1 shows the wavelength dependence of the refractive index for each color for the WRGB filter.
- the W filter has a smaller refractive index and less wavelength dependency than the R, G, and B filters.
- light is bent from a medium having a low refractive index toward a medium having a high refractive index.
- FIG. 2 shows a light intrusion region (upward to the right in FIG. 2) between the filters 90B when B light is incident, 90G when G light is incident, and 90R when R light is incident when a general Bayer RGB filter 90 is used.
- It is a schematic plan view showing a region indicated by oblique lines.
- FIG. 3 shows the light between the filters of 95B when the B light is incident, 95G when the G light is incident, and 95R when the R light is incident, in the case of the WRGB filter 95 in which one of the RGB filters of the RGB Bayer arrangement is changed to a W filter.
- FIG. 4 is a schematic plan view showing an intrusion region (a region indicated by an oblique line rising to the right in FIG. 3).
- the size of each filter and the pixel coincide.
- the RGB filter 90 when the RGB filter 90 is used, when B light is incident, only the B pixel transmits light, and the refractive index of the G filter is smaller than that of the B filter in the blue wavelength range. Absent. Further, when R light is incident, only the R pixel transmits light at 90R, and since the refractive index of the G filter is smaller than that of the R filter in the red wavelength region, the light does not spread. On the other hand, at 90G when G light is incident, only the G pixel transmits light, but since the refractive index of the G filter is smaller than that of the R filter and B filter in the green wavelength region, the light spreads. Accordingly, only light that has passed through the G filter enters the surrounding pixels.
- FIG. 4 is a schematic pixel cross-sectional view of a front-illuminated structure of a conventional solid-state image sensor
- FIG. 5 is a schematic cross-sectional view of a pixel of a back-illuminated structure of a conventional solid-state image sensor. 4 and 5, the upper side of the drawing is the light incident side.
- the surface irradiation type imaging device includes a wiring layer 106 and an interlayer insulating layer 105 on a semiconductor substrate 101 on which a photoelectric conversion unit 117 and a signal readout circuit 111 are formed.
- a color filter layer is formed above the interlayer insulating layer 105.
- the photoelectric conversion unit 117 is disposed across an element isolation region in which the signal readout circuit 111 and the like are formed for each pixel.
- a broken line A in FIG. 4 is a boundary of one pixel unit with the photoelectric conversion unit 117 as the center.
- the back-illuminated image sensor receives light from the side opposite to the wiring layer 106 and the interlayer insulating layer 105 formed on the semiconductor substrate 101 on which the photoelectric conversion unit 117 and the signal readout circuit 111 are formed.
- the top and bottom of the surface irradiation type is reversed, and a support substrate 102 is separately provided on the surface that is not on the light incident side.
- the photoelectric conversion unit 117 is arranged with an element isolation region in which the signal readout circuit 111 and the like are formed for each pixel, and the broken line A in FIG. 5 is centered on the photoelectric conversion unit 117 as in the surface irradiation type. Is a boundary of one pixel unit.
- the color filter layer is formed on the surface of the substrate 101 opposite to the surface on which the wiring layer is formed, the wiring layer 106 and the interlayer insulation are provided between the photoelectric conversion unit 117 and the color filter layer.
- the layer 105 is not present.
- the surface irradiation type since these layers are not between the photoelectric conversion part and the color filter layer, the surface irradiation type can receive vignetting light in the wiring layer, etc. The light receiving rate is greatly improved.
- FIG. 6 is a plan view schematically showing a relationship between a pixel region and a light receiving region (a planar view region of a photoelectric conversion unit) of a conventional solid-state imaging device.
- FIG. 7 is a schematic cross-sectional view of a pixel of a multilayer imaging device that is an object of the present invention
- FIG. 8 is a schematic plan view showing the relationship between the pixel region of the multilayer imaging device and a light receiving region (a planar view region of the photoelectric conversion unit).
- a wiring layer 6 and an interlayer insulating layer 5 are formed on a semiconductor substrate 1 on which a signal readout circuit and the like are formed, and the pixels partitioned for each pixel on the wiring layer 6.
- a photoelectric conversion film 14 and a counter electrode 16 provided in common to all the pixels are provided on the electrode 12 and the pixel electrode 12.
- the color filter layer is disposed on the counter electrode 16 via a protective film. The size of one pixel is determined according to the repetition period of the two-dimensionally arranged pixel electrodes. When the photoelectric conversion unit is at the center, an area of one pixel unit is determined with the center line between the pixel electrodes as a boundary, as indicated by a broken line A in FIG.
- the photoelectric conversion film 14 and the counter electrode 16 are formed of a film common to all the pixels in the multilayer imaging device having the above-described configuration, light is irradiated also to the photoelectric conversion film 14 in the gap region between the pixel electrodes 12. Then, a signal charge is generated.
- the signal charge generated in the gap region between the pixel electrodes 12 is collected by each pixel electrode with the center line between the pixel electrodes indicated by the broken line A as a boundary.
- the aperture ratio is 100% because the area of one pixel region and the area where the photoelectric conversion unit can collect signal charges are the same.
- the pixel region delimited by the pixel boundary indicated by the broken line A and the light receiving region match.
- FIGS. 9 and 10 are diagrams showing the light intrusion region in the WRGB filter shown in FIG. 3 superimposed on the plan views of the conventional solid-state imaging device and stacked imaging device shown in FIGS. 6 and 8, respectively.
- the light intrusion area (upward-slashed portion) of the W pixel adjacent pixel does not overlap with the light-receiving area (upward-left diagonal line) of the adjacent pixel (R, B pixel) I understand that. That is, even if light enters another pixel due to the low refractive index of the W filter, color mixture does not occur because it does not enter the photoelectric conversion unit of the other pixel.
- the aperture ratio is 100% in the case of the multilayer image sensor, it can be seen that light transmitted through the W filter enters the light receiving area of other pixels and color mixing occurs. .
- the present invention includes a solid-state imaging device that includes a filter layer having a W filter and can suppress a decrease in S / N due to color mixing, and the solid-state imaging device.
- An object is to provide an imaging device.
- the solid-state imaging device of the present invention has a pixel electrode partitioned on a substrate on a substrate, a photoelectric conversion film that generates a signal charge according to the amount of incident light, and the pixel electrode across the photoelectric conversion film.
- a solid-state imaging device having an imaging unit in which a plurality of pixels having a photoelectric conversion unit including a provided counter electrode are arranged two-dimensionally, The photoelectric conversion film and the counter electrode are formed in a common film shape common to all pixels, A protective film is provided on the counter electrode, On the protective film, color filter layers having different color filters are disposed so that each color filter corresponds to each photoelectric conversion unit, A color filter layer having a plurality of different colors as a color filter, a predetermined color filter that transmits only wavelengths in a predetermined color region, and a white filter that transmits wavelengths in the entire visible light region arranged adjacent to the predetermined color filter And having a refractive index difference between the predetermined color filter and the white filter in at least a visible light region
- the wavelength that is 50% or more of the transmittance of the wavelength having the maximum transmittance among the wavelengths in the visible light region that is transmitted through the filter is the “transmitting” wavelength.
- the wavelength is not transmitted.
- the photoelectric conversion film includes an organic material.
- the predetermined color is any one of blue, green and red.
- a blue filter that transmits only the wavelength of the blue region a green filter that transmits only the wavelength of the green region, and a red filter that transmits only the wavelength of the red region are provided. It is preferable.
- a yellow filter that transmits only the wavelength of the yellow region As the predetermined color filter that transmits only the wavelength of the predetermined color region, a yellow filter that transmits only the wavelength of the yellow region, a magenta filter that transmits only the wavelength of the magenta region, and a cyan filter that transmits only the wavelength of the cyan region. You may prepare.
- a MOS transistor circuit is formed on the substrate to read a signal corresponding to the charge generated in the photoelectric conversion unit.
- the MOS transistor circuit includes a charge storage unit electrically connected to the photoelectric conversion unit, and a potential of the charge storage unit.
- a reset transistor that resets the signal to a reset potential and an output transistor that outputs a signal corresponding to the potential of the charge storage unit.
- the reset transistor and the output transistor collect the polarity of the carrier generated in the photoelectric conversion unit. The polarity is preferably opposite to the charge.
- a functional layer for suppressing dark current is provided between the photoelectric conversion film and the pixel electrode.
- An image pickup apparatus includes the solid-state image pickup element.
- the stacked solid-state image pickup device including the photoelectric conversion film in a film common to all pixels includes the color filter layer including the W filter, and performs photoelectric conversion from the bottom surface of the color filter layer. Since the optical path length d 1 to the upper surface of the film is 1.2 ⁇ m or less and the thickness optical path length d 2 of the photoelectric conversion film is 1.4 ⁇ m or less, color mixing that may occur when a W filter is provided is suppressed, and the S / N The reduction can be prevented, and the effect of increasing the sensitivity by providing the W filter can be sufficiently obtained.
- FIG. 6 is a plan view of the conventional solid-state imaging device shown in FIG. FIG.
- FIG. 8 is a plan view in which a WRGB filter is superimposed on the plan view of the multilayer image sensor shown in FIG. 1 is a schematic cross-sectional view showing a part of a solid-state imaging device according to an embodiment of the present invention.
- Diagram illustrating an optical path length d 2 dependence of the thickness of the photoelectric conversion layer of the color mixing rate The figure which shows the pixel size dependence of the color mixture rate The figure which shows typically a leak to the adjacent pixel of the light which permeate
- DELTA refractive index difference
- FIG. 11 is a cross-sectional view schematically showing a part of the imaging unit (pixel region) of the solid-state imaging device 100 of the present embodiment.
- the imaging unit of the solid-state imaging device 100 includes a semiconductor circuit board 1, an interlayer insulating layer 5 on the semiconductor circuit board 1, and a wiring layer 6 disposed in the insulating layer 5.
- a counter electrode 16 facing the pixel electrode.
- a transparent protective film 18 is laminated on the counter electrode 16, and a color filter layer CF including a plurality of different color filters 21 is provided on the protective film 18.
- FIG. 11 only the white (W) filter 21 w and the blue (B) filter 21 b are shown, but the color filter layer CF further includes a red (R) filter and a green (G) filter in FIG. 3.
- a WRGB filter 95 like the arrangement shown.
- One photoelectric conversion unit 17 is configured by one pixel electrode 12, the photoelectric conversion film 14 on the pixel electrode 12, and the counter electrode 16.
- the photoelectric conversion film on the gap between the adjacent pixel electrodes also contributes to the photoelectric conversion, and the center line between the adjacent pixel electrodes (broken line A in FIG. 11) becomes the boundary between the adjacent photoelectric conversion elements.
- the color filter layer CF corresponds to one color filter for one photoelectric conversion unit, and is arranged so that both areas coincide in plan view.
- the area of the photoelectric conversion unit in plan view and the color filter in plan view The areas at are the same.
- the surface layer of the semiconductor circuit substrate 1 is provided with a signal readout circuit 11 including an accumulation unit for accumulating charges generated in each photoelectric conversion unit 17 and an output circuit for outputting a voltage corresponding to the signal charge of the accumulation unit.
- One pixel unit 20 includes one photoelectric conversion unit 17, a signal readout circuit 11 formed on a substrate surface layer portion below the photoelectric conversion unit 17, and each color filter 21 disposed on the photoelectric conversion unit. In FIG. 11, only the W pixel 20W provided with the W filter and the B pixel 20B provided with the B filter are shown.
- the pixel electrode 12 is a thin film electrode divided for each photoelectric conversion unit 17, and is formed of a transparent or opaque conductive material such as ITO, aluminum, or titanium nitride.
- the pixel electrode 12 collects charges generated in the photoelectric conversion film 14 for each photoelectric conversion unit 17.
- the pixel electrode 12 of each photoelectric conversion unit 17 is electrically connected to the signal readout circuit 11 through a connection unit 7 made of a conductive material so as to penetrate the insulating layer 5.
- the counter electrode 16 is an electrode for applying a voltage to the photoelectric conversion film 14 disposed between the pixel electrode 12 and generating an electric field in the photoelectric conversion film 14, and is formed in a film shape common to all pixels. Has been. Since the counter electrode 16 is provided on the light incident surface side of the photoelectric conversion film 14 and needs to be transmitted through the counter electrode 16 and incident on the photoelectric conversion film 14, the counter electrode 16 is transparent to the incident light. It is formed from a conductive material such as ITO.
- the photoelectric conversion film 14 is made of an organic photoelectric conversion film or an inorganic photoelectric conversion film that absorbs incident light and generates charges according to the absorbed light quantity.
- the aperture ratio can be set to 100% and high sensitivity can be obtained.
- a function such as a charge blocking layer that suppresses the injection of charges from the electrode to the photoelectric conversion film 14 between the photoelectric conversion film 14 and the counter electrode 16 or between the photoelectric conversion film 14 and the pixel electrode 12.
- a layer may be provided.
- a functional layer is provided between the pixel electrode and the photoelectric conversion film, this functional layer is located below the light incident surface of the photoelectric conversion layer and thus does not contribute to color mixing.
- a functional layer is provided between the counter electrode and the photoelectric conversion film, color mixing spreads even in this functional layer. Therefore, the thickness of the functional layer must be as thin as possible to satisfy the optical path length described later.
- a functional layer is provided only on the pixel electrode side, and no functional layer is provided between the counter electrode and the photoelectric conversion film.
- the photoelectric conversion film 14 Since the photoelectric conversion film 14 has an optical path length of 1.4 ⁇ m or less as will be described later, the photoelectric conversion film 14 has a large absorption coefficient so that sufficiently high sensitivity is exhibited even if the film thickness is small, and the absorbed light is signal charge. It is necessary to use a material having a high quantum efficiency for conversion into. Since the silicon film cannot perform sufficient photoelectric conversion with such a thin thickness, it is preferable to use an organic material in order to achieve a sufficiently large absorption coefficient even if it is thin.
- a configuration including a p-type organic semiconductor and an n-type organic semiconductor among organic materials is preferable.
- Exciton dissociation efficiency can be increased by joining a p-type organic semiconductor and an n-type organic semiconductor to form a donor-acceptor interface.
- the photoelectric conversion layer of the structure which joined the p-type organic semiconductor and the n-type organic semiconductor expresses high photoelectric conversion efficiency.
- a photoelectric conversion layer in which a p-type organic semiconductor and an n-type organic semiconductor are mixed is preferable because the junction interface is increased and the photoelectric conversion efficiency is improved.
- the p-type organic semiconductor is a donor organic semiconductor, and when it is an organic semiconductor, it is a compound semiconductor that is mainly represented by a hole-transporting organic compound and has a property of easily donating electrons. More specifically, an organic compound having a smaller ionization potential when two organic materials are used in contact with each other. Therefore, any organic compound can be used as the donor organic semiconductor as long as it is an electron-donating organic compound.
- a metal complex having a nitrogen-containing heterocyclic compound as a ligand can be used. Not limited to this, as described above, any organic compound having an organic compound having an organic compound having anthracene derivatives, phen
- An n-type organic semiconductor is an acceptor semiconductor, and is mainly a compound semiconductor represented by an electron transport compound and having a property of easily accepting electrons. More specifically, an n-type semiconductor refers to a compound having a higher electron affinity when two compounds are used in contact with each other. Therefore, any compound can be used as the acceptor compound as long as it is an electron-accepting compound.
- the n-type semiconductor is not particularly limited.
- a condensed aromatic carbocyclic compound naphthalene derivative, anthracene derivative, phenanthrene derivative, tetracene derivative, pyrene derivative, perylene derivative, fluoranthene derivative
- nitrogen atom oxygen atom
- Any organic dye may be used as the p-type organic semiconductor or the n-type organic semiconductor, but preferably a cyanine dye, a styryl dye, a hemicyanine dye, a merocyanine dye (including zero methine merocyanine (simple merocyanine)), 3 Nuclear merocyanine dye, 4-nuclear merocyanine dye, rhodacyanine dye, complex cyanine dye, complex merocyanine dye, allopolar dye, oxonol dye, hemioxonol dye, squalium dye, croconium dye, azamethine dye, coumarin dye, arylidene dye, anthraquinone dye, tri Phenylmethane dye, azo dye, azomethine dye, spiro compound, metallocene dye, fluorenone dye, fulgide dye, perylene dye, perinone dye, phenazine dye, pheno
- Fullerene means fullerene C60, fullerene C70, fullerene C76, fullerene C78, fullerene C80, fullerene C82, fullerene C84, fullerene C90, fullerene C96, fullerene C240, fullerene 540, mixed fullerene, and fullerene nanotubes. It represents a compound having a substituent added thereto.
- the substituent for the fullerene derivative is preferably an alkyl group, an aryl group, or a heterocyclic group.
- the alkyl group is more preferably an alkyl group having 1 to 12 carbon atoms, and the aryl group and the heterocyclic group are preferably benzene ring, naphthalene ring, anthracene ring, phenanthrene ring, fluorene ring, triphenylene ring, naphthacene ring.
- substituents may further have a substituent, and the substituents may be bonded as much as possible to form a ring.
- substituents may be bonded as much as possible to form a ring.
- you may have a some substituent and they may be the same or different.
- a plurality of substituents may be combined as much as possible to form a ring.
- the photoelectric conversion layer contains fullerene or a fullerene derivative
- electrons generated by photoelectric conversion can be quickly transported to the pixel electrode or the counter electrode via the fullerene molecule or the fullerene derivative molecule.
- fullerene molecules or fullerene derivative molecules are connected to form an electron path, the electron transport property is improved, and the high-speed response of the photoelectric conversion element can be realized.
- the p-type organic semiconductor is reduced, the junction interface is reduced, and the exciton dissociation efficiency is lowered.
- the photoelectric conversion layer as a p-type organic semiconductor mixed with fullerene or a fullerene derivative, when a triarylamine compound described in Japanese Patent No. 4213832 is used, high absorption and high quantum efficiency can be expressed even in a thin film, Particularly preferred. If the ratio of fullerene or fullerene derivative in the photoelectric conversion layer is too large, the amount of the triarylamine compound is reduced and the amount of incident light absorbed is reduced. As a result, the photoelectric conversion efficiency is reduced, so that the fullerene or fullerene derivative contained in the photoelectric conversion layer preferably has a composition of 85% or less. With this configuration, d 2 can be set to 1.0 to 1.2 over the entire visible light range while exhibiting high sensitivity in the photoelectric conversion layer.
- the protective film 18 has a function of protecting the photoelectric conversion layer from deterioration factors such as water molecules and oxygen, particularly when the photoelectric conversion film includes an organic material.
- the protective film 18 has a function of protecting the photoelectric conversion layer by preventing intrusion of a factor that degrades the performance of the photoelectric conversion layer contained in a solution such as an organic solvent or plasma in each manufacturing process of the image sensor 10. Bear.
- intrusion of factors such as water molecules and oxygen that degrade the performance of the photoelectric conversion layer is prevented to prevent the performance deterioration of the photoelectric conversion layer over a long period of storage and long-term use. To do. Further, incident light (visible light) reaches the photoelectric conversion film 14 through the protective film 18.
- the protective film 18 is transparent to light having a wavelength detected by the photoelectric conversion element 17 and visible light.
- the protective film 18 preferably has a light transmittance of 60% or more, more preferably 80% or more, more preferably 90% or more, and even more preferably 95% or more.
- the thickness of the protective film is approximately 50 to 1000 nm, but is determined within a range that satisfies the conditions described later. However, when the thickness of the protective film 18 is less than 50 nm, there is a possibility that the barrier property is lowered and the resistance of the color filter to the developer is lowered. On the other hand, a thick protective film 18 leads to an increase in color mixture as will be described later. Therefore, the protective film 18 is preferably thin.
- the protective film is particularly preferably an inorganic material film formed by vapor phase deposition. It is easier to obtain a film having a higher protection performance with an inorganic material than with an organic material even with a thin film.
- the vapor deposition method can provide a dense film as compared with other film formation methods, and thus high protection performance can be obtained even with a thin film.
- the CVD method is particularly preferable because a dense film can be obtained. Further, since the film forming speed is high, it is suitable for manufacturing.
- the ALCVD method is particularly suitable for reducing the thickness of the protective film because a particularly dense film can be obtained.
- AlOx aluminum oxide
- SiOx silicon oxide
- SiNx silicon nitride
- SiON silicon oxynitride
- SiON formed by CVD can change the refractive index and protection performance by changing the film formation conditions and adjusting the ratio of O and N, and high protection performance can be obtained with a short optical path length.
- AlOx formed by the ALCVD method can obtain high protection performance even with a film thickness of 100 nm or less, which is almost an order of magnitude smaller than other film forming methods. Therefore, for example, a laminated film of 100 nm or less of AlOx formed by ALCVD and 100 to 500 nm of SiON formed by CVD is very preferable from the viewpoint of optical path length and protection performance.
- a functional layer such as an antireflection layer or a color filter adhesion enhancing layer may be provided between the protective film and the color filter.
- a functional layer such as an antireflection layer or a color filter adhesion enhancing layer may be provided between the protective film and the color filter.
- a functional layer for improving the function of the photoelectric conversion element specifically, a charge blocking layer for reducing dark current is provided between the photoelectric conversion film 14 and the pixel electrode. Yes.
- the photoelectric conversion film is thin, there is a high risk of dark current increase due to a short circuit or a leak, so that the dark current suppression effect by providing the charge blocking layer is high. .
- the color filter layer CF is disposed and formed so that each filter 21 is located at a position facing each pixel electrode 12 on the protective film 18. As shown in FIG. 3, the color filter layer CF includes a color filter that transmits light of different wavelengths of R, G, and B and a W filter that transmits the entire visible light. Each of the R, G, and B filters is formed of an organic material containing a red / blue / green pigment or dye.
- Each color filter is generally formed by exposing and developing a color resist with ultraviolet rays.
- the color resist is composed of pigments of various colors, a photo-curing resin, a viscosity adjusting agent, and the like.
- the refractive index of the color filter after pattern formation by exposure and development is determined by the main component pigment and the photo-curing resin. Therefore, as shown in FIG. 1, the refractive index of the color filter differs for each color of WRGB, and also differs depending on the wavelength of incident light.
- FIG. 1 shows an example of a WRGB filter. However, since each color filter of a color filter layer generally uses a photo-curing resin, the refractive index difference for each color itself is the same as that in FIG. 0 to 0.4.
- the optical path length d 1 from the bottom surface of the color filter layer CF to the photoelectric conversion film 14 is 1.2 ⁇ m or less, and the optical path length d 2 of the thickness of the photoelectric conversion film 14 is 1.4 ⁇ m or less.
- the protective film 18 and the counter electrode 16 are provided between the color filter layer CF and the photoelectric conversion film 14, but other layers may be included.
- the optical path length is represented by the product of the spatial distance and refractive index, wherein the optical path length d 1 is to have a layer of a plurality of different refractive index, it is represented by the sum of the optical path length of each layer.
- the optical path length d 1 n 1. t 1 + n 2 ⁇ t 2 .
- the present inventor has conducted various studies and found that the color mixing ratio can be sufficiently reduced at least within the above range.
- the investigation that has led to the finding that the above range is preferable will be described below.
- the refractive index difference between W and R, G, and B is about 0.4 or less as shown in FIG. . If the difference in refractive index is sufficiently small, almost no color mixing occurs. According to the study by the present inventors, if the difference in refractive index is less than 0.1, color mixing that causes a problem did not occur. In view of this, the difference in refractive index between the W pixel and the other pixels was assumed to be about 0.1 to 0.4. In addition, the case where incident light enters vertically from above the filter was studied.
- the distance from the bottom surface of the filter to the bottom surface of the photoelectric conversion film was examined.
- the imaging device having the configuration shown in FIG. 11 when the refractive index difference between two adjacent filters of different colors is 0.1 and 0.4, the photoelectric conversion from the low refractive index filter to the high refractive index filter side is performed.
- the color mixing ratio due to the light incident on the part was examined by changing d 1 and d 2 .
- the pixel size is 3 ⁇ m.
- the leakage of light from the W pixel to the B pixel when R light (650 nm) was incident was examined. Since the R light transmittance of the B filter is almost 0, it is considered that all signals of the B pixel are caused by leakage. Therefore, the signal charge generated in the B pixel divided by the pixel size (3 ⁇ m) was plotted as a color mixture ratio.
- ⁇ n 0.1
- the leakage of light from the W pixel to the R pixel when B light (450 nm) was incident was examined. Since the B light transmittance of the R filter is almost 0, it is considered that all signals of the R pixel are caused by leakage. Therefore, the signal mixture generated by dividing the signal charge generated in the R pixel by the pixel size (3 ⁇ m) was plotted as the color mixture ratio.
- FIG. 12 is a graph showing the dependence of the color mixture ratio on d 1 when d 2 is 1.4 ⁇ m. As shown in FIG. 12, the color mixture rate hardly changed when d 1 was 1.2 ⁇ m or less, but rapidly increased when d 1 exceeded 1.2 ⁇ m.
- FIG. 13 is a graph showing the d 2 dependency of the color mixture rate when d 1 is 1.2 ⁇ m. As shown in FIG. 13, the color mixing ratio is hardly changed by d 2 is 1.4 [mu] m or less, and rapidly increase exceeds 1.4 [mu] m.
- FIG. 15 is a diagram schematically illustrating leakage of light transmitted through the W filter to adjacent pixels in the solid-state imaging device.
- the thickness is indicated by the optical path length, not the actual film thickness.
- the light transmitted through the W color filter gradually leaks to the adjacent pixels in the protective film and the photoelectric conversion film due to the difference in refractive index between the W color filter and the adjacent color filter.
- the leakage does not increase linearly with respect to the depth direction, but the leakage region is narrow in the upper part near the color filter, and the leakage region spreads rapidly as the depth increases.
- the light absorbed by the photoelectric conversion layer of the adjacent pixel causes color mixing.
- the leakage region is the same, a large amount of signal charge is generated at the upper part of the photoelectric conversion layer, and the signal charge generated at the lower part of the photoelectric conversion layer is Few. That is, it is important to narrow the leak region above the photoelectric conversion layer. This indicates that when the value of d 1 is large, the leakage area at the upper part of the photoelectric conversion layer becomes large and the color mixture increases drastically. As shown in FIG. 12, d 1 is 1.2 ⁇ m or less. It is necessary to reduce color mixing.
- the area of the leakage region increases nonlinearly as d 2 increases.
- d 2 exceeds 1.4 ⁇ m
- the color mixture increases explosively, so d 2 needs to be 1.4 ⁇ m or less.
- a color filter layer including a W filter is provided, from the bottom surface of the color filter layer to the upper surface of the photoelectric conversion film. of 1.2 ⁇ m below the optical path length d 1, and the thickness optical path length d 2 of the photoelectric conversion layer and below 1.4 [mu] m.
- 16 and 17 are diagrams schematically showing leakage of light transmitted through the W filter to adjacent pixels when the refractive index difference ⁇ n is 0.2, 0, and 4, respectively. As shown in FIGS. 16 and 17, the leakage area increases as the refractive index difference ⁇ n increases. From FIG. 16 and FIG. 17, when the refractive index difference ⁇ n is increased, the leakage region is spread so as to increase rapidly.
- the leakage region has a complicated shape that expands as it goes in the depth direction, and light is absorbed in the photoelectric conversion film so that there is a slight amount below the photoelectric conversion unit. Since this is a complicated phenomenon such as the arrival of only light, an appropriate correlation between the refractive index difference ⁇ n and d 1 and d 2 for controlling color mixing cannot be uniquely determined.
- an appropriate relational expression (for example, ⁇ n ⁇ (d 1 + d 2 )) is predicted between d 1 , d 2 and the refractive index difference ⁇ n for the obtained data, and the color mixing rate and By plotting the relationship, a condition under which color mixing can be more effectively suppressed under conditions where d 1 is 1.2 ⁇ m or less and d 2 is 1.4 ⁇ m or less was searched. As a result, it was found that color mixing can be more effectively suppressed by setting ⁇ n ⁇ (d 1 + d 2 ) 2 to 2.0 or less as shown in FIG.
- FIG. 19 is based on the result of FIG. 18, and in the case where d 1 is 1.2 ⁇ m or less and d 2 is 1.4 ⁇ m or less, ⁇ n ⁇ (d 1 + d 2 ) 2 is plotted on the horizontal axis and the color mixing ratio is plotted on the vertical axis. Is a graph in which is plotted. As shown in FIG. 19, when ⁇ n ⁇ (d 1 + d 2 ) 2 changes greatly from 2.0 as a boundary, and ⁇ n ⁇ (d 1 + d 2 ) 2 becomes 2.0 or more, 2 It has been found that the increase in color mixture becomes remarkable as compared with the case of less than 0.0. That is, ⁇ n ⁇ (d 1 + d 2 ) 2 ⁇ 2.0 It was found that color mixing can be suppressed more effectively.
- the color filter array is an array in which one of G of RGB Bayer arrays is replaced with W.
- the color filter array is not limited to the above array and can be arbitrarily changed. is there.
- a complementary color filter may be provided, or a color filter layer including four types of color filters of yellow, magenta, cyan, and white may be provided. Even in that case, since white generally has the smallest refractive index, light oozes out from the white pixel to other pixels in the same manner, so that the optical path lengths d 1 and d 2 are controlled as in the above embodiment. As a result, the influence of light oozing can be suppressed, and a high S / N image can be acquired.
- FIG. 20 is a circuit diagram showing the signal readout circuit 11 in each pixel unit 20 and the relationship between the circuit unit 11 and the photoelectric conversion unit 17.
- an output transistor 32, a reset transistor 33, and a selection transistor 34 are formed in the signal readout circuit 11.
- the output transistor 32, the reset transistor 33, and the selection transistor 34 are each composed of an n-channel MOS transistor.
- the photoelectric conversion unit 17 and the gate of the output transistor 32 are electrically connected, and this node is referred to as a floating diffusion FD (hereinafter simply referred to as FD).
- FD floating diffusion FD
- the signal readout circuit 11 is shown as one region, but in reality, the above-described elements are formed in this region.
- a bias voltage is applied to the pixel electrode 12 such that holes out of the charges generated in the photoelectric conversion film 14 move to the pixel electrode 12 and electrons move to the counter electrode 16.
- a bias voltage a voltage (5 V) higher than the power supply voltage Vdd of the readout circuit (voltage supplied to the drain of the output transistor in FIG. 20, for example, 3 V) so that the photoelectric conversion film 14 exhibits sufficiently high sensitivity. It is desirable to use about 20V, for example 10V).
- FD is a node including an n-type impurity region electrically connected to the pixel electrode 12.
- the FD has a capacitance due to the parasitic capacitance of the photoelectric conversion unit 17 and each transistor. Since the potential of the FD changes according to the amount of charges collected by the pixel electrode 12, the FD functions as a charge storage unit.
- the output transistor 32 converts the charge signal accumulated in the FD into a voltage signal and outputs it to the signal line.
- the gate terminal of the output transistor 32 is electrically connected to the FD, and the drain terminal is connected to the power supply voltage Vdd of the solid-state imaging device.
- the source terminal of the output transistor 32 is connected to the drain terminal of the selection transistor 34.
- the pixel unit 20 in the present embodiment is a circuit having a so-called three-transistor configuration in which the FD, the pixel electrode 12 of the photoelectric conversion unit 17, and the gate terminal of the output transistor 32 are electrically connected directly.
- the reset transistor 33 resets the potential of the FD to the reference potential.
- the FD is electrically connected to the drain terminal of the reset transistor 33, the reset power source is connected to the source terminal, and the voltage RD is supplied.
- the reset pulse RS applied to the gate terminal of the reset transistor 33 becomes high level, the reset transistor 33 is turned on, and electrons are injected from the source to the drain of the reset transistor 33. Then, due to the injection of electrons, the potential of the FD drops and the potential of the FD is reset to the reference potential.
- the selection transistor 34 has a source terminal connected to the signal line, and selectively outputs a signal output from the output transistor 32 of each pixel to a signal line provided for each column. . When the selection pulse RW applied to the gate terminal of the selection transistor 34 becomes a high level, the selection transistor 34 is turned on, whereby a signal output from the output transistor 32 of each pixel is output to the signal line.
- the signal readout circuit 11 is configured by the reset transistor 33, the output transistor 32, and the selection transistor 34 are n-channel MOS transistors, and holes are collected by the pixel electrode 12.
- the present invention is not limited thereto, and the reset transistor 33, the output transistor 32, and the selection transistor 34 are configured by p-channel MOS transistors, and electrons are collected by the pixel electrode 12, and a charge signal corresponding to the amount of the electrons is obtained. Reading may be performed by the signal reading circuit 11 configured by a p-channel MOS transistor.
- holes are collected by the pixel electrode 12 and read out by the signal readout circuit 11 constituted by an n-channel MOS transistor, or electrons are collected by the pixel electrode 12 as described above.
- the signal readout circuit 11 configured by a p-channel MOS transistor
- the electron is collected by the pixel electrode and read out by a signal readout circuit configured from an n-channel MOS transistor.
- the number of saturated electrons can be increased, and the dynamic range of the W pixel which is easily saturated can be increased.
- the photodiode formed in the conventional silicon substrate since the signal readout circuit and the photodiode are formed in the same substrate, the polarity of the readout circuit and the polarity of the collected charge could not be reversed. .
- FIG. 21 is a diagram showing an overall configuration of the solid-state imaging device 100 of the present embodiment.
- the solid-state imaging device 100 of the present embodiment includes a vertical driver 121, a control unit 122, a signal processing circuit 123, a horizontal driver 124, an LVDS 125, a serial conversion unit 126, a pad 127, and the like. And a pixel region (corresponding to an imaging unit) in which a plurality of pixel units 20 shown in FIG. 11 are arranged two-dimensionally. In the pixel region of FIG. 21, only the signal readout circuit 11 of the pixel unit 20 is schematically shown.
- the control unit 122 includes a timing generator and the like, outputs the frame synchronization signal VD and the row synchronization signal HD, and controls the operations of the vertical driver 121 and the horizontal driver 124 to control the charge signal in the pixel unit 20. It controls reading and the like.
- the vertical driver 121 outputs a reset pulse RS and a selection pulse RW to the signal readout circuit 11 based on the frame synchronization signal VD and the row synchronization signal HD output from the control unit 122, and a reset operation in the signal readout circuit 11. And the charge signal reading operation.
- the signal processing circuit 123 is provided corresponding to each column of the signal readout circuit 11.
- the signal processing circuit 123 includes an ADC circuit that performs correlated double sampling (CDS) processing on the signals output from the corresponding columns and converts the processed signals into digital signals.
- CDS correlated double sampling
- the signal processed by the signal processing circuit 123 is stored in a memory provided for each column.
- the horizontal driver 124 controls to sequentially read out signals for one row of the pixel unit 20 stored in the memory of the signal processing circuit 123 and output the signals to the LVDS 125.
- the LVDS 125 transmits a digital signal in accordance with LVDS (low voltage differential).
- the serial conversion unit 126 converts an input parallel digital signal into a serial signal and outputs it.
- the pad 127 is an interface used for input / output with the outside.
- the configuration in which the microlens is not provided on the color filter has been described, but the microlens may be provided on the color filter.
- the solid-state imaging device of the above-described embodiment can be used for various imaging devices.
- the imaging device include a digital camera, a digital video camera, an electronic endoscope, and a camera-equipped mobile phone.
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Abstract
[Problem] To prevent color mixing that occurs in a solid-state imaging element having a configuration comprising W pixels. [Solution] A solid-state imaging element having a color filter layer (CF) having a plurality of different colored color filters (21) arranged upon a plurality of photoelectric conversion units (17) arranged two-dimensionally upon a substrate (1), said color filters arranged such that each color filter (21) corresponds 1:1 to each photoelectric conversion unit (17). The solid-state imaging element comprises: pixel electrodes (12) having the photoelectric conversion units (17) partitioned at each pixel; a photoelectric conversion film (14) common to all pixels; and a facing electrode (16) arranged facing the pixel electrodes (12) and having the photoelectric conversion film (14) interposed therebetween. The optical path length (d1) from the bottom surface of the color filter layer (CF) to the upper surface of the photoelectric conversion film (14) is no more than 1.2 µm and the optical path length (d2) for the thickness of the photoelectric conversion film (14) is no more than 1.4 µm.
Description
本発明は、光の照射を受けて電荷を発生する光電変換部を備えた固体撮像素子およびその固体撮像素子を備えた撮像装置に関するものである。
The present invention relates to a solid-state imaging device including a photoelectric conversion unit that generates electric charge upon irradiation with light, and an imaging device including the solid-state imaging device.
テジタルスチルカメラ、デジタルビデオカメラ、携帯電話用カメラ、内視鏡用カメラ等に利用されているイメージセンサとして、シリコン(Si)チップなどの半導体基板にフォトダイオードを含む画素を配列し、各画素のフォトダイオードで発生した光電子に対応する信号電荷をCCD型やCMOS型読出し回路で取得する、固体撮像素子(所謂CCDセンサやCMOSセンサ)が広く知られている。
As an image sensor used for a digital still camera, a digital video camera, a mobile phone camera, an endoscope camera, etc., pixels including photodiodes are arranged on a semiconductor substrate such as a silicon (Si) chip, Solid-state imaging devices (so-called CCD sensors and CMOS sensors) that acquire signal charges corresponding to photoelectrons generated in a photodiode with a CCD type or CMOS type readout circuit are widely known.
近年、固体撮像素子の画素微細化が進んでいる。画素を微細化すると各画素に入射するフォトン数が減少するため、一般に画像の感度が低下するという問題が伴う。そこで、高感度化を図るために、色フィルタ配列にWhite画素(白画素)を導入し、WRGBカラーフィルタを備えることが提案されている(特許文献1、特許文献2など。)。
In recent years, pixel miniaturization of solid-state imaging devices has progressed. When a pixel is miniaturized, the number of photons incident on each pixel decreases, so that there is a problem that the sensitivity of an image generally decreases. Therefore, in order to achieve high sensitivity, it has been proposed to introduce a white pixel (white pixel) into the color filter array and to include a WRGB color filter (Patent Document 1, Patent Document 2, etc.).
従来型の撮像素子としては、シリコンなどの半導体基板内に光電変換部が読出し回路と共に形成された構成が一般的である。しかしながら、光電変換部と読出し回路を基板内に備えるために、微細化に伴い、光電変換部の開口率の低下、集光効率の低下が問題となっている。
As a conventional imaging device, a configuration in which a photoelectric conversion unit is formed together with a readout circuit in a semiconductor substrate such as silicon is common. However, since the photoelectric conversion unit and the readout circuit are provided in the substrate, a decrease in the aperture ratio of the photoelectric conversion unit and a decrease in the light collection efficiency have become problems with miniaturization.
また、信号読出回路が形成された半導体基板の上に3層の光電変換膜を積層する構造の撮像素子や、半導体基板内のフォトダイオードでBとRの光を検出し、シリコン基板上方の光電変換素子でGの光検出する構造の撮像素子(特許文献3)などの1画素で3色の受光を同時行う積層型の撮像素子も提案されているが、このような1画素で複数色の受光を行う構造は、作製が困難でコストが嵩むという問題がある。
In addition, B and R light is detected by an image pickup device having a structure in which a three-layer photoelectric conversion film is stacked on a semiconductor substrate on which a signal readout circuit is formed, or a photodiode in the semiconductor substrate, and a photoelectric sensor above the silicon substrate is detected. A laminated type image sensor that simultaneously receives light of three colors with one pixel, such as an image sensor (Patent Document 3) having a structure in which G light is detected by a conversion element, has been proposed. The structure for receiving light has a problem that it is difficult to manufacture and the cost increases.
一方、信号読出し回路等が形成されたシリコン基板の上方に一対の電極とこれらで挟まれた光電変換膜を含む光電変換部を設け、この光電変換部上に従来の固体撮像素子の場合と同様のカラーフィルタ層を備えることにより、各カラーフィルタを透過して光電変換膜で発生した電荷を上記一対の電極の一方からシリコン基板に移動させて蓄積し、この蓄積電荷に応じた信号を、シリコン基板に形成した信号読出し回路で読み出す積層型の固体撮像素子が近年注目されている。光電変換膜を全画素に共通の1枚膜として形成することにより、光電変換部と読出し回路を基板内に設けた従来の固体撮像素子と比べて、各画素の受光領域を大きく(開口率をほぼ100%に)することができるため、高感度化が期待されている(特許文献4、5等)。
On the other hand, a photoelectric conversion part including a pair of electrodes and a photoelectric conversion film sandwiched between these electrodes is provided above a silicon substrate on which a signal readout circuit and the like are formed, and this photoelectric conversion part is the same as in the case of a conventional solid-state imaging device. By providing the color filter layer, the charge generated in the photoelectric conversion film through each color filter is transferred from one of the pair of electrodes to the silicon substrate and accumulated, and a signal corresponding to the accumulated charge is transmitted to the silicon substrate. In recent years, a stacked solid-state imaging device that reads with a signal readout circuit formed on a substrate has attracted attention. By forming the photoelectric conversion film as a single film common to all pixels, the light receiving area of each pixel is increased (the aperture ratio is increased) compared to a conventional solid-state imaging device in which a photoelectric conversion unit and a readout circuit are provided in the substrate. Therefore, high sensitivity is expected (Patent Documents 4, 5, etc.).
特許文献4、5等に記載の積層型の固体撮像素子においても、特許文献1、2等に記載のW画素を備えたフィルタ配列を適用することにより、さらなる微細化、高感度化を図ることができると考えられる。
Even in the stacked solid-state imaging device described in Patent Documents 4 and 5, etc., further miniaturization and higher sensitivity can be achieved by applying the filter array including the W pixels described in Patent Documents 1 and 2 and the like. It is thought that you can.
しかしながら、この積層型の固体撮像素子にW画素を適用するに当たり、開口率100%ならではの別の問題が生じることが発明者の検討により明らかになった。以下にその問題点について詳細に説明する。
However, when the W pixel is applied to the stacked solid-state imaging device, it has been clarified by the inventors that another problem unique to an aperture ratio of 100% occurs. The problem will be described in detail below.
本発明者は、W画素を含むフィルタ層を単に積層型撮像素子に備えた場合、Wフィルタとそれ以外の色フィルタとの間の屈折率差によって、Wフィルタに入射した光が他の色フィルタ側に曲がるという現象から混色の問題が生じ、S/Nの低下に繋がることを見出した。WRGBフィルタについて、各色毎の屈折率の波長依存性を図1に示す。図1に示すように、WフィルタはR、G、Bフィルタと比較して屈折率が小さく、波長依存性も小さい。一般に、光は屈折率の低い媒質から屈折率の高い媒質側に曲がる。
When the inventor simply includes a filter layer including a W pixel in a multilayer image sensor, light incident on the W filter is changed to another color filter due to a refractive index difference between the W filter and the other color filters. It has been found that the problem of color mixing arises from the phenomenon of bending to the side, leading to a decrease in S / N. FIG. 1 shows the wavelength dependence of the refractive index for each color for the WRGB filter. As shown in FIG. 1, the W filter has a smaller refractive index and less wavelength dependency than the R, G, and B filters. In general, light is bent from a medium having a low refractive index toward a medium having a high refractive index.
図2は、一般的なベイヤー配列のRGBフィルタ90を用いた場合の、B光入射時90B、G光入射時90G、R光入射時90Rの各フィルタ間における光侵入領域(図2中右上がり斜線で示す領域)を示す平面模式図である。また、図3は、RGBベイヤー配列のGフィルタの1つをWフィルタに変更したWRGBフィルタ95の場合の、B光入射時95B、G光入射時95G、R光入射95Rの各フィルタ間における光侵入領域(図3中右上がり斜線で示す領域)を示す平面模式図である。ここで、各フィルタと画素の大きさは一致している。
FIG. 2 shows a light intrusion region (upward to the right in FIG. 2) between the filters 90B when B light is incident, 90G when G light is incident, and 90R when R light is incident when a general Bayer RGB filter 90 is used. It is a schematic plan view showing a region indicated by oblique lines. FIG. 3 shows the light between the filters of 95B when the B light is incident, 95G when the G light is incident, and 95R when the R light is incident, in the case of the WRGB filter 95 in which one of the RGB filters of the RGB Bayer arrangement is changed to a W filter. FIG. 4 is a schematic plan view showing an intrusion region (a region indicated by an oblique line rising to the right in FIG. 3). Here, the size of each filter and the pixel coincide.
図2に示すように、RGBフィルタ90を用いた場合、B光入射時90BはB画素のみ光が透過し、青色波長域においてGフィルタの屈折率はBフィルタより小さいため、光の広がりは起こらない。また、R光入射時90RはR画素のみ光が透過し、赤色波長域においてGフィルタの屈折率がRフィルタより小さいため、光の広がりは起こらない。一方、G光入射時90Gは、G画素のみ光が透過するが、緑色波長域においてGフィルタの屈折率がRフィルタ、Bフィルタより小さいため、光の広がりが起こる。したがって、Gフィルタを通った光のみが周辺の画素に侵入する。
As shown in FIG. 2, when the RGB filter 90 is used, when B light is incident, only the B pixel transmits light, and the refractive index of the G filter is smaller than that of the B filter in the blue wavelength range. Absent. Further, when R light is incident, only the R pixel transmits light at 90R, and since the refractive index of the G filter is smaller than that of the R filter in the red wavelength region, the light does not spread. On the other hand, at 90G when G light is incident, only the G pixel transmits light, but since the refractive index of the G filter is smaller than that of the R filter and B filter in the green wavelength region, the light spreads. Accordingly, only light that has passed through the G filter enters the surrounding pixels.
一方、図3に示すように、WRGBフィルタ95を用いた場合、B光入射時95BはB画素およびW画素で光が透過し、青色波長域においてWフィルタの屈折率がRフィルタより小さいため、WフィルタからRフィルタへの広がりが起こる。また、R光入射時95RはR画素およびW画素で光が透過し、赤色波長域においてWフィルタの屈折率がBフィルタより小さいため、光の広がりが起こる。さらに、G光入射時95Gは、G画素、W画素で光が透過し、緑色波長域においてWフィルタ、Gフィルタの屈折率がRフィルタ、Bフィルタより小さいため、光の広がりが起こる。すなわち、RGBフィルタのみを用いた場合はG画素からの光の漏れ出しのみなのに対し、Wフィルタを用いた場合には、各画素間で非常に複雑な光の侵入が発生することが分かる。
On the other hand, as shown in FIG. 3, when the WRGB filter 95 is used, light is transmitted through the B pixel and the W pixel when the B light is incident 95B, and the refractive index of the W filter is smaller than the R filter in the blue wavelength region. The spread from the W filter to the R filter occurs. In addition, when R light is incident, light is transmitted through the R pixel and the W pixel, and the light spreads because the refractive index of the W filter is smaller than that of the B filter in the red wavelength region. Further, at G light incidence 95G, light is transmitted through the G pixel and W pixel, and the light spreads because the refractive index of the W filter and G filter is smaller than that of the R filter and B filter in the green wavelength region. That is, when only the RGB filter is used, only light leaks from the G pixel, whereas when the W filter is used, very complicated light intrusion occurs between the pixels.
これらの侵入光が光電変換部で受光され信号電荷が発生してしまうと混色となる。Wフィルタを用いない場合には、侵入光の色も決まっているため、信号処理等で混色を低減することも可能ではあるが、Wフィルタを用いた場合には非常に複雑な混色となってしまい、信号処理等による低減も難しい。このため、このような光の侵入がおこらないように全てのカラーフィルタの屈折率を揃えることが出来れば望ましい。しかし実際には、色分離のためにカラーフィルタの吸収率を調整しながら、屈折率も揃えるという極めて困難である。
When these intrusion lights are received by the photoelectric conversion unit and signal charges are generated, color mixing occurs. When the W filter is not used, the color of the intrusion light is determined, so it is possible to reduce the color mixture by signal processing or the like. However, when the W filter is used, the color mixture becomes very complicated. Therefore, reduction by signal processing or the like is difficult. Therefore, it is desirable if the refractive indexes of all the color filters can be made uniform so that such light intrusion does not occur. However, in practice, it is extremely difficult to adjust the refractive index while adjusting the absorption rate of the color filter for color separation.
続いて、受光部の構造について説明する。図4、図5には従来の固体撮像素子の構成を示している。図4は従来の固体撮像素子のうち表面照射型構造の画素断面模式図であり、図5は従来の固体撮像素子のうち裏面照射型構造の画素断面模式図である。なお、図4、5において、紙面上方が光入射側である。
Next, the structure of the light receiving part will be described. 4 and 5 show the configuration of a conventional solid-state imaging device. FIG. 4 is a schematic pixel cross-sectional view of a front-illuminated structure of a conventional solid-state image sensor, and FIG. 5 is a schematic cross-sectional view of a pixel of a back-illuminated structure of a conventional solid-state image sensor. 4 and 5, the upper side of the drawing is the light incident side.
図4に示すように、表面照射型の撮像素子は、光電変換部117および信号読出回路111が形成された半導体基板101上に配線層106および層間絶縁層105を備えている。通常、この層間絶縁層105上方にカラーフィルタ層が形成される。光電変換部117は各画素毎に信号読出回路111等が形成された素子分離領域を隔てて配置されている。図4中破線Aが光電変換部117を中心とする1画素単位の境界である。
As shown in FIG. 4, the surface irradiation type imaging device includes a wiring layer 106 and an interlayer insulating layer 105 on a semiconductor substrate 101 on which a photoelectric conversion unit 117 and a signal readout circuit 111 are formed. Usually, a color filter layer is formed above the interlayer insulating layer 105. The photoelectric conversion unit 117 is disposed across an element isolation region in which the signal readout circuit 111 and the like are formed for each pixel. A broken line A in FIG. 4 is a boundary of one pixel unit with the photoelectric conversion unit 117 as the center.
図5に示すように、裏面照射型の撮像素子は、光電変換部117および信号読出回路111が形成された半導体基板101上に形成された配線層106および層間絶縁層105とは反対側から受光する構成となっており、表面照射型とは天地が逆となっており、光入射側でない面には別途、支持基板102が設けられている。なお、光電変換部117は各画素毎に信号読出回路111等が形成された素子分離領域を隔てて配置されており、表面照射型と同様に、図5中破線Aが光電変換部117を中心とする1画素単位の境界である。なお、この場合、基板101の配線層が形成されている面とは逆の面側にカラーフィルタ層は形成されるため、光電変換部117とカラーフィルタ層との間に配線層106および層間絶縁層105が存在しない構成となる。表面照射型と異なり、光電変換部とカラーフィルタ層との間にこれらの層がないことから、表面照射型では配線層等でケラレていた光を受光することができ、表面照射型に比べて受光率を大幅に改善する構成となっている。
As shown in FIG. 5, the back-illuminated image sensor receives light from the side opposite to the wiring layer 106 and the interlayer insulating layer 105 formed on the semiconductor substrate 101 on which the photoelectric conversion unit 117 and the signal readout circuit 111 are formed. The top and bottom of the surface irradiation type is reversed, and a support substrate 102 is separately provided on the surface that is not on the light incident side. Note that the photoelectric conversion unit 117 is arranged with an element isolation region in which the signal readout circuit 111 and the like are formed for each pixel, and the broken line A in FIG. 5 is centered on the photoelectric conversion unit 117 as in the surface irradiation type. Is a boundary of one pixel unit. In this case, since the color filter layer is formed on the surface of the substrate 101 opposite to the surface on which the wiring layer is formed, the wiring layer 106 and the interlayer insulation are provided between the photoelectric conversion unit 117 and the color filter layer. The layer 105 is not present. Unlike the surface irradiation type, since these layers are not between the photoelectric conversion part and the color filter layer, the surface irradiation type can receive vignetting light in the wiring layer, etc. The light receiving rate is greatly improved.
図6は従来の固体撮像素子の画素領域と受光領域(光電変換部の平面視領域)との関係を模式的に示す平面図である。表面照射型、裏面照射型いずれであっても同様であり、画素領域(図6において点線Aで示す領域)に対して光電変換部117による受光領域(図6において左上がり斜線で示す領域)は一回り小さい。これは、前述の通り光電変換部117と信号読出回路111を同一基板中に設け、光電変換部117を各画素毎に素子分離する必要があるためである。
FIG. 6 is a plan view schematically showing a relationship between a pixel region and a light receiving region (a planar view region of a photoelectric conversion unit) of a conventional solid-state imaging device. The same applies to both the front-side irradiation type and the back-side irradiation type, and the light-receiving region (region indicated by a left-upward oblique line in FIG. 6) of the photoelectric conversion unit 117 with respect to the pixel region (region indicated by a dotted line A in FIG. 6) A little smaller. This is because it is necessary to provide the photoelectric conversion unit 117 and the signal readout circuit 111 on the same substrate as described above, and to separate the photoelectric conversion unit 117 for each pixel.
次に、積層型の固体撮像素子の構成を簡単に説明する。図7は本発明の対象となる積層型撮像素子の画素断面模式図であり、図8は積層型撮像素子の画素領域と受光領域(光電変換部の平面視領域)との関係を示す平面模式図である。
Next, the configuration of the stacked solid-state imaging device will be briefly described. FIG. 7 is a schematic cross-sectional view of a pixel of a multilayer imaging device that is an object of the present invention, and FIG. 8 is a schematic plan view showing the relationship between the pixel region of the multilayer imaging device and a light receiving region (a planar view region of the photoelectric conversion unit). FIG.
図7に示すように、積層型撮像素子は、信号読出し回路等が形成された半導体基板1上に配線層6および層間絶縁層5が形成され、その上に、各画素毎に区画された画素電極12、画素電極12上に全画素に共通して設けられる光電変換膜14および対向電極16を備えている。一般に、カラーフィルタ層は、対向電極16上に保護膜を介して配置される。1画素のサイズは二次元状に配列された画素電極の繰り返し周期に応じて決定される。光電変換部を中心にすると、図7中破線Aで示すように画素電極間の中心線を境界として1画素単位の領域が決定される。
As shown in FIG. 7, in the multilayer image pickup device, a wiring layer 6 and an interlayer insulating layer 5 are formed on a semiconductor substrate 1 on which a signal readout circuit and the like are formed, and the pixels partitioned for each pixel on the wiring layer 6. A photoelectric conversion film 14 and a counter electrode 16 provided in common to all the pixels are provided on the electrode 12 and the pixel electrode 12. In general, the color filter layer is disposed on the counter electrode 16 via a protective film. The size of one pixel is determined according to the repetition period of the two-dimensionally arranged pixel electrodes. When the photoelectric conversion unit is at the center, an area of one pixel unit is determined with the center line between the pixel electrodes as a boundary, as indicated by a broken line A in FIG.
上記構成の積層型撮像素子では光電変換膜14および対向電極16が全画素に共通の膜で形成されていることから、画素電極間12の隙間の領域における光電変換膜14においても、光が照射されると信号電荷が発生する。画素電極間12の隙間の領域で発生した信号電荷は破線Aで示した画素電極間の中心線を境として、それぞれの画素電極に捕集される。1画素の領域の面積と光電変換部が信号電荷を捕集できる面積が一致していることから開口率が100%である。
Since the photoelectric conversion film 14 and the counter electrode 16 are formed of a film common to all the pixels in the multilayer imaging device having the above-described configuration, light is irradiated also to the photoelectric conversion film 14 in the gap region between the pixel electrodes 12. Then, a signal charge is generated. The signal charge generated in the gap region between the pixel electrodes 12 is collected by each pixel electrode with the center line between the pixel electrodes indicated by the broken line A as a boundary. The aperture ratio is 100% because the area of one pixel region and the area where the photoelectric conversion unit can collect signal charges are the same.
つまり、図8に示すように、破線Aで示される画素境界で区切られる画素領域と、受光領域(左上がり斜線で示す領域)とが一致している。
That is, as shown in FIG. 8, the pixel region delimited by the pixel boundary indicated by the broken line A and the light receiving region (the region indicated by the left-upward oblique line) match.
さて、図9および図10は、図3に示したWRGBフィルタにおける光の侵入領域を図6および8の従来の固体撮像素子および積層型撮像素子の平面図とそれぞれ重ねて示した図である。
9 and 10 are diagrams showing the light intrusion region in the WRGB filter shown in FIG. 3 superimposed on the plan views of the conventional solid-state imaging device and stacked imaging device shown in FIGS. 6 and 8, respectively.
図9に示すように、従来の固体撮像素子ではW画素の隣接画素への光の侵入領域(右上がり斜線部)が隣接画素(R,B画素)の受光領域(左上がり斜線)と重ならないことが分かる。つまりWフィルタの低い屈折率の影響により光が他の画素に侵入したとしても、他の画素の光電変換部には入射しないため、混色が生じないのである。一方、図10に示すように、積層型撮像素子の場合には、開口率が100%であるため、Wフィルタを透過した光が他画素の受光領域に入射してしまい混色が生じることが分かる。
従って、積層型撮像素子において、Wフィルタを有するフィルタ層を適用する際には、従来の固体撮像素子では生じない新たな混色が発生するため、S/Nが低下しないようにこの混色を抑制することが大きな課題となる。 As shown in FIG. 9, in the conventional solid-state imaging device, the light intrusion area (upward-slashed portion) of the W pixel adjacent pixel does not overlap with the light-receiving area (upward-left diagonal line) of the adjacent pixel (R, B pixel) I understand that. That is, even if light enters another pixel due to the low refractive index of the W filter, color mixture does not occur because it does not enter the photoelectric conversion unit of the other pixel. On the other hand, as shown in FIG. 10, since the aperture ratio is 100% in the case of the multilayer image sensor, it can be seen that light transmitted through the W filter enters the light receiving area of other pixels and color mixing occurs. .
Therefore, when a filter layer having a W filter is applied to a multilayer image sensor, a new color mixture that does not occur in a conventional solid-state image sensor occurs, and thus this color mixture is suppressed so that S / N does not decrease. This is a big issue.
従って、積層型撮像素子において、Wフィルタを有するフィルタ層を適用する際には、従来の固体撮像素子では生じない新たな混色が発生するため、S/Nが低下しないようにこの混色を抑制することが大きな課題となる。 As shown in FIG. 9, in the conventional solid-state imaging device, the light intrusion area (upward-slashed portion) of the W pixel adjacent pixel does not overlap with the light-receiving area (upward-left diagonal line) of the adjacent pixel (R, B pixel) I understand that. That is, even if light enters another pixel due to the low refractive index of the W filter, color mixture does not occur because it does not enter the photoelectric conversion unit of the other pixel. On the other hand, as shown in FIG. 10, since the aperture ratio is 100% in the case of the multilayer image sensor, it can be seen that light transmitted through the W filter enters the light receiving area of other pixels and color mixing occurs. .
Therefore, when a filter layer having a W filter is applied to a multilayer image sensor, a new color mixture that does not occur in a conventional solid-state image sensor occurs, and thus this color mixture is suppressed so that S / N does not decrease. This is a big issue.
本発明は、上記の事情に鑑み、積層型撮像素子において、Wフィルタを有するフィルタ層を備え、かつ混色によるS/Nの低下を抑制することができる固体撮像素子およびその固体撮像素子を備えた撮像装置を提供することを目的とする。
In view of the above circumstances, the present invention includes a solid-state imaging device that includes a filter layer having a W filter and can suppress a decrease in S / N due to color mixing, and the solid-state imaging device. An object is to provide an imaging device.
本発明の固体撮像素子は、基板上に画素単位で区画された画素電極、入射光の光量に応じた信号電荷を発生する光電変換膜、およびその光電変換膜を挟んで画素電極に対向して設けられた対向電極を含む光電変換部を有する画素が、二次元状に複数配列されてなる撮像部を有する固体撮像素子において、
光電変換膜および対向電極が、全ての画素に共通な共通膜状に形成されてなり、
対向電極上に保護膜を備え、
保護膜上に、異なる複数色のカラーフィルタを有するカラーフィルタ層が、各カラーフィルタが各光電変換部と対応するように配置され、
カラーフィルタ層が、異なる複数色のカラーフィルタとして、所定の色領域の波長のみを透過する所定色フィルタと、所定色フィルタに隣接して配置された全可視光領域に亘る波長を透過する白色フィルタとを含み、少なくとも所定の色領域の波長以外の可視光領域において、所定色フィルタと白色フィルタとの間に屈折率差を有するものであり、
カラーフィルタ層の底面から光電変換膜の上面までの光路長d1が1.2μm以下であり、
光電変換膜の厚みの光路長d2が1.4μm以下であることを特徴とする。 The solid-state imaging device of the present invention has a pixel electrode partitioned on a substrate on a substrate, a photoelectric conversion film that generates a signal charge according to the amount of incident light, and the pixel electrode across the photoelectric conversion film. In a solid-state imaging device having an imaging unit in which a plurality of pixels having a photoelectric conversion unit including a provided counter electrode are arranged two-dimensionally,
The photoelectric conversion film and the counter electrode are formed in a common film shape common to all pixels,
A protective film is provided on the counter electrode,
On the protective film, color filter layers having different color filters are disposed so that each color filter corresponds to each photoelectric conversion unit,
A color filter layer having a plurality of different colors as a color filter, a predetermined color filter that transmits only wavelengths in a predetermined color region, and a white filter that transmits wavelengths in the entire visible light region arranged adjacent to the predetermined color filter And having a refractive index difference between the predetermined color filter and the white filter in at least a visible light region other than the wavelength of the predetermined color region,
The optical path length d 1 from the bottom surface of the color filter layer to the top surface of the photoelectric conversion film is 1.2 μm or less,
The optical path length d 2 of the thickness of the photoelectric conversion film is equal to or less than 1.4 [mu] m.
光電変換膜および対向電極が、全ての画素に共通な共通膜状に形成されてなり、
対向電極上に保護膜を備え、
保護膜上に、異なる複数色のカラーフィルタを有するカラーフィルタ層が、各カラーフィルタが各光電変換部と対応するように配置され、
カラーフィルタ層が、異なる複数色のカラーフィルタとして、所定の色領域の波長のみを透過する所定色フィルタと、所定色フィルタに隣接して配置された全可視光領域に亘る波長を透過する白色フィルタとを含み、少なくとも所定の色領域の波長以外の可視光領域において、所定色フィルタと白色フィルタとの間に屈折率差を有するものであり、
カラーフィルタ層の底面から光電変換膜の上面までの光路長d1が1.2μm以下であり、
光電変換膜の厚みの光路長d2が1.4μm以下であることを特徴とする。 The solid-state imaging device of the present invention has a pixel electrode partitioned on a substrate on a substrate, a photoelectric conversion film that generates a signal charge according to the amount of incident light, and the pixel electrode across the photoelectric conversion film. In a solid-state imaging device having an imaging unit in which a plurality of pixels having a photoelectric conversion unit including a provided counter electrode are arranged two-dimensionally,
The photoelectric conversion film and the counter electrode are formed in a common film shape common to all pixels,
A protective film is provided on the counter electrode,
On the protective film, color filter layers having different color filters are disposed so that each color filter corresponds to each photoelectric conversion unit,
A color filter layer having a plurality of different colors as a color filter, a predetermined color filter that transmits only wavelengths in a predetermined color region, and a white filter that transmits wavelengths in the entire visible light region arranged adjacent to the predetermined color filter And having a refractive index difference between the predetermined color filter and the white filter in at least a visible light region other than the wavelength of the predetermined color region,
The optical path length d 1 from the bottom surface of the color filter layer to the top surface of the photoelectric conversion film is 1.2 μm or less,
The optical path length d 2 of the thickness of the photoelectric conversion film is equal to or less than 1.4 [mu] m.
ここで、フィルタを透過する可視光領域の波長のうち最大透過率を有する波長の透過率の50%以上でそのフィルタを透過する波長は「透過する」波長であり、50%未満であれば「透過してない」波長とする。
Here, the wavelength that is 50% or more of the transmittance of the wavelength having the maximum transmittance among the wavelengths in the visible light region that is transmitted through the filter is the “transmitting” wavelength. The wavelength is not transmitted.
本発明の固体撮像素子においては、光電変換膜が有機材料を含むものであることが好ましい。
In the solid-state imaging device of the present invention, it is preferable that the photoelectric conversion film includes an organic material.
白色フィルタと所定色フィルタとの屈折率差をΔnとすると、所定色フィルタが透過しない可視光波長領域全域においてΔnと光路長d1(μm)、d2(μm)との間に、
Δn × (d1+d2)2< 2.0
の関係が成り立つことが好ましい。 When the refractive index difference between the white color filter and the predetermined color filter is Δn, between Δn and the optical path lengths d 1 (μm) and d 2 (μm) in the entire visible light wavelength region where the predetermined color filter does not transmit,
Δn × (d 1 + d 2 ) 2 <2.0
It is preferable that this relationship is established.
Δn × (d1+d2)2< 2.0
の関係が成り立つことが好ましい。 When the refractive index difference between the white color filter and the predetermined color filter is Δn, between Δn and the optical path lengths d 1 (μm) and d 2 (μm) in the entire visible light wavelength region where the predetermined color filter does not transmit,
Δn × (d 1 + d 2 ) 2 <2.0
It is preferable that this relationship is established.
上記所定の色が青、緑および赤のいずれかであることが好ましい。
It is preferable that the predetermined color is any one of blue, green and red.
所定の色領域の波長のみを透過する所定色フィルタとして、青色領域の波長のみを透過する青色フィルタ、緑色領域の波長のみを透過する緑色フィルタ、および赤色領域の波長のみを透過する赤色フィルタを備えることが好ましい。
As the predetermined color filter that transmits only the wavelength of the predetermined color region, a blue filter that transmits only the wavelength of the blue region, a green filter that transmits only the wavelength of the green region, and a red filter that transmits only the wavelength of the red region are provided. It is preferable.
上記所定の色領域の波長のみを透過する所定色カラーフィルタとして、黄色領域の波長のみを透過する黄色フィルタ、マゼンダ領域の波長のみを透過するマゼンダフィルタ、シアン領域の波長のみを透過するシアンフィルタを備えてもよい。
As the predetermined color filter that transmits only the wavelength of the predetermined color region, a yellow filter that transmits only the wavelength of the yellow region, a magenta filter that transmits only the wavelength of the magenta region, and a cyan filter that transmits only the wavelength of the cyan region. You may prepare.
基板に光電変換部において生じる電荷に応じた信号を読み出すMOSトランジスタ回路が形成されており、そのMOSトランジスタ回路は、光電変換部と電気的に接続された電荷蓄積部と、その電荷蓄積部の電位をリセット電位にリセットするリセットトランジスタと、電荷蓄積部の電位に応じた信号を出力する出力トランジスタとを含み、リセットトランジスタ及び出力トランジスタは、キャリアの極性が前記光電変換部で発生した捕集される電荷と逆極性であることが好ましい。
A MOS transistor circuit is formed on the substrate to read a signal corresponding to the charge generated in the photoelectric conversion unit. The MOS transistor circuit includes a charge storage unit electrically connected to the photoelectric conversion unit, and a potential of the charge storage unit. A reset transistor that resets the signal to a reset potential and an output transistor that outputs a signal corresponding to the potential of the charge storage unit. The reset transistor and the output transistor collect the polarity of the carrier generated in the photoelectric conversion unit. The polarity is preferably opposite to the charge.
光電変換膜と画素電極との間に、暗電流を抑制する機能層が設けられていることが好ましい。
It is preferable that a functional layer for suppressing dark current is provided between the photoelectric conversion film and the pixel electrode.
本発明の撮像装置は、上記固体撮像素子を備えたことを特徴とするものである。
An image pickup apparatus according to the present invention includes the solid-state image pickup element.
本発明の固体撮像素子および撮像装置によれば、全画素共通膜状の光電変換膜を備えた積層型の固体撮像素子において、Wフィルタを含むカラーフィルタ層を備え、カラーフィルタ層底面から光電変換膜の上面までの光路長d1を1.2μm以下、光電変換膜の厚み光路長d2を1.4μm以下としているので、Wフィルタを備えた場合に生じ得る混色を抑制してS/N低下を防止することができ、Wフィルタを備えることによる高感度化の効果を十分に得ることできる。
According to the solid-state image pickup device and the image pickup apparatus of the present invention, the stacked solid-state image pickup device including the photoelectric conversion film in a film common to all pixels includes the color filter layer including the W filter, and performs photoelectric conversion from the bottom surface of the color filter layer. Since the optical path length d 1 to the upper surface of the film is 1.2 μm or less and the thickness optical path length d 2 of the photoelectric conversion film is 1.4 μm or less, color mixing that may occur when a W filter is provided is suppressed, and the S / N The reduction can be prevented, and the effect of increasing the sensitivity by providing the W filter can be sufficiently obtained.
以下、図面を参照して本発明の固体撮像素子の実施形態について説明する。
図11は、本実施形態の固体撮像素子100の撮像部(画素領域)の一部を模式的に示す断面図である。 Hereinafter, embodiments of a solid-state imaging device of the present invention will be described with reference to the drawings.
FIG. 11 is a cross-sectional view schematically showing a part of the imaging unit (pixel region) of the solid-state imaging device 100 of the present embodiment.
図11は、本実施形態の固体撮像素子100の撮像部(画素領域)の一部を模式的に示す断面図である。 Hereinafter, embodiments of a solid-state imaging device of the present invention will be described with reference to the drawings.
FIG. 11 is a cross-sectional view schematically showing a part of the imaging unit (pixel region) of the solid-
図11に示すように、固体撮像素子100の撮像部は、半導体回路基板1と、半導体回路基板1上に層間絶縁層5およびその絶縁層5中に配された配線層6を介して、2次元状に配置された複数の画素電極(下部電極)12と、複数の画素電極12上に共通して形成された有機材料からなる光電変換膜14と、光電変換膜14上に形成された複数の画素電極に対向する対向電極16とを備えている。また、対向電極16の上には透明な保護膜18が積層されており、この保護膜18上に、互いに異なる複数色のカラーフィルタ21を備えたカラーフィルタ層CFが設けられている。図11においては、白(W)フィルタ21wおよび青(B)フィルタ21bのみが示されているが、カラーフィルタ層CFは、さらに赤(R)フィルタおよび緑(G)フィルタを備えた図3に示す配列のようなWRGBフィルタ95である。
As shown in FIG. 11, the imaging unit of the solid-state imaging device 100 includes a semiconductor circuit board 1, an interlayer insulating layer 5 on the semiconductor circuit board 1, and a wiring layer 6 disposed in the insulating layer 5. A plurality of pixel electrodes (lower electrodes) 12 arranged in a dimension, a photoelectric conversion film 14 made of an organic material formed in common on the plurality of pixel electrodes 12, and a plurality formed on the photoelectric conversion film 14 And a counter electrode 16 facing the pixel electrode. A transparent protective film 18 is laminated on the counter electrode 16, and a color filter layer CF including a plurality of different color filters 21 is provided on the protective film 18. In FIG. 11, only the white (W) filter 21 w and the blue (B) filter 21 b are shown, but the color filter layer CF further includes a red (R) filter and a green (G) filter in FIG. 3. A WRGB filter 95 like the arrangement shown.
1つの画素電極12と該画素電極12上の光電変換膜14および対向電極16により1つの光電変換部17が構成されている。隣接する画素電極間の隙間上の光電変換膜も光電変換に寄与するものであり、隣接する画素電極間の中心線(図11中の破線A)が隣接する光電変換素子の境界となる。
One photoelectric conversion unit 17 is configured by one pixel electrode 12, the photoelectric conversion film 14 on the pixel electrode 12, and the counter electrode 16. The photoelectric conversion film on the gap between the adjacent pixel electrodes also contributes to the photoelectric conversion, and the center line between the adjacent pixel electrodes (broken line A in FIG. 11) becomes the boundary between the adjacent photoelectric conversion elements.
カラーフィルタ層CFは、1つの光電変換部につき1つのカラーフィルタが対応し、平面視において両者の領域が一致するように配置されており、光電変換部の平面視における面積とカラーフィルタの平面視における面積は同一である。
The color filter layer CF corresponds to one color filter for one photoelectric conversion unit, and is arranged so that both areas coincide in plan view. The area of the photoelectric conversion unit in plan view and the color filter in plan view The areas at are the same.
半導体回路基板1の表層には、各光電変換部17において発生した電荷を蓄積する蓄積部および該蓄積部の信号電荷に応じた電圧を出力する出力回路を含む信号読出回路11が備えられており、1つの画素部20は、1つの光電変換部17、その下方の基板表層部に形成された信号読出回路11および光電変換部上に配置された各色フィルタ21を含んでなる。なお、図11においては、Wフィルタを備えたW画素20W、Bフィルタを備えたB画素20Bのみが示されている。
The surface layer of the semiconductor circuit substrate 1 is provided with a signal readout circuit 11 including an accumulation unit for accumulating charges generated in each photoelectric conversion unit 17 and an output circuit for outputting a voltage corresponding to the signal charge of the accumulation unit. One pixel unit 20 includes one photoelectric conversion unit 17, a signal readout circuit 11 formed on a substrate surface layer portion below the photoelectric conversion unit 17, and each color filter 21 disposed on the photoelectric conversion unit. In FIG. 11, only the W pixel 20W provided with the W filter and the B pixel 20B provided with the B filter are shown.
画素電極12は、光電変換部17毎に区分された薄膜電極であり、たとえばITOやアルミニウムや窒化チタンなどのような透明または不透明な導電性材料から形成されるものである。画素電極12は、光電変換膜14において発生した電荷を光電変換部17毎に捕集するものである。各光電変換部17の画素電極12は、絶縁層5を貫通するように形成された導電性材料からなる接続部7を介して信号読出回路11に電気的に接続されている。
The pixel electrode 12 is a thin film electrode divided for each photoelectric conversion unit 17, and is formed of a transparent or opaque conductive material such as ITO, aluminum, or titanium nitride. The pixel electrode 12 collects charges generated in the photoelectric conversion film 14 for each photoelectric conversion unit 17. The pixel electrode 12 of each photoelectric conversion unit 17 is electrically connected to the signal readout circuit 11 through a connection unit 7 made of a conductive material so as to penetrate the insulating layer 5.
対向電極16は、画素電極12との間に配置されている光電変換膜14に電圧を印加し、光電変換膜14に電界を生じさせるための電極であり、全画素に共通な膜状に形成されている。対向電極16は、光電変換膜14よりも光の入射面側に設けられており、対向電極16を透過して光電変換膜14に光を入射させる必要があるため、入射光に対して透明なITOなどの導電性材料から形成される。
The counter electrode 16 is an electrode for applying a voltage to the photoelectric conversion film 14 disposed between the pixel electrode 12 and generating an electric field in the photoelectric conversion film 14, and is formed in a film shape common to all pixels. Has been. Since the counter electrode 16 is provided on the light incident surface side of the photoelectric conversion film 14 and needs to be transmitted through the counter electrode 16 and incident on the photoelectric conversion film 14, the counter electrode 16 is transparent to the incident light. It is formed from a conductive material such as ITO.
光電変換膜14は、入射光を吸収し、その吸収した光量に応じた電荷を発生する有機光電変換膜または無機光電変換膜からなる。光電変換膜14を全画素共通の膜とすることで開口率を100%とし、高い感度を得ることができる。なお、光電変換膜14と対向電極16との間、または光電変換膜14と画素電極12との間に、電極から光電変換膜14へ電荷が注入されるのを抑制する電荷ブロッキング層などの機能層を設けるようにしてもよい。
The photoelectric conversion film 14 is made of an organic photoelectric conversion film or an inorganic photoelectric conversion film that absorbs incident light and generates charges according to the absorbed light quantity. By using the photoelectric conversion film 14 as a film common to all the pixels, the aperture ratio can be set to 100% and high sensitivity can be obtained. A function such as a charge blocking layer that suppresses the injection of charges from the electrode to the photoelectric conversion film 14 between the photoelectric conversion film 14 and the counter electrode 16 or between the photoelectric conversion film 14 and the pixel electrode 12. A layer may be provided.
なお、画素電極と光電変換膜の間に機能層を設けた場合、この機能層は光電変換層よりも光の入射面に対して下にあるため、混色には寄与しない。一方、対向電極と光電変換膜の間に機能層を設けた場合、この機能層中でも混色が広がるため、この機能層の厚みは出来る限り薄く、後述する光路長を満たすことが必要である。好ましくは、画素電極側にのみ機能層を有し、対向電極と光電変換膜の間には機能層を有さない。
Note that when a functional layer is provided between the pixel electrode and the photoelectric conversion film, this functional layer is located below the light incident surface of the photoelectric conversion layer and thus does not contribute to color mixing. On the other hand, when a functional layer is provided between the counter electrode and the photoelectric conversion film, color mixing spreads even in this functional layer. Therefore, the thickness of the functional layer must be as thin as possible to satisfy the optical path length described later. Preferably, a functional layer is provided only on the pixel electrode side, and no functional layer is provided between the counter electrode and the photoelectric conversion film.
光電変換膜14は、後述の通りその厚みを光路長で1.4μm以下とするため、膜厚が小さくても十分に高い感度が発現するように吸収係数の大きく、かつ吸収した光を信号電荷に変換する量子効率が高い材料を用いることが必要である。シリコン膜では、そのような薄い厚みで十分な光電変換を行うことができないため、薄くても十分大きい吸収係数を達成するためには有機材料を用いることが好ましい。
Since the photoelectric conversion film 14 has an optical path length of 1.4 μm or less as will be described later, the photoelectric conversion film 14 has a large absorption coefficient so that sufficiently high sensitivity is exhibited even if the film thickness is small, and the absorbed light is signal charge. It is necessary to use a material having a high quantum efficiency for conversion into. Since the silicon film cannot perform sufficient photoelectric conversion with such a thin thickness, it is preferable to use an organic material in order to achieve a sufficiently large absorption coefficient even if it is thin.
高い量子効率を得るには、有機材料の中でも特にp型有機半導体とn型有機半導体とを含む構成が好ましい。p型有機半導体とn型有機半導体を接合させてドナ‐アクセプタ界面を形成することにより励起子解離効率を増加させることができる。このために、p型有機半導体とn型有機半導体を接合させた構成の光電変換層は高い光電変換効率を発現する。特に、p型有機半導体とn型有機半導体を混合した光電変換層は、接合界面が増大して光電変換効率が向上するので好ましい。
In order to obtain high quantum efficiency, a configuration including a p-type organic semiconductor and an n-type organic semiconductor among organic materials is preferable. Exciton dissociation efficiency can be increased by joining a p-type organic semiconductor and an n-type organic semiconductor to form a donor-acceptor interface. For this reason, the photoelectric conversion layer of the structure which joined the p-type organic semiconductor and the n-type organic semiconductor expresses high photoelectric conversion efficiency. In particular, a photoelectric conversion layer in which a p-type organic semiconductor and an n-type organic semiconductor are mixed is preferable because the junction interface is increased and the photoelectric conversion efficiency is improved.
p型有機半導体(化合物)は、ドナ性有機半導体であり、有機半導体である場合は、主に正孔輸送性有機化合物に代表され、電子を供与しやすい性質がある化合物半導体をいう。さらに詳しくは2つの有機材料を接触させて用いたときにイオン化ポテンシャルの小さい方の有機化合物をいう。したがって、ドナ性有機半導体としては、電子供与性のある有機化合物であればいずれの有機化合物も使用可能である。
The p-type organic semiconductor (compound) is a donor organic semiconductor, and when it is an organic semiconductor, it is a compound semiconductor that is mainly represented by a hole-transporting organic compound and has a property of easily donating electrons. More specifically, an organic compound having a smaller ionization potential when two organic materials are used in contact with each other. Therefore, any organic compound can be used as the donor organic semiconductor as long as it is an electron-donating organic compound.
p型半導体としては、特に限定されないが、例えば、トリアリールアミン化合物、ベンジジン化合物、ピラゾリン化合物、スチリルアミン化合物、ヒドラゾン化合物、トリフェニルメタン化合物、カルバゾール化合物、ポリシラン化合物、チオフェン化合物、フタロシアニン化合物、シアニン化合物、メロシアニン化合物、オキソノール化合物、ポリアミン化合物、インドール化合物、ピロール化合物、ピラゾール化合物、ポリアリーレン化合物、縮合芳香族炭素環化合物(ナフタレン誘導体、アントラセン誘導体、フェナントレン誘導体、テトラセン誘導体、ピレン誘導体、ペリレン誘導体、フルオランテン誘導体)、含窒素ヘテロ環化合物を配位子として有する金属錯体等を用いることができる。なお、これに限らず、上記したように、n型(アクセプタ性)化合物として用いた有機化合物よりもイオン化ポテンシャルの小さい有機化合物であればドナー性有機半導体として用いてよい。
Although it does not specifically limit as a p-type semiconductor, For example, a triarylamine compound, a benzidine compound, a pyrazoline compound, a styrylamine compound, a hydrazone compound, a triphenylmethane compound, a carbazole compound, a polysilane compound, a thiophene compound, a phthalocyanine compound, a cyanine compound , Merocyanine compounds, oxonol compounds, polyamine compounds, indole compounds, pyrrole compounds, pyrazole compounds, polyarylene compounds, condensed aromatic carbocyclic compounds (naphthalene derivatives, anthracene derivatives, phenanthrene derivatives, tetracene derivatives, pyrene derivatives, perylene derivatives, fluoranthene derivatives ), A metal complex having a nitrogen-containing heterocyclic compound as a ligand can be used. Not limited to this, as described above, any organic compound having an ionization potential smaller than that of the organic compound used as the n-type (acceptor) compound may be used as the donor organic semiconductor.
n型有機半導体(化合物)は、アクセプタ性半導体であり、主に電子輸送性化合物に代表され、電子を受容しやすい性質がある化合物半導体をいう。さらに詳しくは、n型半導体とは、2つの化合物を接触させて用いたときに電子親和力の大きい方の化合物をいう。したがって、アクセプタ性化合物は、電子受容性のある化合物であればいずれの化合物も使用可能である。
An n-type organic semiconductor (compound) is an acceptor semiconductor, and is mainly a compound semiconductor represented by an electron transport compound and having a property of easily accepting electrons. More specifically, an n-type semiconductor refers to a compound having a higher electron affinity when two compounds are used in contact with each other. Therefore, any compound can be used as the acceptor compound as long as it is an electron-accepting compound.
n型半導体としては、特に限定されないが、例えば、縮合芳香族炭素環化合物(ナフタレン誘導体、アントラセン誘導体、フェナントレン誘導体、テトラセン誘導体、ピレン誘導体、ペリレン誘導体、フルオランテン誘導体)、窒素原子、酸素原子、硫黄原子を含有する5~7員のヘテロ環化合物(例えばピリジン、ピラジン、ピリミジン、ピリダジン、トリアジン、キノリン、キノキサリン、キナゾリン、フタラジン、シンノリン、イソキノリン、プテリジン、アクリジン、フェナジン、フェナントロリン、テトラゾール、ピラゾール、イミダゾール、チアゾール、オキサゾール、インダゾール、ベンズイミダゾール、ベンゾトリアゾール、ベンゾオキサゾール、ベンゾチアゾール、カルバゾール、プリン、トリアゾロピリダジン、トリアゾロピリミジン、テトラザインデン、オキサジアゾール、イミダゾピリジン、ピラリジン、ピロロピリジン、チアジアゾロピリジン、ジベンズアゼピン、トリベンズアゼピン等)、ポリアリーレン化合物、フルオレン化合物、シクロペンタジエン化合物、シリル化合物、含窒素ヘテロ環化合物を配位子として有する金属錯体などが挙げられる。なお、これに限らず、上記したように、p型(ドナ性)化合物として用いた化合物よりも電子親和力の大きな化合物であればアクセプタ性半導体として用いてよい。
The n-type semiconductor is not particularly limited. For example, a condensed aromatic carbocyclic compound (naphthalene derivative, anthracene derivative, phenanthrene derivative, tetracene derivative, pyrene derivative, perylene derivative, fluoranthene derivative), nitrogen atom, oxygen atom, sulfur atom 5- to 7-membered heterocyclic compounds containing, for example, pyridine, pyrazine, pyrimidine, pyridazine, triazine, quinoline, quinoxaline, quinazoline, phthalazine, cinnoline, isoquinoline, pteridine, acridine, phenazine, phenanthroline, tetrazole, pyrazole, imidazole, thiazole , Oxazole, indazole, benzimidazole, benzotriazole, benzoxazole, benzothiazole, carbazole, purine, triazolopyridazine, tri Zolopyrimidine, tetrazaindene, oxadiazole, imidazopyridine, pyralidine, pyrrolopyridine, thiadiazolopyridine, dibenzazepine, tribenzazepine, etc.), polyarylene compounds, fluorene compounds, cyclopentadiene compounds, silyl compounds, nitrogen-containing heterocycles Examples thereof include metal complexes having a compound as a ligand. However, the present invention is not limited thereto, and as described above, any compound having an electron affinity higher than that of the compound used as the p-type (donor) compound may be used as the acceptor semiconductor.
p型有機半導体、又はn型有機半導体としては、いかなる有機色素を用いても良いが、好ましくは、シアニン色素、スチリル色素、ヘミシアニン色素、メロシアニン色素(ゼロメチンメロシアニン(シンプルメロシアニン)を含む)、3核メロシアニン色素、4核メロシアニン色素、ロダシアニン色素、コンプレックスシアニン色素、コンプレックスメロシアニン色素、アロポーラー色素、オキソノール色素、ヘミオキソノール色素、スクアリウム色素、クロコニウム色素、アザメチン色素、クマリン色素、アリーリデン色素、アントラキノン色素、トリフェニルメタン色素、アゾ色素、アゾメチン色素、スピロ化合物、メタロセン色素、フルオレノン色素、フルギド色素、ペリレン色素、ペリノン色素、フェナジン色素、フェノチアジン色素、キノン色素、ジフェニルメタン色素、ポリエン色素、アクリジン色素、アクリジノン色素、ジフェニルアミン色素、キナクリドン色素、キノフタロン色素、フェノキサジン色素、フタロペリレン色素、ジケトピロロピロール色素、ジオキサン色素、ポルフィリン色素、クロロフィル色素、フタロシアニン色素、金属錯体色素、縮合芳香族炭素環系色素(ナフタレン誘導体、アントラセン誘導体、フェナントレン誘導体、テトラセン誘導体、ピレン誘導体、ペリレン誘導体、フルオランテン誘導体)が挙げられる。
Any organic dye may be used as the p-type organic semiconductor or the n-type organic semiconductor, but preferably a cyanine dye, a styryl dye, a hemicyanine dye, a merocyanine dye (including zero methine merocyanine (simple merocyanine)), 3 Nuclear merocyanine dye, 4-nuclear merocyanine dye, rhodacyanine dye, complex cyanine dye, complex merocyanine dye, allopolar dye, oxonol dye, hemioxonol dye, squalium dye, croconium dye, azamethine dye, coumarin dye, arylidene dye, anthraquinone dye, tri Phenylmethane dye, azo dye, azomethine dye, spiro compound, metallocene dye, fluorenone dye, fulgide dye, perylene dye, perinone dye, phenazine dye, phenothiazine Dye, quinone dye, diphenylmethane dye, polyene dye, acridine dye, acridinone dye, diphenylamine dye, quinacridone dye, quinophthalone dye, phenoxazine dye, phthaloperylene dye, diketopyrrolopyrrole dye, dioxane dye, porphyrin dye, chlorophyll dye, phthalocyanine dye , Metal complex dyes, condensed aromatic carbocyclic dyes (naphthalene derivatives, anthracene derivatives, phenanthrene derivatives, tetracene derivatives, pyrene derivatives, perylene derivatives, fluoranthene derivatives).
n型有機半導体として、電子輸送性に優れた、フラーレン又はフラーレン誘導体を用いることが特に好ましい。フラーレンとは、フラーレンC60、フラーレンC70、フラーレンC76、フラーレンC78、フラーレンC80、フラーレンC82、フラーレンC84、フラーレンC90、フラーレンC96、フラーレンC240、フラーレン540、ミックスドフラーレン、フラーレンナノチューブを表し、フラーレン誘導体とはこれらに置換基が付加された化合物のことを表す。
It is particularly preferable to use fullerene or fullerene derivatives having excellent electron transport properties as the n-type organic semiconductor. Fullerene means fullerene C60, fullerene C70, fullerene C76, fullerene C78, fullerene C80, fullerene C82, fullerene C84, fullerene C90, fullerene C96, fullerene C240, fullerene 540, mixed fullerene, and fullerene nanotubes. It represents a compound having a substituent added thereto.
フラーレン誘導体の置換基として好ましくは、アルキル基、アリール基、又は複素環基である。アルキル基として更に好ましくは、炭素数1~12までのアルキル基であり、アリール基、及び複素環基として好ましくは、ベンゼン環、ナフタレン環、アントラセン環、フェナントレン環、フルオレン環、トリフェニレン環、ナフタセン環、ビフェニル環、ピロール環、フラン環、チオフェン環、イミダゾール環、オキサゾール環、チアゾール環、ピリジン環、ピラジン環、ピリミジン環、ピリダジン環、インドリジン環、インドール環、ベンゾフラン環、ベンゾチオフェン環、イソベンゾフラン環、ベンズイミダゾール環、イミダゾピリジン環、キノリジン環、キノリン環、フタラジン環、ナフチリジン環、キノキサリン環、キノキサゾリン環、イソキノリン環、カルバゾール環、フェナントリジン環、アクリジン環、フェナントロリン環、チアントレン環、クロメン環、キサンテン環、フェノキサチイン環、フェノチアジン環、またはフェナジン環であり、さらに好ましくは、ベンゼン環、ナフタレン環、アントラセン環、フェナントレン環、ピリジン環、イミダゾール環、オキサゾール環、またはチアゾール環であり、特に好ましくはベンゼン環、ナフタレン環、またはピリジン環である。これらはさらに置換基を有していてもよく、その置換基は可能な限り結合して環を形成してもよい。なお、複数の置換基を有しても良く、それらは同一であっても異なっていても良い。また、複数の置換基は可能な限り結合して環を形成してもよい。
The substituent for the fullerene derivative is preferably an alkyl group, an aryl group, or a heterocyclic group. The alkyl group is more preferably an alkyl group having 1 to 12 carbon atoms, and the aryl group and the heterocyclic group are preferably benzene ring, naphthalene ring, anthracene ring, phenanthrene ring, fluorene ring, triphenylene ring, naphthacene ring. , Biphenyl ring, pyrrole ring, furan ring, thiophene ring, imidazole ring, oxazole ring, thiazole ring, pyridine ring, pyrazine ring, pyrimidine ring, pyridazine ring, indolizine ring, indole ring, benzofuran ring, benzothiophene ring, isobenzofuran Ring, benzimidazole ring, imidazopyridine ring, quinolidine ring, quinoline ring, phthalazine ring, naphthyridine ring, quinoxaline ring, quinoxazoline ring, isoquinoline ring, carbazole ring, phenanthridine ring, acridine ring, phenanthroline , Thianthrene ring, chromene ring, xanthene ring, phenoxathiin ring, phenothiazine ring, or phenazine ring, more preferably a benzene ring, naphthalene ring, anthracene ring, phenanthrene ring, pyridine ring, imidazole ring, oxazole ring, or A thiazole ring, particularly preferably a benzene ring, a naphthalene ring, or a pyridine ring. These may further have a substituent, and the substituents may be bonded as much as possible to form a ring. In addition, you may have a some substituent and they may be the same or different. A plurality of substituents may be combined as much as possible to form a ring.
光電変換層がフラーレン又はフラーレン誘導体を含むことで、フラーレン分子またはフラーレン誘導体分子を経由して、光電変換により発生した電子を画素電極又は対向電極まで早く輸送できる。フラーレン分子またはフラーレン誘導体分子が連なった状態になって電子の経路が形成されていると、電子輸送性が向上して光電変換素子の高速応答性が実現可能となる。このためにはフラーレン又はフラーレン誘導体が光電変換層に40%以上含まれていることが好ましい。もっとも、フラーレン又はフラーレン誘導体が多すぎるとp型有機半導体が少なくなって接合界面が小さくなり励起子解離効率が低下してしまう。
When the photoelectric conversion layer contains fullerene or a fullerene derivative, electrons generated by photoelectric conversion can be quickly transported to the pixel electrode or the counter electrode via the fullerene molecule or the fullerene derivative molecule. When fullerene molecules or fullerene derivative molecules are connected to form an electron path, the electron transport property is improved, and the high-speed response of the photoelectric conversion element can be realized. For this purpose, it is preferable that 40% or more of fullerene or fullerene derivative is contained in the photoelectric conversion layer. However, when there are too many fullerenes or fullerene derivatives, the p-type organic semiconductor is reduced, the junction interface is reduced, and the exciton dissociation efficiency is lowered.
光電変換層において、フラーレン又はフラーレン誘導体と共に混合されるp型有機半導体として、特許第4213832号公報等に記載されたトリアリールアミン化合物を用いると薄膜でも高い吸収および高い量子効率が発現可能になり、特に好ましい。光電変換層内のフラーレン又はフラーレン誘導体の比率が大きすぎると該トリアリールアミン化合物が少なくなって入射光の吸収量が低下する。これにより光電変換効率が減少するので、光電変換層に含まれるフラーレン又はフラーレン誘導体は85%以下の組成であることが好ましい。この構成により、光電変換層において高い感度を発現しつつ、可視光全域でd2を1.0~1.2とすることが出来る。
In the photoelectric conversion layer, as a p-type organic semiconductor mixed with fullerene or a fullerene derivative, when a triarylamine compound described in Japanese Patent No. 4213832 is used, high absorption and high quantum efficiency can be expressed even in a thin film, Particularly preferred. If the ratio of fullerene or fullerene derivative in the photoelectric conversion layer is too large, the amount of the triarylamine compound is reduced and the amount of incident light absorbed is reduced. As a result, the photoelectric conversion efficiency is reduced, so that the fullerene or fullerene derivative contained in the photoelectric conversion layer preferably has a composition of 85% or less. With this configuration, d 2 can be set to 1.0 to 1.2 over the entire visible light range while exhibiting high sensitivity in the photoelectric conversion layer.
保護膜18は、特に、光電変換膜が有機材料を含むものである場合、光電変換層を水分子、酸素などの劣化因子から保護する機能を担うものである。また、保護膜18は、撮像素子10の各製造工程において、有機溶媒等の溶液やプラズマなどに含まれる光電変換層の性能を劣化させる因子の浸入を阻止して光電変換層を保護する機能を担う。また、撮像素子10の製造後に、水分子、酸素などの光電変換層の性能を劣化させる因子の浸入を阻止して、長期間の保存、および長期の使用にわたって、光電変換層の性能劣化を防止する。また、入射光(可視光)は、保護膜18を通じて光電変換膜14に到達する。このため、保護膜18は、光電変換素子17で検知する波長の光、可視光に対して透明である。保護膜18は、光透過率が60%以上であることが好ましく、より好ましくは80%以上、より好ましくは90%以上であり、さらには95%以上であることがより好ましい。
The protective film 18 has a function of protecting the photoelectric conversion layer from deterioration factors such as water molecules and oxygen, particularly when the photoelectric conversion film includes an organic material. The protective film 18 has a function of protecting the photoelectric conversion layer by preventing intrusion of a factor that degrades the performance of the photoelectric conversion layer contained in a solution such as an organic solvent or plasma in each manufacturing process of the image sensor 10. Bear. In addition, after the image pickup device 10 is manufactured, intrusion of factors such as water molecules and oxygen that degrade the performance of the photoelectric conversion layer is prevented to prevent the performance deterioration of the photoelectric conversion layer over a long period of storage and long-term use. To do. Further, incident light (visible light) reaches the photoelectric conversion film 14 through the protective film 18. For this reason, the protective film 18 is transparent to light having a wavelength detected by the photoelectric conversion element 17 and visible light. The protective film 18 preferably has a light transmittance of 60% or more, more preferably 80% or more, more preferably 90% or more, and even more preferably 95% or more.
保護膜の厚みは、概ね50~1000nmであるが、後記条件を満たす範囲で決定される。但し、保護膜18の厚さが50nmを下回るとバリア性の低下や、カラーフィルタの現像液に対する耐性が低下する虞がある。一方、保護膜18の膜厚が厚いと、後述するように混色の増加につながるため、保護膜18は薄い方が好ましい。
The thickness of the protective film is approximately 50 to 1000 nm, but is determined within a range that satisfies the conditions described later. However, when the thickness of the protective film 18 is less than 50 nm, there is a possibility that the barrier property is lowered and the resistance of the color filter to the developer is lowered. On the other hand, a thick protective film 18 leads to an increase in color mixture as will be described later. Therefore, the protective film 18 is preferably thin.
保護膜は、特には、気相成膜した無機材料膜が好ましい。無機材料の方が有機材料に比べて薄膜でも保護性能の高い膜を得られやすい。気相成膜法は他の成膜法に比べ緻密な膜が得られるため、薄膜でも高い保護性能が得られる。気相成膜法の中でも特にCVD法は緻密な膜が得られるため、好ましい。また、成膜速度が速いため、製造に適している。CVD法の中でもALCVD法は特に緻密な膜が得られるため、保護膜の薄膜化には非常に適している。
The protective film is particularly preferably an inorganic material film formed by vapor phase deposition. It is easier to obtain a film having a higher protection performance with an inorganic material than with an organic material even with a thin film. The vapor deposition method can provide a dense film as compared with other film formation methods, and thus high protection performance can be obtained even with a thin film. Among the vapor deposition methods, the CVD method is particularly preferable because a dense film can be obtained. Further, since the film forming speed is high, it is suitable for manufacturing. Among the CVD methods, the ALCVD method is particularly suitable for reducing the thickness of the protective film because a particularly dense film can be obtained.
無機材料の中でも、酸化アルミニウム(AlOx)、酸化珪素(SiOx)、窒化珪素(SiNx)、酸化窒化珪素(SiON)がほぼ性能および光路長低減の観点から好ましい。特にCVD法で成膜したSiONは成膜条件を変えてOとNの比を調整することで屈折率と保護性能を変えることが出来、短い光路長で高い保護性能が得られる。
またALCVD法で成膜したAlOxは100nm以下と他の成膜法より一桁近く小さい膜厚でも高い保護性能を得ることが出来る。
したがって、例えばALCVD法で成膜した100nm以下のAlOxとCVD法で成膜した100~500nmのSiONの積層膜は光路長、保護性能の観点から非常に好ましい。 Among the inorganic materials, aluminum oxide (AlOx), silicon oxide (SiOx), silicon nitride (SiNx), and silicon oxynitride (SiON) are preferable from the viewpoints of performance and optical path length reduction. In particular, SiON formed by CVD can change the refractive index and protection performance by changing the film formation conditions and adjusting the ratio of O and N, and high protection performance can be obtained with a short optical path length.
Further, AlOx formed by the ALCVD method can obtain high protection performance even with a film thickness of 100 nm or less, which is almost an order of magnitude smaller than other film forming methods.
Therefore, for example, a laminated film of 100 nm or less of AlOx formed by ALCVD and 100 to 500 nm of SiON formed by CVD is very preferable from the viewpoint of optical path length and protection performance.
またALCVD法で成膜したAlOxは100nm以下と他の成膜法より一桁近く小さい膜厚でも高い保護性能を得ることが出来る。
したがって、例えばALCVD法で成膜した100nm以下のAlOxとCVD法で成膜した100~500nmのSiONの積層膜は光路長、保護性能の観点から非常に好ましい。 Among the inorganic materials, aluminum oxide (AlOx), silicon oxide (SiOx), silicon nitride (SiNx), and silicon oxynitride (SiON) are preferable from the viewpoints of performance and optical path length reduction. In particular, SiON formed by CVD can change the refractive index and protection performance by changing the film formation conditions and adjusting the ratio of O and N, and high protection performance can be obtained with a short optical path length.
Further, AlOx formed by the ALCVD method can obtain high protection performance even with a film thickness of 100 nm or less, which is almost an order of magnitude smaller than other film forming methods.
Therefore, for example, a laminated film of 100 nm or less of AlOx formed by ALCVD and 100 to 500 nm of SiON formed by CVD is very preferable from the viewpoint of optical path length and protection performance.
保護膜とカラーフィルタの間に反射防止層やカラーフィルタ密着強化層などの機能層を有していても良い。ただし、これらの層を用いる場合にも、後述するようにカラーフィルタ層の底面から光電変換膜の上面までの光路長が1.2μm以下となるように薄膜を用いることが必要である。
A functional layer such as an antireflection layer or a color filter adhesion enhancing layer may be provided between the protective film and the color filter. However, even when these layers are used, it is necessary to use a thin film so that the optical path length from the bottom surface of the color filter layer to the top surface of the photoelectric conversion film is 1.2 μm or less, as will be described later.
なお、本実施形態においては、光電変換膜14と画素電極との間に、光電変換素子の機能を向上させるための機能層、具体的には、暗電流低減のための電荷ブロッキング層を備えている。
本発明の撮像素子においては、光電変換膜の膜厚を薄くしているために、ショートやリークによる暗電流増大の危険性が高いので、電荷ブロッキング層を備えることによる暗電流抑制の効果が高い。 In the present embodiment, a functional layer for improving the function of the photoelectric conversion element, specifically, a charge blocking layer for reducing dark current is provided between thephotoelectric conversion film 14 and the pixel electrode. Yes.
In the imaging device of the present invention, since the photoelectric conversion film is thin, there is a high risk of dark current increase due to a short circuit or a leak, so that the dark current suppression effect by providing the charge blocking layer is high. .
本発明の撮像素子においては、光電変換膜の膜厚を薄くしているために、ショートやリークによる暗電流増大の危険性が高いので、電荷ブロッキング層を備えることによる暗電流抑制の効果が高い。 In the present embodiment, a functional layer for improving the function of the photoelectric conversion element, specifically, a charge blocking layer for reducing dark current is provided between the
In the imaging device of the present invention, since the photoelectric conversion film is thin, there is a high risk of dark current increase due to a short circuit or a leak, so that the dark current suppression effect by providing the charge blocking layer is high. .
カラーフィルタ層CFは、各フィルタ21が保護膜18上の各画素電極12と対向する位置となるように配置形成されている。
カラーフィルタ層CFは、図3に示すようにR、G、Bのそれぞれ異なる波長の光を透過するカラーフィルタおよび可視光全域を透過するWフィルタを有する。R,G,Bの各フィルタは、赤/青/緑色の顔料、もしくは染料の入った有機材料により形成される。 The color filter layer CF is disposed and formed so that each filter 21 is located at a position facing eachpixel electrode 12 on the protective film 18.
As shown in FIG. 3, the color filter layer CF includes a color filter that transmits light of different wavelengths of R, G, and B and a W filter that transmits the entire visible light. Each of the R, G, and B filters is formed of an organic material containing a red / blue / green pigment or dye.
カラーフィルタ層CFは、図3に示すようにR、G、Bのそれぞれ異なる波長の光を透過するカラーフィルタおよび可視光全域を透過するWフィルタを有する。R,G,Bの各フィルタは、赤/青/緑色の顔料、もしくは染料の入った有機材料により形成される。 The color filter layer CF is disposed and formed so that each filter 21 is located at a position facing each
As shown in FIG. 3, the color filter layer CF includes a color filter that transmits light of different wavelengths of R, G, and B and a W filter that transmits the entire visible light. Each of the R, G, and B filters is formed of an organic material containing a red / blue / green pigment or dye.
各カラーフィルタは一般的にはカラーレジストを紫外線にて露光・現像することにより形成する。カラーレジストは各色の顔料、光硬化樹脂、粘度調整剤等より構成されるが、露光、現像してパターン形成後のカラーフィルタの屈折率は主成分となる顔料と光硬化樹脂とで決まる。そのため、図1に示したように、カラーフィルタの屈折率はWRGBの各色で異なり、また入射光の波長によっても異なる。
図1は、WRGBフィルタの一例を示すものであるが、カラーフィルタ層の各色のフィルタはいずれも光硬化樹脂を用いるのが一般的であるため、各色毎の屈折率差自体は図1と同様に0~0.4程度である。 Each color filter is generally formed by exposing and developing a color resist with ultraviolet rays. The color resist is composed of pigments of various colors, a photo-curing resin, a viscosity adjusting agent, and the like. The refractive index of the color filter after pattern formation by exposure and development is determined by the main component pigment and the photo-curing resin. Therefore, as shown in FIG. 1, the refractive index of the color filter differs for each color of WRGB, and also differs depending on the wavelength of incident light.
FIG. 1 shows an example of a WRGB filter. However, since each color filter of a color filter layer generally uses a photo-curing resin, the refractive index difference for each color itself is the same as that in FIG. 0 to 0.4.
図1は、WRGBフィルタの一例を示すものであるが、カラーフィルタ層の各色のフィルタはいずれも光硬化樹脂を用いるのが一般的であるため、各色毎の屈折率差自体は図1と同様に0~0.4程度である。 Each color filter is generally formed by exposing and developing a color resist with ultraviolet rays. The color resist is composed of pigments of various colors, a photo-curing resin, a viscosity adjusting agent, and the like. The refractive index of the color filter after pattern formation by exposure and development is determined by the main component pigment and the photo-curing resin. Therefore, as shown in FIG. 1, the refractive index of the color filter differs for each color of WRGB, and also differs depending on the wavelength of incident light.
FIG. 1 shows an example of a WRGB filter. However, since each color filter of a color filter layer generally uses a photo-curing resin, the refractive index difference for each color itself is the same as that in FIG. 0 to 0.4.
本発明では、カラーフィルタ層CFの底面から光電変換膜14までの光路長d1が1.2μm以下であり、光電変換膜14の厚みの光路長d2が1.4μm以下であることを特徴とする。
In the present invention, the optical path length d 1 from the bottom surface of the color filter layer CF to the photoelectric conversion film 14 is 1.2 μm or less, and the optical path length d 2 of the thickness of the photoelectric conversion film 14 is 1.4 μm or less. And
本実施形態においては、カラーフィルタ層CFと光電変換膜14との間に保護膜18および対向電極16を備えたものとしたが、さらに他の層が入っていてもよい。なお、光路長は、空間的な距離と屈折率の積で表わされ、ここで、光路長d1は複数の異なる屈折率の層を有するため、各層の光路長の和で表わされる。例えば、図11に示す構成において、保護膜18の厚みがt1、屈折率がn1、対向電極16の厚みがt2、屈折率がn2であるとき、光路長d1=n1・t1+n2・t2である。
In the present embodiment, the protective film 18 and the counter electrode 16 are provided between the color filter layer CF and the photoelectric conversion film 14, but other layers may be included. The optical path length is represented by the product of the spatial distance and refractive index, wherein the optical path length d 1 is to have a layer of a plurality of different refractive index, it is represented by the sum of the optical path length of each layer. For example, in the configuration shown in FIG. 11, when the thickness of the protective film 18 is t 1 , the refractive index is n 1 , the thickness of the counter electrode 16 is t 2 , and the refractive index is n 2 , the optical path length d 1 = n 1. t 1 + n 2 · t 2 .
また、光電変換膜14の厚みの光路長、すなわち光電変換膜14の上面から底面までの光路長d2は、その厚みt3、屈折率n3とからd2=n3・t3で表わされる。
The optical path length of the thickness of the photoelectric conversion film 14, that is, the optical path length d 2 from the top surface to the bottom surface of the photoelectric conversion film 14 is expressed by d 2 = n 3 · t 3 from the thickness t 3 and the refractive index n 3. It is.
本発明者は、種々検討を重ね、少なくとも上記範囲であれば混色率を十分に低減できることを見出した。上記範囲が好ましいことを見出すに至った検討について以下に説明する。
The present inventor has conducted various studies and found that the color mixing ratio can be sufficiently reduced at least within the above range. The investigation that has led to the finding that the above range is preferable will be described below.
レジスト中に色素等を混入して作製される一般的なカラーフィルタにおいては、WとR、G、Bとの屈折率差は、図1に示すように、いずれも0.4程度以下である。また、屈折率差が十分小さければほとんど混色は発生しない。本発明者らの検討によれば、屈折率差が0.1未満であれば問題となるほどの混色は生じなかった。そこで、W画素と他の画素との屈折率差は0.1~0.4程度を想定して検討した。また、入射光はフィルタ上方から垂直に入射する場合について検討した。
In a general color filter manufactured by mixing a dye or the like in a resist, the refractive index difference between W and R, G, and B is about 0.4 or less as shown in FIG. . If the difference in refractive index is sufficiently small, almost no color mixing occurs. According to the study by the present inventors, if the difference in refractive index is less than 0.1, color mixing that causes a problem did not occur. In view of this, the difference in refractive index between the W pixel and the other pixels was assumed to be about 0.1 to 0.4. In addition, the case where incident light enters vertically from above the filter was studied.
Wフィルタを透過した光の隣接画素への浸みだしは、フィルタの底面から離れるほど広がると考え、フィルタの底面から光電変換膜底面までの距離について検討を行った。
図11に示す構成の撮像素子において、隣接する2つの異なる色のフィルタ間の屈折率差が0.1、0.4であるとき、屈折率の低いフィルタから屈折率の高いフィルタ側の光電変換部に入射する光による混色率について、d1、d2を変化させて検討を行った。なお、ここでは画素サイズは3μmとした。 Considering that the penetration of light transmitted through the W filter into adjacent pixels spreads away from the bottom surface of the filter, the distance from the bottom surface of the filter to the bottom surface of the photoelectric conversion film was examined.
In the imaging device having the configuration shown in FIG. 11, when the refractive index difference between two adjacent filters of different colors is 0.1 and 0.4, the photoelectric conversion from the low refractive index filter to the high refractive index filter side is performed. The color mixing ratio due to the light incident on the part was examined by changing d 1 and d 2 . Here, the pixel size is 3 μm.
図11に示す構成の撮像素子において、隣接する2つの異なる色のフィルタ間の屈折率差が0.1、0.4であるとき、屈折率の低いフィルタから屈折率の高いフィルタ側の光電変換部に入射する光による混色率について、d1、d2を変化させて検討を行った。なお、ここでは画素サイズは3μmとした。 Considering that the penetration of light transmitted through the W filter into adjacent pixels spreads away from the bottom surface of the filter, the distance from the bottom surface of the filter to the bottom surface of the photoelectric conversion film was examined.
In the imaging device having the configuration shown in FIG. 11, when the refractive index difference between two adjacent filters of different colors is 0.1 and 0.4, the photoelectric conversion from the low refractive index filter to the high refractive index filter side is performed. The color mixing ratio due to the light incident on the part was examined by changing d 1 and d 2 . Here, the pixel size is 3 μm.
屈折率差Δn=0.4としては、R光(650nm)を入射したときのW画素からB画素への光の漏れ出しを検討した。BフィルタのR光透過率はほぼ0であるため、B画素の信号は全て漏れ込みによるものと考えられる。そこでB画素で発生した信号電荷を画素サイズ(3μm)で割ったものを混色率としてプロットを行った。
Δn=0.1としては、B光(450nm)を入射したときのW画素からR画素への光の漏れ出しを検討した。RフィルタのB光透過率はほぼ0であるため、R画素の信号は全て漏れ込みによるものと考えられる。そこでR画素で発生した信号電荷を画素サイズ(3μm)で割ったものを混色率としてプロットを行った。 Regarding the refractive index difference Δn = 0.4, the leakage of light from the W pixel to the B pixel when R light (650 nm) was incident was examined. Since the R light transmittance of the B filter is almost 0, it is considered that all signals of the B pixel are caused by leakage. Therefore, the signal charge generated in the B pixel divided by the pixel size (3 μm) was plotted as a color mixture ratio.
As Δn = 0.1, the leakage of light from the W pixel to the R pixel when B light (450 nm) was incident was examined. Since the B light transmittance of the R filter is almost 0, it is considered that all signals of the R pixel are caused by leakage. Therefore, the signal mixture generated by dividing the signal charge generated in the R pixel by the pixel size (3 μm) was plotted as the color mixture ratio.
Δn=0.1としては、B光(450nm)を入射したときのW画素からR画素への光の漏れ出しを検討した。RフィルタのB光透過率はほぼ0であるため、R画素の信号は全て漏れ込みによるものと考えられる。そこでR画素で発生した信号電荷を画素サイズ(3μm)で割ったものを混色率としてプロットを行った。 Regarding the refractive index difference Δn = 0.4, the leakage of light from the W pixel to the B pixel when R light (650 nm) was incident was examined. Since the R light transmittance of the B filter is almost 0, it is considered that all signals of the B pixel are caused by leakage. Therefore, the signal charge generated in the B pixel divided by the pixel size (3 μm) was plotted as a color mixture ratio.
As Δn = 0.1, the leakage of light from the W pixel to the R pixel when B light (450 nm) was incident was examined. Since the B light transmittance of the R filter is almost 0, it is considered that all signals of the R pixel are caused by leakage. Therefore, the signal mixture generated by dividing the signal charge generated in the R pixel by the pixel size (3 μm) was plotted as the color mixture ratio.
図12は、d2を1.4μmとしたときの混色率のd1依存性を示すグラフである。図12に示すように、混色率はd1が1.2μm以下ではほとんど変化しないが、1.2μmを超えると急激に増加した。
FIG. 12 is a graph showing the dependence of the color mixture ratio on d 1 when d 2 is 1.4 μm. As shown in FIG. 12, the color mixture rate hardly changed when d 1 was 1.2 μm or less, but rapidly increased when d 1 exceeded 1.2 μm.
また、図13は、d1を1.2μmとしたときの混色率のd2依存性を示すグラフである。図13に示すように、混色率はd2が1.4μm以下ではほとんど変化しないが、1.4μmを超えると急激に増加した。
FIG. 13 is a graph showing the d 2 dependency of the color mixture rate when d 1 is 1.2 μm. As shown in FIG. 13, the color mixing ratio is hardly changed by d 2 is 1.4 [mu] m or less, and rapidly increase exceeds 1.4 [mu] m.
なお、d1=1.2μm、d2=1.4μmとし、画素サイズを変更して混色率の変化を調べたところ、図14に示すように、混色率は画素サイズにはあまり依存しなかった。このことから光の浸みだしが、画素境界付近の僅かな領域のみで発生していることが明らかとなった。
Note that, when d 1 = 1.2 μm and d 2 = 1.4 μm, and the change in the color mixture rate was examined by changing the pixel size, as shown in FIG. 14, the color mixture rate did not depend much on the pixel size. It was. From this, it became clear that the soaking of light occurred only in a small area near the pixel boundary.
以上の結果より、固体撮像素子中での光の漏れ出しは図15のようであることが明らかとなった。図15は、固体撮像素子中において、Wフィルタを透過した光の隣接画素へ漏れ出しを模式的に示す図である。図15おいて厚みは実際の膜厚ではなく光路長で示している。Wカラーフィルタを透過した光は、Wカラーフィルタと隣接するカラーフィルタとの屈折率差に起因して保護膜中および光電変換膜中で徐々に隣接画素に漏れ出していく。ただし、漏れ出しは深さ方向に対してリニアに増加するのではなく、カラーフィルタに近い上部では漏れ出し領域は狭く、深くなるにつれて漏れ出し領域が急激に広がるような漏れ出し方である。
From the above results, it was clarified that light leakage in the solid-state imaging device was as shown in FIG. FIG. 15 is a diagram schematically illustrating leakage of light transmitted through the W filter to adjacent pixels in the solid-state imaging device. In FIG. 15, the thickness is indicated by the optical path length, not the actual film thickness. The light transmitted through the W color filter gradually leaks to the adjacent pixels in the protective film and the photoelectric conversion film due to the difference in refractive index between the W color filter and the adjacent color filter. However, the leakage does not increase linearly with respect to the depth direction, but the leakage region is narrow in the upper part near the color filter, and the leakage region spreads rapidly as the depth increases.
このようにして漏れ出した光のうち、隣接画素の光電変換層で吸収される光が混色の原因となる。ただし、光は光電変換層に吸収されながら深さ方向に浸透するため、仮に漏れ出し領域が同じだとすると、光電変換層上部では多くの信号電荷が発生し、光電変換層下部で発生する信号電荷は少ない。すなわち、光電変換層上部の漏れ出し領域を狭めることが重要である。これはd1の値が大きいと、光電変換層の上部における漏れだし領域が大きくなり、混色が飛躍的に増加することを示しており、図12に示したようにd1を1.2μm以下とすることが混色低減に必要である。
Of the light leaked in this way, the light absorbed by the photoelectric conversion layer of the adjacent pixel causes color mixing. However, since light penetrates in the depth direction while being absorbed by the photoelectric conversion layer, if the leakage region is the same, a large amount of signal charge is generated at the upper part of the photoelectric conversion layer, and the signal charge generated at the lower part of the photoelectric conversion layer is Few. That is, it is important to narrow the leak region above the photoelectric conversion layer. This indicates that when the value of d 1 is large, the leakage area at the upper part of the photoelectric conversion layer becomes large and the color mixture increases drastically. As shown in FIG. 12, d 1 is 1.2 μm or less. It is necessary to reduce color mixing.
一方、光電変換層下部については、d2が大きくなるほど漏れ出し領域の面積が非線形に大きくなる。図13に示したように、d2が1.4μmを越えると爆発的に混色が増加することから、d2を1.4μm以下とすることが必要である。
On the other hand, regarding the lower part of the photoelectric conversion layer, the area of the leakage region increases nonlinearly as d 2 increases. As shown in FIG. 13, when d 2 exceeds 1.4 μm, the color mixture increases explosively, so d 2 needs to be 1.4 μm or less.
すなわち、本発明は、半導体回路基板上に全画素共通膜状の光電変換膜を備えた積層型撮像素子において、Wフィルタを含むカラーフィルタ層を備え、カラーフィルタ層底面から光電変換膜の上面までの光路長d1を1.2μm以下、光電変換膜の厚み光路長d2を1.4μm以下とした。これにより、Wフィルタを備えた場合に生じ得る混色を抑制してS/N低下を防止することができ、Wフィルタを備えることによる高感度化の効果を十分に得ることできる。
That is, according to the present invention, in a stacked imaging device including a photoelectric conversion film in a film shape common to all pixels on a semiconductor circuit substrate, a color filter layer including a W filter is provided, from the bottom surface of the color filter layer to the upper surface of the photoelectric conversion film. of 1.2μm below the optical path length d 1, and the thickness optical path length d 2 of the photoelectric conversion layer and below 1.4 [mu] m. As a result, color mixing that may occur when the W filter is provided can be suppressed to prevent S / N reduction, and the effect of increasing sensitivity by providing the W filter can be sufficiently obtained.
更に、フィルタ間の屈折率差Δnが大きくなることで、光の漏れ出し領域が大きくなることが分かった。図16および図17はそれぞれ屈折率差Δnが0.2、0、4の場合の、Wフィルタを透過した光の隣接画素へ漏れ出しを模式的に示す図である。図16および図17に示すように、屈折率差Δnが大きくなると、漏れ出し領域が大きくなる。図16および図17より、屈折率差Δnが大きくなると、漏れ出し領域が急激に大きくなるような広がり方である。
Furthermore, it has been found that the light leakage area increases as the refractive index difference Δn between the filters increases. 16 and 17 are diagrams schematically showing leakage of light transmitted through the W filter to adjacent pixels when the refractive index difference Δn is 0.2, 0, and 4, respectively. As shown in FIGS. 16 and 17, the leakage area increases as the refractive index difference Δn increases. From FIG. 16 and FIG. 17, when the refractive index difference Δn is increased, the leakage region is spread so as to increase rapidly.
屈折率差Δnと漏れ出し領域に上記のような相関があることを考えると、屈折率差Δnに応じてd1、d2に適切な範囲が存在することが考えられる。ただし、図16および図17に示すように漏れ出し領域が深さ方向に行くほど広がる複雑な形状をしている上に、光電変換膜中で光が吸収されて光電変換部下部にはわずかな光しか到達しないなど複雑な現象であるため、混色を制御するための屈折率差Δnとd1、d2の適切な相関は一意には求まらない。
Considering that there is the above correlation between the refractive index difference Δn and the leakage region, it is conceivable that appropriate ranges exist for d 1 and d 2 according to the refractive index difference Δn. However, as shown in FIGS. 16 and 17, the leakage region has a complicated shape that expands as it goes in the depth direction, and light is absorbed in the photoelectric conversion film so that there is a slight amount below the photoelectric conversion unit. Since this is a complicated phenomenon such as the arrival of only light, an appropriate correlation between the refractive index difference Δn and d 1 and d 2 for controlling color mixing cannot be uniquely determined.
そこで発明者はまず図18に示すように、d1、d2および屈折率差Δnを変化させた場合の混色率のデータを取得した。図18においては、d1=1.2μmの場合の、Δn=0.1、0.2、0.3、0.4と変化させた場合についてのみ示しているが、d1を0.2、0.6μmとした場合についても同様にデータを取得している。しかしながら、データ値が重なり視認性が低下するため、図18には示していない。次に得られたデータに対してd1、d2および屈折率差Δnの間に適当な関係式(例えば、Δn × (d1+d2))を予想し、その値に対して混色率との関係をプロットすることで、d1が1.2μm以下、d2が1.4μm以下の条件下において、更に効果的に混色を抑圧できる条件を探索した。この結果、図19に示すようにΔn × (d1+d2)2を2.0以下とすることで混色がより効果的に抑圧できることが分かった。
Therefore, the inventor first obtained data of the color mixing ratio when d 1 , d 2 and the refractive index difference Δn were changed as shown in FIG. FIG. 18 shows only the case where Δn = 0.1, 0.2, 0.3, 0.4 when d 1 = 1.2 μm, but d1 is 0.2, Similarly, data is acquired for the case of 0.6 μm. However, since data values overlap and visibility decreases, it is not shown in FIG. Next, an appropriate relational expression (for example, Δn × (d 1 + d 2 )) is predicted between d 1 , d 2 and the refractive index difference Δn for the obtained data, and the color mixing rate and By plotting the relationship, a condition under which color mixing can be more effectively suppressed under conditions where d 1 is 1.2 μm or less and d 2 is 1.4 μm or less was searched. As a result, it was found that color mixing can be more effectively suppressed by setting Δn × (d 1 + d 2 ) 2 to 2.0 or less as shown in FIG.
図19は図18の結果をもとに、d1が1.2μm以下、d2が1.4μm以下の場合について、横軸にΔn × (d1+d2)2を、縦軸に混色率をプロットしたグラフである。図19に外挿線を示す通り、Δn × (d1+d2)2が2.0を境に傾きが大きく変化し、Δn × (d1+d2)2が2.0以上となると、2.0未満の場合に比べて混色の増加が顕著になることを見出した。すなわち、
Δn × (d1+d2)2< 2.0
とすることにより混色をより効果的に抑圧できることを見出した。 FIG. 19 is based on the result of FIG. 18, and in the case where d 1 is 1.2 μm or less and d 2 is 1.4 μm or less, Δn × (d 1 + d 2 ) 2 is plotted on the horizontal axis and the color mixing ratio is plotted on the vertical axis. Is a graph in which is plotted. As shown in FIG. 19, when Δn × (d 1 + d 2 ) 2 changes greatly from 2.0 as a boundary, and Δn × (d 1 + d 2 ) 2 becomes 2.0 or more, 2 It has been found that the increase in color mixture becomes remarkable as compared with the case of less than 0.0. That is,
Δn × (d 1 + d 2 ) 2 <2.0
It was found that color mixing can be suppressed more effectively.
Δn × (d1+d2)2< 2.0
とすることにより混色をより効果的に抑圧できることを見出した。 FIG. 19 is based on the result of FIG. 18, and in the case where d 1 is 1.2 μm or less and d 2 is 1.4 μm or less, Δn × (d 1 + d 2 ) 2 is plotted on the horizontal axis and the color mixing ratio is plotted on the vertical axis. Is a graph in which is plotted. As shown in FIG. 19, when Δn × (d 1 + d 2 ) 2 changes greatly from 2.0 as a boundary, and Δn × (d 1 + d 2 ) 2 becomes 2.0 or more, 2 It has been found that the increase in color mixture becomes remarkable as compared with the case of less than 0.0. That is,
Δn × (d 1 + d 2 ) 2 <2.0
It was found that color mixing can be suppressed more effectively.
なお、上記実施形態においては、カラーフィルタの配列をRGBのベイヤー配列のうちのGの1つをWに置き換えた配列としているが、カラーフィルタ配列は上記配列に限定されず、任意に変更可能である。また、R、G、Bに代えて補色型のカラーフィルタを備えていてもよく、イエロー、マゼンダ、シアン、白の4種のカラーフィルタを備えたカラーフィルタ層を備えてもよい。その場合でも、通常は白が最も屈折率が小さいことから、同様に白画素から他の画素への光の浸みだしが生じるため、上記実施形態と同様に光路長d1、d2を制御することにより光の浸み出しによる影響を抑制し、高いS/Nの画像を取得することができる。
In the above embodiment, the color filter array is an array in which one of G of RGB Bayer arrays is replaced with W. However, the color filter array is not limited to the above array and can be arbitrarily changed. is there. Further, instead of R, G, and B, a complementary color filter may be provided, or a color filter layer including four types of color filters of yellow, magenta, cyan, and white may be provided. Even in that case, since white generally has the smallest refractive index, light oozes out from the white pixel to other pixels in the same manner, so that the optical path lengths d 1 and d 2 are controlled as in the above embodiment. As a result, the influence of light oozing can be suppressed, and a high S / N image can be acquired.
図20は、各画素部20における信号読出回路11および該回路部11と光電変換部17との関係を示す回路図である。図20に示すように、信号読出回路11には、出力トランジスタ32と、リセットトランジスタ33と、選択トランジスタ34が形成されている。そして、出力トランジスタ32、リセットトランジスタ33、選択トランジスタ34は、それぞれnチャネルのMOSトランジスタで構成されている。光電変換部17と出力トランジスタ32のゲートが電気的につながっており、このノードをフローティングディフュージョンFD(以下、単にFDという)と称する。図11において、信号読出回路11は1つの領域として示されているが、実際には、この領域に上述の各要素が形成されている。
FIG. 20 is a circuit diagram showing the signal readout circuit 11 in each pixel unit 20 and the relationship between the circuit unit 11 and the photoelectric conversion unit 17. As shown in FIG. 20, in the signal readout circuit 11, an output transistor 32, a reset transistor 33, and a selection transistor 34 are formed. The output transistor 32, the reset transistor 33, and the selection transistor 34 are each composed of an n-channel MOS transistor. The photoelectric conversion unit 17 and the gate of the output transistor 32 are electrically connected, and this node is referred to as a floating diffusion FD (hereinafter simply referred to as FD). In FIG. 11, the signal readout circuit 11 is shown as one region, but in reality, the above-described elements are formed in this region.
本実施形態の画素部20においては、光電変換膜14で発生した電荷のうち正孔が画素電極12に移動し、電子が対向電極16に移動するように、画素電極12に対してバイアス電圧が印加される。光電変換膜14が十分に高い感度を発現するように、バイアス電圧としては、読み出し回路の電源電圧Vdd(図20において出力トランジスタのドレインに供給されている電圧、たとえば3V)よりも高い電圧(5~20V程度、たとえば10V)を用いることが望ましい。
In the pixel unit 20 of the present embodiment, a bias voltage is applied to the pixel electrode 12 such that holes out of the charges generated in the photoelectric conversion film 14 move to the pixel electrode 12 and electrons move to the counter electrode 16. Applied. As a bias voltage, a voltage (5 V) higher than the power supply voltage Vdd of the readout circuit (voltage supplied to the drain of the output transistor in FIG. 20, for example, 3 V) so that the photoelectric conversion film 14 exhibits sufficiently high sensitivity. It is desirable to use about 20V, for example 10V).
FDは、画素電極12と電気的につながったn形不純物領域を含むノードである。FDは光電変換部17や各トランジスタの寄生容量等に起因して容量を持つ。画素電極12に捕集された電荷の量に応じてFDの電位が変化するため、FDは電荷蓄積部として機能する。
FD is a node including an n-type impurity region electrically connected to the pixel electrode 12. The FD has a capacitance due to the parasitic capacitance of the photoelectric conversion unit 17 and each transistor. Since the potential of the FD changes according to the amount of charges collected by the pixel electrode 12, the FD functions as a charge storage unit.
出力トランジスタ32は、FDに蓄積された電荷信号を電圧信号に変換して信号線に出力するものである。出力トランジスタ32のゲート端子はFDに電気的に接続され、ドレイン端子は固体撮像素子の電源電圧Vddが接続されている。また、出力トランジスタ32のソース端子は選択トランジスタ34のドレイン端子に接続されている。本実施形態における画素部20は、FDと光電変換部17の画素電極12と出力トランジスタ32のゲート端子とが電気的に直接接続された、いわゆる3トランジスタの構成の回路である。
The output transistor 32 converts the charge signal accumulated in the FD into a voltage signal and outputs it to the signal line. The gate terminal of the output transistor 32 is electrically connected to the FD, and the drain terminal is connected to the power supply voltage Vdd of the solid-state imaging device. The source terminal of the output transistor 32 is connected to the drain terminal of the selection transistor 34. The pixel unit 20 in the present embodiment is a circuit having a so-called three-transistor configuration in which the FD, the pixel electrode 12 of the photoelectric conversion unit 17, and the gate terminal of the output transistor 32 are electrically connected directly.
リセットトランジスタ33は、FDの電位を基準電位にリセットするものである。リセットトランジスタ33のドレイン端子にはFDが電気的に接続され、ソース端子にはリセット電源が接続され、電圧RDが供給されている。リセットトランジスタ33のゲート端子に印加されるリセットパルスRSがハイレベルになると、リセットトランジスタ33がオンし、リセットトランジスタ33のソースからドレインに電子が注入される。そして、この電子の注入によってFDの電位が降下してFDの電位が基準電位にリセットされる。選択トランジスタ34は、そのソース端子が信号線に接続されるものであり、各画素の出力トランジスタ32から出力される信号を列ごとに設けられた信号線に選択的に出力するためのものである。選択トランジスタ34のゲート端子に印加される選択パルスRWがハイレベルになると、選択トランジスタ34はオンし、これにより各画素の出力トランジスタ32から出力された信号が信号線に出力される。
The reset transistor 33 resets the potential of the FD to the reference potential. The FD is electrically connected to the drain terminal of the reset transistor 33, the reset power source is connected to the source terminal, and the voltage RD is supplied. When the reset pulse RS applied to the gate terminal of the reset transistor 33 becomes high level, the reset transistor 33 is turned on, and electrons are injected from the source to the drain of the reset transistor 33. Then, due to the injection of electrons, the potential of the FD drops and the potential of the FD is reset to the reference potential. The selection transistor 34 has a source terminal connected to the signal line, and selectively outputs a signal output from the output transistor 32 of each pixel to a signal line provided for each column. . When the selection pulse RW applied to the gate terminal of the selection transistor 34 becomes a high level, the selection transistor 34 is turned on, whereby a signal output from the output transistor 32 of each pixel is output to the signal line.
なお、上記実施形態の固体撮像素子においては、信号読出回路11をリセットトランジスタ33、出力トランジスタ32および選択トランジスタ34をnチャネルMOSトランジスタから構成し、画素電極12によって正孔を捕集するようにしたが、これに限らず、リセットトランジスタ33、出力トランジスタ32および選択トランジスタ34をpチャネルMOSトランジスタから構成するようにし、画素電極12で電子を捕集し、その電子の量に応じた電荷信号を、pチャネルMOSトランジスタで構成された信号読出し回路11で読み出すようにしてもよい。
In the solid-state imaging device of the above-described embodiment, the signal readout circuit 11 is configured by the reset transistor 33, the output transistor 32, and the selection transistor 34 are n-channel MOS transistors, and holes are collected by the pixel electrode 12. However, the present invention is not limited thereto, and the reset transistor 33, the output transistor 32, and the selection transistor 34 are configured by p-channel MOS transistors, and electrons are collected by the pixel electrode 12, and a charge signal corresponding to the amount of the electrons is obtained. Reading may be performed by the signal reading circuit 11 configured by a p-channel MOS transistor.
上記実施形態のように画素電極12で正孔を捕集し、これをnチャネルMOSトランジスタで構成された信号読出回路11で読み出す構成としたり、もしくは上述したように画素電極12で電子を捕集し、これをpチャネルMOSトランジスタで構成された信号読出回路11読み出す構成とした場合、画素電極によって電子を捕集し、これをnチャネルMOSトランジスタで構成された信号読出回路によって読み出す構成とした場合と比較すると、飽和電子数を大きくすることができ、飽和しやすいW画素のダイナミックレンジを大きくすることができる。なお、従前のシリコン基板中に形成されるフォトダイオードでは、信号読出回路とフォトダイオードを同じ基板中に形成するため、読出回路の極性と捕集電荷の極性を逆極性とすることができなかった。
As in the above embodiment, holes are collected by the pixel electrode 12 and read out by the signal readout circuit 11 constituted by an n-channel MOS transistor, or electrons are collected by the pixel electrode 12 as described above. When this is configured to read out the signal readout circuit 11 configured by a p-channel MOS transistor, the electron is collected by the pixel electrode and read out by a signal readout circuit configured from an n-channel MOS transistor. As compared with, the number of saturated electrons can be increased, and the dynamic range of the W pixel which is easily saturated can be increased. In the photodiode formed in the conventional silicon substrate, since the signal readout circuit and the photodiode are formed in the same substrate, the polarity of the readout circuit and the polarity of the collected charge could not be reversed. .
図21は、本実施形態の固体撮像素子100の全体構成を示す図である。図21に示すように、本実施形態の固体撮像素子100は、垂直ドライバ121と、制御部122と、信号処理回路123と、水平ドライバ124と、LVDS125と、シリアル変換部126と、パッド127とを含む周辺回路と、図11に示す画素部20が複数2次元状に配列された画素領域(撮像部に相当する)とを備えている。図21の画素領域については、画素部20の信号読出回路11のみを模式的に示している。
FIG. 21 is a diagram showing an overall configuration of the solid-state imaging device 100 of the present embodiment. As shown in FIG. 21, the solid-state imaging device 100 of the present embodiment includes a vertical driver 121, a control unit 122, a signal processing circuit 123, a horizontal driver 124, an LVDS 125, a serial conversion unit 126, a pad 127, and the like. And a pixel region (corresponding to an imaging unit) in which a plurality of pixel units 20 shown in FIG. 11 are arranged two-dimensionally. In the pixel region of FIG. 21, only the signal readout circuit 11 of the pixel unit 20 is schematically shown.
制御部122は、タイミングジェネレータなどを備えたものであり、フレーム同期信号VDや行同期信号HDを出力するとともに、垂直ドライバ121や水平ドライバ124の動作を制御することによって画素部20における電荷信号の読出しなどを制御するものである。
The control unit 122 includes a timing generator and the like, outputs the frame synchronization signal VD and the row synchronization signal HD, and controls the operations of the vertical driver 121 and the horizontal driver 124 to control the charge signal in the pixel unit 20. It controls reading and the like.
垂直ドライバ121は、制御部122から出力されたフレーム同期信号VDおよび行同期信号HDに基づいて、信号読出回路11に対してリセットパルスRSや選択パルスRWを出力し、信号読出回路11におけるリセット動作や電荷信号の読出し動作を制御するものである。
The vertical driver 121 outputs a reset pulse RS and a selection pulse RW to the signal readout circuit 11 based on the frame synchronization signal VD and the row synchronization signal HD output from the control unit 122, and a reset operation in the signal readout circuit 11. And the charge signal reading operation.
信号処理回路123は、信号読出回路11の各列に対応して設けられるものである。信号処理回路123は、対応する列から出力された信号に対し、相関二重サンプリング(CDS)処理を行ない、処理後の信号をデジタル信号に変換するADC回路を備えたものである。信号処理回路123で処理後の信号は、列毎に設けられたメモリに記憶される。
The signal processing circuit 123 is provided corresponding to each column of the signal readout circuit 11. The signal processing circuit 123 includes an ADC circuit that performs correlated double sampling (CDS) processing on the signals output from the corresponding columns and converts the processed signals into digital signals. The signal processed by the signal processing circuit 123 is stored in a memory provided for each column.
水平ドライバ124は、信号処理回路123のメモリに記憶された画素部20の1行分の信号を順次読出してLVDS125に出力する制御を行うものである。
The horizontal driver 124 controls to sequentially read out signals for one row of the pixel unit 20 stored in the memory of the signal processing circuit 123 and output the signals to the LVDS 125.
LVDS125は、LVDS(low voltage differential signaling)に従ってデジタル信号を伝送する。シリアル変換部126は、入力されるパラレルのデジタル信号をシリアルに変換して出力するものである。パッド127は、外部との入出力に用いるインターフェースである。
The LVDS 125 transmits a digital signal in accordance with LVDS (low voltage differential). The serial conversion unit 126 converts an input parallel digital signal into a serial signal and outputs it. The pad 127 is an interface used for input / output with the outside.
なお、本実施形態においてはカラーフィルタ上にマイクロレンズを備えていない構成を説明したが、カラーフィルタ上にマイクロレンズを備えていてもよい。
In the present embodiment, the configuration in which the microlens is not provided on the color filter has been described, but the microlens may be provided on the color filter.
上述した実施形態の固体撮像素子は、種々の撮像装置に用いることができる。撮像装置としては、たとえばデジタルカメラ、デジタルビデオカメラ、電子内視鏡、カメラ付携帯電話などがある。
The solid-state imaging device of the above-described embodiment can be used for various imaging devices. Examples of the imaging device include a digital camera, a digital video camera, an electronic endoscope, and a camera-equipped mobile phone.
Claims (9)
- 基板上に画素単位で区画された画素電極、入射光の光量に応じた信号電荷を発生する光電変換膜、および該光電変換膜を挟んで前記画素電極に対向して設けられた対向電極を含む光電変換部を有する画素が、二次元状に複数配列されてなる撮像部を有する固体撮像素子において、
前記光電変換膜および前記対向電極が、全ての前記画素に共通な共通膜状に形成されてなり、
前記対向電極上に保護膜を備え、
前記保護膜上に、異なる複数色のカラーフィルタを有するカラーフィルタ層が、該各カラーフィルタが前記各光電変換部と対応するように配置され、
該カラーフィルタ層が、前記異なる複数色のカラーフィルタとして、所定の色領域の波長のみを透過する所定色フィルタと、該所定色フィルタに隣接して配置された全可視光領域に亘る波長を透過する白色フィルタとを含み、少なくとも前記所定の色領域の波長以外の可視光領域において、前記所定色フィルタと前記白色フィルタとの間に屈折率差を有するものであり、
前記カラーフィルタ層の底面から前記光電変換膜の上面までの光路長d1が1.2μm以下であり、
前記光電変換膜の厚みの光路長d2が1.4μm以下であることを特徴とする固体撮像素子。 A pixel electrode partitioned on a substrate on a substrate; a photoelectric conversion film that generates a signal charge according to the amount of incident light; and a counter electrode provided to face the pixel electrode across the photoelectric conversion film In a solid-state imaging device having an imaging unit in which a plurality of pixels having a photoelectric conversion unit are two-dimensionally arranged,
The photoelectric conversion film and the counter electrode are formed in a common film shape common to all the pixels,
A protective film is provided on the counter electrode,
On the protective film, color filter layers having different color filters are arranged so that each color filter corresponds to each photoelectric conversion unit,
The color filter layer, as the different color filters, transmits a predetermined color filter that transmits only a wavelength in a predetermined color region, and a wavelength that extends over the entire visible light region disposed adjacent to the predetermined color filter. A white filter that has a refractive index difference between the predetermined color filter and the white filter at least in a visible light region other than the wavelength of the predetermined color region,
An optical path length d 1 from the bottom surface of the color filter layer to the top surface of the photoelectric conversion film is 1.2 μm or less;
A solid-state imaging device optical path length d 2 of the thickness of the photoelectric conversion film is equal to or less than 1.4 [mu] m. - 前記光電変換膜が有機材料を含むものであることを特徴とする請求項1記載の固体撮像素子。 The solid-state imaging device according to claim 1, wherein the photoelectric conversion film contains an organic material.
- 前記白色フィルタと前記所定色フィルタとの屈折率差をΔnとすると、前記所定色フィルタが透過しない可視光波長領域においてΔnと前記光路長d1(μm)、d2(μm)との間に、
Δn × (d1+d2)2< 2.0
の関係が成り立つことを特徴とする請求項1または2記載の固体撮像素子。 Assuming that the refractive index difference between the white filter and the predetermined color filter is Δn, between Δn and the optical path lengths d 1 (μm) and d 2 (μm) in a visible light wavelength region that the predetermined color filter does not transmit. ,
Δn × (d 1 + d 2 ) 2 <2.0
The solid-state imaging device according to claim 1, wherein the relationship is established. - 前記所定の色が青、緑および赤のいずれかであることを特徴とする請求項1から3いずれか1項記載の固体撮像素子。 The solid-state imaging device according to any one of claims 1 to 3, wherein the predetermined color is any one of blue, green, and red.
- 前記所定の色領域の波長のみを透過する前記所定色フィルタとして、青色領域の波長のみを透過する青色フィルタ、緑色領域の波長のみを透過する緑色フィルタ、および赤色領域の波長のみを透過する赤色フィルタを備えたことを特徴とする請求項1から3いずれか1項記載の固体撮像素子。 As the predetermined color filter that transmits only the wavelength of the predetermined color region, a blue filter that transmits only the wavelength of the blue region, a green filter that transmits only the wavelength of the green region, and a red filter that transmits only the wavelength of the red region The solid-state imaging device according to claim 1, further comprising:
- 前記所定の色領域の波長のみを透過する前記所定色カラーフィルタとして、黄色領域の波長のみを透過する黄色フィルタ、マゼンダ領域の波長のみを透過するマゼンダフィルタ、シアン領域の波長のみを透過するシアンフィルタを備えたことを特徴とする請求項1から3いずれか1項記載の固体撮像素子。 As the predetermined color filter that transmits only the wavelength of the predetermined color region, a yellow filter that transmits only the wavelength of the yellow region, a magenta filter that transmits only the wavelength of the magenta region, and a cyan filter that transmits only the wavelength of the cyan region The solid-state imaging device according to claim 1, further comprising:
- 前記基板に前記光電変換部において生じる電荷に応じた信号を読み出すMOSトランジスタ回路が形成されており、該MOSトランジスタ回路は、前記光電変換部と電気的に接続された電荷蓄積部と、前記電荷蓄積部の電位をリセット電位にリセットするリセットトランジスタと、前記電荷蓄積部の電位に応じた信号を出力する出力トランジスタとを含み、前記リセットトランジスタ及び前記出力トランジスタは、キャリアの極性が前記光電変換部で発生した捕集される電荷と逆極性であることを特徴とする請求項1から6いずれか1項記載の固体撮像素子。 A MOS transistor circuit is formed on the substrate to read out a signal corresponding to the charge generated in the photoelectric conversion unit. The MOS transistor circuit includes a charge storage unit electrically connected to the photoelectric conversion unit, and the charge storage unit. A reset transistor that resets the potential of the unit to a reset potential, and an output transistor that outputs a signal corresponding to the potential of the charge storage unit. The reset transistor and the output transistor have a carrier polarity in the photoelectric conversion unit. The solid-state imaging device according to any one of claims 1 to 6, wherein the solid-state imaging device has a polarity opposite to that of the generated charges to be collected.
- 前記光電変換膜と前記画素電極との間に、暗電流を抑制する機能層が設けられていることを特徴とする請求項1から7いずれか1項記載の固体撮像素子。 A solid-state imaging device according to any one of claims 1 to 7, wherein a functional layer for suppressing dark current is provided between the photoelectric conversion film and the pixel electrode.
- 請求項1から8いずれか1項記載の固体撮像素子を備えたことを特徴とする撮像装置。 An image pickup apparatus comprising the solid-state image pickup device according to any one of claims 1 to 8.
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CN110959194B (en) * | 2017-08-03 | 2024-02-20 | 索尼半导体解决方案公司 | Solid-state imaging device and electronic apparatus |
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KR101676972B1 (en) | 2016-11-29 |
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