JP2019102623A - Color imaging device and manufacturing method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vertical color separation type color image sensor which is excellent in color selectivity and photoelectric conversion efficiency, has good signal readout characteristics, and can be manufactured without a complicated process. A color image pickup device (10) forms a second image pickup device (12) on a third image pickup device (13), which is a CMOS image sensor including an embedded photodiode 23 formed on a Si substrate (20). It is manufactured by turning over the first image sensor 11 formed on the transparent substrate 91 and joining them. The first image sensor 11 and the second image sensor 12 respectively form the organic photoelectric conversion films 41 and 42 after forming the read circuits 61 and 62 by the TFT using a high temperature process. [Selection diagram] Fig. 2

Description

  The present invention relates to a vertical color separation type color imaging device and a method of manufacturing the same.

  There are single-plate and multi-plate color imaging devices (image sensors) used in television (TV) cameras and digital cameras. The single-plate type has minute color filters of each color of red (R), green (G), and blue (B) arranged in a mosaic on one solid-state imaging device, and the light transmitted for each color filter is Convert to electrical signals. For a solid-state imaging device (hereinafter, imaging device), a photodiode made of silicon (Si) having a wide spectral sensitivity including a visible region is applied to a photoelectric conversion device, for example. It can form (for example, patent documents 1 and 2). The single-plate type is relatively compact and is mainly adopted for consumer video cameras, digital cameras, and the like because only one image sensor is required (Non-Patent Document 1). However, in the single plate type, since one pixel is formed of one color, the resolution is low with respect to the pixel size, and light of other colors is absorbed by the color filter, so the utilization efficiency of incident light is low. On the other hand, in the multi-plate type (three-plate type), light incident on the camera through the lens is separated into single colors of red, green, and blue by a color separation prism, and light of each color is made incident on separate imaging devices . The multi-plate type is adopted for TV cameras and the like that require high resolution and high sensitivity, but since three imaging elements are disposed on the light extraction surface of each color of the color separation prism, downsizing of the camera etc. It is difficult to reduce the weight.

  Therefore, in order to simultaneously achieve high resolution, high sensitivity, and miniaturization, a vertical color separation type color imaging device in which photoelectric conversion devices are arranged in three layers in the light entering direction has been developed. For example, as a photoelectric conversion element, a color imaging element in which Si photodiodes are stacked in three layers on a Si substrate is disclosed (for example, Patent Document 3). This utilizes the fact that the penetration depth of light in silicon is as deep as the wavelength, and the Si photodiodes in each layer absorb blue light, green light, and red light in order from the light incident side to charge them. Convert to

  In addition, a color imaging device is disclosed in which imaging devices including photoelectric conversion materials that absorb light in a specific wavelength range and convert it into charges and transmit light other than that are stacked. As such a photoelectric conversion material, many materials made of an organic material excellent in color selectivity and photoelectric conversion efficiency are applied. Specifically, an image pickup element in which a photoelectric conversion film made of a photoelectric conversion material is sandwiched between counter electrodes and pixel electrodes partitioned for each pixel from above and below, and an electric signal readout circuit is connected to the pixel electrodes is a photoelectric conversion material. It is laminated in three different layers. Readout circuits for electrical signals, wirings, and electrodes are formed of thin film transistors (TFTs) or transparent electrode materials so as to transmit light (for example, Patent Documents 4 to 7). Alternatively, a color imaging device in which a readout circuit is formed of a transistor formed on a Si substrate, and three sets of photoelectric conversion films sandwiched between pixel electrodes and counter electrodes are stacked, or a lower side (opposite side of light incident side Patent Document 8 and 9 disclose color imaging devices in which the first and second layers are replaced with a Si photodiode similarly formed on a Si substrate.

Patent No. 3759435 JP, 2015-56518, A Japanese Patent Application Publication No. 2002-513145 JP 2005-51115 A Patent No. 5102692 Japanese Patent Application Laid-Open No. 2002-217174 Patent No. 5572108 gazette JP 2007-311647 A JP, 2017-174936, A

Y. Kiuchi, "Basics and Applications of Image Sensors", Nikkan Kogyo Shimbun, December 25, 1991, p. 145

  However, in the imaging device in which the Si photodiodes described in Patent Document 3 are stacked, for example, the Si photodiode for blue light photoelectric conversion absorbs the green light and the red light to some extent, so the color separation characteristics are insufficient. In addition, since the transistors of the readout circuit for three layers are formed on the same layer of the Si substrate together with the Si photodiode, the area ratio (aperture ratio) of the light receiving portion (Si photodiode) is low and the light utilization efficiency is sufficient. Absent.

  The imaging device described in Patent Documents 4 and 5 is obtained by forming a thin film transistor and a photoelectric conversion film on each of three glass substrates and bonding them together. Therefore, since the distance between the photoelectric conversion films of each layer becomes wide with the thickness of the glass substrate, it is difficult to focus incident light on all the photoelectric conversion films and reach them, and there is room for improvement. On the other hand, in the imaging devices described in Patent Documents 6 and 7, thin film transistors and photoelectric conversion films are alternately formed on one glass substrate, so that the shift of the focal point of incident light is small. However, since the photoelectric conversion film made of an organic material is weak to heat at a heat resistance temperature of about 150 ° C., the thin film transistor formed thereon is limited to a semiconductor material which can be formed at a low temperature such as room temperature. Such a thin film transistor is inferior in characteristics such as low electron mobility as compared with a thin film transistor formed of a semiconductor material deposited at about 300 to 400 ° C. On the other hand, a photoelectric conversion film made of a heat-resistant inorganic material also absorbs light of a shorter wavelength than the wavelength region targeted for photoelectric conversion, and thus converts light of a shorter wavelength region on the light incident side Thus, constraints are imposed in the order of B, G, R.

  In the imaging device in which two or three layers of photoelectric conversion films described in Patent Documents 8 and 9 are stacked on a Si substrate, the pixel electrode of the photoelectric conversion film of the uppermost layer (light incident side) is connected to the transistor of the readout circuit. In order to achieve this, it is necessary to form vias (through electrodes) that reach from the pixel electrode to the Si substrate. However, it is difficult to process a photoelectric conversion film made of an organic material below the uppermost layer to form a through hole (via hole) passing through the via.

  The present invention has been made in view of the above problems, and has excellent color selectivity and photoelectric conversion efficiency, good signal readout characteristics, and vertical color separation which can be manufactured without complicated processes. It is an object of the present invention to provide a type color imaging device.

  A color imaging device according to the present invention comprises: a first photoelectric conversion layer which absorbs light in a first wavelength range to convert it into electric charge, and transmits light in a second wavelength range and a third wavelength range; A second photoelectric conversion layer that absorbs light in the second wavelength range and converts it into charge and transmits light in the third wavelength range; and at least in part of the third wavelength range A third photoelectric conversion layer which absorbs light and converts it into charges is provided in order from the top, and light including a plurality of wavelength ranges is incident from the top. The color imaging device further includes a first readout circuit provided with a thin film transistor and outputting the electric charge converted by the first photoelectric conversion layer as an electric signal, above the first photoelectric conversion layer. A second readout circuit for outputting the charge converted by the second photoelectric conversion layer as an electric signal, and a third readout circuit for outputting the electric charge converted by the third photoelectric conversion layer as an electric signal; It is provided below the second photoelectric conversion layer, and each of the first photoelectric conversion layer and the second photoelectric conversion layer contains an organic material, and both surfaces are sandwiched by transparent electrode films. I assume.

  With this configuration, the color imaging device can be provided by repeatedly laminating the readout circuit formed at high temperature and the photoelectric conversion layer made of an organic material at short intervals.

  In the method of manufacturing a color imaging device according to the present invention, an imaging unit laminate forming step of forming an imaging unit for converting light of two or more wavelength regions into an electric signal for each wavelength region and outputting the electric signal on a lower substrate; An upper imaging means forming step of forming on the transparent substrate an imaging means for converting light of a wavelength range different from the two or more wavelength ranges into an electric signal and outputting the electric signal; A substrate bonding step of bonding with a transparent substrate is performed. The upper imaging means forming step includes a first thin film transistor forming step of forming a thin film transistor on the transparent substrate, a first pixel electrode forming step of forming a transparent electrode film in a predetermined region, and a photoelectric conversion layer. A first photoelectric conversion layer forming step and a first counter electrode film forming step of laminating a transparent electrode film on the photoelectric conversion layer are performed, and in the imaging unit laminate forming step, a transistor and photoelectric conversion are provided on the lower substrate. Layer forming step, a second pixel electrode forming step of forming a transparent electrode film in a predetermined area, and a second photoelectric conversion layer forming a photoelectric conversion layer on the side on which the transparent electrode film is formed A forming step and a second counter electrode film forming step of laminating a transparent electrode film on the photoelectric conversion layer are performed, and in the substrate bonding step, the transparent electrode film of the lower substrate and the transparent substrate is formed ~ side At least one of before the first photoelectric conversion layer forming process in the upper imaging means forming process and before the second photoelectric conversion layer forming process in the imaging means laminate forming process, Heat treatment is performed.

  According to this procedure, the readout circuit can be formed at high temperature and the photoelectric conversion layer can be formed of an organic material regardless of complicated steps.

  According to the color imaging device of the present invention, it is possible to obtain a vertical color separation type color imaging device which is excellent in color selectivity and photoelectric conversion efficiency and has a good signal readout characteristic. According to the method of manufacturing a color imaging device according to the present invention, the color imaging device can be easily manufactured.

It is a schematic diagram explaining the concept of the color imaging device which concerns on this invention. It is a fragmentary sectional view which illustrates the structure of the color imaging device concerning a 1st embodiment of the present invention typically. It is an equivalent circuit schematic of 1 pixel of the image pick-up element which comprises a color image pick-up element. It is an equivalent circuit schematic of 1 pixel of the image pick-up element which comprises a color image pick-up element. It is an equivalent circuit schematic of 1 pixel of the image pick-up element which comprises a color image pick-up element. It is a fragmentary sectional view which explains typically the structure of the 1st image sensor which constitutes the color image sensor concerning the present invention. It is a flow chart explaining a manufacturing method of a color image sensor concerning the present invention. It is a flowchart explaining the upper imaging means formation process in the manufacturing method of the color imaging device concerning this invention. It is a flowchart explaining the imaging means laminated body formation process in the manufacturing method of the color imaging device which concerns on 1st Embodiment of this invention. It is a fragmentary sectional view which illustrates the structure of the color imaging device concerning the modification of a 1st embodiment of the present invention typically. It is a flowchart explaining the imaging means laminated body formation process in the manufacturing method of the color imaging device concerning the modification of 1st Embodiment of this invention. It is a fragmentary sectional view which illustrates the structure of the color imaging device concerning a 2nd embodiment of the present invention typically. It is a flowchart explaining the imaging means laminated body formation process in the manufacturing method of the color imaging device concerning 2nd Embodiment of this invention. It is a fragmentary sectional view which illustrates the structure of the color imaging device concerning a 3rd embodiment of the present invention typically. It is a flowchart explaining the imaging means laminated body formation process in the manufacturing method of the color imaging device which concerns on 3rd Embodiment of this invention.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS A color imaging device according to the present invention and a mode for carrying out the manufacturing method thereof will be described with reference to the drawings. The color imaging device and its elements shown in the drawings may exaggerate the size, positional relationship, etc. in order to clarify the description, and may simplify the shape.

[Color imaging device]
The color imaging device arranges a desired number of pixels in a two-dimensional array in a plane, and lights L1, L2, and L3 of three wavelength ranges included in light incident from above (refers to light including visible light). , Individually convert them into electric signals IS1, IS2, and IS3 and output them. Therefore, as shown in FIG. 1, the color imaging device 10 absorbs the light L1 in the first wavelength range and converts it into electric charge in order from the top, and converts the light L2 in the second and third wavelength ranges into light A first photoelectric conversion layer 41 transmitting L3, and a second photoelectric conversion layer 42 absorbing the light L2 in the second wavelength range and converting it into a charge, and transmitting the light L3 in the third wavelength range , And a third photoelectric conversion layer 23 for absorbing light L3 in the third wavelength range and converting it into charges, and further, the charges converted from the lights L1, L2, and L3 are converted to electric signals IS1, IS2, and The readout circuits 61, 62, 63 output as IS3 are provided. Hereinafter, an embodiment of a color imaging device according to the present invention will be described in detail.

First Embodiment
As shown in FIG. 2, the color imaging device 10 according to the first embodiment of the present invention includes a first organic photoelectric conversion film (first photoelectric conversion layer) 41 and a second organic photoelectric conversion film (second photoelectric A conversion layer) 42 and a photodiode (third photoelectric conversion layer) 23 are provided in order from the top, and further, a first circuit layer (first readout circuit) 61 is formed on the first organic photoelectric conversion film 41. A third circuit portion (third readout circuit) 63 on the Si substrate 20 on which the second circuit layer (second readout circuit) 62 is formed under the second organic photoelectric conversion film 42 and on which the photodiode 23 is formed. Are provided on the Si substrate 20 and the wiring 31 formed thereunder. The color imaging device 10 further includes a transparent substrate 91 for transmitting incident light on the first circuit layer 61, an insulating film 83 for insulating the wiring 31 under the Si substrate 20, and an interlayer film on the Si substrate 20. Each has 84. The first organic photoelectric conversion film 41 is sandwiched between the pixel electrode 51 and the counter electrode 52 on the upper and lower surfaces, and the second organic photoelectric conversion film 42 is sandwiched between the counter electrode 54 and the pixel electrode 53 on the upper and lower surfaces. In FIG. 2, the boundaries between the pixels of the color imaging device 10 are indicated by alternate long and short dashed lines. In the present embodiment, light L1, L2 and L3 in the first, second and third wavelength ranges are respectively green light L _G (peak wavelength 500 to 540 nm), blue light L _B (peak wavelength 450 nm) and red light Description will be made by setting it to L _R (peak wavelength 650 nm).

  The color imaging device 10 can include a microlens for each pixel on the transparent substrate 91 (not shown). Preferably, the color imaging device 10 further includes a filter (not shown) that absorbs light outside the visible region, such as infrared light, between the transparent substrate 91 and the microlens.

  It is preferable that the color imaging element 10 has a short distance (length in the thickness direction) from the upper surface (the surface on the light incident side, light receiving surface) of the first organic photoelectric conversion film 41 to the light receiving surface of the photodiode 23. As the distance is shorter, in any of the first organic photoelectric conversion film 41, the second organic photoelectric conversion film 42, and the photodiode 23, the shift of the focal point of the incident light is suppressed. Specifically, the distance (hereinafter, light receiving surface difference) from the upper surface of the first organic photoelectric conversion film 41 to the upper surface of the photodiode 23 (position from the upper surface of the Si substrate 20 to a predetermined depth) is 10 μm or less Preferably, the distance from the upper surface of the first organic photoelectric conversion film 41 to the lower surface of the photodiode 23 is 10 μm or less.

  Further, in the color imaging device 10, a portion including the first organic photoelectric conversion film 41 and the first circuit layer 61 is referred to as a portion including the first imaging device 11, the second organic photoelectric conversion film 42 and the second circuit layer 62 The portion provided with the imaging device 12, the photodiode 23, and the third circuit unit 63 is referred to as a third imaging device 13, respectively. That is, the imaging elements 11, 12 and 13 are imaging elements of light of one wavelength range (monochromatic light). One pixel of the first imaging device 11 and the second imaging device 12 is represented, for example, by an equivalent circuit diagram shown in FIG. 3 or FIG. 4. One pixel of the third imaging element 13 is represented, for example, by an equivalent circuit diagram shown in FIG.

  FIG. 3 shows a pixel of the simplest configuration provided with a photodiode PD and a selection transistor T1. The photodiode PD is disposed between the first organic photoelectric conversion film 41 for one pixel sandwiched between the pair of electrodes 51 and 52 of the first imaging device 11 and the pair of electrodes 53 and 54 of the second imaging device 12. It is a second organic photoelectric conversion film 42 for a pixel. The electrodes 51 and 52 and the electrodes 53 and 54 are terminals of the photodiode PD. The side of the photodiode PD connected to the pixel electrodes 51 and 53 is connected to the source or drain of the selection transistor T1. The photodiode PD is connected to a reverse bias to function as a capacitor, and accumulates charge upon light reception. In FIG. 3, the anode is connected to the selection transistor T1 and the cathode is connected to a common external power supply PS. When the select transistor T1 is selected by the pixel select line SL, the accumulated charge is output as an electrical signal to the read line OL via the select transistor T1.

FIG. 4 shows a pixel of a 1-pixel 3T-type image sensor including three transistors T1, T2 and T3. An amplification transistor T2 is connected to the selection transistor T1, and a photodiode PD is connected to the gate of the amplification transistor T2. ing. With such a configuration, the electric signal of the photodiode PD is output as a voltage from the drain power supply V _DD via the amplification transistor T2 and the selection transistor T1. The reset transistor T3 initializes the charge stored in the photodiode PD when it is selected by the reset selection line RL. The reset power supply V _RST may be common to the drain power supply V _DD .

  FIG. 5 shows an example of a pixel of a Complementary Metal-Oxide Semiconductor (CMOS) image sensor having a buried photodiode and a 1-pixel 4T-type having four transistors T1, T2, T3 and T4. In the figure, the photodiode PD is the photodiode 23 in the third imaging device 13. The third imaging device 13 has a transfer transistor T4 inserted between the photodiode PD of the first imaging device 11 of 1 pixel 3T type shown in FIG. 4 and the gate of the amplification transistor T2, and the anode and the cathode of the photodiode PD. And the anode is connected to GND. The transfer transistor T4 completely transfers the charge stored in the floating diffusion layer (FD) of the photodiode PD when selected by the transfer selection line TL, thereby eliminating the occurrence of an afterimage and noise due to the residual charge. The first imaging device 11 and the second imaging device 12 may also be one-pixel 4T-type pixels. In this case, the transfer transistor T4 is inserted between the photodiode PD of FIG. 4 and the gate of the amplification transistor T2. Do.

  The first imaging device 11 is formed by laminating a protective film 81, an opposing electrode 52, a first organic photoelectric conversion film 41, a pixel electrode 51, and a first circuit layer 61 in order from the bottom, and further on the transparent substrate 91 It is provided. The second imaging element 12 is formed by laminating the second circuit layer 62, the pixel electrode 53, the second organic photoelectric conversion film 42, the counter electrode 54, and the protective film 82 in order from the bottom. The first imaging device 11 and the second imaging device 12 have substantially the same layered structure except that the stacking order is reversed. This is because the first imaging device 11 is sequentially formed from the light incident side with the transparent substrate 91 as a base, as described later in the manufacturing method, and the transparent substrate 91 is directed downward in FIG. Shows a cross-sectional view. On the other hand, the third imaging device 13 is a backside illuminated CMOS image sensor (for example, Patent Documents 1 and 2), and an Si substrate 20 on which an insulating film 83, a wiring 31, and a photodiode 23 are formed in order from the bottom, an interlayer film. 84 is stacked. Hereinafter, each element of the color imaging device 10 will be described in detail.

(Transparent substrate)
The transparent substrate 91 is a base for forming the first imaging device 11 as described above, and the first imaging device 11 is formed on the surface (lower surface) opposite to the light incident side. The transparent substrate 91 is provided on the uppermost layer in the color imaging element 10, and thus is formed of an insulating material that transmits light (visible light) and has a heat resistant temperature for forming the first circuit layer 61. Specifically, SiO ₂ (silicon oxide, glass), MgO (magnesium oxide), sapphire, GGG (gadolinium gallium garnet) and the like can be mentioned.

(First organic photoelectric conversion film, second organic photoelectric conversion film)
Each of the first organic photoelectric conversion film 41 and the second organic photoelectric conversion film 42 has sensitivity to light of a specific wavelength range, absorbs it, converts it into electric charge, and transmits the remaining light from organic materials Become. By applying such a material to the photoelectric conversion layer other than the lowermost layer (photodiode 23), it is possible to receive light of each color of R, G, and B in an arbitrary order from the light incident side. In the present embodiment, most first organic photoelectric conversion layer 41 arranged on the incident side closer to apply an organic material having a high sensitivity to green light L _G luminosity, blue second organic photoelectric conversion layer 42 applying an organic material having sensitivity to light L _B. The film thickness of the organic photoelectric conversion films 41 and 42 is preferably 50 nm or more, and the absorptivity at the light absorption maximum wavelength is 90% or more, that is, the absorbance A (A = −log (I / I ₀ ), (I It is preferable that / I ₀ : transmittance)) is 1.0 or more. On the other hand, since the distance from the first organic photoelectric conversion film 41 to the photodiode 23 in the color imaging device 10 becomes long, the thickness of each of the organic photoelectric conversion films 41 and 42 is preferably 1 μm or less.

  Coumarin derivatives and porphyrin derivatives as organic materials sensitive to only blue light, quinacridone derivatives and perylene derivatives as organic materials sensitive to only green light, phthalocyanine derivatives and organic materials sensitive to only red light Naphthalocyanine derivatives are mentioned. Besides, acridine, cyanine, squarylium, oxazine, xanthene triphenylamine, benzidine, pyrazoline, stilylamine, hydrazone, triphenylmethane, carbazole, polysilane, thiophene, polyamine, oxadiazole, triazole, triazine, quinoxaline, phenanth Lorin, fullerene, aluminum quinoline, polyparaphenylene vinylene, polyfluorene, polyvinylcarbazole, polythiol, polypyrrole, polythiophene and derivatives thereof alone or a mixture or lamination of two or more kinds of organic materials represented by these It is possible to prepare organic materials that are sensitive only to blue light, green light or red light.

  The first organic photoelectric conversion film 41 and the second organic photoelectric conversion film 42 are for reducing dark current (current output when light is not incident) and improving the quantum efficiency of the organic photoelectric conversion films 41 and 42. , An electron transport material, a hole transport material, an electron injection blocking (electron blocking) material, a hole injection blocking (hole blocking) material, etc. even when mixed or laminated to the organic material (organic photoelectric conversion material) Good. Examples of electron injection blocking materials include triphenylamine compounds, styrylamine compounds, carbazole compounds and the like, and hole injection blocking materials include phenanthroline compounds, aluminum quinoline compounds and oxadiazole compounds And silole compounds and the like, and materials generally used in organic devices can be applied. As the electron injection blocking material and the hole injection blocking material, inorganic materials can also be used. When these materials are provided, an electron injection blocking layer or a hole injection blocking layer may be laminated on one side of the organic photoelectric conversion layer, or an electron injection blocking layer and a hole injection blocking layer may be laminated on each side. Is preferred.

(Pixel electrode, counter electrode)
The pixel electrode 51 and the counter electrode 52 are connected to both sides of the first organic photoelectric conversion film 41, and the pixel electrode 53 and the counter electrode 54 are connected to both sides of the second organic photoelectric conversion film 42, which are a pair of electrodes. The pixel electrodes 51 and 53 are formed in a pattern divided and separated for each pixel of the color imaging element 10, and electrically connected to the transistors of the circuit layers 61 and 62 (see FIGS. 3 and 4). The counter electrodes 52 and 54 are formed on the entire surface and connected to an external power supply or GND. The pixel electrodes 51 and 53 and the counter electrodes 52 and 54 are formed to have a film thickness that can achieve the required conductivity, and specifically, the film thickness is preferably 1 to 100 nm.

The pixel electrodes 51 and 53 are formed of a transparent electrode material in order to allow the light to reach the organic photoelectric conversion films 41 and 42 and the photodiode 23. As transparent electrode materials, indium tin oxide (ITO), fluorine-doped tin oxide (FTO), antimony-doped tin oxide (ATO), indium oxide / zinc oxide (IZO), zinc oxide (ZnO), tin oxide (SnO ₂₎ And the like, and two or more of these films may be laminated. Similar to the pixel electrodes 51 and 53, the counter electrodes 52 and 54 can be formed of the above-described transparent electrode material so as to transmit light. However, since the counter electrodes 52 and 54 are formed on the organic photoelectric conversion films 41 and 42, ITO, IZO or the like is preferable because relatively good conductivity can be obtained even without film formation (such as room temperature). is there. In addition, conductive polymers represented by polyacetylene type, polyaniline type, polypyrrole type, and polythiophene type can also be used as the counter electrodes 52 and 54. In addition, the counter electrodes 52 and 54 may be semitransparent electrodes made of metal electrode materials listed as the gate electrodes 71 and the like of the first circuit layer 61 and the second circuit layer 62 described later.

  A buffer layer may be provided between the first organic photoelectric conversion film 41 and the counter electrode 52, and between the second organic photoelectric conversion film 42 and the counter electrode 54 (not shown). By providing the buffer layer, damage to the organic photoelectric conversion films 41 and 42 can be reduced when the counter electrodes 52 and 54 are formed. The buffer layer preferably has a thickness of 10 to 500 nm. As the buffer layer, dipyrazino [2,3-f: 2 ′, 3′-h] quinoxaline-2,3,6,7,10,11-hexacarbonitrile (HAT-CN), naphthalene-1,4 , 5, 8- tetracarboxylic acid dianhydride (NTCDA) etc. can be applied.

(First circuit layer, second circuit layer)
The first circuit layer 61 and the second circuit layer 62 have a thin film transistor (TFT) structure, and have the same laminated structure except that the order of lamination is reversed. Furthermore, as shown in FIG. 2, the first circuit layer 61 and the second circuit layer 62 are designed such that the layouts at the time of their formation are mirror images of each other so that the first circuit layer 61 and the second circuit layer 62 overlap in plan view. It may be a different circuit. As shown in FIG. 6, the first circuit layer 61 is, for example, a semiconductor layer 6, a gate insulating film 86, an insulating film 87, a gate electrode 71, a source / drain electrode 72, and a horizontal signal line (figure 3 and FIG. 4 and the vertical signal line (read line OL, V _DD power supply wiring, V _RST power supply wiring shown in FIGS. 3 and 4), and a protective film 88 Prepare. The first circuit layer 61 is formed by depositing a material for each of these elements and patterning it by etching, as will be described later in the manufacturing method. The same applies to the second circuit layer 62. It is preferable that the circuit layers 61 and 62 have a structure in which at least a part of the region transmits light for each pixel, and transmits light at a higher area ratio. The second circuit layer 62 preferably has a thickness of at most 1 μm or less. Therefore, it is preferable that the protective film 88 or the like is not formed to be excessively thick as a film thickness that can ensure necessary insulation and the like.

The semiconductor layer 6 can apply the semiconductor material applied to TFT, and the material which has high electron mobility is preferable. The electron mobility of the semiconductor layer 6 is preferably 5 cm ² / V · s or more, and more preferably 10 cm ² / V · s or more. The semiconductor layer 6 is formed to exhibit such high electron mobility at a film forming temperature or an annealing temperature of about 300 to 450 ° C., depending on the material and the like. The semiconductor layer 6 is preferably made of a material having a band gap of 3.0 eV or more in order to absorb visible light (light L _R , L _G , L _B ) and prevent the switching response of the semiconductor from changing. And highly transparent materials are preferred. As such a semiconductor material, zinc oxide (ZnO), an amorphous oxide semiconductor (indium gallium, zinc oxide: InGaZnO ₄ ) and the like can be mentioned. The semiconductor layer 6 provided in the second circuit layer 62 further applies a material formed at a heat resistance temperature or less of the third imaging device 13 (Si substrate 20, wiring 31). Specifically, depending on the material of the wiring 31, etc., the semiconductor layer 6 is preferably formed at a film forming temperature or an annealing temperature of 400 ° C. or more, more preferably 350 ° C. or more, still more preferably 300 ° C. or more It is.

The gate electrode 71, the source / drain electrode 72, and the horizontal signal line and the vertical signal line are Al, Cu, Au, Ag, Pt, Pd, Fe, Co, Ni, Cr, Ti, W, Mo, V, Mn, It can be formed of a general metal electrode material such as a metal such as Ta or Ru or an alloy thereof, C (carbon) or the like. It is preferable that the electrodes 71 and 72, the signal lines, and the like have a shape and layout that do not block much light, such as designing the width small to the extent that the necessary conductivity can be ensured or providing the gap between adjacent pixels. . Alternatively, the electrodes 71 and 72, the signal lines and the like can be formed of the same transparent electrode material as the pixel electrodes 51 and 53 described above. The layout of the electrodes 71 and 72, the signal line and the like can be freely designed by applying a transparent electrode material which does not block light. However, when the temperature exceeds 300 ° C. in an oxidizing atmosphere such as air, the conductivity of ITO decreases. Therefore, it is preferable to apply SnO ₂ , FTO or the like, which is excellent in heat resistance among metal electrode materials or transparent electrode materials, to the gate electrode 71 etc. formed especially in front of the semiconductor layer 6.

The gate insulating film 86 is formed between the semiconductor layer 6 and the gate electrode 71. The insulating film 87 covers the semiconductor layer 6 as a channel protective film. The protective film 88 is an insulating film provided on the uppermost layer of the circuit layers 61 and 62, and contacts a predetermined area to electrically connect the circuit layers 61 and 62 and the pixel electrodes 51 and 53 thereon. A hole is formed. The gate insulating film 86, the insulating film 87, and the protective film 88 are formed at a temperature equal to or lower than the heat resistance temperature of the transparent substrate 91 and the third imaging element 13 as in the semiconductor layer 6 among the insulating materials applied to the TFT. Materials can be applied. Specifically, silicon nitride (Si ₃ N ₄ etc., expressed as SiN), silicon oxide (SiO ₂ ), silicon oxynitride (SiON), aluminum oxide (Al ₂ O ₃ ), magnesium oxide (MgO) And inorganic materials such as titanium oxide (TiO ₂ ), tantalum oxide, aluminum nitride, vanadium oxide, chromium oxide, cerium oxide, zinc oxide, and amorphous oxide (indium-gallium-zinc oxide).

(Protective film)
The protective films 81 and 82 are insulating films that constitute an interlayer film between the first imaging device 11 and the second imaging device 12 with these stacked two-layer films. Furthermore, when the protective films 81 and 82 are bonded and bonded to each other in the manufacturing process of the color imaging device 10, the first imaging device 11 and the second and third imaging devices 12 and 13, respectively, particularly the first circuit layer It is provided in order to suppress the impact to 61 and the 2nd circuit layer 62, or to protect. Further, the protective films 81 and 82 are planarizing films for making the surfaces of the protective films 81 and 82 flat, horizontal, and smooth. In the color imaging device 10 according to the present embodiment, the organic photoelectric conversion films 41 and 42 and the counter electrodes 52 and 54 thereon are formed to have a uniform film thickness, so the circuit layers 61 and 62 and the pixel electrode 51, Unevenness of the surface of the surface 53 (surface facing the organic photoelectric conversion films 41 and 42) is carried over to the surface of the counter electrodes 52 and 54. Therefore, the protective films 81 and 82 are formed to have an uneven thickness corresponding to the unevenness. The protective films 81 and 82 are formed on both sides of the opposing electrodes 52 and 54 of the organic photoelectric conversion films 41 and 42. Therefore, like the opposing electrodes 52 and 54, the insulating films can be formed at a low temperature of 150 ° C. or less. It is formed of a material. Specifically, inorganic materials such as SiO ₂ , SiN, Al ₂ O ₃ and TiO ₂ may be mentioned, and two or more of these materials may be laminated. Alternatively, it can be formed of a resin material that transmits light, such as polysilane, polyvinylcarbazole, polyimide, polyparaxylene vinylene, and the like. The protective films 81 and 82 are preferably thick in order to function as protective films, and specifically, the film thickness is preferably 0.1 μm or more. Furthermore, it is preferable that the protective films 81 and 82 have a minimum thickness of 1 μm or more when the films are formed and the surface is processed to be smooth by CMP (Chemical Mechanical Polishing) after film formation. On the other hand, in order to suppress the light receiving surface difference of the color imaging element 10, the maximum is preferably 3 μm or less, and more preferably 2 μm or less.

(Si substrate)
The Si substrate 20 is a material of the transistor 21 and the photodiode 23 constituting the transistors T1, T2, T3 and T4 of the third circuit portion 63, and is a base for forming these. In the present embodiment, since the transistor 21 is formed of a MOSFET (metal oxide semiconductor field effect transistor), the Si substrate 20 is preferably made of a single crystal silicon substrate. Here, the configuration of the photodiode 23 is used. Correspondingly, a p-type Si substrate (p-sub) is applied. Also, since the third imaging device 13 is a backside illuminated CMOS image sensor, the Si substrate 20 has the transistor 21 formed on the surface layer on the lower side (the side opposite to the light incident side), and is thick by grinding from the backside. The thickness is reduced to several micrometers to several tens of micrometers, and the ground back surface is directed upward.

(Photodiode)
The photodiode 23 is a buried photodiode formed in the Si substrate 20. Since Si has a wide spectral sensitivity including the visible region, the third imaging device 13 can photoelectrically convert light (L _B , L _G , L _R ) in any wavelength range. In the color image pickup device 10, the green light L _G and the blue light L _B is so absorbed in the organic photoelectric conversion film 41, the photodiode 23 receives light incident red light L _R. In order to receive the red light L _R , the photodiode 23 is formed in a region at a depth of at least about 3 μm from the upper surface (the interface with the interlayer film 84) of the Si substrate 20. In the present embodiment, in the p-type Si substrate 20, an n ^- epitaxial layer ("n-epi" in the figure, 20n) and a p ^- epitaxial layer ("p-epi", 20p) are sequentially stacked from the bottom. The photodiode 23 is formed of an np double epitaxial substrate. Further, in the Si substrate 20, ap well ("p-well" in the figure) 21p is formed in the n ^- epitaxial layer 20n so as to surround the pixel for each pixel. The photodiode 23 further includes an n ⁺ diffusion layer ("n ⁺ " in the figure) 23n covering an area surrounded by the p well 21p of the n ^- epitaxial layer 20n in the lower surface layer of the Si substrate 20, and n ⁺ diffusion. A p ⁺ diffusion layer ("p ⁺ " in the figure) 23p stacked on the layer 23n is provided. In addition, since the p ⁺ layer (“p-sub” in the figure) 20s of the Si substrate 20 is connected to GND as the anode of the photodiode 23, the upper surface of the Si substrate 20 at the peripheral portion of the color imaging device 10 An electrode (not shown) connected to the

(Third circuit unit)
The transistor 21 includes a p well 21 p formed on the Si substrate 20, an n ⁺ diffusion layer (“n ⁺ ” in the figure) 21 n formed in the p well 21 p, and a thin oxide film (gate It consists of a gate 21g which consists of a poly-Si film formed on both sides of an oxide film. Furthermore, in the p well 21 p, ap ⁺ diffusion layer (not shown) for electrically connecting the p well 21 p to GND (0 V) is formed. A wire 31 is connected to the gate 21 g, the n ⁺ diffusion layer 21 n, and the p ⁺ diffusion layer. Note that FIG. 2 shows a transistor formed of an n-type MOS (NMOS), which is a part of the third circuit unit 63. The p-type MOS (PMOS) forms an n-well (n-well) in the p-well 21p, and further forms ap ⁺ diffusion layer in this n-well to be a source and a drain of the transistor.

The wiring 31 includes a gate electrode and a source / drain electrode connected to the transistor 21, and a horizontal signal line and a vertical signal line of the third circuit portion 63 (the pixel selection line SL, the readout line OL, the reset selection line RL shown in FIG. The transfer selection line TL, V _DD power supply wiring, and V _RST power supply wiring are formed, and formed under the Si substrate 20. That is, since the wiring 31 is provided in the lowermost layer of the color imaging element 10, it is not necessary to transmit light. Therefore, the wiring 31 can be disposed in a desired area without restriction on the width and thickness and the number of layers. Such a wire 31 is generally made of a metal such as Al, Cu, Au, Ag, Pt, Pd, Fe, Co, Ni, Cr, Ti, W, Mo, V, Mn, Ta, Ru, or an alloy thereof. Metal electrode material. In particular, Al or Cu generally applied to the wiring of the semiconductor element is preferable, and a barrier film (barrier metal film) made of Ti, W or the like is further provided as needed. Here, the wiring 31 is made of Al or Al alloy which is relatively excellent in heat resistance and easy to process. With such a configuration, the heat resistance temperature of the third imaging device 13 is about 450 ° C., and the second circuit layer 62 (semiconductor layer 6) of the second imaging device 12 can be formed by a high temperature process.

The insulating film 83 covers the lower surface of the Si substrate 20 and insulates the wirings 31, the transistors 21, the wirings 31, and the like. As the insulating film 83, an insulating material applied to an interlayer insulating film of a semiconductor device can be applied. Specifically, inorganic materials such as SiO ₂ , SiN, SiON, Al ₂ O ₃ , MgO, MgF ₂ , SiC (silicon carbide) and the like can be mentioned. SiO ₂ also includes BPSG (Boron Phosphorus Silicon Glass) and PSG (Phosphorus Silicon Glass). The insulating film 83 may not be a single material, and may be formed of different materials depending on layers or regions.

(Interlayer film)
The interlayer film 84 is an insulating film provided between the second imaging device 12 and the third imaging device 13, that is, between the second circuit layer 62 and the Si substrate 20. The interlayer film 84 can be formed of the same inorganic insulating material as the insulating film 83 or the like so as to have heat resistance for forming the semiconductor layer 6 thereon. The interlayer film 84 preferably has a thickness of 2 μm or less, and more preferably 1 μm or less.

[Method of Manufacturing Color Image Sensor]
A method of manufacturing a color imaging device according to the first embodiment of the present invention will be described with reference to FIGS. 7 to 9, 2 and 6. FIG. The color imaging device 10 according to the present embodiment includes a first imaging device manufacturing process (upper imaging means forming process) S1 for manufacturing the first imaging device 11 (see FIG. 6) on a transparent substrate 91 and a Si substrate 20 as a first substrate. 3) After performing an imaging element laminate manufacturing step (imaging means lamination body forming step) S2 for manufacturing the imaging element 13 and the second imaging element 12 in a random order, a substrate bonding step S3 for bonding the substrates 20 and 91 Can be obtained by

(First imaging device manufacturing process)
The first imaging device manufacturing step S1 includes a first thin film transistor forming step S11 of forming a first circuit layer 61 of thin film transistors on a transparent substrate 91, and a first pixel electrode of forming a pixel electrode 51 in a predetermined area of a transparent electrode film. Forming step S12, first photoelectric conversion film forming step S13 for forming the first organic photoelectric conversion film 41, and first counter electrode for forming the counter electrode 52 by laminating the transparent electrode film on the first organic photoelectric conversion film 41 A film forming process S14 is performed, and further, a protective film 81 is formed on the counter electrode 52 to perform a protective film forming process S16 having a flat surface.

A first thin film transistor forming step S11 is performed. An electrode material is deposited on the transparent substrate 91, and the electrode film is processed to form horizontal signal lines such as the gate electrode 71 and the pixel selection line SL. An insulating film such as SiN is formed thereon to form a gate insulating film 86. An oxide semiconductor material is deposited and processed over the gate insulating film 86 to form the semiconductor layer 6. Further, an insulating film such as SiO ₂ constituting the insulating film 87 is formed, and the insulating film 87 and the gate insulating film 86 are processed. An electrode material is deposited and processed thereon to form vertical signal lines such as the source / drain electrodes 72 and the read lines OL. Further, an insulating film which constitutes the protective film 88 is formed to form a contact hole. The film formation method of each material applies a method corresponding to the material, such as a sputtering method, and the processing can be performed by photolithography and an etching or lift-off method. Moreover, the oxide semiconductor material which comprises the semiconductor layer 6 forms into a film at 300 degreeC or more, or performs annealing treatment at 300 degreeC or more after film-forming. The annealing treatment of the semiconductor layer 6 can be performed at any stage prior to the first photoelectric conversion film formation step S13, but when the treatment temperature exceeds the heat resistance temperature of the pixel electrode 51, the first pixel electrode formation is performed. It is performed before step S12. Furthermore, in the case of applying a transparent electrode material having a low heat resistance temperature to the source / drain electrode 72 and the like, annealing is performed prior to film formation of the transparent electrode material.

  A first pixel electrode forming step S12 is performed. A transparent electrode material is deposited on the first circuit layer 61, and the transparent electrode film is processed to form a pixel electrode 51. A transparent electrode material is formed into a film by well-known methods, such as a sputtering method, a vacuum evaporation method, or a coating method. Furthermore, in the case of a crystalline transparent electrode material such as ITO, post-annealing may be applied to form a film after film formation at a low temperature (no heating) such as room temperature. Further, processing of the transparent electrode film can be performed by photolithography and etching.

  Next, the first organic photoelectric conversion film 41 is formed by a known method such as a vacuum evaporation method, an inkjet method, a spin coating method, a dip method or the like (first photoelectric conversion film forming step S13). Further, a transparent electrode material is formed on the first organic photoelectric conversion film 41 to form an opposing electrode 52 (first opposing electrode film forming step S14). The transparent electrode material can be formed by sputtering or the like in the same manner as the first pixel electrode forming step S12, but it is performed at a low temperature (no heating) which does not exceed the heat resistance temperature of the first organic photoelectric conversion film 41, such as room temperature. .

Finally, a protective film forming step S16 is performed. An insulating film such as SiO ₂ is formed on the counter electrode 52 by plasma enhanced chemical vapor deposition (PECVD) or sputtering, etc., and planarized by CMP (chemical mechanical polishing) or the like, and further the substrate bonding step The surface is processed to a smooth surface corresponding to the bonding method in S3 to form a protective film 81. Alternatively, a resin material may be applied by spin coating or the like to form a protective film 81 on a flat surface.

(Image sensor stack manufacturing process)
In the imaging element laminate manufacturing step S2, the transistor 21 and the photodiode 23 are formed on the Si substrate 20, and the insulating film 83 between the wiring 31 and the wiring 31 is formed thereon. A second pixel electrode forming step S42 for forming the pixel electrode 53 in the second region, a second photoelectric conversion film forming step S43 for forming the second organic photoelectric conversion film 42, and a transparent electrode film as the second organic photoelectric conversion film 42 And forming a second counter electrode film forming step S44 of forming a counter electrode 54 by laminating. Here, the color imaging element 10 according to the present embodiment has a structure in which the second imaging element 12 and the third imaging element 13 are separated by the interlayer film 84 and divided into upper and lower parts, and the third imaging element 13. Is a backside illuminated CMOS image sensor. Therefore, in other words, the imaging element laminate manufacturing step S2 is a third imaging element manufacturing step (lower imaging means forming step) S20 for manufacturing the third imaging element 13 and a second imaging element for manufacturing the second imaging element 12 The manufacturing process S40 is performed. In the third imaging device manufacturing step S20, a silicon processing step S21 is performed, and then, a back surface grinding step S25 of grinding and thinning the back surface of the Si substrate 20; and an interlayer film 84 on the back surface of the Si substrate 20 An interlayer film forming step S26 is performed to form a film. In the second imaging device manufacturing step S40, first, after performing a second thin film transistor forming step S41 of forming a second circuit layer 62 of thin film transistors on the interlayer film 84, a second pixel electrode forming step S42 and a second photoelectric conversion A film forming step S43 and a second counter electrode film forming step S44 for forming the counter electrode 54 are performed, and a protective film 82 is further formed on the counter electrode 54 to form a protective film forming step S46. I do.

(Third imaging device manufacturing process)
For the third imaging device manufacturing step S20, a known manufacturing method of a backside illumination type CMOS image sensor can be applied (see, for example, Patent Document 2). First, in the silicon processing step S21, the transistor 21 and the photodiode 23 are formed on the Si substrate 20, and the wiring 31 connected to the transistor 21 is formed on the Si substrate 20. In the silicon processing step S21, each step is performed with the lower side in FIG. 2 as the upper side. the Si substrate 20 is a p-type Si substrate, p ^- epitaxial layer 20p, n ^- are sequentially forming an epitaxial layer 20n, and np double epitaxial substrate. Next, an impurity is injected from the surface (side of the n ⁻ epitaxial layer 20 n) of the Si substrate 20 and thermally diffused to form ap well 21 p in a predetermined region. A thin SiO ₂ film (gate oxide film) is formed on the surface of the Si substrate 20, and a poly-Si film is formed thereon to form the gate 21 g of the transistor 21. Further, impurities are implanted to form n ⁺ diffusion layers 21 n and 23 n and p ⁺ diffusion layer 23 p. An insulating film forming the insulating film 83 is formed on the Si substrate 20 on which the transistor 21 and the photodiode 23 are formed, a contact hole is formed in the insulating film, and the wiring 31 connected to the transistor 21 is Al or the like. It is formed of a metal electrode material. Similarly, film formation and processing of the insulating film and the metal electrode material are repeated to form the wiring 31 and the insulating film 83.

  Next, a support substrate (not shown) is bonded to the front side (on the insulating film 83) of the Si substrate 20, and the back surface of the Si substrate 20 is ground to a predetermined thickness (back surface grinding step S25). An insulating film is formed on the ground back surface of the Si substrate 20 to form an interlayer film 84 (interlayer film forming step S26).

(Second imaging element manufacturing process)
The second imaging element manufacturing step S40 is performed in the same manner as the first imaging element manufacturing step S1. That is, steps S41, S42, S43, S44, and S46 of the second imaging device manufacturing step S40 are the same as steps S11, S12, S13, S14, and S16 of the first imaging device manufacturing step S1, respectively. However, the second imaging element manufacturing step S40, particularly the second thin film transistor forming step S41, is performed under processing conditions that do not exceed the heat resistance temperature (for example, 450 ° C.) of the third imaging element 13.

(Substrate bonding process)
In the substrate bonding step S3, the transparent substrate 91 on which the first imaging device 11 is formed and the Si substrate 20 on which the imaging devices 12 and 13 are formed are on the side on which the opposing electrodes 52 and 54 are formed, that is, protection The membranes 81 and 82 face each other and are joined. The bonding method corresponds to the material of the protective films 81 and 82, and bonding is performed at a low temperature not exceeding the heat resistance temperature of the organic photoelectric conversion films 41 and 42, and at low pressure, preferably without pressure. As such a bonding method, a known method of bonding semiconductor element substrates at normal temperature can be applied, and specific examples thereof include bonding by atomic force and intermolecular force, surface activation bonding and the like. Alternatively, the color imaging device 10 may be fixed in a state in which the protective film 81 and the protective film 82 are in contact with each other by providing a frame (not shown) or the like on the peripheral edge or side of the upper and lower surfaces.

  At least one of the first organic photoelectric conversion film 41 and the counter electrode 52 of the first imaging device 11 and at least one of the second organic photoelectric conversion film 42 and the counter electrode 54 of the second imaging device 12 are respectively formed by spin coating or the like. When the film is formed and the surface is formed flat, there is no need to flatten the bonding surface with the protective films 81 and 82. The color imaging device 10 may have a gap of about 3 μm or less between the protective films 81 and 82 as long as the light receiving surface difference is suppressed to 10 μm or less. In such a color imaging device 10, in the substrate bonding step S3, a transparent substrate 91 and the Si substrate 20 are fixed by providing a frame (not shown) or the like on the peripheral edge or the side surface. Alternatively, an adhesive that transmits light may be attached to fill the space between the protective films 81 and 82. In these cases, since the protective film 81 and the protective film 82 do not contact each other in the substrate bonding step S3, damage to the circuit layers 61, 62 and the like is prevented even if the film thickness is formed thin, and the surface is It does not have to be flat.

  The pixel electrodes 51 and 53 may be integrally formed with the source and drain electrodes 72 of the circuit layers 61 and 62. In this case, the protective film 88 formed on these electrodes is processed so as to leave an area connected to the organic photoelectric conversion films 41 and 42 as the pixel electrodes 51 and 53.

  For miniaturization of pixels, each of the imaging elements 11, 12 and 13 is a part of the transistors T1, T2, T3 and T4 (see FIG. 4 and FIG. 5) or two or more predetermined numbers of adjacent pixels. You may share the whole thing. The third imaging device 13 may be a charge coupled device (CCD) image sensor.

  As described above, according to the color imaging device according to the first embodiment of the present invention, the first and second imaging devices other than the lowermost third imaging device are organic that are excellent in color selectivity and photoelectric conversion efficiency. A readout circuit having a photoelectric conversion film and having a TFT structure can be formed before the formation of the organic photoelectric conversion film, and the readout characteristics of the signal are improved and the distance between the imaging elements is short. A focus shift is suppressed. In addition, light of each wavelength range can be received in a desired order from the light incident side. And since only light of one wavelength region is incident on the third imaging device by the first and second imaging devices having the organic photoelectric conversion film, the photoelectric conversion layer is sensitive to at least this wavelength region. For example, Si having sensitivity to the entire visible light can be applied. The third imaging device is particularly excellent in signal readout characteristics by including the MOSFET formed on the single crystal silicon substrate in the readout circuit. Furthermore, according to the color imaging device according to the present embodiment, by making the third imaging device a back-illuminated CMOS image sensor, the aperture ratio of the pixels becomes high as in the first and second imaging devices.

Modification of First Embodiment
The third imaging device 13 may be a surface-illuminated CMOS image sensor. In this case, the transistors 21 formed on the surface layer of the Si substrate 20 are disposed at the same height position or near the light incident side with respect to the photodiode 23. Therefore, it is preferable to design the layout of the photodiode 23 and the transistor 21 so that the area (aperture ratio) of the photodiode 23 occupied in a pixel is increased. Further, since the wiring 31 is provided between the photodiode 23 (Si substrate 20) and the second imaging device 12, the wiring 31 is disposed so as not to be directly above the photodiode 23, and the number of layers is designed to be small. Is preferred. On the other hand, the wiring 31 is designed to be disposed over the entire region where the transistor 21 is formed, including the dummy wiring and the like in plan view, so that light does not reach the transistor 21. Therefore, the wiring 31 is preferably formed of Cu particularly excellent in conductivity. However, since the heat resistance temperature of the third imaging device 13 is about 350 ° C., the second imaging device manufacturing step S40 is performed under processing conditions that do not exceed this temperature. On the other hand, in the third imaging device manufacturing process S20, the back surface grinding process S25 and the interlayer film forming process S26 may not be performed, and the processes can be reduced.

  In the color imaging device 10 according to the first embodiment, the second circuit layer 62 of the second imaging device 12 is formed of a thin film transistor and provided on the third imaging device 13, and the second imaging device 12 and the third imaging device Although the structure 13 is divided by the interlayer film 84, the second circuit layer 62 can also be formed on the Si substrate in the same manner as the third circuit portion 63 of the third imaging device 13. Hereinafter, a color imaging device according to a modification of the first embodiment will be described. The same elements as those of the first embodiment are denoted by the same reference numerals, and the description thereof is omitted.

As shown in FIG. 10, a color imaging device 10A according to a modification of the first embodiment includes, in order from the top, a transparent substrate 91, a first circuit layer (first readout circuit) 61, and a first organic photoelectric conversion film ( A first image sensor 11 having a first photoelectric conversion layer 41, a second organic photoelectric conversion film (second photoelectric conversion layer) 42, wirings 31A and 32, and both surfaces of which are sandwiched between the counter electrode 54 and the pixel electrode 53 The semiconductor substrate 20A is provided with an insulating film 83 which insulates between the wirings 31A and 32 and a Si substrate 20A on which a photodiode (third photoelectric conversion layer) 23A is formed. The color imaging device 10A further includes a third circuit unit (third readout circuit) 63 and a second circuit unit (second readout circuit) 62A in the Si substrate 20A and the wirings 31A and 32. In FIG. 10, the upper part of the transparent substrate 91 is omitted. Further, in FIG. 10, the boundary between the pixels of the color imaging element 10A is indicated by an alternate long and short dash line. In the color imaging device 10A, the portion including the second organic photoelectric conversion film 42 and the second circuit portion 62A is a portion including the second imaging device 12A, the photodiode 23A, and the third circuit portion 63 a third imaging device 13A, It is called respectively. In this modification, light L1, L2, and L3 in the first, second, and third wavelength ranges are set to green light L _G , red light L _R , and blue light L _B , respectively. The second imaging device 12A and the third imaging device 13A are represented by the same equivalent circuit as the second imaging device 12 and the third imaging device 13 of the first embodiment (see FIGS. 3, 4 and 5). .

  The configuration of the first imaging element 11 is as described in the first embodiment. The second imaging element 12A includes, in order from the bottom, the pixel electrode 53, the second organic photoelectric conversion film 42, the counter electrode 54, and the protective film 82, and further includes a second circuit portion 62A under the pixel electrode 53. . The third imaging device 13A is a surface-illuminated CMOS image sensor, and has a Si substrate 20A formed on the surface layer of the photodiode 23A and the transistor 21 of the third circuit portion 63, and a wire 31A formed on the Si substrate 20A. An insulating film 83 is provided. Here, in the second imaging element 12A, the transistor 22 of the second circuit portion 62A is formed on the surface layer of the Si substrate 20A, and the wiring 32 is formed on the Si substrate 20A and connected to the pixel electrode 53. Accordingly, the color imaging device 10A according to the present modification has a structure in which the second imaging device 12A and the third imaging device 13A are not completely separated.

The second organic photoelectric conversion film 42 is as described in the first embodiment except that an organic material having sensitivity to red light L _R is applied. The second circuit unit 62A is a MOSFET formed on the Si substrate 20A in the same manner as the transistor 21 of the third circuit unit 63. Therefore, the second circuit unit 62A will be described together with the configuration of a third imaging device 13A described later.

(Si substrate)
The Si substrate 20A is a material of the transistor 22 of the second circuit portion 62A in addition to the photodiodes 23A and the transistor 21 of the third circuit portion 63, and is a base for forming these. In this modification, an n-type Si substrate (n-sub) is applied corresponding to the configuration of the photodiode 23A.

(Photodiode)
The photodiode 23A is a buried photodiode formed in the Si substrate 20A, and an n ⁺ diffusion layer (in the figure, “n ⁺ ”) formed in the p well 21p of the Si substrate 20A, and this n ⁺ diffusion layer And a p ⁺ diffusion layer (“p ⁺ ” in the figure) stacked on the In the color imaging device 10A, the green light L _G and the red light L _R is because it is absorbed by the organic photoelectric conversion film 41, the photodiode 23A is received blue light L _B. Therefore, the photodiode 23A is formed in a region about 300 nm deep from the upper surface of the Si substrate 20A. Further, since the third imaging element 13A is a surface-illuminated CMOS image sensor and the transistors 21 and 22 are formed on the surface layer of the Si substrate 20A near the light incident side, the area of the photodiode 23A occupied in pixels (aperture ratio Preferably, the layout of the photodiode 23A and the transistors 21 and 22 is designed to be large. In FIG. 10, the photodiode 23A and the transistors 21 and 22 are represented by the same size.

(Second circuit unit, third circuit unit)
As described in the first embodiment, the transistor 21 of the third circuit portion 63 includes the p well 21p formed on the Si substrate 20A, the n ⁺ diffusion layer 21n formed in the p well 21p, and the upper surface of the Si substrate 20A. And a gate 21g formed on both sides of the gate oxide film. A wire 31A is connected to the gate 21g and the n ⁺ diffusion layer 21n. The transistor 22 of the second circuit portion 62A is formed on the upper surface of the p well 22p formed on the Si substrate 20A, the n ⁺ diffusion layer 22n formed in the p well 22p, and the upper surface of the Si substrate 20A with a gate oxide film interposed. The gate 22g. A wire 32 is connected to the gate 22g and the n ⁺ diffusion layer 22n. Further, part of the wiring 32 penetrates the insulating film 83 in the thickness direction and is connected to the pixel electrode 53. Further, in the p wells 21p and 22p, p ⁺ diffusion layers (not shown) for electrically connecting the respective GNDs to the individual GNDs by the wirings 31A and 32 are formed. In FIG. 10, part of the transistors and wirings of the second circuit portion 62A and the third circuit portion 63 are shown.

  Similarly to the wiring 31 of the first embodiment, the wiring 31A constitutes an electrode connected to the transistor 21 and a horizontal signal line and a vertical signal line of the third circuit unit 63. The wiring 32 constitutes an electrode connected to the transistor 22, and horizontal signal lines and vertical signal lines of the second circuit portion 62A. The wiring 31A and the wiring 32 can be formed of a metal electrode material in the same manner as the wiring 31. However, the wires 31A and 32 are disposed on the upper side of the photodiode 23A, that is, on the light incident side. Therefore, the wirings 31A and 32 are disposed avoiding directly above the photodiode 23A so as not to block the light incident on the photodiode 23A. The wirings 31A and 32 are preferably designed to have a small number of layers so that the distance between the photodiode 23A and the second organic photoelectric conversion film 42 is not large, that is, the light receiving surface difference is not large. Therefore, the wirings 31A and 32 are preferably formed of Cu particularly excellent in conductivity. The wires 31A and 32 are designed to be disposed on the entire region where the transistors 21 and 22 are formed in plan view, including dummy wires and the like so that light does not reach the transistors 21 and 22 on the other hand .

(Method of manufacturing color imaging device)
A method of manufacturing a color imaging device according to a modification of the first embodiment of the present invention will be described with reference to FIGS. 7, 8, 11, and 10. FIG. As in the first embodiment, the color imaging device 10A according to the present modification includes the first imaging device manufacturing step S1 of manufacturing the first imaging device 11 (see FIG. 6) on the transparent substrate 91, and the Si substrate 20A. After the imaging element laminate manufacturing step S2 for manufacturing the third imaging element 13A and the second imaging element 12A is performed in random order, a substrate bonding step S3 for bonding the substrates 20A and 91 is obtained. The first imaging device manufacturing step S1 is as described in the first embodiment. Hereinafter, in the imaging element laminate manufacturing step S2, steps different from the first embodiment will be described in detail.

  As shown in FIG. 11, the imaging element laminate manufacturing step S2 includes a silicon processing step S21A, a second pixel electrode forming step S42, a second photoelectric conversion film forming step S43, and a second counter electrode film forming step S44. And a protective film forming step S46. In the silicon processing step S21A, as in the silicon processing step S21 (see FIG. 9) of the first embodiment, the transistor 21 and the photodiode 23A of the third circuit portion 63 are formed on the Si substrate 20A, and the wiring 31A is formed thereon. Although formed, in this modification, the transistor 22 and the wiring 32 of the second circuit portion 62A are further formed. Further, the portion of the wiring 32 connected to the pixel electrode 53 is exposed on the surface. Therefore, the silicon processing step S21A is a third imaging element manufacturing step (lower imaging means forming step) S20A for manufacturing the third imaging element 13A, and steps S21A, S42, S43, S44, S46, ie, imaging element laminate manufacturing step S2 Is the second imaging device manufacturing step S40A for manufacturing the second imaging device 12A. In other words, in the second imaging device manufacturing step S40A, the silicon processing step S21A is performed in place of the second thin film transistor forming step S41 in the second imaging device manufacturing step S40 of the first embodiment.

  The second pixel electrode forming step S42 is the same as the first embodiment except that a transparent electrode material is formed on the insulating film 83 where the wiring 32 is exposed for each pixel, and the subsequent steps S43, S44, S46 is also performed similarly to the first embodiment.

  The substrate bonding step S3 is the same as that of the first embodiment, and in this modification, the front side of the Si substrate 20A is the bonding surface.

  As described above, according to the color imaging device according to the modification of the first embodiment of the present invention, as in the first embodiment, the signal readout characteristics are improved and the shift of the incident light is suppressed. It is also possible to receive light of each wavelength range in a desired order from the light incident side. According to the color imaging device of the present modification, as in the third imaging device, the second imaging device further includes a MOSFET formed on a single crystal silicon substrate in the readout circuit, thereby improving the signal readout characteristics. Especially excellent. On the other hand, since the first imaging device has the readout circuit formed directly on the transparent substrate by a high temperature process, it has a good signal readout characteristic. In addition, by using the surface illumination type CMOS image sensor as the third imaging element, it is possible to manufacture more easily.

Second Embodiment
As described in the first embodiment, in the color imaging device according to the present invention, the first imaging device in the top layer and the other second and third imaging devices are manufactured separately and then joined. The first imaging device and the second imaging device formed on the respective bonding surfaces include both the organic photoelectric conversion film and the thin film transistor formed by the high temperature process. On the other hand, the lowermost third imaging element is provided with a Si photodiode as a photoelectric conversion layer in order to form a thin film transistor of the readout circuit of the second imaging element thereon. From this, by adding a heat-resistant photoelectric conversion layer to the lower side of the second imaging device, a color imaging device compatible with, for example, infrared (IR) light in addition to light in the three wavelength regions of visible light is can get. Hereinafter, a color imaging device according to the second embodiment will be described. The same elements as those of the first embodiment and the modification thereof are denoted by the same reference numerals, and the description thereof will be omitted.

As shown in FIG. 12, the color imaging device 10B according to the second embodiment includes, in order from the top, the transparent substrate 91, the first imaging device 11, the second imaging device 12, and the electric light L4 of the fourth wavelength range. And a third imaging element 13 that converts the image data into an image and outputs the converted image data. Therefore, the color imaging device 10B has a configuration in which the fourth imaging device 14 is inserted between the second imaging device 12 and the third imaging device 13 of the color imaging device 10 according to the first embodiment shown in FIG. The fourth imaging element 14 absorbs the light L4 in the fourth wavelength range to convert it into charges, and transmits the light L3 in the third wavelength range as an inorganic photoelectric conversion film (fourth photoelectric conversion layer) 44, And a fourth circuit layer (fourth readout circuit) 64 for outputting the charge as an electrical signal. Further, in the present embodiment, the organic photoelectric conversion films 41 and 42 of the imaging elements 11 and 12 further transmit the light L4 in the fourth wavelength range. In this embodiment, first, second, fourth, light L1 of the third wavelength region, L2, L4, and L3, respectively NIR L _IR (wavelength 750～900Nm), the green light L _G, the blue light L _B, and set to red light L _R. In FIG. 12, the lower part (a part of the third imaging element 13) of the color imaging element 10B is omitted. Further, in FIG. 12, the boundaries between the pixels of the color imaging element 10B are indicated by alternate long and short dashed lines.

The color imaging device 10B can include filters and microlenses on the transparent substrate 91 (not shown), as in the color imaging device 10 according to the first embodiment. However, the filter transmits near infrared light L _IR . The color imaging element 10B preferably has a short distance (length in the thickness direction) from the upper surface (the surface on the light incident side, the light receiving surface) of the first organic photoelectric conversion film 41 to the light receiving surface of the photodiode 23. In particular, for the second organic photoelectric conversion film 42 that receives visible light (light L _R , L _G , and L _B ), the inorganic photoelectric conversion film 44, and the photodiode 23, the photodiode is viewed from the upper surface of the second organic photoelectric conversion film 42. The distance to the upper surface of 23 is preferably 10 μm or less. Furthermore, the distance from the top surface of the first organic photoelectric conversion film 41 to the top surface of the photodiode 23 is more preferably 10 μm or less.

The configuration of each of the imaging elements 11, 12, and 13 is as described in the first embodiment. However, in the present embodiment, the first organic photoelectric conversion film 41 of the first imaging device 11 is made of an organic material having sensitivity to infrared light L _IR and transmitting visible light (L _B , L _G , L _R ). Ru. Examples of such organic materials include phenylene vinylene derivatives and squarylium derivatives. The second organic photoelectric conversion layer 42 of the second imaging element 12, an organic material sensitive to green light L _G is applied.

(4th imaging device)
The fourth imaging element 14 includes, in order from the bottom, the counter electrode 58, the inorganic photoelectric conversion film 44, the pixel electrode 57, the insulating film 89, the fourth circuit layer 64, and the interlayer film 85. Therefore, the fourth imaging device 14 has a configuration in which the stacking order of the fourth circuit layer 64 and the inorganic photoelectric conversion film 44 is switched with respect to the second imaging device 12. Any of these elements constituting the fourth imaging element 14 can be formed under processing conditions that do not exceed the heat resistance temperature (for example, 450 ° C.) of the third imaging element 13, and the heat resistance temperature is the second imaging element 12. In particular, the temperature is higher than the temperature at which the second circuit layer 62 is formed, specifically, 300 ° C., preferably 350 ° C. or higher. The fourth imaging device 14 is represented by the same equivalent circuit (see FIGS. 3 and 4) as the first and second imaging devices 11 and 12 of the first embodiment.

(Inorganic photoelectric conversion film)
The inorganic photoelectric conversion film 44 constitutes a photodiode PD (see FIGS. 3 and 4) in the pixel as a photoelectric conversion layer corresponding to the organic photoelectric conversion films 41 and 42 of the first and second imaging elements 11 and 12. As described above, the heat resistance temperature of the inorganic photoelectric conversion film 44 is higher than 300 ° C., preferably 350 ° C. or higher. Therefore, the inorganic photoelectric conversion film 44 is made of an inorganic material, but unlike an organic material, it absorbs all light of higher energy than light of a wavelength corresponding to its band gap (absorption end). That is, the inorganic photoelectric conversion film 44 has sensitivity to light in a specific wavelength range, absorbs it, converts it into charge, and transmits only light in a wavelength range longer than this. Therefore, the material of the inorganic photoelectric conversion film 44 so that the fourth imaging element 14 converts light of a shorter wavelength range than light L3 (red light L _R ) of the third wavelength range converted by the third imaging element 13 select, here selected to have a sensitivity to blue light L _B. Similar to the organic photoelectric conversion films 41 and 42, the inorganic photoelectric conversion film 44 preferably has a thickness of 50 nm or more and 1 μm or less.

  As such an inorganic material, a quantum composed of two or more elements selected from elements such as Cd, Se, S, Zn, As, In, P, Ga, Te, Si, etc., which are applied to solar cells etc. Dots can be mentioned, and the dot diameter is changed to adjust the absorption edge to any wavelength range of blue light, green light and red light.

In addition, amorphous silicon (hydrogenated amorphous silicon, a-Si: H) having sensitivity to blue light to green light and containing about several to 20 atomic% of hydrogen atoms can be applied. In the color image pickup device 10B, by the organic photoelectric conversion film 41 in the upper two layers, since the inorganic photoelectric conversion film 44 only the blue light L _B and the red light L _R is incident, according to such a material, inorganic photoelectric conversion film 44 absorbs the blue light L _B, photoelectric conversion, and transmits the red light L _R. Further, as an inorganic material having sensitivity to red light, amorphous silicon germanium (a-SiGe) can be given.

The pixel electrode 57 and the counter electrode 58 are a pair of electrodes connected to both sides of the inorganic photoelectric conversion film 44, and are similar to the pixel electrodes 51 and 53 and the counter electrodes 52 and 54 of the first and second imaging elements 11 and 12. It is a structure. Therefore, the pixel electrode 57 and the counter electrode 58 can be formed of the same transparent electrode material as the pixel electrodes 51 and 53. Furthermore, film formation can be performed by a process of high temperature (less than the heat resistance temperature of the inorganic photoelectric conversion film 44 and the third imaging element 13) for both the pixel electrode 57 and the counter electrode 58. When the temperature exceeds 300 ° C. in an oxidizing atmosphere such as the air, the conductivity of ITO decreases, and when it exceeds 350 ° C., sufficient conductivity can not be obtained. Therefore, the pixel electrode 57 and the counter electrode 58 contact with an exposed surface or an oxide film such as SiO _2, and the temperature of the semiconductor layer 6 of the fourth circuit layer 64 and the second circuit layer 62 exceeds 350.degree. When annealing or the like is performed, it is preferable to apply SnO ₂ , FTO, or the like excellent in heat resistance, or to stack an FTO film on a highly conductive ITO film.

  The insulating film 89 is provided under the fourth circuit layer 64, and further connects the pixel electrode 57 and the fourth circuit layer 64 thereunder through the contact holes. As the insulating film 89, the inorganic materials listed for the protective film 88 of the circuit layers 61 and 62 can be applied.

  The fourth circuit layer 64 has the same configuration as the circuit layers 61 and 62 (see FIG. 6). However, the fourth circuit layer 64 is provided on the upper side of the inorganic photoelectric conversion film 44. Therefore, in the fourth circuit layer 64, the pattern of the source / drain electrode 72 is designed to be connected to the lower pixel electrode 57 through the contact hole of the insulating film 89, while the uppermost protective film 88 is in contact No hole is formed.

  The interlayer film 85 is an insulating film provided between the second imaging device 12 and the fourth imaging device 14, that is, between the second circuit layer 62 and the fourth circuit layer 64. Furthermore, the interlayer film 85 is a planarizing film for flattening the formation surface of the second circuit layer 62 formed thereon. Therefore, the interlayer film 85 is formed to have an uneven thickness corresponding to the unevenness of the surface of the fourth circuit layer 64, similarly to the protective films 81 and 82 of the first and second imaging elements 11 and 12. The interlayer film 85 may be capable of forming a film at a temperature equal to or lower than the heat resistance temperature of the inorganic photoelectric conversion film 44 and the third imaging element 13, and on the other hand, the insulating film 89 and the insulating film 89 have the same heat resistance temperature as the inorganic photoelectric conversion film 44. Similarly, an inorganic material may be applied and two or more may be stacked. Alternatively, the interlayer film 85 may be integrally formed with the protective film 88 of the fourth circuit layer 64. The interlayer film 85 preferably has a maximum film thickness of 3 μm or less in total with the protective film 88, and more preferably 2 μm or less. The lower limit of the film thickness of the interlayer film 85 is not particularly limited, but in the case where the surface is processed to be smooth by CMP after film formation, the minimum is preferably 1 μm or more.

[Method of Manufacturing Color Image Sensor]
A method of manufacturing a color imaging device according to the second embodiment of the present invention will be described with reference to FIGS. 7, 8, 13 and 12. The color imaging device 10B according to the present embodiment includes a first imaging device manufacturing step S1 for manufacturing the first imaging device 11 (see FIG. 6) on the transparent substrate 91, and a third imaging device 13 and a fourth imaging device 13 for the Si substrate 20. After performing the imaging element laminate manufacturing step S2 of manufacturing the imaging element 14 and the second imaging element 12 in random order, a substrate bonding step S3 of bonding the substrates 20 and 91 is obtained. The first imaging device manufacturing step S1 and the substrate bonding step S3 are as described in the first embodiment. As shown in FIG. 13, the imaging element laminate manufacturing step S2 includes a third imaging element manufacturing step S20 for manufacturing the third imaging element 13 and a fourth imaging element manufacturing step S30 for manufacturing the fourth imaging element 14; A second imaging device manufacturing step S40 of manufacturing the second imaging device 12 is performed. That is, in the present embodiment, the fourth imaging element manufacturing step S30 is performed after the third imaging element manufacturing step S20 of the imaging element laminate manufacturing step S2 of the first embodiment shown in FIG. 9, and then the second imaging is performed. The element manufacturing process S40 is performed. The third imaging element manufacturing step S20 is as described in the first embodiment. Hereinafter, the fourth imaging element manufacturing step S30 will be described.

(Fourth imaging device manufacturing process)
In the fourth imaging element manufacturing step S30, a transparent electrode film is formed on the interlayer film 84 of the third imaging element 13 to form an opposing electrode 58, and the inorganic photoelectric conversion film 44 is formed. A fourth photoelectric conversion film formation step S32 to be formed, a fourth pixel electrode formation step S33 to form the pixel electrode 51 in a predetermined region with a transparent electrode film, and an insulation film deposition step S34 to form the insulation film 89; A fourth thin film transistor forming step S35 of forming a fourth circuit layer 64 by thin film transistors is performed, and further, an interlayer film 85 is formed on the fourth circuit layer 64 to perform a flattening step S36 of forming a flat surface.

  A transparent electrode material is formed on the interlayer film 84 to form an opposing electrode 58 (fourth opposing electrode film forming step S31). Next, the inorganic photoelectric conversion film 44 is formed on the counter electrode 58 (fourth photoelectric conversion film forming step S32). If the inorganic photoelectric conversion film 44 is a quantum dot, a colloidal dispersion is deposited by a solution thin film deposition method such as spin casting, and if it is a-Si: H, it is formed by a known method by a plasma CVD method. Membrane. Further, a transparent electrode material is formed on the inorganic photoelectric conversion film 44, and the transparent electrode film is processed to form a pixel electrode 57 (fourth pixel electrode forming step S33). The film formation and processing method of the transparent electrode film in steps S31 and S33 are the same as in the first pixel electrode formation step S12.

  Next, SiN or the like constituting the insulating film 89 is formed (insulating film forming step S34), and the fourth circuit layer 64 is formed on the insulating film 89 (fourth thin film transistor forming step S35). The fourth thin film transistor forming step S35 is the same as the first and second thin film transistor forming steps S11 and S41. However, the processing is performed under processing conditions that do not exceed the heat resistance temperatures of the third imaging element 13, the inorganic photoelectric conversion film 44, and the electrodes 57 and 58. Further, the insulating film 89 is processed together with the insulating film 87 and the gate insulating film 86 to form a contact hole on the pixel electrode 57. On the other hand, processing of the protective film 88 is unnecessary.

Finally, a planarization step S36 is performed. The planarization step S36 can be performed in the same manner as the protective film formation step S16. That is, an insulating film such as SiO ₂ is formed on the protective film 88 by plasma enhanced chemical vapor deposition (PECVD) or sputtering, and processed to a flat and smooth surface by CMP or the like to form the interlayer film 85. Do. Alternatively, a Si compound is applied and converted to SiO ₂ to form an interlayer film 85.

(Second imaging element manufacturing process)
The second imaging device manufacturing step S40 is as described in the first embodiment except that the second circuit layer 62 is formed on the interlayer film 85 of the fourth imaging device 14 in the second thin film transistor forming step S41. However, processing is performed under processing conditions that do not exceed the heat resistance temperatures of the third imaging device 13 and the fourth imaging device 14.

In the color imaging device 10B according to the present embodiment, the second imaging device 12 may convert the near infrared light L _IR . The first image sensor 11 or the second image sensor 12 may be converted to blue light L _B, in this case, the fourth image sensor 14 converts the green light L _G. Alternatively, the first imaging device 11 or the second imaging device 12 may convert red light L _R , in which case the fourth imaging device 14 emits blue light L _B and the third imaging device 13 emits green light. Convert L _G respectively.

  Similar to the second imaging device 12, the fourth imaging device 14 may include the fourth circuit layer 64 under the inorganic photoelectric conversion film 44. In this case, the fourth imaging device manufacturing step S30 has the same procedure as the second imaging device manufacturing step S40, and the fourth photoelectric conversion film forming step S32 is performed instead of the second photoelectric conversion film forming step S43.

  In the color imaging device 10B according to the present embodiment, the third imaging device 13 and the fourth imaging device 14 are respectively the third imaging device 13A of the color imaging device 10A (see FIG. 10) according to the modification of the first embodiment. And the same structure as that of the second imaging element 12A. Such a color imaging device 10B is replaced with the second photoelectric conversion film forming step S43 of the second imaging device manufacturing step S40A in the procedure shown in FIG. 11 in the imaging device laminate manufacturing step S2 to form a fourth photoelectric conversion film Step S32 is performed to form the third imaging device 13A and the fourth imaging device 14. Thereafter, a second imaging device manufacturing step S40 is performed to form the second imaging device 12 on the fourth imaging device 14.

  As described above, according to the color imaging device according to the second embodiment of the present invention, as in the first embodiment, the signal readout characteristic is improved, and the shift of the focal point of the incident light is suppressed. , And an infrared imaging device.

Third Embodiment
In the first and second embodiments, the lowermost third imaging device is provided with a Si photodiode as a photoelectric conversion layer, but any material having heat resistance may be used. For example, the fourth imaging device of the second embodiment An inorganic photoelectric conversion film can also be applied. The color imaging device according to the third embodiment will be described below. The same elements as those in the first and second embodiments are given the same reference numerals, and descriptions thereof will be omitted.

As shown in FIG. 14, the color imaging device 10C according to the third embodiment absorbs the light L3 in the third wavelength range by absorbing the transparent substrate 91, the first imaging device 11, the second imaging device 12, and the third wavelength range. An inorganic photoelectric conversion film (third photoelectric conversion layer) 43 for converting charges and a third imaging element 13B including a third circuit layer (third readout circuit) 63A, and a substrate 92 in order from the top, The photoelectric conversion film 43 is sandwiched between the counter electrode 56 and the pixel electrode 33 on the upper and lower surfaces. That is, the color imaging device 10C has a configuration in which the third imaging device 13 of the color imaging device 10 according to the first embodiment shown in FIG. 2 is replaced with a third imaging device 13B, and the first and second imaging devices 11 and 11 are used. The configuration of 12 is as described in the first embodiment. In FIG. 14, the boundaries between the pixels of the color imaging device 10C are indicated by alternate long and short dashed lines. In the present embodiment, the lights L1, L2, and L3 in the first, second, and third wavelength ranges are set to green light L _G , red light L _R , and blue light L _B , respectively.

(substrate)
The substrate 92 is a base for forming the third imaging device 13B and the second imaging device 12 thereon, and the third imaging device 13B is formed on the light incident side. The substrate 92 is formed of an insulating material having a heat resistant temperature for forming the third imaging device 13B, particularly the third circuit layer 63A. Specifically, a transparent substrate material similar to the transparent substrate 91, a Si substrate having a thermal oxide film formed on the surface, and the like can be mentioned.

(Third imaging device)
The third imaging device 13B includes, in order from the bottom, the third circuit layer 63A, the pixel electrode 33, the inorganic photoelectric conversion film 43, the counter electrode 56, and the interlayer film 84A. The heat resistance temperature of any of these elements constituting the third imaging device 13B is higher than the formation temperature of the second imaging device 12, particularly the second circuit layer 62, specifically more than 300 ° C., preferably 350 ° C. or more I assume. The third imaging device 13B has a configuration in which the stacking order of the fourth imaging device 14 of the color imaging device 10B according to the second embodiment is interchanged like the first and second imaging devices 11 and 12, and This is represented by the same equivalent circuit as the two imaging elements 11 and 12 (see FIGS. 3 and 4).

The inorganic photoelectric conversion film 43 absorbs and converts light L3 (blue light L _B ) of at least a third wavelength range from the same inorganic material as the inorganic photoelectric conversion film 44 of the color imaging device 10B according to the second embodiment. It does not have to be transparent as it is selected.

  The pixel electrode 33 and the counter electrode 56 are a pair of electrodes connected to both sides of the inorganic photoelectric conversion film 43. Like the pixel electrodes 51 and 53 of the first and second imaging elements 11 and 12, the pixel electrode 33 is formed in a pattern divided and separated for each pixel of the color imaging element 10C. However, since the pixel electrode 33 is connected to the lower surface of the inorganic photoelectric conversion film 43, it does not have to transmit light, and is formed of a metal electrode material like the wiring 31 of the color imaging device 10 according to the first embodiment. can do. The counter electrode 56 is a transparent electrode film formed on the entire surface with the same configuration as the counter electrode 58 of the color imaging device 10B according to the second embodiment, and has heat resistance and a high temperature (inorganic photoelectric conversion film 43 It is possible to form a film by the process of heat resistant temperature or less.

  The third circuit layer 63A has a thin film transistor (TFT) structure, similarly to the circuit layers 61 and 62 of the first and second imaging elements 11 and 12. However, since the third circuit layer 63A is provided below all the photoelectric conversion layers (organic photoelectric conversion films 41 and 42, inorganic photoelectric conversion film 43), light does not enter and does not have to be transmitted. . Therefore, the Si-based material can be applied to the third circuit layer 63A similarly to the third circuit portion 63 of the first embodiment, and as an example, polycrystalline silicon (poly-Si) exhibiting high electron mobility is used. The semiconductor layer 6A is provided. In the third circuit layer 63A, the gate electrode 71 is provided on the semiconductor layer 6A with the gate insulating film 86 interposed therebetween, and the insulating film 87 is further provided thereon. Further, like the pixel electrode 33, the gate electrode 71, the source / drain electrode 72, and the horizontal signal line and the vertical signal line are preferably formed of a metal electrode material.

  The interlayer film 84A is an insulating film provided between the second imaging element 12 and the third imaging element 13B, that is, between the second circuit layer 62 and the counter electrode 56. Furthermore, the interlayer film 84A is a planarization film for flattening the formation surface of the second circuit layer 62 formed thereon. Therefore, the interlayer film 84A has the same configuration as the interlayer film 85 of the color imaging device 10B according to the second embodiment.

[Method of Manufacturing Color Image Sensor]
A method of manufacturing a color imaging device according to the third embodiment of the present invention will be described with reference to FIGS. 7, 8, 15, and 14. FIG. The color imaging device 10C according to the present embodiment includes a first imaging device manufacturing step S1 for manufacturing the first imaging device 11 (see FIG. 6) on the transparent substrate 91, and a third imaging on the substrate (lower substrate) 92. The image pickup device laminate manufacturing step S2 of manufacturing the element 13B and the second image pickup device 12 is performed in random order, and then the substrate bonding step S3 of bonding the substrates 91 and 92 is performed. The first imaging device manufacturing step S1 and the substrate bonding step S3 are as described in the first embodiment. As shown in FIG. 15, in the imaging element laminate manufacturing step S2, a third imaging element manufacturing step (lower imaging means forming step) S20B for manufacturing the third imaging element 13B and a second one for manufacturing the second imaging element 12 An imaging element manufacturing process S40 is performed. The second imaging element manufacturing step S40 is as described in the first embodiment. Hereinafter, the third imaging element manufacturing step S20B will be described.

(Third imaging device manufacturing process)
The third imaging device manufacturing step S20B includes a third thin film transistor forming step S21B of forming a third circuit layer 63A of thin film transistors on a substrate 92, and forming a third pixel electrode of forming a pixel electrode 33 in a predetermined region of metal electrode material. Step S22, third photoelectric conversion film forming step S23 for forming the inorganic photoelectric conversion film 43, and third counter electrode film forming step S24 for forming the counter electrode 56 by laminating the transparent electrode film on the inorganic photoelectric conversion film 43 , And an interlayer film 84A is formed on the counter electrode 56 to perform a planarization step S26A for forming a flat surface.

  The third thin film transistor formation step S21B is performed. Amorphous Si (a-Si) is deposited on the substrate 92 by the CVD method or the like, and the a-Si film is crystallized into poly-Si by annealing at about 600 ° C. The poly-Si film is processed to form the semiconductor layer 6A. A gate insulating film 86 is formed thereon. A metal electrode material is deposited and processed on the gate insulating film 86 to form horizontal signal lines such as the gate electrode 71 and the pixel selection line SL. Impurities are implanted into the semiconductor layer 6A from above. Next, an insulating film forming the insulating film 87 is formed, and a contact hole is formed in the insulating film 87 or further in the gate insulating film 86. A metal electrode material is deposited and processed thereon to form vertical signal lines such as the source / drain electrodes 72 and the read lines OL. Further, an insulating film which constitutes the protective film 88 is formed to form a contact hole.

  A metal electrode material is film-formed and processed on the third circuit layer 63A to form the pixel electrode 33 (third pixel electrode forming step S22). Then, the inorganic photoelectric conversion film 43 is formed (third photoelectric conversion film forming step S23), and a transparent electrode film is further stacked thereon to form the counter electrode 56 (third counter electrode film forming step S24). Finally, an interlayer film 84A is formed on the counter electrode 56 (planarization step S26A). These steps S23, S24 and S26A are respectively the fourth photoelectric conversion film forming step S32, the fourth opposing electrode film forming step S31, and the flattening step S36 of the fourth imaging element manufacturing step S30 of the second embodiment (see FIG. 13). Can be done in the same way as

(Modification)
The third imaging element 13B may be planarized before the formation of the inorganic photoelectric conversion film 43, and the protective film 88 of the third circuit layer 63A can be used as a planarizing film. Specifically, in the third thin film transistor formation step S21B, SiO ₂ or the like constituting the protective film 88 is formed to a sufficient thickness (for example, a film thickness of more than 1 μm) with respect to the step of the third circuit layer 63A. After the surface is ground to a predetermined thickness and a flat surface, contact holes are formed. By forming the pixel electrode 33 thereon, the difference in level on the surface of the third imaging element 13B is only due to the film thickness of the pixel electrode 33 in the gap between adjacent pixels and that due to the contact hole of the protective film 88. . Therefore, the surface of the interlayer film 84A does not have to be planarized, and the film thickness can be reduced to reduce the light receiving surface difference of the color imaging element 10C. It is preferable that the transistor (semiconductor layer 6) of the second circuit layer 62 of the second imaging element 12 be disposed in a region without steps.

  Similar to the circuit layers 61 and 62, the third circuit layer 63A may have a TFT structure (see FIG. 6) that transmits light provided with the semiconductor layer 6 made of an oxide semiconductor. In this case, the third circuit layer 63A may be provided on the inorganic photoelectric conversion film 43. Such a third imaging device 13B has a structure similar to that of the fourth imaging device 14 of the color imaging device 10B (see FIG. 12) according to the second embodiment, and a transparent electrode film is formed on the upper surface of the inorganic photoelectric conversion film 43 An electrode 33 is formed. On the other hand, the counter electrode 56 connected to the lower surface of the inorganic photoelectric conversion film 43 can be formed of a metal electrode film.

Furthermore, when the third circuit layer 63A is provided on the inorganic photoelectric conversion film 43 as described above, a material formed at a high temperature (for example, 500 ° C. or higher) can be applied to the inorganic photoelectric conversion film 43. Specifically, Cu and, In, and at least one Ga, S, compounds of the chalcopyrite structure composition _{CuIn 1-x Ga x (Se} 1-y S y) containing at least one Se semiconductor (CIGS) membranes, which are sensitive to the whole visible range and to near infrared radiation. Furthermore, it is preferable that the inorganic photoelectric conversion film 43 has gallium oxide (Ga ₂ O ₃ ) laminated as a hole injection blocking layer on the CIGS film. In addition, a high melting point metal such as Mo is applied to the counter electrode 56 connected to the lower surface of the inorganic photoelectric conversion film 43.

  Similar to the first and second embodiments, the third imaging device 13B can also be configured to include a third circuit unit 63 having a transistor 21 formed of a MOSFET formed on a Si substrate. In this case, the third imaging device 13B has the same structure as the second imaging device 12A of the color imaging device 10A (see FIG. 10) according to the modification of the first embodiment, and the wiring 31A formed on the Si substrate 20A. Thus, the pixel electrode 33 is connected to the transistor 21.

Similar to the second embodiment, the color imaging device 10C may have the infrared imaging device mounted by inserting the fourth imaging device 14 between the second imaging device 12 and the third imaging device 13B. . Further, at this time, a CIGS film is applied to the inorganic photoelectric conversion film 43, and the light L3 in the third wavelength range is set to the near infrared light L _IR, and the light L1, L2 in the first, second, and fourth wavelength ranges is set. , L 4 can also be set to visible light (L _B , L _G , L _R ).

  As described above, according to the color imaging device of the third embodiment of the present invention, as in the first embodiment, the readout characteristics of the signal are improved, and the shift of the focal point of the incident light is suppressed. In the lowermost third imaging device, the aperture ratio of the pixels is increased similarly to the first and second imaging devices, and amorphous silicon or the like having higher absorption efficiency than crystalline silicon is applied to the photoelectric conversion layer. Can be made thinner. In addition, by applying the TFT structure to the readout circuit of the third imaging element, the thickness can be further reduced.

  Although the embodiments for carrying out the color imaging device and the method for manufacturing the same according to the present invention have been described above, the present invention is not limited to these embodiments, and various modifications may be made within the scope of the claims. Changes are possible.

10, 10A, 10B, 10C Color imaging device 11 1st imaging device 12, 12A 2nd imaging device 13, 13A, 13B 3rd imaging device 20, 20A Si substrate (lower substrate)
21, 22 transistors 23, 23 A photodiode (third photoelectric conversion layer)
31, 31A wiring 32 wiring 33 pixel electrode 41 first organic photoelectric conversion film (first photoelectric conversion layer)
42 Second organic photoelectric conversion film (second photoelectric conversion layer)
43 Inorganic photoelectric conversion film (third photoelectric conversion layer)
44 Inorganic photoelectric conversion film (fourth photoelectric conversion layer)
51, 53, 57 pixel electrode 52, 54, 56, 58 counter electrode 61 first circuit layer (first readout circuit)
62 Second Circuit Layer (Second Readout Circuit)
62A Second Circuit Unit (Second Readout Circuit)
63 Third Circuit Unit (Third Readout Circuit)
63A Third Circuit Layer (Third Readout Circuit)
64 Fourth Circuit Layer (Fourth Readout Circuit)
Reference Signs List 6 semiconductor layer 71 gate electrode 72 source electrode, drain electrode 81, 82 protective film 83 insulating film 84, 84 A interlayer film 85 interlayer film 86 gate insulating film 87 insulating film 88 protective film 89 insulating film 91 transparent substrate 92 substrate (lower substrate )
S1 First imaging device manufacturing process (upper imaging means forming process)
S2 Image pickup element laminate manufacturing process (image pickup means laminate forming process)
S3 Substrate bonding process S11 First thin film transistor formation process S12 First pixel electrode formation process S13 First photoelectric conversion layer formation process S14 First opposing electrode film formation process S20, S20A, S20B Third imaging device manufacturing process (lower imaging means formation process )
S21, S21A Silicon Processing Step S21B Third Thin Film Transistor Forming Step S22 Third Pixel Electrode Forming Step S23 Third Photoelectric Conversion Layer Forming Step S24 Third Counter Electrode Film Forming Step S25 Back Surface Grinding Step S30 Fourth Image Pickup Element Manufacturing Step S31 Fourth Opposite Electrode film forming process S32 fourth photoelectric conversion layer forming process S33 fourth pixel electrode forming process S35 fourth thin film transistor forming process S40, S40A second imaging element manufacturing process S41 second thin film transistor forming process S42 second pixel electrode forming process S43 second Photoelectric conversion layer formation process S44 second counter electrode film formation process

Claims (6)

A first photoelectric conversion layer that absorbs light in a first wavelength range and converts it into charges, and transmits light in a second wavelength range and a third wavelength range; and light in the second wavelength range A second photoelectric conversion layer that absorbs light and converts it into charges, and transmits light in the third wavelength range, and absorbs light in the third wavelength range and converts it into charges in at least a part of the area A color imaging device comprising, in order from the top, a third photoelectric conversion layer, and in which light including a plurality of wavelength ranges is incident from above,
A first readout circuit provided with a thin film transistor and outputting electric charge converted by the first photoelectric conversion layer as an electric signal is provided above the first photoelectric conversion layer,
A second readout circuit for outputting the charge converted by the second photoelectric conversion layer as an electric signal, and a third readout circuit for outputting the electric charge converted by the third photoelectric conversion layer as an electric signal; Below the second photoelectric conversion layer,
A color image pickup device characterized in that each of the first photoelectric conversion layer and the second photoelectric conversion layer contains an organic material, and both surfaces thereof are sandwiched by transparent electrode films.   The color imaging device according to claim 1, wherein the third readout circuit includes crystalline silicon.   The color imaging device according to claim 2, wherein the third photoelectric conversion layer contains crystalline silicon.   The color imaging device according to any one of claims 1 to 3, wherein the second readout circuit includes a thin film transistor, and is provided above the third photoelectric conversion layer. . A fourth photoelectric conversion layer that absorbs light in a fourth wavelength range and converts it into charges and transmits light in the third wavelength range comprises the second readout circuit and the third photoelectric conversion layer. Between the second photoelectric conversion layer and the fourth readout circuit for outputting the electric charge as an electric signal,
The color imaging device according to claim 4, wherein the first photoelectric conversion layer and the second photoelectric conversion layer transmit light in the fourth wavelength range. An imaging means laminate forming step of forming on the lower substrate an imaging means for converting light of two or more wavelength bands into an electric signal for each wavelength band and outputting the light, and light of a wavelength band different from the two or more wavelength bands Upper imaging means forming step of forming an imaging means on the transparent substrate by converting it into an electric signal and outputting the same, and then performing a substrate bonding step of bonding the lower substrate and the transparent substrate in random order A method of manufacturing an imaging device,
The upper imaging means forming step includes a first thin film transistor forming step of forming a thin film transistor on the transparent substrate, a first pixel electrode forming step of forming a transparent electrode film in a predetermined region, and a first forming a photoelectric conversion layer. Performing a photoelectric conversion layer forming step and a first counter electrode film forming step of laminating a transparent electrode film on the photoelectric conversion layer,
The imaging means laminate formation step includes a lower imaging means formation step of forming a transistor and a photoelectric conversion layer on the lower substrate, a second pixel electrode formation step of forming a transparent electrode film in a predetermined region, and the transparent electrode Performing a second photoelectric conversion layer forming step of forming a photoelectric conversion layer on the side on which the film is formed, and a second counter electrode film forming step of laminating a transparent electrode film on the photoelectric conversion layer,
In the substrate bonding step, the lower substrate and the side of the transparent substrate on which the transparent electrode film is formed are faced to each other for bonding.
Heat treatment is performed before at least one of the first photoelectric conversion layer forming step in the upper imaging means forming step and the second photoelectric conversion layer forming step in the imaging means laminate forming step. Method of manufacturing a color imaging device.