JP2007043534A - Image sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image sensor excellent in reliability capable of reading information at high SN ratio, by disposing a photoelectric conversion device considering the dispersion of the sensing characteristic thereof to a drive circuit formed of silicon transistors. <P>SOLUTION: When a maximum illuminance incident on each photoelectric conversion device 3 provided for each color R, G, B, is set to I (lux), and the sensitivity of each photoelectric conversion device 3 for each color R, G, B, is set to α (volt/lux time); each photoelectric conversion device 3 is disposed to have such a structure that the wiring distance to a drive circuit is made shorter for the photoelectric conversion device 3 having a smaller product of I and α. Since a signal charge from each photoelectric conversion device 3 for each color can be sensed at high SN ratio, even when there is dispersion in the sensitivity characteristic for each color R, G, B; the image sensor has effects capable of a high-speed operation with high quality, and excellent in reliability and practicality. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an image sensor that extracts various information such as an object shape and an image as an electrical signal.

  As an image sensor in a facsimile, a scanner, or the like, a contact type linear sensor that uses only a rod lens as an optical system and can be easily miniaturized is used. This close contact type linear sensor has a sensor length equivalent to that of a document, and is configured by arranging a plurality of CMOS sensor chips and CCD sensor chips formed of single crystal silicon.

In recent years, a technique capable of forming a photoelectric conversion element by a very simple method using an organic material has been developed (for example, Patent Document 1).
Special Table 2002-502120

  However, the above conventional techniques have the following problems.

  (1) In the case of a conventional close contact type linear sensor using a CMOS sensor chip or a CCD sensor chip formed of single crystal silicon, it is necessary to arrange a plurality of chips with high accuracy, and a portion corresponding to a joint between the chips. There was a problem that the information could not be read accurately.

  (2) If a photoelectric conversion element is formed using an organic material like the organic semiconductor image sensor of (Patent Document 1), a photoelectric conversion element array having a predetermined size and a predetermined resolution is formed by a very simple method. Therefore, although the above problem (1) can be solved, the photoelectric conversion element using the organic material has a problem that the sensitivity characteristics of each color are biased.

  Furthermore, the drive circuit that detects the signal charge from the photoelectric conversion element and reads it out is formed of a silicon transistor, and its manufacturing process is different from that of the photoelectric conversion element, so it is placed at a distance from the photoelectric conversion element. Therefore, as the wiring distance connecting between them increases, the capacity increases and the signal charge from the photoelectric conversion element decreases, and there is a problem that the signal charge cannot be detected accurately. In particular, when the resolution of the photoelectric conversion element is 600 DPI or more, the capacitance of the photoelectric conversion element itself becomes extremely small, so that a change in capacitance due to a difference in wiring distance cannot be ignored.

  SUMMARY OF THE INVENTION The present invention solves the above-described problem. Information is read with a high S / N ratio by arranging photoelectric conversion elements in consideration of the influence of variations in sensitivity characteristics in a drive circuit formed of silicon transistors. An object of the present invention is to provide an image sensor with excellent reliability that can be used.

  In order to solve the above problems, an image sensor of the present invention includes a photoelectric conversion element formed of an organic compound layer sandwiched between an anode and a cathode, and a silicon transistor formed of at least the photoelectric conversion layer. An image sensor comprising a detection circuit that detects an output due to signal charges accumulated in an element and a read circuit that reads out the signal charges, wherein the photoelectric conversion of each color of R, G, and B When the maximum illuminance incident on the element is I (lux) and the sensitivity of the photoelectric conversion element of each color of R, G, B is α [volt / (lux · time)], the photoelectric conversion element of each color In this configuration, the driving circuit is arranged in order from the smallest product of I and α.

  As a result, even if there are variations in sensitivity characteristics for each color of R, G, and B, the signal charge from the photoelectric conversion element of each color can be detected with a high S / N ratio, so that information can be read reliably even in a short accumulation time. Therefore, it is possible to provide an image sensor excellent in reliability and practicality capable of high-quality and high-speed operation.

  In order to solve the above problems, an image sensor of the present invention includes a photoelectric conversion element formed of an organic compound layer sandwiched between an anode and a cathode, and a silicon transistor formed of at least the photoelectric conversion layer. An image sensor comprising a detection circuit that detects an output due to signal charges accumulated in an element and a read circuit that reads out the signal charges, wherein the photoelectric conversion of each color of R, G, and B Among the elements, the photoelectric conversion element for R light is arranged at a position closest to the drive circuit.

  As a result, even if the signal charge from the photoelectric conversion element of R light, which is generally insensitive, is small, the influence of the capacitance of the wiring can be suppressed, and the signal charge can be reliably detected with a high S / N ratio in the drive circuit. Therefore, it is possible to provide an image sensor excellent in reliability and practicality.

  As described above, according to the image sensor of the present invention, the following advantageous effects can be obtained.

According to the invention of claim 1,
(1) In a photoelectric conversion element of each color of R, G, and B, the smaller the product of the incident maximum illuminance I (lux) and the sensitivity α [volt / (lux · time)], By arranging the wiring distance to be short, it is possible to reduce the influence of the capacitance of the wiring on the photoelectric conversion element of a color having poor sensitivity characteristics, and to ensure the signal charge from the photoelectric conversion element of each color with a high SN ratio. An image sensor with excellent reliability that can be detected can be provided.

  (2) In the photoelectric conversion element of each color of R, G, B, the smaller the product of the incident maximum illuminance I (lux) and the sensitivity α [volt / (lux · time)], By arranging the wiring distance to be short, variations in the sensitivity characteristics between the photoelectric conversion elements of each color can be absorbed by the difference in wiring distance, and the signal charge from the photoelectric conversion elements of each color can be detected in a short time. It is possible to provide an image sensor excellent in practicality capable of high-quality and high-speed operation.

According to invention of Claim 2,
(1) Among the photoelectric conversion elements of each color of R, G, and B, the wiring capacitance is generally reduced by arranging the wiring distance between the photoelectric conversion element of R light having low sensitivity and the drive circuit to be the shortest. Therefore, it is possible to provide an image sensor excellent in reliability and practicality that can reliably detect a signal charge with a high S / N ratio in a drive circuit.

According to invention of Claim 3, in addition to the effect of Claim 1 or 2,
(1) When a silicon transistor is formed of single crystal silicon, it has high mobility and can operate at high speed, and also has small threshold variation and excellent ability uniformity, reducing variation in quality within and between individuals. Therefore, it is possible to provide an image sensor excellent in reliability and practicality.

  (2) When the silicon transistor is formed of polycrystalline silicon or amorphous silicon, the photoelectric conversion element and the drive circuit can be formed on the same glass substrate, so that it is not necessary to mount on a chip and is inexpensive and excellent in mass productivity. It is possible to provide an image sensor excellent in reliability and practicality that can reduce the wiring capacity by reducing the wiring distance and can reliably detect the signal charge with a high SN ratio.

  The present invention is excellent in reliability that information can be read with a high S / N ratio by arranging photoelectric conversion elements in consideration of the influence of variations in sensitivity characteristics for a drive circuit formed of silicon transistors. For the purpose of providing an image sensor, the maximum illuminance I (lux) incident on photoelectric conversion elements of R, G, and B colors and the sensitivity α [volt / () of the photoelectric conversion elements of R, G, and B colors. (Lux / Time)] in order from the smallest product to the drive circuit.

  The present invention is excellent in reliability that information can be read with a high S / N ratio by arranging photoelectric conversion elements in consideration of the influence of variations in sensitivity characteristics for a drive circuit formed of silicon transistors. The object of providing an image sensor was realized by arranging the R light photoelectric conversion element in the position closest to the drive circuit among the R, G, B color photoelectric conversion elements.

  A first invention made to solve the above-described problem is that a photoelectric conversion layer formed of an organic compound layer is sandwiched between an anode and a cathode, and a silicon transistor is used to form at least a photoelectric conversion. An image sensor including a detection circuit that detects an output due to signal charges accumulated in an element, and a read circuit that reads out signal charges. The image sensor includes photoelectric conversion elements of R, G, and B colors. When the maximum illuminance incident is I (lux) and the sensitivity of each color photoelectric conversion element of R, G, and B is α [volt / (lux · time)], among the photoelectric conversion elements of each color, I and It has a configuration in which the product is arranged at a position closer to the drive circuit in ascending order of product with α.

  This configuration has the following effects.

  (1) In a photoelectric conversion element of each color of R, G, and B, the smaller the product of the incident maximum illuminance I (lux) and the sensitivity α [volt / (lux · time)], By arranging the wiring distance to be short, it is possible to reduce the influence of the capacitance of the wiring on the photoelectric conversion element of a color having poor sensitivity characteristics, and to ensure the signal charge from the photoelectric conversion element of each color with a high SN ratio. Can be detected.

  (2) In the photoelectric conversion element of each color of R, G, B, the smaller the product of the incident maximum illuminance I (lux) and the sensitivity α [volt / (lux · time)], By arranging the wiring distance to be short, variations in the sensitivity characteristics between the photoelectric conversion elements of each color can be absorbed by the difference in wiring distance, and the signal charge from the photoelectric conversion elements of each color can be detected in a short time. .

  As a method for producing the photoelectric conversion layer of the photoelectric conversion element, any method can be used as long as it can stably produce a thin film having high uniformity and smoothness, and various vacuum methods such as vacuum deposition and sputtering. Processes, wet processes such as spin coating, dipping method, and ink jet method are preferably used. It is possible to select any process according to the material, configuration, etc., but it is excellent in mass productivity and low cost when a photoelectric conversion layer is formed by a wet process that does not require a large-scale manufacturing apparatus. .

  Although there are variations in the sensitivity characteristics of photoelectric conversion elements formed of organic materials, each color photoelectric conversion element is considered by considering both maximum illuminance I (lux) and sensitivity α [volt / (lux · time)]. The arrangement according to the sensitivity characteristic can be performed. A photoelectric conversion element with a small product of maximum illuminance I and sensitivity α has a small amount of change in potential due to signal charge, so it can be placed close to the input terminal of the drive circuit to shorten the wiring distance. It is possible to suppress the influence of the capacity accompanying the.

  A second invention made to solve the above-described problem is that a photoelectric conversion layer formed of an organic compound layer is sandwiched between an anode and a cathode, and a silicon transistor is used to form at least a photoelectric conversion. An image sensor comprising: a detection circuit that detects an output due to signal charges accumulated in an element; and a drive circuit that includes a read-out means that reads out signal charges, and each of the photoelectric conversion elements of R, G, and B colors Among them, the photoelectric conversion element for R light has a configuration arranged at a position closest to the drive circuit.

  (1) Among the photoelectric conversion elements of each color of R, G, and B, the wiring capacitance is generally reduced by arranging the wiring distance between the photoelectric conversion element of R light having low sensitivity and the drive circuit to be the shortest. The signal charge can be reliably detected with a high S / N ratio in the drive circuit.

  A third invention made to solve the above problems is the image sensor according to the first or second invention, wherein the silicon transistor is one of single crystal silicon, polycrystalline silicon, and amorphous silicon. 1 is formed.

  With this configuration, in addition to the operation of the first or second invention, the following operation is provided.

  (1) By forming the silicon transistor from single crystal silicon, high mobility is possible and high-speed operation is possible, and variation in threshold can be reduced, resulting in excellent uniformity.

  (2) By forming the silicon transistor from polycrystalline silicon or amorphous silicon, it is not necessary to mount the chip, and it is inexpensive and excellent in mass productivity.

(Embodiment 1)
Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a plan view showing an image sensor according to Embodiment 1 of the present invention, FIG. 2 is a plan view showing the arrangement of photoelectric conversion elements and drive circuits of the image sensor according to Embodiment 1 of the present invention, and FIG. It is sectional drawing which shows the structure of the photoelectric conversion element of the image sensor in Embodiment 1 of invention.

  In FIG. 1, 1 is an image sensor according to the first embodiment of the present invention, 2 is a glass substrate as a substrate of the image sensor 1, 3 is a photoelectric conversion element of the image sensor 1 formed of an organic material, and 4 is single crystal silicon. IC chip 5 on which the drive circuit formed in (5) is mounted is a wiring for connecting each photoelectric conversion element 2 and IC chip 4.

  In FIG. 2, R1, R2, R3,..., G1, G2, G3,..., B1, B2, B3,. It shows that B light is photoelectrically converted, and photoelectric conversion elements 3 are arranged in a row for each of R, G, and B colors.

  A wiring 5 that connects the photoelectric conversion elements 3 of each color and an input terminal (not shown) of the driving circuit of the IC chip 4 is a photoelectric conversion element 3 (R1, R2, R3,...) That photoelectrically converts R light. Of the photoelectric conversion elements 3 (B1, B2, B3,...) That photoelectrically convert B light is the longest.

With respect to this arrangement, the maximum illuminance incident on the photoelectric conversion element 3 is I, the sensitivity is α, and the colors of light that the photoelectric conversion elements 3 of R, G, and B colors perform photoelectric conversion are subscripts R, G, and B, respectively. When the maximum illuminance I _R , I _G , I _{B of} each color and the sensitivity α _R , α _G , α _B are
I _R × α _R ≦ I _G × α _G ≦ I _B × α _B (Equation 1)
In order to hold this relationship, they are arranged in this way. Thereby, the dispersion | variation in the sensitivity characteristic of the photoelectric conversion element 3 formed with the organic material can be reduced. Further, in this (Equation 1), when the maximum illuminances I _R , I _G , and I _B are constant for each color, the input terminals of the drive circuit of the IC chip 4 are in order from the one having the lowest sensitivity α _R , α _G , α _B. It also means placing them close together.

Since the photoelectric conversion element 3 formed of an organic material generally has poor sensitivity to R light, the maximum illuminances I _R , I _G , I _B and the sensitivities α _R , α _G , α _{B of} each color are known. Even if not, it is desirable to arrange the photoelectric conversion elements 3 (R1, R2, R3,...) That photoelectrically convert R light in the vicinity of the IC chip 4 as shown in FIG.

  Next, the configuration of the photoelectric conversion element will be described.

  In FIG. 3, 6 is a color filter of the photoelectric conversion element 3 formed on the glass substrate 2, 7 is an ITO anode as a first electrode of the photoelectric conversion element 3, 8 is an electron donating layer made of an electron donating material, and An organic photoelectric conversion layer 9 of the photoelectric conversion element 3 formed with an electron-accepting layer made of an electron-accepting material, and 9 is an aluminum cathode as a second electrode of the photoelectric conversion element 3.

  A method for manufacturing the image sensor configured as described above will be described.

  First, a pigment resist in which a pigment is dispersed is first applied on the glass substrate 2, prebaked, then exposed through a photomask, and then developed with an alkali developer to obtain a colored pattern. This process is repeated three times to form color filters 6 corresponding to the three primary colors R (red), G (green), and B (blue) for each column.

  Next, an ITO film having a thickness of 150 nm is formed on the glass substrate 2 by a sputtering method, and a resist material (manufactured by Tokyo Ohka Kogyo Co., Ltd., OFPR-800) is applied on the ITO film by a spin coating method to a thickness of 5 μm. The resist film is formed. Then, masking, exposure, and development are performed to pattern the resist into the shape of the ITO anode 7 and its wiring 5.

  Thereafter, the glass substrate 2 is immersed in an aqueous hydrochloric acid solution at 60 ° C. and 18 N, and the ITO film where the resist film is not formed is etched and washed with water. Finally, the resist film is removed to obtain a predetermined pattern shape. An ITO anode 7 and a wiring 5 made of an ITO film are formed.

  Next, this glass substrate 2 is subjected to ultrasonic cleaning for 5 minutes with a detergent (Semico Clean, manufactured by Furuuchi Chemical Co., Ltd.), ultrasonic cleaning for 10 minutes with pure water, and aqueous hydrogen peroxide against ammonia water (volume ratio). After washing in the order of ultrasonic cleaning for 5 minutes with a solution in which water is mixed 1: 5 and ultrasonic cleaning for 5 minutes with pure water at 70 ° C., moisture attached to the glass substrate 2 is removed with a nitrogen blower, Furthermore, it heats at 250 degreeC and makes it dry.

  Subsequently, poly (3,4) ethylenedioxythiophene / polystyrene sulphonate (PEDT / PSS) is dropped on the glass substrate 2 on which the ITO anode 7 is formed through a 0.45 μm filter, and spin coating is performed. Was applied uniformly. This is heated in a clean oven at 200 ° C. for 10 minutes to form a charge transport layer (not shown) having a thickness of 60 nm.

  Then, poly (2-methoxy-5- (2′-ethylhexyloxy) -1,4-phenylenevinylene) (MEH-PPV) functioning as an electron-donating organic material and electron-accepting material [5, 6 After spin-coating a chlorobenzene solution having a weight ratio of 1: 4 with -phenyl C61 butyric acid methyl ester ([5,6] -PCBM), it was heat-treated in a clean oven at 100 ° C. for 30 minutes, and about 100 nm The organic photoelectric conversion layer 8 is formed. Here, the organic photoelectric conversion layer 8 may be produced by any method as long as it can stably form a uniform and highly smooth thin film, such as a vacuum deposition method and a sputtering method. A vacuum process, a wet process such as a spin coating, a dipping method, or an ink jet method is preferably used. It is possible to select any process according to the material, configuration, etc. used. However, when the organic photoelectric conversion layer 8 is formed by a wet process that does not require a large-scale manufacturing apparatus, mass productivity and low cost can be achieved. Excellent and preferred.

Finally, LiF is about 1 nm and then aluminum is about 10 nm in a resistance heating vapor deposition apparatus reduced to a vacuum of 0.27 mPa (= 2 × 10 ⁻⁶ Torr) or less on the organic photoelectric conversion layer 8. The aluminum cathode 9 is formed by forming a film with a thickness of 5 nm. In this way, the photoelectric conversion elements 3 corresponding to the R, G, and B colors can be formed for each column.

  Note that MEH-PPV is a P-type organic semiconductor, [5, 6] -PCBM is an n-type organic semiconductor, and exciton electrons generated by light absorption diffuse in a conduction band [5, 6]- Holes are diffused into the PCBM and diffused into the valence band and supplied to the MEH-PPV, which is conducted to the aluminum cathode 9 and the ITO anode 7.

  This [5,6] -PCBM is a modified fullerene, has a very high electron mobility, and in addition, a mixture with MEH-PPV, which is an electron donating material, can be used. There is an advantage that the transfer can be efficiently performed, the photoelectric efficiency is increased, and the low-cost production is possible.

  The operation of the image sensor configured as described above will be described.

  FIG. 4 is a circuit diagram showing a configuration of one pixel of the image sensor in the first embodiment.

  In FIG. 4, in the photoelectric conversion element 3 formed of an organic material, incident light is photoelectrically converted into signal charges and accumulated, and the potential Vs due to the accumulated signal charges is applied to the gate of the amplifying transistor M <b> 2 via the wiring 5. Applied.

  Here, the amount of change in the potential Vs due to the signal charge that is actually photoelectrically converted and accumulated is not only the capacitance of the photoelectric conversion element 3 itself, but also the ESD element provided in the wiring capacitor 10 associated with the wiring 5 and the input terminal of the drive circuit (see FIG. (Not shown) A capacitance, an input capacitance of the amplifying transistor M2, and the like are added, and the amount of change is relatively smaller than that of the photoelectric conversion element 3 alone. In particular, when the resolution is 600 DPI or more, the capacitance of the photoelectric conversion element 3 itself becomes 1 PF (picofarad) or less, and is in the same order as the wiring capacitance 10 or the like. Therefore, the influence of these capacitances cannot be ignored.

  Since the photoelectric conversion element 3 having a small product of the maximum illuminance I and the sensitivity α originally has a small amount of change in the potential Vs due to the signal charge, it is disposed near the input terminal of the driving circuit of the IC chip 4 and is associated with the wiring 5. The influence of the wiring capacitance 10 must be suppressed. Such an arrangement is advantageous for high-speed operation because the amount of change due to signal charge can be secured even if the accumulation time is short.

  As for signal readout, the current is read out through the switching transistor M3. The sensor potential Vs is reset to the reset voltage Vr by the reset transistor M1, and the sensor accumulation time is determined by this reset operation. The timing of these operations is controlled by a shift register (not shown) or the like.

  This circuit is formed on single crystal silicon to produce a chip, and further, a gold bump is attached to the bare chip IC, and it is possible to connect to the photoelectric conversion element 3 by a mounting method that directly joins the glass substrate 2 without wire connection. it can.

  In this way, since it is arranged near the drive circuit in ascending order of the change amount of the potential Vs due to the accumulated signal charge, it is possible to suppress the decrease in the change amount of the photoelectric conversion element 3 having the small change amount. As a whole, detection is possible with a high S / N ratio.

  In the present embodiment, the case where the present invention is applied to a linear sensor has been described. However, the image sensor of the present invention is not limited to that applied to a linear sensor, and can be similarly applied to an area sensor. In this case, the signal may be read out as an XY address type using two switching transistors.

  Further, any substrate can be used as long as it can support the first electrode, the organic photoelectric conversion layer and the second electrode. Glass, polyethylene terephthalate, polycarbonate, polymethyl methacrylate, polyether sulfone, polyfluoride Various polymer materials such as vinyl, polypropylene, polyethylene, polyacrylate, amorphous polyolefin, and fluorine resin, and various metal materials such as silicon wafers are used.

  Examples of the electron donating material for forming the organic compound layer include phenylene vinylene and derivatives thereof, fluorene and derivatives thereof, particularly fluorene copolymers having a quinoline group or a pyridine group in the skeleton (P0F66, P1F66, PFPV), and fluorene-containing aryl. Polymer having repeating unit of amine polymer, carbazole and derivatives thereof, indole and derivatives thereof, pyrene and derivatives thereof, pyrrole and derivatives thereof, picoline and derivatives thereof, thiophene and derivatives thereof, acetylene and derivatives thereof, diacetylene and derivatives thereof And a group of polymer materials generically referred to as dendrimers.

  Besides polymers, for example, porphyrin compounds such as porphine, tetraphenylporphine copper, phthalocyanine, copper phthalocyanine, titanium phthalocyanine oxide, 1,1-bis {4- (di-P-tolylamino) phenyl} cyclohexane, 4 , 4 ′, 4 ″ -trimethyltriphenylamine, N, N, N ′, N′-tetrakis (P-tolyl) -P-phenylenediamine, 1- (N, N-di-P-tolylamino) naphthalene, 4,4′-bis (dimethylamino) -2-2′-dimethyltriphenylmethane, N, N, N ′, N′-tetraphenyl-4,4′-diaminobiphenyl, N, N′-diphenyl-N Aromatic tertiary amines such as N′-di-m-tolyl-4, 4′-diaminobiphenyl, N-phenylcarbazole, Stilbene compounds such as -P-tolylaminostilbene, 4- (di-P-tolylamino) -4 '-[4- (di-P-tolylamino) styryl] stilbene, triazole and derivatives thereof, oxazazole and derivatives thereof, imidazole And derivatives thereof, polyarylalkanes and derivatives thereof, pyrazolines and derivatives thereof, pyrazolone and derivatives thereof, phenylenediamine and derivatives thereof, annealed amines and derivatives thereof, amino-substituted chalcones and derivatives thereof, oxazoles and derivatives thereof, styrylanthracene and derivatives thereof , Fluorenone and its derivatives, hydrazone and its derivatives, silazane and its derivatives, polysilane aniline copolymer, polymer oligomer, styrylamine compound, aromatic Mechiridin compounds, poly 3-methylthiophene and the like can also be used.

  Examples of the electron-accepting material include 1,3-bis (4-tert-butylphenyl-1,3,4-oxadiazolyl) phenylene (OXD-7) and other oxadiazoles and derivatives thereof, anthraquinodimethane and derivatives thereof, Diphenylquinone and derivatives thereof, fullerene and derivatives thereof, particularly PCBM ([6,6] -phenyl C61 butyric acid methyl ester) carbon nanotubes and derivatives thereof are used.

ITO, ATO (Sb-doped SnO ₂ ), AZO (Al-doped ZnO) or the like is used for the transparent electrode used as the first electrode (anode) provided under the organic photoelectric conversion layer 8. Furthermore, it is possible to impart light transparency by forming the material with a light transmissive material such as a metal thin film of Al, Ag, Au or the like, thereby providing a light transmissive light receiving part.

  Examples of the second electrode (cathode) provided on the organic photoelectric conversion layer 8 include metals such as Al, Ag, Au, Cr, Cu, In, Mg, Ni, Si, and Ti, Mg—Ag alloys, and Mg—In. A thin film such as an Mg alloy such as an alloy or an Al alloy such as an Al—Li alloy, an Al—Sr alloy, or an Al—Ba alloy is used. In order to improve the short-circuit current, a method of introducing a thin film such as a metal oxide or metal fluoride between the organic photoelectric conversion layer 8 and the second electrode is also preferably used. Furthermore, ITO, ATO, AZO, etc. can be used.

  Moreover, the element structure introduce | transduced as polymeric material buffer layers, such as PEDOT: PSS (mixture of polythiophene and polystyrene sulfonic acid), between the 1st electrode or the 2nd electrode, and the organic photoelectric converting layer 8 as needed, or silicon An element structure in which an inorganic substance such as titania, alumina, carbon, zirconia or the like is introduced as a leakage current blocking layer is also preferably used.

  Furthermore, an element configuration in which a metal fluoride such as LiF, an oxide, or the like is introduced as a buffer layer between the organic photoelectric conversion layer 8 and the second electrode formed thereon as needed is also suitably used. It is done.

  In this embodiment, an example in which the color filter 6 is used as a means for separating each of the R, G, and B colors has been described. However, the spectral characteristics of the organic material may be used without using the color filter 6. Absent.

  As described above, the image sensor according to Embodiment 1 of the present invention has the following operation.

  (1) In the photoelectric conversion element 3 for each color of R, G, and B, the smaller the product of the incident maximum illuminance I (lux) and the sensitivity α [volt / (lux · time)], Therefore, the influence of the capacitance of the wiring 5 on the photoelectric conversion element 3 having a poor sensitivity characteristic can be reduced, and the signal charge from the photoelectric conversion element 3 of each color can be reduced to a high SN. The ratio can be detected reliably.

  (2) In the photoelectric conversion element 3 of each color of R, G, and B, the smaller the product of the incident maximum illuminance I (lux) and the sensitivity α [volt / (lux · time)], By arranging so that the wiring distance of each color is shortened, it is possible to absorb variations in sensitivity characteristics between the photoelectric conversion elements 3 of the respective colors due to the difference of the wiring distance, and the signal charges from the photoelectric conversion elements 3 of the respective colors can be absorbed in a short time. Can be detected.

  (3) Since the silicon transistor is formed of single crystal silicon, high mobility is possible and high-speed operation is possible, variation in threshold value can be reduced, and uniformity of sensitivity characteristics is excellent.

(Embodiment 2)
FIG. 5 is a plan view showing the arrangement of photoelectric conversion elements and drive circuits of the image sensor according to Embodiment 2 of the present invention.

  The image sensor 1a in the second embodiment is different from that in the first embodiment in that drive circuits 4a and 4b are formed of polycrystalline silicon or amorphous silicon on the glass substrate 2 at once.

  As in the first embodiment, since it is not necessary to bare-mount the IC chip 4 on which the drive circuit formed of single crystal silicon is mounted, the highly reliable image sensor 1a can be produced at a lower cost.

  In addition, since the drive circuits 4a and 4b can be arranged on both sides of the photoelectric conversion element 3 so as to sandwich the photoelectric conversion element 3, the photoelectric conversion element 3 corresponding to the color having the smallest product of the maximum illuminance I and the sensitivity α can be placed either above or below. The photoelectric conversion elements 3 corresponding to the color having the largest product of the maximum illuminance I and the sensitivity α may be arranged in the center row.

  As described above, the image sensor according to the second embodiment of the present invention has the following operation in addition to the first embodiment.

  (1) By forming the silicon transistor from polycrystalline silicon or amorphous silicon, it is not necessary to mount the chip, and it is inexpensive and excellent in mass productivity.

  (2) When the drive circuits 4a and 4b are arranged on both sides of the photoelectric conversion element 3 so as to sandwich the photoelectric conversion element 3, the wiring 5 can be drawn up and down, so that the wiring distance can be shortened and the wiring capacitance 10 can be reduced, and the high SN The signal charge can be detected by the ratio, and the accumulation time can be shortened.

  According to the present invention, the reliability of reading information with a high S / N ratio can be obtained by arranging the photoelectric conversion element in consideration of the influence of the variation in sensitivity characteristics with respect to the drive circuit formed of the silicon transistor. An excellent image sensor can be provided, and can be used for a scanner, a fax machine, and the like that extract various information such as the shape and image of an object as an electrical signal.

The top view which shows the image sensor in Embodiment 1 of this invention The top view which shows arrangement | positioning of the photoelectric conversion element and drive circuit of the image sensor in Embodiment 1 of this invention Sectional drawing which shows the structure of the photoelectric conversion element of the image sensor in Embodiment 1 of this invention. FIG. 3 is a circuit diagram illustrating a configuration of one pixel of the image sensor in the first embodiment. The top view which shows arrangement | positioning of the photoelectric conversion element and drive circuit of the image sensor in Embodiment 2 of this invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,1a Image sensor 2 Glass substrate 3 Photoelectric conversion element 4 IC chip 4a, 4b Drive circuit 5 Wiring 6 Color filter 7 ITO anode 8 Organic photoelectric conversion layer 9 Aluminum cathode 10 Wiring capacity

Claims (3)

A photoelectric conversion element in which a photoelectric conversion layer formed of an organic compound layer is sandwiched between an anode and a cathode, and a detection means for detecting an output due to a signal charge formed of at least a silicon transistor and accumulated in the photoelectric conversion element And a drive circuit having a readout means for reading out the signal charge, wherein the maximum illuminance incident on the photoelectric conversion element of each color of R, G, B is I (lux), R , G and B, when the sensitivity of the photoelectric conversion elements of each color is α [volt / (lux · time)], among the photoelectric conversion elements of each color, the product of I and α is ascending from the smallest. An image sensor, wherein the image sensor is disposed at a position close to the drive circuit. A photoelectric conversion element in which a photoelectric conversion layer formed of an organic compound layer is sandwiched between an anode and a cathode, and a detection means for detecting an output due to a signal charge formed of at least a silicon transistor and accumulated in the photoelectric conversion element And a reading circuit for reading out the signal charge, and among the photoelectric conversion elements of each color of R, G, B, the photoelectric conversion element for R light is An image sensor, wherein the image sensor is disposed at a position closest to a drive circuit. The image sensor according to claim 1, wherein the silicon transistor is formed of any one of single crystal silicon, polycrystalline silicon, and amorphous silicon.

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