Light detection device

Abstract

To reduce the size and manufacturing cost of a photodetector.SOLUTION: In order to reduce an area where a visible light sensor and an infrared light sensor are provided, a first photodiode which detects visible light and a second photodiode which detects infrared light are provided so as to overlap with each other and the first photodiode absorbs visible light first, whereby the amount of visible light incident on the second photodiode is extremely reduced. In addition, the first photodiode arranged to overlap the second photodiode is used as an optical filter of the second photodiode. Therefore, a semiconductor layer included in the first photodiode is a semiconductor layer which absorbs visible light and transmits infrared light, and a semiconductor layer included in the second photodiode is a semiconductor layer which absorbs infrared light.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a light detection device, a display device including the light detection device, and a display device including the light detection device. Regarding electronic devices. [Background technology]

[0002] In recent years, devices equipped with circuits for detecting light (also called "photodetection devices") have been used as pixel circuits for display devices. For example, Patent Document 1 discloses a touch panel that is formed integrally with a display panel. The optical sensor element (hereinafter referred to as the visible light sensor) detects the intensity of visible light, and the optical sensor element (hereinafter referred to as the infrared light sensor) detects the intensity of infrared light. The document discloses a liquid crystal display device in which optical sensor elements (hereinafter referred to as infrared optical sensors) are arranged side by side.

[0003] In the configuration of Patent Document 1, a visible light sensor and an infrared light sensor are arranged side by side, thereby achieving high accuracy. This configuration realizes touch panel functionality, and depending on the environment in which the LCD device is placed, Therefore, even if the detection accuracy of the visible light sensor is reduced due to external light and other light becoming noise, the visible light sensor The sensor detects infrared light that is not affected by visible light using an infrared sensor with different light receiving sensitivity. This enables accurate position detection even under a wide range of ambient lighting conditions. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2010 / 084640 Brochure Summary of the Invention [Problem to be solved by the invention]

[0005] As shown in Patent Document 1, a visible light sensor and an infrared light sensor are arranged side by side within a display panel. In this case, the area for arranging each sensor relative to the display becomes larger, and the pixel size becomes larger. Furthermore, as shown in Patent Document 1, when an infrared light sensor is used, the visible light to the infrared light sensor An optical filter is required to reduce noise caused by the incident light, which increases manufacturing costs. This can also be a contributing factor.

[0006] One aspect of the present invention is a light detection device configured by arranging a visible light sensor and an infrared light sensor side by side. In this case, the area occupied by each sensor is reduced by sharing the area when placing each sensor. An object of the present invention is to provide a photodetector device capable of reducing the pixel size. Another aspect of the present invention is an optical filter for reducing the incidence of visible light when an infrared light sensor is used. One object is to reduce manufacturing costs by not providing a filter. [Means for solving the problem]

[0007] One aspect of the present invention is to reduce the area required for arranging the visible light sensor and the infrared light sensor. a first photodiode that detects visible light and a second photodiode that detects infrared light; By arranging the two photodiodes in a superimposed manner, the visible light is absorbed first by the first photodiode. This significantly reduces the amount of visible light incident on the second photodiode. In one aspect, the first photodiode is arranged to overlap the second photodiode. It is used as an optical filter for the first photodiode. The semiconductor layer constituting the electrode is a semiconductor layer that absorbs visible light and transmits infrared light, and the second The semiconductor layer of the photodiode is a semiconductor layer that absorbs infrared light.

[0008] One aspect of the present invention is a photodiode for detecting visible light, a first photodiode for detecting infrared light, and a second photodiode for detecting infrared light. The second photodiode detects the accumulated photocurrent in response to the photocurrent in the first photodiode. a first amplifier circuit for amplifying and outputting the charge, and a photocurrent at a second photodiode; A second amplifier circuit is provided for amplifying and outputting the accumulated charge in response to the first flash. The semiconductor layer of the first photodiode is made of amorphous silicon, and the semiconductor layer of the second photodiode is made of amorphous silicon. The body layer is made of crystalline silicon and includes a first photodiode, a second photodiode, and a However, the first photodiode is located on the side where the incident light including visible light and infrared light is incident. The first photodiode absorbs visible light from the incident light. The second photodiode is a photodiode that detects the incident light and transmits infrared light. It is a photodetector that absorbs transmitted infrared light.

[0009] In one embodiment of the present invention, the semiconductor layer of the second photodiode is The photodetector is a semiconductor layer provided in the same layer as the semiconductor layer of the transistor of the amplifier circuit of 2. It may also be an output device.

[0010] In one embodiment of the present invention, the semiconductor layer of the first photodiode comprises a p-type semiconductor region, an i-type and an n-type semiconductor region, and The photodetector may have a first photodiode formed by stacking regions.

[0011] In one embodiment of the present invention, the second photodiode has a p-type semiconductor region, an i-type semiconductor region, and a first photodiode having an n-type semiconductor region and overlapping the second photodiode. The area where the i-type semiconductor region of the second photodiode is provided is Larger photodetectors are also possible.

[0012] In one embodiment of the present invention, the first amplifier circuit and the second amplifier circuit each include a first transformer. a first transistor, a second transistor, and a third transistor, The second and third transistors are electrically connected in series between the power supply line and the output signal line, The gate of the first transistor is electrically connected to the first terminal of the first transistor. The second terminal of the photodiode is electrically connected to one electrode of the photodetector. Good too. [Effects of the Invention]

[0013] According to one aspect of the present invention, a light detection device is provided in which a visible light sensor and an infrared light sensor are arranged side by side. In the device, the area occupied by each sensor is shared, reducing the pixel area. It is possible to provide a photodetector device that can be reduced in size. The area can also be increased, improving the sensitivity of each sensor to visible and infrared light. In addition, one embodiment of the present invention is a method for detecting incident visible light when an infrared light sensor is used. This allows for the reduction of optical filters, thereby reducing manufacturing costs. do. [Brief explanation of the drawings]

[0014] [Figure 1] 1A and 1B are a circuit diagram and a top view of one embodiment of the present invention. [Figure 2] FIG. 1 is a cross-sectional view of one embodiment of the present invention. [Figure 3] FIG. 1 is a cross-sectional view of one embodiment of the present invention. [Figure 4]1A and 1B are a circuit diagram and a timing chart according to one embodiment of the present invention. [Figure 5] FIG. 1 is a circuit diagram according to one embodiment of the present invention. [Figure 6] 10A to 10C are diagrams illustrating electronic devices according to Embodiment 3. DETAILED DESCRIPTION OF THE INVENTION

[0015] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. It is to be understood that the invention may be practiced in various different ways without departing from the spirit and scope thereof. It will be readily understood by those skilled in the art that various changes can be made in form and detail. The present invention should not be construed as being limited to the description of the present embodiment. In the configuration of the present invention, the reference numerals indicating the same objects are common among different drawings.

[0016] The size, layer thickness, and signal waveform of each component shown in the drawings of each embodiment may differ. may be exaggerated for clarity and do not necessarily represent the actual scale. Not limited to.

[0017] The terms "first," "second," "third," and "Nth" (N is a natural number) used in this specification refer to the configurations. It is added to avoid confusion of elements and is not intended to limit the number. do.

[0018] (Embodiment 1) In this embodiment, a configuration and an operation of a photodetector will be described with reference to FIGS. 1 to 4. do.

[0019] The configuration of the photodetector will be described with reference to FIG. 1. The photodetector 101 includes a first photodetector. a first photodiode 102A, a second photodiode 102B, a first amplifier circuit 103A, and It has a second amplifier circuit 103B.

[0020] The first photodiode 102A detects visible light and infrared light incident from the outside. It is a semiconductor element for detecting light. Specifically, the semiconductor of the first photodiode 102A The body layer is made up of a p-type semiconductor region, an i-type semiconductor region, and an n-type semiconductor region having amorphous silicon. The semiconductor layer of the first photodiode 102A is an i-type semiconductor region. Alternatively, the insulating film 11 may be formed by laminating a p-type semiconductor region and an n-type semiconductor region without providing the insulating film 11 . Amorphous silicon absorbs visible light incident from the outside, and It has the property of transmitting incident infrared light.

[0021] A photodiode is a device that generates a photocurrent according to the intensity of light incident from outside. Since all that is required is a photoelectric conversion element, it is sometimes called a photoelectric conversion element.

[0022] In this specification, the i-type semiconductor region refers to a semiconductor region that is imparted with p-type or n-type. The impurity is 1×10 20 cm -3 The oxygen and nitrogen concentrations are less than 5×10 19 cm -3 It refers to a semiconductor region where the concentration is less than or equal to 100 times the photoconductivity compared to the dark conductivity. In addition, the i-type semiconductor region contains boron (B) in a range of 10 ppm to 1000 ppm. The following may also be added:

[0023] The second photodiode 102B detects infrared light out of visible light and infrared light incident from the outside. It is a semiconductor element for detecting light. Specifically, the semiconductor of the second photodiode 102B The body layer is made up of a p-type semiconductor region, an i-type semiconductor region, and an n-type semiconductor region having crystalline silicon. The semiconductor layer of the second photodiode 102B is an i-type semiconductor region. Alternatively, the insulating film 11 may be formed by laminating a p-type semiconductor region and an n-type semiconductor region without providing the insulating film 11 . Crystalline silicon has the property of absorbing infrared light and visible light more than amorphous silicon.

[0024] It is effective to configure the second photodiode 102B as a lateral junction photodiode. With this configuration, the second photodiode 102B and the second transistor A first transistor 105A, a second transistor 105B, a third transistor 106A, and a third transistor Therefore, the photodetector 101 can be fabricated simultaneously with the phototransistor 106B. Specifically, the second photodiode 102B and the second transistor 1 105A, the second transistor 105B, the third transistor 106A, and the third transistor The formation of the semiconductor layer constituting the capacitor 106B, the formation of the impurity region, etc. can be performed simultaneously. Cut.

[0025] The first amplifier circuit 103A amplifies light incident on the first photodiode 102A from the outside. In particular, it amplifies the charge accumulated in response to the photocurrent generated by visible light and outputs it as an electrical signal. Specifically, the charge accumulated according to the photocurrent is input to the first amplifier circuit 103. The reset operation, storage operation, and selection operation performed by the multiple transistors of A The signal is converted into an amplified electrical signal and output to the outside.

[0026] The first amplifier circuit 103A includes a first transistor 104A (also called a transfer transistor). , the second transistor 105A (also referred to as an amplifying transistor) and the third transistor 1 06A (also called a selection transistor). The first amplifier circuit 103A is connected to a transfer control line 107 (also referred to as a first wiring) and a power supply line 108 (also referred to as a second wiring). The first output signal line 11 0A (also called the fourth wiring) and the reset control line 111 (also called the fifth wiring) It will be controlled.

[0027] One electrode of the first photodiode 102A is connected to a reset control line 111. The other electrode of the first photodiode 102A is connected to the first terminal of the first transistor 104A. The gate of the first transistor 104A is connected to the transfer control line 107. The second terminal of the first transistor 104A is connected to the gate of the second transistor 105A. The first terminal of the second transistor 105A is connected to the power supply line 108. The second terminal of the second transistor 105A is connected to the first terminal of the third transistor 106A. The gate of the third transistor 106A is connected to the selection control line 109. The second terminal of the transistor 106A is connected to the first output signal line 110A.

[0028] In this specification, "A and B are connected" does not mean that A and B are directly connected. In addition to those that are electrically connected, A and B are also included. Being connected to means that there is an object that has some electrical effect between A and B. This represents the case where the part between A and B that includes the object becomes a node.

[0029] Specifically, A and B are connected via a switching element such as a transistor. When the switching element is turned on, A and B may be at approximately the same potential, or when the resistance element is turned on, A and B are connected via a resistor, and the potential difference generated across the resistor is When considering circuit operation, for example, if the voltage between A and B is low enough that it does not affect the operation of This indicates that it is acceptable to regard the parts as the same node.

[0030] A transistor has at least three terminals including a gate, a drain, and a source. The element has a channel region between a drain region and a source region, and the drain A current can flow through the source region, the channel region, and the source region. The source and drain are different depending on the transistor structure and operating conditions. Therefore, in this specification, it is difficult to define whether the source is a drain or a source. The regions that function as a source and a drain may not be called a source or a drain. In that case, for example, they may be referred to as the first terminal and the second terminal, respectively. These may be referred to as the first electrode and the second electrode, respectively. It may also be referred to as a drain region.

[0031] The first transistor 104A is connected to the first photodiode 104B by a signal on the transfer control line 107. The charge accumulated by the photocurrent generated by the incident visible light on the diode 102A is transferred to the second This is a transistor for transferring the voltage to the gate of the transistor 105A. The first photodiode 102A is illuminated with visible light, and the second photodiode 105A is generated by the visible light incident on the first photodiode 102A. The gate potential corresponds to the charge accumulated by the photocurrent generated by the photocurrent. The third transistor amplifies the current flowing between the first terminal and the second terminal. 106A is connected to the source and drain of the second transistor 105A by a signal on the selection control line 109. The current flowing between the power supply line 108 and the first output signal line 110A flows between the power supply line 108 and the first output signal line 110A. This is a transistor for controlling this.

[0032] The second amplifier circuit 103B, like the first amplifier circuit 103A, includes a second photodiode The electric current accumulated in response to the photocurrent generated by the light, especially infrared light, incident on 102B from the outside. It is a circuit that amplifies the charge and outputs it as an electrical signal. The charges are stored in the plurality of capacitors of the second amplifier circuit 103B, similarly to the first amplifier circuit 103A. The reset, storage, and selection operations performed by the transistors produce an amplified electrical signal. The signal is converted into a signal and output to the outside.

[0033] The second amplifier circuit 103B includes a first transistor 104B (also called a transfer transistor). , the second transistor 105B (also referred to as an amplifying transistor) and the third transistor 1 06B (also called a selection transistor). The second amplifier circuit 103B is connected to a transfer control line 107, a power supply line 108, a selection control line 109, and a second The output signal line 110B (also referred to as the sixth wiring) and the reset control line 111 This will be the case.

[0034] The transfer control line 107, the power supply line 108, and the selection control line 109 are connected to the second amplifier circuit 103B. The reset control line 109 and the reset control line 111 are different from the wirings connected to the first amplifier circuit 103A. The wiring connected to the second amplifier circuit 103B may be the wiring connected to the first amplifier circuit 103B. By using wirings different from the wirings connected to the first amplifier circuit 103A, The control of the amplifier circuit 103B can be performed at a different timing.

[0035] One electrode of the second photodiode 102B is connected to a reset control line 111. The other electrode of the second photodiode 102B is connected to the first terminal of the first transistor 104B. The gate of the first transistor 104B is connected to the transfer control line 107. The second terminal of the first transistor 104B is connected to the gate of the second transistor 105B. The first terminal of the second transistor 105B is connected to the power supply line 108. The second terminal of the second transistor 105B is connected to the first terminal of the third transistor 106B. The gate of the third transistor 106B is connected to the selection control line 109. The second terminal of the transistor 106B is connected to a second output signal line 110B.

[0036] The first transistor 104B is connected to the second photodiode 104B by a signal on the transfer control line 107. The charge accumulated by the photocurrent generated by the incident infrared light on the second electrode 102B is transferred to the second electrode 102B. This is a transistor for transferring the voltage to the gate of the transistor 105B. The second photodiode 102B is illuminated with infrared light, and the second photodiode 105B is generated by the infrared light. The gate potential corresponds to the charge accumulated by the photocurrent generated by the photocurrent. The third transistor amplifies the current flowing between the first terminal and the second terminal. 106B is connected to the source and drain of the second transistor 105B by a signal on the selection control line 109. The current flowing between the power supply line 108 and the second output signal line 110B flows between the power supply line 108 and the second output signal line 110B. This is a transistor for controlling this.

[0037] FIG. 1B shows a top view of the photodetector 101 shown in FIG. 1A according to one embodiment of the present invention. In FIG. 1B, similarly to FIG. 1A, a first photodiode 102A, a second photodiode 102B, and a a photodiode 102B, a first transistor 104A constituting a first amplifier circuit, a second The first transistor 105A and the third transistor 106A constitute a second amplifier circuit. The first transistor 104B, the second transistor 105B, and the third transistor 1B also shows the transfer control line 107, Power supply line 108, selection control line 109, first output signal line 110A, second output signal line 110 B, Reset control line 111 is shown.

[0038] In addition, the top view shown in FIG. 1(B) illustrates the arrangement of each element formed by wiring and semiconductor layers. For clarity, the insulating layers are not shown, but insulating layers or the like are provided between the conductive layers as appropriate. Connections between the wires are made through openings in the insulating layer.

[0039] The first photodiode 102A of this embodiment shown in FIG. 1B is a second photodiode. Specifically, the first photodiode 102A is provided so as to overlap with the first photodiode 102B. The second photodiode 102B includes a p-type semiconductor region, an i-type semiconductor region, and an n-type semiconductor region. It is preferably provided on the conductor region. The photodiode 102A has at least the i-type semiconductor region of the second photodiode 102B. The structure is such that the sensor is provided on an area that will become a target area.

[0040] By using the configuration of FIG. 1B, the first photodiode 102, which is a visible light sensor, A second photodiode 102B, which is an infrared light sensor, is arranged in parallel. In the detection device, the area occupied by each sensor is shared to reduce the area required. As a result, the area required for arranging each sensor can be reduced, resulting in a smaller pixel size. Therefore, it is possible to provide a photodetector device that can reduce the size of each sensor. The area of ​​the sensor can be increased, improving the sensitivity of each sensor to visible and infrared light. It can be raised.

[0041] The semiconductor layer of the first photodiode 102A, which is a visible light sensor, is amorphous silicon. The lens has the property of absorbing visible light incident from the outside and transmitting infrared light incident from the outside. As a result, by using the configuration shown in FIG. 1(B), the second photodiode, which is an infrared light sensor, Therefore, the incidence of visible light on the electrode 102B can be reduced. In the case of the second photodiode 102B configured to detect infrared light as the light source layer, An optical filter that reduces noise during detection is separately provided on the second photodiode 102B. Since there is no need to use a soldering iron, the manufacturing cost can be reduced.

[0042] Next, in FIG. 2(A), the dashed lines A1-A2 and A3-A4 in the top view shown in FIG. 1(B) are shown. 2(B) is a cross-sectional view corresponding to the dashed line B1-B2 in the top view shown in FIG. 1(B). Shows.

[0043] 2(A) will be described. In the cross-sectional view shown in FIG. 2(A), A light-shielding layer 201 and an undercoat film 202 are provided. The p-type semiconductor region 203 and the i-type semiconductor region 204 in the second photodiode 102B are The p-type semiconductor region 203 and 204 in the second photodiode 102B are provided. The second transistor 105B is formed in the same layer as the semiconductor layer that forms the i-type semiconductor region 204. The semiconductor layer is provided with an n-type semiconductor region 205 and an i-type semiconductor region 206. Similarly, the p-type semiconductor region 203 and the i-type semiconductor region The semiconductor layer of the third transistor 106B is formed in the same layer as the semiconductor layer forming the 204. An n-type semiconductor region 207 and an i-type semiconductor region 208 are provided. The p-type semiconductor region 203 and the i-type semiconductor region 204 in the diode 102B are formed In the same layer as the semiconductor layer, an n-type semiconductor region constituting the semiconductor layer of the first transistor 104A is provided. An area 209 is provided.

[0044] The transparent substrate 200 is a substrate made of a material that is transparent to visible light and infrared light. For example, a plastic substrate that is transparent to visible light and infrared light, a visible A glass substrate that is translucent to light and infrared light can be used.

[0045] The light-shielding layer 201 prevents infrared light and visible light from the backlight from reaching the first photodiode 1. This is to prevent the light from being incident on the first photodiode 102A and the second photodiode 102B. The light-shielding layer 201 is made of a metal material such as aluminum or chromium that can block infrared light and visible light. is formed by sputtering, CVD or coating using The light-shielding layer 201 is formed by processing using a lithography method and an etching method. Not only the region stacked with the photodiode 102B, but also the first amplifier circuit 103A and the second It may also be provided in an area laminated with the semiconductor layers of the transistors that make up the amplifier circuit 103B. The light-shielding film shields the semiconductor layer of each transistor from light, preventing light from entering the backlight. The incidence of infrared and visible light from these sources causes deterioration of characteristics such as a shift in the threshold voltage of transistors. The backlight is configured as a transparent Any configuration may be used as long as a light source capable of emitting infrared light and visible light from the substrate 200 side is used. Specifically, the backlight is configured with a light emitting diode that emits infrared light and a light emitting diode that emits visible light. The light emitting diodes may be arranged side by side.

[0046] Here, the backlight is a first photodiode that detects visible light and infrared light. The light is incident on the light-transmitting substrate 200 so as to be incident on the first photodiode 102A and the second photodiode 102B. The infrared light may be emitted separately from the opposing substrate side.

[0047] The base film 202 is made of alkali metals such as Na and alkaline earth metals contained in the light-transmitting substrate 200. This prevents metalloids from diffusing into the second photodiode 102B and adversely affecting its characteristics. The base film 202 is formed by depositing silicon oxide, silicon nitride, or the like using a CVD method, a sputtering method, or the like. A single layer or laminate of a material having light transmitting and insulating properties, such as silicon oxynitride or silicon nitride oxide, is used. The surface of the base film 202 is the semiconductor of the second photodiode 102B. When forming the layers, it is preferable to form them so as to improve flatness.

[0048] The semiconductor layer of the second photodiode 102B is made of crystalline silicon such as polycrystalline silicon. A second photodiode made of a semiconductor layer having crystalline silicon can be used. The electrode 102B includes a p-type semiconductor region 203, an i-type semiconductor region 204, and an n-type semiconductor region ( (not shown) are provided horizontally on the light-transmitting substrate 200. The semiconductor layers of the transistors constituting the second amplifier circuit 103B are also made of a crystalline silicon or the like. The n-type semiconductor region 207, the i-type semiconductor region 208, and the n-type semiconductor region 209 are formed using crystalline silicon. 209 is provided. The semiconductor layers of the second photodiode 102B and each transistor are The deposited crystalline silicon is processed using photolithography and etching, and then After forming a mask by photolithography, p-type or n-type impurity regions are formed. The formation is performed by ion implantation or ion doping.

[0049] The semiconductor layer of the second photodiode 102B is made of single crystal silicon by the bonding and peeling method. First, a semiconductor wafer such as a silicon wafer can be formed by , hydrogen ions (H + , H2 + , H3 + etc.) or hydrogen ions and helium ions are added The semiconductor wafer is bonded onto the base film 202, forming an embrittlement layer in the semiconductor wafer. Then, the semiconductor layer is formed on the base film 202 by peeling at the embrittlement layer by heat treatment. The depth from the surface of the wafer to the embrittlement layer corresponds to the thickness of the semiconductor layer, so the addition of hydrogen ions, etc. By controlling the conditions, the thickness of the semiconductor layer can be adjusted.

[0050] In the cross-sectional view shown in FIG. 2A, the semiconductor layer of the second photodiode 102B , the semiconductor layer of the second transistor 105B, the semiconductor layer of the third transistor 106B, and An insulating layer 210 is provided on the semiconductor layer of the first transistor 104A. On the i-type semiconductor region 206 through the line 0, a transfer control line 107, a power supply line 108 and a selection control line A gate electrode 211 is provided, which is formed in the same layer as the line 109. On the semiconductor region 208, the transfer control line 107, the power supply line 108 and the selection control line 109 are formed in the same layer. On the insulating layer 210, a gate electrode 212 is formed. A power supply line 108 is provided, which is formed in the same layer as the selection control line 109 .

[0051] The insulating layer 210 is formed by adding alkali metals such as Na or alkaline earth metals from the outside to the second phase. The insulating layer 210 prevents the diffusion of the semiconductor into the photodiode 102B and adversely affecting its characteristics. Using plasma CVD or sputtering, silicon oxide film, silicon oxynitride film, Alternatively, a single layer of a material having light transmitting and insulating properties, such as a silicon nitride oxide film or an organic resin film, may be used. It is formed by laminating.

[0052] The various wirings formed in the same layer as the gate electrode 211 and the gate electrode 212 have conductivity. The conductive metal material may be molybdenum, Titanium, chromium, tantalum, tungsten, aluminum, copper, neodymium, scandium It is formed in a single layer or laminated layer using metal materials such as these or alloy materials that contain these as the main components. It is formed by sputtering or vacuum deposition.

[0053] In the cross-sectional view shown in FIG. 2(A), the insulating layer 210, the gate electrode 211, and the gate electrode 21 An insulating layer 213 is provided on the insulating layer 210 and the power line 108. A first output signal line is provided between the n-type semiconductor region 205 and the n-type semiconductor region 207 via the 110A, a conductive layer formed in the same layer as the second output signal line 110B, and the reset control line 111. 214 is provided on the n-type semiconductor region 207 via the insulating layer 210 and the insulating layer 213. The second output signal line 110B is formed in the same layer as the first output signal line 110A and the reset control line 111. The n-type semiconductor region 20 is provided with the insulating layer 210 and the insulating layer 213 interposed therebetween. 5 and the power supply line 108, a first output signal line 110A and a second output signal line 110B are provided. A conductive layer 215 is provided in the same layer as the reset control line 111. A first output signal line 110A, a second output signal line 110B, and a third output signal line 110C are provided on the p-type semiconductor region 203 via the insulating layer 213. A conductive layer 216 is provided which is formed in the same layer as the output signal line 110B and the reset control line 111. A first output is formed on the n-type semiconductor region 209 via the insulating layer 210 and the insulating layer 213. The signal line 110A, the second output signal line 110B, and the reset control line 111 are formed in the same layer. A conductive layer 217 is provided.

[0054] The insulating layer 213 is a silicon oxide film formed by using a plasma CVD method, a sputtering method, or the like. a silicon oxynitride film, a silicon nitride oxide film, an organic resin film, or the like, which has light transmitting and insulating properties; The material having the above properties is formed as a single layer or a laminate.

[0055] The conductive layers 214 to 217 are formed by a sputtering method or a vacuum evaporation method. Lithium, titanium, chromium, tantalum, tungsten, aluminum, copper, yttrium Metals such as these, alloy materials containing these as the main component, or conductive materials such as indium oxide A material such as a metal oxide is formed as a single layer or a multilayer.

[0056] In the cross-sectional view shown in FIG. 2A, the first photoresist is formed on the insulating layer 213 and the conductive layer 216. The p-type semiconductor region 218, the i-type semiconductor region 219, and the n-type semiconductor region 220 in the diode 102A. A conductor region 220 is provided. Note that the p-type semiconductor in the first photodiode 102A The region 218 is provided by being laminated with the conductive layer 216 so that the end portion thereof overlaps the conductive layer 216 .

[0057] The semiconductor layer of the first photodiode 102A may be made of amorphous silicon. The first photodiode 102A, which is made of a semiconductor layer having amorphous silicon, The p-type semiconductor region 218, the i-type semiconductor region 219, and the n-type semiconductor region 220 are formed on the light-transmitting substrate 2. 00 and are stacked vertically.

[0058] The p-type semiconductor region 218 is formed of amorphous silicon containing an impurity element that imparts p-type conductivity. The p-type semiconductor region 218 is formed by using an impurity element of Group 13 (for example, boron (B)). The semiconductor material gas is used to form the film by plasma CVD. Or, Si2H6, SiH2Cl2, SiHCl3 Alternatively, SiCl4, SiF4, etc. may be used. The thickness of the p-type semiconductor region 218 is 10 nm or more. It is preferable to form it so that the thickness is 50 nm or less.

[0059] The i-type semiconductor region 219 is formed of amorphous silicon. The semiconductor material gas is used to form amorphous silicon by the plasma CVD method. Silane (SiH4) may be used as the conductive material gas. Alternatively, Si2H6, Si H2Cl2, SiHCl3, SiCl4, SiF4, etc. may also be used. The film thickness of 19 is preferably formed to be 200 nm or more and 1000 nm or less.

[0060] The n-type semiconductor region 220 is formed of amorphous silicon containing an impurity element that imparts n-type conductivity. The n-type semiconductor region 220 is formed by doping with an impurity element of Group 15 (for example, phosphorus (P)). The semiconductor material gas is used to form the film by plasma CVD. Or, Si2H6, SiH2Cl2, SiHCl3 Alternatively, SiCl4, SiF4, etc. may be used. The thickness of the n-type semiconductor region 220 is 20 nm or more. It is preferable to form it so that the thickness is 200 nm or less.

[0061] In the cross-sectional view shown in FIG. 2A, the first photodiode 102A and the second output signal On the line 110B, the conductive layer 214, the conductive layer 215, the conductive layer 216, and the conductive layer 217, an insulating layer is formed. The n-type semiconductor region 220 and the conductive layer 217 are connected via the insulating layer 221. A conductive layer 222 formed in the same layer as the conductive layer that serves as the pixel electrode is provided between them.

[0062] The insulating layer 221 is a silicon oxide film formed by using a plasma CVD method, a sputtering method, or the like. a silicon oxynitride film, a silicon nitride oxide film, an organic resin film, or the like, which has light transmitting and insulating properties; The insulating layer 221 is formed by using a single layer or a stack of layers of a material having a flat surface. It is preferable to use an insulating layer.

[0063] The conductive layer 222 may be formed of indium tin oxide (Ind) as long as it is a conductive layer that transmits light. Indium Tin Oxide, Indium Tin Oxide with Silicon Oxide, Indium Oxide It is formed using a material such as indium zinc oxide.

[0064] Next, FIG. 2B will be described. In the cross-sectional view shown in FIG. 2B, the transparent substrate 200 A light-shielding layer 201 and an undercoat film 202 are provided on the light-shielding layer 201. On the second photodiode 102B, a p-type semiconductor region 203 and an i-type semiconductor Region 204 and n-type semiconductor region 223 are provided.

[0065] In the cross-sectional view shown in FIG. 2B, the semiconductor layer of the second photodiode 102B An insulating layer 210 is provided on the insulating layer 210. The transfer control line 107 and the selection control line 108 are provided on the insulating layer 210. A power supply line 108 is provided, which is formed in the same layer as the power supply line 109.

[0066] In the cross-sectional view shown in FIG. 2B, the insulating layer 210 and the power supply line 108 are covered with the insulating layer 21. 3 is provided on the p-type semiconductor region 203 via the insulating layer 210 and the insulating layer 213. The first output signal line 110A, the second output signal line 110B, and the reset control line 111 are arranged in the same layer. The n-type semiconductor layer 216 is formed on the insulating layer 210 and the insulating layer 213. On the body region 223, a first output signal line 110A, a second output signal line 110B, a reset A conductive layer 224 is provided, which is formed in the same layer as the control line 111 .

[0067] In the cross-sectional view shown in FIG. 2B, the first photoresist film is formed on the insulating layer 213 and the conductive layer 216. The p-type semiconductor region 218, the i-type semiconductor region 219, and the n-type semiconductor region 220 in the diode 102A. A conductor region 220 is provided. Note that the p-type semiconductor in the first photodiode 102A The region 218 is provided by being laminated with the conductive layer 216 so that the end portion thereof overlaps the conductive layer 216 .

[0068] In the cross-sectional view shown in FIG. 2B, the first photodiode 102A, the conductive layer 216, An insulating layer 221 is provided on the conductive layer 224 .

[0069] Next, in FIG. 3(A), in the cross-sectional view of the photodetector shown in FIG. 2(A) and FIG. 2(B), A first photodiode 102A and a second photodiode 102B for infrared light and visible light The arrows in Figure 3(A) show the state of the first In addition to the photodiode 102A and the second photodiode 102B, the backlight 30 3, a liquid crystal layer 301, an opposing substrate 302, and an object to be detected 303. 02 may be a substrate made of the same material as the light-transmitting substrate 200. Electrodes for the liquid crystal display, color filters, polarizing plates, and alignment films that are provided as needed. The configuration of the backlight 300 in FIG. As the light source, a light source capable of emitting infrared light and visible light separately from the light-transmitting substrate 200 side is used. The backlight 300 is configured as a light-emitting diode that emits infrared light. A light emitting diode that emits visible light and a light emitting diode that emits visible light may be arranged side by side.

[0070] In one embodiment of the present invention, as shown by the dashed arrow 304 in FIG. 3, After passing through the liquid crystal layer 301, the infrared light from the backlight passes through the counter substrate 302. The light that has passed through the counter substrate 302 is reflected by a finger, which is the object to be detected 303, and then returns to the counter substrate 302. The light incident on the counter substrate 302 is incident on the first photodiode 102A. The light passes through the photodiode 102B and enters the second photodiode 102B. The display device having the device detects the infrared light by the second photodiode 102B, Equipped with an optical touch panel function that detects objects such as fingers without being affected by external light. The configuration can be such that:

[0071] In one embodiment of the present invention, as shown by the dashed-dotted arrow 305 in FIG. Visible light from the backlight passes through the liquid crystal layer 301 and then passes through the opposing substrate 302. The light that has passed through the opposing substrate 302 is then perceived by the viewer. The light passes through the substrate 302 and the liquid crystal layer 301 and is incident on the first photodiode 102A. In addition, the display device including the photodetector according to this embodiment has a first photodiode 1 The 02A detects visible light, allowing for touch panel functionality that is not affected by external light. In addition, the image forming apparatus may be configured to have a scanner function for detecting an object to be detected, such as a color image. do.

[0072] Also, FIG. 3(B) shows a different configuration of the backlight from that shown in FIG. 3(A). The backlight shown in (B) has a light source for emitting visible light and also emits infrared light. It is equipped with a front light for illumination.

[0073] The front light shown in FIG. 3(B) includes a light source 306, a light guide plate 307, a fixing member 308, and The front light shown in FIG. 3B includes a first photodiode 102A. and the second photodiode 102B.

[0074] The light source 306 may be a light emitting diode that emits infrared light.

[0075] The fixing member 308 has a function of fixing the light source 306 and the light guide plate 307. It is preferable to use a material having a light-blocking property as the fixing material 308. By using the material, the light emitted from the light source 306 is prevented from leaking to the outside. It should be noted that the fixing material 308 does not necessarily have to be provided.

[0076] In the front light shown in FIG. 3B, light from a light source 306 is incident on a light guide plate 307. For example, when the object 303 to be detected is not in contact with the light guide plate 307, the light from the light source 306 is guided The light is totally reflected inside the plate 307. When the object 303 to be detected, such as a finger, comes into contact with the light guide plate 307, The light from the light source 306 is scattered at the contact portion between the object 303 and the light guide plate 307. The light passes through the first photodiode 102A and enters the second photodiode 102B.

[0077] By using the configurations shown in FIGS. 3(A) and 3(B), the first photodiode, which is a visible light sensor, A first photodiode 102A and a second photodiode 102B, which is an infrared light sensor, are arranged in parallel. In a photodetector configured with these sensors, the area occupied by each sensor is shared. As a result, the area required for arranging each sensor can be reduced. Therefore, it is possible to provide a photodetector device that can reduce the pixel size. The area of ​​the sensor can be increased, so the sensitivity of each sensor to visible light and infrared light can be increased. It can be improved.

[0078] The semiconductor layer of the first photodiode 102A, which is a visible light sensor, is amorphous silicon. The lens has the property of absorbing visible light incident from the outside and transmitting infrared light incident from the outside. As a result, by using the configuration shown in FIG. 3, the second photodiode, which is an infrared light sensor, Therefore, the crystalline silicon can be used as a semiconductor layer. In the case of the second photodiode 102B configured to detect infrared light as a Therefore, it is necessary to provide an optical filter on the second photodiode 102B to reduce the noise. Therefore, the manufacturing cost can be reduced.

[0079] Next, an example of a configuration having a plurality of photodetectors 101 shown in FIG. 1(A) arranged in a matrix will be described. Shown in Figure 4(A).

[0080] In FIG. 4A, a plurality of photodetectors 101 are arranged in m (m is a natural number of 2 or more) rows and n (n is a natural number of 2 or more) rows. The photodetector devices 10 shown in FIG. 1 is connected to one of a plurality of reset control lines PR (referred to as wiring PR1 to wiring PRm). , any one of a plurality of transfer control lines TX (written as wiring TX1 to wiring TXm) and a plurality of Any one of the selection control lines SE (written as lines SE1 to SEm) and a plurality of power supply lines V R (written as wiring VR1 to wiring VRm) and an example of Each row of the photodetector devices 101 shown in FIG. 4A has a plurality of first output signal lines VIOUT (Will be referred to as wiring VIOUT1 to wiring VIOUTn) and multiple second outputs Any one of the signal lines IROUT (written as lines IROUT1 to IROUTn) The example shown is connected to

[0081] In FIG. 4A, the photodetectors in each row share a transfer control line TX. A reset control line PR is shared among the photodetectors in each row, and a selection control line SE is shared among the photodetectors in each row. The photodetectors in each row share a power supply line VR, and the photodetectors in each column share a first output line VR. The photodetector devices in each column share a common output signal line VIOUT. The configuration is not limited to the above, and two or more transfer control lines TX may be provided in each row. Alternatively, two or more reset control lines P may be connected to different photodetector devices 101 in each row. Alternatively, two or more selection lines R may be provided in each row to connect to different photodetectors 101. Alternatively, a selection control line SE may be provided to connect the photodetectors 101 to different ones of the photodetectors 101. Alternatively, two or more power supply lines VR may be provided to connect different photodetectors 101. Two or more first output signal lines VIOUT and / or second output signal lines IROUT are provided in a column. Alternatively, two photodetectors 101 may be provided and connected to different photodetectors 101 .

[0082] In addition, in FIG. 4A, the wiring VR is shared by the photodetectors in each row. The wiring VR may be shared by the photodetectors in each column.

[0083] Next, the operation of the photodetector 101 will be described. Each wiring (transfer control line TX, reset control line PR, selection control line SE, first output signal line VI OUT (second output signal line IROUT)), and a second transistor 105A (second transistor The change in the potential (indicated as FD in FIG. 4(B)) corresponding to the gate potential of the transistor 105B 4B is an example of a timing chart showing the first photodiode. The operation of the second photodiode 102A and the first amplifier circuit 103A and the operation of the second photodiode 103B are Since the operation of the first amplifier circuit 102B and the second amplifier circuit 103B is the same, The operation of the photodiode 102A and the first amplifier circuit 103A will be explained. Let's say.

[0084] In the timing chart shown in FIG. 4B, the operation of the photodetector 101 is explained. Therefore, the transfer control line TX, the selection control line SE, and the reset control line PR are set to high or low. Specifically, it is assumed that a high level potential is applied to the transfer control line TX. A potential HTX of high level and a potential LTX of low level are applied to the selection control line SE. A high level potential HSE and a low level potential LSE are applied, and the reset control The wire PR is given a high level potential HPR and a low level potential LPR. do.

[0085] The first transistor 104A, the second transistor 105A, and the third transistor The following description will be given assuming that all transistors 106A are n-channel transistors. The conductivity type of the transistor may be a p-channel type transistor, in which case the signal supplied to each terminal The polarity can be reversed.

[0086] First, at time T1, the potential of the transfer control line TX is changed from the potential LTX to the potential HTX. When the potential of the transfer control line TX becomes the potential HTX, the first transistor 104A is turned on. At time T1, the selection control line SE is given a potential LSE, and the reset state is A potential LPR is applied to the bit control line PR.

[0087] At time T2, the potential of the reset control line PR is changed from the potential LPR to the potential HPR. At time T2, the potential of the transfer control line TX remains at the potential HTX. The potential of the line SE remains at the potential LSE. Thus, a resistor is applied to the gate (FD) of the second transistor 105A. Since the potential HPR of the set control line PR is applied, the gate of the second transistor 105A The charge held in (FD) is discharged.

[0088] At time T3, the potential of the reset control line PR is changed from the potential HPR to the potential LPR. Until just before time T3, the potential of the gate (FD) of the second transistor 105A is at the potential H Since the potential of the reset control line PR is kept at the potential LPR, when the potential of the reset control line PR becomes the potential LPR, A reverse bias voltage is applied to the first diode 102A. With a reverse bias voltage applied to the photodiode 102A, the first photodiode When visible light is incident on the first photodiode 102A, a reset control A current (photocurrent) flows in the direction of the line PR. The value of the photocurrent changes according to the intensity of the incident light. That is, the higher the intensity of light incident on the first photodiode 102A, the higher the photodiode The current value of the current becomes high, and the gate (FD) of the second transistor 105A and the first photodiode The amount of charge moving between the first photodiode 102A also increases. The lower the intensity of the light incident on the second transistor 102A, the lower the value of the photocurrent. The amount of charge moving between the gate (FD) of 105A and the first photodiode 102A is also Therefore, the potential of the gate (FD) of the second transistor 105A decreases as the intensity of light increases. The higher the intensity, the greater the change, and the lower the light intensity, the smaller the change.

[0089] At time T4, when the potential of the transfer control line TX is changed from the potential HTX to the potential LTX, The first transistor 104A is turned off. The charge transfer between the gate (FD) and the first photodiode 102A stops, The potential of the gate (FD) of the second transistor 105A is determined.

[0090] At time T5, the potential of the selection control line SE is changed from the potential LSE to the potential HSE. The third transistor 106A is turned on. Then, the potential of the wiring Charge transfer occurs between VR and the first output signal line VIOUT.

[0091] Before time T5, the potential of the first output signal line VIOUT is set to a predetermined potential (progression). In FIG. 4B, the first output signal line VIOU The potential of T is precharged to a low level potential before time T5, and The case where the potential of the first output signal line VIOUT rises in accordance with the light intensity during The potential of the first output signal line VIOUT is set to a high level potential before time T5. and the first output signal line VI The potential of OUT may decrease.

[0092] The precharge operation is performed by, for example, connecting the first output signal line VIOUT and a line to which a predetermined potential is applied. The line is electrically connected to the transistor through a switching element such as a transistor. After the precharge operation is completed, The transistor is in an off state.

[0093] At time T6, the potential of the selection control line SE is changed from the potential HSE to the potential LSE. The movement of charges from the wiring VR to the first output signal line VIOUT stops, and the first output signal line V The potential of the first output signal line VIOUT is determined. The potential of the output signal corresponds to the potential of the output signal of the sensor 1. The potential of the output signal contains information about the object to be detected. are.

[0094] The above series of operations of the photodetector 101 can be classified into a reset operation, a storage operation, and a selection operation. That is, the operation from time T2 to time T3 is the reset operation, and from time T3 The operation up to time T4 corresponds to the accumulation operation, and the operation from time T5 to time T6 corresponds to the selection operation. Also, the period from the end of the storage operation to the start of the selection operation, that is, time T4 The period from time T1 to time T5 is when a charge is generated at the gate (FD) of the second transistor 105A. This corresponds to the charge retention period during which the charge is retained. In each photodetector, a reset operation, a storage operation, and a selection operation are sequentially performed. A ring shutter system can be used. In each photodetector, the reset operation and the accumulation operation are performed simultaneously, and the selection operation is performed sequentially. The so-called global shutter method can be used.

[0095] Here, when the potential of the transfer control line TX is changed at time T1 or time T4, The parasitic capacitance between the control line TX and the gate (FD) of the second transistor 105A The potential of the gate (FD) of the transistor 105A in step 2 changes. This change in potential is large. In this case, the output signal cannot be output accurately. In order to suppress the change in the potential of the gate (FD) of the second transistor 105A, The capacitance between the gate and source or the gate and drain of the transistor 104A is low. It is also effective to increase the gate capacitance of the second transistor 105A. Furthermore, it is effective to electrically connect a capacitance element to the gate (FD) of the second transistor 105A. In Figure 4(B), these measures are taken to When the potential of the transmission control line TX is changed, the gate (FD) of the second transistor 105A The change in potential is assumed to be negligible.

[0096] The photodetector 101 in each row is connected to a transfer control line TX, a reset control line PR, and a selection control line. Two control lines SE are provided for each of the first and second amplifier circuits 103A and 103B. It is effective to configure the photodetector 101 so that the operation in the photodetector 101 is performed independently of the operation in the photodetector 103B. Then, one electrode of the first photodiode 102A is connected to a first reset control line, One electrode of the second photodiode 102B is connected to the second reset control line, and the first The gate of the transistor 104A is connected to the first transfer control line, and the first transistor 104 The gate of the third transistor 106A is connected to the first transfer control line. the gate of the third transistor 106B is connected to the second select control line; The first transfer control line and the second transfer control line are controlled independently, and the first reset control line and The first selection control line and the second reset control line are controlled independently, and the first selection control line and the second selection control line are controlled independently. It is effective to have a configuration in which the control is performed independently. Further enhancement of functionality is possible. The operation in the first amplifier circuit 103B and the operation in the second amplifier circuit 103B are performed independently, and in the second period, The operation in the first amplifier circuit 103A and the operation in the second amplifier circuit 103B are performed in parallel. It may be configured to perform this.

[0097] As an example of the configuration, in the photodetector 101, the first photodiode 102A By adopting such a configuration, the photodetector 101 can be configured to perform detection only by the photodetector. Specifically, the reset operation in the first amplifier circuit 103A is When the storage operation and selection operation are performed, the second amplifier circuit 103B performs a reset operation, a storage operation, and a selection operation. In the first period, at least one of the first operation and the selection operation is not performed. In the second period, only the detection by the first photodiode 102A is performed, and in the second period, the first amplification circuit The operation in the first amplifier circuit 103A and the operation in the second amplifier circuit 103B are performed in parallel. That's fine.

[0098] As another example of the above configuration, in the photodetector 101, the second amplifier circuit 103B When performing a reset operation, a storage operation, and a selection operation in the first amplifier circuit 103A, It is possible to configure the photodetector 101 so that only the accumulation operation is performed. Furthermore, the first photodiode 102A receives light in a specific wavelength range. Since it functions as a filter that absorbs light, the detection by the second photodiode 102B It is possible to improve the accuracy. In the first period, the second amplifier circuit 103B When the reset operation, the accumulation operation, and the selection operation are performed in the first amplifier circuit 103A, In the second period, the operation in the first amplifier circuit 103A and the operation in the second amplifier circuit 103B are performed. The operation of the amplifier circuit 103B may be performed in parallel with the operation of the amplifier circuit 103B.

[0099] As described above, in the configuration of this embodiment, the first photodiode, which is a visible light sensor, a photodetector including a first photodiode and a second photodiode serving as an infrared light sensor, arranged in parallel; In this case, the area required for each sensor can be shared, making it possible to reduce the area required for each sensor. As a result, the area required for arranging each sensor can be reduced, which leads to a reduction in pixel size. Therefore, it is possible to provide a light detection device in which the area of ​​each sensor is relatively large. This can improve the sensitivity of each sensor to visible light and infrared light. do.

[0100] In the configuration of this embodiment, the semiconductor layer of the first photodiode, which is a visible light sensor, Amorphous silicon absorbs visible light incident from the outside and transmits infrared light incident from the outside. As a result, visible light is transmitted to the second photodiode, which is an infrared light sensor. Therefore, the crystalline silicon can be used as a semiconductor layer to detect infrared light. In the case of the second photodiode configured as This eliminates the need for a separate optical filter on the second photodiode to reduce noise, resulting in reduced manufacturing costs. This allows for a reduction in manufacturing costs.

[0101] (Embodiment 2) In this embodiment, in addition to the plurality of photodetectors arranged in a matrix, An example of the configuration of a display device having a plurality of display elements arranged in a matrix will be described. Such a display device is called an optical touch panel, and the display screen also serves as an information input area. The configuration of the photodetector and the connection configuration between the photodetectors are the same as those shown in the first embodiment. The operation of the photodetector can be the same as that shown in Embodiment 1. can be performed in the same way.

[0102] 5 shows a circuit diagram of a part of the configuration of the display device. In FIG. 5, a pixel 520 is composed of four display elements. The pixel 520 is a basic configuration, and the pixel 520 are arranged in a matrix of m rows and n columns to form a display screen that also serves as an information input area. In FIG. 5, the photodetector 101 having the configuration shown in FIG. 1(A) is used for the pixel 520. The number of display elements 521 and photodetectors 101 in each pixel is The arrangement density of the plurality of photodetectors and the plurality of display elements is not limited to the form shown in FIG. They may be the same or different. In other words, one photodetector is used for one display element. One photodetector may be arranged for two or more display elements. Alternatively, one display element may be arranged for two or more photodetectors.

[0103] In the configuration shown in FIG. 5, a display element 521 includes a liquid crystal element 522. The element 521 includes a liquid crystal element 522 and a circuit such as a transistor that controls the operation of the liquid crystal element 522. Specifically, in FIG. 5, a display element 521 includes a liquid crystal element 522 and a switch. 523 and a capacitor 524. The liquid crystal element 522 includes a pixel electrode, a counter electrode, and a liquid crystal layer between the pixel electrode and the counter electrode. The liquid crystal layer has a voltage applied thereto.

[0104] The gate electrode of the transistor 523 is connected to the scanning line GL (GL1, GL2). The first terminal of the transistor 523 is connected to the signal line SL (SL1, SL2). The two terminals are connected to the pixel electrodes of the liquid crystal element 522. One of the electrodes is connected to the pixel electrode of the liquid crystal element 522, and the other is a wiring to which a fixed potential is applied. A potential corresponding to the image to be displayed is input to the signal line SL. When the transistor 523 is turned on by the signal of the scanning line GL, the potential of the signal line SL becomes The voltage applied to one of the pair of electrodes of the capacitor 524 and the pixel electrode of the liquid crystal element 522 is The capacitor element 524 holds a charge corresponding to the voltage applied to the liquid crystal layer. By applying a voltage, the polarization direction of the liquid crystal layer changes, and this is used to create a gradation of light passing through the liquid crystal layer. The light that passes through the liquid crystal layer contains visible light irradiated from the backlight. Use light.

[0105] In the configuration shown in FIG. 5, the operation of the display elements arranged in a matrix is ​​performed by a known method. The display device can be the same as that of the above.

[0106] The transistor 523 is manufactured in the same process as the transistor included in the photodetector 101. As a result, the manufacturing process of the display device can be simplified.

[0107] This embodiment mode can be freely combined with other embodiment modes.

[0108] (Embodiment 3) The photodetector according to one aspect of the present invention can improve the sensitivity of the sensor and reduce manufacturing costs. It has the following characteristics.

[0109] The photodetector according to one aspect of the present invention can be used in a display device, a notebook personal computer, a recording device, and the like. Image playback device equipped with a medium (typically DVD: Digital Versatile (Devices with a display that can play back recording media such as discs and display the images) In addition, the photodetector according to one embodiment of the present invention can be used in Sub-devices include mobile phones, portable game consoles, personal digital assistants, e-books, video cameras, Digital still camera, goggle-type display (head-mounted display), navigation audio systems, audio playback devices (car audio, digital audio players, etc.) , copiers, facsimiles, printers, printer-combined machines, automated teller machines (A TM), vending machines, etc. Specific examples of these electronic devices are shown in Figure 6.

[0110] FIG. 6A shows a display device, which includes a housing 5001, a display portion 5002, a support base 5003, etc. The photodetector according to one embodiment of the present invention can be used in the display portion 5002. By using a photodetector according to one embodiment of the present invention in 5002, the sensitivity of the sensor can be improved. It is possible to provide a display device that can reduce manufacturing costs. This includes all information display devices such as those for personal computers, TV broadcast reception, and advertising displays. It can be enjoyed.

[0111] FIG. 6B shows a portable information terminal, which includes a housing 5101, a display portion 5102, operation keys 5103, etc. The photodetector according to one embodiment of the present invention can be used in the display portion 5102. The sensitivity of the sensor is improved by using the photodetector device according to one embodiment of the present invention in the display portion 5102. This makes it possible to provide a portable information terminal that can reduce manufacturing costs.

[0112] FIG. 6C shows an automated teller machine, which includes a housing 5201, a display unit 5202, and a coin insertion slot. 5203, bill insertion slot 5204, card insertion slot 5205, bankbook insertion slot 5206, etc. The photodetector according to one embodiment of the present invention can be used in the display portion 5202. By using the photodetector according to one embodiment of the present invention in the sensor 5202, the sensitivity of the sensor can be improved. It is possible to provide an automated teller machine that can reduce manufacturing costs.

[0113] FIG. 6D shows a portable game machine, which includes a housing 5301, a housing 5302, a display portion 5303, and a display panel. display unit 5304, microphone 5305, speaker 5306, operation keys 5307, style The photodetector according to one embodiment of the present invention includes a display portion 5303 or a display The display unit 5303 or the display unit 5304 can be used as one of the display devices of the present invention. By using the photodetector according to the embodiment, the sensitivity of the sensor can be improved and the manufacturing cost can be reduced. It is possible to provide a portable game machine that can play the game. The display unit 5303 and the display unit 5304 are the same as those of the portable game machine. The number of display units is not limited to this.

[0114] This embodiment mode can be implemented in appropriate combination with any of the above embodiment modes.

[0115] (Fourth embodiment) In the configuration disclosed in the first embodiment, the first transistor 104A and the first transistor The transistor 104B is preferably configured using a transistor with extremely low off-state current. With this configuration, the first photodiode 102A and the second photodiode 1 The retention characteristics of the charge accumulated in response to the photocurrent in the O2B can be improved. Therefore, the detection accuracy of the photodetector 101 can be improved. When the global shutter method is used as the driving method for the device, the charge in each photodetector is The above structure is preferable because the retention periods are different. To achieve this, the semiconductor layers of the first transistor 104A and the second transistor 104B are For example, the semiconductor layer may be made of an oxide semiconductor, which is a wide-gap semiconductor. It is preferable.

[0116] The oxide semiconductor used in the oxide semiconductor layer is a quaternary metal oxide, In-Sn- Ga-Zn oxides, ternary metal oxides such as In-Ga-Zn oxides, In-Sn -Zn oxide, In-Al-Zn oxide, Sn-Ga-Zn oxide, Al-Ga- Zn-based oxide, Sn-Al-Zn-based oxide, In-Hf-Zn-based oxide, In-La-Z n-based oxides, In-Ce-Zn-based oxides, In-Pr-Zn-based oxides, In-Nd-Zn oxides, In-Sm-Zn oxides, In-Eu-Zn oxides, In-Gd-Zn oxides Oxides, In-Tb-Zn oxides, In-Dy-Zn oxides, In-Ho-Zn oxides oxides, In-Er-Zn oxides, In-Tm-Zn oxides, In-Yb-Zn oxides In-Lu-Zn ​​oxides, binary metal oxides such as In-Zn oxides, Sn- Zn-based oxides, Al-Zn-based oxides, Zn-Mg-based oxides, Sn-Mg-based oxides, In- Mg-based oxides, In-Ga-based oxides, indium oxide, tin oxide, zinc oxide, etc. In addition, SiO2 may be included in the above materials. -Ga-Zn oxides are oxides containing indium (In), gallium (Ga), and zinc (Zn). The composition ratio is not particularly important. The oxide semiconductor layer may be single-crystal or non-single-crystal. In the case of non-single crystal, it may be amorphous or polycrystalline. The structure may include a portion having the above structure, or may be non-amorphous.

[0117] In the configuration disclosed in the first embodiment, the first transistor 104A and the second transistor When the semiconductor layer of the photodiode 104B is made of an oxide semiconductor, for example, a second photodiode is formed on the substrate. Diode 102B, second transistor 105A, second transistor 105B, and third The first transistor 106A and the third transistor 106B are formed, and the second photodiode The second transistor 102B, the second transistor 105A, the second transistor 105B, and the third transistor A first insulating film is formed on the first transistor 106A and the third transistor 106B. A first transistor 104A and a second transistor 104B are formed on the insulating film. A second insulating film is formed on the first transistor 104A and the first transistor 104B. The second photodiode 102B may be formed on the second insulating film. do.

[0118] This embodiment mode can be implemented in appropriate combination with any of the above embodiment modes. [Explanation of symbols]

[0119] 101 Photodetector 102A First Photodiode 102B Second Photodiode 103A First Amplifier Circuit 103B Second amplifier circuit 104A First Transistor 104B first transistor 105A second transistor 105B second transistor 106A Third Transistor 106B Third transistor 107 Transfer control line 108 Power line 109 Selection control line 110A First output signal line 110B Second output signal line 111 Reset control line 200 Transparent substrate 201 Light blocking layer 202 Base film 203 p-type semiconductor region 204 i-type semiconductor region 205 n-type semiconductor region 206 i-type semiconductor region 207 n-type semiconductor region 208 i-type semiconductor region 209 n-type semiconductor region 210 Insulating layer 211 Gate electrode 212 gate electrode 213 Insulating Layer 214 Conductive layer 215 Conductive Layer 216 Conductive Layer 217 Conductive Layer 218 p-type semiconductor region 219 i-type semiconductor region 220 n-type semiconductor region 221 Insulating layer 222 Conductive layer 223 n-type semiconductor region 224 Conductive Layer 261 Conductive Layer 300 Backlight 301 Liquid crystal layer 302 Opposing substrate 303 Object to be detected 304 dashed arrow 305 dashed arrow 306 Light source 307 Light guide plate 308 Fixed material 520 pixels 521 Display element 522 Liquid crystal element 523 Transistor 524 Capacitor 5001 Case 5002 Display section 5003 Support stand 5101 Housing 5102 Display section 5103 Operation key 5201 Case 5202 Display section 5203 Coin slot 5204 Bill slot 5205 Card slot 5206 Passbook slot 5301 Housing 5302 Housing 5303 Display section 5304 Display section 5305 Microphone 5306 Speaker 5307 Operation key 5308 Stylus

Claims

[Claim 1] a first photodiode for detecting visible light, a second photodiode for detecting infrared light, a first amplifier circuit for amplifying and outputting charges accumulated in accordance with a photocurrent in the first photodiode, and a second amplifier circuit for amplifying and outputting charges accumulated in accordance with a photocurrent in the second photodiode; the semiconductor layer of the first photodiode is made of amorphous silicon; the semiconductor layer of the second photodiode is made of crystalline silicon; the first photodiode and the second photodiode are provided to overlap each other such that the first photodiode is located on a side on which incident light including the visible light and the infrared light is incident, the first photodiode absorbs the visible light and transmits the infrared light of the incident light; a second photodiode that absorbs the infrared light that is transmitted through the first photodiode from the incident light;

Images