JP2009295777A - Semiconductor device, electro-optical device, and electronic apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To achieve a semiconductor device which has an improved detection precision by increasing a response speed of an optical sensor element. <P>SOLUTION: A first p-type semiconductor region 532-1 as a first conduction region connected to a detection circuit 510 and a second p-type semiconductor region 532-1 as the first conductive region are constituted so that areas of these regions may be smaller than areas of first to third n-type semiconductor regions 533-1 to 533-3 as a second conductive region connected to power supply wiring 521. Concretely, they are constituted so that the number of sub-regions constituting the first conductive region may be smaller than that of the second conductive region. The first conductive region is composed of an n-type semiconductor and the second conductive region is composed of a p-type semiconductor, whereby the occurrence of potential gradient is suppressed. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a semiconductor device, an electro-optical device including the semiconductor device, and an electronic apparatus including the electro-optical device.

  2. Description of the Related Art In recent years, technology for mounting an optical sensor function on a substrate has been developed in an electro-optical device, particularly in a liquid crystal display device using a thin film transistor (for example, Patent Document 1). The purpose of installing the optical sensor function is (1) to reduce the power consumption and improve the image quality by measuring the external light and adjusting the brightness, etc. (2) to measure the backlight and adjust the brightness or chromaticity, ( 3) There are three ways to recognize the position of a finger or light pen and use it as a touch key. Examples of photosensor elements formed on the substrate include thin film transistors, PIN (P-Intrinsic-N) diodes, and PN diodes. In any case, the light receiving part is a silicon thin film, which increases manufacturing costs. Therefore, it is desirable that the silicon thin film constituting the switching element of the display pixel and the peripheral drive circuit is manufactured in the same manufacturing process.

JP 2006-118965 A

  One of the requirements for the optical sensor is a detection time (or detection cycle). That is, it is preferable that the time from the start of detection to the output of the result is shorter, because feedback is performed more quickly. The main factor that determines the detection time is the ratio of the output current of the photosensor element to the capacity of the inside of the photosensor element and the output wiring. The larger the current output from the photosensor element, the more the inside of the photosensor element and the output wiring The detection time is shortened as the capacity of is smaller. However, it is difficult to increase the photocurrent in a photosensor element formed using a silicon thin film formed on a glass substrate. Further, the capacitance of the inside of the optical sensor element and the output wiring can be reduced by narrowing the wiring width, but this method is a contradiction factor with the electrical resistance of the wiring. When the electric resistance is increased, a potential gradient is generated by the current flowing through the photosensor element, which causes a problem that the accuracy is deteriorated particularly at high illuminance.

  The present invention includes an optical sensor element (corresponding to the optical sensor element 501 in the present embodiment), a detection wiring connected to the optical sensor element (corresponding to the detection wiring 522 in the present embodiment), and the detection A detection circuit for detecting the potential or current of the wiring (in this embodiment, the detection circuit 510 corresponds) and a power supply wiring for supplying a power supply potential to the photosensor element (in this embodiment, the power supply wiring 521 corresponds) On the substrate (corresponding to the active matrix substrate 101 in this embodiment), the optical sensor element is formed of a conductive layer formed on the substrate, and is connected to the detection wiring. 1 conductive region (in this embodiment, the first p-type semiconductor region 532-1, the second p-type semiconductor region 532-2, or the fourth n-type semiconductor A region 542-1 and a fifth n-type semiconductor region 542-2, and a second conductive region connected to the power supply wiring (in this embodiment, the first n-type semiconductor region to the third n-type semiconductor region). n-type semiconductor regions 533-1 to 533-3, or third p-type semiconductor regions to sixth p-type semiconductor regions 543-1 to 543-4). A semiconductor device (corresponding to the active matrix substrate 101 in this embodiment) is proposed in which the area of the conductive region is smaller than the area of the second conductive region.

  With this configuration, since the capacitance of the first conductive region connected to the detection circuit can be reduced and the capacitance of the second conductive region can be increased, the detection time by the detection circuit can be shortened. Can do. The electrical resistance between the first conductive region and the detection circuit increases as the area of the first conductive region is reduced. On the other hand, the area of the second conductive region is increased. Since the resistance can be lowered, the potential gradient deterioration due to the electrical resistance can be avoided as a whole, and both the detection time and accuracy can be achieved.

  In the present invention, the first conductive region may include a plurality of first sub-regions (in this embodiment, the first p-type semiconductor region 532-1, the second p-type semiconductor region 532-2, or the first sub-region, 4 n-type semiconductor region 542-1 and fifth n-type semiconductor region 542-2 correspond to each other, and the second conductive region (in this embodiment, the first n-type semiconductor region ~ The third n-type semiconductor regions 533-1 to 533-3 or the third p-type semiconductor regions to the sixth p-type semiconductor regions 543-1 to 543-4 correspond to the plurality of second sub The semiconductor device is divided into regions, and the number of the plurality of first sub-regions is smaller than the number of the plurality of second sub-regions.

  With this configuration, the area of the first conductive region and the area of the second conductive region can be easily adjusted. In particular, when the optical sensor element is configured by a diode or a transistor, a layout area is obtained by arranging a light receiving portion between the first sub-region and the second sub-region arranged in a comb shape with a constant channel width. Thus, the area of the first conductive region can be easily made smaller than the area of the second conductive region while shrinking. Here, the light receiving portion is, for example, a region where a depletion layer of a diode or a transistor spreads (in this embodiment, a first intrinsic semiconductor region to a fourth intrinsic semiconductor region 530-1 to 530-4 as an intrinsic semiconductor, a fifth Intrinsic semiconductor region to eighth intrinsic semiconductor region 540-1 to 540-4).

  In the present invention, the first conductive region and the second conductive region are a light-shielding electrode for shielding the light sensor element (in this embodiment, the light-shielding electrode 560 corresponds), or the light sensor. Planarly through a transparent electrode for shielding the element (in this embodiment, the transparent electrode 570 corresponds) and an insulating layer (in this embodiment, the interlayer insulating film 580 and the interlayer insulating film 590 correspond). It is characterized by overlapping.

  The light sensor element including the light shielding electrode and the transparent electrode formed in such a manner can measure external light without being affected by the backlight due to the presence of the light shielding electrode, or the presence of the transparent electrode. Can shield electromagnetic noise from the display area and the like, and can perform measurement with higher accuracy, but the detection speed is slowed down by the capacitance between the first conductive area and the light-shielding electrode or the transparent electrode. There is a structural problem. However, since the capacitance is substantially proportional to the area of the first conductive region, application of the present invention can suppress the occurrence of a problem and has a great effect.

  It is also proposed that the photosensor element comprises a diode or a transistor, the first conductive region is an n-type silicon thin film, and the second conductive region is a p-type silicon thin film. Since the n-type silicon thin film can have a lower resistance than the p-type silicon thin film if the film thickness and the film quality are the same, even if the area of the first conductive region is smaller than the area of the second conductive region, the potential gradient is reduced. Can be small.

  The present invention also relates to an electro-optical device using the above-described semiconductor device (in this embodiment, the liquid crystal display device 910 corresponds), and an electronic device using the electro-optical device (in this embodiment, the electronic device 1000 includes Corresponding). With such a configuration, it is possible to realize better responsiveness when performing brightness adjustment, finger detection, backlight detection, and the like with the optical sensor element, and accuracy does not decrease.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, embodiments of the invention will be described with reference to the drawings.

[First Embodiment]
FIG. 1 is a perspective configuration diagram (partially sectional view) of a liquid crystal display device 910 according to the present embodiment. The liquid crystal display device 910 includes an active matrix substrate 101 and a counter substrate 912 that are bonded to each other with a sealant 923 at a predetermined interval, and a nematic liquid crystal material 922 is sandwiched therebetween. Although not shown, an alignment material made of polyimide or the like is applied on the active matrix substrate 101 and rubbed to form an alignment film. Further, although not shown, the counter substrate 912 is formed with a color filter corresponding to a pixel and a black matrix made of a low-reflection / low-transmittance resin for preventing light leakage and improving contrast. An alignment material made of polyimide or the like is applied to the surface in contact with the nematic liquid crystal material 922, and is rubbed in a direction parallel to and opposite to the alignment film rubbing treatment direction of the active matrix substrate 101.

  Further, an upper polarizing plate 924 is disposed on the outer plane of the counter substrate 912, and a lower polarizing plate 925 is disposed on the outer side of the active matrix substrate 101, so that their polarization directions are orthogonal to each other (crossed Nicols). . Further, a backlight unit 926 and a light guide plate 927 are disposed below the lower polarizing plate 925, and light is emitted from the backlight unit 926 toward the light guide plate 927, and the light guide plate 927 emits light from the backlight unit 926. It functions as a light source of the liquid crystal display device 910 by reflecting and refracting light so that it becomes a vertical and uniform surface light source toward the active matrix substrate 101. The backlight unit 926 is an LED unit in the present embodiment, but may be a cold cathode fluorescent lamp (CCFL). The backlight unit 926 is connected to the electronic apparatus 1000 main body through the connector 929 and supplied with PWM wave power. In this embodiment, the light amount of the backlight unit 926 is adjusted by appropriately adjusting the duty ratio of the PWM wave. Has a function to be adjusted. Although not shown, if necessary, the periphery may be covered with an outer shell, or a protective glass or acrylic plate may be attached further above the upper polarizing plate 924, and optical for improving the viewing angle. A compensation film may be attached.

  Further, the active matrix substrate 101 is provided with an overhang portion 110 that protrudes from the counter substrate 912, and an FPC (flexible substrate) 928 and a driving IC 921 are mounted on the overhang portion 110 and provided on the overhang portion 110. Are electrically connected through the connected terminals. The drive IC 921 supplies signals and power necessary for driving the active matrix substrate 101. The FPC 928 is connected to the electronic device 1000 main body, and supplies necessary signals and power from the external power supply circuit 784 and the video processing circuit 780 (see FIG. 4) to the drive IC 921 and the active matrix substrate 101. In the present embodiment, so-called COG (Chip On Glass) mounting in which the driving IC 921 is mounted on the overhanging portion 110 is used. However, the present invention is not limited thereto, and only the FPC 928 is mounted on the overhanging portion 110 and the driving IC 921 is mounted. May be so-called COF (Chip On Film) mounting mounted on the FPC 928.

  An optical sensor opening 120 is provided on the liquid crystal display device 910. The photosensor openings 120 are provided at the corners of the periphery of the display area, and the black matrix on the counter substrate 912 that overlaps the photosensor openings 120 in a plan view is removed to form openings. In addition, a photosensor element 501 is provided on the active matrix substrate 101 that overlaps the photosensor opening 120 in a plan view (see FIG. 2). In this embodiment, the number of the optical sensor openings 120 is one, but a plurality may be provided.

  FIG. 2 is a configuration diagram of the active matrix substrate 101. On the active matrix substrate 101, 480 scanning lines 201 (201-1 to 201-480) and 1920 data lines 202 (202-1 to 202-1920) are formed orthogonally. The scanning lines 201-1 to 201-480 are connected to the scanning line driving circuit 301 and driven appropriately. The data lines 202-1 to 202-1920 are connected to the data line driving circuit 302 and are appropriately driven.

  On the active matrix substrate 101, a photo sensor element 501 is formed in a region overlapping the photo sensor opening 120 in FIG. 1 (details will be described later with reference to FIG. 6). The optical sensor element 501 is connected to the power supply wiring 521 and the detection wiring 522, and the detection wiring 522 is connected to the detection circuit 510.

  The thin film transistors constituting the scanning line driving circuit 301, the data line driving circuit 302, and the detection circuit 510 are manufactured in the same manner as a pixel switching element 401 (401-nm), which will be described later, by SOG (silicon on glass) technology. The active matrix substrate 101 is a so-called active matrix substrate with a built-in driving circuit. The scan line driver circuit 301, the data line driver circuit 302, the detection circuit 510, and the power supply wiring 521 are connected to a mounting terminal 320 that is a plurality of signal input terminals. The mounting terminal 320 is disposed on the projecting portion 110 and is connected to the driving IC 921 or the FPC (flexible substrate) 928 to be supplied with a necessary signal or power supply potential.

  FIG. 3 is a circuit diagram in the vicinity of the intersection of the mth data line 202-m and the nth scanning line 201-n in the display area 310. A pixel switching element 401-nm is formed of an n-channel field effect polysilicon thin film transistor at each intersection of the scanning line 201-n and the data line 202-m, and the gate electrode thereof is the scanning line 201-m. n, the source / drain electrodes are connected to the data line 202-m and the pixel electrode 402 (402-nm), respectively. The pixel electrode 402-nm forms an auxiliary capacitor by sandwiching a common electrode (COM) 930 and a dielectric, and when assembled as a liquid crystal display device, the common electrode is sandwiched by nematic phase liquid crystal material 922. (COM) 930 and a capacitor are also formed. Here, the common electrode (COM) 930 is a transparent common electrode disposed on the entire display region 310 on the active matrix substrate 101, and forms a capacitor on each pixel electrode 402 -nm and the active matrix substrate 101. In addition, the liquid crystal display device is configured in a so-called IPS (In Plane Switching) mode in which an electric field is applied to the liquid crystal in a direction substantially parallel to the active matrix substrate 101. In the present embodiment, the common electrode (COM) 930 is AC driven to be inverted at a constant period. However, the common electrode (COM) 930 may be DC driven that always maintains a constant potential.

  FIG. 4 is a block diagram showing a specific configuration of the electronic apparatus 1000 in the present embodiment. The liquid crystal display device 910 is the liquid crystal display device 910 described with reference to FIG. 1, and the external power supply circuit 784 and the video processing circuit 780 send necessary signals and power through an FPC (flexible substrate) 928 and a connector 929. To supply. The central processing circuit 781 acquires input data from the input / output device 783 via the external I / F circuit 782. Here, the input / output device 783 is, for example, a keyboard, a mouse, a trackball, an LED, a speaker, an antenna, or the like. The central processing circuit 781 performs various arithmetic processing based on data from the outside, and transfers the result to the video processing circuit 780 or the external I / F circuit 782 as a command. The video processing circuit 780 updates the video information based on a command from the central processing circuit 781 and changes the signal to the liquid crystal display device 910, whereby the display video of the liquid crystal display device 910 changes.

  The detection signal of the optical sensor element 501 on the liquid crystal display device 910 is input to the detection circuit 510 connected via the detection wiring 522, and the detection circuit 510 outputs an output signal corresponding to the illuminance to the drive IC 921. . The drive IC 921 converts the output signal into illuminance data, and outputs the illuminance data to the central processing circuit 781 through an FPC (flexible substrate) 928. The central processing circuit 781 accesses a reference table 785 composed of an EEPROM (Electronically Erasable and Programmable Read Only Memory), and sets an appropriate value corresponding to the PWM wave duty supplied to the backlight unit 926 based on the input illuminance data. The data is converted again and transmitted to the external power supply circuit 784. The external power supply circuit 784 supplies a PWM wave having a duty corresponding to the transmitted value to the backlight unit 926 in the liquid crystal display device 910 through the connector 929. Since the luminance of the backlight unit 926 varies depending on the voltage supplied from the external power supply circuit 784, the luminance of the liquid crystal display device 910 when displaying all white also varies. Specifically, the electronic device 1000 includes a monitor, a TV, a notebook computer, a PDA (Personal Digital (Data) Assistants), a digital camera, a video camera, a mobile phone, a mobile photo viewer, a mobile video player, a mobile DVD player, For example, a portable audio player.

  FIG. 5 is a diagram illustrating a relational expression between the detected illuminance data of the external light set by the reference table 785 and the output of the backlight unit 926. In this way, the output of the backlight unit 926 is increased to increase the brightness of the display area as the illuminance of the external light increases, and the output of the backlight unit is set to the maximum when the illuminance of the external light is about 1500 lux. Therefore, it is possible to always display with brightness optimized for the illuminance of outside light, and it is possible to maintain good visibility regardless of outside light and reduce average power consumption. Note that the output of the backlight unit 926 here corresponds to the duty ratio of the power supply of the PWM waveform supplied from the external power supply circuit 784 to the backlight unit 926.

  FIG. 6 is a plan configuration diagram of the optical sensor element 501. This figure gives priority to legibility and the scale is not accurate. The optical sensor element 501 includes a first n-type semiconductor region 533-1, a first intrinsic semiconductor region 530-1, and a first p-type semiconductor region as a first conductive region in order from the detection circuit 510. 532-1, a second intrinsic semiconductor region 530-2, a second n-type semiconductor region 533-2, a third intrinsic semiconductor region 530-3, and a second p as a first conductive region. A type semiconductor region 532-2, a fourth intrinsic semiconductor region 530-4, and a third n-type semiconductor region 533-3 are arranged in a comb shape.

  Here, the first intrinsic semiconductor region to the fourth intrinsic semiconductor region 530-1 to 530-4 are thin film polysilicon having the same film thickness and film quality as those constituting the active layer of the pixel switching element 401 -nm. It is an intrinsic semiconductor in which no or almost no phosphorus ions or boron ions are implanted in the manufacturing process, each having a size of 200 μm in the X direction and 10 μm in the Y direction. Note that the X direction refers to the first intrinsic semiconductor region to the fourth intrinsic semiconductor region 530-1 to 530-4 and the first n-type semiconductor region to the third n-type semiconductor region as the n-type semiconductor region 533. 533-1 to 533-3 (second conductive region) and the junction line direction between the first p-type semiconductor region to the second p-type semiconductor region 532-1 to 532-2 as the p-type semiconductor region 532 The Y direction indicates a direction perpendicular to the Y direction.

  The first p-type semiconductor region to the second p-type semiconductor region 532-1 to 532-2 (first conductive region) are the same films that constitute the active layer of the pixel switching element 401-nm. It is a p + type degenerate semiconductor consisting of an ohmic p-type silicon thin film having a sheet resistance of 1600 Ω / □, which is made of thin film polysilicon having a thickness and film quality, implanted with boron ions in the manufacturing process, and is 220 μm in the X direction, Y The direction is 4 μm in size.

  Further, the first n-type semiconductor region to the third n-type semiconductor region 533-1 to 533-3 (second conductive region) are the same films that constitute the active layer of the pixel switching element 401 -nm. It is an n + type degenerate semiconductor consisting of an ohmic n-type silicon thin film having a sheet resistance of 1000Ω / □, which is made of thin-film polysilicon having a thickness and quality, and in which phosphorus ions are implanted in the manufacturing process, and the X direction is 220 μm and the Y direction, respectively. Is 4 μm in size. With this configuration, the optical sensor element 501 is an element in which four PIN junction diodes having a channel width of 200 μm and a channel length of 10 μm are connected in parallel.

  Note that a degenerate semiconductor usually refers to a state in which the Fermi level interposed between the conduction band and the valence band is moved into the conduction band by adding a dopant. Indicates an ohmic junction even in contact with a dissimilar conductor.

  At this time, the first p-type semiconductor region to the second p-type semiconductor region 532-1 to 532-2 function as anode electrodes and are all connected to the detection wiring 522 through the contact holes. In addition, the first n-type semiconductor region to the third n-type semiconductor region 533-1 to 533-3 function as a cathode electrode and are connected to the power supply wiring 521 through a contact hole.

  In the present configuration example, the detection wiring 522 and the power supply wiring 521 are metal wirings configured by a laminated structure of molybdenum and an aluminum neodymium alloy.

  In addition, in a region overlapping the optical sensor element 501 in a plan view, a light-shielding electrode 560 made of a chromium thin film having a thickness of 200 nm and a display region 310 (FIG. 2) are provided in order to prevent backlight light from being applied to the optical sensor element 501. A transparent electrode 570 made of an ITO (Indium Tin Oxide) thin film having a thickness of 100 nm for blocking electromagnetic noise from the reference) overlaps in a planar manner. Here, the light shielding electrode 560 and the transparent electrode 570 are each grounded to the module GND.

  FIG. 12 is a cross-sectional view taken along A-A ′ of FIG. 6. As described above, the first p-type semiconductor region to the second p-type semiconductor region 532-1 to 532-2 (first conductive region) and the first n-type semiconductor region to the third n-type semiconductor region 533 are provided. The polysilicon thin film layer composed of -1 to 533-3 (second conductive region) and the first intrinsic semiconductor region to the fourth intrinsic semiconductor region 530-1 to 530-4 is a silicon oxide thin film having a thickness of 300 nm. The light-shielding electrode 560 is planarly overlapped with an interlayer insulating film 580 interposed therebetween, and the transparent electrode 570 is also planarly overlapped with an interlayer insulating film 590 made of a silicon oxide thin film having a thickness of 600 nm interposed therebetween.

  In this way, the light sensor element 501 is sandwiched between the light shielding electrode 560 and the transparent electrode 570 so that noise is reliably shielded, and external light is applied to the light sensor element 501. FIG. 7 is a circuit diagram of the detection circuit 510. The detection wiring 522 connected from the optical sensor element 501 is connected to one end of the capacitor C1, one end of the capacitor C3, and the drain electrode of the transistor NC, and the other end of the capacitor C3 is connected to the power source VSL. The source electrode of the transistor NC is connected to the power supply VSL, and the gate electrode is connected to the signal RST. The signal RST is also connected to one end of the capacitor C2 and the gate electrode of the transistor NR.

  The other end of the capacitor C1, the other end of the capacitor C2, the source electrode of the transistor NR, the gate electrode of the transistor N1, and the gate electrode of the transistor P1 are connected to the node A, the drain electrode of the transistor N1, the drain electrode of the transistor P1, and the transistor The drain electrode of NR, the gate electrode of transistor N2, and the gate electrode of transistor P2 are connected to node B. The drain electrode of transistor N2, the drain electrode of transistor P2, the gate electrode of transistor N3, and the gate electrode of transistor P3 are connected to node B. The drain electrode of the transistor N3, the drain electrode of the transistor P3, the gate electrode of the transistor N4, and the gate electrode of the transistor P4 are connected to the node D and connected to the transistor C3. The drain electrode of the transistor N4, the drain electrode of the transistor P4, and the drain electrode of the transistor N5 are connected to the signal OUT, the source electrode of the transistor P4 and the drain electrode of the transistor P5 are connected, and the gate electrode of the transistor N5 and the transistor P5 The gate electrode is connected to the signal RST.

  The source electrodes of the transistors N1, N2, N3, N4, and N5 are connected to the power source VSL, and the source electrodes of the transistors P1, P2, P3, and P5 are connected to the power source VSH. The

  The transistor N1, the transistor N2, the transistor N3, the transistor N4, the transistor N5, the transistor NR, and the transistor NC are n-channel thin film transistors, and the transistor P1, the transistor P2, the transistor P3, the transistor P4, and the transistor P5 are p-channel thin films. It is a transistor.

  The power supply VSL, the power supply VSH, the signal RST, and the signal OUT are potentials or signals on the signal lines drawn from the mounting terminals 320, respectively. The power supply VSL, the power supply VSH, the signal RST, and the signal OUT are mounted on the driving IC 921 and supplied with the potential or signal, respectively. In this embodiment, the power supply VSL is always 0 V, the power supply VSH is always 5 V, and the power supply wiring 521 is always supplied with a 5 V potential from the drive IC 921 via the mounting terminal 320.

  8 and 9 are timing charts showing a sequence of illuminance detection by the optical sensor element 501 and the detection circuit 510. FIG. FIG. 8 is a chart when the light sensor element 501 is irradiated with light of low illuminance (100 lux), and FIG. 9 is a chart when the light sensor element 501 is irradiated with light of high illuminance (350 lux).

  The signal RST is a signal input from the driving IC 921 via the mounting terminal 320, and is always a pulse signal having a high potential of 5V, a low potential of 0V, a pulse length (high potential period) of 50 microseconds, and a period of 60 Hz regardless of the illuminance. It is.

  When the signal RST becomes a high potential (5 V), the transistor NC and the transistor NR are turned on, and the first p-type semiconductor region 532 to the second p-type semiconductor region 532 of the detection wiring 522 and the photosensor element 501 connected thereto. The potential (0 V) of the power supply VSL is charged in −1 to 532-2 (first conductive region), and a reverse bias of −5 V is applied to the PIN diode constituting the photosensor element 501. Further, the node A and the node B are short-circuited and charged with an intermediate potential (2.5 V in this embodiment) determined by the capability ratio of the transistor N1 and the transistor P1.

  When the signal RST becomes a low potential (0 V) after 50 μs, the transistor NC and the transistor NR are turned off, and the detection wiring 522 and the first p-type semiconductor region to the second p-type semiconductor of the photosensor element 501 connected thereto. Regions 532-1 to 532-2 are disconnected from power supply VSL. Further, the node A and the node B are also electrically disconnected, the node A is in a floating state without potential supply, and at the same time as the potential of the signal RST is lowered by the capacitive coupling of the capacitor C2, approximately 5 × C2 ÷ C1 volts (this embodiment) In the example, the potential drops below the intermediate potential (2.5V) by adjusting the capacitances of the capacitors C1 and C2 so as to be 0.5V (therefore, the node A is 2.0V at the moment when the signal RST becomes LOW). ). At this time, the node B is about 5 V (4.5 V in this embodiment), the node C is about 0 V (0.1 V in this embodiment), and the node D is about 5 V (4.99 V in this embodiment). And 0V is output as the signal OUT.

  Thereafter, the potentials of the detection wiring 522 and the first p-type semiconductor region to the second p-type semiconductor region 532-1 to 532-2 (first conductive region) of the optical sensor element 501 connected thereto are measured by the optical sensor. It gradually rises with the photocurrent of the element 501. The rising speed at this time is proportional to the illuminance of external light applied to the optical sensor element 501, and each load of the detection wiring 522, the first p-type semiconductor region 532-1, and the second p-type semiconductor region 532-2. It is inversely proportional to the sum of the capacity and the capacity of the capacitor C3. That is, with the same circuit configuration / layout, the higher the illuminance, the faster the potential rise rate of the detection wiring 522. At this time, the potential of the node A similarly rises due to capacitive coupling with the capacitor C1. In this embodiment, the capacitance of the capacitor C1 is as large as 10 pF, and the capacitance 1 pF of the capacitor C2 and the load capacitance of each transistor and wiring constituting the detection circuit 510 can be ignored. Is almost the same. Here, when the node A exceeds the intermediate potential of 2.5 V, the potentials of the node B, the node C, the node D, and the signal OUT are inverted.

  The driving IC 921 periodically checks the potential of the signal OUT, and can measure the time t1 until it is inverted to convert it into illuminance. In a region where the photocurrent is sufficiently large and the thermal current and leakage current can be ignored, the time t1 until inversion is inversely proportional to the illuminance. In this embodiment, the time t1 until reversal is 350 microseconds when the illuminance is 100 lux as shown in FIG. 8, and the time t1 until reversal is 100 microseconds when the illuminance is 350 lux as shown in FIG. 9, and this time t1 is measured. Thus, the driving IC 921 calculates the illuminance applied to the optical sensor element 501 and transmits the information to the central processing circuit 781 via the FPC 928. After that, as described in the explanation of FIG. 5, the liquid crystal display device 910 is always kept in a good visibility state by setting the backlight luminance according to the illuminance.

  Here, the detection time of the detection circuit 510 is the time t1 described with reference to FIGS. As described above, the time t1 is proportional to the photocurrent, and the load capacitance of the detection wiring 522, the first p-type semiconductor region to the second p-type semiconductor region 532-1 to 532-2 (first conductive region) and , Inversely proportional to the sum of the capacities of the capacitors C3.

  Increasing the photocurrent is not easy because the manufacturing process of the photosensor element 501 is the same as that of the pixel switching element 401-nm. On the other hand, since the detection wiring 522 is a metal wiring and does not need to be overlapped with the light shielding electrode or the transparent electrode, it can be formed thin (2 μm in this embodiment) to the manufacturing process limit. The capacity can be easily reduced. Further, since the capacity of the capacitor C3 is also a design parameter, it can be set to zero.

  Therefore, in order to shorten the detection time, the load capacity of the first conductive region becomes a problem. The capacitance of the thin film conductive layer generally increases monotonously with respect to the area. In this embodiment, the interlayer insulating film between the light-shielding electrode or transparent electrode formed in a superimposed manner and the conductive region has a relatively thin film thickness of about 500 nm, and thus the capacitance may be considered to be substantially proportional to the area. Therefore, the area of the first conductive region may be reduced in order to reduce the load capacity. The area of the conductive region is represented by the product of the lengths in the X direction and the Y direction in plan view.

  On the other hand, the area of the first p-type semiconductor region to the second p-type semiconductor region 532-1 to 532-2 (first conductive region) and the first n-type semiconductor region to the third n-type semiconductor region. As the area of 533-1 to 533-3 (second conductive region) is reduced, the photocurrent decreases or the potential fluctuation increases.

  That is, when the X-direction size of each region is shortened, the junction length between the first intrinsic semiconductor region to the fourth intrinsic semiconductor region 530-1 to 530-4 is also shortened, and the effective channel width of the PIN diode is reduced. As a result, the photocurrent decreases.

  On the other hand, when the size in the Y direction of each region is shortened or the number of regions is decreased, the density of current flowing in each region increases in inverse proportion to it. A voltage gradient is generated in each conductive region by the product of this current density and resistance, and the reverse bias applied to the intrinsic semiconductor region of the PIN diode varies depending on the region, resulting in an error in the photocurrent. Since this voltage gradient is proportional to the illuminance, that is, the photocurrent, the error increases as the illuminance increases. At this time, the voltage gradient is generated in the first conductive region and the second conductive region equally according to the resistance and the current density.

  Here, since the performance of the second conductive region connected to the power supply wiring 521 does not change even when the load capacitance increases, the area of the second conductive region is increased and the current density of the second conductive region is decreased. Even so, there is no trade-off. Therefore, by increasing the area of the second conductive region, errors are suppressed and detection accuracy is not deteriorated. In addition, when the area of the first conductive region is increased, the load capacity increases and the detection time increases. Therefore, if the area of each region is reduced to the limit where the voltage gradient can be tolerated, or if the number of regions is reduced, the optimum design can be achieved. Become.

  According to the configuration of the present embodiment, the anode electrode constituting the photosensor element 501, that is, the first p-type semiconductor region to the second p-type semiconductor region 532-1 to 532-2 (first conductive region) is Compared with the cathode electrode, that is, the first n-type semiconductor region to the third n-type semiconductor region 533-1 to 533-3 (second conductive region), the size of each region is the same, but the number of regions Is one less. With this configuration, a PIN diode can be easily formed simply by sandwiching an intrinsic semiconductor between a p-type semiconductor region and an n-type semiconductor region, so that there is no extra routing and the resistance value and capacitance value can be minimized. In addition, since the area of the first conductive region can be configured to be smaller than the area of the second conductive region, a photosensor element that has a high detection speed and is unlikely to cause an error as described above can be built in the display device. In this embodiment, the p-type semiconductor region is composed of two regions and the n-type semiconductor is composed of three regions. Of course, the p-type semiconductor region is composed of n regions and the n-type semiconductor is represented by n + 1 with an arbitrary integer n. You may comprise so that it may become an area | region.

  Further, as a configuration of the optical sensor element, a configuration may be used in which a reference element shielded in order to remove the thermal current is placed, a current difference is taken, and a difference in detection time between the two is detected. The same effect can be obtained if the area of the conductive region connected to the detection circuit is made smaller than the area of the conductive region connected to the power source.

[Second Embodiment]
FIG. 10 is a plan configuration diagram of the photosensor element 502 according to the second embodiment. Priority is given to the ease of viewing the figure, and the scale is not accurate. The active matrix substrate 101 in this embodiment is completely the same as the active matrix substrate 101 described in the first embodiment except that the optical sensor element 501 is replaced with the optical sensor element 502 and the detection circuit 510 is replaced with a detection circuit 520 described later. Since it is the same, description is abbreviate | omitted. Also, the configuration of the liquid crystal display device and the electronic apparatus 1000 is not different from the first embodiment except for the above points, and the description thereof will be omitted.

  The optical sensor element 502 includes a third p-type semiconductor region 543-1, a fifth intrinsic semiconductor region 540-1, and a fourth n-type semiconductor region as a first conductive region in order from the detection circuit 520. 542-1, a sixth intrinsic semiconductor region 540-2, and a fourth p-type semiconductor region 543-2 are arranged side by side, and a fifth p-type semiconductor region 543-3 and a seventh intrinsic semiconductor are sequentially arranged. A region 540-3, a fifth n-type semiconductor region 542-2 as a first conductive region, an eighth intrinsic semiconductor region 540-4, and a sixth p-type semiconductor region 543-4 are arranged. . The fourth p-type semiconductor region 543-2 and the fifth p-type semiconductor region 543-3 are regions isolated from each other, and a gap of 5 μm is provided therebetween.

  Here, the fifth to eighth intrinsic semiconductor regions 540-1 to 540-4 as the intrinsic semiconductor region 540 have the same thickness as that constituting the active layer of the pixel switching element 401 -nm. It is an intrinsic semiconductor made of thin-film polysilicon having a film quality, in which no or almost no phosphorus ions or boron ions are implanted in the manufacturing process, each having a size of 200 μm in the X direction and 10 μm in the Y direction. Here, the X direction means the fourth n-type semiconductor region to the fifth n-type as the n-type semiconductor region 542 of the fifth intrinsic semiconductor region to the eighth intrinsic semiconductor region 540-1 to 540-4. Junction lines between the semiconductor regions 542-1 to 542-2 and the third p-type semiconductor region to the sixth p-type semiconductor regions 543-1 to 543-4 (second conductive regions) as the p-type semiconductor region 543 The Y direction indicates a direction perpendicular to the direction. Further, the fourth n-type semiconductor region to the fifth n-type semiconductor region 542-1 to 542-2 (first conductive region) have the same film thickness as that constituting the active layer of the pixel switching element 401-nm. -It is an ohmic n-type degenerate semiconductor made of thin-film polysilicon having a film quality, implanted with phosphorus ions in the manufacturing process, and having a sheet resistance of 1000 Ω / □, each having a size of 220 μm in the X direction and 2.5 μm in the Y direction. is there. The third p-type semiconductor region to the sixth p-type semiconductor region 543-1 to 543-4 (second conductive region) have the same film thickness as that constituting the active layer of the pixel switching element 401 -nm. -It is an ohmic p-type degenerate semiconductor made of thin film polysilicon having a film quality, implanted with boron ions in the manufacturing process, and having a sheet resistance of 1600 Ω / □, each having a size of 220 μm in the X direction and 10 μm in the Y direction. .

  With this configuration, the optical sensor element 501 is an element in which four PIN junction diodes having a channel width of 200 μm and a channel length of 10 μm are connected in parallel. The optical sensor element 501 according to the first embodiment. The polarity is reversed compared to. At this time, the fourth n-type semiconductor region to the fifth n-type semiconductor region 542-1 to 542-2 function as cathode electrodes, and are all connected to the detection wiring 522 (first conductive region). The third p-type semiconductor region to the sixth p-type semiconductor regions 543-1 to 543-4 function as cathode electrodes and are connected to the power supply wiring 521 through contact holes (second conductive regions). Note that the detection wiring 522 and the power supply wiring 521 are not different from those of the first embodiment, and thus the same numbers are assigned and the description thereof is omitted. In addition, a light shielding electrode 560 for preventing backlight light from being irradiated on the optical sensor element 502 and a transparent electrode 570 for blocking noise from the outside are planar in areas overlapping the optical sensor element 502 in a plane. Similar to the optical sensor element 501 of the first embodiment, the optical sensor elements 501 overlap each other and are grounded to the module GND.

  FIG. 11 is a circuit diagram of the detection circuit 520 in the second embodiment. Compared to the detection circuit 510 in the first embodiment, the signal RST is replaced with the signal XRST, the signal OUT is replaced with the signal XOUT, the transistor NC is replaced with the transistor PC, its source electrode is connected to the power source VSH, and the transistor NR. Is replaced by transistor PR, transistor N4 and transistor P4 are replaced by transistor N6 and transistor P6, respectively, transistor N5 and transistor P5 are replaced by transistor N7 and transistor P7, respectively, and the drain electrode of transistor P6, the drain electrode of transistor P7, and transistor N6 Are connected to the signal XOUT, and the source electrode of the transistor P6 and the source electrode of the transistor P7 are connected to the power source. Is connected to the SH, the source electrode of the transistor N6 is connected to the drain electrode of the transistor N7, the source electrode of the transistor N7, configured is connected to the power supply VSL.

  The signal XRST and the signal XOUT are signals in which the polarities of the signal RST and the signal OUT described in FIGS. 8 and 9 of the first embodiment are inverted. Since other configurations are not different from the detection circuit 510 in the first embodiment, the description thereof is omitted. The difference between the detection circuit 520 and the detection circuit 510 corresponds to the fact that the polarities of the diodes are reversed in the optical sensor element 501 and the optical sensor element 502, and has a circuit configuration in which the operational polarity is completely reversed. Since the polarity is exactly the same with the polarity reversed, the description is omitted.

  Also in this configuration, the area of the first conductive region (the fourth n-type semiconductor region to the fifth n-type semiconductor region 542-1 to 542-2) connected to the detection circuit is the second conductive region ( The third p-type semiconductor region to the sixth p-type semiconductor region 543-1 to 543-4) are small, and the capacitance of the first conductive region is small and the circuit operation time is shortened. Is the same as in the first embodiment. Further, in this embodiment, the size of each isolated region of the third p-type semiconductor region to the sixth p-type semiconductor regions 543-1 to 543-4 constituting the second conductive region is the same as that of the first conductive region. The size is larger than the size of each isolated region of the fourth n-type semiconductor region to the fifth n-type semiconductor region 542-1 to 542-2, and further reduces the current density in the second conductive region. Because of such a configuration, the detection accuracy is superior to that of the first embodiment. Furthermore, in this embodiment, the first conductive region is constituted by an n-type degenerate semiconductor thin film, and the second conductive region is constituted by a p-type degenerate semiconductor thin film. When the first conductive region is made of an n-type semiconductor thin film, the sheet resistance of the n-type degenerate semiconductor thin film is generally lower than that of the p-type degenerate semiconductor thin film when manufactured in the normal manufacturing process with the same film thickness. The potential gradient can be made equal even if the area is made smaller than that of the p-type semiconductor thin film. For this reason, in this embodiment, the area of the first conductive region is reduced by 37.5% compared to the first embodiment (therefore, the detection speed is increased to about 2/3 of the first embodiment). Despite this, there is no accuracy loss due to this. As described above, the configuration of the present embodiment is further improved in detection speed and accuracy than the configuration of the first embodiment, but the circuit area is increased. Which one should be adopted should be comprehensively determined in consideration of the advantages and disadvantages of both.

  Note that in this embodiment, the optical sensor element includes two separated repeated regions (that is, a region including the fifth intrinsic semiconductor region 540-1 and the sixth intrinsic semiconductor region 540-2 as the intrinsic semiconductor region and the seventh intrinsic semiconductor region). Although the intrinsic semiconductor region 540-3 and the eighth intrinsic semiconductor region 540-4 are included), it is needless to say that it may be constituted by three or more repeating regions.

  In this embodiment, the optical sensor element is constituted by a PIN junction diode, but it is needless to say that it may be constituted by a thin film diode or a PN diode.

  The present invention is not limited to the above-described embodiments, but is used for liquid crystal display devices such as a vertical alignment mode (VA mode), a twisted nematic (TN) mode, and an FFS mode using a fringe electric field instead of the IPS mode. Alternatively, it may be used for an organic EL display (OLED). Moreover, not only a total transmission type but also a total reflection type and a reflection / transmission combined type may be used. Regarding the configuration of the data line driving circuit and the optical sensor element, not only the circuit configuration of this embodiment but also any known data line driving circuit or optical sensor element may be used.

  In addition, as an application example of the optical sensor element, the backlight brightness is changed according to the illuminance of the external light. For example, the display gamma characteristic is changed according to the illuminance of the external light, or the backlight or the organic EL For example, the luminance may be measured to feed back the change over time, or the device may have a key input function by detecting the shadow of a finger or stylus.

FIG. 6 is a perspective configuration diagram of a liquid crystal display device. 1 is a configuration diagram of an active matrix substrate. The pixel circuit diagram of an active matrix substrate. 1 is a block diagram illustrating an embodiment of an electronic device 1000. FIG. The graph which shows control of the backlight voltage by external light illumination intensity. The plane block diagram of the optical sensor element 501 in 1st Embodiment structure. FIG. 3 is a circuit diagram of a detection circuit in the first embodiment. The timing chart explaining operation | movement at the time of low illumination intensity. The timing chart explaining operation | movement at the time of high illumination intensity. The plane block diagram of the optical sensor element 502 in 2nd Embodiment. FIG. 5 is a circuit diagram of a detection circuit in the second embodiment. Sectional drawing along A-A 'of FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 101 ... Active matrix board | substrate, 201 ... Scan line, 202 ... Data line, 301 ... Scan line drive circuit, 302 ... Data line drive circuit, 501, 502 ... Photo sensor element, 510, 520 ... Detection circuit, 521 ... Power supply wiring, 522 ... detection wiring, 532,543 ... p-type semiconductor region, 533,542 ... n-type semiconductor region, 530,540 ... intrinsic semiconductor region, 401 ... pixel switching element, 402 ... pixel electrode, 910 ... liquid crystal display device, 921 ... Drive IC, 1000 ... electronic equipment.

Claims (6)

An optical sensor element;
A detection wiring connected to the photosensor element;
A detection circuit for detecting the potential or current of the detection wiring;
A semiconductor device having power supply wiring on a substrate for supplying a power supply potential to the photosensor element,
The photosensor element is
Comprising a conductive layer formed on the substrate, comprising a first conductive region connected to the detection wiring, and a second conductive region connected to the power supply wiring;
The area of the first conductive region is smaller than the area of the second conductive region. The first conductive region is divided into a plurality of first sub-regions;
The second conductive region is divided into a plurality of second sub-regions;
The number of the plurality of first sub-regions is
The semiconductor device according to claim 1, wherein the number is smaller than the number of the plurality of second sub-regions. The first conductive region and the second conductive region are:
The light-shielding electrode for shielding the said optical sensor element, or the transparent electrode for shielding the said optical sensor element, has overlapped planarly via the insulating layer. 2. The semiconductor device according to 2. The photosensor element includes a diode or a transistor,
The first conductive region is made of an n-type silicon thin film,
The semiconductor device according to any one of claims 1 to 3, wherein the second conductive region is formed of a p-type silicon thin film.   An electro-optical device using the semiconductor device according to claim 1.   An electronic apparatus using the electro-optical device according to claim 5.

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