JP2009164543A - Optical sensor and display device - Google Patents

Abstract

An optical sensor capable of reducing the parasitic capacitance inside the sensor without reducing the photocurrent generated inside the sensor.
An optical sensor according to the present invention is formed on a control electrode formed on a substrate, facing the control electrode through an insulating film, and positioned on both sides of the photoactive layer. And a semiconductor film 24 including a source electrode 26 and a drain region 27, the photoactive layer 25 is disposed in a region overlapping the control electrode 22, and the source electrode 26 is a low-concentration region overlapping the edge of the control electrode 22. The length L2 of 26L is shorter than the length L3 of the boundary portion between the low concentration region 26L and the photoactive layer 25.
[Selection] Figure 3

Description

  The present invention relates to an optical sensor using a thin-film semiconductor (hereinafter referred to as “semiconductor film”) and a display device including the same.

  Currently, a display device including an optical sensor is known. For example, in a liquid crystal display device, a thin film transistor (TFT) is used as a switching element for controlling driving of a pixel, and an optical sensor is formed on the same substrate as the thin film transistor by a manufacturing process similar to the thin film transistor. Is known (see, for example, Patent Document 1).

  FIG. 24 is a plan view showing the configuration of a conventional photosensor, and FIG. 25 is a cross-sectional view showing the configuration of the photosensor. The illustrated optical sensor 80 has the same structure as an n-channel MOS transistor. In this optical sensor 80, a control electrode 82 is formed in a strip shape on the upper surface of the substrate 81, and a first insulating film 83 is laminated so as to cover the control electrode 82. The first insulating film 83 is made of a light transmissive insulating material. A semiconductor film 84 is formed on the upper surface of the first insulating film 83. The semiconductor film 84 is roughly divided into a photoactive layer 85 and a pair of electrode regions 86 and 87. The photoactive layer 85 generates an electron-hole pair that is a source of photocurrent when light enters the photoactive layer 85. The photoactive layer 85 is disposed in a region overlapping the control electrode 82 in plan view.

  The pair of electrode regions 86 and 87 are formed by introducing impurities into the semiconductor film 84 on both sides of the photoactive layer 85. Of the pair of electrode regions 86 and 87, one electrode region 86 is a source region, and the other electrode region 87 is a drain region. The source region 86 and the drain region 87 are formed in a rectangular shape with the same area. The source region 86 is divided into a low concentration region 86L into which an impurity is introduced at a relatively low concentration and a high concentration region 86H into which an impurity is introduced at a relatively high concentration. The low concentration region 86L is divided into the photoactive layer 85. Adjacent to. Similarly, the drain region 87 is divided into a low concentration region 87L into which impurities are introduced at a relatively low concentration and a high concentration region 87H into which impurities are introduced at a relatively high concentration. Adjacent to the active layer 85.

  A second insulating film 88 is laminated on the upper surface of the first insulating film 83 so as to cover the semiconductor film 84. The second insulating film 88 is made of a light transmissive insulating material. A plurality of contact holes 89 are formed in the second insulating film 88 so as to expose a part of the high concentration region 86H of the source region 86, and a part of the high concentration region 87H of the drain region 87 is exposed. A plurality of contact holes 90 are formed as described above. The source-side contact hole 89 is embedded with the wiring material of the first wiring 91, and the drain-side contact hole 90 is embedded with the wiring material of the first wiring 92. A planarizing film 93 is laminated on the upper surface of the second insulating film 88 so as to cover the wirings 91 and 92. The planarizing film 93 is made of a light transmissive insulating material.

  In the optical sensor 80 configured as described above, when light is incident on the photoactive layer 85 of the semiconductor film 84 through the planarizing film 93, the second insulating film 88, and the like, electron-hole pairs are generated in the photoactive layer 85. , A photocurrent is generated. This photocurrent is read out outside the sensor as a light reception signal of the photosensor.

JP 2007-18458 A

  In general, since the photocurrent generated by the photosensor 80 using the semiconductor film 84 is very weak, it is necessary to read the photocurrent with high efficiency in order to increase the sensitivity of the photosensor 80. In order to read out photocurrent with high efficiency, it is effective to reduce the parasitic capacitance inside the sensor. The parasitic capacitance inside the sensor is such that the control electrode 82 and the source region 86 (low-concentration region 86L) that face each other through the first insulating film 83 and the control electrode that faces the first insulating film 83 are opposed to each other. This is one of the components having a large facing area between the drain region 87 and the drain region 87 (low concentration region 87L). Therefore, in order to reduce the parasitic capacitance inside the sensor, the area of the semiconductor film 84 may be reduced. However, when the area of the semiconductor film 84 is reduced, the area of the photoactive layer 85 is also reduced, so that the photocurrent generated inside the sensor is reduced.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide an optical sensor capable of reducing the parasitic capacitance inside the sensor without reducing the photocurrent generated inside the sensor. There is to do.

The optical sensor according to the present invention is
A control electrode formed on the substrate;
A semiconductor film including a photoactive layer and a pair of electrode regions located on both sides of the control electrode, the semiconductor film including a photoactive layer, and a control electrode;
The photoactive layer is disposed in a region overlapping the control electrode;
Regarding at least one of the pair of electrode regions, the length of the electrode region overlapping the end side of the control electrode is shorter than the length of the photoactive layer in the direction along the end side of the control electrode. It is characterized by.

  In the photosensor according to the present invention, with respect to at least one of the pair of electrode regions located on both sides of the photoactive layer, the length of the electrode region that overlaps the end side of the control electrode is set to the end of the control electrode. By making it shorter than the length of the photoactive layer in the direction along the side, it is possible to reduce the facing area between the electrode region and the control electrode without reducing the region of the photoactive layer.

  According to the optical sensor of the present invention, the parasitic capacitance inside the sensor can be reduced without reducing the photocurrent generated inside the sensor. For this reason, it is possible to read out photocurrent from the photosensor with high efficiency.

  Hereinafter, specific embodiments of the present invention will be described in detail with reference to the drawings. It should be noted that the technical scope of the present invention is not limited to the embodiments described below, and various modifications and improvements have been made within the scope of deriving specific effects obtained by the constituent requirements of the invention and combinations thereof. Also includes form.

<Overall configuration of display device>
FIG. 1 is a block diagram showing the overall configuration of a display device according to the present invention. The display device 1 includes a display panel 2, a backlight 3, a display drive circuit 4, a light receiving drive circuit 5, an image processing unit 6, and an application program execution unit 7.

  The display device 1 is a liquid crystal display device (LCD (Liquid Crystal Display)) using a liquid crystal panel as the display panel 2. The display panel 2 has a display area 8 for displaying an image. In the display area 8 of the display panel 2, a plurality of pixels are arranged in a matrix over the entire surface. The display panel 2 displays an image such as a predetermined graphic or character based on display data while performing a line sequential operation. The display area 8 is provided with an optical sensor that detects an object that is in contact with or close to the display surface (screen) of the display panel 2. This optical sensor, for example, inputs coordinates in the display area 8 using a finger or a stylus pen, images an object near the display surface of the display panel 2, and further detects the brightness of the environment in which the display panel 2 is installed. Etc. are possible.

  The backlight 3 serves as a light source for displaying an image on the display panel 2. The backlight 3 has a configuration in which, for example, a plurality of light emitting diodes are arranged in a plane. The backlight 3 performs the on / off operation of the light emitting diode at high speed at a predetermined timing synchronized with the operation timing of the display panel 2.

  The display drive circuit 4 is a circuit that drives the display panel 2 (drives a line sequential operation) so that an image based on the display data is displayed on the display panel 2 (to perform a display operation).

  The light receiving drive circuit 5 is a circuit that drives the display panel 2 (drives line-sequential operation) so that light receiving data can be obtained on the display panel 2 (so as to detect contact or proximity of an object). The light receiving drive circuit 5 has a frame memory 9. The light reception data at each pixel is output to the image processing unit 11 after being stored in the frame memory 9 in units of frames, for example.

  The image processing unit 6 performs predetermined image processing (arithmetic processing) based on the light reception data output from the light reception drive circuit 5, and information (position coordinate data, object shape, Data related to size) is detected and acquired.

  The application program execution unit 7 executes processing according to predetermined application software based on the detection result by the image processing unit 6. For example, the display program includes the position coordinates of the object detected by the image processing unit 6. And those displayed on the display panel 2. Display data generated by the application program execution unit 7 is supplied to the display drive circuit 4.

<Circuit configuration of display area>
FIG. 2 is a diagram showing a circuit configuration in the display area of the display panel. As illustrated, the display area 8 is provided with a pixel portion 11 and a sensor portion 12. A plurality of pixel units 11 and sensor units 12 are provided in the display area 8. The plurality of pixel portions 11 are arranged in a matrix over the entire display region 8, and the plurality of sensor units 12 are also arranged in a matrix over the entire display region 8. Specifically, in the vertical scanning direction (vertical direction) of the display panel 2, for example, as shown in FIG. 3, the pixel units 11 and the sensor units 12 are arranged alternately. Regarding the arrangement of the sensor unit 12, the sensor unit 12 may be arranged in a 1: 1 relationship with the sub-pixels corresponding to each of the red (R), green (G), and blue (B) color components. The sensor unit 12 may be arranged in a 1: 1 relationship with the main pixel including a set of three sub-pixels, or one sensor unit 12 may be arranged for a plurality of main pixels. Moreover, you may provide the sensor part 12 only for a part (predetermined site | part) of the display area 8 instead of the whole display area 8. FIG.

  In the display area 8, the pixel unit 11 is disposed at each intersection of a plurality of scanning lines 11 a wired in the horizontal direction and a plurality of signal lines 11 b wired in the vertical direction. Each pixel unit 11 is provided with a thin film transistor (TFT) Tr serving as a pixel driving switching element, for example.

  The thin film transistor Tr has a gate connected to the scanning line 11a, one source / drain connected to the signal line 11b, and the other source / drain connected to the pixel electrode 11c. Each pixel unit 11 is provided with a common electrode 11d that applies a common potential Vcom to all the pixel units 11.

  Then, the thin film transistor Tr is turned on / off based on a drive signal supplied via the scanning line 11a, and a pixel voltage is applied to the pixel electrode 11c based on a display signal supplied from the signal line 11b in the on state. The liquid crystal layer is driven by the electric field between the pixel electrode 11c and the common electrode 11d.

  On the other hand, the sensor unit 12 includes an optical sensor 15. The optical sensor 15 is configured using, for example, the same layer (same process) as the thin film transistor Tr of the pixel unit 11. That is, if the pixel unit 11 is provided on, for example, a transparent glass substrate, the optical sensor 15 is provided together with the pixel unit 11 on the glass substrate. In that case, since the pixel portion 11 is configured using a thin film transistor, and the thin film transistor is provided in an array on the substrate, the substrate is also referred to as a TFT array substrate or a driving substrate. The display panel 2 is configured by enclosing and sandwiching a liquid crystal layer between a TFT array substrate and a counter substrate (for example, a color filter substrate on which a color filter layer is formed).

  The optical sensor 15 is supplied with a power supply voltage VDD. The optical sensor 15 is connected to a reset switching element 12a and a capacitor (storage capacitor) 12b. The optical sensor 15 generates a photocurrent corresponding to the amount of received light by generating an electron-hole pair upon incidence (irradiation) of light. This photocurrent is read out of the sensor as a light reception signal of the photosensor 15. The light reception signal (signal charge) of the optical sensor 15 is accumulated in the capacitor 12b. The switching element 12a resets the light reception signal accumulated in the capacitor 12b at a predetermined timing. The light reception signal accumulated in the capacitor 12b is supplied (read) to the light reception signal wiring 12e via the buffer amplifier 12d at the timing when the switching element 12c for reading is turned on, and is output to the outside. The on / off operation of the reset switching element 12a is controlled by a reset signal supplied by a reset control line 12f. The on / off operation of the read switching element 12c is controlled by a read signal supplied from the read control line 12g.

<First Embodiment>
FIG. 3 is a plan view showing the configuration of the photosensor according to the first embodiment of the present invention, and FIG. 4 is a cross-sectional view showing the configuration of the photosensor. The illustrated optical sensor 15 has the same structure as an n-channel MOS transistor. In the optical sensor 15, a control electrode 22 is formed in a strip shape on the upper surface of the substrate 21, and a first insulating film 23 is laminated so as to cover the control electrode 22. The board | substrate 21 is comprised using the board | substrate which has a light transmittance, specifically, a transparent glass substrate, for example. The control electrode 22 corresponds to the gate electrode of the MOS transistor. A predetermined voltage is applied to the control electrode 22 via a control wiring (not shown) in order to control driving of the optical sensor 15. The control electrode 22 is configured using a light-reflective conductive material such as molybdenum or a refractory metal. The first insulating film 23 corresponds to the gate insulating film of the MOS transistor.

  The first insulating film 23 is made of a light transmissive insulating material (for example, silicon oxide, silicon nitride, etc.). A CVD (chemical vapor deposition) method can be used to form the first insulating film 23. A semiconductor film 24 is formed on the upper surface of the first insulating film 23. The semiconductor film 24 is a thin film made of, for example, polycrystalline silicon, and is formed on the first insulating film 23 so as to straddle the control electrode 22 in the channel length direction (left-right direction in the figure) of the MOS transistor. The semiconductor film 24 is formed, for example, by depositing amorphous silicon on the first insulating film 23 and then irradiating an excimer laser to polycrystallize the silicon film. The semiconductor film 24 is roughly divided into a photoactive layer 25 and a pair of electrode regions 26 and 27.

  The photoactive layer 25 corresponds to the channel of the MOS transistor and has a photoelectric conversion function. The photoactive layer 25 generates an electron-hole pair that is a source of photocurrent when light enters the photoactive layer 25. The photoactive layer 25 has a rectangular shape along the wiring direction of the control electrode 22 in plan view. The photoactive layer 25 is disposed in a region overlapping with the control electrode 22. In the channel length direction (source-drain direction) of the MOS transistor, the dimension of the photoactive layer 25 is set smaller than the dimension of the control electrode 22, and in the channel width direction (direction orthogonal to the channel length direction) of the MOS transistor. In addition, the dimension of the photoactive layer 25 is set smaller than the dimension of the control electrode 22. For this reason, the photoactive layer 25 is disposed so as to be completely contained in the formation region of the control electrode 22.

The pair of electrode regions 26 and 27 are formed by introducing (implanting) impurities into the semiconductor film 24 on both sides of the photoactive layer 25 using, for example, an ion implantation apparatus, and both are N ⁺ regions. Yes. Of the pair of electrode regions 26 and 27, one electrode region 26 serves as a source region constituting a MOS transistor, and the other electrode region 27 serves as a drain region constituting a MOS transistor. When forming the source region 26 and the drain region 27 in the semiconductor film 24 made of a polycrystalline silicon film, for example, after forming a silicon oxide film so as to cover the polycrystalline silicon film, the photolithography technique is used to form the silicon oxide film on the silicon oxide film. A resist is patterned. Next, the source region 26 and the drain region 27 are formed by introducing impurities into the polycrystalline silicon film from the opening of the resist using an ion implantation apparatus. Thereafter, the substrate 21 is put into an annealing furnace to activate the impurities. Next, after removing the resist, a resist pattern is formed again, and the polycrystalline silicon film and the silicon oxide film are patterned by a dry etcher.

  The source region 26 is divided into a low concentration region 26L into which impurities are introduced at a relatively low concentration and a high concentration region 26H into which impurities are introduced at a relatively high concentration. The low concentration region 26L is in the channel length direction. Adjacent to the photoactive layer 25. The low concentration region 26L of the source region 26 is arranged in a state straddling one end side of the control electrode 22 in the channel length direction. Similarly, the drain region 27 is divided into a low concentration region 27L into which impurities are introduced at a relatively low concentration and a high concentration region 27H into which impurities are introduced at a relatively high concentration. Adjacent to the photoactive layer 25 in the long direction. The low concentration region 27L of the drain region 27 is disposed in a state straddling the other end of the control electrode 22 in the channel length direction. Such a transistor structure is also called an LDD (Lightly Doped Drain) structure. The purpose of employing the LDD structure is to reduce the drain electric field. On the other hand, the high concentration region is provided in order to use both ends of the semiconductor film 24 as electrodes (source electrode, drain electrode). In this case, the end side of the control electrode 22 is a side that defines the end of the control electrode 2 in a pair of inter-electrode directions (source-drain direction) where one is the source region 26 and the other is the drain region 27.

  A second insulating film 28 is stacked on the upper surface of the first insulating film 23 so as to cover the semiconductor film 24. The second insulating film 28 is made of a light transmissive insulating material (for example, silicon oxide, silicon nitride, etc.). The second insulating film 28 can be formed by a chemical vapor deposition (CVD) method. In the second insulating film 28, one contact hole 29 is formed so as to expose a part of the high concentration region 26H of the source region 26, and a part of the high concentration region 27H of the drain region 27 is exposed. Thus, a plurality (five in the illustrated example) of contact holes 30 are formed. Each of the contact holes 29 and 30 is formed, for example, by forming a resist pattern on the second insulating film 28 by a photolithography technique and then etching the second insulating film 28 using the resist pattern. It is formed so as to penetrate the insulating film 28. The source side contact hole 29 is filled with the wiring material of the first wiring 31, and the drain side contact hole 30 is filled with the wiring material of the second wiring 32. For example, aluminum is used as the wiring material of the first wiring 31 and the second wiring 32. A planarizing film 33 is laminated on the upper surface of the second insulating film 28 so as to cover the wirings 31 and 32. The planarizing film 33 is made of a light transmissive organic insulating material.

  Here, when comparing the source region 26 and the drain region 27 of the semiconductor film 24, the drain region 27 is formed in a rectangular shape, whereas the source region 26 is formed in a trapezoid narrower than the drain region 27. More specifically, the longitudinal dimension of the rectangle defining the drain region 27 is the same as the length (longitudinal dimension) of the photoactive layer 25. On the other hand, the lower side of the trapezoid that defines the source region 26 has the same dimension as the length (longitudinal dimension) of the photoactive layer 25, but the upper side of the trapezoid that defines the source region 26 is the length of the photoactive layer 25. The dimensions are shorter than the dimensions. The length of the photoactive layer 25 described here refers to the length of the photoactive layer 25 in the direction along the edge of the control electrode 22 described above. In FIG. 3, since the photoactive layer 25 is formed in a vertically long band shape, the length of the photoactive layer 25 is defined by the longitudinal dimension of the photoactive layer 25. However, for example, when the photoactive layer 25 is formed in a horizontally long strip shape, the length of the photoactive layer 25 is defined by the short dimension of the photoactive layer 25.

  For this reason, with respect to the drain region 27, the length of the low concentration region 27L overlapping the end side of the control electrode 22 and the length of the photoactive layer 25 in the direction along the end side of the control electrode 22 (in this embodiment, the low concentration region 27L). And the length of the boundary between the photoactive layers 25) are the same length L1. On the other hand, for the source region 26, the length L2 of the low concentration region 26L overlapping the end side of the control electrode 22 is the length of the photoactive layer 25 in the direction along the end side of the control electrode 22 (in this embodiment, the low concentration region 26L and the length of the boundary between the photoactive layer 25) and L3 (L3 = L1). In the case of the illustrated example, the dimensional relationship is L3 × 0.65≈L2.

  In the optical sensor 15 configured as described above, when light enters the photoactive layer 25 of the semiconductor film 24 through the planarization film 33, the second insulating film 28, and the like, electron-hole pairs are generated in the photoactive layer 25. As a result, a photocurrent is generated. This photocurrent is read out outside the sensor as a light reception signal of the photosensor.

  Further, in the optical sensor 15 according to the first embodiment of the present invention, the length L2 of the low concentration region 26L overlapping the end side of the control electrode 22 is obtained by forming the source region 26 of the semiconductor film 24 in a trapezoidal shape. It is shorter than the length L3 of the photoactive layer 25 in the direction along the edge of the control electrode 22. For this reason, the opposing area of the control electrode 22 and the source region 26 (low concentration region 26L) is smaller than the opposing area of the control electrode 22 and the drain region 27 (low concentration region 27L). Therefore, as compared with the case where the source region 26 is formed in a rectangular shape like the drain region 27, the facing area between the control electrode 22 and the source region 26 is narrowed, and the parasitic capacitance inside the sensor is reduced accordingly. Further, since the longitudinal dimension of the photoactive layer 25 is maintained at the same dimension (L1 = L3) on both the source side and the drain side, the region (area) of the photoactive layer 25 serving as a source of electron-hole pairs is generated. ) Is maintained as it is. For this reason, the photocurrent generated inside the sensor does not decrease. As a result, the parasitic capacitance inside the sensor can be reduced without reducing the photocurrent generated inside the sensor. Therefore, it is possible to efficiently read out the photocurrent that becomes the light reception signal of the optical sensor 15.

  In the first embodiment, the drain region 27 has a rectangular shape and the source region 26 has a trapezoidal shape so that the facing area on the source side is smaller than the facing area on the drain side. On the contrary, the opposing area on the drain side may be made smaller than the opposing area on the source side by making the shape of the drain region 27 trapezoidal and the shape of the source region 26 rectangular.

Second Embodiment
FIG. 5 is a plan view showing a configuration of an optical sensor according to the second embodiment of the present invention. In the second embodiment, the shape of the drain region 27 is different from that in the first embodiment. That is, in the first embodiment, the shape of the drain region 27 is rectangular, but in the second embodiment, the shape of the drain region 27 is trapezoidal like the source region 26. For this reason, with respect to the drain region 27, the length L4 of the low concentration region 27L overlapping the end side of the control electrode 22 is shorter than the length L1 of the boundary portion between the low concentration region 27L and the photoactive layer 25. .

  In the optical sensor 15 configured as described above, both the source region 26 and the drain region 27 of the semiconductor film 24 are formed in a trapezoidal shape, thereby controlling the length L2 of the low concentration region 26L that overlaps the end side of the control electrode 22. The length of the photoactive layer 25 in the direction along the end side of the electrode 22 (in this embodiment, the length of the boundary portion between the low concentration region 26L and the photoactive layer 25) is set to be shorter than L3 and The length L4 (L4 = L2) of the overlapping low concentration region 27L is set to the length of the photoactive layer 25 in the direction along the edge of the control electrode 22 (in this embodiment, the boundary between the low concentration region 27L and the photoactive layer 25). Length) is shorter than L1. For this reason, compared with the first embodiment, the facing area between the control electrode 22 and the drain region 27 (low concentration region 27L) is narrowed, and the parasitic capacitance inside the sensor is reduced accordingly. Further, since the longitudinal dimension of the photoactive layer 25 is maintained at the same dimension (L1 = L3) on both the source side and the drain side, the region (area) of the photoactive layer 25 serving as a source of electron-hole pairs is generated. ) Is also maintained. For this reason, the photocurrent generated inside the sensor does not decrease. As a result, the parasitic capacitance inside the sensor can be further reduced without reducing the photocurrent generated inside the sensor. Therefore, it is possible to more efficiently and efficiently read out the photocurrent that becomes the light reception signal of the optical sensor 15.

<Third Embodiment>
FIG. 6 is a plan view showing a configuration of an optical sensor according to the third embodiment of the present invention. In the third embodiment, the shape of the source region 26 is different from that in the first embodiment. That is, in the first embodiment, the drain region 27 has a rectangular shape and the source region 26 has a trapezoidal shape. However, in the third embodiment, the drain region 27 has a rectangular shape, and the source region 26 has a rectangular shape. The shape is a comb-teeth shape. For this reason, with respect to the drain region 27, as in the first embodiment, the length of the low concentration region 27L that overlaps the edge of the control electrode 22 and the length of the boundary between the low concentration region 27L and the photoactive layer 25 However, the length L5 (L5 = L5a + L5b + L5c) of the low-concentration region 26L overlapping the end side of the control electrode 22 is at the end side of the control electrode 22 with respect to the source region 26. The length of the photoactive layer 25 along the direction is shorter than the length L3 (the length of the boundary between the low concentration region 26L and the photoactive layer 25 in this embodiment) L3.

  With this configuration, the facing area between the control electrode 22 and the source region 26 (low concentration region 26L) is narrower than the facing area between the control electrode 22 and the drain region 27 (low concentration region 27L). Therefore, as compared with the case where the source region 26 is formed in a rectangular shape like the drain region 27, the facing area between the control electrode 22 and the source region 26 is narrowed, and the parasitic capacitance inside the sensor is reduced accordingly. Further, since the longitudinal dimension of the photoactive layer 25 is maintained at the same dimension (L1 = L3) on both the source side and the drain side, the region (area) of the photoactive layer 25 serving as a source of electron-hole pairs is generated. ) Is also maintained. For this reason, the photocurrent generated inside the sensor does not decrease. As a result, the parasitic capacitance inside the sensor can be reduced without reducing the photocurrent generated inside the sensor. Therefore, it is possible to efficiently read out the photocurrent that becomes the light reception signal of the optical sensor 15.

  In the third embodiment, the drain area 27 has a rectangular shape, and the source area 26 has a comb shape so that the facing area on the source side is smaller than the facing area on the drain side. On the contrary, the opposing area on the drain side may be made smaller than the opposing area on the source side by making the drain region 27 into a comb shape and the source region 26 into a rectangle. Further, both the source region 26 and the drain region 27 may be formed in a comb shape.

<Fourth embodiment>
FIG. 7 is a plan view showing the configuration of the photosensor according to the fourth embodiment of the present invention, and FIG. 8 is a cross-sectional view showing the configuration of the photosensor. In the fourth embodiment, components having the same functions as those described in the first to third embodiments will be described with the same reference numerals. In the illustrated optical sensor 15, the control electrode 22, the source region 26 of the semiconductor film 24, the photoactive layer 25, and the drain region 27 are arranged concentrically. The control electrode 22 is formed in a donut shape. A control wiring 20 is connected to the control electrode 22. The semiconductor film 24 is formed in a circular shape (perfect circle). The semiconductor film 24 has a configuration in which a source region 26, a photoactive layer 25, and a drain region 27 are sequentially arranged in the radial direction (radiation direction) from the center of the optical sensor 15. Therefore, the photoactive layer 25 is formed in a donut shape on the outside so as to surround the circular source region 26, and the drain region 27 is formed in a donut shape on the outside so as to surround the photoactive layer 25. .

  The photoactive layer 25 is disposed in a region overlapping with the control electrode 22. The inner diameter of the photoactive layer 25 is set larger than the inner diameter of the control electrode 22, and the outer diameter of the photoactive layer 25 is set smaller than the outer diameter of the control electrode 22. For this reason, the photoactive layer 25 is disposed so as to be completely contained in the formation region of the control electrode 22.

  The source region 26 is divided into a high concentration region 26H on the inner side and a low concentration region 26L on the outer side, and the outer peripheral portion of the low concentration region 26L is adjacent to the inner peripheral portion of the photoactive layer 25. A contact hole 29 is provided at the center position of the high concentration region 26 </ b> H of the source region 26. The contact hole 29 is formed so as to penetrate the second insulating film 28 and is filled with the wiring material of the first wiring 31. Immediately below the first wiring 31, the control electrode 22 and the semiconductor film 24 are cut out except for the source region 26 in order to prevent the photoactive layer 25 corresponding to the channel of the MOS transistor from being coupled by the source signal. May be.

  The drain region 27 is divided into a high concentration region 27H on the outside and a low concentration region 27L on the inside, and the inner peripheral portion of the low concentration region 27L is adjacent to the outer peripheral portion of the photoactive layer 25. A part of the high concentration region 27H of the drain region 27 protrudes outward, and a contact hole 30 is formed in this protruding portion. The contact hole 30 is formed so as to penetrate the second insulating film 28 and is filled with the wiring material of the second wiring 32.

  Here, when comparing the source region 26 and the drain region 27 of the semiconductor film 24, the drain region 27 is formed in a donut shape outside the photoactive layer 25, whereas the source region 26 is formed of the photoactive layer 25. It is formed in a circle inside. Therefore, with respect to the drain region 27, the length (circumferential length) of the low concentration region 27 </ b> L overlapping the end side (outer peripheral edge) of the control electrode 22 is in the direction along the end side (circumferential direction) of the control electrode 22. It is longer than the length of the photoactive layer 25 (in this embodiment, the length (circumferential length) of the boundary between the low concentration region 27L and the photoactive layer 25). On the other hand, with respect to the source region 26, the length (circumferential length) of the low concentration region 26L overlapping the end side (inner peripheral edge) of the control electrode 22 is the direction along the end side of the control electrode 22 (circumferential direction). ) Of the photoactive layer 25 (in this embodiment, the length (circumferential length) of the boundary between the low concentration region 26L and the photoactive layer 25). For this reason, the opposing area of the control electrode 22 and the source region 26 (low concentration region 26L) is smaller than the opposing area of the control electrode 22 and the drain region 27 (low concentration region 27L). Therefore, assuming that the opposing area of the control electrode 22 and the drain region 27 is the same area as in the conventional structure (when the drain region is formed in a rectangular shape), the control electrode 22 The opposing area of the source region 26 is narrowed, and the parasitic capacitance inside the sensor is reduced accordingly.

  In general, in an optical sensor having a MOS transistor structure, an end of the photoactive layer on the source region side is defined as a “source end”, and an end of the photoactive layer on the drain region side is defined as a “drain end”. The contribution of generation is higher at the drain end than at the source end. This is because electron-hole pairs that generate a photocurrent are generated mainly at the drain end when light enters the photoactive layer. In the photosensor 15 according to the fourth embodiment, the semiconductor film 24 is arranged in such a manner that the source region 26 is arranged on the inner side and the drain region 27 is arranged on the outer side. It is possible to ensure a long circumferential length at the end. Therefore, more photocurrent can be generated as compared with the case where the source region 26 is disposed outside and the drain region 27 is disposed inside. As a result, the parasitic capacitance inside the sensor can be reduced without reducing the photocurrent generated inside the sensor. Therefore, it is possible to efficiently read out the photocurrent that becomes the light reception signal of the optical sensor 15. Further, the area of the element can be reduced as compared with an element having the same sensor efficiency.

  In the fourth embodiment, the shapes of the control electrode 22 and the semiconductor film 24 (inner peripheral shape, outer peripheral shape, etc.) are circular. However, the shape is not limited to this. Good.

  In the first to fourth embodiments, the optical sensor having an n-channel MOS transistor structure has been described as an example. However, the present invention is not limited to this, and the optical sensor having a p-channel MOS transistor structure. It is also applicable to.

  The present invention is not limited to a photosensor having a MOS transistor structure, but can be applied to a photosensor having a PIN diode structure. The PIN diode is configured using a semiconductor film divided into a p-type electrode region, an i-type photoactive layer, and an n-type electrode region. In that case, the pair of electrode regions located on both sides of the photoactive layer is constituted by an anode region and a cathode region that constitute a PIN diode. A specific embodiment when applied to an optical sensor having a PIN diode structure will be described below.

<Fifth Embodiment>
FIG. 9 is a plan view showing the configuration of the photosensor according to the fifth embodiment of the present invention, and FIG. 10 is a cross-sectional view showing the configuration of the photosensor. The illustrated optical sensor 45 has the same structure as a PIN type diode. In the optical sensor 45, a control electrode 47 is formed in a strip shape on the upper surface of the substrate 46, and a first insulating film 48 is laminated so as to cover the control electrode 47. The board | substrate 46 is comprised using the board | substrate which has a light transmittance, specifically, a transparent glass substrate, for example. The control electrode 47 is formed on the common substrate 46 in the same process as the gate electrode of the thin film transistor Tr (see FIG. 2) serving as a pixel driving switching element. A predetermined voltage is applied to the control electrode 47 via a control wiring (not shown) in order to control driving of the optical sensor 45. The control electrode 47 is configured using a light-reflective conductive material such as molybdenum or a refractory metal. The first insulating film 48 is formed in the same process as the gate insulating film of the thin film transistor Tr.

  The first insulating film 48 is made of a light transmissive insulating material (for example, silicon oxide, silicon nitride, etc.). For the formation of the first insulating film 48, a chemical vapor deposition (CVD) method can be used. A semiconductor film 49 is formed on the upper surface of the first insulating film 48. The semiconductor film 49 is a thin film made of, for example, polycrystalline silicon, and is formed on the first insulating film 48 so as to straddle the control electrode 47 in the left-right direction in the figure. The semiconductor film 49 is formed, for example, by depositing amorphous silicon on the first insulating film 48 and then irradiating an excimer laser to polycrystallize the silicon film. The semiconductor film 49 constitutes a PIN diode and is divided into a photoactive layer 50 and a pair of electrode regions 51 and 52. The photoactive layer 50 is I-type having a relatively low impurity concentration, and the pair of electrode regions 51 and 52 are P-type and N-type having relatively high impurity concentrations, respectively.

  The photoactive layer 50 has a photoelectric conversion function, and generates an electron-hole pair that is a source of photocurrent when light enters the photoactive layer 50. The photoactive layer 50 has a rectangular shape along the wiring direction of the control electrode 47 in plan view. The photoactive layer 50 is disposed in a region overlapping the control electrode 47. In the left-right direction of the figure, the dimension of the photoactive layer 50 is set smaller than the dimension of the control electrode 47, and in the vertical direction of the figure, the dimension of the photoactive layer 50 is set smaller than the dimension of the control electrode 47. Yes. For this reason, the photoactive layer 50 is disposed so as to be completely within the formation region of the control electrode 47.

A pair of electrode regions 51 and 52, intended to be formed by both sides introducing different impurities of conductivity type using the semiconductor film 49, for example, ion implantation apparatus in the photoactive layer 50 (injection), one P ⁺ The region is the N ⁺ region on the other side. Of the pair of electrode regions 51 and 52, one electrode region (P ⁺ region) 51 is an anode region, and the other electrode region (N ⁺ region) 52 is a cathode region. The anode region 51 is disposed so as to straddle one end side of the control electrode 47 in the left-right direction of the figure, and the cathode region 52 is disposed so as to straddle the other end side of the control electrode 47 in the left-right direction of the figure. Yes.

  A second insulating film 53 is laminated on the upper surface of the first insulating film 48 so as to cover the semiconductor film 49. The second insulating film 53 is made of a light transmissive insulating material (for example, silicon oxide, silicon nitride, etc.). For the formation of the second insulating film 53, a chemical vapor deposition (CVD) method can be used. One contact hole 54 is formed in the second insulating film 53 so as to expose a part of the anode region 51, and one contact hole 55 is formed so as to expose a part of the cathode region 52. ing. Each of the contact holes 54 and 55 is formed, for example, by forming a resist pattern on the second insulating film 53 by a photolithography technique and then etching the second insulating film 53 using the resist pattern. It is formed so as to penetrate the insulating film 53. The anode-side contact hole 54 is filled with the wiring material of the first wiring 56, and the cathode-side contact hole 55 is filled with the wiring material of the second wiring 57. As a wiring material for the first wiring 56 and the second wiring 57, for example, aluminum is used. A planarizing film 58 is laminated on the upper surface of the second insulating film 53 so as to cover the wirings 56 and 57. The planarizing film 58 is made of a light transmissive organic insulating material.

  Here, both the anode region 51 and the cathode region 52 of the semiconductor film 49 are formed in a T shape in plan view. For the anode region 51, the length L5 of the anode region 51 that overlaps the end side of the control electrode 47 is equal to the length of the photoactive layer 50 in the direction along the end side of the control electrode 47 (in this embodiment, The length of the boundary portion of the photoactive layer 50 is shorter than L6. Similarly, for the cathode region 52, the length L7 of the cathode region 52 that overlaps the end side of the control electrode 47 is equal to the length of the photoactive layer 50 in the direction along the end side of the control electrode 47 (in this embodiment, the cathode region 52). And the length of the boundary between the photoactive layer 50) and L8 (L8 = L6).

  In the optical sensor 45 configured as described above, when light enters the photoactive layer 50 of the semiconductor film 49 through the planarization film 58, the second insulating film 53, and the like, electron-hole pairs are generated in the photoactive layer 50. As a result, a photocurrent is generated. This photocurrent is read out outside the sensor as a light reception signal of the photosensor.

  Further, in the optical sensor 45 according to the fifth embodiment of the present invention, the anode region 51 and the cathode region 52 of the semiconductor film 49 are both formed in a T shape, so that the edge of the control electrode 47 is related to the anode region 51. Is longer than the length L5 of the photoactive layer 50 in the direction along the edge of the control electrode 47 (in this embodiment, the length of the boundary between the anode region 51 and the photoactive layer 50) L6. For the cathode region 52, the length L7 of the cathode region 52 that overlaps the end side of the control electrode 47 is set to the length of the photoactive layer 50 in the direction along the end side of the control electrode 47 (in this embodiment, the cathode region 52). And the length of the boundary between the photoactive layer 50) and L8. On the other hand, for example, as shown in FIG. 11, when both the anode region 51 and the cathode region 52 of the semiconductor film 49 are formed in a rectangular shape, the anode region 51 overlaps with the end side of the control electrode 47 with respect to the anode electrode 51. Is equal to the length L9 of the photoactive layer 50 in the direction along the edge of the control electrode 47 (the length of the boundary between the anode region 51 and the photoactive layer 50) L9. The length L10 (L9 = L10) of the cathode region 52 that overlaps the end side of the control electrode 47 is the length of the photoactive layer 50 in the direction along the end side of the control electrode 47 (the boundary between the cathode region 52 and the photoactive layer 50). Part length) L10.

  For this reason, the opposing area of the control electrode 47 and the anode region 51 is narrower than when the anode electrode 51 is formed in a rectangular shape, and the parasitic capacitance inside the sensor is reduced by that amount. Similarly, the facing area between the control electrode 47 and the cathode electrode 52 is narrower than that when the cathode electrode 52 is formed in a rectangular shape, and the parasitic capacitance inside the sensor is reduced accordingly. Further, in both the anode region 51 and the cathode region 52, the longitudinal dimension of the photoactive layer 50 is maintained at the same dimension (L6 = L8 = L9 = L10) as the sensor structure shown in FIG. The region (area) of the photoactive layer 50 serving as a pair generation source is maintained as it is. For this reason, the photocurrent generated inside the sensor does not decrease. As a result, the parasitic capacitance inside the sensor can be reduced without reducing the photocurrent generated inside the sensor. Therefore, it is possible to efficiently read out the photocurrent that becomes the light reception signal of the optical sensor 45.

<Sixth Embodiment>
FIG. 12 is a plan view showing a configuration of an optical sensor according to the sixth embodiment of the present invention. In the sixth embodiment, the shapes of the anode region 51 and the cathode region 52 are different from those of the fifth embodiment. That is, in the fifth embodiment, the anode region 51 and the cathode region 52 are both T-shaped. In the sixth embodiment, both the anode region 51 and the cathode region 52 are bowl-shaped. . Therefore, with respect to the anode region 51, the length L11 of the anode region 51 that overlaps the end side of the control electrode 47 is equal to the length of the photoactive layer 50 in the direction along the end side of the control electrode 47 (in this embodiment, the anode region 51). The length L13 (L13 = L11) of the cathode region 52 that overlaps the end side of the control electrode 47 is the control electrode 47. The length of the photoactive layer 50 in the direction along the edge of 47 (in this embodiment, the length of the boundary between the cathode region 52 and the photoactive layer 50) is shorter than L14 (L14 = L12).

  In the optical sensor 45 having the above-described configuration, the anode region 51 and the cathode region 52 of the semiconductor film 49 are both formed in a bowl shape, whereby the length L11 of the anode region 51 overlapping the end side of the control electrode 47 is set to the control electrode. The length of the photoactive layer 50 in the direction along the edge of 47 (in this embodiment, the length of the boundary between the anode region 51 and the photoactive layer 50) is shorter than L12, and the cathode overlaps with the edge of the control electrode 47 The length L13 of the region 52 is made shorter than the length L14 of the photoactive layer 50 in the direction along the edge of the control electrode 47 (in this embodiment, the length of the boundary between the cathode region 52 and the photoactive layer 50). Yes. For this reason, as shown in FIG. 11, the opposed area between the control electrode 47 and the anode region 51 is narrower than that in the case where both the anode region 51 and the cathode region 52 are formed in a rectangular shape. As the parasitic capacitance decreases, the opposing area between the control electrode 47 and the cathode region 52 becomes narrow, and the parasitic capacitance inside the sensor decreases accordingly. Further, on both the anode side and the cathode side, the longitudinal dimension of the photoactive layer 50 is maintained at the same dimension (L9 = L10 = L12 = L14) as the sensor structure shown in FIG. The region (area) of the photoactive layer 50 serving as a generation source is maintained as it is. For this reason, the photocurrent generated inside the sensor does not decrease. As a result, the parasitic capacitance inside the sensor can be further reduced without reducing the photocurrent generated inside the sensor. Accordingly, it is possible to efficiently and efficiently read out the photocurrent that becomes the light reception signal of the optical sensor 45.

<Seventh embodiment>
FIG. 13 is a plan view showing the configuration of the photosensor according to the seventh embodiment of the present invention, and FIG. 14 is a cross-sectional view showing the configuration of the photosensor. In the seventh embodiment, components having the same functions as those described in the fifth and sixth embodiments will be described with the same reference numerals. In the illustrated optical sensor 45, the control electrode 47, the anode electrode 51 of the semiconductor film 49, the photoactive layer 50, and the cathode region 52 are arranged concentrically. The control electrode 47 is formed in a donut shape. A control wiring 59 is connected to the control electrode 47. The semiconductor film 49 is formed in a circular shape (perfect circle). The semiconductor film 49 has a configuration in which a cathode region 52, a photoactive layer 50, and an anode region 51 are sequentially arranged from the center of the optical sensor 45 in the radial direction (radiation direction). For this reason, the photoactive layer 50 is formed in a donut shape on the outer side so as to surround the circular cathode region 52, and the anode region 51 is formed in a donut shape on the outer side so as to surround the photoactive layer 50. .

  The photoactive layer 50 is disposed in a region overlapping the control electrode 47. The inner diameter of the photoactive layer 50 is set larger than the inner diameter of the control electrode 47, and the outer diameter of the photoactive layer 50 is set smaller than the outer diameter of the control electrode 47. For this reason, the photoactive layer 50 is disposed so as to be completely within the formation region of the control electrode 47.

  The inner peripheral portion of the anode region 51 is adjacent to the outer peripheral portion of the photoactive layer 50. A part of the anode region 51 protrudes outward, and a contact hole 54 is formed in this protruding portion. The contact hole 54 is formed so as to penetrate the second insulating film 53 and is filled with a wiring material of the first wiring (anode wiring) 56.

  The outer periphery of the cathode region 52 is adjacent to the inner periphery of the photoactive layer 50. A contact hole 55 is provided at the center position of the cathode region 51. The contact hole 55 is formed so as to penetrate the second insulating film 53, and is filled with the wiring material of the second wiring (cathode wiring) 57.

  Here, when comparing the anode region 51 and the cathode region 52 of the semiconductor film 49, the anode region 51 is formed in a donut shape outside the photoactive layer 50, whereas the cathode region 52 is formed of the photoactive layer 50. It is formed in a circle inside. Therefore, with respect to the anode region 51, the length (circumferential length) of the anode region 51 that overlaps the end side (outer peripheral edge) of the control electrode 47 is the length of the photoactive layer 50 in the direction along the end side of the control electrode 47. (In this embodiment, the length (circumferential length) of the boundary between the anode region 51 and the photoactive layer 50) is longer. On the other hand, with respect to the cathode region 52, the length (circumferential length) of the cathode region 52 that overlaps the end side (inner peripheral edge) of the control electrode 47 is in the direction along the end side of the control electrode 47. (In this embodiment, the length (circumferential length) of the boundary between the cathode region 52 and the photoactive layer 50) is shorter. Therefore, the facing area between the control electrode 47 and the cathode region 52 is narrower than the facing area between the control electrode 47 and the anode region 51. Therefore, assuming that the opposing area of the control electrode 47 and the anode electrode 51 is the same as that when the anode electrode 51 and the cathode electrode 52 are both formed in a rectangular shape as shown in FIG. Compared with the sensor structure shown, the opposing area of the control electrode 47 and the cathode electrode 52 is narrowed, and the parasitic capacitance inside the sensor is reduced accordingly.

  In general, in an optical sensor having a PIN diode structure, an end of the photoactive layer on the anode region side is referred to as an “anode end”, and an end of the photoactive layer on the cathode region side is referred to as a “cathode end”. The contribution of generation is higher at the anode end than at the cathode end. This is because electron-hole pairs that generate a photocurrent are generated mainly at the anode end when light enters the photoactive layer. In the photosensor 45 according to the seventh embodiment, as the arrangement form of the semiconductor film 49, the cathode region 52 is arranged on the inner side and the anode region 51 is arranged on the outer side. It is possible to ensure a long circumferential length at the end. For this reason, more photocurrent can be generated compared with the case where the cathode region 52 is disposed outside and the anode region 51 is disposed inside. As a result, the parasitic capacitance inside the sensor can be reduced without reducing the photocurrent generated inside the sensor. Therefore, it is possible to efficiently read out the photocurrent that becomes the light reception signal of the optical sensor 45. Further, since the cathode region 52 is surrounded by the photoactive layer 50 and the anode region 51, it is possible to prevent the bias of the electric field distribution of the photoactive layer 50 and to compare with an element having the same sensor efficiency. The area of the element can be reduced.

  In the seventh embodiment, the shape of the control electrode 47 and the semiconductor film 49 (inner peripheral shape, outer peripheral shape, etc.) is circular. However, the present invention is not limited to this. For example, it may be a hexagon or a polygon larger than that. Good.

<Eighth Embodiment>
FIG. 15 is a plan view showing a configuration of an optical sensor according to the eighth embodiment of the present invention. In the eighth embodiment, the shapes of the photoactive layer 50 and the anode region 51 are different from those of the fifth embodiment. That is, in the fifth embodiment, the photoactive layer 50 is strip-shaped and the anode electrode 51 is T-shaped. In the eighth embodiment, a part of the photoactive layer 50 has the same width as the anode electrode 51. Thus, the anode electrode 51 is formed in an I-shape and the cathode electrode 52 is formed in a T-shape. For this reason, regarding the anode region 51, the length L 5 of the anode region 51 that overlaps the end side of the control electrode 47 is shorter than the length L 6 of the photoactive layer 50 in the direction along the end side of the control electrode 47. Regarding the cathode region 52, the length L 7 of the cathode region 52 that overlaps the end side of the control electrode 47 is shorter than the length L 8 of the photoactive layer 50 in the direction along the end side of the control electrode 47. Therefore, the same effect as that of the fifth embodiment can be obtained. Furthermore, compared with the fifth embodiment, the facing area between the control electrode 47 and the anode electrode 51 is narrowed, and the parasitic capacitance inside the sensor is reduced accordingly. The configuration employed in the eighth embodiment can be similarly applied to the above-described optical sensor having an n-channel MOS transistor structure. In this case, the anode electrode 51 portion becomes the source region portion, and the cathode electrode 52 portion becomes the drain region portion. As a modification of the eighth embodiment, the anode electrode 51 may be T-shaped and the cathode electrode 52 may be I-shaped.

<Ninth Embodiment>
FIG. 16 is a plan view showing a configuration of an optical sensor according to the ninth embodiment of the present invention. In the ninth embodiment, the shapes of the photoactive layer 50 and the cathode region 52 are different from those in the eighth embodiment. That is, in the ninth embodiment, a part of the photoactive layer 50 is projected to the cathode electrode 52 side with the same width as the cathode electrode 52, and the cathode electrode 52 is formed in an I shape in a continuous manner from the projected portion. is doing. Therefore, with respect to the cathode electrode 52, the length L5 of the anode region 51 that overlaps the end side of the control electrode 47 is shorter than the length L6 of the photoactive layer 50 in the direction along the end side of the control electrode 47. Regarding the cathode region 52, the length L 7 of the cathode region 52 that overlaps the end side of the control electrode 47 is shorter than the length L 8 of the photoactive layer 50 in the direction along the end side of the control electrode 47. Therefore, the same effects as those in the eighth embodiment can be obtained. Further, as compared with the fifth and eighth embodiments, the facing area of the control electrode 47 and the cathode electrode 52 is narrowed, and the parasitic capacitance inside the sensor is reduced accordingly. The configuration employed in the ninth embodiment can be similarly applied to the above-described optical sensor having an n-channel MOS transistor structure. In this case, the anode electrode 51 portion becomes the source region portion, and the cathode electrode 52 portion becomes the drain region portion.

<Tenth Embodiment>
FIG. 17 is a plan view showing the configuration of the photosensor according to the tenth embodiment of the present invention. In the ninth embodiment, the shapes of the anode electrode 51 and the cathode electrode 52 are different from those of the PIN type diode structure shown in FIG. That is, in the optical sensor 45 having the PIN diode structure shown in FIG. 11, the anode region 51 and the cathode region 52 of the semiconductor film 49 are both formed in a rectangular shape. However, in the tenth embodiment, the anode electrode 51 is used. A notch 60 is formed in a portion overlapping the control electrode 47, and a notch 60 is formed in a portion overlapping the control electrode 47 of the cathode electrode 52. The notch 60 is formed in a state where the width of the anode electrode 51 in the direction along the end side of the control electrode 47 (vertical direction in the drawing) is partially narrowed. Similarly, the notch 60 is the end side of the control electrode 47. The width of the cathode electrode 52 in the direction along the direction (vertical direction in the figure) is partially narrowed.

  In the optical sensor 45 having the above-described configuration, the notch 60 is provided in the cathode electrode 51, thereby reducing the facing area between the cathode electrode 51 and the control electrode 47, while providing the notch 60 in the anode electrode 52. The opposing area between the cathode electrode 52 and the control electrode 47 is reduced. Therefore, the parasitic capacitance inside the sensor is reduced as compared with the optical sensor 45 having the PIN diode structure shown in FIG. Moreover, since the longitudinal dimension of the photoactive layer 50 is maintained at the same dimension (L9 = L10 = L12 = L14) as the sensor structure shown in FIG. 11 on both the anode side and the cathode side, generation of electron-hole pairs The region (area) of the photoactive layer 50 serving as a source is maintained as it is. For this reason, the photocurrent generated inside the sensor does not decrease. As a result, the parasitic capacitance inside the sensor can be further reduced without reducing the photocurrent generated inside the sensor. Accordingly, it is possible to efficiently and efficiently read out the photocurrent that becomes the light reception signal of the optical sensor 45. Here, the cutouts 60, 60 are provided in both the anode electrode 51 and the cathode electrode 52, but cutouts may be provided in only one of them. Although not shown, at least one through hole having an arbitrary shape (for example, a circle, an ellipse, or a polygon) may be provided instead of the notch. Further, the configuration employed in the tenth embodiment can be similarly applied to the above-described optical sensor having an n-channel MOS transistor structure. In this case, the anode electrode 51 portion becomes the source region portion, and the cathode electrode 52 portion becomes the drain region portion.

<Eleventh embodiment>
FIG. 18 is a plan view showing a configuration of an optical sensor according to the eleventh embodiment of the present invention. In the eleventh embodiment, the arrangement relationship between the control electrode 47 and the semiconductor film 49 is different from the PIN type diode structure shown in FIG. That is, in the optical sensor 45 having the PIN diode structure shown in FIG. 9, the photoactive layer 50 and the cathode electrode 51 and the anode electrode 52 on both sides of the control electrode 47 are arranged so as to overlap each other. However, in the eleventh embodiment, only the photoactive layer 50 overlaps the control electrode 47 and the cathode electrode 51 and the anode electrode 52 do not overlap. Specifically, the dimensions (widths) of the control electrode 47 and the photoactive layer 50 are the same in the direction orthogonal to the direction along the edge of the control electrode 47 (the horizontal direction in the figure). The boundary between the photoactive layer 50 and the cathode electrode 51 is located on the same line as one end side of the control electrode 47, and the boundary between the photoactive layer 50 and the anode electrode 52 is the other end side of the control electrode 47. Located on the same line.

  In the optical sensor 45 having the above configuration, the facing area between the cathode electrode 51 and the control electrode 47 becomes substantially zero, and the facing area between the anode electrode 52 and the control electrode 47 becomes substantially zero. Therefore, the parasitic capacitance inside the sensor is reduced as compared with the optical sensor 45 having the PIN diode structure shown in FIG. Further, since the longitudinal dimension of the photoactive layer 50 is maintained at the same dimension as that of the sensor structure shown in FIG. 9, the region (area) of the photoactive layer 50 that is the source of electron-hole pairs is maintained as it is. . For this reason, the photocurrent generated inside the sensor does not decrease. As a result, the parasitic capacitance inside the sensor can be further reduced without reducing the photocurrent generated inside the sensor. The configuration employed in the eleventh embodiment can be similarly applied to the above-described optical sensor having an n-channel MOS transistor structure. In this case, the anode electrode 51 portion becomes the source region portion, and the cathode electrode 52 portion becomes the drain region portion.

<Application example>
The display device (liquid crystal display device) 1 according to the present invention is an electronic device such as various electronic devices shown in FIGS. 19 to 23, such as a digital camera, a notebook personal computer, a mobile terminal device such as a mobile phone, and a video camera. The present invention can be applied to electronic devices in various fields that display a video signal input to the video signal or a video signal generated in the electronic device as an image or video.

<First application example>
FIG. 19 is a perspective view showing a television as a first application example. The television according to this application example includes a video display screen unit 101 including a front panel 102, a filter glass 103, and the like, and the display device 1 described above can be applied to the video display screen unit 101.

<Second application example>
20A and 20B are diagrams showing a digital camera as a second application example, in which FIG. 20A is a perspective view seen from the front side, and FIG. 20B is a perspective view seen from the back side. The digital camera according to this application example includes a light emitting unit 111 for flash, a display unit 112, a menu switch 113, a shutter button 114, and the like, and the display device 1 can be applied to the display unit 112.

<Third application example>
FIG. 21 is a perspective view showing a notebook personal computer as a third application example. The notebook personal computer according to this application example includes a main body 121 including a keyboard 122 that is operated when inputting characters and the like, a display unit 123 that displays an image, and the like, and the display device 1 is applied to the display unit 123. Is possible.

<Fourth application example>
FIG. 22 is a perspective view showing a video camera as a fourth application example. The video camera according to this application example includes a main body 131, a lens 132 for shooting an object on a side facing forward, a start / stop switch 133 at the time of shooting, a display unit 134, and the like. The apparatus 1 can be applied.

<Fifth application example>
FIG. 23 is a diagram showing a mobile terminal device, for example, a mobile phone, as a fifth application example, in which (A) is a front view in an opened state, (B) is a side view thereof, and (C) is in a closed state. (D) is a left side view, (E) is a right side view, (F) is a top view, and (G) is a bottom view. The mobile phone according to this application example includes an upper housing 141, a lower housing 142, a connecting portion (here, a hinge portion) 143, a display 144, a sub display 145, a picture light 146, a camera 147, and the like. In addition, the display device 1 described above can be applied to the sub-display 145.

It is a block diagram which shows the whole structure of the display apparatus which concerns on this invention. It is a figure which shows the circuit structure in the display area of a display panel. It is a top view which shows the structure of the optical sensor which concerns on 1st Embodiment of this invention. It is sectional drawing which shows the structure of the optical sensor which concerns on 1st Embodiment of this invention. It is a top view which shows the structure of the optical sensor which concerns on 2nd Embodiment of this invention. It is a top view which shows the structure of the optical sensor which concerns on 3rd Embodiment of this invention. It is a top view which shows the structure of the optical sensor which concerns on 4th Embodiment of this invention. It is sectional drawing which shows the structure of the optical sensor which concerns on 4th Embodiment of this invention. It is a top view which shows the structure of the optical sensor which concerns on 5th Embodiment of this invention. It is sectional drawing which shows the structure of the optical sensor which concerns on 5th Embodiment of this invention. It is a figure which shows the comparative example with this invention. It is a top view which shows the structure of the optical sensor which concerns on 6th Embodiment of this invention. It is a top view which shows the structure of the optical sensor which concerns on 7th Embodiment of this invention. It is sectional drawing which shows the structure of the optical sensor which concerns on 7th Embodiment of this invention. It is a top view which shows the structure of the optical sensor which concerns on 8th Embodiment of this invention. It is a top view which shows the structure of the optical sensor which concerns on 9th Embodiment of this invention. It is a top view which shows the structure of the optical sensor which concerns on 10th Embodiment of this invention. It is a top view which shows the structure of the optical sensor which concerns on 11th Embodiment of this invention. It is a perspective view which shows the television used as the 1st application example. It is a figure which shows the digital camera used as the 2nd application example. It is a perspective view which shows the notebook personal computer used as the 3rd application example. It is a perspective view which shows the video camera used as the 4th application example. It is a figure which shows the portable terminal device used as the 5th application example. It is a top view which shows the structure of the conventional optical sensor. It is sectional drawing which shows the structure of the conventional optical sensor.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Display apparatus, 15 ... Optical sensor, 21 ... Substrate, 22 ... Control electrode, 23 ... 1st insulating film, 24 ... Semiconductor film, 25 ... Photoactive layer, 26 ... Source region (electrode region), 27 ... Drain Region (electrode region), 28 ... second insulating film, 29, 30 ... contact hole, 31 ... first wiring, 32 ... second wiring, 33 ... flattening film, 45 ... optical sensor, 46 ... substrate, 47 ... control electrode, 48 ... first insulating film, 49 ... semiconductor film, 50 ... photoactive layer, 51 ... anode region (electrode region), 52 ... cathode region (electrode region), 53 ... second insulating film, 54, 55 ... contact hole, 56 ... first wiring, 57 ... second wiring, 58 ... flattening film

Claims (8)

A control electrode formed on the substrate;
A semiconductor film including a photoactive layer and a pair of electrode regions located on both sides of the control electrode, the semiconductor film including a photoactive layer, and a control electrode;
The photoactive layer is disposed in a region overlapping the control electrode;
Regarding at least one of the pair of electrode regions, the length of the electrode region overlapping the end side of the control electrode is shorter than the length of the photoactive layer in the direction along the end side of the control electrode. An optical sensor characterized by The optical sensor according to claim 1, wherein the pair of electrode regions includes a source region and a drain region constituting a MOS transistor. The optical sensor according to claim 1, wherein the pair of electrode regions includes an anode region and a cathode region constituting a PIN diode. In a display device in which a pixel portion and an optical sensor are provided on a substrate,
The light sensor is
A control electrode formed on the substrate;
A semiconductor film including a photoactive layer and a pair of electrode regions located on both sides of the control electrode, the semiconductor film including a photoactive layer, and a control electrode;
The photoactive layer is disposed in a region overlapping the control electrode;
Regarding at least one of the pair of electrode regions, the length of the electrode region overlapping the end side of the control electrode is shorter than the length of the photoactive layer in the direction along the end side of the control electrode. A display device. A control electrode formed on the substrate;
A semiconductor film including a photoactive layer and a pair of electrode regions located on both sides of the control electrode, the semiconductor film including a photoactive layer, and a control electrode;
The photoactive layer is disposed in a region overlapping the control electrode;
An optical sensor, wherein at least one of the pair of electrode regions is formed with a notch or a through hole in a portion overlapping with the control electrode. In a display device in which a pixel portion and an optical sensor are provided on a substrate,
The light sensor is
A control electrode formed on the substrate;
A semiconductor film including a photoactive layer and a pair of electrode regions located on both sides of the control electrode, the semiconductor film including a photoactive layer, and a control electrode;
The photoactive layer is disposed in a region overlapping the control electrode;
A display device, wherein at least one of the pair of electrode regions is formed with a notch or a through hole in a portion overlapping with the control electrode. A control electrode formed on the substrate;
A semiconductor film including a photoactive layer formed to face the control electrode through an insulating film and a pair of electrode regions located on both sides thereof,
The boundary between the photoactive layer and the pair of electrode regions located on both sides thereof is located on the same line as the end side of the control electrode. In a display device in which a pixel portion and an optical sensor are provided on a substrate,
The light sensor is
A control electrode formed on the substrate;
A semiconductor film including a photoactive layer formed to face the control electrode through an insulating film and a pair of electrode regions located on both sides thereof,
A boundary between the photoactive layer and the pair of electrode regions located on both sides thereof is located on the same line as an end side of the control electrode.

Images