Two-dimension photosensor and method of manufacturing two-dimension photosensor

Abstract

To provide a two-dimension photosensor which can be manufactured at a low cost in a thin film transistor plant and covers a relatively wide two-dimension plane.SOLUTION: The two-dimensional photosensor 100 includes a plurality of photodiodes arranged, each photodiode including a stack of a first metal electrode 11, a first semiconductor layer 12, a first ohmic contact layer 13, and a first transparent electrode 16, the first semiconductor layer 12 and the first ohmic contact layer 13 being disposed between the first metal electrode 11 and the first transparent electrode 16, A Schottky barrier is provided on an interface between the first semiconductor layer 12 and the first metal electrode 11 or an interface between the first semiconductor layer 12 and the first transparent electrode 16, and light incident from the side of the first transparent electrode 16 toward the first semiconductor layer 12 is sensed.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present invention relates to a two-dimensional photosensor and a method for manufacturing the two-dimensional photosensor. [Background technology]

[0002] Two-dimensional photosensors have traditionally been used in imaging devices, fingerprint authentication devices, and the like. A two-dimensional photosensor has photodiodes that are sensitive to light. A plurality of photodiodes are arranged vertically and horizontally. The photodiodes are, for example, PIN-type semiconductor elements such as solar cells. The semiconductor layer is, for example, an amorphous silicon (hereinafter, a-Si) layer. An example of applying a two-dimensional photosensor to a fingerprint sensor is disclosed in Patent Document 1 listed below. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2017-194676 Summary of the Invention [Problem to be solved by the invention]

[0004] Patent Document 1 discloses an optical fingerprint sensor. Optical fingerprint sensors use reflected light to read high-resolution fingerprint patterns in a small area the size of a fingertip. The configuration used in fingerprint sensors is not suitable for detecting the distribution of ambient light over an area larger than the fingerprint area. For example, detecting the distribution of ambient light over the entire display surface is an example. Assume that the display is an organic light-emitting diode (OLED) display. OLED displays do not use the pin-in-type coupling used in fingerprint sensors. Applying the fingerprint sensor configuration to an organic EL display requires the addition of a semiconductor layer that forms a pin-in-type coupling, which is not an inherent component, over the entire display surface. However, it is difficult to uniformly arrange pin-in-type amorphous silicon (a-Si) photodiodes (PDs) over the large area of ​​a display. On the other hand, detecting the distribution of ambient light over a relatively large two-dimensional space such as a display does not require a high-density sensor arrangement like a fingerprint sensor.

[0005] When applying two-dimensional photosensors to devices with a relatively large area, such as displays, there is a greater need to keep costs down. PIN-type diodes are expensive, so factories capable of manufacturing PIN-type structures must be selected. They are not compatible with the manufacturing process of thin-film transistors, making process sharing difficult.

[0006] SUMMARY OF THE INVENTION An object of the present invention is to provide a two-dimensional photosensor that can be manufactured inexpensively in a thin film transistor factory and that can detect over a relatively wide two-dimensional plane. [Means for solving the problem]

[0007] The two-dimensional photosensor includes an array of photodiodes, each of which has a stack of a first metal electrode, a first semiconductor layer, a first ohmic contact layer, and a first transparent electrode, and the first semiconductor layer and the first ohmic contact layer are arranged between the first metal electrode and the first transparent electrode. The photodiode has a Schottky barrier at the interface between the first semiconductor layer and the first metal electrode or at the interface between the first semiconductor layer and the first transparent electrode, and senses light incident from the side of the first transparent electrode toward the first semiconductor layer.

[0008] In the two-dimensional photosensor, the first semiconductor layer is made of amorphous silicon, and the first ohmic contact layer is made of n+ amorphous silicon.

[0009] In the two-dimensional photosensor, the first metal electrode has a light-shielding property and is configured to be drawn out of the light-sensing region.

[0010] In a two-dimensional photosensor, the photocurrent of each photodiode is acquired individually through direct connection or scanned and acquired through a simple matrix method.

[0011] The two-dimensional photosensor includes a readout circuit that reads out a signal from the photodiode, and the readout circuit has a thin-film transistor, and the thin-film transistor has at least one layer that is the same as the layer that constitutes the photodiode.

[0012] In the two-dimensional photosensor, the thin-film transistor has a second metal electrode, which functions as a gate electrode of the thin-film transistor, and the second metal electrode is made of the same layer as the first metal electrode of the photodiode and is not electrically connected to each other.

[0013] In the two-dimensional photosensor, the thin film transistor has a source electrode and a drain electrode, and the source electrode and the drain electrode include at least the same layer as the first transparent electrode or the first metal electrode of the photodiode.

[0014] In the two-dimensional photosensor, the thin film transistor has a second semiconductor layer, and the second semiconductor layer is made of the same layer as the first semiconductor layer of the photodiode.

[0015] In the two-dimensional photosensor, the thin film transistor has a second semiconductor layer made of indium gallium zinc oxide.

[0016] In a two-dimensional photosensor, the photodiode has a dielectric layer on the outermost surface opposite the glass substrate to reduce surface reflection.

[0017] A method for manufacturing a two-dimensional photosensor, the two-dimensional photosensor comprising an array of photodiodes and a signal readout circuit from the photodiodes, the photodiodes comprising a stack of a first metal electrode, a first semiconductor layer, a first ohmic contact layer, and a first transparent electrode, the first semiconductor layer and the first ohmic contact layer being disposed between the first metal electrode and the first transparent electrode, a Schottky barrier being present at the interface between the first semiconductor layer and the first metal electrode or at the interface between the first semiconductor layer and the first transparent electrode, and sensing light incident from the first transparent electrode side toward the first semiconductor layer, the signal readout circuit comprising a thin film transistor, and the method comprising a step of simultaneously forming at least one layer constituting the photodiode and the thin film transistor.

[0018] A method for manufacturing a two-dimensional photosensor, wherein the thin film transistor has a gate electrode, a second semiconductor layer, a second ohmic contact layer, a source electrode, and a drain electrode, and the method includes at least one of a metal electrode formation process for simultaneously forming a first metal electrode and a gate electrode or a metal electrode formation process for simultaneously forming a first metal electrode and a source electrode and a drain electrode, a semiconductor layer formation process for simultaneously forming a first semiconductor layer and a second semiconductor layer, an ohmic contact layer formation process for simultaneously forming a first ohmic contact layer and a second ohmic contact layer, and a transparent electrode formation process for simultaneously forming a first transparent electrode and a source electrode and a drain electrode.

[0019] A method for manufacturing a two-dimensional photosensor, wherein the first semiconductor layer includes amorphous silicon and the first ohmic contact layer includes n+ amorphous silicon.

[0020] A method for manufacturing a two-dimensional photosensor, wherein the first semiconductor layer includes an amorphous silicon layer, the first ohmic contact layer includes an n+ amorphous silicon layer, and the thin-film transistor has a second metal electrode disposed on a glass substrate and functioning as a gate electrode, a second semiconductor layer consisting of an IGZO layer, and a second transparent electrode disposed on the second semiconductor layer and functioning as a source electrode and a drain electrode, and the method for manufacturing the two-dimensional photosensor includes a metal electrode formation process for simultaneously forming the first metal electrode and the second metal electrode, and a transparent electrode formation process for simultaneously forming the first transparent electrode and the second transparent electrode. [Effects of the Invention]

[0021] The present invention provides a two-dimensional photosensor capable of detecting grayscales over a relatively wide two-dimensional plane. [Brief explanation of the drawings]

[0022] [Figure 1] 1 is an overall circuit diagram of a two-dimensional photosensor according to a first embodiment of the present invention. [Figure 2]FIG. 3 is a diagram showing an example of the characteristics of the photodiode according to the first embodiment of the present invention. [Figure 3] 2 is a schematic diagram showing an output signal from a gate driver, an output signal from a signal processing circuit, and an input signal to the signal processing circuit according to the first embodiment of the present invention. FIG. [Figure 4] FIG. 1 is a plan view of a photosensing section according to a first embodiment of the present invention. [Figure 5] 1 is a cross-sectional view of a photodiode according to a first embodiment of the present invention. [Figure 6] FIG. 2 is a cross-sectional view of a photosensing section according to the first embodiment of the present invention. [Figure 7] 3 is a cross-sectional view of a manufacturing process of the photosensing unit according to the first embodiment of the present invention. FIG. [Figure 8] 3 is a cross-sectional view of a manufacturing process of the photosensing unit according to the first embodiment of the present invention. FIG. [Figure 9] 3 is a cross-sectional view of a manufacturing process of the photosensing unit according to the first embodiment of the present invention. FIG. [Figure 10] 3 is a cross-sectional view of a manufacturing process of the photosensing unit according to the first embodiment of the present invention. FIG. [Figure 11] 3 is a cross-sectional view of a manufacturing process of the photosensing unit according to the first embodiment of the present invention. FIG. [Figure 12] 3 is a cross-sectional view of a manufacturing process of the photosensing unit according to the first embodiment of the present invention. FIG. [Figure 13] 3 is a cross-sectional view of a manufacturing process of the photosensing unit according to the first embodiment of the present invention. FIG. [Figure 14] 3 is a cross-sectional view of a manufacturing process of the photosensing unit according to the first embodiment of the present invention. FIG. [Figure 15] FIG. 10 is a plan view of a photosensing section according to Modification 1 of the present invention. [Figure 16] FIG. 10 is a cross-sectional view of a photosensing section according to Modification 1 of the present invention. [Figure 17] FIG. 6 is a cross-sectional view of a photosensing section according to a second embodiment of the present invention. [Figure 18]FIG. 10 is a cross-sectional view of a photo-sensing unit according to a second embodiment of the present invention in one manufacturing step. [Figure 19] FIG. 10 is a cross-sectional view of a photo-sensing unit according to a second embodiment of the present invention in one manufacturing step. [Figure 20] FIG. 10 is a cross-sectional view of a photo-sensing unit according to a second embodiment of the present invention in one manufacturing step. [Figure 21] FIG. 10 is a cross-sectional view of a photo-sensing unit according to a second embodiment of the present invention in one manufacturing step. [Figure 22] FIG. 10 is a cross-sectional view of a photo-sensing unit according to a second embodiment of the present invention in one manufacturing step. [Figure 23] FIG. 10 is a cross-sectional view of a photo-sensing unit according to a second embodiment of the present invention in one manufacturing step. [Figure 24] FIG. 10 is a cross-sectional view of a photo-sensing unit according to a second embodiment of the present invention in one manufacturing step. [Figure 25] FIG. 10 is a cross-sectional view of a photodiode according to a second modified example of the present invention. [Figure 26] FIG. 10 is a plan view of a photodiode according to a third modified example of the present invention. [Figure 27] FIG. 10 is a cross-sectional view of a photodiode according to a third modified example of the present invention. [Figure 28] FIG. 10 is a cross-sectional view of a photodiode according to a fourth modified example of the present invention. [Figure 29] FIG. 10 is a schematic diagram showing the relationship between a photodiode and a signal processing circuit according to a fourth modified example of the present invention. [Figure 30] FIG. 10 is a cross-sectional view of a photodiode according to a fifth modified example of the present invention. [Figure 31] FIG. 10 is a cross-sectional view of a photodiode according to a sixth modified example of the present invention. [Figure 32] FIG. 11 is a cross-sectional view of a photodiode according to a seventh modification of the present invention. [Figure 33] FIG. 13 is an overall circuit diagram of a two-dimensional photosensor according to an eighth modified example of the present invention. [Figure 34] FIG. 13 is a plan view of a photosensing section according to an eighth modified example of the present invention. [Figure 35] FIG. 13 is a cross-sectional view of a photosensing section according to an eighth modified example of the present invention. [Figure 36] FIG. 13 is an overall circuit diagram of a two-dimensional photosensor according to a ninth modified example of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0023] A two-dimensional photosensor 100 according to a first embodiment of the present invention will be described below with reference to the drawings. In each drawing, the same components are given the same reference numerals. When the same components are to be distinguished as a first component, a second component, etc., a, b, etc. are added to the reference numeral.

[0024] (Embodiment 1) 1 is an overall circuit diagram of a two-dimensional photosensor 100 according to a first embodiment of the present invention. The two-dimensional photosensor 100 includes a photosensing section 200, a gate driver 130, scanning electrodes 2, signal readout electrodes 3, a multiplexer 140, and a signal processing circuit 150. The photosensing section 200 includes a photodiode 110 and a readout circuit 120.

[0025] The photodiode 110 receives external light L and outputs a current. The readout circuit 120 has a signal readout circuit thin-film transistor 121. The gate driver 130 has gate signal output terminals. The gate signal output terminals are connected to the plurality of scanning electrodes 2, respectively. The scanning electrodes 2 sequentially transmit signals from the gate driver 130 to the readout circuit 120. One end of the photodiode 110, which functions as an anode electrode, is connected to a reference voltage unit 4, and the other end, which functions as a cathode electrode, is connected to the readout circuit 120. The readout circuit 120 receives a signal from the gate driver 130 and reads out the photocurrent of the photodiode 110. The readout circuit 120 transmits the readout photocurrent of the photodiode 110 to a signal readout electrode 3. The signal readout electrode 3 transmits the transmitted photocurrent to a multiplexer 140. The multiplexer 140 sequentially transmits the signals from the plurality of signal readout electrodes 3 to a signal processing circuit 150. The signal processing circuit 150 processes as a signal the photocurrent output from the photodiode 110. If the photocurrent is large, the signal processing circuit 150 determines that light is being irradiated, and calculates the intensity of incident light based on the amount of photocurrent.

[0026] The gate driver 130 sequentially outputs voltages to the multiple scanning electrodes 2, i.e., scanning electrodes 2a, . . . , scanning electrode 2n, scanning electrode 2n+1, . . . In other words, the scanning electrodes 2 are scanned. The readout circuits 120 operate sequentially in conjunction with the scanning. Multiple readout circuits 120 are connected to each scanning electrode 2. For example, the readout circuit 120 connected to the scanning electrode 2a reads the photocurrent of the photodiode 110 when the scanning electrode 2a is scanned and transmits it to the signal processing circuit 150. Next, the readout circuit 120 connected to the scanning electrode 2n reads the photocurrent of the photodiode 110 when the scanning electrode 2n is scanned and transmits it to the signal processing circuit 150. As the scanning electrodes 2 are sequentially scanned, the photocurrents of the two-dimensionally arranged photodiodes 110 are sequentially transmitted to the signal processing circuit 150. Then, the photocurrents of the photodiodes 110 across the entire surface of the two-dimensional photosensor 100 are transmitted to the signal processing circuit 150. The signal from the signal processing circuit 150 is digitized by an analog-to-digital converter and connected to a central processing unit (not shown). The central processing unit calculates the two-dimensional distribution of the incident light intensity based on the information obtained from the signal processing circuit 150.

[0027] FIG. 2 is a diagram showing an example of the characteristics of the photodiode 110. The structure will be described in detail later, but the photodiode 110 according to this embodiment is a Schottky diode. The horizontal axis represents the voltage applied to the photodiode 110. The positive direction of the horizontal axis represents a state in which a voltage is applied to the photodiode 110 in the forward direction. The negative direction of the horizontal axis represents a state in which a voltage is applied to the photodiode 110 in the reverse direction. The vertical axis represents the photocurrent output by the photodiode 110, measured in amperes. The illuminance of the external light L irradiating the photodiode 110 was varied from 0 lux to 7006 lux. The experimental results for an illuminance of 0 lux represent the results of an experiment conducted in a darkroom.

[0028] Referring to the data in the darkroom, when a voltage is applied in the forward direction, the current increases. This indicates that a current flows from the photodiode 110. When a voltage is applied in the reverse direction, i.e., when a voltage is applied in the negative direction on the horizontal axis in Figure 2, only a minute current called a dark current flows until the voltage drops below -4V.

[0029] Next, let us look at the data when external light L is irradiated and the illuminance is changed from 1802 lux to 7006 lux. When a forward voltage is applied, the current increases. In other words, it shows that a current flows from the photodiode 110. This is similar to the data when the illuminance is 0 or in a dark room. When a voltage is applied in the reverse direction, that is, when a voltage is applied in the negative direction on the horizontal axis in Figure 2, a current flows, as shown in Figure 2. The higher the illuminance, the larger the current that flows. For example, when an applied voltage is minus 2V, when the illuminance is 0 lux, the dark current is very small, at almost 0 amperes, and when the illuminance is 1802 lux, the current is approximately 0.8 x 10 -9 Ampere, if the illuminance is 3672 lux, it is equivalent to 2 x 10 -9 Ampere, illuminance 7006 lux, equivalent to 3.9 x 10 -9 An ampere of photocurrent flows.

[0030] FIG. 3 is a schematic diagram showing the output signal and reset signal from the gate driver 130, and the output voltage of the signal processing circuit 150. The horizontal axis represents time. FIG. 3(a) shows the output voltage from the gate driver 130 to the scan electrode 2n in the nth row. FIG. 3(b) shows the output voltage from the gate driver 130 to the scan electrode 2n+1 in the (n+1)th row. FIG. 3(c) shows the reset state of the reset switch 152 of the signal processing circuit 150 in the mth column shown in FIG. 1. FIG. 3(d) shows the output voltage Vout of the signal processing circuit 150 based on the photodiode 110 in the mth column and nth row.

[0031] When the n-th row scan electrode 2 is scanned, an ON voltage (e.g., +15 V) is applied to the n-th row scan electrode 2 at time t1, as shown in FIG. 3(a). When an ON voltage is applied to the scan electrode 2 shown in FIG. 1, the gate of the signal readout circuit thin-film transistor 121 opens, and the source-drain electrode of the signal readout circuit thin-film transistor 121 becomes conductive. That is, the switch of the signal readout circuit thin-film transistor 121 becomes ON as a switch. At this time, an OFF voltage (e.g., −5 V) is applied to the n+1-th row scan electrode 2n+1, as shown in FIG. 3(b).

[0032] As shown in FIG. 1, the signal processing circuit 150 has an operational amplifier 151. The signal processing circuit 150 applies a reference voltage (see FIG. 1, Vref, for example, +1.5 V) to the signal readout electrode 3 via the operational amplifier 151. At time t1, as shown in FIG. 3(c), the reset switch 152 of the signal processing circuit 150 is turned on. Then, the operational amplifier 151 is reset. As shown in FIG. 3(d), the detection voltage of the signal processing circuit 150 decreases from time t1 to time t2. That is, the voltage based on the photodiode 110 is reset. The time between time t1 and time t2 is, for example, 160 microseconds. At time t2, as shown in FIG. 3(c), the reset switch 152 of the signal processing circuit 150 is turned off. At this time, the reference voltage is applied to the photodiode 110 as a reverse bias voltage. As shown in FIG. 3(a), an ON voltage is applied to the n-th row scanning electrode 2 until time t3. Then, a photocurrent flows in the photodiode 110 due to external light L, and the voltage of the signal readout electrode 3 attempts to decrease. Due to the operation of the operational amplifier 151 of the signal processing circuit 150, the output voltage (Vout) of the signal processing circuit 150 gradually increases from time t2 to time t3, as shown in FIG. 3(d). At time t3, an OFF voltage is applied to the scan electrode 2 of the nth row, as shown in FIG. 3(a). The output voltage (Vout) of the signal processing circuit 150 reaches a maximum at time t3, as shown in FIG. 3(d). The voltage at time t3 is detected by the signal processing circuit 150 as a voltage representing the intensity of light incident on the photodiode 110.

[0033] At time t4, an ON voltage is applied to the scan electrode 2 in the (n+1)th row. Similarly, the intensity of light incident on the photodiode 110 is detected for the (n+1)th row and beyond. The above scanning is performed from the first row to the last row, and after the last row, the scanning returns to the first row. Based on the photocurrent of the photodiode 110, the intensity of the incident light is detected from the first column to the last column of the first row, and further to the last column of the last row. That is, the intensity of the incident light is detected on a two-dimensional plane.

[0034] The operation of two-dimensional photosensor 100 has been described above as the operation of an electronic circuit. The structure of two-dimensional photosensor 100 according to this embodiment will now be described.

[0035] 4 is a plan view of the photosensing unit 200. The photosensing unit 200 has a photodiode 110 and a readout circuit 120. The readout circuit 120 has a signal readout circuit thin-film transistor 121. The photodiode 110 has a first metal electrode 11, a first semiconductor layer 12, and a first transparent electrode 16. The signal readout circuit thin-film transistor 121 has a first gate electrode 21a, a third insulating layer 24 (not shown in FIG. 4), a second semiconductor layer 22, a transparent source electrode 26a, and a transparent drain electrode 26b.

[0036] The first metal electrode 11 extends linearly in the left-right direction of the two-dimensional photosensor 100. The first metal electrode 11 is connected to the reference voltage unit 4 shown in FIG. 1 but not shown in FIG. 4. The first metal electrode 11 extends in a rectangular shape in the up-down direction in the photosensing unit 200. A first semiconductor layer 12 is formed in an island shape on the first metal electrode 11. A first ohmic contact layer 13 (not shown in FIG. 4) is formed in an island shape so as to cover the first semiconductor layer 12. A first insulating layer 14 (not shown in FIG. 4) is arranged so as to cover the glass substrate 1 and a portion of the first ohmic contact layer 13. A first transparent electrode 16 is arranged in a planar shape in contact with the first ohmic contact layer 13.

[0037] As shown in FIG. 1 , the scanning electrode 2 extends, for example, in the left-right direction of the two-dimensional photosensor 100 and the left-right direction of the photosensing section 200. In the photosensing section 200, the scanning electrode 2 has an extending portion within a two-dimensional plane. The signal readout circuit thin film transistor 121 has the extending portion of the scanning electrode 2 as a first gate electrode 21a. The signal readout circuit thin film transistor 121 has a planar third insulating layer 24 on the first gate electrode 21a. The signal readout circuit thin film transistor 121 has a second semiconductor layer 22 on the third insulating layer 24. The second semiconductor layer 22 is island-shaped. The signal readout circuit thin film transistor 121 may have an ohmic contact layer on the second semiconductor layer 22. The signal readout circuit thin film transistor 121 has a transparent source electrode 26a and a transparent drain electrode 26b. The signal readout electrode 3 has a branch-like extending portion. The extending portion of the signal readout electrode 3 is electrically connected to the transparent source electrode 26a of the signal readout circuit thin film transistor 121, forming the metal source electrode 3a. The same layer as the signal readout electrode 3 forms a rectangular island-shaped metal drain electrode 3b. The metal drain electrode 3b is electrically connected to the transparent drain electrode 26b. The transparent drain electrode 26b is electrically connected to the first transparent electrode 16 of the photodiode 110. When a predetermined voltage, for example, 15 V, is applied to the first gate electrode 21a, the transparent source electrode 26a and the transparent drain electrode 26b are electrically connected. The signal readout circuit thin film transistor 121 functions as a switch.

[0038] 5 is a cross-sectional view of the photodiode 110 taken along line II' in FIG. 4. The photodiode 110 is disposed on a glass substrate 1. The glass substrate 1 may be a film substrate. The photodiode 110 includes a stack of a first metal electrode 11, a first semiconductor layer 12, a first ohmic contact layer 13, a first insulating layer 14, and a first transparent electrode 16. Constituent layers that are omitted in FIG. 4 are shown in FIG. 5.

[0039] The glass substrate 1 is, for example, alkali-free glass, such as borosilicate glass. The glass substrate 1 has a thickness of, for example, 0.5 to 0.7 mm. A first metal electrode 11 is disposed on the glass substrate 1. The first metal electrode 11 has a substantially rectangular shape, for example, as shown in FIG. 4. The first metal electrode 11 is, for example, an alloy of molybdenum and tantalum. Other examples include low-resistance metals such as aluminum (Al) and copper (Cu). The first metal electrode 11 has a thickness of, for example, 200 nm. A first semiconductor layer 12 is disposed on the first metal electrode 11. The first semiconductor layer 12 has a substantially rectangular shape, for example, as shown in FIG. 4. The first semiconductor layer 12 is, for example, an amorphous silicon layer. The first semiconductor layer 12 has a thickness of, for example, 200 nm. A first ohmic contact layer 13 is disposed on the first semiconductor layer 12. The first ohmic contact layer 13 is, for example, an amorphous silicon layer doped with donor atoms as impurities. Hereinafter, the amorphous silicon layer doped with donor atoms as impurities will be referred to as an n+ amorphous silicon layer. The n+ amorphous silicon layer has a thickness of, for example, 50 nm. The first insulating layer 14 is disposed so as to cover the first metal electrode 11, the first semiconductor layer 12, and the first ohmic contact layer 13. The first insulating layer 14 is, for example, a silicon nitride (SiN) film. The first insulating layer 14 has a thickness of, for example, 400 nm. A portion of the first insulating layer 14 is not disposed on the first ohmic contact layer 13 in the insulating layer-removed portion RM1. The first transparent electrode 16 is disposed on the first insulating layer 14. In particular, the first transparent electrode 16 is disposed so as to cover the first ohmic contact layer 13 where the first insulating layer 14 is not disposed. The first transparent electrode 16 is, for example, a film of an oxide of an alloy of indium and titanium (ITO). In addition to ITO, examples of transparent electrodes include an oxide of an alloy of indium and zinc (IZO) and an oxide of aluminum and zinc (AlZn oxide). The first transparent electrode 16 has a thickness of, for example, 100 nm. The first transparent electrode 16 and the first ohmic contact layer 13 are in contact with each other and electrically connected.

[0040] A Schottky barrier portion S is formed between the first metal electrode 11 and the first semiconductor layer 12. Meanwhile, due to the presence of the first ohmic contact layer 13, the first transparent electrode 16, the first ohmic contact layer 13, and the first semiconductor layer 12 are in ohmic contact, and no Schottky barrier is formed. The first metal electrode 11, the first semiconductor layer 12, the first ohmic contact layer 13, and the first transparent electrode 16 form a Schottky diode. A schematic diagram of the diode circuit is shown on the right side of Figure 5. As shown in this schematic diagram, a Schottky diode is realized, with the forward direction being from the first metal electrode 11 to the first transparent electrode 16.

[0041] The Schottky barrier portion S occurs at the interface between the first metal electrode 11 and the first semiconductor layer 12. This allows the thickness of the first semiconductor layer 12 to be thin. However, if the first semiconductor layer 12 is too thin, the electric field in the Schottky barrier portion will concentrate, increasing the leakage current. On the other hand, if the amorphous silicon layer is too thick, the resistance will increase and the photocurrent will decrease. In this embodiment, for example, an amorphous silicon layer with a thickness of 200 nm is disposed. The thickness of the amorphous silicon layer is preferably 50 nm or more and 500 nm or less.

[0042] If a PIN diode is used instead of a Schottky diode, the amorphous silicon layer is thick, for example, about 1-2 microns. Light cannot pass through the amorphous silicon layer. However, the first semiconductor layer 12 made of amorphous silicon according to the present invention is thin, for example, 200 nm, so that external light L passes through. The external light L reaches the Schottky barrier portion S over the entire surface of the first semiconductor layer 12 made of amorphous silicon. A photosensing unit 200 with a wide light receiving area can be realized with a simple configuration.

[0043] In this embodiment, external light L is incident from the side where the first transparent electrode 16 is disposed, that is, from the upper side of the page in FIG. 5 . The first transparent electrode 16 and the first insulating layer 14 have high optical transparency. The external light L passes through the first transparent electrode 16 and the first insulating layer 14. The external light L is incident on the interface between the first semiconductor layer 12 and the first metal electrode 11, where a Schottky barrier exists. The external light L is absorbed by the first semiconductor layer 12. The external light L is incident from the side of the first transparent electrode 16 toward the first semiconductor layer 12. Then, the charge carrier pairs in the Schottky barrier are released. The free charge carriers provide a photocurrent.

[0044] 6 is a cross-sectional view of the photosensing section 200 taken along line II' in FIG.

[0045] The photodiode 110 shown in Fig. 6 is a modified example of the photodiode 110 shown in Fig. 5, and has two layers of first transparent electrodes 16. The two layers of first transparent electrodes 16 are distinguished by being referred to as a lower first transparent electrode 16a and an upper first transparent electrode 16b, respectively.

[0046] The photodiode 110 includes a first metal electrode 11, a first semiconductor layer 12, a first ohmic contact layer 13, a first transparent electrode 16, a first insulating layer 14, and a second insulating layer 17. This photodiode 110 is compared with the photodiode 110 shown in FIG. 5. The photodiode 110 shown in FIG. 6 and the photodiode 110 shown in FIG. 5 share a common configuration in which the first metal electrode 11, the first semiconductor layer 12, and the first ohmic contact layer 13 are arranged in this order on a glass substrate 1. In the photodiode 110 shown in FIG. 6, the lower first transparent electrode 16a is arranged on the entire surface of the first ohmic contact layer 13. The photodiode 110 shown in FIG. 6 and the photodiode 110 shown in FIG. 5 share a common configuration in that the first insulating layer 14 is formed on the first ohmic contact layer 13, and an insulating layer-removed portion RM1 is provided as a region where the first insulating layer 14 is absent. In the photodiode 110 shown in FIG. 6, the upper first transparent electrode 16b is provided on the first insulating layer 14. The upper first transparent electrode 16b is disposed so as to cover the insulating layer removed portion RM1. This arrangement of the upper first transparent electrode 16b so as to cover the insulating layer removed portion RM1 is similar to the arrangement of the first transparent electrode 16 in the photodiode 110 of FIG. 5, in which the first transparent electrode 16 is disposed so as to cover the insulating layer removed portion RM1. As will be described later, in the configuration of FIG. 5, when the first insulating layer 14 is patterned, the first ohmic contact layer 13 may also be patterned. In the configuration of FIG. 6, the lower first transparent electrode 16a acts as a stopper, reducing the possibility of the first ohmic contact layer 13 being patterned. The configuration of FIG. 5 is simple and shows a basic configuration. The configuration of FIG. 6 is more reliable. Furthermore, a second insulating layer 17 is disposed on the upper first transparent electrode 16b.

[0047] The readout circuit 120 will be described with reference to Figures 4 and 6. The readout circuit 120 has a signal readout circuit thin film transistor 121 and a signal readout electrode 3. The signal readout circuit thin film transistor 121 has a second metal electrode 21, a third insulating layer 24, a second semiconductor layer 22, a second transparent electrode 26, a fourth insulating layer 27, a third metal electrode 28, and a third transparent electrode 29.

[0048] The second metal electrode 21 is disposed on the glass substrate 1. The second metal electrode 21 and the first metal electrode 11 are formed simultaneously as described below and are composed of the same layer. Here, the term "same layer" includes layers formed simultaneously, layers of substantially the same thickness, and layers of the same material. The same applies hereinafter. This process is a metal electrode deposition process for simultaneously forming the first metal electrode 11 and the second metal electrode 21. The second metal electrode 21 is, for example, an alloy of molybdenum and tantalum. The second metal electrode 21 has a thickness of, for example, 200 nm. The second metal electrode 21 also constitutes the scanning electrode 2 shown in FIG. 4. As shown in FIG. 4, a portion of the scanning electrode 2 extends in a branch-like manner and constitutes a part of the signal readout circuit thin film transistor 121. This extended portion constitutes the first gate electrode 21a of the signal readout circuit thin film transistor 121.

[0049] The third insulating layer 24 is disposed on the second metal electrode 21 so as to cover the second metal electrode 21. The third insulating layer 24 is, for example, a silicon nitride (SiN) film. The third insulating layer 24 has a thickness of, for example, 400 nm. The third insulating layer 24 and the first insulating layer 14 are formed simultaneously as described below and are composed of the same layer. This process is an insulating layer formation process in which the first insulating layer 14 and the third insulating layer 24 are formed simultaneously.

[0050] The signal readout electrode 3 is provided on the third insulating layer 24. The signal readout electrode 3 is a metal electrode made of, for example, chromium (Cr), aluminum (Al), or titanium (Ti). As shown in FIG. 4, the signal readout electrode 3 extends in the vertical direction of the two-dimensional photosensor 100. A portion of the signal readout electrode 3 extends horizontally in a branch-like manner, for example, to the right in FIG. 4. The extended portion of the signal readout electrode 3 constitutes a part of the readout circuit 120, as shown on the left side of FIG. 6. The extended portion of the signal readout electrode 3 overlaps and is electrically connected to a second transparent electrode 26 (described later), thereby forming a metal source electrode 3a and a metal drain electrode 3b. The metal source electrode 3a and the metal drain electrode 3b function to reduce the resistance of the transparent source electrode 26a and the transparent drain electrode 26b of the second transparent electrode 26, whereas the second transparent electrode 26 alone has a high resistance.

[0051] The second transparent electrode 26 is disposed on the third insulating layer 24 and on the extending portion of the scanning electrode 2, i.e., the first gate electrode 21a, so as to partially overlap the first gate electrode 21a. The second transparent electrode 26 is, for example, an ITO film. The second transparent electrode 26 has a thickness of, for example, 100 nm. The second transparent electrode 26 constitutes a transparent source electrode 26a and a transparent drain electrode 26b of the signal readout circuit thin film transistor 121. The transparent drain electrode 26b, which is a part of the second transparent electrode 26, is electrically connected to the first transparent electrode 16. Alternatively, as described below, the second transparent electrode 26 and the first transparent electrode 16 are formed simultaneously and constituted by the same layer. This process is a transparent electrode film formation process in which the first transparent electrode 16 and the second transparent electrode 26 are formed simultaneously.

[0052] The second semiconductor layer 22 is arranged in an island shape as shown in Fig. 4. The second semiconductor layer 22 is arranged on the third insulating layer 24 and overlapping with the second transparent electrode 26 as shown in Fig. 6. The second semiconductor layer 22 is made of a transparent oxide semiconductor (hereinafter referred to as IGZO) composed of, for example, indium (In), gallium (Ga), zinc (Zn), and oxygen (O).

[0053] The fourth insulating layer 27 is disposed on the second semiconductor layer 22 and the second transparent electrode 26 so as to cover them. The fourth insulating layer 27 and the second insulating layer 17 may be formed simultaneously as described below, and are composed of the same layer. This step is an insulating layer formation step in which the second insulating layer 17 and the fourth insulating layer 27 are formed simultaneously.

[0054] The third metal electrode 28 is disposed at a position overlapping the second metal electrode 21 when viewed in a direction perpendicular to the glass substrate 1, i.e., from the top of the paper. The second metal electrode 21 functions as the first gate electrode 21a, and the third metal electrode 28 functions as the second gate electrode 21b. The first gate electrode 21a and the second gate electrode 21b function as the gate electrodes of the signal readout circuit thin film transistor 121, and control the ON / OFF switching of the signal readout circuit thin film transistor 121. The third transparent electrode 29 is disposed at a position overlapping the third metal electrode 28 when viewed in a direction perpendicular to the glass substrate 1, i.e., from the top of the paper.

[0055] A method for manufacturing the photosensing unit 200 shown in Fig. 6 will be described with reference to Fig. 7 to Fig. 14. Fig. 7 to Fig. 14 are cross-sectional views showing each manufacturing step of the photosensing unit 200. The photosensing unit 200 has a photodiode 110 and a readout circuit 120.

[0056] In the first embodiment, as will be described in detail later, the photodiode 110 is formed, and then the signal readout circuit thin-film transistor 121 having IGZO as a semiconductor layer is formed. This order of formation is preferred. If the photodiode 110 is manufactured from IGZO, hydrogen is added to the IGZO from amorphous silicon during the manufacturing process of the photodiode 110, which may make it difficult to obtain favorable characteristics for the IGZO thin-film transistor.

[0057] As shown in FIG. 7, a first metal electrode 11 and a second metal electrode 21 are simultaneously formed on a glass substrate 1. This process is a metal electrode film formation process in which the first metal electrode 11 and the second metal electrode 21 are simultaneously formed. This formation process is one of the processes in which layers constituting a photodiode 110 and a signal readout circuit thin-film transistor 121 are simultaneously formed or deposited. For example, a metal thin film made of chromium, aluminum, titanium, or the like is formed by sputtering. The metal thin film has a thickness of, for example, approximately 200 nm. A photoresist is applied to this thin film. A pattern of the metal thin film is formed by photolithography. For example, the portions of the metal thin film not covered by the resist are etched by chlorine-based dry etching. The first metal electrode 11 has, for example, the pattern shown in the plan view of FIG. 4. The second metal electrode 21 has, for example, the pattern shown in the plan view of FIG. 4.

[0058] Next, as shown in FIG. 8, a first semiconductor layer 12, a first ohmic contact layer 13, and a lower first transparent electrode 16a are successively stacked to form a laminate. The first semiconductor layer 12 is, for example, an amorphous silicon (a-Si) layer. The first ohmic contact layer 13 is, for example, an n+ amorphous silicon (n+a-Si) layer. The lower first transparent electrode 16a is, for example, ITO. The laminate is patterned into islands through a dry etching process. The island pattern of the laminate overlaps the island pattern of the first metal electrode 11, as shown in FIG. 4, for example, and has a smaller area than the island pattern of the first metal electrode 11.

[0059] Next, as shown in FIG. 9, the first insulating layer 14 and the third insulating layer 24 are simultaneously formed. The first insulating layer 14 and the third insulating layer 24 are composed of the same layer. This is an insulating layer deposition process that simultaneously forms the insulating layer for the photodiode 110 and the insulating layer for the signal readout circuit thin-film transistor 121. The first insulating layer 14 and the third insulating layer 24 are, for example, SiN films. The SiN film is formed, for example, by plasma CVD or the like. The SiN film is patterned, for example, by SF6-based dry etching. In particular, the patterning is performed so that a portion of the lower first transparent electrode 16a is exposed. Here, the lower first transparent electrode 16a functions as an etching stopper. Since the etching stops at the first transparent electrode 16a, the n+ amorphous silicon is not etched away. A configuration without the first transparent electrode 16a, as shown in FIG. 5, is also effective. Without the lower first transparent electrode 16a, precise control of the etching end point of the SF6-based dry etching is required. Because there is no etching stopper, there is a possibility that the n+ amorphous silicon will be etched away. To prevent this, the etching end point must be precisely controlled.

[0060] Next, as shown in FIG. 10, the signal readout electrode 3 is formed. The signal readout electrode 3 is a metal thin film made of, for example, chromium (Cr), aluminum (Al), or titanium (Ti). After the metal thin film is formed, it is patterned by chlorine-based dry etching. Next, as shown in FIG. 11, the upper first transparent electrode 16b is formed and the second transparent electrode 26 is formed at the same time. The upper first transparent electrode 16b and the second transparent electrode 26 are configured in the same layer. This process is a transparent electrode film formation process in which the upper first transparent electrode 16b and the second transparent electrode 26 are simultaneously formed. The second transparent electrode 26 constitutes the transparent source electrode 26a and the transparent drain electrode 26b of the signal readout circuit thin film transistor 121. The transparent drain electrode 26b is continuous with and electrically connected to the upper first transparent electrode 16b of the photodiode 110.

[0061] 12, a second semiconductor layer 22 is formed. The second semiconductor layer 22 is, for example, an IGZO layer. The IGZO layer is formed by sputtering using an oxide semiconductor target containing In, Ga, and Zn. The IGZO film is etched using an organic acid such as citric acid or oxalic acid as an etchant.

[0062] Next, as shown in Fig. 13, a second insulating layer 17 and a fourth insulating layer 27 are simultaneously formed. The second insulating layer 17 and the fourth insulating layer 27 are configured from the same layer. This process is an insulating layer deposition process in which the second insulating layer 17 and the fourth insulating layer 27 are simultaneously formed. The second insulating layer 17 and the fourth insulating layer 27 are made of, for example, silicon oxide (SiO2), and are formed by, for example, a plasma CVD method.

[0063] Next, as shown in FIG. 14, a third metal electrode 28 and a third transparent electrode 29 are laminated and patterned. The third metal electrode 28 is a metal electrode made of, for example, chromium (Cr), aluminum (Al), or titanium (Ti). The third metal electrode 28 functions as the second gate electrode 21b in the signal readout circuit thin-film transistor 121. This configuration is conventionally known as a double-gate configuration. The third metal electrode 28 assists the second metal electrode 21 in functioning as the first gate electrode 21a. The third transparent electrode 29 covers the third metal electrode 28 and serves to prevent deterioration of the third metal electrode 28.

[0064] (Variation 1) In the embodiment described above, as shown in FIG. 6, in the photodiode 110 and the signal readout circuit thin-film transistor 121, the first semiconductor layer 12 is made of amorphous silicon and the second semiconductor layer 22 is made of IGZO, which are different from each other. In Modification 1, the first semiconductor layer 12 and the second semiconductor layer 22 are also different. However, in Modification 1, the layers in which the components of the photodiode 110 are formed are different. Modification 1 will be described with reference to FIGS. 15 and 16. FIG. 15 is a plan view of a photosensing section 200 according to Modification 1. FIG. 16 is a cross-sectional view of the photosensing section 200 according to Modification 1.

[0065] In Modification 1, as shown in FIG. 16 , the first metal electrode 11 is formed in the same layer as the signal readout electrode 3. This process is a metal electrode deposition process in which the first metal electrode 11 and the signal readout electrode 3 are simultaneously formed. Compare FIG. 15 with FIG. 4 . In FIG. 4 , the first metal electrode 11, which determines the reference voltage Vb of the photodiode 110, runs horizontally in the figure, parallel to the scanning electrode 2. This is because the first metal electrode 11 is formed in the same layer as the scanning electrode 2. On the other hand, in FIG. 15 showing Modification 1, the first metal electrode 11 is arranged vertically in the figure, parallel to the signal readout electrode 3. The first metal electrode 11 is arranged parallel to the signal readout electrode 3 so that the first metal electrode 11 and the signal readout electrode 3 do not intersect. This is because the first metal electrode 11 is formed in the same layer as the signal readout electrode 3. A reference voltage Vb, for example, −1 V, is applied to the first metal electrode 11.

[0066] The structure and manufacturing method of the photodiode 110 in the first modification will be described with reference to FIG.

[0067] A second metal electrode 21 is disposed on the glass substrate 1. As shown in Fig. 15, the second metal electrode 21 extends in a branch-like manner from the scanning electrode 2 and functions as a first gate electrode 21a of the signal readout circuit thin film transistor 121. The second metal electrode 21 is made of, for example, a laminate of titanium, aluminum and titanium, aluminum, molybdenum, copper, or the like.

[0068] Next, the first insulating layer 14 and the third insulating layer 24 are simultaneously formed. This is an insulating layer deposition process in which the first insulating layer 14 and the third insulating layer 24 are simultaneously formed. The third insulating layer 24 is made of, for example, silicon nitride (SiN). The third insulating layer 24 has a thickness of, for example, 400 nm.

[0069] Next, the first metal electrode 11 is formed on the first insulating layer 14 (the same layer as the third insulating layer 24), and at the same time, the signal readout electrode 3 of the signal readout circuit thin-film transistor 121 is formed on the third insulating layer 24. The first metal electrode 11 and the signal readout electrode 3 are composed of the same layer. This is a metal electrode film formation process in which the first metal electrode 11 and the signal readout electrode 3 are simultaneously formed. As shown in FIG. 15, the first metal electrode 11 extends linearly vertically and has a rectangular extension. The signal readout electrode 3 also has an extension as shown in FIG. 15. The extension does not contact the second semiconductor layer 22 described below, but is located close to the channel portion of the second semiconductor layer 22. For the first metal electrode 11 and the signal readout electrode 3, an alloy of molybdenum and tantalum (MoTa), for example, is suitable.

[0070] As shown in FIG. 16 , a fourth transparent electrode 18 is formed on the first metal electrode 11 so as to cover the first metal electrode 11. A second transparent electrode 26 is formed at the same time. This process is a transparent electrode film formation process in which the fourth transparent electrode 18 and the second transparent electrode 26 are simultaneously formed. The fourth transparent electrode 18 and the second transparent electrode 26 are made of, for example, ITO. The fourth transparent electrode 18 and the second transparent electrode 26, the first metal electrode 11, and the signal readout electrode 3 are patterned by a wet process using, for example, hydrochloric acid or oxalic acid, or a dry process. The second transparent electrode 26 is patterned to form a transparent source electrode 26 a and a transparent drain electrode 26 b.

[0071] Next, the first semiconductor layer 12, the first ohmic contact layer 13, and the lower first transparent electrode 16a are sequentially formed and then collectively patterned into an island shape. The first semiconductor layer 12 is amorphous silicon, the first ohmic contact layer 13 is an n+ amorphous silicon layer, and the lower first transparent electrode 16a is ITO. For example, a chlorine-based dry etching method is used for patterning. During the collectively patterning into an island shape, the lower first transparent electrode 16a functions as a so-called etching stopper that prevents the first ohmic contact layer 13 from being etched.

[0072] Next, a second semiconductor layer 22 is formed. The second semiconductor layer 22 includes, for example, IGZO. The IGZO layer is formed by a sputtering method using, for example, an oxide semiconductor target containing In, Ga, and Zn. The IGZO film is etched using, for example, an organic acid such as citric acid or oxalic acid as an etchant.

[0073] The second insulating layer 17 is formed to cover the lower first transparent electrode 16a. A portion of the second insulating layer 17 is removed from above the lower first transparent electrode 16a. The lower first transparent electrode 16a prevents the etching of the second insulating layer 17 from eroding the first ohmic contact layer 13. A fourth insulating layer 27 is formed simultaneously with the second insulating layer 17. The fourth insulating layer 27 and the second insulating layer 17 are composed of the same layer. This process is an insulating layer deposition process in which the second insulating layer 17 and the fourth insulating layer 27 are simultaneously formed. The second insulating layer 17 and the fourth insulating layer 27 are made of, for example, silicon oxide (SiOx). A portion of the fourth insulating layer 27 is removed from the portion that will form the transparent drain electrode 26b. The portion from which the fourth insulating layer 27 is removed functions as the first contact hole portion C1.

[0074] A third metal electrode 28 is formed and patterned. The third metal electrode 28 is, for example, an alloy of molybdenum and tantalum (MoTa). The third metal electrode 28 is patterned so as to overlap the first gate electrode 21a in a plan view, and functions as the second gate electrode 21b.

[0075] The upper first transparent electrode 16b is formed and patterned so as to cover the lower first transparent electrode 16a and the first contact hole portion C1. The upper first transparent electrode 16b is formed simultaneously with the third transparent electrode 29. This process is a transparent electrode film formation process in which the upper first transparent electrode 16b and the third transparent electrode 29 are formed simultaneously. The upper first transparent electrode 16b is electrically connected to the transparent drain electrode 26b through the first contact hole portion C1.

[0076] The photocurrent generated in the photodiode 110 flows from the first transparent electrode 16 through the first contact hole C1 to the transparent drain electrode 26b, and then reaches the transparent source electrode 26a as the first gate electrode 21a and the second gate electrode 21b are turned on. A signal is transmitted from the transparent source electrode 26a through the signal readout electrode 3 to the signal processing circuit 150 shown in FIG.

[0077] Although not shown in FIG. 16, the second gate electrode 21b is electrically connected to the first gate electrode 21a. The second gate electrode 21b cooperates with the first gate electrode 21a to enhance the switching function of the signal readout circuit thin film transistor 121. Furthermore, a configuration in which only the second gate electrode 21b is formed and the first gate electrode 21a is not present may also be used. This configuration is a top-gate only configuration. In this configuration, IGZO is suitable for the second semiconductor layer 22 because IGZO has high mobility.

[0078] (Embodiment 2) In the first embodiment, the first semiconductor layer 12 of the photodiode 110 and the second semiconductor layer 22 of the signal readout circuit thin film transistor 121 are different semiconductor layers. In contrast, in the second embodiment, the first semiconductor layer of the photodiode 110 and the second semiconductor layer 22 of the signal readout circuit thin film transistor 121 are composed of the same semiconductor layer and are deposited simultaneously. This process is a semiconductor layer deposition process in which the first semiconductor layer 12 and the second semiconductor layer 22 are formed simultaneously. The structure and manufacturing method will be described with reference to FIGS. 17 to 24. FIG. 17 is a cross-sectional view of a photosensing section 200 according to the second embodiment. FIGS. 18 to 24 are cross-sectional views of the photosensing section 200 in each manufacturing process.

[0079] The photosensing unit 200 has a photodiode 110 and a readout circuit 120. The readout circuit 120 has a signal readout circuit thin film transistor 121. The photodiode 110 has a Schottky diode with a Schottky barrier portion S. The Schottky diode is the photodiode 110 that responds to external light L. The signal readout circuit thin film transistor 121 is a channel-etch type thin film transistor.

[0080] The photodiode 110 has a first metal electrode 11, a first insulating layer 14, a first semiconductor layer 12, a first ohmic contact layer 13, a first transparent electrode 16, and a second insulating layer 17. A Schottky barrier portion S appears at the interface between the first metal electrode 11 and the first semiconductor layer 12. A Schottky diode is configured with the direction from the first metal electrode 11 to the first transparent electrode 16 as the forward direction.

[0081] The glass substrate 1 is, for example, alkali-free glass, such as borosilicate glass. The glass substrate 1 has a thickness of, for example, 0.5 to 0.7 mm. The first metal electrode 11 is disposed on the glass substrate 1. The first metal electrode 11 has, for example, a substantially rectangular shape. The first metal electrode 11 is, for example, an alloy of molybdenum and tantalum. The first metal electrode 11 has a thickness of, for example, 200 nm.

[0082] A first insulating layer 14 is disposed so as to cover the first metal electrode 11 except for the insulating layer removal portion RM1. The film formation process will be described in detail later. After the first insulating layer 14 is formed so as to cover the first metal electrode 11, a portion of the first insulating layer 14 is removed at the insulating layer removal portion RM1 above the first metal electrode 11. The first insulating layer 14 is, for example, a silicon nitride / silicon oxide (SiN / SiO2) film. The first insulating layer 14 has a thickness of, for example, 400 nm. A first semiconductor layer 12 is disposed on the first metal electrode 11. The first semiconductor layer 12 has, for example, a substantially rectangular shape. The first semiconductor layer 12 is, for example, an amorphous silicon layer. The first semiconductor layer 12 has a thickness of, for example, 200 nm. A first ohmic contact layer 13 is disposed on the first semiconductor layer 12. The first ohmic contact layer 13 is, for example, an n+ amorphous silicon layer. The n+ amorphous silicon layer has a thickness of, for example, 50 nm. The first transparent electrode 16 is disposed so as to cover the first insulating layer 14 and the first ohmic contact layer 13. The first transparent electrode 16 is, for example, a film of an oxide of an alloy of indium and titanium (ITO). The first transparent electrode 16 has a thickness of, for example, 100 nm. The first transparent electrode 16 and the first ohmic contact layer 13 are in contact with each other and are electrically connected. The second insulating layer 17 is disposed so as to cover the first transparent electrode 16.

[0083] A Schottky barrier portion S is formed between the first metal electrode 11 and the first semiconductor layer 12. Meanwhile, due to the presence of the first ohmic contact layer 13, the first transparent electrode 16, the first ohmic contact layer 13, and the first semiconductor layer 12 are in ohmic contact, and no Schottky barrier is formed. The first metal electrode 11, the first semiconductor layer 12, the first ohmic contact layer 13, and the first transparent electrode 16 form a Schottky diode. A schematic diagram of the diode circuit is shown on the right side of Figure 17. As shown in this schematic diagram, a Schottky diode is realized, with the forward direction being from the first metal electrode 11 to the first transparent electrode 16.

[0084] The Schottky barrier portion S occurs at the interface between the first metal electrode 11 and the first semiconductor layer 12. Therefore, the thickness of the first semiconductor layer 12 does not affect the occurrence of the Schottky barrier. This allows the thickness of the first semiconductor layer 12 to be thin. In this embodiment, for example, an amorphous silicon layer having a thickness of 200 nm is disposed. The thickness of the amorphous silicon layer is preferably 50 nm or more and 500 nm or less. In the case of a PN-type diode, for example, instead of a Schottky barrier, the amorphous silicon layer is thick, for example, about 1 to 2 microns. Unlike a PN-type diode, the photodiode 110 according to the present disclosure can realize a photosensing unit 200 with a wide light receiving area with a simple configuration.

[0085] In this embodiment, as shown in FIG. 17 , external light L is incident from the side where the first transparent electrode 16 is disposed. The first transparent electrode 16 and the second insulating layer 17 are highly transparent. The external light L passes through the first transparent electrode 16 and the second insulating layer 17. The external light L is incident on the interface between the first semiconductor layer 12 and the first metal electrode 11, where a Schottky barrier is present. The external light L is absorbed by the first semiconductor layer 12. The external light L is incident from the side of the first transparent electrode 16 toward the first semiconductor layer 12. Then, the charge carrier pairs in the Schottky barrier are released. The free charge carriers provide a photocurrent.

[0086] The readout circuit 120 has a signal readout circuit thin film transistor 121 and a signal readout electrode 3. The signal readout circuit thin film transistor 121 has a second metal electrode 21, a third insulating layer 24, a second semiconductor layer 22, a second ohmic contact layer 23, a transparent source electrode 26a and a transparent drain electrode 26b each composed of a metal source electrode 3a, a metal drain electrode 3b, and a second transparent electrode 26, and a fourth insulating layer 27. The source electrode has a laminated configuration of a metal source electrode 3a formed by extending in a branch-like manner from the signal readout electrode 3 and a transparent source electrode 26a composed of the second transparent electrode 26. The drain electrode has a laminated configuration of a metal drain electrode 3b formed in the same layer as the signal readout electrode 3 and a transparent drain electrode 26b composed of the second transparent electrode 26.

[0087] The second metal electrode 21 is disposed on the glass substrate 1. The second metal electrode 21 and the first metal electrode 11 are formed simultaneously in the same layer, as described below. This process is a metal electrode deposition process for simultaneously forming the first metal electrode 11 and the second metal electrode 21. The second metal electrode 21 is, for example, an alloy of molybdenum and tantalum. The second metal electrode 21 has a thickness of, for example, 200 nm. The second metal electrode 21 constitutes the scanning electrode 2 shown in FIG. 4. As shown in FIG. 4, a portion of the scanning electrode 2 extends in a branch-like manner and constitutes a part of the signal readout circuit thin film transistor 121. This extended portion constitutes the first gate electrode 21a of the signal readout circuit thin film transistor 121.

[0088] The third insulating layer 24 is disposed on the second metal electrode 21 so as to cover the second metal electrode 21. The third insulating layer 24 is, for example, a silicon nitride (SiN) film. The third insulating layer 24 has a thickness of, for example, 400 nm. The third insulating layer 24 and the first insulating layer 14 are formed simultaneously as described below, and are formed in the same layer. This process is an insulating layer formation process in which the first insulating layer 14 and the third insulating layer 24 are formed simultaneously.

[0089] The second semiconductor layer 22 is arranged in an island shape to cover the first gate electrode 21a as shown in FIG. 4. The second semiconductor layer 22 is arranged on a third insulating layer 24 as shown in FIG. 17. An amorphous silicon layer is used as the second semiconductor layer 22, for example. A second ohmic contact layer 23 is provided on the amorphous silicon layer. The second ohmic contact layer 23 is made of, for example, n+ amorphous silicon. As will be described in detail later, the first semiconductor layer 12 and the second semiconductor layer 22 are formed simultaneously and are made of the same layer. The first ohmic contact layer 13 and the second ohmic contact layer 23 are formed simultaneously and are made of the same layer. This process is an ohmic contact layer deposition process in which the first ohmic contact layer 13 and the second ohmic contact layer 23 are formed simultaneously. The first semiconductor layer 12 and the second semiconductor layer 22 have a thickness of, for example, 200 nm. The n+ amorphous silicon layers constituting the first ohmic contact layer 13 and the second ohmic contact layer 23 have a thickness of, for example, 50 nm.

[0090] The signal readout electrode 3 is provided on the third insulating layer 24 and the second ohmic contact layer 23. The signal readout electrode 3 is a metal electrode made of, for example, chromium (Cr), aluminum (Al), or titanium (Ti). As shown in FIG. 4, the signal readout electrode 3 extends in the vertical direction of the two-dimensional photosensor 100. A portion of the signal readout electrode 3 extends in a branch-like manner in the horizontal direction, for example, to the right in FIG. 4. The extended portion of the signal readout electrode 3 constitutes a part of the readout circuit 120, as shown at the left end of FIG. 17.

[0091] As shown in FIG. 4 , the second transparent electrode 26 is provided on the second ohmic contact layer 23 at two locations, sandwiching the first gate electrode 21a. One functions as a transparent source electrode 26a of the signal readout circuit thin film transistor 121, and the other functions as a transparent drain electrode 26b of the signal readout circuit thin film transistor 121. The transparent drain electrode 26b, which is a part of the second transparent electrode 26, is electrically connected to the first transparent electrode 16. In this embodiment, as described later, the second transparent electrode 26 and the first transparent electrode 16 are formed simultaneously and are configured from the same layer. This process is a transparent electrode film formation process in which the first transparent electrode 16 and the second transparent electrode 26 are simultaneously formed. As shown in FIG. 17 , the transparent drain electrode 26b, which is a part of the second transparent electrode 26, extends to become the first transparent electrode 16. The transparent drain electrode 26b is disposed on the first ohmic contact layer 13 so as to cover the first ohmic contact layer 13. The second transparent electrode 26 and the first transparent electrode 16 are, for example, films of an oxide of an alloy of indium and titanium (ITO), and each of the first transparent electrode 16 and the second transparent electrode 26 has a thickness of, for example, 100 nm.

[0092] The second ohmic contact layer 23, the metal source electrode 3a, the transparent source electrode 26a, the metal drain electrode 3b, and the transparent drain electrode 26b are patterned and disposed on the second semiconductor layer 22 in two parts.

[0093] The fourth insulating layer 27 is disposed on the second transparent electrode 26. The fourth insulating layer 27 is made of, for example, silicon nitride (SiN). As will be described later, the second insulating layer 17 and the fourth insulating layer 27 are formed simultaneously and are made of the same layer. This process is an insulating layer deposition process in which the second insulating layer 17 and the fourth insulating layer 27 are formed simultaneously.

[0094] External light L is incident on the photodiode 110, causing a photocurrent to be generated in the photodiode 110. An ON voltage (e.g., 15 V) is applied to the first gate electrode 21a, and the transparent drain electrode 26b and the transparent source electrode 26a become conductive. The photocurrent is transmitted from the first transparent electrode 16 through the second transparent electrode 26, the transparent drain electrode 26b, the transparent source electrode 26a, and the signal readout electrode 3 to the signal processing circuit 150.

[0095] A method for manufacturing the photosensing unit 200 shown in Fig. 17 will be described with reference to Fig. 4 and Fig. 18 to Fig. 24. Fig. 18 to Fig. 24 are cross-sectional views of the photosensing unit 200 taken along line II' in Fig. 4 in each manufacturing step.

[0096] As shown in FIG. 18, a first metal electrode 11 and a second metal electrode 21 are simultaneously formed on a glass substrate 1. For example, a thin metal film made of chromium, aluminum, titanium, or the like is formed by sputtering. The thin metal film has a thickness of, for example, approximately 200 nm. A photoresist is applied to this thin film. A pattern of the thin metal film is formed by photolithography. For example, the portions of the thin metal film not covered by the resist are etched by chlorine-based dry etching. The first metal electrode 11 has, for example, the pattern shown in the plan view of FIG. 4. The second metal electrode 21 has, for example, the pattern shown in the plan view of FIG. 4. This process is a metal electrode film formation process in which the first metal electrode 11 and the second metal electrode 21 are simultaneously formed.

[0097] Next, as shown in FIG. 19, a first insulating layer 14 and a third insulating layer 24 are simultaneously formed. The first insulating layer 14 and the third insulating layer 24 are configured from the same layer. This process is an insulating layer deposition process in which the first insulating layer 14 and the third insulating layer 24 are simultaneously formed. The first insulating layer 14 and the third insulating layer 24 are, for example, SiN films. The SiN film is formed by, for example, a plasma CVD method. The SiN film is patterned by, for example, SF6-based dry etching. In particular, the patterning is performed so that a portion of the first metal electrode 11 is exposed. In the photodiode 110, a second contact portion C2 is formed on the first metal electrode 11.

[0098] Next, as shown in FIG. 20 , a first semiconductor layer 12, a second semiconductor layer 22, a first ohmic contact layer 13, and a second ohmic contact layer 23 are successively stacked to form a stacked body. The first semiconductor layer 12 and the second semiconductor layer 22 are formed simultaneously and are composed of the same layer. This process is a semiconductor layer deposition process in which the first semiconductor layer 12 and the second semiconductor layer 22 are simultaneously formed. The first ohmic contact layer 13 and the second ohmic contact layer 23 are simultaneously formed and are composed of the same layer. This process is an ohmic contact layer deposition process in which the first ohmic contact layer 13 and the second ohmic contact layer 23 are simultaneously formed. The first semiconductor layer 12 and the second semiconductor layer 22 are, for example, amorphous silicon (a-Si) layers. The first ohmic contact layer 13 and the second ohmic contact layer 23 are, for example, n+ amorphous silicon (n+a-Si) layers. The stack is patterned into islands through an SF6-based dry etching process. The island pattern of the stack is shown in FIG. 4, for example. The first semiconductor layer 12 and the first ohmic contact layer 13 overlap the island pattern of the first metal electrode 11 and have an area equal to or smaller than the island pattern of the first metal electrode 11.

[0099] Next, as shown in FIG. 21, the signal readout electrode 3 is formed. The signal readout electrode 3 is a metal thin film made of, for example, chromium (Cr), aluminum (Al), titanium (Ti), or the like. After the metal thin film is formed, it is patterned by chlorine-based dry etching. The signal readout electrode 3 extends in a branch-like shape as shown in FIG. 4, and is also disposed on the second semiconductor layer and the second ohmic contact layer 23. The portions extending from the signal readout electrode 3 constitute a metal source electrode 3a and a metal drain electrode 3b of the signal readout circuit thin film transistor 121, as will be described later.

[0100] Next, as shown in FIG. 22, the first transparent electrode 16 and the second transparent electrode 26 are simultaneously formed. The first transparent electrode 16 and the second transparent electrode 26 are composed of the same layer. This process is a transparent electrode film formation process in which the first transparent electrode 16 and the second transparent electrode 26 are simultaneously formed. The first transparent electrode 16 is arranged in an island shape on the first semiconductor layer 12 and the first ohmic contact layer 13, as shown in FIG. 4. Meanwhile, a portion of the second transparent electrode 26 and the signal readout electrode 3 that is arranged on the first gate electrode 21a is patterned. The patterning is performed, for example, by chlorine-based dry etching. As shown in FIGS. 4 and 22, the second transparent electrodes 26 are arranged at two separate locations, sandwiching the first gate electrode 21a made of the second metal electrode 21 therebetween. One of the second transparent electrodes 26 functions as a transparent source electrode 26a, and the other second transparent electrode 26 functions as a transparent drain electrode 26b. The first transparent electrode 16 and the transparent drain electrode 26b, which is a part of the second transparent electrode 26, are integral with each other and are electrically connected.

[0101] Next, as shown in FIG. 23, the second ohmic contact layer 23 and a portion of the second semiconductor layer 22 are patterned using the transparent source electrode 26a and the transparent drain electrode 26b, which are made of the second transparent electrode 26, as a mask or resist. A channel etching portion CE is formed. SF4-based dry etching is used, for example. This method is generally called the channel etching method. Precise control of the etching end point of the SF6-based dry etching is required. Since there is no etching stopper, there is a possibility that not only the n+ amorphous silicon but also the amorphous silicon will be etched away. The etching end point must be controlled to prevent the amorphous silicon from being etched away.

[0102] Finally, as shown in Fig. 24, a second insulating layer 17 and a fourth insulating layer 27 are simultaneously formed. The second insulating layer 17 and the fourth insulating layer 27 are configured from the same layer. This process is an insulating layer deposition process in which the second insulating layer 17 and the fourth insulating layer 27 are simultaneously formed. The second insulating layer 17 and the fourth insulating layer 27 are made of, for example, silicon nitride (SiN), and are formed by, for example, a plasma CVD method.

[0103] Although not explained here, wiring is reconnected to extract signals. Contact holes are provided in the insulating layers as needed to connect different conductive layers.

[0104] (Second Modification) FIG. 25 is a cross-sectional view of a photodiode 110 according to a second modification. A fifth insulating layer 15 is disposed on the first insulating layer 14 described in the above embodiment. The fifth insulating layer 15 also functions as a dielectric layer. The first insulating layer 14 is made of silicon nitride (SiN). The fifth insulating layer 15 is made of silicon oxide (SiO2). The fifth insulating layer 15 is formed on the outermost surface of the photodiode 110 opposite the glass substrate 1. The fifth insulating layer 15 functions to reduce surface reflection. A low-reflection structure is achieved by phase difference adjustment (index matching). When external light L is incident, reflection of the external light L on the surface of the first insulating layer 14 can be suppressed. The fifth insulating layer 15 has a refractive index of 1.5 and a thickness of 90 nm, for example. This increases the amount of light reaching the Schottky barrier portion S, improving the sensitivity of the photodiode 110.

[0105] (Third Modification) 26 and 27 show an example of a photodiode 110 according to a third modification. FIG. 26 is a plan view. FIG. 27 is a cross-sectional view taken along the line II-II' in FIG. 26. In the third modification, the fifth insulating layer 15 is arranged wider than that of the second modification shown in FIG. 25. In FIG. 26, the fifth insulating layer 15 is transparent, so the first transparent electrode 16b and other elements are indicated by solid lines rather than dotted lines. The fifth insulating layer 15 is made of, for example, silicon oxide (SiO2). The fifth insulating layer 15 is arranged to cover the first insulating layer 14 and the first transparent electrode 16 (the upper first transparent electrode 16b and the lower first transparent electrode 16a). Silicon nitride (SiN) and silicon oxide (SiO2) are arranged in a layered manner in areas other than the area where the upper first transparent electrode 16b is formed. When external light L is incident, it is possible to suppress reflection of the external light L on the surfaces of the first insulating layer 14 and the first transparent electrode 16. This increases the amount of light that reaches the Schottky barrier portion S, improving the sensitivity of the photodiode 110.

[0106] (Fourth Modification) FIG. 28 is a cross-sectional view of a photodiode 110 according to a fourth modification taken along the line II' in FIG. 4. In the above embodiment, a first semiconductor layer 12 is stacked on a first metal electrode 11, and a first ohmic contact layer 13 is stacked on the first semiconductor layer 12. In the fourth modification, a first ohmic contact layer 13 is stacked on the first metal electrode 11, and a first semiconductor layer 12 is stacked on the first ohmic contact layer 13. A lower first transparent electrode 16a is stacked on the first semiconductor layer 12. A first insulating layer 14 is formed, and a portion of the first insulating layer 14 that contacts the lower first transparent electrode 16a is removed to form an insulating layer-removed portion RM1. An upper first transparent electrode 16b is disposed to cover the insulating layer-removed portion RM1. The upper first transparent electrode 16b and the lower first transparent electrode 16a are electrically connected.

[0107] The materials constituting the first metal electrode 11, the first semiconductor layer 12, the first ohmic contact layer 13, the first insulating layer 14, and the first transparent electrode 16 are the same as those described in the above embodiment.

[0108] In the fourth modification, the Schottky barrier portion S is formed at the interface between the first semiconductor layer 12 and the first transparent electrode 16a. The forward direction of the photodiode 110 is from the first transparent electrode 16 to the first metal electrode 11, as shown on the left in FIG. 28. As shown in FIG. 29, the photodiode 110 is formed in the reverse direction with respect to the drain electrode of the signal readout circuit thin film transistor 121. A reverse bias must be applied to the photodiode 110. In the first embodiment, the reference voltage Vb shown in FIG. 1 is −1 V. In contrast, the reference voltage Vb in the fourth modification is, for example, +3 V.

[0109] The signal readout circuit thin-film transistor 121 of the photodiode 110 according to the fourth modification is preferably made of IGZO as in the first embodiment. The manufacturing process described in the first embodiment can be followed. Like the fourth modification, the second embodiment uses amorphous silicon as the second semiconductor layer 22. However, the stacking order of the n+ amorphous silicon differs from that of the fourth modification. The second embodiment uses an inverted staggered thin-film transistor. It is difficult to change the stacking order of the second semiconductor layer 22 and the second ohmic contact layer 23. For this reason, it is difficult to standardize the manufacturing process in the fourth modification, as in the second embodiment. The fourth modification is preferably based on the first embodiment.

[0110] (Fifth Modification) FIG. 30 is a cross-sectional view of a photodiode 110 according to a fifth modification. In the fourth modification, a lower first transparent electrode 16a is provided. In the fifth modification, the lower first transparent electrode 16a is not provided. In the fourth modification, the lower first transparent electrode 16a functions as an etching stopper. Removal of the first insulating layer 14 does not result in removal of the first semiconductor layer 12, e.g., amorphous silicon. In the fifth modification, the etching stopper function is absent, and the first semiconductor layer 12 is partially etched. In FIG. 30, the upper portion of the first semiconductor layer 12 is etched, resulting in a concave shape. The first ohmic contact layer 13 is, for example, n+ amorphous silicon, and has a thin thickness of, for example, 50 nm. For this reason, in the first embodiment, a lower first transparent electrode 16a is provided, as shown in FIG. 6. In contrast, the first semiconductor layer 12, e.g., an amorphous silicon layer, has a thickness of, e.g., 200 nm. The first semiconductor layer 12 is thicker than the first ohmic contact layer 13. For this reason, as shown in Figure 30, there is little need for precise etching control to prevent the entire first semiconductor layer 12 from being etched. The fifth modification, as shown in Figure 30, has the advantage that the lower first transparent electrode 16a shown in Figure 28 is not required, and the process is shorter.

[0111] (Sixth Modification) FIG. 31 is a cross-sectional view of a photodiode 110 according to a sixth modified example. In the above-described embodiment, the photodiode 110 receives external light L incident from the opposite side of the glass substrate 1. The photodiode 110 according to the sixth modified example receives external light L incident from the glass substrate 1 side. The first metal electrode 11 is made of a transparent electrode. External light L is incident from the transparent first metal electrode 11 side toward the first semiconductor layer 12. The first metal electrode 11 is preferably made of, for example, AZO, which is zinc oxide doped with aluminum (Al). Alternatively, a zinc oxide (ZnO) transparent conductive film, GZO doped with gallium, or an ITO film may be used.

[0112] A first semiconductor layer 12, a first ohmic contact layer 13, and a lower first transparent electrode 16a are stacked in this order on the first metal electrode 11, and then patterned and disposed. Next, a first insulating layer 14 is stacked and patterned. An insulating layer-removed portion RM1 is formed on the lower first transparent electrode 16a. A fourth metal electrode 19 is disposed to cover the insulating layer-removed portion RM1. An upper first transparent electrode 16b is formed on the fourth metal electrode 19. The first semiconductor layer 12 is, for example, an amorphous silicon layer. The first ohmic contact layer 13 is, for example, an n+ amorphous silicon layer. The lower first transparent electrode 16a and the upper first transparent electrode 16b are, for example, ITO layers. The fourth metal electrode 19 is, for example, chromium (Cr), aluminum (Al), titanium (Ti), or the like. The fourth metal electrode 19 may be formed simultaneously with the metal source electrode 3a and the metal drain electrode 3b of the signal readout circuit thin film transistor 121 and may be configured in the same layer. This step is a metal electrode film formation step in which the fourth metal electrode 19, the metal source electrode 3a, and the metal drain electrode 3b are formed simultaneously.

[0113] External light L incident from the side opposite to the glass substrate 1 is blocked by the fourth metal electrode 19. On the other hand, external light L incident from the glass substrate 1 side passes through the first metal electrode 11 and reaches the Schottky barrier portion S formed at the interface between the first metal electrode 11 and the first semiconductor layer 12. The photodiode 110 receives the external light L and generates a photocurrent. After passing through the Schottky barrier portion S, the external light L incident from the glass substrate 1 side is reflected by the fourth metal electrode 19 and enters the Schottky barrier portion S again. Because the external light L passes through the Schottky barrier portion S twice, a highly sensitive photodiode 110 can be realized.

[0114] (Seventh Modification) In the sixth modification, the external light L incident from the glass substrate 1 side is received, and the first ohmic contact layer 13 is provided on the side of the first semiconductor layer 12 opposite to the glass substrate 1. As shown in FIG. 32, the external light L incident from the glass substrate 1 side may be received, and the first ohmic contact layer 13 may be provided on the side of the first semiconductor layer 12 facing the glass substrate 1. The position of the first ohmic contact layer 13 relative to the first semiconductor layer 12 may be on the opposite side to the position shown in the above embodiment and its modifications. In these cases, the orientation of the Schottky diode changes as shown in FIG. 29, and the reference voltage Vb changes, for example, from −1 V to +3 V.

[0115] (Eighth Modification) In the two-dimensional photosensor 100 according to the above embodiment, the photocurrent from the photodiode 110 is detected through the signal readout circuit thin-film transistor 121. This is called an active matrix system. The eighth modification discloses a two-dimensional photosensor 100 based on a direct drive system. The eighth modification will be described with reference to FIGS. 33 to 35. FIG. 33 is a circuit diagram showing an overall outline of the two-dimensional photosensor 100. FIG. 34 is a plan view of the photosensing section 200. FIG. 35 is a cross-sectional view taken along line III-III' in FIG. 34.

[0116] As shown in FIG. 33, the anodes of the photodiodes 110 are connected to a plurality of common electrodes 5 arranged in the horizontal direction. The common electrodes 5 are first metal electrodes 11 shown in FIG. 35. As shown in FIGS. 33 and 34, the common electrodes 5 extend in the left-right direction. The cathodes of the photodiodes 110 are connected to first transparent electrodes 16. As shown in FIG. 34, the first transparent electrodes 16 are connected to signal readout electrodes 3. As shown in FIGS. 33 and 34, the signal readout electrodes 3 extend in the up-down direction. As shown in FIG. 33, the signal readout electrodes 3 are connected to a signal processing circuit 150. The signal processing circuit 150 detects the in-plane distribution of the intensity of light incident on each photodiode 110 from the signal of each photodiode 110.

[0117] 33 to 35 has the advantage of not requiring the signal readout circuit thin-film transistor 121. Apart from the glass substrate 1 on which the two-dimensional photosensor 100 is mounted, the signal processing circuit 150 can be realized using a silicon integrated circuit (Si-IC).

[0118] As shown in FIG. 35, a first metal electrode 11, a first semiconductor layer 12, a first ohmic contact layer 13, and a lower first transparent electrode 16a are stacked in this order on a glass substrate 1. These layers are collectively patterned and arranged in an island shape as shown in FIG. 34. Furthermore, a first insulating layer 14 is arranged. A portion of the first insulating layer 14 above the lower first transparent electrode 16a is removed to form and arrange an insulating layer-removed portion RM1. A signal readout electrode 3 is provided on the first insulating layer 14 and patterned. An upper first transparent electrode 16b is stacked and patterned so as to cover the insulating layer-removed portion RM1 and overlap the signal readout electrode 3.

[0119] The materials constituting the glass substrate 1, the first metal electrode 11, the first semiconductor layer 12, the first ohmic contact layer 13, the first transparent electrode 16, and the first insulating layer 14 are the same as those in the above embodiment.

[0120] (Ninth Variation) The eighth modification described a direct drive system. A passive matrix system may also be employed. FIG. 36 is an overall circuit diagram of a two-dimensional photosensor 100 according to a ninth modification. A gate driver 130 applies a scan signal to the scan electrodes 2. For example, the voltage during scanning is +4 V. A voltage of +1.5 V, for example, is applied from the multiplexer 140, and a reverse bias voltage of 2.5 V is applied to the photodiodes 110. As shown in FIG. 2, a photocurrent is generated according to the illuminance of each photodiode 110. A signal processing circuit 150 derives the light illuminance based on the generated photocurrent. When not scanning, a voltage of +1.1 V, for example, is applied to the scan electrodes 2. At this time, a forward voltage of 0.4 V is applied to the photodiodes 110. At this time, as shown in FIG. 2, the photocurrent is suppressed regardless of the illuminance of each photodiode 110. The photocurrent from the photodiode 110 being scanned is provided to a multiplexer 140 and a signal processing circuit 150. By scanning the scanning electrodes 2, the illumination intensity at each photodiode 110 is estimated.

[0121] The two-dimensional photosensor 100 described above is preferably applied to a display. Examples of the display include a liquid crystal display and an organic electroluminescence (EL) display. The two-dimensional photosensor 100 according to the present invention is provided on, for example, a glass substrate 1. This glass substrate 1 may be an independent glass substrate 1 or may be a glass substrate 1 included in a display. A configuration in which the two-dimensional photosensor 100 is provided on an independent glass substrate 1 and combined with a display is generally called an on-cell system. A configuration in which the two-dimensional photosensor 100 is provided on a glass substrate 1 included in a display is generally called an in-cell system. The two-dimensional photosensor 100 according to the present invention can be applied to both the on-cell system and the in-cell system. In the on-cell system, the two-dimensional photosensor 100 is manufactured and driven independently of the display body. This makes it possible to expect application to large displays.

[0122] The present disclosure allows various embodiments and modifications without departing from the broad spirit and scope of the present invention. Furthermore, the above-described embodiments are intended to illustrate the present invention and do not limit the scope of the present invention. That is, the scope of the present invention is defined by the claims, not the embodiments. Various modifications made within the scope of the claims and the meaning of the disclosure equivalent thereto are considered to be within the scope of the present invention.

[0123] The two-dimensional photosensor 100 according to the embodiment described above provides the following advantages.

[0124] (1) The two-dimensional photosensor 100 includes a plurality of photodiodes 110 arranged in an array. The photodiodes 110 have a stack of a first metal electrode 11, a first semiconductor layer 12, a first ohmic contact layer 13, and a first transparent electrode 16. The first semiconductor layer 12 and the first ohmic contact layer 13 are arranged between the first metal electrode 11 and the first transparent electrode 16. A Schottky barrier is provided at the interface between the first semiconductor layer 12 and the first metal electrode 11 or at the interface between the first semiconductor layer 12 and the first transparent electrode 16, and the photodiodes 110 sense light incident from the side of the first transparent electrode 16 toward the first semiconductor layer 12.

[0125] This provides a two-dimensional photosensor 100 capable of detecting gradations across a relatively wide two-dimensional space such as a display. By detecting the two-dimensional distribution of shadows, brightness, etc. cast on the display and feeding that information back to the display signal, it is possible to display a display that includes the representation of actual shadows and shading, making it possible to more closely resemble the real thing, such as paper. Visibility can be ensured by increasing the brightness only in bright areas of the display. A display that is easy to see and consumes low power can be realized.

[0126] (2) In the two-dimensional photosensor 100 of (1), the first semiconductor layer 12 is made of amorphous silicon, and the first ohmic contact layer 13 is made of n+ amorphous silicon.

[0127] This allows for manufacturing in factories that do not have a P+ process for adding acceptor atoms as impurities. The two-dimensional photosensor 100 can be manufactured using the same manufacturing process as existing amorphous silicon thin-film transistors. No new manufacturing process needs to be added or modified. In conventional photosensors, such as PIN-type amorphous silicon sensors like solar cells, increasing light sensitivity requires thickening the amorphous silicon layer to approximately 1 to 2 microns to enhance light absorption. In contrast, the Schottky diode disclosed herein generates carriers at the "narrow interface" between the metal and semiconductor, eliminating the need to thicken the entire amorphous silicon film. Therefore, high sensitivity can be achieved even with a thin amorphous silicon film of approximately several hundred nanometers, which is commonly used in amorphous silicon thin-film transistor factories. Eliminating the need for a thick amorphous silicon layer improves manufacturing efficiency and enables low-cost production.

[0128] (3) In the two-dimensional photosensor 100 of (1) or (2), the first metal electrode 11 has a light-shielding property and is configured to be drawn out of the light-sensing region.

[0129] This blocks light incident from the glass substrate 1 side. Therefore, it is possible to detect only external light L incident from the side opposite to the glass substrate 1. External light L is reflected by the first metal electrode 11 and passes twice through the interface between the first metal electrode 11 and the first semiconductor layer 12, where a Schottky barrier is formed, improving sensitivity. The first metal electrode 11 serves both as a light shield and as a lead wiring. This allows for high productivity and low costs.

[0130] (4) In the two-dimensional photosensor 100 of any one of (1) to (3), the photocurrent of each of the photodiodes 110 is acquired individually through a direct connection, or is acquired by scanning through a simple matrix method.

[0131] This allows for a two-dimensional photosensor 100 that is highly productive and low cost.

[0132] (5) The two-dimensional photosensor 100 of any one of (1) to (4) includes a readout circuit 120 that reads out a signal from the photodiode 110, and the readout circuit 120 has a signal readout circuit thin-film transistor 121, and the signal readout circuit thin-film transistor 121 has at least one layer that is the same as the layer that constitutes the photodiode 110.

[0133] This makes it possible to manufacture the two-dimensional photosensor 100 and the signal readout circuit thin-film transistor 121 on an existing display manufacturing line. The application of a thin amorphous silicon (a-Si) film makes it possible to achieve both a highly sensitive photosensor and high productivity.

[0134] In the two-dimensional photosensor 100 of (6)(5), the signal readout circuit thin film transistor 121 has a second metal electrode 21, which functions as a gate electrode of the signal readout circuit thin film transistor 121, and the second metal electrode 21 is made of the same layer as the first metal electrode 11 of the photodiode 110 and is not electrically connected to each other.

[0135] This shortens the manufacturing process and makes it possible to manufacture the device in existing thin-film transistor factories.

[0136] In the two-dimensional photosensor 100 of (7) (5) or (6), the signal readout circuit thin film transistor 121 has a source electrode and a drain electrode, and the source electrode and the drain electrode include at least the same layer as the first transparent electrode 16 or the first metal electrode 11 of the photodiode 110.

[0137] This shortens the manufacturing process and makes it possible to manufacture the device in existing thin-film transistor factories.

[0138] (8) In any one of the two-dimensional photosensors 100 of (5) to (7), the signal readout circuit thin-film transistor 121 has a second semiconductor layer 22, and the second semiconductor layer 22 is made of the same layer as the first semiconductor layer 12 of the photodiode 110.

[0139] This makes it possible to obtain a highly sensitive photosensor by using the same semiconductor layer for both the signal readout circuit thin film transistor 121 and the photodiode 110. Since it is possible to use a thin amorphous silicon film that is about 1 / 10 the thickness of the amorphous silicon layer used in solar cells, high productivity can also be achieved.

[0140] (9) In the two-dimensional photosensor 100 of any one of (5) to (8), the signal readout circuit thin film transistor 121 has a second semiconductor layer 22 made of indium gallium zinc oxide.

[0141] This allows high mobility to be achieved over a large area in the signal readout circuit thin film transistor 121. It becomes possible to arrange the readout circuit 120 and the photodiode 110 over the entire surface of the display.

[0142] (10) In two-dimensional photosensor 100 of any one of (1) to (9), photodiode 110 has a dielectric layer on the outermost surface opposite glass substrate 1 to reduce surface reflection.

[0143] This increases the amount of light that reaches the Schottky barrier portion S, improving the sensitivity of the photodiode 110.

[0144] (11) A method for manufacturing a two-dimensional photosensor 100, the two-dimensional photosensor 100 comprising a plurality of arrayed photodiodes 110 and a circuit for reading out signals from the photodiodes 110, the photodiodes 110 having a stack of a first metal electrode 11, a first semiconductor layer 12, a first ohmic contact layer 13, and a first transparent electrode 16, the first semiconductor layer 12 and the first ohmic contact layer 13 being disposed between the first metal electrode 11 and the first transparent electrode 16, The method for manufacturing the two-dimensional photosensor 100 includes a step of simultaneously forming at least one layer constituting the photodiode 110 and the signal readout circuit thin film transistor 121, and a Schottky barrier is provided at the interface between the first semiconductor layer 12 and the first metal electrode 11 or the interface between the first semiconductor layer 12 and the first transparent electrode 16, and the two-dimensional photosensor 100 senses light incident from the first transparent electrode 16 side toward the first semiconductor layer 12, and the signal readout circuit includes a signal readout circuit thin film transistor 121.

[0145] This provides a two-dimensional photosensor 100 capable of detecting gradations across the entire display surface. By detecting the two-dimensional distribution of shadows, brightness, etc. cast on the display and feeding this back to the display signal, it is possible to display an image that includes actual shadows and shading, making it closer to the real thing, such as paper.

[0146] (12) In the manufacturing method of the two-dimensional photosensor 100 of (11), the signal readout circuit thin film transistor 121 has a second metal electrode 21, a second semiconductor layer 22, a second ohmic contact layer 23, a transparent source electrode 26a, and a transparent drain electrode 26b, and includes at least one of a metal electrode formation process for simultaneously forming the first metal electrode 11 and the second metal electrode 21, or a metal electrode formation process for simultaneously forming the first metal electrode 11, the transparent source electrode 26a, and the transparent drain electrode 26b, a semiconductor layer formation process for simultaneously forming the first semiconductor layer 12 and the second semiconductor layer 22, an ohmic contact layer formation process for simultaneously forming the first ohmic contact layer 13 and the second ohmic contact layer 23, and a transparent electrode formation process for simultaneously forming the first transparent electrode 16, the transparent source electrode 26a, and the transparent drain electrode 26b.

[0147] This shortens the manufacturing process and makes it possible to manufacture the device in existing thin-film transistor factories.

[0148] (13) In the method for manufacturing the two-dimensional photosensor 100 of (11) or (12), the first semiconductor layer 12 contains amorphous silicon, and the first ohmic contact layer 13 contains n+ amorphous silicon.

[0149] This allows the two-dimensional photosensor 100 to be manufactured using the same manufacturing process as existing amorphous silicon thin-film transistors. No new manufacturing process needs to be added or modified. In conventional photosensors, such as PIN-type amorphous silicon sensors like solar cells, increasing light sensitivity requires thickening the amorphous silicon layer to approximately 1 to 2 microns to enhance light absorption. In contrast, in the Schottky diode disclosed herein, carriers are generated at the "narrow interface" between the metal and semiconductor, eliminating the need to thicken the entire amorphous silicon film. Therefore, high sensitivity can be achieved even with a thin amorphous silicon film of approximately several hundred nanometers, which is commonly used in amorphous silicon thin-film transistor factories.

[0150] (14) In the manufacturing method of the two-dimensional photosensor 100 of (11), the first semiconductor layer 12 includes an amorphous silicon layer, the first ohmic contact layer 13 includes an n+ amorphous silicon layer, the signal readout circuit thin film transistor 121 has a second metal electrode 21 arranged on the glass substrate 1 and functioning as a gate electrode, a second semiconductor layer 22 consisting of an IGZO layer, and a second transparent electrode 26 arranged on the second semiconductor layer 22 and functioning as a source electrode and a drain electrode, and the manufacturing method of the two-dimensional photosensor 100 has a metal electrode film formation process that simultaneously forms the first metal electrode 11 and the second metal electrode 21, and a transparent electrode film formation process that simultaneously forms the first transparent electrode 16 and the second transparent electrode 26.

[0151] This allows high mobility to be achieved over a large area in the signal readout circuit thin film transistor 121. It becomes possible to arrange the readout circuit 120 and the photodiode 110 over the entire surface of the display. [Explanation of symbols]

[0152] 1. Glass substrate 2 scanning electrodes 3. Signal readout electrode 3a Metal source electrode 3b Metal drain electrode 4 Reference voltage section 5 Common electrode 11 First metal electrode 12 First semiconductor layer 13 First ohmic contact layer 14 First insulating layer 15 Fifth insulating layer 16 First transparent electrode 16a Lower first transparent electrode 16b Upper first transparent electrode 17 Second insulating layer 18 Fourth transparent electrode 19 Fourth metal electrode 21 Second metal electrode 21a First gate electrode 21b second gate electrode 22 Second semiconductor layer 23 Second ohmic contact layer 24 Third insulating layer 25 Second Removal Section 26 Second transparent electrode 26a Transparent source electrode 26b Transparent drain electrode 27 Fourth insulating layer 28 Third metal electrode 29 Third transparent electrode 100 Two-dimensional photosensor 110 Photodiode 120 readout circuit 121 Signal readout circuit thin film transistor 130 Gate Driver 140 Multiplexer 150 Signal Processing Circuit 200 Photo-sensing unit L External light C1 First contact C2 Second contact part CE channel etching part RM1 Insulation layer removal section S Schottky barrier Vb Reference voltage

Claims

1. A two-dimensional photosensor, It has a plurality of photodiodes arranged, The photodiode is a first metal electrode; a first semiconductor layer; a first ohmic contact layer; a first transparent electrode; and the first semiconductor layer and the first ohmic contact layer are disposed between the first metal electrode and the first transparent electrode; a Schottky barrier is provided at an interface between the first semiconductor layer and the first metal electrode or at an interface between the first semiconductor layer and the first transparent electrode; sensing light incident from the first transparent electrode side toward the first semiconductor layer; Two-dimensional photosensor.

2. the first semiconductor layer is made of amorphous silicon; the first ohmic contact layer is made of n+ amorphous silicon; The two-dimensional photosensor according to claim 1 .

3. the first metal electrode has a light-shielding property and is configured to be drawn out of a light-sensing region; The two-dimensional photosensor according to claim 1 or 2.

4. The photocurrent of each of the photodiodes is acquired individually through direct connection or scanned and acquired through a simple matrix method. The two-dimensional photosensor according to claim 1 or 2.

5. a readout circuit for reading out a signal from the photodiode; the readout circuit includes a thin film transistor; the thin film transistor has at least one layer that is the same as a layer that constitutes the photodiode; The two-dimensional photosensor according to claim 1 or 2.

6. the thin film transistor has a second metal electrode; the second metal electrode functions as a gate electrode of the thin film transistor; the second metal electrode is made of the same layer as the first metal electrode of the photodiode, and they are not electrically connected to each other; The two-dimensional photosensor according to claim 5 .

7. the thin film transistor has a source electrode and a drain electrode; the source electrode and the drain electrode include at least the same layer as the first transparent electrode or the first metal electrode of the photodiode; The two-dimensional photosensor according to claim 5 .

8. the thin film transistor has a second semiconductor layer; the second semiconductor layer is made of the same layer as the first semiconductor layer of the photodiode; The two-dimensional photosensor according to claim 5 .

9. the thin film transistor has a second semiconductor layer made of indium gallium zinc oxide; The two-dimensional photosensor according to claim 5 .

10. The photodiode has a dielectric layer on the outermost surface opposite to the glass substrate to reduce surface reflection. The two-dimensional photosensor according to claim 1 or 2.

11. A method for manufacturing a two-dimensional photosensor, comprising: Two-dimensional photosensors are The image sensor comprises a plurality of photodiodes arranged in an array and a circuit for reading out signals from the photodiodes, The photodiode is a first metal electrode; a first semiconductor layer; a first ohmic contact layer; a first transparent electrode; and the first semiconductor layer and the first ohmic contact layer are disposed between the first metal electrode and the first transparent electrode; a Schottky barrier is provided at an interface between the first semiconductor layer and the first metal electrode or at an interface between the first semiconductor layer and the first transparent electrode; sensing light incident from the first transparent electrode side toward the first semiconductor layer; the signal readout circuit includes a thin film transistor; a step of simultaneously forming at least one layer constituting the photodiode and the thin film transistor; A method for manufacturing a two-dimensional photosensor.

12. The thin film transistor is a gate electrode; a second semiconductor layer; and a second ohmic contact layer; a source electrode and a drain electrode; and a metal electrode forming step of simultaneously forming the first metal electrode and the gate electrode or a metal electrode forming step of simultaneously forming the first metal electrode, the source electrode, and the drain electrode; a semiconductor layer forming step of simultaneously forming the first semiconductor layer and the second semiconductor layer; an ohmic contact layer forming step of simultaneously forming the first ohmic contact layer and the second ohmic contact layer; a transparent electrode film forming step of simultaneously forming the first transparent electrode, the source electrode, and the drain electrode; The method for manufacturing the two-dimensional photosensor according to claim 11 .

13. the first semiconductor layer comprises amorphous silicon, and the first ohmic contact layer comprises n+ amorphous silicon; The method for manufacturing the two-dimensional photosensor according to claim 11 or 12.

14. the first semiconductor layer includes an amorphous silicon layer; the first ohmic contact layer comprises an n+ amorphous silicon layer; The thin film transistor is a second metal electrode disposed on the glass substrate and functioning as a gate electrode; a second semiconductor layer made of an IGZO layer; a second transparent electrode disposed on the second semiconductor layer and functioning as a source electrode and a drain electrode; a metal electrode forming step of simultaneously forming the first metal electrode and the second metal electrode; a transparent electrode forming step of simultaneously forming the first transparent electrode and the second transparent electrode; The method for manufacturing the two-dimensional photosensor according to claim 11 , comprising:

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