JP6164924B2 - Detection device and detection system - Google Patents

Description

  The present invention relates to a detection apparatus and a detection system applied to a medical image diagnostic apparatus, a nondestructive inspection apparatus, an analysis apparatus using radiation, and the like.

  In recent years, thin-film semiconductor manufacturing technology has been applied to detection devices having an array of pixels (pixel array) in which a switch element such as a TFT (thin film transistor) and a conversion element that converts radiation or light such as a photodiode into a charge are combined. It's being used. As a conventional detection device, Patent Document 1 discloses a switch element disposed on a substrate, a conversion element disposed on the switch element and electrically connected to the switch element, a substrate, the switch element, and the conversion element. And a detection device including an interlayer insulating layer disposed between the two. In addition, the conversion element disclosed in Patent Document 1 includes a pixel electrode electrically connected to the switch element, a counter electrode disposed to face the pixel electrode, and a semiconductor layer disposed between the pixel electrode and the counter electrode. And an impurity semiconductor layer disposed between the pixel electrode and the semiconductor layer. A transparent conductive oxide is used for the pixel electrode in order to improve the efficiency of light irradiation for reducing afterimages. Further, in Patent Document 2, a gap is provided in a pixel electrode in a region where a semiconductor layer is disposed in order to increase the efficiency of light irradiation for reducing afterimages.

JP 2002-026300 A JP 2007-329434 A

  However, in the configuration of Patent Document 1, it is difficult to achieve both the adhesion between the impurity semiconductor layer and the transparent conductive oxide and the dark current characteristics of the conversion element. An attempt to improve the adhesion between the impurity semiconductor layer and the transparent conductive oxide causes a decrease in the dark current characteristics of the conversion element. Conversely, an attempt to improve the dark current characteristics of the conversion element The adhesion between the semiconductor layer and the transparent conductive oxide is reduced. In the configuration of Patent Document 2, the connection resistance between the conversion element and the switch element increases due to the gap between the pixel electrodes, and it may be difficult to ensure a sufficient transfer rate for a frame rate of, for example, 30 fps. Therefore, an object of the present invention is to provide a detection device capable of ensuring good adhesion between an impurity semiconductor layer and a pixel electrode, good dark current characteristics of a conversion element, and good transfer speed.

The detection apparatus of the present invention includes a substrate that can transmit visible light , a pixel electrode, an impurity semiconductor layer, and a semiconductor layer in order from the substrate side , the radiation conversion element that converts radiation or light into electric charges, and the substrate. A light source for irradiating the semiconductor layer with visible light , wherein the pixel electrode includes a metal layer having a gap located in a region overlapping the orthogonal projection of the semiconductor layer, A transistor disposed between the substrate and the pixel electrode; and a wiring electrically connected to the transistor, wherein the wiring includes a gap at a position including an orthogonal projection of the gap. It is characterized by. Further, the detection system of the present invention includes the detection device, a signal processing means for processing a signal from the detection device, a recording means for recording a signal from the signal processing means, and a signal processing means. Display means for displaying a signal, and transmission processing means for transmitting a signal from the signal processing means.

  According to the present invention, it is possible to provide a detection device capable of ensuring good adhesion between an impurity semiconductor layer and a pixel electrode, good dark current characteristics of a conversion element, and good transfer speed.

FIG. 2 is a schematic plan view per pixel of the detection apparatus according to the first embodiment, a schematic plan view of a pixel electrode per pixel, and a schematic cross-sectional view per pixel. It is a plane schematic diagram per pixel of the detection apparatus according to another example of the first embodiment. It is a typical equivalent circuit schematic of a detection apparatus. It is a cross-sectional schematic diagram for demonstrating the structure of a detection apparatus. It is the plane schematic diagram and cross-sectional schematic diagram per pixel of the detection apparatus which concerns on 2nd Embodiment. It is a plane schematic diagram per pixel of the detection device according to the third embodiment. It is a plane schematic diagram per pixel of the detection device according to the fourth embodiment. It is a plane schematic diagram per pixel of the detection device according to the fifth embodiment. It is a conceptual diagram of the radiation detection system using the detection apparatus of this invention.

  Hereinafter, embodiments of the present invention will be specifically described with reference to the accompanying drawings. In this specification, in addition to α-rays, β-rays, γ-rays, etc., which are beams produced by particles (including photons) emitted by radioactive decay, beams having the same or higher energy, such as X-rays, Particle rays and cosmic rays are also included in the radiation.

(First embodiment)
First, the detection apparatus according to the first embodiment will be described with reference to FIGS. 1 (a) to 1 (c). 1A is a schematic plan view of one pixel constituting the detection device, FIG. 1B is a schematic plan view of pixel electrodes per pixel, and FIG. 1C is a schematic diagram of FIG. It is a cross-sectional schematic diagram in AA '. Note that in FIG. 1A, each insulating layer, covering member, semiconductor layer, and each impurity semiconductor layer, which will be described later, are omitted for simplification.

  In the detection device of the present invention, a plurality of pixels 11 are arranged in a matrix on a substrate 100. As shown in FIGS. 1A to 1C, one pixel 11 is a conversion element 12 that converts radiation or light into electric charge, and a switch element that outputs an electric signal corresponding to the electric charge of the conversion element 12. TFT (thin film transistor) 13. In this embodiment, an amorphous silicon PIN photodiode is used as the conversion element 12. The conversion element 12 is disposed on a TFT 13 provided on an insulating substrate 100 such as a glass substrate, with an interlayer insulating layer 120 made of an organic material interposed therebetween. The interlayer insulating layer 120 is disposed so as to cover the plurality of TFTs 13 which are a plurality of switch elements. As shown in FIG. 1C, the surface of the interlayer insulating layer 120 is covered with a covering member 121 and a pixel electrode 122 made of an inorganic material.

  The TFT 13 includes a control electrode 131, an insulating layer 132, a semiconductor layer 133, an impurity semiconductor layer 134 having an impurity concentration higher than that of the semiconductor layer 133, and a first main layer, which are arranged on the substrate 100 in order from the substrate side. An electrode 135 and a second main electrode 136 are included. The impurity semiconductor layer 134 is in contact with the first main electrode 135 and the second main electrode 136 in a partial region thereof, and a region between the regions of the semiconductor layer 133 in contact with the partial region is a channel region of the TFT. The control electrode 131 is electrically connected to the control wiring 15, the first main electrode 135 is electrically connected to the signal wiring 16, and the second main electrode 136 is electrically connected to the pixel electrode 122 of the conversion element 12. It is connected to the. In the present embodiment, the first main electrode 135, the second main electrode 136, and the signal wiring 16 are integrally formed of the same conductive layer, and the first main electrode 135 constitutes a part of the signal wiring 16. ing. The protective layer 137 is provided so as to cover the TFT 13, the control wiring 15, and the signal wiring 16. In this embodiment, an inverted stagger type TFT using the semiconductor layer 133 and the impurity semiconductor layer 134, which are mainly made of amorphous silicon, is used as the switch element. However, the present invention is not limited to this. For example, a staggered TFT mainly composed of polycrystalline silicon, an organic TFT, an oxide TFT, or the like can be used. In the present embodiment, the control electrode 131 and the control wiring 15 are integrally formed using the same conductive layer. The first main electrode 135 and the signal wiring 16 are integrally formed using the same conductive layer.

  The interlayer insulating layer 120 is disposed between the substrate 100 and a pixel electrode 122 of the conversion element 12 described later so as to cover the plurality of TFTs 13 and has a contact hole. The pixel electrode 122 of the conversion element 12 and the second main electrode 136 of the TFT 13 are electrically connected in a contact hole provided in the interlayer insulating layer 120.

The conversion element 12 is disposed on the interlayer insulating layer 120 in this order from the interlayer insulating layer side (substrate side), the metal layer 122 serving as the pixel electrode, the first conductivity type impurity semiconductor layer 123, and the semiconductor layer 124. A second conductivity type impurity semiconductor layer 125, and a counter electrode 126. The pixel electrode includes a metal layer 122 made of a metal material or an alloy material. As the metal material, Al (2.655 × 10 ⁻⁶ Ωcm), Mo (5.0 × 10 ⁻⁸ Ωcm), Cr (1.29 × 10 ⁻⁵ Ωcm), Ti (4.2 × 10 ⁻⁵⁾ Ωcm), W (5.65 × 10 ⁻⁶ Ωcm), Cu (1.67 × 10 ⁻⁶ Ωcm) can be suitably selected. As the alloy material, an Al-based alloy is preferably used, and for example, Al—Nd (5.0 × 10 ⁻⁸ Ωcm) can be preferably used. Such a metal material or alloy material has higher plasma resistance in plasma CVD when forming the first conductivity type impurity semiconductor layer 123 than a transparent conductive oxide as in Patent Document 1. Therefore, the metal layer 122 is less damaged by plasma CVD than the transparent conductive oxide layer, and has higher adhesion to the first conductive type impurity semiconductor layer 123 than the transparent conductive oxide layer. be able to. Further, since the metal layer 122 has better surface flatness than the transparent conductive oxide, the lattice defects of the impurity semiconductor layer 123 in contact with the metal layer 122 are larger than those in the impurity semiconductor layer in contact with the transparent conductive oxide. Can be less. Therefore, the impurity semiconductor layer 123 in contact with the metal layer 122 can have a higher impurity concentration than the impurity semiconductor layer in contact with the transparent conductive oxide, and the reverse saturation current at the time of reverse bias of the PIN photodiode, that is, Dark current can be suppressed. However, the metal layer 122 sufficiently supplies visible light emitted from a light source (not shown) that can be provided on the surface side of the substrate 100 opposite to the surface on which the pixels 11 are disposed to reduce afterimages to the semiconductor layer 124. It is difficult to transmit. Therefore, the metal layer 122 includes a gap 122 ′ located in a region overlapping with the orthogonal projection of the semiconductor layer 124. Here, the orthographic projection of the semiconductor layer 124 is an orthogonal projection from the semiconductor layer 124 to the metal layer 122. Since the metal layer 122 includes the gap 122 ′, the semiconductor layer 124 can be sufficiently irradiated with light from a light source (not shown) through the gap 122 ′. Further, since the specific resistance of the metal material or alloy material is lower than that of the transparent conductive oxide (˜2.0 × 10 ⁻⁴ Ωcm), the resistance of the metal layer 122 can be used as a pixel electrode even if the gap 122 ′ is provided. It becomes easy to suppress it to be sufficiently low to be usable. Therefore, it becomes easy to ensure a sufficient pixel transfer rate. As described above, by using the metal layer 122 having the gap 122 ′ in the region where the semiconductor layer 124 is disposed, good adhesion between the impurity semiconductor layer and the pixel electrode, good dark current characteristics of the conversion element, and It is possible to provide a detection device capable of ensuring a good transfer rate. The first conductivity type impurity semiconductor layer 123 has a polarity of the first conductivity type, and has a higher concentration of the first conductivity type impurity than the semiconductor layer 124 and the second conductivity type impurity semiconductor layer 125. The second conductivity type impurity semiconductor layer 125 has a second conductivity type polarity and has a higher concentration of second conductivity type impurities than the first conductivity type impurity semiconductor layer 123 and the semiconductor layer 124. This corresponds to another impurity semiconductor layer of the present invention. The first conductivity type and the second conductivity type are conductivity types having different polarities, and in this embodiment, the first conductivity type is n-type and the second conductivity type is p-type. However, the present invention is not limited thereto, and the first conductivity type may be p-type and the second conductivity type may be n-type. An electrode wiring (not shown) is electrically connected to the counter electrode 126 of the conversion element 12. The metal layer 122 serving as a pixel electrode is electrically connected to the second main electrode 136 of the TFT 13 through a contact hole provided in the interlayer insulating layer 120. In the present embodiment, a photodiode using a first conductivity type impurity semiconductor layer 123, a semiconductor layer 124, and a second conductivity type impurity semiconductor layer 125 mainly containing amorphous silicon is used. In the present embodiment, the surface of the interlayer insulating layer 120 is covered with the metal layer 122 and the covering member 121 made of an inorganic material. That is, the covering member 121 is disposed between the interlayer insulating layer 120 and the impurity semiconductor layer 123 in the gap 122 ′ of the metal layer 122 and between the pixel electrodes of the adjacent pixels 11. Therefore, exposure of the surface of the interlayer insulating layer 120 is suppressed when an impurity semiconductor film to be the impurity semiconductor layer 123 is formed by a CVD method, an evaporation method, a sputtering method, or the like. Therefore, mixing of the organic material into the impurity semiconductor layer 123 can be reduced. In this embodiment, the impurity semiconductor layer 123, the semiconductor layer 124, and the impurity semiconductor layer 125 are separated or removed for each pixel on the covering member 121. At the time of separation or removal, the covering member 121 serves as an etching stopper layer. Therefore, it is possible to suppress contamination of the conversion element by the organic material without exposing the interlayer insulating layer 120 to the dry etching species. In FIG. 1C, the covering member 121 is disposed between the interlayer insulating layer 120, the metal layer 122, and the impurity semiconductor layer 123, but the metal layer 122, the impurity semiconductor layer 123, the interlayer insulating layer 120, and the like. It may be arranged between.

  A passivation layer 127 is provided so as to cover the conversion element 12 and the covering member 121.

  In the present embodiment, the photodiode using the first conductivity type impurity semiconductor layer 123, the semiconductor layer 124, and the second conductivity type impurity semiconductor layer 125, which is mainly made of amorphous silicon, is used. The invention is not limited to this. For example, an element that directly converts radiation into electric charges using the first conductive type impurity semiconductor total 123, the semiconductor layer 124, and the second conductive type impurity semiconductor layer 125 mainly containing amorphous selenium can be used. . The counter electrode 126 is disposed to face the metal layer 122 serving as a pixel electrode, and is electrically connected to an electrode wiring (not shown). When a photodiode using the first conductive type impurity semiconductor layer 123, the semiconductor layer 124, and the second conductive type impurity semiconductor layer 125, which is mainly made of amorphous silicon, is used, the counter electrode 126 is formed of a transparent conductive oxide. Is preferably used. This is because light from a scintillator (not shown) that converts the wavelength of radiation into visible light can be transmitted to the semiconductor layer 124 satisfactorily.

  In the present embodiment, the metal layer 122 is provided with a plurality of square gaps 122 ′ in a two-dimensional array except for the region located in the contact hole. Providing the gap 122 ′ in the region located in the contact hole of the metal layer 122 is not preferable because it causes an increase in connection resistance between the conversion element 12 and the transistor 13 and a connection failure. However, the shape of the gap 122 ′ of the present invention is not limited thereto, and various shapes of the gap 122 ′ can be provided. For example, a rectangular gap 122 ′ whose long side is parallel to the signal wiring 16 as shown in FIG. 2A, or a rectangular gap whose long side is parallel to the control wiring 15 as shown in FIG. A plurality of 122 ′ may be provided in the metal layer 122. Further, as shown in FIG. 2C, the metal layer 122 has a polygonal gap 122 ′, a rectangular gap 122 ′, and a square gap 122 ′ in combination. A plurality of radials may be provided around the center. In the embodiment described with reference to FIGS. 1A and 2A to 2C, the covering member 121 corresponding to the gap 122 'can be provided in accordance with the shape of the gap 122'. For the gap 122 ′ in FIG. 1A, a plurality of covering members 121 are provided in a square shape, and for the gap 122 ′ in FIG. A plurality of rectangular shapes parallel to each other. Further, for the gap 122 ′ in FIG. 2B, the covering member 121 is provided with a plurality of rectangular shapes whose long sides are parallel to the control wiring 15. 2C, a polygonal covering member 121, a rectangular covering member 121, and a square covering member 121 are provided corresponding to the gaps 122 '. In addition, although the metal layer 122 is described as a single layer in FIG. 1C, the present invention is not limited thereto, and a plurality of layers of different materials may be used.

  Next, a schematic equivalent circuit of the detection apparatus according to the first embodiment of the present invention will be described with reference to FIG. In FIG. 3, an equivalent circuit diagram of 3 rows and 3 columns is used for simplification of the description. However, the present invention is not limited to this, and the detection apparatus has n rows and m columns (n and m are both 2). A natural number) pixel array. In the detection apparatus according to this embodiment, a conversion unit 3 including a plurality of pixels 1 arranged in the row direction and the column direction is provided on the surface of the substrate 100. Each pixel 1 includes a conversion element 12 that converts radiation or light into an electric charge, and a TFT 13 that outputs an electric signal corresponding to the electric charge of the conversion element 12. A scintillator (not shown) that converts the wavelength of radiation into visible light may be disposed on the surface of the conversion element on the counter electrode 126 side. The electrode wiring 14 is commonly connected to the counter electrodes 126 of the plurality of conversion elements 12 arranged in the column direction. The control wiring 15 is commonly connected to the control electrodes 131 of the plurality of TFTs 13 arranged in the row direction, and is electrically connected to the drive circuit 2. The drive circuit 2 supplies drive pulses sequentially or simultaneously to a plurality of control wirings 15 arranged in the column direction, so that electric signals from the pixels are parallel to the plurality of signal wirings 16 arranged in the row direction. Is output. The signal wiring 16 is connected in common to the first main electrodes 135 of the plurality of TFTs 13 arranged in the column direction, and is electrically connected to the readout circuit 4. The readout circuit 4 includes, for each signal wiring 16, an integration amplifier 5 that integrates and amplifies the electrical signal from the signal wiring 16, and a sample hold circuit 6 that samples and holds the electrical signal amplified and output by the integration amplifier 5. Prepare. The readout circuit 4 further includes a multiplexer 7 that converts electrical signals output in parallel from the plurality of sample and hold circuits 6 into serial electrical signals, and an A / D converter 8 that converts the output electrical signals into digital data. Including. A reference potential Vref is supplied from the power supply circuit 9 to the non-inverting input terminal of the integrating amplifier 5. The power supply circuit 9 is further electrically connected to a plurality of electrode wirings 14 arranged in the row direction, and supplies a bias potential Vs to the counter electrode 126 of the conversion element 12.

  Below, operation | movement of the detection apparatus of this embodiment is demonstrated. A reference potential Vref is applied to the pixel electrode 122 of the conversion element 12 via the TFT 13, and a bias potential Vs necessary for electron-hole pair separation generated by radiation or visible light is applied to the counter electrode 126. In this state, radiation that has passed through the subject or visible light corresponding thereto enters the conversion element 12, is converted into electric charge, and is accumulated in the conversion element 12. The electrical signal corresponding to the electric charge is output in parallel to each signal line 16 in units of rows by the TFT 13 being turned on in units of rows by a drive pulse applied from the drive circuit 2 to the control line 15. The electric signal output in units of rows is read out to the outside as digital data for one row by the reading circuit 4. By sequentially performing this operation in units of rows, an image signal for one image is output from the pixels to the readout circuit 4, and image data that is digital data for one image is output from the readout circuit 4. The In order to perform such an operation, even if the pixel electrode of the present invention includes the metal layer 122 having the gap 122 ′, a sufficient image signal must be output from the plurality of pixels 11. Therefore, in this invention, it is preferable that it is a pixel electrode which satisfy | fills the following formula | equation (1).

R _S ≦ T / (n × C _S ) −R _ON (1)
Here, _{C S} is the capacitance of the conversion element _12, rows TFT13 driving circuit 2 a plurality of pixels 11 for _{R ON} is for outputting an image signal satisfying the on-resistance, T S / N ratio is required of TFT13 This is the time required to drive sequentially in units. Further, n is the number of rows of the plurality of pixels 11, and _RS is the resistance of a member made up of the impurity semiconductor layer 123 and the pixel electrode. Here, the required S / N ratio is the difference between the amount of charge that can be generated by the conversion element 12 and the amount of charge that can be transferred by the conduction of the TFT 13, that is, the amount of charge remaining in the pixel 11. 12 is the reciprocal of the value divided by the amount of charge that can be generated. Incidentally, in the embodiment shown in FIG. 1 (c), the sheet resistance of the impurity semiconductor layer 123 is preferably equal to or less than 200 times the on-resistance _{R ON} of the TFT 13.

  Next, the configuration of the detection apparatus of the present invention will be described with reference to FIGS. 4 (a) and 4 (b). The detection apparatus illustrated in FIG. 4A includes a pixel 11 and a scintillator 21 in order from the substrate 100 side on the radiation incident side of the substrate 100. In addition, the detection apparatus includes a light source 24 and a circuit board 23 in order from the substrate 100 side on the side opposite to the side where the pixels of the substrate 100 are provided. The light source 24 is for irradiating the semiconductor layer 124 of the conversion element 12 of the pixel 11 with visible light through the gap 122 ′ between the substrate 100 and the metal layer 122 in order to reduce an afterimage. The circuit board 23 is provided with the drive circuit 2 or the readout circuit 4 and is electrically connected to a flexible printed board electrically connected to the pixel 11. The circuit board 23 includes at least one of an integrated circuit that supplies a control signal to the drive circuit 2 and an integrated circuit that processes an image signal from the readout circuit 4. On the other hand, the detection apparatus shown in FIG. 4B includes a pixel 11, a scintillator 21, and a circuit board 23 in order from the substrate 100 side on the side opposite to the radiation incident side of the substrate 100. The circuit board 23 is provided on the radiation incident side of the substrate 100, that is, on the side opposite to the side on which the pixels of the substrate 100 are provided. 4A and 4B includes a housing 100 that houses a substrate 100, a pixel 11, a scintillator 21, a flexible printed circuit board 22, a circuit board 23, and a light source 24.

(Second Embodiment)
Next, a detection apparatus according to the second embodiment will be described with reference to FIGS. 5 (a) and 5 (b). FIG. 5A is a schematic plan view of one pixel constituting the detection device, and FIG. 5B is a schematic cross-sectional view taken along the line BB ′ of FIG. In FIG. 5A, each insulating layer, covering member, semiconductor layer, and each impurity semiconductor layer are omitted for simplification. The second embodiment shown in FIGS. 5A and 5B is different from the first embodiment shown in FIGS. 1A and 1C in the following points.

  First, the first difference is the position where the gap 122 'is provided. In the second embodiment, the gap 122 ′ is provided in the metal layer 122 so that the orthogonal projection of the gap 122 ′ does not overlap with at least one of the control wiring 15 and the signal wiring 16. Here, the orthogonal projection of the gap 122 ′ is an orthogonal projection from the gap 122 ′ to at least one of the control wiring 15 and the signal wiring 16. When the potential of the control wiring 15 fluctuates due to the drive pulse supplied to the control wiring 15, if the control wiring 15 and the gap 122 'face each other, the potential of the impurity semiconductor layer 123 is affected. When the signal wiring 16 and the gap 122 ′ are opposed to each other, when the potential of the signal wiring 16 varies due to an electric signal output from a certain pixel 11, the impurity semiconductor layer 123 of the conversion element 12 of another pixel 11. Affects the potential. Since the specific resistance of the impurity semiconductor layer 123 is higher than that of the metal layer 122, the time during which the fluctuation of the potential of the impurity semiconductor layer 123 due to the fluctuation of the potential of the wiring converges is longer than that of the metal layer 122. This may cause artifacts in the obtained image signal due to the influence of the fluctuation of the potential of the wiring. In order to suppress the artifact, it is desirable that the metal layer 122 is present in a region facing the wiring of the conversion element 12. Therefore, the gap 122 ′ is provided in the metal layer 122 so that the orthogonal projection of the gap 122 ′ does not overlap with at least one of the control wiring 15 and the signal wiring 16. It is also desirable that the gap 122 ′ is provided in the metal layer 122 so that the orthogonal projection of the gap 122 ′ does not overlap with the transistor 13.

  The second difference is that, as shown in FIG. 5B, the semiconductor layer 124 and the impurity semiconductor layer 125 are not separated for each pixel 11. Therefore, the area where the semiconductor layer 124 and the impurity semiconductor layer 125 are disposed is larger than that in FIG. 1C, and the aperture ratio is improved as compared with FIG. In FIG. 5B, the counter electrode 126 may be divided for each pixel 11. However, it is preferable that the counter electrode 126 is not separated for each pixel 11 in terms of improving the aperture ratio. This second difference can be suitably applied to other embodiments of the present invention.

(Third embodiment)
Next, a detection apparatus according to the third embodiment will be described with reference to FIG. FIG. 6 is a schematic plan view of one pixel constituting the detection device. In FIG. 6, each insulating layer, covering member, semiconductor layer, and each impurity semiconductor layer are omitted for simplification. The third embodiment shown in FIG. 6 differs from the first embodiment shown in FIG. 1A in the following points.

  In the third embodiment, the control wiring 15 and the signal wiring 16, which are wirings electrically connected to the transistor 13, are provided with a gap 17 at a position including the orthogonal projection of the gap 122 '. This is to suppress artifacts due to fluctuations in the potential of the wiring described in the second embodiment. By not providing the conductive layer of the wiring at a position facing the gap 122 ′, in other words, by providing the gap 17 in the wiring, fluctuations in the potential of the impurity semiconductor layer 123 are suppressed, and artifacts due to fluctuations in the wiring potential are caused. Is suppressed.

(Fourth embodiment)
Next, a detection apparatus according to a fourth embodiment will be described with reference to FIGS. 7 (a) and 7 (b). FIG. 7A is a schematic plan view of one pixel constituting the detection device, and FIG. 7B is a schematic cross-sectional view taken along CC ′ in FIG. In FIG. 7A, each insulating layer, covering member, semiconductor layer, and each impurity semiconductor layer are omitted for simplification. The fourth embodiment shown in FIGS. 7 (a) and 7 (b) differs from the first embodiment shown in FIGS. 1 (a) and 1 (c) in the following points.

  In the fourth embodiment, a conductive layer 128 having a specific resistance lower than that of the impurity semiconductor layer 123 is disposed between the metal layer 122 and the interlayer insulating layer 120, and the pixel electrode includes the metal layer 122 and the conductive layer 128. It is a configuration that includes. The conductive layer 128 has higher light transmittance than the metal layer 122, is in contact with the metal layer 122, and is in contact with the impurity semiconductor layer 123 in the gap 122 '. This is to suppress artifacts due to fluctuations in the potential of the wiring described in the second embodiment. Since the conductive layer 128 is provided between the impurity semiconductor layer 123 and the wiring in the gap 122 ′, the influence on the conversion element due to fluctuations in the potential of the wiring is greater than when the impurity semiconductor layer 123 and the wiring face each other. Is suppressed. However, since the light transmittance from the metal layer 122 needs to be higher than that of the metal layer 122 in order to sufficiently irradiate the semiconductor layer 124 with light from the light source 24, the conductive layer 128 is preferably made of a transparent conductive oxide. The transparent conductive oxide does not have good adhesion to the impurity semiconductor layer 123, but contacts the impurity semiconductor layer 123 only in the gap 122 '. Therefore, the metal layer 122 having good adhesion with the impurity semiconductor layer 123 can ensure sufficient adhesion as the pixel electrode. Moreover, since the sheet resistance of the pixel electrode can be lowered as compared with the first embodiment by such a configuration, the area of the gap 122 can be increased as compared with the first embodiment. Thereby, it is possible to increase the transmittance of light emitted from the light source as compared with the first embodiment, and the afterimage can be further suppressed as compared with the first embodiment.

(Fifth embodiment)
Next, a detection apparatus according to the fifth embodiment will be described with reference to FIGS. 8A and 8B. FIG. 8A is a schematic plan view of one pixel constituting the detection device, and FIG. 8B is a schematic cross-sectional view taken along CC ′ in FIG. 8A. In FIG. 8A, each insulating layer, covering member, semiconductor layer, and each impurity semiconductor layer are omitted for simplification. The fifth embodiment shown in FIGS. 8A and 8B is different from the fourth embodiment shown in FIGS. 7A and 7C in the following points.

In the fifth embodiment, a conductive layer 129 having a specific resistance lower than that of the impurity semiconductor layer 123 is disposed between the metal layer 122 and the impurity semiconductor layer 123, and the pixel electrode includes the metal layer 122 and the conductive layer 129. It is a configuration that includes. The conductive layer 129 has higher visible light transmittance than the metal layer 122, is in contact with the metal layer 122, and is in contact with the impurity semiconductor layer 123 at least in the gap 122 ′. In this structure, since the adhesion between the impurity semiconductor layer 123 and the pixel electrode is determined by the adhesion between the impurity semiconductor layer 123 and the conductive layer 129, the conductive layer 129 has a higher adhesion to the impurity semiconductor layer than the transparent conductive oxide. It is desirable to use higher metal materials or alloy materials. The visible light transmittance of the conductive layer 129 is higher than that of the metal layer 122 and is preferably 10% or more. As a result of sincerity examination, if the following relationship is satisfied, the transmittance of the conductive layer 129 necessary for suppressing the afterimage can be obtained. In order to suppress the afterimage, it is necessary to saturate the conversion element 12 by light irradiation. The saturation charge amount N ₁ of the conversion element 12 is represented by the following formula (2).

N ₁ = (ε ₀ * ε _r * S * V) / (q * d) (2)
Here, S (cm ² ) is the area of the semiconductor layer 124, d is the thickness of the semiconductor layer 124, ε _r (F cm ⁻¹ ) is the relative dielectric constant of the semiconductor layer 124, and ε ₀ (Fcm ⁻¹ ) is a vacuum. , V (v) is the voltage of the conversion element 12, and q (c) is an elementary charge. On the other hand, the photocarrier N2 generated in the conversion element 12 by irradiation with visible light from the light source 24 shown in FIGS. 4A and 4B is expressed by the following equation (3).

N ₂ = T _s * T _a * T _c * T _i * η * P * t * S _o (3)
Here, T _s is the transmittance of the substrate 100 for visible light emitted from the light source 24, T _a is the transmittance of the component between the conversion element 12 and the substrate 100, T _c is the transmittance of the conductive layer 129, and T _i. Is the transmittance of the impurity semiconductor layer 123. Further, η is the internal quantum efficiency of the semiconductor layer 124, P is the photon flux (pieces · cm ⁻² · S ⁻¹ ), t (s) is the irradiation time of visible light, and S ₀ (cm ² ) is the gap 122. Area.

That the conversion element 12 is saturated by light irradiation satisfies N2 ≧ N1. Therefore, it is desirable that the transmittance T _c of the conductive layer 129 satisfies the following formula (4) based on the formula (2) and the formula (3).

T _c ≧ (ε ₀ * ε _r * S * V) / (d * q * T _s * T _a * T _i * η * P * t * S _o ) (4)
The photon flux P is the peak wavelength λ (nm) of visible light emitted from the light source 24, the illuminance E (lx), the maximum luminous sensitivity Km (lmW ⁻¹ ), the relative luminous sensitivity F at the wavelength λ, and the Planck constant h (Js) and the speed of light c (ms ⁻¹ ) can be derived by the following equation (5).

P = E * λ / (Km * F * h * c) (5)
From Equation (4) and Equation (5), T _c ≧ (ε ₀ * ε _r * S * V * Km * F * h * c) / (d * q * T _s * T _a * T _i * η * t * S _o * E * λ) (6)
With such a configuration, the adhesion between the impurity semiconductor layer 123 and the pixel electrode is higher than in the first to fourth embodiments. Further, since the sheet resistance of the pixel electrode can be made lower than that in the first embodiment, the area of the gap 122 can be made larger than that in the first embodiment. Thereby, it is possible to increase the transmittance of light emitted from the light source as compared with the first embodiment, and the afterimage can be further suppressed as compared with the first embodiment. Note that the conductive layer 129 is preferably an alloy containing Mo or Mo or an alloy containing Al or Al, which is light-transmissive when formed into a thin film and can be processed by dry etching.

(Application embodiment)
Next, a radiation detection system using the detection apparatus of the present invention will be described with reference to FIG.

  X-rays 6060 emitted from the X-ray tube 6050 serving as a radiation source pass through the chest 6062 of the patient or subject 6061 and enter each conversion element included in the detection device 6040 of the present invention. This incident X-ray includes information inside the body of the patient 6061. Corresponding to the incidence of X-rays, the conversion unit 3 converts the radiation into electric charges to obtain electrical information. This information is converted into digital data, image-processed by an image processor 6070 as a signal processing means, and can be observed on a display 6080 as a display means in a control room.

  Further, this information can be transferred to a remote place by transmission processing means such as a telephone line 6090, and can be displayed on a display 6081 serving as a display means such as a doctor room in another place or stored in a recording means such as an optical disk. It is also possible for a doctor to make a diagnosis. Moreover, it can also record on the film 6110 used as a recording medium by the film processor 6100 used as a recording means.

DESCRIPTION OF SYMBOLS 11 Pixel 12 Conversion element 13 Switch element 14 Electrode wiring 15 Control wiring 16 Signal wiring 100 Substrate 120 Interlayer insulation layer 121 Covering member 122 Metal layer 122 ′ gap 123 First conductivity type impurity semiconductor layer 124 Semiconductor layer 125 Second conductivity type Impurity semiconductor layer 126 Counter electrode

Claims (12)

A substrate capable of transmitting visible light;
A conversion element for converting radiation or light into an electric charge and a sequentially pixel electrode and the impurity semiconductor layer and the semiconductor layer from the substrate side,
A light source for transmitting visible light to the semiconductor layer through the substrate;
A detection device comprising:
The pixel electrode includes a metal layer having a gap located in a region overlapping with an orthogonal projection of the semiconductor layer,
A transistor disposed between the substrate and the pixel electrode; and a wiring electrically connected to the transistor;
The wiring device is provided with a gap at a position including an orthogonal projection of the gap . Each, and said conversion element, said being electrically connected to the pixel electrode wherein the said transistor for transferring the charge, a plurality of pixels arranged in a matrix on the substrate,
A drive circuit for sequentially driving the transistors of the plurality of pixels in units of rows in order to output image signals based on the charges from the plurality of pixels;
Including
The drive circuit sequentially drives the transistors of the plurality of pixels row by row in order to output the image signal satisfying the required S / N ratio, with CS as the capacitance of the conversion element, RON as the transistor. T is the time required for this, n is the number of rows of the plurality of pixels, and RS is the resistance of the member made of the impurity semiconductor layer and the pixel electrode
RS ≦ T / (n × CS) -RON
The detection device according to claim 1, wherein: An interlayer insulating layer is disposed between the substrate and the transistor and the pixel electrode,
The interlayer insulating layer is provided with a contact hole for electrically connecting the pixel electrode and the transistor,
The detection device according to claim 2, wherein the transistor and the pixel electrode are electrically connected in the contact hole. The pixel electrode further includes a conductive layer disposed between the metal layer and the impurity semiconductor layer,
The conductive layer is made of a metal material or an alloy material, has a light transmittance higher than that of the metal layer, is in contact with the metal layer, and is in contact with the impurity semiconductor layer in the gap. The detection device according to claim 3. The pixel electrode further includes a conductive layer disposed between the metal layer and the interlayer insulating layer,
The detection device according to claim 3, wherein the conductive layer has higher light transmittance than the metal layer, is in contact with the metal layer, and is in contact with the impurity semiconductor layer in the gap. The detection device according to claim 5 , wherein the conductive layer is made of a transparent conductive oxide. Detection device according to any one of claims 3-6, characterized by further having arranged the covering member to the surface of the interlayer insulating layer to cover the pixel electrode. Gap between the metal layer, the detection device according to any one of claims 3-7, characterized in that provided except an area located in the contact hole. The semiconductor layer is made of amorphous silicon, the detection device according to any one of claims 1 to 8 wherein the impurity semiconductor layer, characterized in that an n-type amorphous silicon. The conversion element includes: a counter electrode disposed to face the pixel electrode; and another impurity semiconductor layer made of p-type amorphous silicon disposed between the semiconductor layer and the counter electrode. The detection device according to claim 9 , further comprising: The detection device according to any one of claims 1 to 10 ,
Signal processing means for processing a signal from the detection device;
Recording means for recording a signal from the signal processing means;
Display means for displaying a signal from the signal processing means;
Transmission processing means for transmitting a signal from the signal processing means;
A detection system comprising: The detection system according to claim 11 , further comprising a radiation source that emits radiation toward the detection device.

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