JP6282363B2 - Detection device and detection system - Google Patents

Description

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

  Thin film semiconductor manufacturing technology is also used for detection devices such as light detection devices and radiation detection devices having an array of pixels (pixel array) in which switch elements such as TFTs (thin film transistors) and conversion elements such as photoelectric conversion elements are combined. ing. In recent years, in particular, in response to the demand for higher speed and higher sensitivity of the device, a detection device having a pixel array using a polycrystalline semiconductor TFT as a switch element has been studied. In general, the pixel structure of the detection device is classified into two types: a planar type in which the conversion element and the switch element are arranged on the same plane, and a stacked type in which the conversion element is arranged above the switch element. In the planar type, since the conversion element and the switch element can be formed by the same semiconductor manufacturing process, the manufacturing process can be simplified. On the other hand, in the stacked type detection device, since the conversion element is arranged above the switch element, the area of the conversion element in one pixel can be formed larger than that of the flat type to achieve a high aperture ratio. For this reason, the stacked detection device can obtain a larger signal, and the use efficiency of radiation or light is higher than that of the planar detection device, and a high S / N ratio can be obtained. .

  In such a detection apparatus, in Patent Document 1, in a photoelectric conversion apparatus having a pixel provided with a photoelectric conversion element on a switch element on a substrate, in order to increase the amount of light (dose) that the pixel can receive, A photoelectric conversion device capable of increasing the capacity is disclosed. More specifically, Patent Document 1 discloses a photoelectric conversion device including a capacitor element directly connected to a photoelectric conversion element in a region overlapping with the photoelectric conversion element in a plane. In the apparatus disclosed in Patent Document 1 described above, since the capacitance element is directly connected to the photoelectric conversion element, the capacitance value of the pixel is fixed, and thus the capacitance value of the pixel cannot be adjusted. In particular, a detection device for radiography used for medical image diagnosis requires a detection device that can perform both general imaging (still image shooting) and fluoroscopic imaging (moving image shooting). In fluoroscopic imaging, since one image is captured with a radiation dose of about 1/100 of that in general imaging, the maximum value of the radiation dose required for pixels differs greatly between fluoroscopic imaging and general imaging. For example, when fluoroscopy is performed with the capacity value of a pixel that allows the dose of radiation required for still image capture, the pixel capacity value is too large for the dose of fluoroscopy radiation. There is a fear that you can not get. On the other hand, when general imaging is performed with the capacity value of a pixel that allows the radiation dose required for fluoroscopic imaging, the pixel capacity value is too small for the radiation dose of general imaging, so the pixel is saturated. Therefore, there is a possibility that a necessary signal cannot be obtained.

  On the other hand, Patent Document 2 discloses a detection device that connects a capacitor to a conversion element via a switch and controls the capacitance value of the conversion element by controlling the switch.

JP 2008-085029 A JP 2002-344809 A

  An object of the present invention is to provide a detection device that can adjust the capacitance value of a pixel and obtain a high S / N ratio.

The detection device of the present invention includes a transistor disposed on a substrate, a conversion element disposed on the transistor and connected to the transistor, a semiconductor layer connected to the conversion element, and an insulating layer. A semiconductor portion disposed between the substrate and the conversion element, wherein the semiconductor layer is located in a region corresponding to an orthogonal projection of the conductor portion. parts and the conversion element and the ohmic contact portion for establishing an ohmic contact with the semiconductor portion, and a capacitive element having said transducer the capacitive element is accumulated carriers in the semiconductor portion to the transistor and the first potential to be connected in parallel, a detection device including a selectively supplying potential supply means and a second potential different from the first potential, to the conductor portion, the Omikkukon And the second potential is depleted of the semiconductor part and does not function as an electrode of the capacitor element. The second part is located outside the region and connected to the conversion element and the semiconductor part. Thus, the capacitor element has a potential that does not allow the capacitor to be connected in parallel with the conversion element .

  According to the present invention, it is possible to provide a detection device capable of adjusting the capacitance value of a pixel and obtaining a high S / N ratio.

1 is an equivalent circuit diagram of a detection device according to a first embodiment of the present invention. It is the top view and sectional drawing of 1 pixel of the detection apparatus which concern on the 1st Embodiment of this invention. It is the top view and sectional drawing of 1 pixel of the detection apparatus which concern on the other example of the 1st Embodiment of this invention. It is an equivalent circuit schematic of the detection apparatus which concerns on the 2nd Embodiment of this invention. It is a top view of 1 pixel of a detecting device concerning a 2nd embodiment of the present invention. It is sectional drawing of 1 pixel of the detection apparatus which concerns on the 2nd Embodiment of this invention. It is the top view and sectional drawing of 1 pixel of the detection apparatus which concern on the other example of the 2nd Embodiment of this invention. It is the top view and sectional drawing of 1 pixel of the detection apparatus which concern on the 3rd Embodiment of this invention. It is the top view and sectional drawing of 1 pixel of the detection apparatus which concern on the other example of the 3rd Embodiment of this invention. It is the conceptual diagram which showed the example of application to the X-ray detection system of the detection apparatus which concerns on this invention.

  Hereinafter, embodiments of the present invention will be specifically described with reference to the accompanying drawings. In addition, in this specification, radiation is a beam having energy of the same degree or more, for example, X-rays, β-rays, γ-rays, etc., which are beams formed by particles (including photons) emitted by radiation decay, It also includes rays, particle rays, cosmic rays, etc.

(First embodiment)
First, the detection apparatus according to this embodiment will be described with reference to FIGS. 1 (a) and 1 (b). FIG. 1A is a schematic equivalent circuit diagram of the entire detection apparatus according to the present embodiment. FIG. 1B is an equivalent circuit diagram of one pixel of the detection device according to the present embodiment.

  The detection device in this embodiment includes a plurality of pixels 301 on an insulating substrate such as a glass substrate, and a pixel array in which the plurality of pixels 301 are arranged in a row direction and a column direction. Each pixel 301 includes a conversion element 110, a first thin film transistor 120, a second thin film transistor 130, a third thin film transistor 140, and a capacitor element 150. The conversion element 110 includes two electrodes, a first electrode electrically separated for each pixel and a second electrode connected in common. The first electrode of the conversion element 110 is connected to the gate of the first thin film transistor 120. The second electrode of the conversion element 110 is connected to the bias power source 304. Here, in this embodiment, a PIN photodiode is used as the conversion element 110 that converts radiation or light into electric charge. The bias power supply 304 uses a potential Vs for causing the photodiode to be reverse-biased to the electrode wiring. The second electrode is supplied through 260. The first thin film transistor 120 functions as an amplification transistor for amplifying and outputting the charge generated in the conversion element. The second thin film transistor 130 is for selecting a pixel, and the third thin film transistor 140 is for resetting the connection node between the gates of the conversion element 110 and the first transistor 120 to the potential Vss. The gates of the plurality of second thin film transistors 130 arranged in the row direction are commonly connected to the selection drive wiring 210, and the selection drive wiring 210 is connected to the drive circuit 302. One of the sources and drains of the plurality of second thin film transistors 130 arranged in the column direction is commonly connected to the signal wiring 220, and the signal wiring 220 is connected to the readout circuit 303. The gates of the plurality of third thin film transistors 140 arranged in the row direction are commonly connected to the reset driving wiring 230, and the reset driving wiring 230 is connected to the driving circuit 302. The driving circuit 302 supplies the conduction voltage of the second thin film transistor 130 to the selection driving wiring 210 and the conduction voltage of the third thin film transistor 140 to the reset driving wiring 230 at a desired timing, respectively. The reset operation is controlled. One of the source and the drain of the first thin film transistor 120 is supplied with the potential Vdd from the first power supply circuit 305 through the first power supply wiring 200. One of the source and the drain of the third thin film transistor 140 is supplied with the potential Vss from the second power supply circuit 306 through the second power supply wiring 240. Note that when the potential Vdd and the potential Vss are the same, each power supply and each power supply wiring may be shared. The capacitor 150 is connected to the first thin film transistor 120 in parallel with the conversion element 110, and one electrode of the capacitor 150 is connected to the first electrode of the conversion element 110. The other electrodes of the plurality of capacitor elements 150 arranged in the row direction are connected to the capacitor wiring 250, and the capacitor wiring 250 is connected to the drive circuit 302. In this embodiment, the capacitor wiring 250 and the drive circuit 302 are used as the potential supply means of the present invention. Here, the capacitive element 150 has a variable capacitance, and has a structure that can change the capacitance value of the pixel in accordance with the shooting mode. For example, when used in fluoroscopic imaging (moving imaging) mode for medical image diagnosis, the amount of radiation used for capturing one image is smaller than that in general imaging (still image capturing) mode, so the saturated charge amount of a pixel May be smaller than in the general shooting mode. Therefore, in the fluoroscopic imaging mode, the capacitance value of the pixel can be reduced to reduce the saturation charge amount and the sensitivity can be increased as compared with the general imaging mode. On the other hand, when used in the general imaging mode, since the radiation dose used for imaging one image is larger than in the fluoroscopic imaging mode, the saturation charge amount of the pixel must be larger than in the general imaging mode. Therefore, in the general imaging mode, the capacitance value of the pixel is increased as compared with the fluoroscopic imaging mode. In the present embodiment, the PIN type photodiode is used as the conversion element, but the present invention is not limited to this. Other photoelectric conversion elements such as MIS type photoelectric conversion elements may be used as long as the conversion elements convert light into electric charges. In addition, if the conversion element converts radiation into electric charges, the photoelectric conversion element described above and a scintillator that converts the radiation disposed above into visible light may be used. An element that directly converts radiation into electric charges without including a scintillator may be used. As an element that directly converts radiation into electric charge, for example, an element using selenium as a semiconductor material provided between two electrodes can be cited.

  Next, the configuration of one pixel of the detection device according to the first embodiment of the present invention will be described with reference to FIGS. 2 (a) and 2 (b). 2A is a plan view per pixel, and FIG. 2B is a cross-sectional view taken along the line A-A ′ in FIG. In FIG. 2A, only the components below the first electrode 111 of the conversion element 110, which will be described later, are shown for simplification of the drawing.

  As shown in FIG. 2A, the gate electrode of the first thin film transistor 120 is connected to the first electrode 111 of the conversion element 110 in the contact hole CH1. The other of the source and the drain of the third thin film transistor 140 is connected to the first electrode 111 of the conversion element 110 in the contact hole CH2. One electrode of the capacitive element 150 is connected to the first electrode 111 of the conversion element 110 in the contact hole CH3. Here, since the capacitor 150 has a large capacitance value, the capacitor 150 is preferably laid out so as to have as large an area as possible. The first thin film transistor 120, the second thin film transistor 130, the third thin film transistor 140, and the capacitor 150 are respectively disposed between the conversion element 110 and the insulating substrate 100. Each wiring other than the electrode wiring 260 is also disposed between the conversion element 110 and the insulating substrate 100.

  Next, as shown in FIG. 2B, the conversion element 110 includes, in order from the substrate 100 side, a first electrode 111, a first conductivity type impurity semiconductor layer 112, a semiconductor layer 113, and a second conductivity type. An impurity semiconductor layer 114 and a second electrode 115 are included. In the present embodiment, the first conductivity type impurity semiconductor layer 112 is composed of n-type amorphous silicon, and the second conductivity type impurity semiconductor layer 114 is composed of p-type amorphous silicon. A third insulating layer 103 and an interlayer insulating layer 105 are disposed between the conversion element 110 and each transistor. In addition, the second insulating layer 102, the third insulating layer 103, and the interlayer insulating layer 105 are disposed between the conversion element 110 and the capacitor 150.

  The third thin film transistor 140 includes a semiconductor layer, a first insulating layer 101, a gate 144, a second insulating layer 102, and an electrode 145 in order from the substrate 100 side. The semiconductor layer of the third thin film transistor 140 includes a semiconductor region 142, an impurity semiconductor region 141 having a higher impurity concentration than the semiconductor region 142, and an impurity semiconductor region 143 having a higher impurity concentration than the semiconductor region 142. The semiconductor region 142 is a region of the semiconductor layer where the orthogonal projection of the gate 144 is located, and the impurity semiconductor region 141 and the impurity semiconductor region 143 are regions of a semiconductor layer doped with impurities of the same conductivity type, one of which is a source The other is a region functioning as a drain. In the present embodiment, the semiconductor layer of the third thin film transistor 140 is made of a polycrystalline semiconductor material such as polycrystalline amorphous silicon. The gate 144 is electrically connected to the reset driving wiring 230. Impurity semiconductor region 141 is connected to reset wiring 240 through electrode 145, and impurity semiconductor region 143 is connected to first electrode 111 of conversion element 110 in contact hole CH2 through electrode 145. Although not shown, the first thin film transistor 120 and the second thin film transistor 130 have a layer prepared in the same formation process as the third thin film transistor 140 and have substantially the same layer configuration.

  Further, the capacitor 150 includes, in order from the substrate 100 side, a semiconductor layer that can function as one electrode, a first insulating layer 101, and a conductive layer 154 that is the other electrode. The semiconductor layer of the capacitor 150 includes an impurity semiconductor region 151, a semiconductor region 152, and an impurity semiconductor region 153. The impurity semiconductor region 151 and the impurity semiconductor region 153 are regions of a semiconductor layer doped with impurities of the same conductivity type. In the present embodiment, the impurity semiconductor region 153 is not essential. The semiconductor region 152 functions as a semiconductor portion of the present invention. In this embodiment, the semiconductor region 152 is a region of the semiconductor layer where the orthogonal projection of the conductive layer 154 is located. The impurity semiconductor region 151 is connected to the first electrode 111 of the conversion element 110 in the contact hole CH3 and functions as an ohmic contact portion of the present invention. This ohmic contact portion is for making ohmic contact between the first electrode 111 and the semiconductor region 152. The conductive layer 154 is connected to the capacitor wiring 250, the capacitor wiring 250 is connected to the driving circuit 302, and functions as a conductor portion of the present invention to which at least the first potential and the second potential are supplied from the driving circuit 302. . The conductor portion is disposed to face the semiconductor portion and the ohmic contact portion with the first insulating layer 101 interposed therebetween. For example, when the impurity doped in the impurity semiconductor region 151 is n + type, electrons are induced at the interface on the conductive layer 154 side of the semiconductor region 152 when a desired positive potential is supplied to the conductive layer 154, so-called Carrier accumulation occurs. When carriers that are charge carriers in the semiconductor are accumulated in the semiconductor region 152, the semiconductor region 152 functions as a conductor and functions as one electrode of the capacitor 150. Accordingly, the capacitance value of the capacitor 150 becomes a capacitance value that depends on the area where the semiconductor region 152 and the conductive layer 154 overlap and the dielectric constant of the first insulating layer 101. In this application, the potential applied to the conductive layer 154 so that the semiconductor layer of the capacitor 150 functions as an electrode is the first potential. On the other hand, when a ground potential or a desired negative potential is supplied to the conductive layer 154, the semiconductor region 152 is depleted. When the semiconductor region 152 is depleted, the specific resistance of the semiconductor region 152 increases, so that the semiconductor region 152 functions as an insulator and does not function as one electrode of the capacitor 150. Accordingly, the capacitance value of the capacitor 150 becomes a capacitance value resulting from capacitive coupling between the impurity semiconductor region 151 and the conductive layer 154, and the capacitance value is negligibly small compared to the capacitance value of the conversion element 110. In this application, the potential applied to the conductive layer 154 is the second potential so that the semiconductor layer of the capacitor 150 does not function as an electrode. As described above, by selectively applying the first potential and the second potential to the conductive layer 154 by the capacitor wiring 250 which is a potential supply unit and the driving circuit 302, the capacitance value of the capacitor 150 connected to the conversion element 110. Can be adjusted. That is, when the first potential is supplied to the conductive layer 154, the capacitance value of the capacitor 150 is added to the conversion element 110, and when the second potential is supplied to the conductive layer 154, The capacitance value of the capacitive element 150 is not added to the conversion element 110. For the first insulating layer 101, an insulating film having a high dielectric constant such as a TEOS (tetraethyl orthosilicate) film or a silicon oxide film is preferably used. In addition, regarding the film thickness of the first insulating layer 101, by setting the thickness to about 50 to 200 nm, the capacitor 150 having a suitable capacitance value can be obtained. In this embodiment, the semiconductor layer of the capacitor 150 is made of a polycrystalline semiconductor material such as polycrystalline amorphous silicon, and the capacitor 150 has a layer prepared in the same formation process as the third thin film transistor 140 and the like. Thus, the layer structure is substantially the same. For example, the semiconductor layer of the capacitor 150 is prepared in the same formation process as the semiconductor layer of the third thin film transistor and the conductive layer 154 is prepared in the same formation process.

  Next, another example of one pixel of the detection apparatus according to the first embodiment of the present invention will be described with reference to FIGS. 3 (a) and 3 (b). 3 (a) and 3 (b), the same numbers or symbols are assigned to those described with reference to FIGS. 2 (a) and 2 (b), and detailed description thereof is omitted.

  Other examples shown in FIGS. 3A and 3B are different from the embodiment described with reference to FIGS. 2A and 2B in the following points. In another example, the fourth thin film transistor 160 is disposed between the conversion element 110 and the capacitor 150, and the connection between the conversion element 110 and the capacitor 150 is controlled by the fourth thin film transistor 160. The fourth thin film transistor 160 includes a semiconductor layer, a first insulating layer 101, and a gate 164 in order from the substrate 100 side. The semiconductor layer of the fourth thin film transistor 160 includes a semiconductor region 162, an impurity semiconductor region 161 having a higher impurity concentration than the semiconductor region 162, and an impurity semiconductor region 163 having a higher impurity concentration than the semiconductor region 162. The semiconductor region 162 is a region of the semiconductor layer where the orthogonal projection of the gate 164 is located. The impurity semiconductor region 161 and the impurity semiconductor region 163 are regions of a semiconductor layer doped with impurities of the same conductivity type, and one of them is used as a source. The other is a region functioning as a drain. In the present embodiment, the semiconductor layer of the fourth thin film transistor 160 is made of a polycrystalline semiconductor material such as polycrystalline amorphous silicon. The gate 144 is connected to the capacitor wiring 250, and the capacitor wiring 250 is connected to the driving circuit 302, and at least the first potential and the second potential are supplied from the driving circuit 302. The impurity semiconductor region 161 is connected to the first electrode 111 of the conversion element 110 in the contact hole CH3, and the impurity semiconductor region 163 is connected to the impurity semiconductor region 151 of the capacitor 150. Note that the fourth thin film transistor 160 has a layer prepared in the same formation process as the third thin film transistor 140 and the like, and has a substantially similar layer configuration. In this example, the impurity semiconductor region 163 is shared with the impurity semiconductor region 151 of the capacitor 150.

  In the capacitor 150, the polycrystalline semiconductor semiconductor region 152 functions as an electrode when the first potential is supplied to the conductive layer 154, and the polycrystalline semiconductor semiconductor region when the second potential is supplied to the conductive layer 154. 152 does not function as an electrode. However, when the area of the capacitive element is increased in order to increase the capacitance value of the capacitive element 150, the probability that a crystal grain boundary exists in the semiconductor region 152 increases, and the probability that a potential path exists in the semiconductor region 152 increases. Get higher. Therefore, in the capacitor 150 of a pixel in which a crystal grain boundary exists, the semiconductor region 152 may function as an electrode even when the second potential is supplied to the conductive layer 154. Therefore, in this other example, the fourth thin film transistor 160 is provided between the conversion element 110 and the capacitor 150. The gate of the fourth thin film transistor 160 is connected to the capacitor wiring 250 and supplied with the first potential and the second potential. The fourth thin film transistor 160 is turned on when the first potential is supplied to the gate, and is turned off when the second potential is supplied to the gate. As a result, when the second potential is supplied to the conductive layer 154 of the capacitor 150, the electrical connection with the conversion element 110 is cut off, and it is possible to perform reliable capacitance modulation.

  In the present embodiment, the capacitor wiring 250 and the drive circuit 302 are used as the potential supply means. However, the present invention is not limited to this. Instead of the driving circuit 302, a power supply circuit capable of supplying the first potential and the second potential may be used.

  In the present embodiment, the configuration of the active pixel sensor having the first to third thin film transistors has been described. However, the present invention is not limited thereto. The present invention is also applicable to a detection device using a thin film transistor in which one of a source and a drain is connected to a conversion element and the other of the source and the drain is connected to a signal wiring.

  In the present embodiment, an upper gate type thin film transistor using a polycrystalline semiconductor is described as each thin film transistor. However, the present invention is not limited to this. An inverted staggered thin film transistor using an amorphous semiconductor such as amorphous silicon may be used. In that case, each impurity semiconductor region serving as an ohmic contact portion is preferably replaced with an impurity semiconductor layer.

(Second Embodiment)
Next, a second embodiment of the present invention will be described. In the second embodiment, a capacitive element having a larger capacitance value than that in the first embodiment is arranged, and when a second potential is applied to the capacitive element, the electrode of the capacitive element is set to a fixed potential. Connecting. Note that the same numbers and symbols are assigned to the same components as those described in the first embodiment, and detailed description thereof is omitted.

  First, a schematic equivalent circuit of the detection apparatus according to the present embodiment will be described with reference to FIGS. 4 (a) and 4 (b). FIG. 4A is a schematic equivalent circuit diagram of the detection apparatus according to the present embodiment. FIG. 4B is an equivalent circuit diagram of one pixel in the present embodiment.

  The detection device in the present embodiment further includes a fifth thin film transistor 170 in addition to the configuration of one pixel in the first embodiment. In FIGS. 4A and 4B, the capacitor 150 is described as a TFT and a capacitor connected to the TFT. One of the source and the drain of the fifth thin film transistor 170 is connected to one electrode of the capacitor 150, and the other of the source and the drain of the fifth thin film transistor 170 is a fourth power supply for supplying a fixed potential via the fixed potential wiring 270. 307. Here, examples of the fixed potential include a ground potential. The gate of the fifth thin film transistor 170 is connected to the drive circuit 302 via the switching drive wiring 280. The configuration including the fifth thin film transistor 170, the fixed potential wiring 270, and the fourth power source 307 functions as the fixed potential supply means of the present invention.

  Next, the configuration of one pixel according to the second embodiment of the present invention will be described with reference to FIGS. 5, 6A, and 6B. 5 is a plan view of one pixel, FIG. 6A is a cross-sectional view taken along the line AA ′ in FIG. 5, and FIG. 6B is a cross-sectional view taken along the line BB ′ in FIG. .

  The capacitor 150 includes, in order from the substrate 100 side, a semiconductor layer that can function as one electrode, a first insulating layer 101, a conductive layer 154 that is the other electrode, a second insulating layer 102, and an electrode layer. 155. The semiconductor layer of the capacitor 150 includes an impurity semiconductor region 151, a semiconductor region 152, and an impurity semiconductor region 153, and the impurity semiconductor region 151 is connected to the conversion element 110. The electrode layer 155 is connected to the impurity semiconductor region 153 that is opposed to the impurity semiconductor region 151 with the semiconductor region 152 interposed therebetween. This impurity semiconductor region 153 functions as another ohmic contact portion of the present invention. With this structure, when the first potential is supplied to the conductive layer 154, a capacitance is formed between the conductive layer 154 and the electrode layer 155 in addition to the capacitance of the semiconductor region 152 and the conductive layer 154. Accordingly, it is possible to form a large capacitance value as compared with the capacitive element 150 of the first embodiment.

  The fifth thin film transistor 170 includes a semiconductor layer, a first insulating layer 101, a gate 174, and a second insulating layer 102 in this order from the substrate 100 side. The semiconductor layer of the fifth thin film transistor 170 includes a semiconductor region 172, an impurity semiconductor region 171 having a higher impurity concentration than the semiconductor region 172, and an impurity semiconductor region 173 having a higher impurity concentration than the semiconductor region 172. The semiconductor region 172 is a region of the semiconductor layer where the orthogonal projection of the gate 174 is located. The impurity semiconductor region 171 and the impurity semiconductor region 173 are regions of the semiconductor layer doped with impurities of the same conductivity type, and one of them is used as a source. The other is a region functioning as a drain. The impurity semiconductor region 171 is shared with the impurity semiconductor region 153 of the capacitor 150 and is connected to the electrode layer 155 of the capacitor 150. The gate 174 is electrically connected to the switching drive wiring 280, and the impurity semiconductor region 173 is connected to the fixed potential wiring 270.

  Here, when the first potential is supplied to the conductive layer 154, the capacitance between the conductive layer 154 and the electrode layer 155 is added to the conversion element 110 in addition to the capacitance between the semiconductor region 152 and the conductive layer 154 of the capacitor 150. Connected. On the other hand, when the second potential is supplied to the conductive layer 154, the capacitor connected to the conversion element 110 is lost. In this way, the saturation dose of the pixel can be adjusted. Here, if the electrode layer 155 is floating when the second potential is supplied to the conductive layer 154, if the electrode layer 155 is capacitively coupled to the signal wiring 220, the potential of the signal wiring 220 is affected. It causes noise. In addition, if the electrode layer 155 is capacitively coupled to the first electrode 111 of the conversion element 110, it affects the potential of the first electrode 111 of the conversion element 110, thereby causing artifacts. Therefore, when the second potential is supplied to the conductive layer 154, the fifth thin film transistor 170 is turned on to fix the electrode layer 155 to a fixed potential, thereby capacitively coupling to the signal wiring 220 and the first electrode 111. Does not affect their potential. For this reason, it is possible to suppress the generation of noise and artifacts.

  Next, as another example of the second embodiment, a configuration in which a plurality of capacitive elements are provided in parallel will be described with reference to FIGS. 7A and 7B. With this configuration, the irradiation dose can be switched to three or more levels by switching the pixel capacity to three or more levels according to the imaging conditions. FIG. 7A is a plan view of one pixel, and FIG. 7B is a cross-sectional view taken along line A-A ′ in FIG. In another example of the present embodiment, an example in which two capacitive elements are connected in parallel to the conversion element 110 has been described. However, a configuration in which two or more capacitive elements are provided is also effective.

  The detection device in another example of the present embodiment further includes a second capacitor element 180 disposed between the capacitor element 150 and the fifth thin film transistor 170 in addition to the configuration of one pixel described above. The second capacitor element 180 includes, in order from the substrate 100 side, a semiconductor layer that can function as one electrode, a first insulating layer 101, a conductive layer 184 that is the other electrode, a second insulating layer 102, an electrode Layer 185. The semiconductor layer of the second capacitor element 180 includes an impurity semiconductor region 181, a semiconductor region 182, and an impurity semiconductor region 183, and the impurity semiconductor region 181 is connected in common with the impurity semiconductor region 153 of the capacitor element 150. The The electrode layer 185 is connected to the impurity semiconductor region 183 that faces the impurity semiconductor region 181 with the semiconductor region 182 interposed therebetween. With this structure, when the first potential is supplied to the conductive layer 184, a capacitor is formed between the conductive layer 184 and the electrode layer 185 in addition to the capacitors of the semiconductor region 182 and the conductive layer 184. The impurity semiconductor region 183 of the second capacitor element 180 is connected to the fifth thin film transistor 170.

  With this configuration, the capacity of the pixel can be switched in three stages. For example, when it is desired to disconnect the conversion element 110 and each capacitor, the second potential is supplied to the conductive layer 154 of the capacitor 150, the first potential is supplied to the conductive layer 184 of the second capacitor 180, The fifth thin film transistor 170 is turned on. Thereby, the capacitance of the pixel becomes a capacitance value formed by the first electrode 111 and the second electrode 115 of the conversion element 110. At this time, a fixed potential is supplied to the electrode layer 155 of the capacitor 150 and the electrode layer 185 of the second capacitor 180. When only the capacitor 150 is connected to the conversion element 110, the first potential is supplied to the conductive layer 154 of the capacitor 150, the second potential is supplied to the conductive layer 184 of the second capacitor 180, and the fifth The thin film transistor 170 is turned on. Accordingly, the capacitance of the pixel becomes a capacitance value obtained by adding the capacitance formed by the first electrode 111 and the second electrode 115 of the conversion element 110 and the capacitance formed by the capacitor 150. At this time, a fixed potential is supplied to the electrode layer 185 of the second capacitor element 180. When it is desired to connect the conversion element 110 and all the capacitor elements, the first potential is supplied to the conductive layer 154 of the capacitor element 150 and the conductive layer 184 of the second capacitor element 180, and the fifth thin film transistor 170 is turned off. To do. Accordingly, the capacitance of the pixel includes a capacitance formed by the first electrode 111 and the second electrode 115 of the conversion element 110, a capacitance formed by the capacitive element 150, a capacitance formed by the second capacitive element 180, The capacity value is obtained by adding

(Third embodiment)
Next, a third embodiment of the detection apparatus of the present invention will be described with reference to FIGS. 8 (a) and 8 (b), FIG. 9 (a) and FIG. 9 (b). Note that the same reference numerals and symbols are assigned to the same components as those described in the first or second embodiment, and detailed description thereof is omitted. In this embodiment, the electrode layer of the capacitor described in the second embodiment is configured to shield capacitive coupling between arbitrary conductors. In this embodiment, as an example, the shield of capacitive coupling between the signal wiring and each drive wiring is shown in FIGS. 8A and 8B, and the signal wiring is shown in FIGS. 9A and 9B. And the shield of capacitive coupling of the conversion element, respectively. However, the present invention is not limited thereto, and for example, a capacitive coupling shield between each drive wiring and the conversion element is also effective.

  First, a configuration for shielding the capacitive coupling between the signal wiring and each driving wiring will be described with reference to FIGS. 8A and 8B. FIG. 8A is a plan view of one pixel, and FIG. 8B is a cross-sectional view taken along the line A-A ′ in FIG.

  The electrode layer 155 of the capacitor 150 is disposed between the selection drive wiring 210 and the signal wiring 220 at the intersection of the selection drive wiring 210 and the signal wiring 220. Further, the electrode layer 155 of the capacitor 150 is disposed between the reset driving wiring 230 and the signal wiring 220 at the intersection of the reset driving wiring 230 and the signal wiring 220. According to this configuration, capacitive coupling between each drive wiring and the signal wiring 220 can be prevented while a fixed potential is supplied to the electrode layer 155. For this reason, the fluctuation of the potential of the signal wiring 220 due to the pulsed signal composed of the conduction voltage and the non-conduction voltage of each drive wiring is suppressed, and the noise caused by the fluctuation of the potential is redundant in the output signal. Can be prevented. In addition, by providing the electrode layer 155 only at the intersection, it is possible to shield the signal wiring 220 without unnecessarily increasing the capacitance. Thereby, an increase in noise due to an increase in the capacitance of the signal wiring 220 can be suppressed.

  Next, a configuration for shielding the capacitive coupling between the first electrode 111 of the conversion element 110 and the signal wiring will be described with reference to FIGS. 9A and 9B. 9A is a plan view of one pixel, and FIG. 9B is a cross-sectional view taken along the line A-A ′ in FIG. 9A.

  As shown in FIGS. 9A and 9B, the electrode layer 155 of the capacitive element 150 is disposed between the signal wiring 220 and the first electrode 111. Further, the electrode layer 155 of the capacitor 150 is disposed between the reset driving wiring 230 and the signal wiring 220 at the intersection of the reset driving wiring 230 and the signal wiring 220. According to this configuration, capacitive coupling between the signal wiring 220 and the first electrode 111 of the conversion element 110 can be prevented while a fixed potential is supplied to the electrode layer 155. Thereby, the fluctuation of the potential of the signal wiring 220 due to the fluctuation of the potential of the first electrode 111 is suppressed, and it is possible to prevent the noise caused by the fluctuation of the potential in the output signal from being redundant.

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

  The X-ray 6060 generated by the X-ray tube 6050 as a radiation source passes through the chest 6062 of the patient or subject 6061 and enters the conversion element 110 of the detection device 6040 of the present invention in which a scintillator is disposed above the photoelectric conversion element. . This incident X-ray includes information inside the body of the patient 6061. The scintillator emits light in response to the incidence of X-rays, and this is photoelectrically converted by a photoelectric conversion element to obtain electrical information. This information can be digitally converted and 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.

100 Insulating substrate 101 First insulating layer 110 Conversion element 120 First thin film transistor 130 Second thin film transistor 140 Third thin film transistor 141 Impurity semiconductor region 142 Semiconductor region 143 Impurity semiconductor region 144 Gate 145 Electrode 150 Capacitance element 151 Impurity semiconductor region 152 Semiconductor region 153 Impurity semiconductor region 154 Conductive layer

Claims (12)

A transistor disposed on a substrate;
A conversion element disposed on the transistor and connected to the transistor;
A semiconductor layer connected to the conversion element, and a conductor portion arranged to face the semiconductor layer via an insulating layer, are disposed between the substrate and the conversion element, and the semiconductor layer includes: a capacitive element having a semiconductor portion located in the region corresponding to the orthogonal projection of the conductive portion, and a ohmic contact portion for establishing an ohmic contact between the transducer and the semiconductor portion,
A first potential for accumulating carriers in the semiconductor portion to connect the capacitor element to the transistor in parallel with the conversion element and a second potential different from the first potential are selectively selected for the conductor portion . Potential supply means for supplying to
A detection device comprising:
The ohmic contact portion is located outside the region and connected to the conversion element and the semiconductor portion,
The second potential is a potential that does not cause the capacitor element to be connected in parallel to the conversion element with respect to the transistor by depleting the semiconductor portion so that the semiconductor portion does not function as an electrode of the capacitor element. A featured detection device .   The semiconductor layer of the capacitor and the semiconductor layer of the transistor are disposed on the same surface of the substrate, and the conductor portion and the gate of the transistor are disposed on the same surface of the insulating layer. The detection apparatus according to claim 1. The capacitive element further includes an electrode layer disposed to face the conductor portion via an insulating layer,
3. The detection device according to claim 1, wherein the electrode layer is connected to another ohmic contact portion arranged to face the ohmic contact portion with the semiconductor portion interposed therebetween.   The detection apparatus according to claim 3, further comprising fixed potential supply means for supplying a fixed potential to the electrode layer. A drive wiring connected to the gate of the transistor;
A signal line connected to one of a source and a drain of the transistor;
Further comprising
The detection device according to claim 4, wherein the drive wiring and the signal wiring are arranged between the substrate and the conversion element.   The detection device according to claim 5, wherein the electrode layer is disposed between the conductor portion and the conversion element.   The detection apparatus according to claim 6, wherein the electrode layer is disposed between the signal wiring and the conversion element. 7. The electrode layer according to claim 6, wherein the electrode layer is disposed between the drive wiring and the signal wiring at an intersection where the drive wiring and the signal wiring intersect with each other with an insulating layer interposed therebetween. Detection device.   The detection device according to claim 1, wherein the semiconductor portion and the semiconductor layer are polycrystalline semiconductors. A plurality of pixels including the conversion element and the capacitor;
The pixel further includes a first thin film transistor having a gate connected to the conversion element, a second thin film transistor for selecting the pixel, and a third thin film transistor for resetting the gate of the first thin film transistor. ,
The detection device according to claim 1, wherein the transistor is any one of the first thin film transistor, the second thin film transistor, and the third thin film transistor. A transistor disposed on a substrate;
A conversion element disposed on the transistor and connected to the transistor;
A semiconductor layer connected to the conversion element, and a conductor portion arranged to face the semiconductor layer with an insulating layer interposed between the substrate and the conversion element, and the semiconductor layer, a capacitive element having a semiconductor portion located in the region corresponding to the orthogonal projection of the conductive portion, and a ohmic contact portion for establishing an ohmic contact between the transducer and the semiconductor portion,
A first potential for connecting the capacitance element to the transistor in parallel with the conversion element and adding a capacitance value of the capacitance element to the conversion element, and a second potential different from the first potential are the conductive A potential supply means for selectively supplying to the body part;
A detection device comprising :
The ohmic contact portion is located outside the region and connected to the conversion element and the semiconductor portion,
2. The detection apparatus according to claim 1, wherein the second potential is a potential that prevents the capacitor from being connected in parallel to the conversion element with respect to the transistor by not functioning as an electrode of the capacitor . The detection device according to any one of claims 1 to 11,
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:

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