JP2006186031A - Photoelectric conversion device and radiation imager - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a photoelectric conversion device which is high in yield and sensitivity and can be manufactured at low cost. <P>SOLUTION: The photoelectric conversion device is provided with a photoelectric conversion substrate which includes a pixel part comprised of a capacitance element C11, a TFT (T11) as a photoelectric conversion element that is provided with a gate electrode 2, an insulating layer 3, a semiconductor layer 4 and a source-drain electrodes 6 and 7 having a switching function wherein one is connected with the capacitance element C11 and the other is connected with signal wiring, and a plurality of pixels are arranged two-dimensionally on an insulating substrate 1, a plurality of vias wirings connected with the capacitance elements C11, a plurality of driving wirings connected with the gate electrodes 2, and the signal wiring connected with either of the source-drain electrodes 6 and 7. The source-drain electrodes 6 and 7 are arranged in such a manner that they do not exist in an area wherein a gate electrode 22 is provided. The source-drain electrodes 6 and 7 are formed of ITO as an transparent electrode to take in more quantity of incident light. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a photoelectric conversion device and a radiation imaging device, and more particularly to a photoelectric conversion substrate, a photoelectric conversion device, and a radiation imaging substrate applied to a medical image diagnostic device, a nondestructive inspection device, an analysis device using radiation, and the like. And a radiation imaging apparatus. The present invention also relates to an image reading apparatus applied to a scanner or the like. In this specification, electromagnetic waves such as visible light, X-rays, α-rays, β-rays, γ-rays, and the like are also included in the radiation.

  Conventionally, as a representative radiation imaging apparatus of this type, a PIN-TFT structure constituted by a PIN (Positive-Intrinsic-Negative) type photoelectric conversion element and a switch TFT (Thin Film Transistor) as disclosed in Patent Document 1. 2. Description of the Related Art A radiation imaging apparatus is known that combines a radiation imaging substrate on which an optical sensor is disposed and a phosphor for converting radiation into visible light. Further, a radiation imaging substrate on which a MIS-TFT structure optical sensor composed of a MIS (Metal-Insulator-Semiconductor) type photoelectric conversion element and a switch TFT as in Patent Document 2 is disposed, and radiation is converted into visible light. There is also known a radiation imaging apparatus in combination with a phosphor for the purpose.

  Here, a radiation imaging apparatus using an optical sensor having a MIS-TFT structure will be described.

  FIG. 8 is an equivalent circuit diagram of a conventional radiation imaging apparatus, and FIG. 9 is a plan view of the pixel area. P11 to P33 are semiconductor conversion elements such as photoelectric conversion elements, and T11 to T33 are thin film transistors (TFTs), each of which constitutes a pixel, and a plurality of two-dimensionally arranged pixel areas (pixel portions) on an insulating substrate (not shown). 200 is formed. Here, 3 × 3 pixels are illustrated as the pixel array of the pixel area 200, but actually, for example, 2000 × 2000 pixels are arranged on a radiation imaging substrate (insulating substrate). Common bias lines Vs1 to Vs3, common gate lines Vg1 to Vg3, and common signal lines Sig1 to Sig3 are connected to each pixel in the pixel area 200.

  The radiation imaging substrate is cut at a predetermined cutting portion, and signal wirings Sig1 to Sig3 and bias wirings Vs1 to Vs3 are read out via a flexible printed wiring board such as TCP (tape carrier package) (not shown). ) 201, gate wirings Vg <b> 1 to Vg <b> 3 are connected to a gate driving device (driving circuit unit) 202, respectively.

  As shown in the figure, the photoelectric conversion elements P11 to P33 in the pixel area 200 are connected to common bias wirings Vs1 to Vs3, and a constant bias is applied from the readout device 201. On the other hand, the gate electrodes of the TFTs (T11 to T33) in the pixel area 200 are connected to the common gate wirings Vg1 to Vg3, and the gates of the TFTs (T11 to T33) are turned on and off from the gate driving device 202. OFF is controlled. Each TFT (T11 to T33) has a source or drain electrode connected to a common signal wiring Sig1 to Sig3, and each signal wiring Sig1 to Sig3 is connected to the reading device 201.

In the radiation imaging apparatus having the above-described configuration, the X-rays exposed toward the subject are attenuated and transmitted by the subject, and are converted into visible light by a phosphor layer (not shown). The visible light is converted into a photoelectric conversion element. It enters P11 to P33 and is converted into electric charge. This electric charge is transferred to the signal wirings Sig1 to Sig3 through the TFTs (T11 to T33) by the gate driving pulse applied by the gate driving device 202, and is read out to the outside by the reading device 201.
Japanese National Patent Publication No. 10-511817 JP 08-116044 A

  2. Description of the Related Art In recent years, with the development of liquid crystal panel manufacturing technology using TFTs, the screen size of a display unit has been increased along with the increase in size of the panel. This manufacturing technique is applied to a large area sensor having a semiconductor conversion element (photoelectric conversion element) and a TFT, and is used in various fields such as a radiation imaging apparatus such as an X-ray imaging apparatus.

  However, unlike a liquid crystal display, a radiation imaging apparatus (X-ray imaging apparatus) has a feature of digitally converting a minute signal and outputting an image. For this reason, for the purpose of increasing the sensitivity, after forming a TFT as in Patent Document 1, in order to obtain a sufficient aperture ratio that affects sensitivity on the TFT, a radiation imaging apparatus that forms a PIN photoelectric conversion element is used. A proposal has been made. In this case, since the TFT and the photoelectric conversion element are formed separately, the manufacturing process becomes complicated, and there are problems such as a decrease in yield and an increase in manufacturing cost.

  In addition, in the radiation imaging apparatus, for the purpose of achieving both high sensitivity and simplification of the manufacturing process, a proposal has been made to simultaneously form the MIS photoelectric conversion element and the TFT as in Patent Document 2. In this case, since the photoelectric conversion element and the photoelectric conversion layer (first semiconductor layer) of the TFT are formed at the same time, the film thickness is equivalent. Therefore, if the photoelectric conversion layer is made thick to increase the sensitivity, the ON resistance of the TFT increases and the transfer capability decreases. Therefore, when the TFT size is increased, the aperture ratio decreases. Therefore, the photoelectric conversion element and the TFT are set to a size that balances the characteristics of both, and the sensitivity characteristics and the price are balanced. However, further enhancement of sensitivity is desired.

  That is, in both Patent Documents 1 and 2, it is insufficient to say that both low cost and high functionality, particularly high sensitivity, are realized.

  In order to achieve high sensitivity, not only increasing the aperture ratio, it is important to reduce noise without degrading the transfer capability of the TFT. In particular, when the area sensor is used as an image reading device, the elements are two-dimensionally arranged, and therefore, the parasitic capacitance of the signal wiring for reading out the output of the TFT is increased and noise is increased as compared with the one-dimensionally arranged line sensor. . That is, in order to achieve high sensitivity, it is necessary to reduce noise. This is a problem not only in the radiation imaging apparatus but also in the image reading apparatus.

  The present invention has been made in consideration of such a conventional situation, and an object thereof is to provide a high-sensitivity image reading apparatus and radiation imaging apparatus that can be manufactured at a high yield and at a low cost.

  In order to achieve the above object, a photoelectric conversion device according to the present invention includes a capacitor, a gate electrode, an insulating layer, a semiconductor layer, and one connected to the capacitor and the other connected to a signal wiring on a substrate. A photoelectric conversion element having source / drain electrodes, a pixel portion in which a plurality of pixels are arranged two-dimensionally, a plurality of bias wirings connected to the plurality of capacitance elements, and a plurality of the gate electrodes, A photoelectric conversion substrate including a plurality of connected drive wirings and a signal wiring connected to one of the plurality of source / drain electrodes, wherein the source / drain electrodes are provided with the gate electrodes It is arranged so that it does not exist on the area.

  In the present invention, it is more preferable that the source / drain electrodes are arranged to have an opening region larger than the region.

  In the present invention, the capacitive element accumulates the electric charge generated in the semiconductor layer in response to the light, and the photoelectric conversion element accumulates the electric charge accumulated in the capacitive element by a driving signal from the driving wiring. You may transfer to the said signal wiring. Further, in the present invention, charge is accumulated in the capacitor element in advance, and the photoelectric conversion element discharges the charge accumulated in the capacitor element according to the light, and by a drive signal from the drive wiring, The remaining charge of the capacitive element may be transferred to the signal wiring.

  In the present invention, a drive circuit portion connected to the drive wiring and a readout circuit portion connected to the signal wiring may be further included. The bias wiring may be connected to a bias power source provided in the drive circuit unit. The bias wiring may be connected to a bias power source provided in the readout circuit unit. The source / drain electrodes may be constituted by transparent electrodes. It may further include an insulating layer disposed on a region where the pixel portion exists and a protective layer disposed on the insulating layer, and the surface of the protective layer may be formed in a planar shape.

  A radiation imaging apparatus according to the present invention includes any one of the photoelectric conversion apparatuses according to any one of the above and a wavelength converter that converts incident radiation into light that can be detected by a photoelectric conversion element of the photoelectric conversion apparatus. Features.

  According to the present invention, a capacitive element and a photoelectric conversion element having a switching function (a gate electrode, an insulating layer, a semiconductor layer, one of which is connected to the capacitive element and the other is connected to a signal wiring) are provided. In addition, since the source electrode or drain electrode of the photoelectric conversion element is configured not to overlap with the gate electrode, the manufacturing process is simplified, it can be manufactured at a high yield and at a low cost, and low noise can be achieved without reducing the transfer capability. A possible image reading apparatus and radiation imaging apparatus can be provided.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  In the radiation imaging apparatus using the photoelectric conversion device of the present embodiment, a plurality of capacitive elements and a TFT (thin film transistor) as a photoelectric conversion element having a plurality of switching functions connected to the capacitive element are provided on an insulating substrate. A radiation imaging substrate comprising a bias wiring for applying a bias to the capacitive element, a gate wiring for supplying a drive signal to the switch element, and a signal wiring for reading the TFT output, and wavelength conversion of radiation. In this configuration, a signal corresponding to the amount of radiation incident on the TFT is output, and the source electrode or drain electrode of the TFT and the gate electrode do not overlap. In the present embodiment, the source or drain electrode of the TFT is formed of a transparent electrode.

  Embodiments of a radiation imaging apparatus using the photoelectric conversion apparatus of the present invention will be described with reference to the drawings.

  FIG. 1 is an equivalent circuit diagram of the radiation imaging apparatus of the present embodiment, FIG. 2 is a plan view thereof, and FIG. 3 is a cross-sectional view of one pixel along the line AA ′ in FIG.

  The radiation imaging apparatus according to the present embodiment includes a capacitive imaging element, a radiation imaging substrate as a photoelectric conversion apparatus configured by a TFT (thin film transistor) functioning as a switch and a photoelectric conversion element, and a radiation imaging device for converting radiation into visible light. A phosphor as a wavelength converter is combined.

  As shown in FIG. 1, the radiation imaging substrate includes a capacitive element and a TFT that functions as a switch and a photoelectric conversion element. C11 to C33 are capacitive elements, and T11 to T33 are TFTs serving as switches and photoelectric conversion elements. Each of them constitutes a pixel, and a plurality of two-dimensionally arranged pixels are formed on an insulating substrate to form a pixel area (pixel portion) 100. ing. Here, 3 × 3 pixels are shown as the pixel arrangement of the pixel area 100, but actually, for example, 2000 × 2000 pixels are arranged on an insulating substrate. To each pixel in the pixel area 100, common signal wirings Sig1 to Sig3, bias wirings Vs1 to Vs3, and gate wirings Vg1 to Vg3 are connected, respectively.

  The insulating substrate on which the pixel area 100 is formed is cut at a predetermined cutting portion, and the signal wirings Sig1 to Sig3 and the bias wirings Vs1 to Vs3 are passed through a printed wiring board such as TCP (tape carrier package) not shown. Are connected to a reading device (reading circuit portion) 101, and gate wirings Vg1 to Vg3 are connected to a gate driving device (driving circuit portion) 102, respectively. The bias wirings Vs1 to Vs3 are connected to a bias power source (not shown) provided in the reading device 101.

  As shown in the figure, each of the capacitive elements C11 to C33 in the pixel area 100 has one electrode connected to a common bias wiring Vs1 to Vs3, and a constant bias is applied from a bias power source (not shown) of the reading device 101. Is done. On the other hand, the gate electrodes of the TFTs (T11 to T33) in the pixel area 100 are connected to the common gate wirings Vg1 to Vg3, and the gates of the TFTs (T11 to T33) are turned on and off from the gate driving device 102. Be controlled. Further, one of the source or drain electrodes of the TFTs (T11 to T33) is connected to the other electrode of each of the capacitive elements C11 to C33, and the other is connected to the common signal wirings Sig1 to Sig3. The signal wirings Sig1 to Sig3 are connected to the reading device 101.

  As shown in the plan view of FIG. 2, each of the TFTs (T11 to T33) includes a plurality of source electrodes or drain electrodes in a region between the capacitive elements C11 to C33 and the signal wirings Sig1 to Sig3. The signal wirings Sig1 to Sig3 are formed at predetermined intervals extending in a direction orthogonal to the direction of the signal wirings Sig1 to Sig3. In this way, the TFT size is increased.

  As shown in FIG. 3, the layer configuration of the radiation imaging apparatus includes a TFT (T11) and a capacitive element C11 on an insulating substrate 1. In the example of FIG. 3, one pixel along the line A-A ′ in the plan view of FIG. 2 is illustrated, but the layer configuration of other pixels is the same.

  The TFT (T11) includes a first electrode layer 2 that forms a gate electrode, a first insulating layer 3 that forms a gate insulating layer, and a first semiconductor that forms a photoelectric conversion layer such as amorphous silicon (a-Si). A layer 4, for example, an ohmic contact layer 5 made of an n-type semiconductor layer, and second electrode layers 6 and 7 for forming source / drain electrodes are provided.

  The source / drain electrodes (second electrode layers 6 and 7) and the gate electrode (first electrode layer 2) are arranged so as not to overlap each other. In other words, it is more desirable that the source / drain electrodes (second electrode layers 6 and 7) do not exist on the region where the gate electrode (first electrode layer 2) is disposed. 1 has an opening area larger than the area where the electrode layer 2) is disposed. By doing so, the parasitic capacitance of the signal wiring generated when the source / drain electrodes overlap with the gate electrode can be reduced, and low noise can be achieved. Further, since the parasitic capacitance is further reduced by increasing the distance between the source / drain electrodes and the gate electrode, the opening region is more preferably larger than the region where the gate electrode is disposed. Further, it is more desirable that the opening region is larger than the region where the gate electrode is provided in order to prevent alignment misalignment when the source / drain electrode is formed and the source / drain electrode and the gate electrode overlap. .

  The source / drain electrodes (second electrode layers 6 and 7) are made of ITO (Indium Tin Oxide), which is a transparent electrode, in order to obtain a larger amount of incident light with respect to the photoelectric conversion layer (first semiconductor layer 4). It is configured.

  The capacitive element C11 includes a first electrode layer 8 that forms a G electrode, a first insulating layer 9 that forms an insulating layer, and a third electrode layer 10 that forms a D electrode. The electrode layer 8) is connected to one of the source / drain electrodes (second electrode layers 6 and 7) of the TFT (T11).

  The gate wiring Vg1 is formed of the first electrode layer, and is connected to the gate electrode (first electrode layer 2) of the TFT (T11). The signal wiring Sig1 is formed of a third electrode layer, and is connected to the other of the source / drain electrodes (second electrode layers 6 and 7) of the TFT (T11). The bias wiring Vs1 is formed of a third electrode layer, and is connected to the D electrode (third electrode layer 10) of the capacitor C11.

  On these layers, a second insulating layer 11 made of SiNx or the like and an organic protective layer 12 made of polyimide or the like are formed. In addition to protecting the lower layer, the organic protective layer 12 changes the surface shape on which the phosphor layer 14 is formed from a complicated uneven shape along the arrangement shape of the source / drain electrodes of the TFT (T11) to a flat (planar) shape. Also play a role such as.

Furthermore, a phosphor layer 14 is disposed on the upper layer via an adhesive layer 13. For example, when the first semiconductor layer 4 is amorphous silicon (a-Si), the phosphor layer 14 is an alkali having a columnar crystal structure such as CsI having an emission wavelength substantially close to the photosensitive wavelength of a-Si. Halide-based materials are desirable. Further, it may be formed by direct vapor deposition without providing the adhesive layer 13. Further, the phosphor layer 14 may be made of a phosphor material having a particulate crystal structure such as gadolinium oxysulfide (Gd ₂ O ₂ S ₃ ) in addition to CsI.

  Next, the operation of this embodiment will be described.

  First, X-rays exposed toward the subject are attenuated and transmitted by the subject, and are converted into visible light by the phosphor layer 14 shown in FIG. 3, and the visible light is used as a switch and a photoelectric conversion element. It enters the functioning TFT (T11 to T33) and is converted into electric charge. This electric charge is accumulated in the capacitive elements C11 to C33, transferred to the signal wirings Sig1 to Sig3 via the TFTs (T11 to T33) by the gate driving pulse applied by the gate driving device 102, and read out to the outside by the reading device 101. It is. Thereafter, the capacitive elements C11 to C33 are reset by the common bias wirings Vs1 to Vs3 or via the TFTs (T11 to T33).

  Therefore, according to the radiation imaging apparatus of the present embodiment, comparing the mutual layer configuration of the capacitive element and the TFT, there is no layer formed only for the capacitive element formation, so that the manufacturing process can be simplified. It becomes possible. In the present embodiment, the transparent electrode (second electrode layers 6 and 7) and the ohmic contact layer 5 are removed on the capacitive element C11 side, but the present invention is not necessarily limited thereto. The transparent electrode and the ohmic contact layer on the capacitor element side are not necessarily removed.

  In addition, according to the radiation imaging apparatus of the present embodiment, since the TFT has a function of a photoelectric conversion element in addition to the switch function, increasing the TFT size can increase the sensitivity and improve the transfer capability. It is possible to have an effect. Furthermore, since transparent electrodes are used as the source / drain electrodes of the TFT, the light receiving area is further increased, and further sensitivity enhancement is possible.

  Furthermore, according to the radiation imaging apparatus of this embodiment, since the TFT source / drain electrode and the gate electrode are arranged so as not to overlap, the parasitic capacitance of the signal wiring can be reduced, and low noise can be achieved. is there.

  Next, a second embodiment of the image reading apparatus using the photoelectric conversion device of the present invention will be described with reference to the drawings.

  In the image reading apparatus of this embodiment, a plurality of capacitor elements and TFTs as photoelectric conversion elements having a plurality of switch functions connected to the capacitor elements are arranged in a matrix on an insulating substrate. A photoelectric conversion substrate having a bias wiring for applying a bias to the gate, a gate wiring for supplying a drive signal to the switch element, and a signal wiring for reading the output of the TFT is output, and a signal corresponding to the amount of light incident on the TFT is output. The structure is such that the source electrode or drain electrode of the TFT does not overlap with the gate electrode. In this configuration, the source or drain electrode of the TFT is formed of a transparent electrode.

  4 is an equivalent circuit diagram of the image reading apparatus of the present embodiment, FIG. 5 is a plan view, and FIG. 6 is a cross-sectional view of one pixel along the line BB ′ in FIG.

  The image reading apparatus of the present embodiment is a photoelectric conversion substrate as a photoelectric conversion apparatus including a capacitive element, a TFT (thin film transistor) that functions as a switch and a photoelectric conversion element, and a light irradiation apparatus that irradiates light on a subject. This is an image reading apparatus combined with a certain backlight.

  As shown in FIG. 4, the photoelectric conversion substrate includes a capacitive element and a TFT that functions as a switch and a photoelectric conversion element. C11 to C33 are capacitive elements, and T11 to T33 are TFTs serving as switches and photoelectric conversion elements. Each of them constitutes a pixel, and a plurality of two-dimensionally arranged pixels are formed on an insulating substrate to form a pixel area (pixel portion) 100. ing. Here, 3 × 3 pixels are shown as the pixel arrangement of the pixel area 100, but actually, for example, 2000 × 1000 pixels are arranged on the insulating substrate.

  The insulating substrate (photoelectric conversion substrate) is cut at a predetermined cutting portion, and the signal wirings Sig1 to Sig3 are connected to the reading device 101 via the printed wiring board such as TCP (tape carrier package), the bias wirings Vs1 to Vs3 and the gate. The wirings Vg1 to Vg3 are connected to the gate driving device 102, respectively. The bias lines Vs1 to Vs3 are connected to a bias power source (not shown) provided in the gate driving device 102.

  As shown in the figure, the capacitive elements C11 to C33 are connected to common bias lines Vs1 to Vs3, and a constant bias is applied from the gate driving device 102. The gate electrodes of the TFTs (T11 to T33) are connected to the common gate wirings Vg1 to Vg3, and the gate driving device 102 controls the ON and OFF of the gates of the TFTs (T11 to T33). The source or drain electrode of each TFT (T11 to T33) is connected to common signal wirings Sig1 to Sig3, and each signal wiring Sig1 to Sig3 is connected to the reading device 101.

  As shown in the plan view of FIG. 5, each of the TFTs (T11 to T33) includes a plurality of source electrodes or drain electrodes in a region between the capacitive elements C11 to C33 and the signal wirings Sig1 to Sig3. The signal wirings Sig1 to Sig3 are formed at predetermined intervals extending in a direction orthogonal to the direction of the signal wirings Sig1 to Sig3. In this way, the TFT size is increased.

  As shown in FIG. 3, the layer configuration of the image reading apparatus includes a TFT (T11) and a capacitor C11 on an insulating substrate 21.

  The TFT (T11) includes a first electrode layer 22 that forms a gate electrode, a first insulating layer 23 that forms a gate insulating layer, a first semiconductor layer 24 that forms a photoelectric conversion layer, an n-type semiconductor layer, and the like. An ohmic contact layer 25 and second electrode layers 26 and 27 for forming source / drain electrodes are provided.

  The source / drain electrodes (second electrode layers 26 and 27) and the gate electrode (first electrode layer 22) are arranged so as not to overlap each other. That is, it is more desirable that the source / drain electrodes (second electrode layers 26 and 27) do not exist on the region where the gate electrode (first electrode layer 22) is disposed. The electrode layer 2) is disposed with an opening region larger than the region where the electrode layer 2) is disposed. By doing so, the parasitic capacitance of the signal wiring generated when the source / drain electrodes overlap with the gate electrode can be reduced, and low noise can be achieved. Further, since the parasitic capacitance is further reduced by increasing the distance between the source / drain electrodes and the gate electrode, the opening region is more preferably larger than the region where the gate electrode is disposed. Further, it is more desirable that the opening region is larger than the region where the gate electrode is provided in order to prevent alignment misalignment when the source / drain electrode is formed and the source / drain electrode and the gate electrode overlap. .

  The capacitive element C11 includes a first electrode layer 28 that forms a G electrode, a first insulating layer 29 that forms an insulating layer, and a second electrode layer 30 that forms a D electrode. The D electrode (second electrode layer 30) of the capacitive element C11 and the source / drain electrodes (second electrode layers 26, 27) of the TFT (T11) are formed of the same second electrode layer, and D The electrode (second electrode layer 30) and the source or drain electrode (second electrode layers 26, 27) are connected.

  The gate wiring Vg1 is formed from the first electrode layer, and is connected to the gate electrode (first electrode layer 22) of the TFT (T11). The signal wiring Sig1 is formed from the second electrode layer and is connected to the source / drain electrodes (second electrode layers 26 and 27). The bias wiring Vs1 is formed of the first electrode layer, and is connected to the G electrode (first electrode layer 28) of the capacitor C11.

  On these layers, a second insulating layer 31 made of SiNx or the like and an organic protective layer 32 made of polyimide or the like are formed.

  A light shielding layer 41 is formed below the TFT (T11) with the insulating substrate 21 interposed therebetween. This is intended to prevent generation of a bright current of the TFT (T11) due to light other than the reflected light of the subject (original) OB irradiated from the backlight 51.

  Next, the operation of the image reading apparatus will be described.

  First, using the bias wirings Vs1 to Vs3 and the TFTs (T11 to T33), the capacitors C11 to C33 are charged with a constant charge. At this time, the TFTs (T11 to T33) are turned on. Thereafter, light is emitted from the backlight 51 with the TFTs (T11 to T33) turned off. This light is transmitted between the elements of the photoelectric conversion substrate and reflected according to the image information of the subject (original) OB. The reflected light enters the TFTs (T11 to T33) functioning as switches and photoelectric conversion elements, and a current (bright current) flows between the sources and drains of the TFTs (T11 to T33) to charge the capacitive elements C11 to C33. The charge is discharged. Subsequently, the backlight 51 is turned off, and the TFTs (T11 to T33) are sequentially turned on by the gate driving device 102 and the reading device 101. As a result, charges remaining in the capacitive elements C11 to C33 are transferred to the signal wirings Sig1 to Sig3 and read out to the outside.

  Therefore, according to the photoelectric conversion device of this embodiment and the image reading device using the photoelectric conversion device, when the layer configuration (FIG. 6) of the capacitance element and the TFT is compared as in the first embodiment, the capacitance element is formed. Since only one layer is not formed, the manufacturing process can be simplified. Note that the ohmic contact layer on the capacitor element side may not be removed.

  Further, according to the photoelectric conversion device of this embodiment and the image reading apparatus using the same, since the TFT also has a function of a photoelectric conversion element as in the first embodiment, it is possible to increase the sensitivity by increasing the TFT size. It is possible to have two effects, that is, the improvement of transmission performance and transfer capability.

Further, according to the photoelectric conversion device of the present embodiment and the image reading device using the photoelectric conversion device, the source / drain electrodes and the gate electrodes of the TFTs are arranged so as not to overlap as in the first embodiment. The parasitic capacitance of the signal wiring can be reduced, and noise reduction can be achieved.
[Application Example 1]
FIG. 7 shows an application example of the radiation imaging apparatus using the photoelectric conversion apparatus according to the present invention to an X-ray diagnostic system.

  X-rays 6060 generated by the X-ray tube 6050 pass through the chest 6062 of the patient or subject 6061 and enter a radiation imaging apparatus 6040 having a scintillator (phosphor) mounted thereon. 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 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.

  As described above, the present invention relates to a photoelectric conversion substrate and a photoelectric conversion device, a radiation imaging substrate, and a radiation imaging device that are applied to a medical diagnostic imaging device, a nondestructive inspection device, an analysis device using radiation, and the like. It can also be applied to applications such as image reading devices applied to scanners and the like.

It is the equivalent circuit schematic of the radiation imaging device by Example 1 using the photoelectric conversion apparatus of this invention. It is a top view of the radiation imaging device shown in FIG. FIG. 3 is a cross-sectional view of one pixel along the line A-A ′ in FIG. 2. It is an equivalent circuit diagram of an image reading device according to an application example of the present invention. It is a top view of the image reading apparatus using the photoelectric conversion apparatus of this invention shown in FIG. FIG. 6 is a cross-sectional view of one pixel taken along line B-B ′ in FIG. 5. It is the schematic explaining the application example to the X-ray diagnostic system of the radiation imaging device using the photoelectric conversion apparatus of this invention. It is the equivalent circuit schematic of the radiation imaging device of a prior art example. It is a top view of the radiation imaging device shown in FIG.

Explanation of symbols

100 pixel area (pixel part)
101 Reading device (reading circuit unit)
102 Gate drive device (drive circuit section)
P11 to P33 Photoelectric conversion element (semiconductor conversion element)
C11 to C33 Capacitance elements T11 to T33 Thin film transistors (TFTs)
Vg1 to 3 Common gate wiring Sig1 to 3 Common signal wiring Vs1 to 3 Common bias wiring

Claims (10)

A pixel comprising a capacitor and a photoelectric conversion element having a gate electrode, an insulating layer, a semiconductor layer, and a source / drain electrode, one of which is connected to the capacitor and the other is connected to a signal wiring, over a substrate. A plurality of two-dimensionally arranged pixel portions, a plurality of bias wirings connected to the plurality of capacitive elements, a plurality of driving wirings connected to the plurality of gate electrodes, and a plurality of the source / drain electrodes The signal wiring connected to one of the, and a photoelectric conversion substrate,
The photoelectric conversion device according to claim 1, wherein the source / drain electrodes are arranged so as not to exist on a region where the gate electrode is provided.   The photoelectric conversion device according to claim 1, wherein the source / drain electrodes are arranged to have an opening region larger than the region. The capacitive element accumulates the charge generated in the semiconductor layer in response to the light,
The photoelectric conversion device according to claim 1, wherein the photoelectric conversion element transfers the electric charge accumulated in the capacitor element to the signal wiring in accordance with a driving signal from the driving wiring. In the capacitor element, charges are accumulated in advance,
The photoelectric conversion element discharges the electric charge accumulated in the capacitive element according to the light, and transfers the remaining electric charge of the capacitive element to the signal wiring in accordance with a driving signal from the driving wiring. The photoelectric conversion device according to claim 1 or 2. A drive circuit unit connected to the drive wiring;
5. The photoelectric conversion device according to claim 1, further comprising a readout circuit portion connected to the signal wiring.   The photoelectric conversion apparatus according to claim 5, wherein the bias wiring is connected to a bias power source provided in the drive circuit unit.   The photoelectric conversion device according to claim 5, wherein the bias wiring is connected to a bias power source provided in the readout circuit unit.   The photoelectric conversion device according to claim 1, wherein the source / drain electrodes are configured by transparent electrodes. An insulating layer disposed on a region where the pixel portion exists;
A protective layer disposed on the insulating layer;
The photoelectric conversion device according to claim 1, wherein a surface of the protective layer is formed in a planar shape. The photoelectric conversion device according to any one of claims 1 to 9,
A radiation imaging apparatus comprising: a wavelength converter that converts incident radiation into light that can be sensed by a photoelectric conversion element of the photoelectric conversion apparatus.