Radiation imaging device

Abstract

To improve the reliability of pixel repair and / or the aperture ratio.SOLUTION: A radiation imaging device includes a plurality of pixels, each including a photoelectric conversion element and a switching element, a bias wiring that supplies a bias voltage to the photoelectric conversion elements of the plurality of pixels, and a first removal portion in which at least a portion of the connection between the photoelectric conversion elements of some of the pixels and the bias wiring is removed to provide insulation between the photoelectric conversion elements of some of the pixels among the plurality of pixels and the bias wiring, and the photoelectric conversion elements of the other pixels among the plurality of pixels are electrically connected to the bias wiring.SELECTED DRAWING: Figure 8

Description

[Technical field]

[0001] The present disclosure relates to a radiation imaging apparatus. [Background technology]

[0002] Radiation imaging devices that combine a sensor substrate in which switching elements such as thin film transistors and photoelectric conversion elements made of amorphous silicon or the like are arranged in a two-dimensional matrix on an insulating substrate with a scintillator that converts radiation into visible light are widely used. In the manufacturing process of radiation imaging devices, there is a certain probability that pixel defects such as wiring shorts and breaks caused by particles or process defects will occur. Therefore, in addition to process management and process development to reduce the occurrence of defects, pixel repair technology is used to repair specific parts of defective pixels and suppress abnormal outputs from the defective pixels and surrounding normal pixels.

[0003] For example, Patent Document 1 discloses a repair method for removing the connection between the signal wiring and the TFT, and the connection between the pixel electrode and the TFT. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2004-179645 A Summary of the Invention [Problem to be solved by the invention]

[0005] Patent Document 1 has the following problems (1) and (2).

[0006] (1) Reliability of repair A pixel becomes defective when any of a number of leak paths occurs. However, in Patent Document 1, pixel repair is not possible for all leak paths, but rather for some leak paths.

[0007] (2)Aperture ratio In the pixel repair method of Patent Document 1, in order to secure an area for pixel repair, the area of ​​the photoelectric conversion element is reduced, resulting in a decrease in the aperture ratio.

[0008] An object of the present disclosure is to make it possible to improve the reliability of pixel repair and / or the aperture ratio. [Means for solving the problem]

[0009] The radiation imaging device has a plurality of pixels, each including a photoelectric conversion element and a switching element, a bias wiring that supplies a bias voltage to the photoelectric conversion elements of the plurality of pixels, and a first removal portion in which at least a portion of the connection between the photoelectric conversion elements of some of the plurality of pixels and the bias wiring is removed to insulate the photoelectric conversion elements of some of the pixels among the plurality of pixels from the bias wiring, and the photoelectric conversion elements of the other pixels among the plurality of pixels are electrically connected to the bias wiring. Effect of the Invention

[0010] According to the present disclosure, it is possible to improve the reliability of pixel repair and / or the aperture ratio. [Brief description of the drawings]

[0011] [Figure 1] FIG. 2 is an equivalent circuit diagram showing a leakage path that may occur within a pixel. [Diagram 2] FIG. 13 is an equivalent circuit diagram showing pixel repair. [Diagram 3] FIG. 13 is a plan view showing pixel repair. [Figure 4] FIG. 1 is a diagram illustrating an example of the configuration of a radiation imaging apparatus. [Diagram 5] FIG. 2 is a configuration diagram of a sensor substrate. [Figure 6] 2A to 2C are a plan view, an enlarged plan view, and a cross-sectional view of a pixel. [Figure 7] 3A and 3B are a plan view and a cross-sectional view of a pixel. [Figure 8] 3A and 3B are a plan view and a cross-sectional view of a pixel. [Figure 9] FIG. [Figure 10] FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] First, problems (1) and (2) to be solved by this embodiment will be described.

[0013] (1) Reliability of repair 1 is an equivalent circuit diagram of a pixel. A pixel has at least a thin film transistor (TFT) 210 and a photoelectric conversion element 230. Within a pixel, there are portions having four different potentials: a signal line potential Vsig, a gate line potential Vg, a bias line potential Vs, and a lower electrode potential Vx. There are six possible leak paths between two of these points, indicated by dotted lines a to f, and a pixel repair method is required that can reliably repair a pixel when any of these leak paths occurs.

[0014] Fig. 2 is a diagram showing a method for repairing the pixel in Fig. 1. The parts marked with x are the repair locations. The dashed lines a, b, d to f are leak paths that can be repaired using this repair method, and the solid line c is a leak path that cannot be repaired using this repair method. If the leak path of the solid line c exists, there is a problem that pixel repair cannot be performed.

[0015] (2)Aperture ratio In pixel repair using a laser, if there are multiple metal films in the area irradiated by the laser, those metals may short out when melted or evaporated under certain conditions, so it is preferable to perform repairs in areas where two or more layers do not overlap.

[0016] Fig. 3 is a plan view of a pixel repaired by the pixel repair method of Fig. 2. In addition to a TFT 210 and a photoelectric conversion element 230, the pixel has a signal line 110, a drive line 120, and a bias line 140. The signal line 110 has a signal line potential Vsig. The drive line 120 has a gate line potential Vg. The bias line 140 has a bias line potential Vs.

[0017] Since the photoelectric conversion element 230 is not provided in the cutouts 113 and 114 where the TFT 210 is repaired and in the region of the TFT 210, the area of ​​the photoelectric conversion element 230 is reduced, resulting in a problem of a reduced aperture ratio.

[0018] The present embodiment aims to solve these problems (1) and (2). Hereinafter, the present embodiment will be described in detail with reference to the drawings.

[0019] [Before pixel repair] 4 is a diagram showing an example of the configuration of the radiation imaging device 1 according to this embodiment. The radiation imaging device 1 includes a sensor substrate 60, a readout circuit 10, a drive circuit 20, a power supply unit 30, a control and calculation unit 40, and a memory 50.

[0020] The power supply unit 30 supplies a power supply voltage to the readout circuit 10 and the drive circuit 20. The sensor substrate 60 is driven by the drive circuit 20. The sensor substrate 60 converts incident X-rays into charge signals to generate a radiographic image. The readout circuit 10 reads out the charge signals converted by the sensor substrate 60.

[0021] The control and calculation unit 40 performs processing such as correction on the charge signal read out by the readout circuit 10, and temporarily stores the signal in the memory 50. A scintillator (not shown) that converts X-rays into light such as visible light is provided opposite the sensor substrate 60. A photoelectric conversion element 230 (FIG. 5(b)) in the sensor substrate 60 converts the light converted by the scintillator into a charge signal.

[0022] 5(a) is an equivalent circuit diagram showing an example of the configuration of the sensor substrate 60 in Fig. 4, and is a diagram showing the relationship between the sensor substrate 60, the readout circuit 10, and the drive circuit 20. The sensor substrate 60 is fabricated on an insulating substrate such as a glass substrate by using a manufacturing process similar to that for liquid crystal.

[0023] 5(b) are arranged in a matrix on the sensor substrate 60. Each of the pixels 160 has a photoelectric conversion element 230 that converts light into an electric charge, and a TFT 210 that is a switching element for outputting an electric signal based on the converted electric charge. The TFT 210 is an example of a switching element.

[0024] The signal wiring 110 is commonly connected to the TFTs 210 of a plurality of pixels 160 in the column direction via connection parts 111, and is arranged in a plurality of lines in the row direction. The other end of the signal wiring 110 is connected to a readout circuit 10 for reading out electrical signals from the pixels 160 on a row-by-row basis.

[0025] The drive wiring 120 is a gate wiring, commonly connected to the gates of the TFTs 210 of a plurality of pixels 160 in the row direction via connection parts 121, and arranged in a plurality of lines in the column direction. The other end of the drive wiring 120 is connected to a drive circuit 20. When the TFTs 210 are controlled to be in an on state by the drive circuit 20, electrical signals of the photoelectric conversion elements 230 of the pixels 160 are output to the signal wiring 110 on a row-by-row basis.

[0026] The drive wiring 120 drives the TFT 210. Electric signals converted by the photoelectric conversion elements 230 of the plurality of pixels 160 are output to the signal wiring 110 via the TFTs 210 of the plurality of pixels 160.

[0027] The bias wiring 140 is commonly connected to the photoelectric conversion elements 230 of the multiple pixels 160 via a connection portion 141. The other end of the bias wiring 140 is connected to the power supply unit 30 via a bias routing wiring 150, and a bias voltage is supplied to the photoelectric conversion elements 230 to make them capable of photoelectric conversion. The bias wiring 140 supplies the bias voltage to the photoelectric conversion elements 230 of the multiple pixels 160 via the power supply unit 30.

[0028] The TFT 210 and the photoelectric conversion element 230 of each pixel 160 are connected to each other via a connection portion 131 .

[0029] Fig. 6(a) is a plan view showing an example of the layout of the pixel 160 in Fig. 5(b). Fig. 6(b) is an enlarged plan view of the periphery of the TFT 210 in Fig. 6(a). Fig. 6(c) is a cross-sectional view taken along line A-A' of the pixel 160 in Fig. 6(a).

[0030] The TFT 210 has at least an overlapping portion between any two of the gate electrode 211, the semiconductor layer 213, the source electrode 214, and the drain electrode 215. Moreover, the photoelectric conversion element 230 is not provided on the upper portion of the TFT 210 or around the periphery thereof.

[0031] The connection portion 111 connects the TFT 210 and the signal wiring 110. The connection portion 121 connects the TFT 210 and the drive wiring 120. The connection portion 131 connects the TFT 210 and the photoelectric conversion element 230. The connection portion 141 connects the photoelectric conversion element 230 and the bias wiring 140.

[0032] 6(b), the length of the connection portion 111 is the distance between the TFT 210 and the signal wiring 110. The length of the connection portion 121 is the distance between the TFT 210 and the drive wiring 120. The length of the connection portion 131 is the distance between the TFT 210 and the photoelectric conversion element 230. Of the lengths of the connection portions 111, 121, and 131, the length of the connection portion 111 is the longest. The length of the connection portion 111 is longer than the length of the connection portion 121 and the length of the connection portion 131.

[0033] Here, from the viewpoint of improving the aperture ratio, it is desirable that the lengths of the connection parts 121 and 131 are as short as possible. In Fig. 3, the cut-out part 114 is provided, so the length of the connection part 131 is long, the area of ​​the photoelectric conversion element 230 is small, and the aperture ratio is low. In contrast, in this embodiment, as shown in Fig. 6(b), the cut-out part 114 in Fig. 3 is not provided, so the length of the connection part 131 can be made shorter than the connection part 111, the area of ​​the photoelectric conversion element 230 is increased, and the aperture ratio is increased.

[0034] The connection portion 141 is a portion that electrically connects the bias wiring 140 to the upper electrode 231 of the photoelectric conversion element 230, and passes through the inside of a contact hole provided in the interlayer insulating film 250. At least a part of the connection portion 141 is provided inside a contact hole provided in the interlayer insulating film 250 between the bias wiring 140 and the photoelectric conversion element 230.

[0035] 6(c), the pixels 160 and the elements are formed on a sensor substrate 60. For example, a glass substrate or a plastic substrate may be used as the sensor substrate 60. In addition, a TFT 210 is formed on the sensor substrate 60. In this embodiment, an inverted staggered TFT is used as the TFT 210, but for example, a top-gate TFT may also be used.

[0036] The TFT 210 includes a gate electrode 211 formed of the same metal layer as the driving wiring 120, an insulating film 212, a semiconductor layer 213, a source electrode 214 formed of the same wiring as the signal wiring 110, and a drain electrode 215. Note that, although 214 is the source electrode and 215 is the drain electrode here, 214 may be the drain electrode and 215 may be the source electrode.

[0037] The insulating film 212 can function as a gate insulating film in the TFT 210. A photoelectric conversion element 230 is disposed on the TFT 210 with a protective film 220 interposed therebetween.

[0038] The photoelectric conversion element 230 has a structure in which a first impurity semiconductor layer 232, an intrinsic semiconductor layer 233, and a second impurity semiconductor layer 234 are stacked in this order between a lower electrode 235 and an upper electrode 231. The impurity semiconductor layer 232, the intrinsic semiconductor layer 233, and the impurity semiconductor layer 234 constitute a PIN photodiode, which performs photoelectric conversion. In this embodiment, a PIN photodiode is used for the photoelectric conversion element 230, but for example, an MIS type element may also be used.

[0039] Moreover, the bias wiring 140 is disposed on the photoelectric conversion element 230 via a protective film 240 and an interlayer insulating film 250. Here, the bias wiring 140 may be a metal layer or a transparent conductive film such as ITO. The pixel 160 thus formed is covered with a protective film 260.

[0040] Fig. 7(a) is a plan view showing an example layout of a pixel 160 having a different shape of the connection portion 141 from that shown in Fig. 6(a). Fig. 7(b) is a cross-sectional view taken along line A-A' in Fig. 7(a). The shape of the connection portion 141 is not limited to this. The connection portion 141 between the bias wiring 140 and the photoelectric conversion element 230 only needs to be provided at a position that overlaps with the photoelectric conversion element 230 in orthogonal projection.

[0041] [After repair] Next, a method of pixel repair for the pixel 160 will be described. Fig. 8(a) is a plan view of a repaired pixel obtained by performing pixel repair on the pixel 160 of Fig. 6(a). Fig. 8(b) is a cross-sectional view taken along line A-A' in Fig. 8(a). Fig. 9 is a plan view showing an example layout of a plurality of pixels 160.

[0042] In pixel repair, the areas to be cut are cut portion 112 including at least a part of connection portion 111 and cut portion 142 including at least a part of connection portion 141.

[0043] If the signal wiring 110 is cut during pixel repair, it may affect the output of normal pixels 160 that share the signal wiring 110 with the pixel 160 to be repaired. Therefore, in the cut-out portion 112, at least a part of the connection portion 111 is cut so as to insulate the signal wiring 110 from the TFT 210, but the signal wiring 110 is not cut. At this time, it is preferable that the cut-out portion 112 does not include other conductive layers to prevent short circuits.

[0044] Furthermore, when the bias voltage is supplied only from one side of the pixel row, or when there are two or more pixels 160 to be repaired in one pixel row, cutting the bias wiring 140 may affect the output of normal pixels that share the bias wiring 140 with the pixel 160 to be repaired. Therefore, in the cutting portion 142, at least a part of the connection portion 141 is cut off so as to insulate the bias wiring 140 from the photoelectric conversion element 230, but the bias wiring 140 is not cut.

[0045] The cut-out portion 112 is a region where at least a part of the connection portion 111 between the TFT 210 and the signal wiring 110 of some of the pixels 160 is removed in order to insulate the TFT 210 and the signal wiring 110 of the some of the pixels 160. The cut-out portion 112 is an example of a removed portion. The some of the pixels are defective pixels.

[0046] The TFTs 210 of the other pixels of the plurality of pixels 160 are electrically connected to the signal wiring 110. The other pixels are normal pixels.

[0047] The cut-out portion 142 is a region where at least a part of the connection portion 141 between the photoelectric conversion element 230 and the bias wiring 140 of some pixels among the plurality of pixels 160 is removed in order to insulate the photoelectric conversion element 230 and the bias wiring 140 of the some pixels. The cut-out portion 142 is an example of a removed portion. The some pixels are defective pixels.

[0048] The photoelectric conversion elements 230 of the other pixels among the plurality of pixels 160 are electrically connected to the bias wiring 140. The other pixels are normal pixels.

[0049] Fig. 10(a) is a plan view showing a layout example of a pixel 160 having a different shape of the cutout portion 142 from that shown in Fig. 8(a). Figs. 10(b) and (c) are plan views of a repaired pixel obtained by performing pixel repair on the pixel 160 shown in Fig. 7(a). In the cutout portion 142, at least a part of the connection portion 141 is cut out so as to insulate the bias wiring 140 from the photoelectric conversion element 230, but the bias wiring 140 is not cut. In the cutout portion 142, a part of the bias wiring 140 may be cut out as long as the bias wiring 140 is not cut.

[0050] As described above, according to this embodiment, it is possible to achieve both reliable repair and a high aperture ratio in the following manner.

[0051] (1) Reliability of repair Of the six leak paths a to f that may occur in the pixel 160 in Fig. 1, there is a leak path c that cannot be repaired by the method shown in Fig. 2 and Fig. 3. In the pixel repair method of this embodiment shown in Fig. 8 and Fig. 10, by providing the cutout portions 112 and 142, all of the six leak paths a to f that may occur in the pixel 160 can be dealt with.

[0052] (2)Aperture ratio 2 and 3, in order to prevent a short circuit at the cut portion, the pixel is configured so that two or more conductive layers having different potentials do not overlap. Therefore, the photoelectric conversion element 230 cannot be provided at the portion to be repaired, and the aperture ratio decreases.

[0053] In this embodiment, a cut portion 142 of a part of the connection portion 141 is cut at a portion where two or more conductive layers overlap, but the conductive layers cut at the cut portion 142 have the same potential. Therefore, even if they are shorted during repair, a new short circuit does not occur because they are originally at the same potential. In addition, a lower electrode 235 having a different potential from the bias wiring 140 is also arranged under the repair portion of the connection portion 141. Since thick dense semiconductor layers 232 to 234 with a film thickness of about 1 μm are sandwiched between the lower electrode 235 and the bias wiring 140, damage is not applied during repair and the lower electrode 235 and the bias wiring 140 are not shorted. Therefore, in this embodiment, there is no cut portion 114 in FIG. 3, the length of the connection portion 131 can be shortened, and the connection portion 141 can be provided so as to overlap the photoelectric conversion element 230 in orthogonal projection, thereby increasing the aperture ratio.

[0054] According to this embodiment, it is possible to achieve both high reliability of repair in the pixel 160 and a high aperture ratio.

[0055] It should be noted that the above-described embodiments are merely illustrative of specific examples of implementing the present disclosure, and the technical scope of the present disclosure should not be interpreted as being limited by these embodiments. In other words, the present disclosure can be implemented in various forms without departing from its technical concept or main features.

[0056] The disclosure of this embodiment includes the following configuration. (Configuration 1) A plurality of pixels each including a photoelectric conversion element and a switching element; A bias line for supplying a bias voltage to the photoelectric conversion elements of the plurality of pixels; a first removal portion in which at least a part of a connection portion between a photoelectric conversion element of a part of the pixels among the plurality of pixels and the bias wiring is removed in order to insulate the photoelectric conversion element of the part of the pixels from the bias wiring; a bias wiring line electrically connected to photoelectric conversion elements of other pixels of the plurality of pixels; (Configuration 2) a signal wiring through which the electrical signals converted by the photoelectric conversion elements of the plurality of pixels are output via switching elements of the plurality of pixels; a second removed portion in which at least a part of a connection portion between the switching element of the special pixel and the signal wiring is removed in order to insulate the switching element of the special pixel from the signal wiring, 2. The radiation imaging device according to configuration 1, wherein the switching elements of the pixels in the other portion are electrically connected to the signal wirings. (Configuration 3) 3. The radiation imaging device according to configuration 1 or 2, wherein a connection portion between the photoelectric conversion element of the certain pixel and the bias wiring is provided at a position overlapping the photoelectric conversion element in orthogonal projection. (Configuration 4) The radiation imaging device according to any one of configurations 1 to 3, characterized in that at least a portion of the connection between the photoelectric conversion element of the some of the pixels and the bias wiring is provided inside a contact hole provided in an insulating film between the bias wiring and the photoelectric conversion element. (Configuration 5) 5. The radiation imaging device according to any one of configurations 1 to 4, wherein the photoelectric conversion element is not provided above the switching element. (Configuration 6) the part of pixels is a defective pixel, 6. The radiation imaging device according to any one of configurations 1 to 5, wherein the pixels in the other portion are normal pixels. (Configuration 7) A plurality of pixels each including a photoelectric conversion element and a switching element; A bias line for supplying a bias voltage to the photoelectric conversion elements of the plurality of pixels; a signal wiring through which the electrical signals converted by the photoelectric conversion elements of the plurality of pixels are output via switching elements of the plurality of pixels; A drive wiring for driving the switching element; a first connection portion that connects the switching element and the signal wiring; a second connection portion that connects the switching element and the drive wiring; a third connection portion that connects the switching element and the photoelectric conversion element; A radiation imaging device, wherein a length of the first connection portion is longer than a length of the second connection portion and a length of the third connection portion. (Configuration 8) Further comprising a fourth connection portion that connects the photoelectric conversion element and the bias wiring, 8. The radiation imaging device according to configuration 7, wherein the fourth connection portion is provided at a position overlapping the photoelectric conversion element in orthogonal projection. (Configuration 9) 9. The radiation imaging device according to configuration 8, wherein at least a part of the fourth connection portion is provided inside a contact hole provided in an insulating film between the bias line and the photoelectric conversion element. (Configuration 10) 10. The radiation imaging device according to any one of configurations 7 to 9, wherein the photoelectric conversion element is not provided above the switching element. [Explanation of symbols]

[0057] REFERENCE SIGNS LIST 1 radiation imaging device, 10 readout circuit, 20 drive circuit, 30 power supply unit, 40 control and calculation unit, 50 memory, 60 sensor substrate, 160 pixel, 210 TFT, 230 photoelectric conversion element, 110 signal wiring, 120 drive wiring, 140 bias wiring

Claims

1. A plurality of pixels each including a photoelectric conversion element and a switching element; A bias line for supplying a bias voltage to the photoelectric conversion elements of the plurality of pixels; a first removal portion in which at least a part of a connection portion between a photoelectric conversion element of a part of the pixels among the plurality of pixels and the bias wiring is removed in order to insulate the photoelectric conversion element of the part of the pixels from the bias wiring; a bias wiring line electrically connected to photoelectric conversion elements of other pixels of the plurality of pixels;

2. a signal wiring through which the electrical signals converted by the photoelectric conversion elements of the plurality of pixels are output via switching elements of the plurality of pixels; a second removed portion in which at least a part of a connection portion between the switching element of the special pixel and the signal wiring is removed in order to insulate the switching element of the special pixel from the signal wiring, 2. The radiation imaging apparatus according to claim 1, wherein the switching elements of the pixels of the other portion are electrically connected to the signal wirings.

3. 2. The radiation imaging apparatus according to claim 1, wherein a connection portion between the photoelectric conversion element of the part of pixels and the bias wiring is provided at a position overlapping the photoelectric conversion element in an orthogonal projection.

4. 2. The radiation imaging device according to claim 1, wherein at least a portion of a connection between the photoelectric conversion element of the certain pixel and the bias wiring is provided inside a contact hole provided in an insulating film between the bias wiring and the photoelectric conversion element.

5. 2. The radiation imaging apparatus according to claim 1, wherein the photoelectric conversion element is not provided above the switching element.

6. the part of pixels is a defective pixel, 2. The radiation imaging apparatus according to claim 1, wherein the pixels in the other portion are normal pixels.

7. A plurality of pixels each including a photoelectric conversion element and a switching element; A bias line for supplying a bias voltage to the photoelectric conversion elements of the plurality of pixels; a signal wiring through which the electrical signals converted by the photoelectric conversion elements of the plurality of pixels are output via switching elements of the plurality of pixels; A drive wiring for driving the switching element; a first connection portion that connects the switching element and the signal wiring; a second connection portion that connects the switching element and the drive wiring; a third connection portion that connects the switching element and the photoelectric conversion element, A radiation imaging apparatus, wherein a length of the first connection portion is longer than a length of the second connection portion and a length of the third connection portion.

8. Further, a fourth connection portion is provided to connect the photoelectric conversion element and the bias wiring, The radiation imaging apparatus according to claim 7 , wherein the fourth connection portion is provided at a position overlapping with the photoelectric conversion element in an orthogonal projection.

9. 9. The radiation imaging apparatus according to claim 8, wherein at least a part of the fourth connection portion is provided inside a contact hole provided in an insulating film between the bias wiring and the photoelectric conversion element.

10. 8. The radiation imaging apparatus according to claim 7, wherein the photoelectric conversion element is not provided above the switching element.

Images