JP2012199551A - Radiation detecting apparatus, radiation imaging apparatus and radiation imaging system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a radiation detecting apparatus for lowering parasitic capacity of signal wiring and gate wiring, improving sensitivity and reducing noise.SOLUTION: The radiation detecting apparatus comprises: pixels including switching elements arranged on an insulating substrate and conversion elements arranged on the switching elements to convert radiation into electric charges, for which the switching elements and the conversion elements are connected and the pixels are two-dimensionally arrayed on the insulating substrate in a matrix; gate wiring commonly connected with the plurality of switching elements arranged in a row direction on the insulating substrate; and signal wiring commonly connected with the plurality of switching elements arranged in a column direction. A plurality of insulating films are arranged between the switching elements and the conversion elements, and at least one of the gate wiring and the signal wiring is arranged to be held between the plurality of insulating films.

Description

  The present invention relates to a radiation detection apparatus having a conversion element for converting radiation into electric charge and a thin film transistor (TFT) as a switching element in a pixel.

  This radiation detection apparatus is particularly preferably used for a radiation detection apparatus for detecting radiation, and is applied to medical image diagnostic apparatuses, nondestructive inspection apparatuses, analysis apparatuses using radiation, and the like. Here, in this specification, in addition to α-rays, β-rays, γ-rays, and the like, which are beams generated by particles (including photons) emitted by visible light or radiation decay, a beam having the same or higher energy, For example, X-rays, particle beams, and cosmic rays are also included in the radiation.

  In recent years, TFT matrix panels in which TFTs are formed on an insulating substrate have been rapidly increased in size and driving speed. A manufacturing technique of a liquid crystal panel using TFT is used for an area sensor (for example, a radiation detection apparatus) having a semiconductor conversion element that converts radiation such as X-rays into an electric signal. As such a semiconductor conversion element, for example, a wavelength conversion layer (for example, a phosphor layer) for wavelength conversion from radiation such as X-rays to light such as visible light is disposed on the surface, and photoelectric conversion of this light, Some use a semiconductor conversion material that directly performs photoelectric conversion.

  In a substrate that reads such a semiconductor conversion element and a TFT for reading out an electrical signal from the semiconductor conversion element in a two-dimensional manner and reads the radiation dose, the radiation irradiated to each pixel or the light converted from the radiation The amount of light is detected. By detecting more light, it is possible to provide a highly sensitive radiation detection device. To that end, while maintaining the performance of the TFT, the semiconductor conversion elements are arranged using the entire space effectively. There is a need.

  For this reason, conventionally, after a TFT array is formed, a semiconductor conversion element is stacked on the TFT array to prevent loss of aperture ratio due to the TFT and improve sensitivity. As an example, Patent Document 1 describes that a semiconductor conversion element is disposed on top of a TFT.

  A planarization layer is formed on the source electrode and the drain electrode of the TFT, and a semiconductor conversion element is formed thereon. By providing the planarization layer, it becomes possible to provide the semiconductor conversion element on the TFT and each wiring by reducing the capacitive coupling between the TFT and the semiconductor conversion element. With this configuration, the aperture ratio of the semiconductor conversion element is improved.

JP 2004-015002 A

  However, for example, in the moving image shooting sensor of the radiation detection apparatus, it is necessary to accurately read a minute signal from the semiconductor conversion element because shooting is performed in a region where the radiation dose is very small. Therefore, it is necessary to further increase the S / N ratio of the radiation detection apparatus. Increasing the aperture ratio of the semiconductor conversion element and increasing the sensitivity can be achieved by, for example, using a planarization layer and providing the semiconductor conversion element on the top. Therefore, in order to further improve the S / N ratio, it is necessary to further reduce the noise. Therefore, it is required to further reduce the capacity of the signal wiring and the gate wiring.

  The present invention reduces the parasitic capacitance between the signal wiring and the gate wiring in the radiation detection device in which the pixels in which the conversion elements for converting the radiation into electric charges and the switch elements are paired are two-dimensionally arranged, and the sensitivity Improvement of noise and reduction of noise. Further, the parasitic capacitance between the conversion element and the wiring is reduced to improve sensitivity and reduce noise. In addition, in the case of high-speed moving image shooting that performs high-speed driving, a radiation detection apparatus with a high S / N ratio that can obtain a good image even if the level of incident radiation is low is provided.

In order to solve the above problems, the radiation detection apparatus of the present invention is:
A switch element having a gate electrode disposed on an insulating substrate; and a source electrode and a drain electrode disposed on a gate insulating layer covering the gate electrode; and one of the source electrode and the drain electrode of the switch element Connected to the conversion element for converting the radiation arranged on the switch element into electric charge, the gate wiring connected to the gate electrode of the switch element, and the other of the source electrode and the drain electrode of the switch element A radiation detection device having a signal wiring arranged to intersect the gate wiring, wherein a plurality of insulating layers are arranged between the switch element and the conversion element, and the gate wiring and the signal wiring At least one is a metal layer having a melting point lower than that of the gate electrode and a small specific resistance, which is disposed between the plurality of insulating layers. It is characterized in.

  Note that in this specification, a conversion element that converts radiation into electric charge refers to receiving radiation such as X-rays, α-rays, β-rays, and γ-rays from light such as visible light and infrared light, and converting these into electric charges. An element to be converted. It includes a photoelectric conversion element that converts light such as visible light and infrared light into electric charges, and an element that directly converts radiation such as X-rays having amorphous selenium or the like as a semiconductor layer into electric charges.

  According to the present invention, by arranging one of the signal wiring and the gate wiring between the two insulating layers, it is possible to reduce the capacitance of the wiring, reduce artifacts, and provide a low-noise radiation detection apparatus. Furthermore, the number of signal lines and gate lines can be increased, and the number of signals obtained simultaneously when the gate lines are driven at a time can be increased. As a result, in the case of high-speed moving image shooting, it is possible to obtain an accurate image when imaged even in the case of a low radiation dose region or a low light amount.

It is a top view of a pixel of a radiation detection device concerning a first embodiment of the present invention. It is sectional drawing along the AA 'line of FIG. 1 is a simplified equivalent circuit diagram of a radiation imaging apparatus according to a first embodiment of the present invention. It is a top view of the pixel of the radiation detection apparatus which concerns on 2nd embodiment of this invention. FIG. 5 is a cross-sectional view taken along line BB ′ in FIG. 4. FIG. 6 is a simplified equivalent circuit diagram of the radiation imaging apparatus of FIGS. 4 and 5 according to the present invention. It is the top view of the pixel of the radiation detection apparatus which concerns on 2nd embodiment of this invention, and is the figure which showed the example different from FIG. FIG. 8 is a cross-sectional view taken along the line CC ′ of FIG. 7. It is the top view of the pixel of the radiation detection apparatus which concerns on 2nd embodiment of this invention, and is the figure which showed the example different from FIG. 4, FIG. FIG. 10 is a simplified equivalent circuit diagram of the radiation imaging apparatus of FIG. 9 according to the present invention. It is a top view of the pixel of the radiation detection apparatus which concerns on 3rd embodiment of this invention. It is sectional drawing along the D-D 'line of FIG. It is a simple equivalent circuit diagram of the radiation imaging device which concerns on 3rd embodiment of this invention. It is sectional drawing along the AA 'line similarly to FIG. 1 concerning 4th embodiment of this invention. It is sectional drawing in the boundary part of the area | region where the 1st, 2nd insulating layer shown in FIG. 14 is arrange | positioned, and the area | region which is not arrange | positioned. It is a top view of the pixel of the radiation detection instrument concerning a 5th embodiment of the present invention. It is sectional drawing along the EE 'line of FIG. It is a simple equivalent circuit schematic of the radiation imaging device which concerns on the 6th embodiment of this invention. It is a conceptual diagram which shows the relationship between the pixel area | region in the board | substrate of a radiation imaging device and the peripheral circuit which concern on 6th embodiment of this invention. FIG. 14 is a simplified equivalent circuit diagram of a radiation imaging apparatus according to a sixth embodiment of the present invention, illustrating an example different from FIG. 13. It is a top view of a pixel of a radiation detecting device concerning a 6th embodiment of the present invention. FIG. 22 is a sectional view taken along line FF ′ in FIG. 21. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic configuration diagram of a mounting example of a radiation (X-ray) imaging apparatus according to the present invention, (a) is a plan view, and (b) is a cross-sectional view. It is the figure which showed the application example to the radiation imaging system of the radiation imaging device by this invention. It is a top view of the pixel of the radiation detection instrument concerning an 8th embodiment of the present invention. It is sectional drawing along the GG 'line | wire in FIG.

  Hereinafter, embodiments of the present invention will be specifically described with reference to the accompanying drawings. Although the following embodiment demonstrates the case where a radiation detection apparatus is comprised, the radiation detection apparatus of this invention is not limited to the radiation detection apparatus which converts radiations, such as X-rays, alpha rays, and gamma rays, into an electric charge, but visible The present invention can also be applied as a photoelectric conversion device that converts light such as light and infrared light into an electrical signal. Note that the radiation imaging apparatus is an apparatus including a sensor substrate and a peripheral circuit that can be regarded as a radiation detection apparatus.

(First embodiment)
First, a first embodiment of the present invention will be described.

  1 to 3 are a plan view, a cross-sectional view, and a simplified equivalent circuit diagram of a pixel of the radiation detection apparatus according to the first embodiment of the present invention.

  The main point of this embodiment is that a plurality of insulating layers are arranged between the switch element and the conversion element, and at least one of the gate wiring and the signal wiring is arranged in a region sandwiched between the insulating layers. That is. This point is common to all the embodiments.

  FIG. 1 is a plan view of a pixel of the radiation detection apparatus according to the first embodiment of the present invention.

  Plane layout diagram showing a pixel portion of 2 rows × 2 columns in an effective pixel region in which pixels that are paired with a conversion element that converts radiation into an electrical signal (charge) and a switch element are arranged in a matrix on an insulating substrate It is.

  The conversion element of this embodiment is a semiconductor conversion element using, for example, hydrogenated amorphous silicon, which converts light such as visible light and infrared light, and radiation such as X-rays and γ-rays into electric charges. When a photoelectric conversion element that does not directly convert radiation such as X-rays, for example, converts light such as visible light into an electrical signal, is used as the semiconductor conversion element, the radiation can be photoelectrically converted into visible light or the like above it. A phosphor layer is disposed as a wavelength conversion layer (scintillator) that converts light.

  In FIG. 1, a TFT that is a switch element includes three electrodes: a source electrode 123 that is one electrode, a drain electrode 124 that is the other electrode, and a gate electrode 136. A signal wiring 121 connected to a signal processing circuit unit that reads the accumulated electric charge is connected to a source electrode 123 of the TFT. Further, the gate wiring 122 connected to the gate driver circuit portion for controlling ON or OFF of the TFT is connected to the gate electrode 136 of the TFT. A TFT channel portion 125 exists between the source electrode 123 and the drain electrode 124, and by controlling the voltage of the gate electrode 136, the charge can be controlled to flow or stop in the channel portion 125.

  The gate wiring 122 is commonly connected to TFTs of a plurality of pixels arranged in the row direction, and the signal wiring 121 is commonly connected to TFTs of a plurality of pixels arranged in the column direction.

  Here, the row direction and the column direction are convenient expressions that come from a plurality of pixels arranged in a two-dimensional matrix, and the positions of the rows and columns may be interchanged. That is, the gate wiring 122 may be in the column direction and the signal wiring 121 may be in the row direction.

  The semiconductor conversion element includes a lower electrode 126, a light receiving region 128, and a bias wiring 127, and is disposed on the upper surface of the TFT. The lower electrode 126 is connected to the drain electrode 124 through a through hole.

  The signal wiring 121 is disposed under the lower electrode 126, and is further connected to the source electrode 123 disposed therebelow through a through hole. However, the lower electrode 126 and the signal wiring 121 of the semiconductor conversion element do not need to overlap two-dimensionally as shown in FIG. 1, and may be arranged so as not to overlap as necessary. The signal wiring 121 is disposed so as to be sandwiched between an insulating layer disposed under the lower electrode 126 and an insulating layer covering the TFT portion such as the source electrode and the drain electrode.

  FIG. 2 is a cross-sectional view taken along the line AA ′ of FIG. 1. The upper part shows a semiconductor conversion element, the lower part shows a TFT, and the wiring is arranged above the source or drain electrode in order to reduce the capacitance of the signal wiring. This is an example of arrangement in a region sandwiched between a first insulating layer and a second insulating layer.

  The upper semiconductor conversion element includes a fourth metal layer 108, an insulating layer 110 of the semiconductor conversion element, a second high-resistance semiconductor layer 111, a second impurity semiconductor layer 112 that is an ohmic contact layer, and a transparent electrode layer 113. This is a MIS type semiconductor conversion element. This semiconductor conversion element can photoelectrically convert light such as visible light. The lower TFT portion has the following configuration. A first metal layer 101 disposed on an insulating substrate. A gate insulating layer 102 disposed on the first metal layer 101; A first high-resistance semiconductor layer 103 disposed on the gate insulating layer 102; A first impurity semiconductor layer 104 disposed on the first high-resistance semiconductor layer 103; It consists of a second metal layer 105 disposed on the first impurity semiconductor layer 104. A first insulating layer 106 and a second insulating layer 109 are disposed between the TFT portion and the semiconductor conversion element, and a third metal layer 107 is disposed on the second metal layer 105. A phosphor layer 116 is disposed on the protective layer 117.

  A transparent electrode layer 113 made of, for example, ITO is disposed on the second impurity semiconductor layer 112. If the resistance of the second impurity semiconductor layer 112 is low, the second impurity semiconductor layer 112 is It can also serve as an electrode layer, and the transparent electrode layer 113 is not necessary. The fifth metal layer 114 is a bias wiring for applying a voltage to the transparent electrode layer, and is connected to a common electrode driver arranged outside the substrate. Here, the fifth metal layer 114 is disposed in contact with the upper portion of the transparent electrode layer 113, but the fifth metal layer 114 may be disposed so as to be covered by the transparent electrode layer 113. Further, the bias wiring may be arranged anywhere in the pixel. However, in the case of a semiconductor conversion element that converts radiation into visible light and converts the visible light into electric charge in the second high-resistance semiconductor layer, the fourth metal layer that is the lower electrode of the semiconductor conversion element is not disposed. It is further preferable that light is received over the entire region where charges are easily collected by placing the region.

  The signal wiring 121 shown in FIG. 1 is formed of the third metal layer 107 of FIG. 2 and is arranged in a region sandwiched between the first insulating layer 106 and the second insulating layer 109. . Here, when the first insulating layer 106 and the second insulating layer 109 are, for example, a film having a small film thickness and a high relative dielectric constant, a semiconductor conversion element including the fourth metal layer 108 disposed on the upper part is used. A large capacitance is formed between the lower electrode. Further, a large capacitance is formed at the intersection with the gate wiring (not shown) connected to the gate electrode made of the first metal layer 101. Therefore, it is desirable that the first insulating layer 106 and the second insulating layer 109 can be formed thick and have a low dielectric constant. In this embodiment, an insulating layer made of an organic material having a low relative dielectric constant is used. The organic material is preferably a material having high heat resistance such as polyimide resin or acrylic resin, and a relative dielectric constant of about 2.5 to 4 is preferable. The thickness of the insulating layer made of an organic material is desirably 1 μm or more even in a thin region. However, among inorganic materials, for example, silicon oxide having a relative dielectric constant of relatively low, such as a relative dielectric constant of about 3.5 to 4.5, and nitriding excellent in insulation with a relative dielectric constant of about 5.5 to 7.5. The silicon film may be formed thick. Thereby, it is possible to reduce the capacity of the gate wiring intersecting with the signal wiring and the capacity of the semiconductor conversion element and the signal wiring arranged on the upper part.

  At the same time, since an insulating layer made of, for example, the above-described organic material is disposed at the intersection of the signal wiring and the gate wiring, the capacitance can be greatly reduced. Further, a signal wiring 121 is disposed in a region sandwiched between the first insulating layer 106 and the second insulating layer 109. This is because the capacitance formed by the gate wiring 122 and the signal wiring 121 can be reduced even in the gate wiring 122 shown in FIG. 1, and the capacitance applied to the semiconductor conversion element can also be reduced. When the gate wiring 122 is disposed as a third metal layer 107 in a region between the first insulating layer 106 and the second insulating layer 109, the gate wiring 122 is disposed from the first metal layer 101 through a through hole. At this time, the signal wiring 121 is formed of the same metal layer as the source or drain electrode of the TFT.

  When an insulating layer made of an organic material is used, for example, a photosensitive polyimide resin or a photosensitive acrylic resin is used, (1) formation of an organic material insulating layer, (2) exposure, (3) development removal, and (4) baking. , It can be easily formed. Alternatively, a process may be used in which patterning is performed using a photolithography method using a photosensitive resist on the upper portion, and removal is performed, for example, by dry etching.

  In FIG. 2, the upper semiconductor conversion element is described as a MIS type semiconductor conversion element. However, a PIN type semiconductor conversion element including an n type semiconductor layer, a second high resistance semiconductor layer, and a p type semiconductor layer is used. Also good. At this time, the same applies to the case of a PIN semiconductor conversion element. When the resistance of a p-type semiconductor layer or an n-type semiconductor layer is low, it can also serve as an electrode layer. Further, amorphous selenium or cadmium tellurium that directly photoelectrically converts radiation into the semiconductor conversion element may be used.

  FIG. 3 is a simplified equivalent circuit diagram of the radiation imaging apparatus shown in FIGS. 1 and 2.

  It is composed of pixels arranged in a matrix, a substrate including a number of gate wirings or signal wirings corresponding to each row or column, and a signal processing circuit unit, a gate driver circuit unit, and a common electrode driver circuit unit arranged around the periphery. It is an example of a radiation imaging device. In the pixel, a semiconductor conversion element and a TFT are paired.

  In the substrate 160, pixels that form pairs of TFT portions 152 and semiconductor conversion element portions 153 that are switching elements are arranged in a matrix. A gate wiring 154 and a signal wiring 155 are connected to the TFT portion 152, and a bias wiring 157 from the common electrode driver circuit portion 156 is connected to the semiconductor conversion element portion 153.

  The signal wiring 155 is connected to S <b> 1 to S <b> 6 of the signal processing circuit unit 150 disposed outside the substrate 160, and is imaged by reading charges generated in the semiconductor conversion element unit 153 through the TFT. Similarly, the gate wiring 154 is connected to a gate driver circuit unit 151 disposed outside the substrate 160, and the gate electrode voltage is controlled by G1 to G6 to control ON / OFF of the TFT. The common electrode driver circuit unit 156 controls the voltage applied to the semiconductor conversion element, and applies a voltage to the high resistance semiconductor layer in the semiconductor conversion element. At this time, for example, a depletion bias or an accumulation bias can be selected, or the strength of the applied voltage can be changed to control the electric field strength. In particular, when the MIS type semiconductor conversion element is used, it is necessary to control the voltage in order to remove holes or electrons accumulated at the interface between the insulating film and the high resistance semiconductor layer after reading out the charges. At 156.

  In FIG. 3, the bias wiring 157 is disposed at the center of the semiconductor conversion element portion, but as shown in FIG. 2, the fourth metal layer 108 that is the lower electrode of the semiconductor conversion element is not actually disposed. It should be in the area.

  Two signal processing circuit units 150 and two gate driver circuit units 151 may be arranged on the left and right, respectively. When the signal processing circuit units are arranged vertically, the signal wiring may be divided at the center, for example, and the upper half signal may be controlled by the upper signal processing circuit unit and the lower half signal may be controlled by the lower signal processing circuit unit. Absent. When the gate driver circuit portions are arranged on the left and right, the gate wiring may be divided at the center or may remain connected.

(Second embodiment)
A second embodiment of the present invention will be described.

  4 to 10 are a plan view, a cross-sectional view, and a simplified equivalent circuit diagram of the radiation imaging apparatus of the radiation detection apparatus according to the second embodiment of the present invention.

  The main point of this embodiment is that a plurality of signal wirings are arranged for a plurality of pixels in one column, the plurality of pixels in one column are sequentially allocated to each signal wiring, and connected to the thin film transistor of the pixel to which each signal wiring is allocated. It is that it has been.

  FIG. 4 is a plan view of a pixel of the radiation detection apparatus according to the second embodiment of the present invention.

  It is a plane layout diagram showing a pixel portion of 2 rows × 2 columns in an effective pixel region in which pixels in which a conversion element that converts radiation into an electrical signal and a switch element are paired are arranged in a matrix on an insulating substrate. Four signal wires are arranged. The pixels in one column are sequentially divided into two and correspond to the two signal wiring lines.

  The semiconductor conversion element of this embodiment is also a semiconductor element that converts radiation into an electric signal. When a photoelectric conversion element that converts light such as visible light into an electric signal is used, a phosphor layer is disposed on the photoelectric conversion element.

  A TFT that is a switch element will be described. One is a TFT composed of three electrodes, a first source electrode 131, a first drain electrode 132, and a first gate electrode 138, which are arranged on an insulating substrate. The other is a TFT composed of three electrodes: a second source electrode 133, a second drain electrode 134, and a second gate electrode 139. There are two types of TFTs. The pixels in each column are sequentially divided into two, and two signal wirings connected to the signal processing circuit unit that reads and processes the accumulated charges are arranged in each column. That is, the first signal wiring 129 connected to the first source electrode 131 and the second signal wiring 130 connected to the second source electrode 133 are separated. In addition, the gate driver circuit portion for controlling ON or OFF of the TFT includes a first gate wiring 140 connected to the first gate electrode 138 and a second gate wiring connected to the second gate electrode 139. 141. A TFT channel portion 125 exists between each source electrode and drain electrode, and by controlling the voltage of each gate electrode, it is possible to control whether charges flow or stop in the channel portion.

  The semiconductor conversion element includes a lower electrode 126, a light receiving region 128, and a bias wiring 127, and is disposed on the upper surface of the TFT. Of the lower electrodes 126, two lower electrodes arranged on the upper side in the drawing are connected to the first drain electrode 132 through a through hole, and two lower electrodes arranged on the lower side in the drawing are connected to the first drain electrode 132 through the through hole. The second drain electrode 134 is connected.

  After the radiation is irradiated and charges are accumulated in the pixel in accordance with the irradiation amount, information is transferred to the signal processing circuit section via the TFT and imaged. At this time, the signal wiring is separated into two systems in order to increase the number of signals that can be transferred at one time. In FIG. 4, the signal wiring connected to the first source electrode 131 of the TFT connected to the first gate wiring 140 is a first signal wiring 129. A signal wiring connected to the second source electrode 133 of the TFT connected to the second gate wiring 141 is a second signal wiring 130. The first gate wiring 140 and the second gate wiring 141 are connected within the substrate in front of the gate driver circuit portion, and can be driven simultaneously. When the on-voltage of the TFT is applied to both gate wirings simultaneously, the four TFTs shown in FIG. 4 are simultaneously turned on, and the first signal wiring 129 and the second signal wiring 130 are both four in total. Electric charges can be read simultaneously from the signal wiring.

  In this figure, each signal wiring is arranged under the lower electrode 126, and further connected to each source electrode arranged therebelow through a through hole. Each signal wiring is arranged in such a manner that it is sandwiched between an insulating layer arranged under the lower electrode 126 and an insulating layer covering the TFT portion such as each source electrode and each drain electrode.

  FIG. 5 is a cross-sectional view taken along the line BB ′ of FIG. 4. The upper part shows a semiconductor conversion element, the lower part shows a TFT, and the wiring is arranged above the source or drain electrode in order to reduce the capacity of the signal wiring. This is an example of arrangement in a region sandwiched between a first insulating layer and a second insulating layer.

  A description of parts common to those in FIG. 2 is omitted.

  The upper semiconductor conversion element includes a fourth metal layer 108, an insulating layer 110 of the semiconductor conversion element, a second high-resistance semiconductor layer 111, a second impurity semiconductor layer 112 that is an ohmic contact layer, and a transparent electrode layer 113. This is a MIS type semiconductor conversion element. It is possible to photoelectrically convert light such as visible light. The fifth metal layer 114 is a bias wiring for applying a voltage to the transparent electrode layer, and is connected to a common electrode driver arranged outside the substrate.

  Each signal wiring 129 and 130 shown in FIG. 4 is formed of the third metal layer 107 of FIG. 5 and is arranged in a region sandwiched between the first insulating layer 106 and the second insulating layer 109. Has been. Here, the first insulating layer 106 and the second insulating layer 109 are desirably thick and have a low dielectric constant. In this embodiment, an insulating layer made of an organic material having a low relative dielectric constant is used. The organic material is preferably a material having high heat resistance such as polyimide resin or acrylic resin, and a relative dielectric constant of about 2.5 to 4 is preferable. The thickness of the insulating layer made of an organic material is desirably 1 μm or more.

  As a result, as shown in FIG. 4, even if the signal wiring is divided into two systems and the number of signal wirings is doubled as usual, the capacity of each gate wiring intersecting with these signal wirings and the semiconductor disposed on the upper part It is possible to prevent the capacitance between the conversion element and each signal wiring from increasing. As a result, it is possible to increase the number of signals that can be simultaneously captured without increasing the time constant in the gate wiring composed of the capacitance and resistance of the gate wiring, so that a radiation imaging apparatus that can be driven at high speed is provided. be able to.

  Further, in FIG. 5, the upper semiconductor conversion element has been described as a MIS type semiconductor conversion element. Similarly, a PIN type semiconductor conversion element may be used, or amorphous selenium that directly photoelectrically converts radiation into the semiconductor conversion element. Or cadmium tellurium may be used.

  FIG. 6 is a simplified equivalent circuit diagram of the radiation imaging apparatus shown in FIGS. 4 and 5.

  Pixels are arranged in a matrix, a gate wiring corresponding to the number of rows, a substrate including signal wiring twice as many as the number of columns, a signal processing circuit unit, a gate driver circuit unit arranged around, a common It is an example of the radiation imaging device which consists of an electrode driver circuit part. In the pixel, a semiconductor conversion element and a TFT are paired.

  In the substrate 160, pixels that form pairs of TFT portions 152 and semiconductor conversion element portions 153 that are switching elements are arranged in a matrix. A gate wiring 154 and a signal wiring 155 are connected to the TFT portion 152, and a bias wiring 157 from the common electrode driver circuit portion 156 is connected to the semiconductor conversion element portion 153. The gate lines g11 and g12, g21 and g22, g31 and g32 are connected to each other, and can be controlled from the gate driver circuit unit 151 by three lines G1 to G3. For example, when a TFT on-voltage is applied to G1, the TFT on-voltage is simultaneously applied to the gate wirings of g11 and g12. At this time, in the signal processing circuit unit 150, both the signal wirings s12, s22, s32... By the TFT connected to g11 and the signal wirings s11, s21, s31. At the same time, the charge can be read. For this reason, high-speed driving can be performed.

  FIG. 7 is a plan view of a pixel of the radiation detection apparatus according to the second embodiment, and is a plan layout diagram of the pixel showing an example different from FIG.

  The difference from FIG. 4 is that the light receiving region of the semiconductor conversion element arranged at the top is arranged avoiding at least a part of the source electrode, drain electrode and gate electrode of the TFT and the channel portion.

  As an example, the difference is that a light receiving region opening 137 is provided, and that each source electrode and each drain electrode are formed larger. In the TFT manufacturing process, defects occur with a certain probability. At this time, the TFT portion is evaporated by, for example, laser light and electrically separated, thereby preventing the influence of defective pixels. At this time, information on the defective pixel portion can be dealt with by performing correction using surrounding information. At this time, it is necessary to remove in advance a light receiving region that easily absorbs light in order to quickly find a defective portion and expose each source electrode and each drain electrode to be evaporated.

  FIG. 8 is a cross-sectional view taken along the line CC ′ of FIG.

  The upper part shows a semiconductor conversion element and the lower part shows a TFT, and in order to reduce the capacitance of the signal wiring, the wiring is arranged in a region between the first insulating layer and the second insulating layer above the source or drain electrode. In this example, the light receiving region above the TFT is opened.

  A description of portions common to FIG. 5 is omitted.

  The second high-resistance semiconductor layer 111 that is particularly easy to absorb light disposed on the TFT is removed only directly above the TFT. At this time, the insulating layer 110 of the semiconductor conversion element is not removed, but may be removed at the same time as the second high-resistance semiconductor layer 111. By adopting such a configuration, for example, before placing the phosphor layer on the protective layer 117, the defective portion is evaporated using a laser beam, and then the phosphor layer is formed, thereby increasing the yield. It can be secured.

  Further, as shown in FIG. 5, when the second high resistance semiconductor layer 111 is disposed on the entire surface, when a part is evaporated by a laser beam in order to repair a defect, the second high resistance semiconductor layer 111 is formed. Defects will affect the surroundings. Therefore, it is necessary to remove the second high-resistance semiconductor layer in the entire region to which the laser light is applied. Such a configuration is the same not only in the case of the MIS type semiconductor conversion element but also in the case of the above-described PIN type semiconductor conversion element, and also in the case where a direct conversion material is used. In FIG. 8, the second high-resistance semiconductor layer 111 is removed only in substantially the same region as the portion where the gate electrode made of the first metal layer 101 is disposed, but stably irradiates the laser beam. For this purpose, it is desirable that the opening be made in a region slightly wider than the first metal layer 101.

  FIG. 9 is a plan view of a pixel of the radiation detection apparatus according to the second embodiment.

  FIG. 8 is a plan layout diagram of a pixel showing an example different from FIGS. 4 and 7. This is an effective pixel area in which pixels paired with TFTs and semiconductor conversion elements are arranged in a matrix, and a pixel portion of 3 rows × 2 columns. The difference from FIG. 4 is that six signal wirings are arranged. It is a point. The pixels in one column are sequentially divided into three and correspond to the three signal wiring lines.

  Three signal wirings are arranged in one column, the first signal wiring 129, the second signal wiring 130, and the third signal wiring 135, and six pixels are arranged in a matrix of 3 rows × 2 columns. The difference is that the signal wiring is provided. Further, three gate wirings, that is, a first gate wiring 140, a second gate wiring 141, and a third gate wiring 142 are arranged. Each signal wiring shown in FIG. 9 is arranged in a region sandwiched between organic materials having a low relative dielectric constant, and the capacitance generated between the surrounding wiring and the upper semiconductor conversion element is reduced. Can do. As a result, even if the signal wiring is divided into three systems and the number of signal wirings is three times the normal number, it is possible to prevent the capacity of each gate wiring intersecting with these signal wirings from increasing. In addition, since the number of TFTs connected to one signal wiring is reduced, the capacitance formed between the source electrode and the gate electrode of the TFT portion is reduced, and the total capacitance of the signal wiring is also reduced. Can do.

  As a result, the degree of freedom of the routing method of each wiring is increased, and a plurality of wirings can be routed in the pixels arranged in one row or column. In addition, the number of signals that can be simultaneously captured can be increased without increasing the time constant in the gate wiring composed of the capacitance and resistance of the gate wiring. Therefore, it is possible to provide a radiation detection apparatus that can be driven at a higher speed. In FIG. 9, three times as many signal wirings as usual are arranged, but multiple times signal wirings may be arranged, such as four times or five times. Further, when the capacitance between the gate wiring and the signal wiring occupies a large proportion in the TFT portion, with this structure, the number of TFTs connected to one gate wiring or signal wiring is 1/4, 1 / As a result, the capacity of each wiring is further reduced.

  FIG. 10 is a conceptual diagram of a simple equivalent circuit and peripheral circuits of the radiation imaging apparatus shown in FIG.

  Pixels are arranged in a matrix, a gate wiring corresponding to the number of rows, a substrate including three times the number of columns of signal wirings, a signal processing circuit unit and a gate driver circuit unit arranged around It is an example of the radiation imaging device which consists of an electrode driver circuit part. In the pixel, a semiconductor conversion element and a TFT are paired.

  In the substrate 160, pixels that form pairs of TFT portions 152 and semiconductor conversion element portions 153 that are switching elements are arranged in a matrix. A gate wiring 154 and a signal wiring 155 are connected to the TFT portion 152, and a bias wiring 157 from the common electrode driver circuit portion 156 is connected to the semiconductor conversion element portion 153. The gate wirings g11 to g13 and g21 to g23 are connected to each other in three, and can be controlled from the gate driver circuit unit 151 by two wirings G1 and G2. For example, when the TFT on-voltage is applied to G1, the TFT on-voltage is simultaneously applied to the gate wirings of g11, g12, and g13. At this time, the charge can be read simultaneously for three rows. The first row is from signal wirings s12, s22, s32... By TFTs connected to g11. The second row is from signal wirings s11, s21, s31... By TFTs connected to g12. The third row is from signal wirings s13, s23, s33,... By TFTs connected to g13. Electric charges can be read simultaneously from all of these signal wirings in the signal processing circuit unit 150. For this reason, high-speed driving can be performed.

  Also in the radiation detection apparatus having such a configuration, an increase in capacitance can be reduced by arranging the signal wiring in the region sandwiched between the first insulating layer 106 and the second insulating layer 109 as described above. Accordingly, it is possible to route wiring with a high degree of freedom, change the wiring routing method, and provide a low-noise radiation detection apparatus that supports high-speed moving images.

(Third embodiment)
11 to 13 are a plan view of a pixel of a radiation detection device and a simplified equivalent circuit diagram of the radiation imaging device according to a third embodiment of the present invention.

  In the third embodiment, there is provided a radiation detection apparatus capable of moving image shooting, in which two transistors are arranged in one pixel so as to enable high-speed driving. The main point of this embodiment is that a pixel in which one semiconductor conversion element and two TFTs are paired is two-dimensionally arranged. For example, one TFT is used for charge transfer and the other TFT is used for resetting. It is a point to do. According to this embodiment, for example, it is possible to reset a pixel that has finished transferring charges at the same time as transferring charges from a specific pixel.

  In the case of forming a pixel having such a configuration, in the conventional configuration, the number of gate wirings connected to the TFT is twice that when there is no reset TFT. For this reason, the number of gate lines intersecting with the signal lines increases, and the capacity of the signal lines increases. When a radiation detection apparatus is driven at a high speed to obtain a moving image, it is necessary to reduce the radiation dose to the limit in order to reduce the exposure dose of the object. However, as the capacity of the signal wiring increases, the noise of the detection device increases, the image quality in the low radiation region decreases, and it becomes necessary to increase the radiation exposure amount.

  Further, since the wiring intersecting with each gate wiring intersects with not only the signal wiring but also the reset wiring, the number of wirings intersecting with each gate wiring is increased, and the capacity of the gate wiring is increased. As a result, the time constant in the gate wiring becomes large and the driving speed cannot be increased.

  Therefore, in this embodiment, a configuration in which two TFTs are arranged so that high-speed driving for moving images can be performed will be described. In the case of a configuration in which two TFTs are arranged, a radiation detection device capable of capturing moving images that can be driven at low speed with high noise is provided by greatly reducing the capacitance between each gate wiring and signal wiring or reset wiring. It has a structure that can be done.

  FIG. 11 is a plan view of the present embodiment, and shows a pixel in which two TFTs as switch elements and a semiconductor conversion element are paired. A signal wiring 155 connected to the signal processing circuit portion is connected to the first TFT 170. A reset wiring for resetting the charge accumulated in the pixel is connected to the second TFT 171. In addition, the first gate wiring 172 connected to the first gate driver circuit 175 that controls the first TFT 170 is connected to the first gate electrode. The second gate wiring 173 connected to the second gate driver circuit 176 that controls the second TFT 171 is connected to the second gate electrode. The semiconductor conversion element is connected to both the first TFT 170 and the second TFT 171. By using the pixel having such a plan view, the operation of transferring the charge in the semiconductor conversion element to the signal processing circuit through the signal wiring 155 and the reset of the remaining charge accumulated in the pixel after the transfer of the charge are performed. It is possible to perform the operation to be performed simultaneously. For example, the remaining charge of the lower semiconductor conversion element that has been read can be reset through the reset wiring 174 while reading the charge accumulated in the semiconductor conversion element of the upper pixel in FIG. . As a result, reading and reset processing can be performed at the same time, and high-speed driving can be achieved.

  Thus, in the case of adopting the configuration of a pixel having two TFTs, the problem is to reduce the capacitance of each wiring which increases. For example, the number of signal wirings 155 crossing the gate wiring increases to double because the number of gate wirings has doubled. As a result, the capacity of the signal wiring 155 increases and the noise of the sensor increases.

  Further, even when viewed from the gate wiring, since not only the signal wiring 155 but also the reset wiring 174 crosses, the number crossing the wiring is doubled. As a result, the time constant in the gate wiring is increased as compared with the configuration of one TFT, and it is necessary to decrease the driving speed for driving the driver circuit.

  Therefore, as shown in FIG. 12, by providing a thick insulating layer at the intersection between the wirings, the capacitance at the intersection is reduced, and two capacitances can be obtained without increasing the capacitance of the signal wiring and each gate wiring. A pixel structure provided with TFTs can be achieved. Therefore, it is possible to achieve a radiation imaging apparatus that can be driven at high speed with low noise.

  FIG. 12 is a cross-sectional view taken along the line D-D ′ in FIG. 11. The right TFT in FIG. 12 represents the first TFT 170, and the left TFT represents the second TFT 171. As shown in the figure, the signal wiring made of the third metal layer 107 is disposed on the upper part of the TFT with a thick insulating layer interposed therebetween. The reset wiring has the same configuration. As a result, the distance between the gate wiring and the signal wiring can be increased, and the capacitance generated at the intersection of the wiring can be reduced to the limit. The thick insulating layer is preferably made of a material that can be formed thick and has a low dielectric constant. For example, as an inorganic material, a silicon oxide film or a silicon nitride film is preferably formed to have a thickness of about 1.0 μm to 4.0 μm. If an organic material is used, it may be formed with a thickness of about 3.0 μm to 10.0 μm, for example.

  FIG. 13 is a simplified equivalent circuit diagram of a radiation imaging apparatus including pixels in which two TFTs and one semiconductor conversion element of the present embodiment are paired. Around the substrate, a first gate driver circuit 175 for controlling the first TFT 170 for transferring charges and a second gate driver circuit 176 for controlling the second TFT 171 for resetting the pixels are arranged. Has been. Further, a signal processing circuit 150 connected to the signal wiring 155, a reset control circuit unit connected to the reset wiring, and a common electrode driver circuit unit 156 connected to the bias wiring 157 are arranged. Here, although it is simply a matrix of 5 rows × 4 columns, it actually consists of pixels such as 1000 rows × 1000 columns.

  With the structure described above, it is possible to realize a radiation imaging apparatus having a pixel in which two TFTs and one semiconductor conversion element are paired and can be driven at high speed with low noise.

(Fourth embodiment)
A fourth embodiment of the present invention will be described.

  The main point of this embodiment is that, from the first, second, and third embodiments, an insulating layer made of an organic material having a low relative dielectric constant is used as a suitable material constituting the insulating layer, and the film thickness is further defined. That's what it means.

  The organic material is preferably a material having high heat resistance such as polyimide resin or acrylic resin, and a relative dielectric constant of about 2.5 to 4 is preferable. The thickness of the insulating layer made of an organic material is desirably 1 μm or more even in a thin region.

  As the total thickness of the insulating layer made of an organic material increases, the capacity can be reduced. However, as the total thickness of the insulating layer increases, the thickness of the semiconductor conversion layer disposed on the insulating layer after forming the insulating layer and the wiring disposed in the region sandwiched between the insulating layers are formed by photolithography. Processing becomes difficult. For example, when the total thickness of the insulating layers exceeds 20 μm, when the photosensitive photoresist is coated, a region having poor resist adhesion occurs due to a large step. Further, the resist film thickness is increased only at the concave portion of the stepped portion, and the photoresist cannot be completely exposed in the subsequent exposure and development processes, resulting in a pattern residue. This is also the case inside the pixel. For example, at the boundary between the region where the insulating layer is not disposed and the region where the insulating layer is not disposed in the region outside the pixel region, the resist film thickness is increased only at the boundary portion and the pattern is formed along the boundary. The rest occurs. For example, when such a pattern residue occurs when patterning a metal film or a transparent electrode, a pattern short circuit between wirings is caused, so that it is difficult to stably manufacture by a photolithography process. Therefore, depending on the use of the insulating layer to be used, it is necessary to increase the thickness of necessary portions and to arrange unnecessary portions while controlling the thickness to be reduced. Moreover, it is necessary to make the total film thickness of an insulating layer into 20 micrometers or less.

  FIG. 14 shows a case where an insulating layer made of an organic material is used for the first insulating layer 106 and the second insulating layer 109 in this embodiment. As shown in FIG. 14, the second insulating layer 109 is formed thicker than the first insulating layer 106. For example, the first insulating layer 106 is formed with a thickness of 1 to 3 μm, and the second insulating layer 109 is formed with a thickness of about 2 to 10 μm. This is because the area of the lower electrode of the semiconductor conversion element made of the fourth metal layer 108 is large, so that a large capacitance is generated between the lower electrode and the signal wiring made of the third metal layer 107 arranged immediately below the lower electrode. This is to prevent formation. Therefore, by increasing the thickness of the second insulating layer 109 arranged between the signal wiring and the lower electrode, the capacitance formed between the two can be reduced. Further, the thickness of the first insulating layer 106 is reduced because the area where the signal wiring and the gate wiring (not shown) connected to the gate electrode made of the first metal layer overlap is shown in FIG. This is because it is extremely smaller than the area overlapping the lower electrode as shown in FIG.

  Originally, even if the area is small, the capacity can be surely reduced by increasing the film thickness. Therefore, the thicker the first insulating layer 106 is, the better. However, when the film thicknesses of both the first insulating layer 106 and the second insulating layer 109 are, for example, 10 μm, the pattern step is 20 μm between the region where the both insulating layers are disposed and the region where the both insulating layers are not disposed. Also become. As a result, when the semiconductor conversion element is formed using the photolithography method after the insulating layer is formed, a pattern residue is generated at the boundary portion where the insulating layer is patterned. For example, a conductive film such as a bias wiring made of a fifth metal layer and a semiconductor conversion element upper electrode made of a transparent electrode layer 113 remains, so that the wiring is short-circuited, and the radiation detection apparatus is stably manufactured. Can not do.

  Therefore, in the present embodiment, in order to reduce the step at the boundary between the region where the insulating layer is disposed and the region where the insulating layer is not disposed, the first insulation disposed between the gate wiring and the signal wiring with small capacitance formation. The film thickness of the layer 106 is reduced. Here, the first insulating layer 106 and the second insulating layer 109 are more preferably light shielding members such as a black resist that do not transmit visible light.

  FIG. 15 is a cross-sectional view of a boundary portion between a region where the first insulating layer and the second insulating layer are disposed in FIG. 14 and a region where the first insulating layer and the second insulating layer are not disposed.

  The plurality of insulating layers have different boundary positions at the end portions of the respective insulating layers, and the total film thickness changes stepwise. That is, the position of the boundary between the region where each insulating layer is arranged and the region where no insulating layer is arranged are different between the region where all the plurality of insulating layers are arranged and the region where none is arranged.

  As described above, the radiation imaging apparatus can be stably manufactured by reducing the thickness of the insulating layer in a region where the capacitance is small. However, in order to further stabilize the manufacturing process, it is necessary to pattern the first insulating layer 106 and the second insulating layer 109 shown in FIG. 14 at different positions to avoid having a step at one place. Therefore, as shown in FIG. 15, the manufacturing process can be further stabilized by shifting the patterning positions of the first insulating layer 106 and the second insulating layer 109 and changing the total film thickness stepwise. . It is desirable that the distance T between the end portions of the insulating layer shown in the figure is at least as large as the thickness of the second insulating layer 109. In FIG. 15, the second insulating layer 109 may be formed so as to cover the patterning end portion of the first insulating layer 106. At this time, when patterning is performed using a photolithography method, the distance between the end portions of the insulating layer is at least that of the first insulating layer 106 because it is easily affected by the film thickness of the first insulating layer 106. It is desirable that the distance is greater than the film thickness.

(Fifth embodiment)
First, a fifth embodiment of the present invention will be described.

  16 and 17 are a plan view and a cross-sectional view of a pixel of the radiation detection apparatus according to the fifth embodiment of the present invention.

  The main point of this embodiment is that there are three or more insulating layers, two or more regions between the insulating layers, and each wiring is formed of a different metal layer.

  FIG. 16 is a plan view of a pixel of a radiation detection apparatus according to the third embodiment of the present invention. It is a plane layout diagram showing a pixel portion of 2 rows × 2 columns in an effective pixel region in which pixels in which a conversion element that converts radiation into an electrical signal and a switch element are paired are arranged in a matrix on an insulating substrate.

  The difference from FIG. 4 is that the first signal wiring 129 and the second signal wiring 130 are formed of different metal layers, and both are sandwiched by an insulating layer between the TFT portion and the semiconductor conversion element portion. It is the point formed with the metal layer.

  FIG. 17 is a cross-sectional view taken along the line EE ′ of FIG. 16, and the signal wiring is an example in which the same metal layer as the source electrode and the drain electrode of the TFT is formed.

  A description of portions common to FIG. 5 is omitted.

  The upper part shows a semiconductor conversion element, and the lower part shows a TFT. The upper semiconductor conversion element includes a fifth metal layer 114, an insulating layer 110 of the semiconductor conversion element, a second high-resistance semiconductor layer 111, a second impurity semiconductor layer 112 that is an ohmic contact layer, and a transparent electrode layer 113. This is a MIS type semiconductor conversion element. It is possible to photoelectrically convert light such as visible light. The sixth metal layer 118 is a bias wiring for applying a voltage to the transparent electrode layer, and is connected to a common electrode driver arranged outside the substrate.

  The first signal wiring 129 shown in FIG. 16 is formed of the third metal layer 107 of FIG. 17 and is arranged in a region sandwiched between the first insulating layer 106 and the second insulating layer 109. Has been. Further, the second signal wiring 130 shown in FIG. 16 is formed of the fourth metal layer 108 of FIG. 17, and is a region sandwiched between the second insulating layer 109 and the third insulating layer 115. Is arranged.

  Here, the first insulating layer 106, the second insulating layer 109, and the third insulating layer 115 are made of an organic material. The organic material is preferably a material having high heat resistance such as polyimide resin or acrylic resin, and a relative dielectric constant of about 2.5 to 4 is preferable. The thickness of the insulating layer made of an organic material is desirably 1 μm or more.

  As a result, as shown in FIG. 4, even if the signal wiring is divided into two systems and the number of signals wiring is doubled as usual, the capacity formed by the semiconductor conversion element and the signal wiring arranged on the upper part increases. Can be prevented. In addition, the degree of freedom of wiring routing is increased. For example, the capacitance formed between the first signal wiring 129 and the second signal wiring 130 can be reduced by changing the arrangement location. It is possible to provide a low-noise radiation imaging apparatus that is compatible with high-speed moving images. Furthermore, when the wiring width is increased to reduce the resistance of the wiring, or in the case of a radiation detection apparatus that can capture a high-definition image with a pixel pitch of, for example, 50 to 160 μm, the two signal wirings are made of different metal layers. When formed, the effect of reducing the capacity is great.

  That is, when the number of wirings increases, a plurality of protective films can be arranged, and the wirings can be selectively arranged in the protective film, and the wiring capacity can be reduced. In addition, after the first insulating layer 106 and the second insulating layer 109 made of an organic material are disposed, the high temperature process of, for example, 300 ° C. or higher may not be performed. In this case, the gate wiring is disposed in a region sandwiched between the first insulating layer 106 and the second insulating layer 109, and the signal wiring is disposed in a region sandwiched between the second insulating layer 109 and the third insulating layer 115. May be. In this case, aluminum having a small specific resistance may be used for the gate wiring.

(Sixth embodiment)
First, a sixth embodiment of the present invention will be described.

  18 to 22 are a simplified equivalent circuit diagram of a radiation imaging apparatus, and a plan view and a sectional view of a pixel of the radiation detection apparatus according to a sixth embodiment of the present invention.

  The main point of this embodiment is that a plurality of signal wirings are provided for a plurality of pixels in one column, a plurality of continuous pixels in one column are allocated to each signal wiring, and the thin film transistor of the pixel to which each signal wiring is allocated Is connected to.

  FIG. 18 is a simplified equivalent circuit diagram of a radiation imaging apparatus according to the fourth embodiment of the present invention.

  The pixel area is divided into two areas, and a first signal wiring for reading image data from the upper 3 rows × 6 columns area and a second signal line for reading image data from the lower 3 rows × 6 columns area The signal wiring is arranged separately. In addition, the signal processing circuit unit and the gate driver circuit unit arranged on the same side are controlled.

  In the substrate 160, pixels that form pairs of TFT portions 152 and semiconductor conversion element portions 153 that are switching elements are arranged in a matrix. A gate wiring 154, a first signal wiring 129, and a second signal wiring 130 are connected to the TFT portion, and a bias wiring 157 from the common electrode driver circuit portion 156 is connected to the semiconductor conversion element portion 153. .

  The difference from FIG. 3 shown in the first embodiment is that the signal wiring is divided into two parts, a first signal wiring 129 and a second signal wiring. The first signal wiring 129 is connected to the TFT unit 152 connected to the semiconductor conversion element unit 153 of 3 rows × 6 columns arranged in the upper part, and the second signal wiring 130 is connected to the three rows arranged in the lower part. It is connected to the TFT portion 152 connected to the semiconductor conversion element portion 153 of × 6 rows. The second signal wiring 130 is connected to another metal layer through a through-hole 161 disposed at the center of the substrate, and is routed to the signal processing circuit unit 150 disposed outside the substrate.

  As a result, a signal from the semiconductor conversion element arranged in a region far from the signal processing circuit unit can be transmitted to the signal processing circuit unit arranged on one side of a certain substrate. At the same time, by dividing the signal wiring into a plurality of areas, for example, the number of TFTs connected to one signal wiring and the number of intersections with the gate wiring can be reduced, and the total capacity of the signal wiring can be reduced. it can. Further, by simultaneously driving the gate wirings arranged in the upper and lower areas, a plurality of signals can be read simultaneously, and high-speed driving can be performed.

  FIG. 19 is a conceptual diagram showing a relationship between a pixel region in a substrate and a peripheral circuit of a radiation imaging apparatus according to the fourth embodiment of the present invention.

  The connection state of the area | region where the semiconductor conversion element is arrange | positioned in a board | substrate, and the signal processing circuit part and gate driver circuit part arrange | positioned in the periphery is represented. 18 is an arrangement example in which the radiation detection apparatus in which the semiconductor conversion element as shown in FIG. 18 is divided into a plurality of areas and a dedicated signal wiring is arranged in each area is shown in another configuration.

  In FIG. 19, the semiconductor conversion element arranged in the substrate is divided into four areas 1 to 4, and dedicated signal wirings are arranged in each of them. Outside the substrate, a first signal processing circuit unit 162 that can capture signals from the upper two areas, a second signal processing circuit unit 163 that can capture signals from the two lower areas, Is arranged. Further, a first gate driver circuit unit 164 and a second gate driver circuit unit 165 for controlling the gate electrodes arranged in the respective areas are arranged. Although not shown in the drawing, the common electrode driver circuit unit or power source for applying a voltage to the semiconductor conversion element is arranged in the signal processing circuit unit or the gate driver circuit unit.

  In this manner, the number of TFTs connected to one signal wiring can be reduced to ¼ by dividing the pixel region into four. As a result, the capacitance formed between the source electrode and the gate electrode of the TFT portion is reduced, and the total capacitance of the signal wiring can be reduced. At this time, for example, the wiring routed from the section 2 to the first signal processing circuit unit 162 is sandwiched between organic materials that are insulating layers at least in a portion passing through the section 1, for example, a semiconductor conversion element is formed on the upper portion thereof. Even if it is arranged, the capacity formed can be reduced. For this reason, the total capacity of the signal wiring can be kept small while ensuring a large aperture ratio of the semiconductor conversion element. It is also possible to perform high-speed driving by simultaneously driving four gate wirings selected from each area and simultaneously sending them to the signal processing circuit.

  With respect to the gate wiring, the first gate driver circuit portion 164 and the second gate driver circuit portion 165 may be connected to each other by a gate wiring arranged in the substrate, and the gate wiring is separated into the right and left at the center. It does not matter.

  FIG. 20 is a simplified equivalent circuit diagram of a radiation imaging apparatus according to the sixth embodiment of the present invention, and shows a different example from FIG.

  The difference is that the first signal wiring 129 extends to the lower 3 rows × 6 columns area where it is not connected to the TFT. This is to make the time constant and total capacity of the first signal wiring 129 and the second signal wiring 130 the same as much as possible. By adopting a structure in which the upper and lower sides are sandwiched between organic materials, capacitance formation with the surroundings can be kept small, but it cannot be completely eliminated. For this reason, if the length of the wiring is different or the number of crossings is different, the total capacity of the wiring changes. This difference in total capacity changes the time constant in the wiring or changes the wiring noise, and the image information from the semiconductor conversion element has different properties for each section.

  Here, the first signal wiring 129 for reading a signal from the upper area is preferably sandwiched by an organic material that is less susceptible to the influence of the periphery from the center through hole 161 and has a small capacitance formation. In addition, the second signal wiring 130 for reading a signal from the lower area is less susceptible to the influence of the periphery above the through hole 161 in the central portion, has a small capacitance formation, and is below the first signal wiring 129. The structure is the same as that used in the area, sandwiched between organic materials. That is, the metal layers of the first signal wiring 129 and the second signal wiring 130 are switched with the through hole 161 as a boundary.

  As a result, the total capacity of the first signal wiring 129 and the second signal wiring 130 becomes the same, for example, the time constant and wiring noise in the wiring can be made equal for each area, and radiation is imaged. , You don't have to feel uncomfortable with images with different properties in each area.

  FIG. 21 is a plan view of a pixel of the radiation detection apparatus according to the fourth exemplary embodiment of the present invention.

  FIG. 3 is a plan layout diagram showing a pixel portion of 2 rows × 2 columns in an effective pixel region in which pixels that are paired with semiconductor conversion elements and TFTs that convert radiation into electrical signals are arranged in a matrix.

  The source electrodes 123 of the four TFTs arranged in the area of 2 rows × 2 columns are all connected to the first signal wiring 129, and the second signal wiring 130 is the pixel of the pixel arranged in another area. It is connected to the source electrode of the TFT. Here, the first signal wiring 129 is formed simultaneously with the source electrode 123, and the second signal wiring 130 not connected to the TFT in the area shown in FIG. 21 is the first signal wiring 129. It is formed using different metal layers arranged on top.

  FIG. 22 is a cross-sectional view taken along the line FF ′ of FIG. 21, and the signal wiring is an example in the case where the same metal layer as the source electrode and the drain electrode of the TFT is formed.

  A description of portions common to FIG. 5 is omitted.

  The upper part shows a semiconductor conversion element, and the lower part shows a TFT. The upper semiconductor conversion element includes a fourth metal layer 108, an insulating layer 110 of the semiconductor conversion element, a second high-resistance semiconductor layer 111, a second impurity semiconductor layer 112 that is an ohmic contact layer, and a transparent electrode layer 113. This is a MIS type semiconductor conversion element. It is possible to photoelectrically convert light such as visible light. The fifth metal layer 114 is a bias wiring for applying a voltage to the transparent electrode layer, and is connected to a common electrode driver circuit unit arranged outside the substrate.

  The first signal wiring 129 shown in FIG. 21 is formed of the second metal layer 105 of FIG. 22 and is arranged in a region sandwiched between the gate insulating layer 102 and the first insulating layer 106. Yes. The second signal wiring 130 is formed of the third metal layer 107 in FIG. 17 and is disposed in a region sandwiched between the first insulating layer 106 and the second insulating layer 109. As shown in the simplified equivalent circuit of FIG. 20, the first signal wiring 129 and the second signal wiring 130 are arranged to extend in order to have the same capacitance. In this case, the second signal wiring 130 is formed of the second metal layer 105 connected to the source electrode of the pixel TFT in a region different from FIG. In the region of FIG. 21, the first signal wiring 129 is not connected to the TFT and is formed of the third metal layer 107.

(Seventh embodiment)
In the seventh embodiment, a radiation detection apparatus for moving images is provided in which two transistors are arranged in one pixel so that high-speed driving is possible. The main point of this embodiment is that a pixel in which one semiconductor conversion element and two TFTs are paired is two-dimensionally arranged. For example, one TFT is used for charge transfer and the other TFT is used for resetting. This is the point. According to this embodiment, an image can be captured and reset at high speed. For the TFT, it is preferable to use polysilicon capable of high-speed transfer because charge transfer and charge reset can be performed immediately. At this time, when the gate wiring of the TFT uses a refractory metal such as chromium, titanium, or tantalum, the wiring resistance is high. Therefore, if the wiring width is increased, the wiring capacity increases. Therefore, by disposing the gate wiring on the TFT with the insulating layer interposed therebetween, a material having a small specific resistance such as aluminum or copper can be used. At this time, signal wiring or reset wiring connected to the source or drain electrode of the TFT portion is also arranged on the gate wiring with the insulating layer interposed therebetween. Further, a semiconductor conversion element is disposed above these wirings with an insulating layer interposed therebetween. That is, the gate electrode, source electrode, and drain electrode of the TFT portion are formed. Thereafter, an insulating layer is formed. After that, one of the gate wiring and the signal wiring is formed, and after the insulating layer is further formed, the other of the gate wiring and the signal wiring is formed. By forming the semiconductor conversion element after forming the insulating layer again, the wiring resistance and the wiring capacitance can be reduced. Accordingly, it is possible to provide a radiation imaging apparatus that can be driven at high speed with low noise. Here, it is desirable that the three insulating layers have a low dielectric constant and a large film thickness. For example, when an organic insulating film is used, it is possible to reduce the capacitance between the TFT portion, the gate wiring, the signal wiring and the reset wiring, and the semiconductor conversion element, and a radiation imaging apparatus that can be driven at high speed with low noise. Can be provided.

(Eighth embodiment)
Next, an eighth embodiment of the present invention will be described.

  25 and 26 are a plan view and a cross-sectional view of a pixel of the radiation detection apparatus according to the eighth embodiment of the present invention.

  The main point of this embodiment is that there are three or more insulating layers, two or more regions sandwiched between the insulating layers, and each wiring is formed of a different metal layer.

  FIG. 25 is a plan view of a pixel of the radiation detection apparatus according to the eighth embodiment of the present invention.

  It is a plane layout diagram showing a pixel portion of 2 rows × 2 columns in an effective pixel region in which pixels in which a conversion element that converts radiation into an electrical signal and a switch element are paired are arranged in a matrix on an insulating substrate.

  The difference from FIG. 1 is that the gate electrode 136 and the gate wiring 122 are formed of different metal layers, and are connected to each other by a through hole 138 for each pixel.

  26 is a cross-sectional view taken along line GG ′ in FIG. The upper part shows a semiconductor conversion element, and the lower part shows a TFT. The signal wiring is an example in the case of using the same metal layer as the source electrode and drain electrode of the TFT.

  The upper semiconductor conversion element includes a fifth metal layer 114, an insulating layer 110 of the semiconductor conversion element, a second high-resistance semiconductor layer 111, a second impurity semiconductor layer 112 that is an ohmic contact layer, and a transparent electrode layer 113. This is a MIS type semiconductor conversion element. It is possible to photoelectrically convert light such as visible light. The sixth metal layer 118 is a bias wiring for applying a voltage to the transparent electrode layer, and is connected to a common electrode driver arranged outside the substrate.

  The signal wiring 121 shown in FIG. 25 is formed of the fourth metal layer 108 of FIG. 26 and is arranged in a region sandwiched between the second insulating layer 109 and the third insulating layer 115. . 25 is formed of the first metal layer 101 of FIG. 26, and the gate wiring 122 is formed of the third metal layer 107 (in the second insulating layer 109 in the figure). Dotted line shown in Further, the gate electrode 136 and the gate wiring 122 are connected by a through hole (a dotted line portion shown in the first insulating layer 106 in the drawing). Here, the first insulating layer 106, the second insulating layer 109, and the third insulating layer 115 are made of an organic material. The organic material is preferably a material having high heat resistance such as polyimide resin or acrylic resin, and a relative dielectric constant of about 2.5 to 4 is preferable. In such a configuration, for example, the gate insulating layer 102 that is an insulating film of the TFT portion is formed of a high-temperature inorganic film formed at 300 to 350 ° C., for example, while forming a highly reliable TFT. In the case where the specific resistance is low aluminum wiring is preferable.

  Here, the thickness and relative dielectric constant of the first insulating layer 106 are T1, ε1, the thickness of the second insulating layer 109 is T2, ε2, and the thickness of the third insulating layer 115 is T3, ε3. . As can be seen from FIG. 25, the areas where the conductive metal films intersect each other are the largest in the gate wiring 122 and the lower electrode 126 (area S1), and then the signal wiring 121 and the lower electrode 126 (area S2). The signal wiring 121 and the gate wiring 122 (area S3) are arranged in this order. That is, when the relationship S1> S2> S3 is established, the capacitances C1, C2, and C3 per unit area formed at each intersection are designed so that the relationship C1 <C2 <C3 is established.

  Thus, the capacity formed by the metal layers can be kept small while designing the thickness and relative dielectric constant of the insulating layer and making the insulating layer as thin as possible.

  The first to eighth embodiments of the present invention have been described above. Hereinafter, a mounting example of a radiation imaging apparatus using the radiation detection apparatus of the present invention and an application example of the radiation imaging apparatus to a radiation imaging system will be described. .

  FIG. 23 is a schematic configuration diagram of a mounting example of a radiation imaging apparatus (X-ray imaging apparatus) using the radiation detection apparatus of the present invention, where (a) is a plan view and (b) is a cross-sectional view.

  A plurality of semiconductor conversion elements and TFTs which are photoelectric conversion elements are formed in a sensor substrate 6011, and a flexible circuit board 6010 on which a shift register SR1 and a detection integrated circuit IC are mounted is connected. The opposite side of the flexible circuit board 6010 is connected to the circuit boards PCB1 and PCB2. A plurality of sensor substrates 6011 are bonded on a base 6012 to constitute a large photoelectric conversion device. A lead plate 6013 is mounted under the base 6012 in order to protect the memory 6014 and the circuit element 6019 in the processing circuit 6018 from X-rays. On the sensor substrate 6011, a scintillator (phosphor layer) 6030 for converting X-rays into visible light, for example, CsI is deposited. As shown in FIG. 23B, the whole is housed in a case 6020 made of carbon fiber.

  FIG. 24 is a diagram showing an application example of a radiation imaging apparatus using the radiation detection apparatus of the present invention to a radiation imaging 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 layer) 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 is digitally converted and image-processed by an image processor 6070 serving as signal processing means, and can be observed on a display 6080 serving as 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 display means such as a doctor room in another place or stored in recording means such as an optical disk. As a result, it is possible for a remote 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.

  The present invention can be applied to radiation detection apparatuses such as X-rays for medical use and non-destructive inspection. Further, the present invention can be applied to a radiation detection apparatus that converts light such as visible light into an electric signal, particularly a radiation detection apparatus having a large-area photoelectric conversion region.

101 first metal layer 102 gate insulating layer 105 second metal layer 106 first insulating layer 107 third metal layer 108 fourth metal layer 109 second insulating layer 114 fifth metal layer 115 third Insulating layer 116 Phosphor layer 117 Protective layer 118 Sixth metal layer 121 Signal wiring 122 Gate wiring 127 Bias wiring 129 First signal wiring 130 Second signal wiring 135 Third signal wiring 140 First gate wiring 141 First gate wiring 141 Second gate wiring 142 Third gate wiring 161 Through hole

Claims (11)

A switch element comprising: a gate electrode disposed on an insulating substrate; and a source electrode and a drain electrode disposed on a gate insulating layer covering the gate electrode;
A conversion element for converting radiation disposed on the switch element into an electric charge connected to one of a source electrode and a drain electrode of the switch element;
A gate wiring connected to the gate electrode of the switch element;
A signal line connected to the other of the source electrode and the drain electrode of the switch element and arranged to intersect the gate line;
A radiation detection apparatus comprising:
A plurality of insulating layers are disposed between the switch element and the conversion element,
At least one of the gate wiring and the signal wiring is made of a metal layer having a lower melting point and a lower specific resistance than the gate electrode, which is disposed between the plurality of insulating layers. . The plurality of insulating layers comprises three or more layers,
The gate wiring is disposed between two insulating layers of the plurality of insulating layers,
The signal wiring is disposed between one of the two insulating layers of the plurality of insulating layers and two insulating layers including different insulating layers,
The radiation detection apparatus according to claim 1, wherein the gate wiring and the signal wiring are made of a metal layer having a lower melting point and a lower specific resistance than the gate electrode. A plurality of pixels each including the conversion element and the switch element are two-dimensionally arranged in a matrix on the insulating substrate,
A plurality of the gate wirings commonly connected to the gate electrodes of the plurality of switch elements in the row direction are arranged in the column direction,
3. The radiation detection according to claim 1, wherein a plurality of the signal wirings connected in common to the other of the source electrode and the drain electrode of the plurality of switch elements in the column direction are arranged in the row direction. apparatus.   The radiation detection apparatus according to claim 1, wherein film thicknesses of the plurality of insulating layers are different from each other.   The radiation detection according to any one of claims 1 to 4, wherein the plurality of insulating layers have different boundary positions at end portions of the respective insulating layers, and the total film thickness changes stepwise. apparatus. Another insulating layer different from the at least one insulating layer of the plurality of insulating layers is disposed between at least one of the gate wiring and the signal wiring and the electrode of the conversion element,
The film thickness of the at least one insulating layer is determined in consideration of the area where the gate wiring and the signal wiring intersect with each other and the relative dielectric constant of the material of the at least one insulating layer,
The film thickness of the another insulating layer takes into consideration the area where at least one of the gate wiring and the signal wiring intersects the electrode of the conversion element, and the relative dielectric constant of the material of the other insulating layer. The radiation detection apparatus according to claim 1, wherein the radiation detection apparatus is determined. A gate electrode disposed on an insulating substrate and covered with the first insulating layer; and a source electrode and a drain electrode disposed on the first insulating layer, the source electrode and the drain electrode One of the reset switch element connected to the conversion element,
A second gate wiring composed of the metal layer connected to the gate electrode of the reset switch element;
A reset wiring connected to the other of the source electrode and the drain electrode of the reset switch element;
Further comprising
At least one of the second gate wiring and the reset wiring is disposed between the plurality of insulating layers, and the at least one insulating layer and the first insulating layer are the second gate wiring and the reset wiring. The radiation detection apparatus according to claim 1, wherein the radiation detection apparatus is disposed between the two. A plurality of pixels each including the conversion element, the switch element, and the reset switch element are two-dimensionally arranged in a matrix on the insulating substrate,
A plurality of the gate wirings commonly connected to the gate electrodes of the plurality of switch elements in the row direction are arranged in the column direction,
A plurality of the signal wirings connected in common to the other of the source electrode and the drain electrode of the plurality of switch elements in the column direction are arranged in the row direction,
A plurality of the second gate wirings connected in common to the gate electrodes of the plurality of reset switching elements in the row direction are arranged in the column direction;
The radiation detection according to claim 7, wherein a plurality of the reset wirings connected in common to the other of the source electrode and the drain electrode of the plurality of reset switching elements in the column direction are arranged in the row direction. apparatus.   9. The radiation detection apparatus according to claim 1, further comprising a wavelength conversion layer that converts radiation into light in a wavelength region capable of photoelectric conversion, wherein the conversion element converts light into an electrical signal. A radiation detection apparatus characterized by being an element for conversion.   9. The radiation detection apparatus according to claim 1, wherein the conversion element is an element that directly converts radiation into an electrical signal. The radiation detection apparatus according to claim 9 or 10,
Signal processing means for processing signals from the radiation detection device;
Display means for displaying a signal from the signal processing means;
Transmission processing means for transmitting a signal from the signal processing means;
A radiation imaging system comprising:

Images