JP2009162586A - Radiation detector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce the separation between an electric wire and an electrode part while maintaining radiation detection sensitivity. <P>SOLUTION: A first filler 444 to be filled on a detectable area is made of an element with the atomic number of nine or less, providing better radiation transmittance as compared to a case in which it is made of an element with the atomic number exceeding nine. This allows the radiation detection sensitivity to be maintained in the detectable area. A connecting part in which a bias electrode 401 and the electric wire are connected to each other is filled with an elastic second filler 445, maintaining the adhesion between an extended electrode part 431 and a high-voltage line 432 and reducing the separation between the high-voltage line 432 and the extended electrode part 431 as compared to a filler having curability. Different fillers are thus used for the connecting part in which the extended electrode part 431 and the high-voltage line 432 are connected to each other and the detectable area, maintaining the radiation detection sensitivity and reducing the separation between the high-voltage line 432 and the electrode part. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a radiation detector used in a medical X-ray imaging apparatus or the like.

  As the radiation detector, a flat detector disclosed in Patent Document 1 and an X-ray flat detector disclosed in Patent Document 2 are known.

  In the flat detector disclosed in Patent Document 1, an upper electrode part is formed on a charge conversion layer formed of amorphous selenium or the like, and an electric wire is connected to the upper electrode part outside a radiation detection region for detecting radiation. Yes.

  Further, in the X-ray flat panel detector disclosed in Patent Document 2, the upper electrode portion formed on the charge conversion layer is pulled down to the glass substrate along the side surface of the charge conversion layer, and the conductive property such as an ITO film is obtained. A configuration is disclosed in which a high-voltage line drawn from outside and an upper electrode portion are connected by a connection pad formed on a glass substrate using a material.

As described above, as an insulation method of the connection portion between the upper electrode portion and the electric wire connected to the upper electrode portion, after the electric wire is connected and fixed to the upper electrode portion, the connection portion between the electric wire and the upper electrode portion is made of epoxy. A method is known in which a curable resin is filled and insulated.
Japanese Patent Laid-Open No. 11-211837 JP 2000-241556 A

  However, since it hardens | cures in the curable resin comprised with the epoxy, there exists a possibility that the adhesiveness of a filler may be bad to an electric wire and an electrode part, and an electric wire and an electrode part may peel.

  In view of the above facts, an object of the present invention is to provide a radiation detector capable of suppressing the separation between the electric wire and the electrode part while maintaining the radiation detection sensitivity.

  A radiation detector according to claim 1 of the present invention includes a charge conversion layer that generates charges when radiation is incident thereon, and a lower part that is provided under the charge conversion layer and collects charges generated by the charge conversion layer. An electrode part; a substrate on which the lower electrode part is provided; an upper electrode part formed on the charge conversion layer for applying a bias voltage to the charge conversion layer; and the lower electrode part collecting charges. And an extended electrode portion extended from the upper electrode portion outside the detectable region where radiation can be detected, and connected to the extended electrode portion outside the detectable region, and the upper electrode portion is connected from the extended electrode portion. An electric wire for applying a bias voltage to the charge conversion layer via the first filling material filled in the detectable region and composed of an element having an atomic number of 9 or less, the extension electrode portion, and the electric wire, Is connected Filled in that the connecting portion, characterized by comprising a second filler having elasticity, a.

  According to this configuration, a bias voltage is applied from the extension electrode portion to the charge conversion layer via the upper electrode portion by the electric wire connected to the extension electrode portion. The charge conversion layer generates charges when radiation is incident thereon. The charges generated by the charge conversion layer are collected by the lower electrode part.

  Here, in the structure of Claim 1, since the 1st filler with which a detection area | region is filled is comprised with the element of atomic number 9 or less, it is compared with the case where it comprises with an element exceeding atomic number 9. Therefore, the radiation permeability is good. For this reason, the radiation detection sensitivity can be maintained in the detectable region.

  In addition, since the connection portion where the upper electrode portion and the electric wire are connected is filled with the second filler having elasticity, the adhesion between the extension electrode portion and the electric wire as compared with the curable filler. However, peeling between the electric wire and the electrode portion can be suppressed.

  As described above, in the present invention, by separating the filler between the connecting portion where the extension electrode portion and the electric wire are connected and the detectable region, the separation between the electric wire and the electrode portion is achieved while maintaining the detection sensitivity of radiation. Suppress.

  Since this invention set it as the said structure, peeling of an electric wire and an electrode part can be suppressed, maintaining the detection sensitivity of a radiation.

  Below, an example of an embodiment of a radiation detector concerning the present invention is explained based on a drawing.

  The radiation detector according to the present embodiment is used in an X-ray imaging apparatus or the like, and includes an electrostatic recording unit including a photoconductive layer that exhibits conductivity when irradiated with radiation. The image information is recorded upon receiving the irradiation of the radiation carrying the image, and the image signal representing the recorded image information is output.

  As the radiation detector, a so-called optical reading type radiation detection substrate 500 that reads using a semiconductor material that generates charges by light irradiation, and charges generated by radiation irradiation are accumulated, and the accumulated charges are stored in a thin film transistor. There is a radiation detector 400 or the like of a method of reading by turning on and off an electrical switch such as a TFT (thin film transistor) one pixel at a time (hereinafter referred to as TFT method).

(Configuration of TFT radiation detector 400)
First, the configuration of the TFT radiation detector 400 will be described. FIG. 1 is a schematic cross-sectional view showing the overall configuration of a TFT radiation detector 400. FIG. 2 shows the configuration of the main part of a TFT radiation detector 400, and shows each part laminated on a glass substrate.

  As shown in FIGS. 1 and 2, the TFT radiation detector 400 according to the present embodiment has an electromagnetic wave conductivity as a charge conversion layer that generates charges when X-rays as an example of radiation are incident. The photoconductive layer 404 shown is provided. As the photoconductive layer 404, an amorphous material having a high dark resistance, good electromagnetic wave conductivity with respect to X-ray irradiation, and capable of forming a large area film at a low temperature by a vacuum deposition method is preferred.

  For example, an amorphous Se (a-Se) film is used as the amorphous material. A material obtained by doping As, Sb, and Ge into amorphous Se is excellent in thermal stability and is a suitable material for the photoconductive layer 404.

  On the photoconductive layer 404, a bias electrode 401 is formed as an example of an upper electrode portion for applying a bias voltage to the photoconductive layer 404. An electrode layer 430 is composed of the bias electrode 401 and an extended electrode portion 431 described later. For example, gold (Au) is used for the electrode layer 430.

  A plurality of charge collection electrodes 407a are formed under the photoconductive layer 404 as an example of the lower electrode portion. As shown in FIG. 2, the charge collection electrode 407a is connected to the charge storage capacitor 407c and the switch element 407b, respectively. The charge collection electrode 407a is provided on the glass substrate 408.

As shown in FIGS. 1 and 2, a hole injection blocking layer 402 is provided as an intermediate layer between the photoconductive layer 404 and the bias electrode 401. Here, the intermediate layer is a layer existing between the bias electrode 401 and the photoconductive layer 404, and may also serve as a charge injection blocking layer (including charge accumulation and diode formation). Although a resistance layer or an insulating layer may be used as the charge injection blocking layer, it is preferably a hole injection blocking layer that blocks hole injection while being a conductor for electrons, or for holes. For example, an electron injection blocking layer that blocks the injection of electrons while being a conductor is used. As the hole injection blocking layer, CeO ₂ , ZnS, Sb ₂ S ₃ can be used. Of these, ZnS is desirable because it can be formed at a low temperature. Examples of the electron injection blocking layer include Sb ₂ S ₃ , CdS, Te doped Se, CdTe, organic compounds, and the like. Note that Sb ₂ S ₃ becomes both a hole injection blocking layer and an electron injection blocking layer depending on the thickness provided. In this embodiment, since the bias electrode is a positive electrode, a hole injection blocking layer 402 is provided as an intermediate layer. Further, as shown in FIG. 2, an electron injection blocking layer 406 is provided between the photoconductive layer 404 and the charge collection electrode 407a.

Further, between the hole injection blocking layer 402 and the photoconductive layer 404 and between the electron injection blocking layer 406 and the photoconductive layer 404, as shown in FIG. Is provided. The crystallization preventing layer 403, 405 GeSe, can be used and _{GeSe 2, Sb 2 Se 3,} a-As 2 Se 3, Se-As, Se-Ge, a Se-Sb-based compounds.

  Note that an active matrix layer 407 is configured by the charge collection electrode 407a, the switch element 407b, and the charge storage capacitor 407c, and an active matrix substrate 450 is configured by the glass substrate 408 and the active matrix layer 407.

  3 is a cross-sectional view showing the structure of one pixel unit of the radiation detector 400, and FIG. 4 is a plan view thereof. The size of one pixel shown in FIGS. 3 and 4 is about 0.1 mm × 0.1 mm to 0.3 mm × 0.3 mm, and this pixel is arranged in a matrix of about 500 × 500 to 3000 × 3000 pixels in the radiation detector as a whole. Has been.

  As shown in FIG. 3, the active matrix substrate 450 includes a glass substrate 408, a gate electrode 411, a charge storage capacitor electrode (hereinafter referred to as Cs electrode) 418, a gate insulating film 413, a drain electrode 412, a channel layer 415, a contact electrode. 416, a source electrode 410, an insulating protective film 417, an interlayer insulating film 420, and a charge collection electrode 407a.

  The gate electrode 411, the gate insulating film 413, the source electrode 410, the drain electrode 412, the channel layer 415, the contact electrode 416, and the like constitute a switch element 407b made of a thin film transistor (TFT), and a Cs electrode 418. Further, a charge storage capacitor 407c is configured by the gate insulating film 413, the drain electrode 412 and the like.

  The glass substrate 408 is a support substrate. As the glass substrate 408, for example, an alkali-free glass substrate (for example, # 1737 manufactured by Corning) can be used. As shown in FIG. 4, the gate electrode 411 and the source electrode 410 are electrode wirings arranged in a lattice pattern, and a switch element 407b made of a thin film transistor is formed at the intersection.

  The source / drain of the switch element 407b is connected to the source electrode 410 and the drain electrode 412 respectively. The source electrode 410 includes a linear portion as a signal line and an extended portion for constituting the switch element 407b, and the drain electrode 412 is provided so as to connect the switch element 407b and the charge storage capacitor 407c. Yes.

  The gate insulating film 413 is made of SiNx, SiOx, or the like. The gate insulating film 413 is provided so as to cover the gate electrode 411 and the Cs electrode 418, and a part located on the gate electrode 411 acts as a gate insulating film in the switch element 407b, and a part located on the Cs electrode 418. Acts as a dielectric layer in the charge storage capacitor 407c. That is, the charge storage capacitor 407c is formed by an overlapping region of the Cs electrode 418 and the drain electrode 412 formed in the same layer as the gate electrode 411. The gate insulating film 413 is not limited to SiNx or SiOx, and an anodic oxide film obtained by anodizing the gate electrode 411 and the Cs electrode 418 can be used in combination.

  A channel layer (i layer) 415 is a channel portion of the switch element 407 b and is a current path connecting the source electrode 410 and the drain electrode 412. A contact electrode (n + layer) 416 makes contact between the source electrode 410 and the drain electrode 412.

  The insulating protective film 417 is formed over almost the entire surface (substantially the entire region) on the source electrode 410 and the drain electrode 412, that is, on the glass substrate 408. Thus, the drain electrode 412 and the source electrode 410 are protected, and electrical insulation and separation are achieved. Further, the insulating protective film 417 has a contact hole 421 at a predetermined position thereof, that is, at a portion located on a portion of the drain electrode 412 facing the Cs electrode 418.

  The charge collection electrode 407a is made of an amorphous transparent conductive oxide film. The charge collection electrode 407a is formed so as to fill the contact hole 421, and is stacked on the source electrode 410 and the drain electrode 412. The charge collection electrode 407a and the photoconductive layer 404 are electrically connected to each other so that charges generated in the photoconductive layer 404 can be collected by the charge collection electrode 407a.

  Next, the charge collection electrode 407a will be described in detail. The charge collection electrode 407a used in this embodiment is composed of an amorphous transparent conductive oxide film. Examples of amorphous transparent conductive oxide film materials include oxides of indium and tin (ITO: Indium-Tin-Oxide), oxides of indium and zinc (IZO: Indium-Zinc-Oxide), indium and germanium. An oxide (IGO: Indium-Germanium-Oxide) or the like having a basic composition can be used.

  As the charge collection electrode 407a, various metal films and conductive oxide films are used, and transparent conductive oxide films such as ITO (Indium-Tin-Oxide) are often used for the following reasons. When the incident X-ray dose is large in the radiation detector 400, unnecessary charges may be trapped in the semiconductor film (or in the vicinity of the interface between the semiconductor film and an adjacent layer).

  Such residual charges are stored in memory for a long time or move while taking time, so that X-ray detection characteristics deteriorate during subsequent image detection, and afterimages (virtual images) appear. Therefore, in Japanese Patent Laid-Open No. 9-9153 (corresponding US Pat. No. 5,563,421), when residual charges are generated in the photoconductive layer 404, the residual charges are reduced by irradiating light from the outside of the photoconductive layer 404. A method of removing by excitation is disclosed. In this case, in order to irradiate light efficiently from the lower side of the photoconductive layer 404 (on the side of the charge collection electrode 407a), the charge collection electrode 407a needs to be transparent to the irradiation light.

  In addition, for the purpose of increasing the area filling factor (fill factor) of the charge collection electrode 407a or for shielding the switch element 407b, it is desirable to form the charge collection electrode 407a so as to cover the switch element 407b. If the collection electrode 407a is opaque, the switch element 407b cannot be observed after the charge collection electrode 407a is formed.

  For example, when the characteristic inspection of the switch element 407b is performed after the charge collection electrode 407a is formed, if the switch element 407b is covered with the opaque charge collection electrode 407a, the cause of the characteristic failure of the switch element 407b is found. Cannot be observed with an optical microscope. Therefore, it is desirable that the charge collection electrode 407a be transparent so that the switch element 407b can be easily observed even after the charge collection electrode 407a is formed.

  The interlayer insulating film 420 is made of a photosensitive acrylic resin, and serves to electrically isolate the switch element 407b. A contact hole 421 passes through the interlayer insulating film 420, and the charge collection electrode 407 a is connected to the drain electrode 412. The contact hole 421 is formed in a reverse taper shape as shown in FIG.

  In the present embodiment, a high voltage power source (not shown) is connected between the bias electrode 401 and the Cs electrode 418, and the bias electrode 401 and the high voltage line 432 are electrically connected.

(Configuration in which the bias electrode 401 and the high voltage line 432 are electrically connected)
Here, the configuration in which the bias electrode 401 and the high voltage line 432 are electrically connected in the TFT radiation detector 400 according to the present embodiment will be described. FIG. 5 is a schematic plan view showing a connection portion where the extended electrode portion 431 and the high voltage line 432 are connected. FIG. 6 is a schematic side view showing a connection portion where the extended electrode portion 431 and the high voltage line 432 are connected.

  As shown in FIGS. 1 and 5, the TFT radiation detector 400 includes an extended electrode portion 431 that extends from the bias electrode 401 to a region without the photoconductive layer 404 on the glass substrate 408. The extension electrode portion 431 and the bias electrode 401 constitute an electrode layer 430 and are integrally formed in the same process.

  Note that the extension electrode portion 431 only needs to extend outside the detectable region (image acquisition region) where the radiation can be detected by the charge collection electrode 407a collecting the charge, and the region where the photoconductive layer 404 is located. The structure extended in this may be sufficient. Further, the extension electrode portion 431 and the bias electrode 401 may be formed in separate steps or may not be integrally formed.

  As shown in FIG. 1, the extended electrode portion 431 is pulled down to the glass substrate 408 corresponding to the lowest portion of the radiation detector 400 along the downwardly inclined side surface inclined downward of the photoconductive layer 404.

  The extended electrode portion 431 does not necessarily have to be pulled down by the glass substrate 408. For example, as shown in FIG. 7, the extended electrode portion 431 is formed of an insulating material or the like between the glass substrate 536 and the extended electrode portion 431. By providing the intermediate member 480, it may be configured to extend at the same height as the bias electrode 401. Further, the extended electrode portion 431 may be configured to extend at a position higher than the bias electrode 401, and further extended at an arbitrary height between the upper surface of the photoconductive layer 404 and the glass substrate 408. May be.

  As shown in FIG. 5, the extended electrode portion 431 protrudes from the corner portion of the bias electrode 401, extends obliquely, and extends to the corner portion of the radiation detector 400.

  The width of the extension electrode part 431 (the length in the direction (arrow Y direction in FIG. 5) perpendicular to the extension direction (arrow X direction in FIG. 5)) is formed narrower than the width of the bias electrode 401. Thereby, the material for forming the electrode layer 430 can be reduced.

  Note that the extension electrode portion 431 may have the same width as the bias electrode 401 or may be formed wider than the bias electrode 401. Further, the extended electrode portion 431 may be extended from the side portion (side edge) of the bias electrode 401.

  Further, as shown in FIGS. 1 and 5, the hole injection blocking layer 402 as an example of the intermediate layer is between the photoconductive layer 404 and the bias electrode 401 and between the extended electrode portion 431 and the glass substrate 408. It is formed over the glass substrate 408 and extends to a region without the photoconductive layer 404.

  The hole injection blocking layer 402 is directly formed on the glass substrate 408, and is also used as a base for bonding the extended electrode portion 431 to the glass substrate 408. As the hole injection blocking layer 402, rather than the adhesion between the extended electrode portion 431 and the glass substrate 408, the adhesion between the hole injection blocking layer 402 and the glass substrate 408 and the hole injection blocking layer 402 A material that enhances the adhesion between the extended electrode portion 431 is selected.

  In this way, by using the hole injection blocking layer 402 as the base, which has higher adhesion to the glass substrate 408 and the extended electrode part 431 than the adhesion of the extended electrode part 431 to the glass substrate 408, the extended electrode part The bonding force between 431 and the glass substrate 408 is increased.

  As shown in FIGS. 5 and 6, a high voltage line 432 as an example of an electric wire is electrically connected to the distal end portion of the extended electrode portion 431 by a conductive member 448 such as a conductive paste. Further, the high voltage line 432 is fixed on the glass substrate 408 by a fixing member 449 such as an adhesive.

  The high voltage line 432 electrically connected to the extension electrode portion 431 applies a bias voltage from the extension electrode portion 431 to the photoconductive layer 404 via the bias electrode 401.

  In FIG. 6, the hole injection blocking layer 402 is omitted.

(Structure that covers the connecting portion between the extended electrode portion 431 and the high voltage line 432 and the photoconductive layer 404)
Next, a configuration for covering the connection portion between the extended electrode portion 431 and the high voltage line 432 and the photoconductive layer 404 will be described. As shown in FIG. 1, a cover glass 440 as an example of a cover member that covers the bias electrode 401 is provided above the bias electrode 401.

The glass substrate 408 is provided with a protective member 442 to which the cover glass 440 is bonded.
The protective member 442 surrounds the periphery of the photoconductive layer 404, and is formed in a box shape with the upper and lower portions opened as a whole.

  Further, the protective member 442 has a side wall 442a erected on the outer peripheral portion of the glass substrate 408, and a flange portion 442b protruding from the upper part of the side wall 442a to the upper side of the central portion of the glass substrate 408. It is formed in an L shape.

  The cover glass 440 has an outer peripheral surface whose upper surface is joined to the lower surface (inner wall) of the flange portion 442b and is supported by the protective member 442.

  The joint between the protective member 442 and the cover glass 440 is disposed outside the photoconductive layer 404. That is, the protective member 442 and the cover glass 440 are bonded to each other in a region where the photoconductive layer 404 on the glass substrate 408 is not present, but not above the photoconductive layer 404.

  Note that an insulating member having an insulating property is used for the protective member 442. As the insulating member, for example, polycarbonate, polyethylene terephthalate (PET), polymethyl methacrylate (acrylic), or polyvinyl chloride is used.

  The protective member 442 has a lower opening closed by a glass substrate 408 and an upper opening closed by a cover glass 440, so that a space A having a predetermined size is formed in the protective member 442. The photoconductive layer 404 is accommodated in the space A, and the photoconductive layer 404 is covered with a cover glass 440, a glass substrate 408, and a protective member 442.

  As shown in FIG. 5, the protection member 442 is formed in a quadrangular shape with corners cut away in plan view (top view). A protective member 443 is provided to surround the notched portion of the protective member 442. Thereby, in the radiation detector 400, in addition to the space A surrounded by the protection member 442, a space B surrounded by the outer surface of the protection member 442 and the protection member 443 is formed.

  As described above, the space A and the space B are partitioned by the protection member 442 and the protection member 442 and are separated from each other, and are two regions that are spatially separated.

  The side wall 442d of the protection member 442 arranged between the space A and the space B functions as a partition wall that partitions the space A and the space B. Further, the space B does not have to be a corner (corner) of the radiation detector 400, but may be formed at the edge.

  The extension electrode portion 431 is configured to protrude into the space B toward the outside of the protection member 442, and the connection portion between the extension electrode portion 431 and the high voltage line 432 is accommodated in the space B. On the other hand, the photoconductive layer 404 is accommodated in the space A, and a detectable region in which the radiation can be detected by the charge collecting electrode 407a collecting the charge is formed in the space A.

  In the present embodiment, the first filler 444 is filled in the space A surrounded by the cover glass 440, the protective member 442, and the glass substrate 408.

  The transmittance of radiation (X-rays) is better when the atomic weight is smaller than when the atomic weight is large. Therefore, in the present embodiment, as the first filler 444, a filler composed of an element having an atomic number of 9 (F) or less, that is, an element having an atomic weight of atomic number 9 or less of fluorine (F) is used. Specifically, for example, an epoxy room temperature curable resin is used as the first filler 444.

  In addition, even if an element having an atomic number of 10 (Ne) or more is included, it is within the technical scope of the present application if it is 5% by weight or less.

  In the present embodiment, the first filler 444 is a filler different from the second filler 445 shown below, and has better radiation (X-ray) transmittance than the second filler 445. Things are used.

  On the other hand, a space B surrounded by the outer surface of the protective member 442 and the protective member 443 is filled with a second filler 445 as an elastic filler having elasticity.

  As the second filler 445, a filler having an elongation at break of 120% or more and 500% or less is used. Specifically, as the second filler 445, for example, a silicone resin or a modified silicone adhesive is used. Used. Examples of the modified silicone adhesive include Cemedine Super X (registered trademark (manufactured by Cemedine Co., Ltd.)), TSE392 (manufactured by Momentive Performance Materials Japan GK), MOS-7 (registered trademark (manufactured by Konishi Co., Ltd.)). )) 1200 series (manufactured by ThreeBond Co., Ltd.) can be used.

  JIS K 6251 is used as a method for measuring elongation at break.

  In the present embodiment, the second filler 445 is a filler different from the first filler 444, and has a higher elongation at break than the first filler 444 and is excellent in quick drying. ing.

  In addition, when a conductive paste is used for the conductive member 448, the second filler 445 is selected such that the conductive paste does not melt and diffuse into the second filler 445. The second filler 445 is selected so that the insulation performance is not significantly reduced by moisture absorption.

  Further, in the space B, as shown in FIG. 6, an insulating member 482 made of a film material such as polyethylene terephthalate (PET) is covered on the upper surface of the second filler 445, and the dielectric breakdown upwards Is suppressed.

(Manufacturing process of TFT radiation detector 400)
Here, an example of a manufacturing process of the TFT radiation detector 400 will be schematically described.

First, an electron injection blocking layer 406 made of antimony sulfide (Sb ₂ S ₃ ) having a thickness of 2 μm is formed on the active matrix substrate 450. Next, a Se raw material is deposited by vapor deposition to form a photoconductive layer 404 made of amorphous Se having a thickness of 1000 μm.

Next, a hole injection blocking layer 402 made of antimony sulfide (Sb ₂ S ₃ ) having a thickness of 0.3 μm is formed on the photoconductive layer 404. Next, Au is deposited by vapor deposition to form an electrode layer 430 including a bias electrode 401 and an extended electrode portion 431 having a thickness of 0.1 μm.

  Next, the protective member 442 is attached on the outer periphery of the glass substrate 408, and the cover glass 440 is attached to the protective member 442.

  Next, the first filler 444 is filled into the space A surrounded by the cover glass 440, the protective member 442, and the glass substrate 408 through a hole (not shown).

  Then, at the end of the manufacturing process of the radiation detector 400, the high voltage line 432 is electrically connected to the extension electrode portion 431, the space B is filled with the second filler 445, and the radiation detector 400 is manufactured.

(Operation principle of TFT radiation detector)
Next, the operation principle of the above-described TFT radiation detector 400 will be described. When the photoconductive layer 404 is irradiated with X-rays, charges (electron-hole pairs) are generated in the photoconductive layer 404. In a state where a voltage is applied between the bias electrode 401 and the Cs electrode 418, that is, in a state where a voltage is applied to the photoconductive layer 404 via the bias electrode 401 and the Cs electrode 418, charge accumulation with the photoconductive layer 404 is performed. Since the capacitor 407c is electrically connected in series, the electrons generated in the photoconductive layer 404 move to the + electrode side, and the holes move to the-electrode side. As a result, the charge storage capacitor Charge is accumulated in 407c.

  The charge stored in the charge storage capacitor 407c can be taken out through the source electrode 410 by turning on the switch element 407b by an input signal to the gate electrode 411. Since the electrode wiring composed of the gate electrode 411 and the source electrode 410, the switch element 407b, and the charge storage capacitor 407c are all provided in a matrix, signals input to the gate electrode 411 are sequentially scanned to obtain the source electrode 410. By detecting the signal from each source electrode 410, X-ray image information can be obtained two-dimensionally.

(Effects of TFT radiation detector)
Next, operational effects of the above-described TFT radiation detector 400 will be described.

  In the present embodiment, the first filler 444 filled in the detectable region is composed of an element having an atomic number of 9 or less, and therefore, compared with a case where it is composed of an element exceeding the atomic number 9, Good permeability. For this reason, the radiation detection sensitivity can be maintained in the detectable region. In the case of a filler composed of an element having an atomic number of 9 or more, the radiation transmission is poor and the required radiation sensitivity may not be obtained.

  In addition, since the connection portion where the bias electrode 401 and the electric wire are connected is filled with the second filler 445 having elasticity, the extension electrode portion 431 and the high-voltage wire are compared with the curable filler. Adhesion with 432 can be maintained, and peeling between the high voltage line 432 and the extended electrode portion 431 can be suppressed.

  As described above, in the present embodiment, the high voltage line is maintained while maintaining the radiation detection sensitivity by properly using the filler in the connection part and the detectable region where the extension electrode part 431 and the high voltage line 432 are connected. Detachment between 432 and the electrode portion is suppressed.

  Further, since the second filler 445 has a quicker drying property than the first filler 444, the manufacturing time can be shortened in the final process of manufacturing the radiation detector 400 filled with the second filler 445.

  In the present embodiment, the connection between the high voltage line 432 and the extended electrode portion 431 is performed in the space B where the detectable region is formed and the space A in which the photoconductive layer 404 is accommodated. In the final manufacturing process of the radiation detector 400, the high voltage line 432 and the extended electrode portion 431 can be connected, and until the final manufacturing process of the radiation detector 400, the bias voltage is applied to the photoconductive layer 404. The high voltage line 432 does not get in the way.

  In the configuration of the present embodiment, the hole injection blocking layer 402 is formed between the photoconductive layer 404 and the bias electrode 401 and between the extended electrode portion 431 and the glass substrate 408. The adhesion between the portion 431 and the glass substrate 408 is improved.

  When Au or the like is used for the electrode layer 430, the adhesion with the glass substrate 408 is poor, but the hole injection blocking layer 402 improves the adhesion between the extended electrode portion 431 and the glass substrate 408 as described above. Accordingly, peeling between the extended electrode portion 431 and the glass substrate 408 can be suppressed. In addition, by using the hole injection blocking layer 402, only the existing layer structure is peeled off without forming a new member on the glass substrate 408 to increase the bonding force between the extended electrode portion 431 and the glass substrate 408. Therefore, the number of parts and the manufacturing process do not increase.

(Configuration of optical reading radiation detector)
The present invention can also be applied to an optical reading type radiation detector, and is applied according to the configuration of the photoconductive layer 404 in the radiation detector 400 described above. Here, a radiation detection substrate 500 as an optical reading type radiation detector will be described.

  8A and 8B are schematic views of the radiation detection substrate 500. FIG. As shown in FIGS. 8A and 8B, the radiation detection substrate 500 is connected with a TCP 510, a readout device 512 connected thereto, and a high voltage line 514 for applying a high voltage.

  A TCP (Tape Carrier Package) 510 is a flexible wiring board on which a signal detection IC (charge amplifier IC) 511 is mounted. The TCP 510 is connected by thermocompression bonding using an ACF (Anisotropic Conductive Film).

  An extended electrode portion 519 extending from the upper electrode 518 above the detection area 516 is formed, and a high voltage line 514 is connected to the extended electrode portion 519 by a conductive member 580 such as a conductive paste. The detection area 516 for detecting radiation includes a lower electrode 520 for reading signals and applying a high voltage, a radiation detection layer 522 for converting radiation into charges, and an upper electrode 518 for applying a high voltage.

  The lower electrode 520 is provided on the glass substrate 536, and the radiation detection lower substrate 524 is configured by the glass substrate 536 provided with the lower electrode 520.

  The production of the radiation detection substrate 500 is roughly divided into the production of a radiation detection lower substrate 524 including the lower electrode 520, the formation of the radiation detection layer 522 and the upper electrode 518, and the connection of the high voltage line 514.

  Hereinafter, the structure of the radiation detection lower substrate 524 will be described. FIG. 9 shows a schematic structure of the radiation detection lower substrate 524. In FIG. 9, TCP510 is simplified to one channel on the left and three channels on each side, for a total of 6 channels. The radiation detection lower substrate 524 includes a radiation detection unit 526, a pitch conversion unit 528, and a TCP connection unit 530 as shown in FIG.

  In the radiation detection unit 526, lower electrodes 520 for extracting signals are arranged in a stripe shape (line shape). In addition, a color filter layer 534 that partially transmits only light having an arbitrary wavelength is formed under the transparent organic insulating layer 532.

  The layer above the color filter layer 534 is referred to as a common B line 520B, and the signal S line 520S in a portion without the color filter layer 534. The B line 520B is shared outside the radiation detection unit and has a comb electrode structure. The S line 520S is used as a signal line. The width of the B line 520B is, for example, 20 μm, the width of the S line 520S is, for example, 10 μm, and the interval between the B line 520B and the S line 520S is, for example, 10 μm.

  The width of the color filter layer 534 is, for example, 30 μm. The lower electrode 520 is transparent to irradiate light from the back surface, and needs flatness to avoid breakdown due to electric field concentration when a high voltage is applied. For example, IZO or ITO is used. When IZO is used, the thickness is 0.2 μm and the flatness is about Ra = 1 nm.

  The color filter layer 534 is a photosensitive resist in which a pigment is dispersed, for example, a red resist used for an LCD color filter. In order to eliminate the level difference of the color filter layer 534, a photosensitive organic transparent insulating layer 532 such as PMMA is used.

  Further, the glass substrate 536 serving as a support member is preferably transparent and rigid, and more preferably soda lime glass. As an example of the thickness of each layer, the lower electrode 520 is 0.2 μm, the color filter layer 534 is 1.2 μm, the organic transparent insulating layer 532 is 1.8 μm, and the glass substrate 536 is 1.8 mm. The color filter layer 534 and the organic insulating layer 532 are provided only in the radiation detection unit 526, and the boundary is in the radiation detection unit 526 and the pitch conversion unit 528. For this reason, the IZO wiring is formed on the glass substrate 536 in the TCP connection portion 530 via the boundary step portion of the organic insulating layer 532.

  In the radiation detection unit 526, wiring is taken out to the left and right TCPs 510 in units of a certain number. In FIG. 9, it is a unit of 3 lines. An example of the number of lines is 256 lines. The line width in the radiation detection unit 526 is different from the line width in the TCP connection unit 530 and is adjusted, and the line width is adjusted in the pitch conversion unit 528 in order to route the wiring to a predetermined TCP connection position. The B line 520B is made common and similarly drawn out to the TCP connection unit 530.

  In the TCP connection unit 530, the signal S line 520S and the common B line 520B shared by the outside of the radiation detection unit are arranged. The common B line 520B is disposed outside the signal S line 520S. As an example of the number, the signal line 256 and the common line are connected to the TCP using five lines above and below. The electrode line / space is 40/40 μm.

  In addition, an alignment mark for TCP is necessary to connect TCP with this TCP connection unit 530. Although it is desirable to form with a transparent electrode, it is difficult to recognize because it is transparent, and an alignment mark is formed using, for example, a color filter layer 534 that is a constituent member of this substrate as an opaque material.

  Next, the radiation detection layer 522 will be described. FIG. 10 is a schematic diagram schematically showing the configuration of the radiation detection substrate 500. As shown in FIG. 10, the radiation detection layer includes a recording photoconductive layer 542, a charge storage layer 544, a reading photoconductive layer 546, an electrode interface layer 548, an undercoat layer 550, and an overcoat layer 552. ing.

<Photoconductive layer for recording>
The recording photoconductive layer 542 is a photoconductive material that absorbs electromagnetic waves and generates charges, and is an amorphous selenium compound, Bi ₁₂ MO ₂₀ (M: Ti, Si, Ge), Bi ₄ M ₃ O ₁₂ (M: Ti Si, Ge), Bi ₂ O ₃ , BiMO ₄ (M: Nb, Ta, V), Bi ₂ WO ₆ , Bi ₂₄ B ₂ O ₃₉ , ZnO, ZnS, ZnSe, ZnTe, MNbO ₃ (M: Li, Na, K), PbO, HgI ₂ , PbI ₂ , CdS, CdSe, CdTe, BiI ₃ , GaAs, and the like. Of these, an amorphous selenium compound is particularly preferable.

  In the case of an amorphous selenium compound, the layer is doped with a small amount of alkali metal such as Li, Na, K, Cs, Rb between 0.001 ppm and 1 ppm, LiF, NaF, KF, CsF, RbF, etc. A small amount of 10 to 10,000 ppm of fluoride, P, As, Sb, Ge added between 50 ppm and 0.5%, As doped from 10 ppm to 0.5%, Cl, Br , I doped in a slight amount between 1 ppm and 100 ppm can be used.

  In particular, amorphous selenium containing about 10 ppm to 200 ppm of As, amorphous selenium containing about 0.2% to 1% of As and further containing 5 ppm to 100 ppm of Cl, and alkali metal of about 0.001 ppm to 1 ppm were contained. Amorphous selenium is preferably used.

Also, Bi ₁₂ MO ₂₀ (M: Ti, Si, Ge), Bi ₄ M ₃ O ₁₂ (M: Ti, Si, Ge), Bi ₂ O ₃ , BiMO ₄ (M: Nb, Ta, V), Bi ₂ WO ₆ , Bi ₂₄ B ₂ O ₃₉ , ZnO, ZnS, ZnSe, ZnTe, MNbO ₃ (M: Li, Na, K), PbO, HgI ₂ , PbI ₂ , CdS, CdSe, CdTe Those containing fine particles of a photoconductive substance such as BiI ₃ or GaAs can also be used.

  The thickness of the recording photoconductive layer 542 is preferably 100 μm or more and 2000 μm or less in the case of amorphous selenium. In particular, it is particularly preferably in the range of 150 μm or more and 250 μm or less for mammography, and in the range of 500 μm or more and 1200 μm or less for general photographing applications.

<Charge storage layer>
The charge storage layer 544 may be any film that is insulative with respect to the polar charge to be stored, such as an acrylic organic resin, polyimide, BCB, PVA, acrylic, polyethylene, polycarbonate, polyetherimide, or a polymer such as As ₂ S. ₃ , sulfides such as Sb ₂ S ₃ and ZnS, oxides and fluorides. Furthermore, it is more preferable to be insulative with respect to the charge of the polarity to be accumulated, and to be conductive with respect to the charge with the opposite polarity. Substances with differences are preferred.

Preferable compounds include As ₂ Se ₃ , As ₂ Se ₃ doped with Cl, Br, I from 500 ppm to 20000 ppm, and As ₂ Se ₃ Se ₂ substituted with Te to about 50% (Se _x Te _1-x ) ₃ (0.5 <x <1), As ₂ Se ₃ with Se replaced to about 50%, As _x Se _y with As concentration changed by ± 15% from As ₂ Se ₃ ( x + y = 100, 34 ≦ x ≦ 46), an amorphous Se—Te system containing 5-30 wt% Te.

  In the case of using such a substance containing a chalcogenide element, the thickness of the charge storage layer 544 is preferably 0.4 μm to 3.0 μm, more preferably 0.5 μm to 2 μm. Such a charge storage layer 544 may be formed by a single film formation or may be laminated in a plurality of times.

  As a preferable charge storage layer 544 using an organic film, a compound obtained by doping a charge transport agent with a polymer such as an acrylic organic resin, polyimide, BCB, PVA, acrylic, polyethylene, polycarbonate, or polyetherimide is preferably used. . Preferred charge transport agents include tris (8-quinolinolato) aluminum (Alq3), N, N-diphenyl-N, N-di (m-tolyl) benzidine (TPD), polyparaphenylene vinylene (PPV), polyalkylthiophene. , Polyvinylcarbazole (PVK), triphenylene (TNF), metal phthalocyanine, 4- (dicyanomethylene) -2-methyl-6- (p-dimethylaminostyryl) -4H-pyran (DCM), liquid crystal molecules, hexapentyloxytriphenylene And a molecule selected from the group consisting of a discotic liquid crystal molecule having a central core containing a π-conjugated condensed ring or a transition metal, a carbon nanotube, and fullerene. The doping amount is set between 0.1 and 50 wt.%.

<Reading photoconductive layer>
The photoconductive layer for reading 546 is a photoconductive material that absorbs electromagnetic waves, particularly visible light, and generates electric charge. The energy gap of amorphous selenium compound, amorphous Si: H, crystalline Si, GaAs, etc. is in the range of 0.7-2.5 eV. The semiconductor substance contained in the can be used. In particular, amorphous selenium is preferable.

In the case of an amorphous selenium compound, the layer is doped with a small amount of alkali metal such as Li, Na, K, Cs, Rb between 0.001 ppm and 1 ppm, LiF, NaF, KF, CsF, RbF, etc. A small amount of fluoride of 10ppm to 10000ppm, P, As, Sb, Ge added from 50ppm to 0.5%, As doped from 10ppm to 0.5%, Cl, Br , I doped in a slight amount between 1 ppm and 100 ppm can be used.
In particular, amorphous selenium containing about 10 ppm to 200 ppm of As, amorphous selenium containing about 0.2% to 1% of As and further containing 5 ppm to 100 ppm of Cl, and alkali metal of about 0.001 ppm to 1 ppm were contained. Amorphous selenium is preferably used.

  The thickness of the reading photoconductive layer 546 is not limited as long as it can sufficiently absorb the reading light and the electric field generated by the charges accumulated in the charge storage layer 544 can drift the photoexcited charge, and is preferably about 1 μm to 30 μm.

<Electrode interface layer>
The electrode interface layer 548 is laid between the recording photoconductive layer 542 and the upper electrode 518 or between the reading photoconductive layer 546 and the lower electrode 520. For the purpose of preventing crystallization, amorphous selenium with As added in the range of 1% -20%, S, Te, P, Sb, Ge added in the range of 1% to 10%, the above What added the combination of an element and another element is preferable.

Alternatively, As ₂ S ₃ and As ₂ Se ₃ having a higher crystallization temperature can also be preferably used. Furthermore, in addition to the above-mentioned additive elements for the purpose of preventing charge injection from the electrode layer, in particular, alkali metals such as Li, Na, K, Rb, Cs, LiF, NaF, KF to prevent hole injection It is also preferable to dope a molecule such as RbF, CsF, LiCl, NaCl, KCl, RbF, CsF, CsCl, CsBr in the range of 10 ppm to 5000 ppm. Conversely, in order to prevent electron injection, it is also preferable to dope a halogen element such as Cl, I, or Br, or a molecule such as In ₂ O _{3 in} the range of 10 ppm to 5000 ppm. The thickness of the interface layer is preferably set between 0.05 μm and 1 μm so as to sufficiently fulfill the above purpose.

The electrode interface layer 548, the reading photoconductive layer 546, the charge storage layer 544, and the recording photoconductive layer 542 have a substrate temperature of 25 ° C. or higher in a vacuum chamber having a degree of vacuum of 10 ⁻³ to 10 ⁻⁷ Torr. The boat or crucible containing each of the above alloys is kept at a temperature of 70 ° C. or lower and heated by resistance heating or electron beam to evaporate or sublimate the alloy or compound, and are laminated on the substrate.

When the evaporation temperatures of the alloy and the compound are greatly different, it is also preferable to control the addition concentration and the dope concentration by simultaneously heating and individually controlling a plurality of boats corresponding to a plurality of evaporation sources. For example, As ₂ Se ₃ / Amorphous selenium / LiF are put in a boat, As ₂ Se ₃ boat is 340 ° C, Amorphous selenium (a-Se) boat is 240 ° C, LiF boat is 800 ° C, and each boat By opening and closing the shutter, a layer of As10% doped amorphous selenium doped with 5000 ppm LiF can be formed.

<Underlayer>
An undercoat layer 550 can be provided between the reading photoconductive layer 546 and the lower electrode (charge collecting electrode) 520. When there is an electrode interface layer (crystallization prevention layer (A layer)) 548, it is preferably provided between the electrode interface layer 548 and the lower electrode 520. The undercoat layer 550 preferably has rectification characteristics from the viewpoint of reducing dark current and leakage current. It is preferable to have an electron blocking property when a positive bias is applied to the upper electrode 518 and a hole blocking property when a negative bias is applied.

The resistivity of the undercoat layer is preferably 10 ⁸ Ωcm or more, and the film thickness is preferably 0.01 μm to 10 μm. As a layer having an electron blocking property, that is, an electron injection blocking layer, a layer made of a composition such as Sb ₂ S ₃ , Sb ₂ Te ₃ , ZnTe, CdTe, As ₂ Se ₃ , As ₂ S ₃ , or an organic polymer layer Is preferred. As the organic polymer layer, a film in which NPD or TPD is mixed with a hole transporting polymer such as PVK or an insulating polymer such as polycarbonate, polystyrene, polyimide, or polycycloolefin can be preferably used.

As a layer having a hole blocking property, that is, a hole injection blocking layer, a film of CdS, CeO ₂ , or the like, or an organic polymer layer is preferable. The organic polymer layer, polycarbonate, polystyrene, polyimide, the insulating polymer polycycloolefin or the like, C _{60 (fullerene),} can be preferably used a film obtained by mixing carbon clusters such as C _70.

  On the other hand, a thin insulating polymer layer can also be preferably used. For example, parylene, polycarbonate, PVA, PVP, PVB, a polyester resin, an acrylic resin such as polymethyl methacrylate is preferable. The film thickness at this time is preferably 2 μm or less, and more preferably 0.5 μm or less.

<Upper layer>
An overcoat layer 552 can be provided between the recording photoconductive layer 542 and the upper electrode (voltage application electrode) 518. When there is an electrode interface layer (crystallization prevention layer (C layer)) 548, it is preferably provided between the electrode interface layer 548 and the upper electrode 518. The overcoat layer 552 preferably has rectification characteristics from the viewpoint of reducing dark current and leakage current.

It is preferable to have a hole blocking property when a positive bias is applied to the upper electrode 518, and an electron blocking property when a negative bias is applied. The resistivity of the overcoat layer is preferably 10 ⁸ Ωcm or more, and the film thickness is preferably 0.01 μm to 10 μm.

As a layer having an electron blocking property, that is, an electron injection blocking layer, a layer made of a composition such as Sb ₂ S ₃ , SbTe, ZnTe, CdTe, SbS, AsSe, As ₂ S ₃ or an organic polymer layer is preferable. As the organic polymer layer, a film in which NPD or TPD is mixed with a hole transporting polymer such as PVK or an insulating polymer such as polycarbonate, polystyrene, polyimide, or polycycloolefin can be preferably used.

As a layer having a hole blocking property, that is, a hole injection blocking layer, a film of CdS, CeO ₂ , or the like, or an organic polymer layer is preferable. The organic polymer layer, polycarbonate, polystyrene, polyimide, the insulating polymer polycycloolefin or the like, C _{60 (fullerene),} can be preferably used a film obtained by mixing carbon clusters such as C _70.

  On the other hand, a thin insulating polymer layer can also be preferably used. For example, parylene, polycarbonate, PVA, PVP, PVB, a polyester resin, an acrylic resin such as polymethyl methacrylate is preferable. The film thickness at this time is preferably 2 μm or less, and more preferably 0.5 μm or less.

  Next, the upper electrode 518 and the surface protective layer 554 formed on the surface of the upper electrode 518 will be described.

<Upper electrode>
As the upper electrode 518 formed on the upper surface of the recording photoconductive layer 542, a metal thin film is preferably used. Materials include Au, Ni, Cr, Au, Pt, Ti, Al, Cu, Pd, Ag, Mg, MgAg3-20% alloy, Mg-Ag intermetallic compound, MgCu3-20% alloy, Mg-Cu metal What is necessary is just to make it form from metals, such as an intermetallic compound.

  In particular, Au, Pt, and Mg—Ag intermetallic compounds are preferably used. For example, when Au is used, the thickness is preferably 15 nm to 200 nm, more preferably 30 nm to 100 nm. For example, when an MgAg3-20% alloy is used, it is more preferable to use a thickness of 100 nm to 400 nm.

Although the preparation method is arbitrary, it is preferably formed by vapor deposition by a resistance heating method.
For example, after a metal lump is melted in a boat by a resistance heating method, the shutter is opened, vapor deposition is performed for 15 seconds, and cooling is performed once. It is formed by repeating a plurality of times until the resistance value becomes sufficiently low.

<Surface protective layer>
In order to form a latent image on the radiation detection device by irradiation, a high voltage of several kV is applied to the upper electrode 518. If the upper electrode 518 is open to the atmosphere, creeping discharge is generated, and there is a risk of electric shock of the subject. In order to prevent creeping discharge in the upper electrode 518, a surface protective layer 554 is formed on the upper surface of the electrode and subjected to insulation treatment.

  Insulation treatment requires a structure in which the electrode surface does not come into contact with the atmosphere at all, and a structure in which the electrode surface is tightly covered with an insulator. In addition, this insulator needs to have a dielectric breakdown strength exceeding the applied potential. Furthermore, it is necessary for the function of the radiation detection device to be a member that does not interfere with radiation transmission. As a material and a production method of these required covering properties, dielectric breakdown strength and radiation transmittance, vapor deposition of insulating polymer or solvent coating is preferable.

  Specific examples include a room temperature curing type epoxy resin, a polycarbonate resin, a polyvinyl butyral resin, a polyvinyl alcohol resin, an acrylic resin, and a method of forming a polyparaxylylene derivative by a CVD method. Among these, a room temperature curing type epoxy resin and polyparaxylylene are preferably formed by a CVD method, and a method of forming a polyparaxylylene derivative by a CVD method is particularly preferable. A preferable film thickness is 10 μm or more and 1000 μm or less, and more preferably 20 μm or more and 100 μm or less.

  A polyparaxylylene film can be formed at room temperature, so that an insulating film with extremely high step coverage can be obtained without applying thermal stress to the adherend, but it is chemically very stable. In general, the adhesion is often not preferred. In order to increase the adhesion with the adherend, as a treatment to the adherend before the formation of polyparaxylylene, physical, such as a coupling agent, corona discharge, plasma treatment, ozone cleaning, acid treatment, surface treatment, Chemical treatment is generally known and can be used. In particular, a polyparaxylylene film is formed after applying a silane coupling agent or a solution obtained by diluting a silane coupling agent with an alcohol or the like if necessary to at least improve the adhesion to the adherend. A method of improving the adhesion with the adherend is preferable.

  Furthermore, it is preferable to perform a moisture-proof treatment to prevent the radiation detection device from aging. Specifically, the structure is covered with a moisture-proof member. As the moisture-proof member, a resin alone such as the insulating polymer is insufficient in function, and a configuration having at least an inorganic material layer such as glass or an aluminum laminate film is effective. However, since glass attenuates radiation transmission, the moisture-proof member is preferably a thin aluminum laminate film. For example, as an aluminum laminate film generally used as a moisture-proof packaging material, there is a laminate of PET 12 μm / rolled aluminum 9 μm / nylon 15 μm.

  The thickness of aluminum is preferably 5 μm or more and 30 μm or less, and the front and rear PET thicknesses and nylon thicknesses are each preferably 10 μm or more and 100 μm or less. The X-ray attenuation of this film is about 1%, which is optimal as a member that achieves both a moisture-proof effect and X-ray transmission.

  For example, as shown in FIG. 11, the entire surface of the radiation detection device subjected to insulation treatment with polyparaxylylene 554A is covered with a moisture-proof film 554B, and the periphery of the moisture-proof film 554B is bonded and fixed to the substrate with an adhesive outside the radiation detection device region. To do. Thus, the radiation detection device is sealed with the substrate and the moisture-proof film 554B.

  At the time of this adhesion and fixation, polyparaxylylene 554A is chemically very stable, and therefore generally has poor adhesion to other members by an adhesive, but light irradiation treatment with ultraviolet light prior to adhesion is performed. The adhesion can be improved by applying. The necessary irradiation time is appropriately adjusted to the optimum time depending on the wavelength and wattage of the ultraviolet light source to be used, but it is preferably 1 to 50 W with a low-pressure mercury lamp, and the light irradiation is preferably performed for 1 to 30 minutes.

  In addition, the radiation detection device according to the present embodiment uses amorphous selenium, and amorphous selenium may crystallize at a high temperature of 40 ° C. or higher, so that the function of forming a latent image may not be obtained. Heat treatment is not suitable. Therefore, a room temperature curable adhesive is desirable, and a two-component mixed room temperature curable epoxy adhesive having a high adhesive strength is optimal. This epoxy adhesive is applied to the outer periphery of the radiation detection device and covered with a moisture-proof film 554B. The adhesive portion is pressed and fixed uniformly from the upper surface of the moisture-proof film 554B, and is left in this state for 12 hours or more in a room temperature environment to be cured. After the adhesive is cured, the pressure is released to complete the sealing structure.

  It supplements about a sealing structure member. When a radiation detection device is used for mammography, imaging detection with a low dose is desired in order to suppress exposure in X-ray imaging. In order to detect a change in shadow caused by low-dose irradiation, it is desirable that members other than the subject (mammo) in the path from the radiation source to the device have a high X-ray transmittance, thereby obtaining a clear image.

  Although an example of a preferable protective layer / sealing structure is shown in FIG. 11, it is not limited to this. It is preferable to maintain the humidity environment of the device at 30% or less, more preferably 10% or less by forming the protective film.

  Hereinafter, although the example of a preferable layer structure is shown, this invention is not a thing limited to this. A model diagram of the cross section is shown in FIG.

<Configuration 1>
A layer structure was fabricated on the radiation detection lower substrate 524 as shown in FIGS. 8 and 9 in the following order. As the lower electrode 520, a flat IZO electrode having a surface roughness Ra <1 nm was used.
Undercoat layer 550: CeO ₂ thickness 20 nm
Lower electrode interface layer 548: As10% doped amorphous selenium: LiF500ppm doped, thickness 0.1μm
Photoconductive layer for reading 546: amorphous selenium, thickness 7 μm
Charge storage layer 544: As ₂ Se ₃ , thickness 1 μm
Photoconductive layer 542 for recording: 0.001 ppm of amorphous selenium Na, thickness 200 μm
Upper electrode interface layer 548: As10% doped amorphous selenium, thickness 0.2 μm
Overcoat layer 552: Sb ₂ S ₃ , thickness 0.5 μm
Upper electrode 518: Au, thickness 70 nm

<Configuration 2>
A layer structure was fabricated on the radiation detection lower substrate 524 as shown in FIGS. 8 and 9 in the following order. As the lower electrode 520, a flat IZO electrode having a surface roughness Ra <1 nm was used.
Undercoat layer 550: None Lower electrode interface layer 548: As3% doped amorphous selenium, thickness 0.15 μm
Photoconductive layer for reading 546: amorphous selenium, thickness 15 μm
Charge storage layer 544: As ₂ Se ₃ , thickness 2 μm
Photoconductive layer 542 for recording: containing 0.001 ppm of amorphous selenium Na, thickness 180 μm
Upper electrode interface layer 548: As10% doped amorphous selenium, thickness 0.1 μm
Overcoat layer 552: Sb ₂ S ₃ , thickness 0.2 μm
Upper electrode 518: Au, thickness 150 nm

<Configuration 3>
A layer structure was fabricated on the radiation detection lower substrate 524 as shown in FIGS. 8 and 9 in the following order. As the lower electrode 520, a flat IZO electrode having a surface roughness Ra <1 nm was used.
Undercoat layer 550: CeO ₂ , thickness 30 nm
Lower electrode interface layer 548: As 6% doped amorphous selenium, thickness 0.25 μm
Photoconductive layer for reading 546: amorphous selenium, thickness 10 μm
Charge storage layer 544: As ₂ Se ₃ , thickness 0.6 μm
Photoconductive layer 542 for recording: 0.001 ppm of amorphous selenium Na, thickness 230 μm
Upper electrode interface layer 548: As10% doped amorphous selenium, thickness 0.3 μm
Overcoat layer 552: Sb ₂ S ₃ , thickness 0.3 μm
Upper electrode 518: Au, thickness 100 nm

<Charge extraction amplifier>
In the present embodiment, the charge is A / D converted after being amplified through an amplifier. FIG. 12 is a block diagram showing the configuration of the charge extraction amplifier and the connection mode between the charge extraction amplifier and the image processing apparatus 150 arranged outside the radiation detection substrate 500.

  The charge amplifier IC 511 as a charge extraction amplifier is a multiplexer that multiplexes a number of charge amplifiers 33a and sample hold (S / H) 33b connected to each element 15a of the radiation detection substrate 500, and a signal from each sample hold 33b. 33c.

  The current flowing out from the lower electrode is converted into a voltage by each charge amplifier 33a, the voltage is sampled and held at a predetermined timing by the sample hold 33b, and the voltage corresponding to each sampled and held element 15a is switched in the arrangement order of the elements 15a. Are sequentially output from the multiplexer 33c (corresponding to a part of main scanning).

  The signals sequentially output from the multiplexer 33c are input to the multiplexer 31c provided on the printed circuit board 31. Further, the voltage corresponding to each element 15a is sequentially output from the multiplexer 31c so as to be switched in the arrangement order of the elements 15a, and the main scanning is completed. To do.

  The signals sequentially output from the multiplexer 31c are converted into digital signals by the A / D converter 31a, and the digital signals are stored in the memory 31b. The image signal once stored in the memory 31b is sent to an external image processing device 150 via a signal cable, and appropriate image processing is performed in the image processing device 150, and the image signal is uploaded to the network 151 together with the photographing information, and the server Or it is sent to a printer.

<Image acquisition sequence>
The image forming sequence of this image recording / reading system basically includes the process of irradiating recording light (for example, X-rays) while applying a high voltage and accumulating latent image charges, and irradiating the reading light after completing the application of high voltage. Then, it consists of a process of reading out the latent image charge. As the reading light L, a method of scanning the line light source 301 in the electrode direction (see FIG. 13) is optimal, but other methods are also possible.

  Furthermore, a process of sufficiently erasing the unread latent image charges can be combined as necessary. This erasing process is performed by irradiating the entire surface of the panel with erasing light. The entire surface may be irradiated at once, or line light or spot light may be scanned over the entire surface, after the reading process, and / or This is performed before the latent image accumulation process. When irradiating the erasing light, erasing efficiency can be increased by combining high voltage application. Further, by performing “pre-exposure” after applying a high voltage and before irradiating the recording light, it is possible to erase a charge (dark current charge) due to a dark current generated when a high voltage is applied.

  Furthermore, it is known that various charges are accumulated on the electrostatic recording medium before irradiation of recording light due to causes other than these. Since these residual signals affect the image information signal to be output next as an afterimage phenomenon, it is desirable to reduce them by correction.

  As a method of correcting the afterimage signal, a method of adding an afterimage reading process to the above-described image recording and reading process is effective. This afterimage recording process is performed by applying a high voltage without irradiating the recording light and then reading the “afterimage” with the reading light. The afterimage signal can be corrected by subtracting it from the signal. The afterimage reading process is performed before or after the image recording reading process. Further, an appropriate erasing process can be combined before or after the afterimage reading process.

  In the radiation detection substrate 500 as an optical reading type radiation detector, the upper electrode 518 corresponds to the upper electrode portion of the present invention, the radiation detection layer 522 corresponds to the charge conversion layer according to the present invention, and the lower electrode 520. Corresponds to the lower electrode portion according to the present invention. Further, the radiation detection lower substrate 524 corresponds to the substrate according to the present invention, and the high voltage line 514 corresponds to the electric wire according to the present invention.

  Similar to the radiation detector 400 described above, the optical reading radiation detection substrate 500 can be configured as follows.

  The radiation detection substrate 500 includes a protective member 523 surrounding the radiation detection layer 522. As shown in FIG. 14, the protection member 523 is formed in a quadrangular shape with corners cut away in plan view (top view). A protective member 572 is provided to surround the cut-out portion of the protective member 523. Accordingly, as shown in FIGS. 14 and 15, the radiation detection substrate 500 includes a space B surrounded by the outer surface of the protection member 523 and the protection member 572 in addition to the space A surrounded by the protection member 523. Is formed.

  As described above, the space A and the space B are partitioned by the protection member 523 and the protection member 523, are separated from each other, and are two regions that are spatially separated.

  The side wall 523d of the protection member 523 arranged between the space A and the space B functions as a partition wall that partitions the space A and the space B. Further, the space B does not have to be a corner (corner) of the radiation detection substrate 500, but may be formed at the edge.

The extension electrode portion 519 is configured to protrude into the space B toward the outside of the protective member 523, and the connection portion between the extension electrode portion 519 and the high voltage line 514 is accommodated in the space B.
On the other hand, in the space A, a radiation detection layer 522 is accommodated, and a detectable region in which radiation can be detected by the lower electrode 520 collecting charges is formed in the space A.

  In the radiation detection substrate 500, the space A surrounded by the protective member 523 and the radiation detection lower substrate 524 is filled with the first filler 576.

  The transmittance of radiation (X-rays) is better when the atomic weight is smaller than when the atomic weight is large. Therefore, in the present embodiment, as the first filler 576, a filler composed of an element having an atomic number of 9 (F) or less, that is, an element having an atomic weight of atomic number 9 or less of fluorine (F) is used. Specifically, for example, an epoxy room temperature curable resin is used as the first filler 576.

  In addition, even if an element having an atomic number of 10 (Ne) or more is included, it is within the technical scope of the present application if it is 5% by weight or less.

  Further, in the radiation detection substrate 500, the first filler 576 uses a filler different from the second filler 578 shown below, and has better radiation (X-ray) transmittance than the second filler 578. Is used.

  On the other hand, a space B surrounded by the outer surface of the protective member 523 and the protective member 572 is filled with a second filler 578 as an elastic filler having elasticity.

  As the second filler 578, a filler having an elongation at break of 120% or more and 500% or less is used. Specifically, as the second filler 578, for example, a silicone resin or a modified silicone adhesive is used. Used. Examples of the modified silicone adhesive include Cemedine Super X (registered trademark (manufactured by Cemedine Co., Ltd.)), TSE392 (manufactured by Momentive Performance Materials Japan GK), MOS-7 (registered trademark (manufactured by Konishi Co., Ltd.)). )) 1200 series (manufactured by ThreeBond Co., Ltd.) can be used.

  JIS K 6251 is used as a method for measuring elongation at break.

  Further, in the radiation detection substrate 500, the second filler 578 is a filler different from the first filler 576, and has a higher elongation at break and faster drying than the first filler 576. It has been.

  In addition, when a conductive paste is used for the conductive member 580, the second filler 578 is selected so that the conductive paste does not melt and diffuse into the second filler 578. The second filler 578 is selected so that the insulation performance does not deteriorate significantly due to moisture absorption.

  Further, in the space B, as shown in FIG. 15, an insulating member 582 made of a film material such as polyethylene terephthalate (PET) is covered on the upper surface of the second filler 578, and the dielectric breakdown upwards Is suppressed.

  Note that the members and materials used in the optical reading type radiation detector can be applied to corresponding parts having the same function in the TFT type radiation detector. The present invention is not limited to the above-described embodiment, and various modifications, changes, and improvements can be made.

FIG. 1 is a schematic cross-sectional view showing the overall configuration of a TFT radiation detector. FIG. 2 is a schematic configuration diagram showing a main part of a TFT radiation detector. FIG. 3 is a cross-sectional view showing the structure of one pixel unit of a TFT radiation detector. FIG. 4 is a plan view showing the structure of one pixel unit of a TFT radiation detector. FIG. 5 is a schematic plan view showing a connection portion where the extension electrode portion and the high voltage line are connected in the TFT type radiation detector. FIG. 6 is a schematic side view showing a connection portion where the extension electrode portion and the high voltage line are connected in the TFT type radiation detector. FIG. 7 is a schematic cross-sectional view showing a case where the extension electrode portion is extended at the same height as the bias electrode in the TFT radiation detector. FIG. 8 is a diagram showing a schematic configuration of a radiation detection substrate as an optical reading type radiation detector. FIG. 9 is a diagram showing a schematic structure of the radiation detection lower substrate of the radiation detection substrate shown in FIG. FIG. 10 is a schematic view schematically showing the configuration of the radiation detection substrate shown in FIG. FIG. 11 is a diagram showing a sealing structure for sealing the upper electrode of the radiation detection substrate shown in FIG. FIG. 12 is a block diagram showing a configuration of the charge extraction amplifier and a connection mode between the charge extraction amplifier and an image processing apparatus disposed outside the radiation detection substrate. FIG. 13 is a schematic diagram showing a state when line light is scanned as reading light. FIG. 14 is a schematic side view showing a connection portion where the extension electrode portion and the high voltage line are connected in the radiation detection substrate shown in FIG. 8. FIG. 15 is a schematic cross-sectional view showing a case where the extension electrode portion is extended at the same height as the bias electrode in the radiation detection substrate shown in FIG.

Explanation of symbols

400 radiation detector
401 Bias electrode (upper electrode)
404 Photoconductive layer (charge conversion layer)
407a Charge collection electrode (lower electrode)
408 Glass substrate (substrate)
431 Extension electrode
432 High voltage wire (electric wire)
444 1st filler
445 Second filler
500 Radiation detection board (radiation detector)
518 Upper electrode (upper electrode part)
519 Extension electrode
522 Radiation detection layer (charge conversion layer)
520 Lower electrode (lower electrode part)
524 Lower substrate for radiation detection (substrate)
514 High voltage wire (electric wire)
576 1st filler
578 Second filler

Claims (1)

A charge conversion layer that generates a charge upon incidence of radiation; and
A lower electrode part provided under the charge conversion layer and collecting charges generated by the charge conversion layer;
A substrate on which the lower electrode portion is provided;
An upper electrode part formed on the charge conversion layer for applying a bias voltage to the charge conversion layer;
An extended electrode portion extended from the upper electrode portion outside a detectable region where the lower electrode portion can collect radiation by collecting charges;
An electric wire connected to the extension electrode part outside the detectable region and for applying a bias voltage from the extension electrode part to the charge conversion layer via the upper electrode part;
A first filler filled in the detectable region and composed of an element having an atomic number of 9 or less;
A second filler having an elasticity filled in a connecting portion to which the extension electrode portion and the electric wire are connected;
A radiation detector comprising:

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