JP2009158510A - Radiographic image detecting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a radiographic image detecting device which reduces its leakage current, suppresses crystallization caused at an edge of a contact hole, and stabilizes its electric field. <P>SOLUTION: The radiographic image detecting device having, a substrate 1, a stack of a charge generating layer 6 which is exposed to radiation to generate electric charges, a voltage application electrode 7 for applying a voltage to the charge generating layer 6, a charge collecting electrode 11 for collecting the electric charges generated by the charge generating layer 6, and a detecting layer 10 having a two-dimensional array of many pixel portions each having a switching element for reading electric charges collected by the charge collecting element 11, is provided with an electric field relaxing member 17 only in a contact hole 16 in a plane of the charge collecting electrode 11 and in a peripheral region of the contact hole 16. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a radiation image detection apparatus that generates electric charges upon irradiation of radiation, and more particularly to a configuration of a drive circuit board of the radiation image detection apparatus.

  In recent years, flat panel detectors (FPDs) have been put into practical use in which an X-ray sensitive layer is disposed on a TFT (Thin Film Transistor) active matrix array and X-ray information can be directly converted into digital data. Compared to the conventional imaging plate, there is an advantage that an image can be confirmed immediately and a moving image can be confirmed, and it is rapidly spreading. In such a radiation image detection apparatus called FPD, since an image signal can be directly detected, there is an advantage that an accurate image can be detected.

  In this direct conversion type radiation image detection apparatus, it is necessary to dispose a charge collection electrode between the charge generation layer and the interlayer insulating film. This charge collection electrode collects the charge generated in the charge generation layer and stores the signal between the storage capacitor upper electrode and the storage capacitor lower electrode under the interlayer insulation film through the contact hole provided in the interlayer insulation film. is there. Therefore, it is necessary to form a contact hole at least for each pixel.

  However, when, for example, amorphous selenium (a-Se) is deposited as a charge generation layer on a contact hole formed, the deposited Se layer is deposited at the lower concavo-convex portion, particularly at the edge of the contact hole. Crystallization tends to proceed starting from internal stress during deposition. When such crystallization occurs, a Se leak current is generated in a specific pixel, resulting in an increase in the leak current, which affects the data of other pixels and makes it difficult to recognize a detection signal that should be detected originally. Become. Therefore, a flattening film made of an organic material for flattening the deposition surface of the charge generation layer is disposed under the charge generation layer (for example, Patent Document 1).

On the other hand, there is also known a radiation image detection device of a type that stores between a lower storage capacitor upper electrode and a storage capacitor upper electrode from a charge collection electrode that collects charges generated in the charge generation layer without providing a contact hole (patent) Reference 2).
JP 2006-156555 A Japanese Patent Laid-Open No. 5-167056

  In the case of the radiation image detection apparatus of Patent Document 2, there is a known problem that electric field concentration occurs at the end of the pixel electrode. On the other hand, when a contact hole is provided as in Patent Document 1, there is a known problem of electric field concentration in the contact hole and its periphery. As a countermeasure, it is disclosed that the entire surface of the charge collection electrode including the contact hole is covered with an organic film and flattened. However, even in an embodiment in which a conductive material is added to the organic film, the electric resistance is an electrode. Since it is higher than the material, there is a problem that the running of electric charge is worsened.

  In particular, the above radiation image detection apparatus has a property that charges generated by radiation tend to accumulate because there are no electrodes in the space region between the charge collection electrodes provided separately. As a result, a phenomenon occurs in which the lines of electric force are distorted, the effective sensitive area changes, and the sensitivity varies. In addition, there is a problem that even after the radiation incidence is stopped, the charge accumulated in the region of the space between the charge collecting electrodes is gradually swept out and an afterimage is generated. Further, when radiation having a higher rate than the charge sweeping rate is incident, charges accumulate in the region where the charge collection electrode is formed, the potential profile in the semiconductor is distorted, and the potential near the charge collection electrode rises. In particular, since the above-described radiological image detection apparatus needs to be used with a high bias applied to a-Se, the potential increase in the vicinity of the charge collection electrode becomes large enough to affect the switching operation of the TFT. As a result, a phenomenon such as a slow reading operation occurs, which causes sensitivity fluctuations and afterimages.

  In order to solve such problems, the radiation image detection device is provided with a light irradiation mechanism that emits light during radiation detection, and the electric field generated in the radiation image detection device equipped with the charge collection electrode is stabilized by light irradiation. In addition, there is also known a radiological image detection apparatus having no sensitivity fluctuation. However, in such an apparatus, if the entire surface of the charge collection electrode is covered as described in Patent Document 1, light irradiation cannot be performed sufficiently. The electric field cannot be stabilized. In particular, when a powder such as carbon is added to the organic film in order to lower the resistance as in Patent Document 1, the original significance of the radiation image detection apparatus provided with the light irradiation mechanism is lost.

The present invention has been made in view of the above circumstances, and it is possible to reduce the leakage current caused by the contact hole, and to suppress crystallization that occurs at the edge of the contact hole. An object of the present invention is to provide a radiological image detection apparatus capable of stabilizing an electric field even in a radiographic image detection apparatus provided with a light irradiation mechanism for irradiating light.

  The radiological image detection apparatus of the present invention has, as a first aspect, at least a charge generation layer that generates a charge upon irradiation with radiation, a voltage application electrode for applying a voltage to the charge generation layer, and the charge A charge collection electrode that collects the charges generated in the generation layer, and a detection layer in which a plurality of pixel portions each having a switching element for reading the charge collected by the charge collection electrode are arranged in a two-dimensional manner are formed on the substrate. In the laminated radiographic image detection apparatus, a contact hole is provided in the surface of the charge collection electrode, and an electric field relaxation member is provided only in the contact hole and a peripheral region of the contact hole.

  The radiological image detection apparatus according to the present invention includes, as a second aspect, at least a charge generation layer that generates a charge upon irradiation with radiation, a voltage application electrode for applying a voltage to the charge generation layer, and the charge A charge collection electrode that collects the charges generated in the generation layer, and a detection layer in which a plurality of pixel portions each having a switching element for reading the charge collected by the charge collection electrode are arranged in a two-dimensional manner are formed on the substrate. In the stacked radiation image detection apparatus, the electric field reducing member has a contact hole in a plane of the charge collecting electrode, and the electric field reducing member is provided only in the contact hole, a peripheral region of the contact hole, and a peripheral region of the outer peripheral end of the charge collecting electrode Is provided.

  In the radiological image detection apparatus according to the second aspect, the electric field relaxation member provided in a peripheral region of the outer peripheral end of the charge collection electrode is provided integrally so as to cover the ends of the adjacent charge collection electrodes. In such a case, the electric field relaxation member is made of an insulating material.

  In the radiological image detection apparatus according to the second aspect, the electric field relaxation member provided in the peripheral region of the outer peripheral end of the charge collection electrode is connected between one end and the other end of the adjacent charge collection electrode. They may be provided apart from each other.

  It is preferable that the radiographic image detection apparatus of said 1st aspect and 2nd aspect is equipped with the light irradiation mechanism which irradiates light at least during the detection of a radiation.

  The radiological image detection apparatus according to the first aspect of the present invention has a contact hole in the plane of the charge collection electrode, and an electric field relaxation member is provided only in the contact hole and a peripheral region of the contact hole. In the radiographic image detection apparatus of the second aspect, since the electric field relaxation member is provided only in the contact hole, the peripheral area of the contact hole, and the peripheral area of the outer peripheral edge of the charge collection electrode, the radiation image detection apparatus covers the entire surface of the charge collection electrode. Compared with this, there is no problem that the charge travels worse, leakage current due to the contact hole can be reduced, and crystallization occurring at the edge of the contact hole can be suppressed.

  The radiation image detection apparatus of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic cross-sectional view showing the structure of a pixel unit of a radiological image detection apparatus showing one embodiment of the present invention.

  As shown in FIG. 1, the radiation image detection apparatus of the present invention is an active matrix substrate that is a detection layer in which a large number of pixel portions having switching elements for reading out the charges collected by the charge collection electrodes are two-dimensionally arranged. A charge generation layer (photoelectric conversion layer) 6 having electromagnetic conductivity and a voltage application electrode (bias electrode: common electrode) 7 connected to a high voltage power source (not shown) are sequentially formed on the substrate 10. The charge generation layer 6 generates charges (electrons-holes) inside when irradiated with electromagnetic waves such as X-rays. That is, the charge generation layer 6 has electromagnetic wave conductivity and is for converting image information by X-rays into charge information. The charge generation layer 6 is made of, for example, a-Se containing selenium as a main component. Here, the main component means a content of 50% or more.

  The active matrix substrate 10 includes a glass substrate 1, a gate electrode 2, a storage capacitor lower electrode 14, a gate insulating film 15, a storage capacitor upper electrode 13, a semiconductor layer 9, a source electrode 8, a drain electrode 5, an interlayer insulating film 12, and a charge collection. A thin film transistor (TFT: Thin Film Transistor; hereinafter referred to as TFT switch) 4 is configured by the gate electrode 2, the gate insulating film 15, the source electrode 8, the drain electrode 5, the semiconductor layer 9, and the like. ing. The TFT switch 4 is a switching element, and the source electrode 8 and the drain electrode 5 are connected to a data wiring (not shown) that is an electrode wiring arranged in a lattice pattern and a storage capacitor upper electrode 13. The semiconductor layer 9 is intended to contact the source electrode 8, the drain electrode 5 and the gate electrode 2.

The glass substrate 1 is a support substrate. As the glass substrate 1, for example, a non-alkali glass substrate can be used. The gate insulating film 15 is made of SiN _X or SiO _X like. The gate insulating film 15 is provided so as to cover the gate electrode 2 and the storage capacitor lower electrode 14, and a portion located on the gate electrode 2 acts as a gate insulating film in the TFT switch 4, and The region located at acts as a dielectric layer in the charge storage capacitor. That is, the charge storage capacitor is formed by the overlapping region of the storage capacitor lower electrode 14 and the storage capacitor upper electrode 13 formed in the same layer as the gate electrode 2. The gate insulating film 15 is not limited to SiN _x or SiO _x , but can be used in combination with an anodized film obtained by anodizing the gate electrode 2 and the storage capacitor lower electrode 14.

  On the glass substrate 1, a gate electrode 2 and a storage capacitor lower electrode 14 are provided. A semiconductor layer 9 is formed above the gate electrode 2 via a gate insulating film 15, and a source electrode 8 and a drain electrode 5 are further formed thereon. A gate insulating film 15 is disposed above the storage capacitor lower electrode 14, and a storage capacitor upper electrode 13 is disposed above the gate insulating film 15.

  The interlayer insulating film 12 is made of, for example, an acrylic resin having photosensitivity, and serves to electrically isolate the TFT switch 4. A contact hole 16 passes through the interlayer insulating film 12, and the charge collection electrode 11 is connected to the storage capacitor upper electrode 13. That is, the charge collection electrode 11 is connected to the storage capacitor upper electrode 13 which is a signal extraction electrode through the contact hole 16.

  The charge collection electrode 11 is made of, for example, an amorphous transparent conductive oxide film, and the charge collection electrode 11 is a contact located on a portion of the storage capacitor upper electrode 13 facing the storage capacitor lower electrode 14 via the charge storage capacitor. The hole 16 is formed so as to be filled, and is stacked on the source electrode 8, the drain electrode 5, and the storage capacitor upper electrode 13. The charge collection electrode 11 and the charge generation layer 6 are electrically connected, and the charge generated in the charge generation layer 6 can be collected by the charge collection electrode 11. Further, since the charge collection electrode 11 needs to collect charges generated in the charge generation layer 6 and output them to the outside via the TFT and data wiring (not shown), the charge collection electrode 11 passes through the contact hole 16 formed in the interlayer insulating film 12. The TFT switch 4 is electrically connected to the drain electrode 5 and the charge storage capacitor. The charge generation layer 6 is formed immediately above the charge collection electrode 11 because it is necessary to transfer the charge to the charge collection electrode 11.

  An electric field relaxation member 17 is provided in the contact hole 16 and in a peripheral region of the contact hole 16 so as to bury the contact hole 16. Here, the peripheral region of the contact hole 16 (region indicated by P in FIG. 1) means a region 5 μm from the end (edge) of the contact hole, preferably 3 μm, and more preferably 2 μm. . The electric field relaxation member 17 is preferably provided with a curvature that relaxes the edge of the contact hole 16.

As a constituent material of the electric field relaxation member 17, an organic resin having a low coefficient of thermal expansion that is approximately the same as the material of the charge generation layer 6 can be preferably used, and preferably a novolac resin, an epoxy resin, or an acrylic resin. Photosensitive resins such as urethane resin, polyester resin, polyimide resin, and polyolefin resin are preferable. In addition, a material in which a charge transporting material / conductive material is dispersed in a charge transporting polymer film or an insulating resin can be preferably used. Further, since the electric field relaxation member 17 shown in FIG. 1 does not cover the entire charge collecting electrode 11, SiO ₂ , TiO ₂ , CeO ₂ , GeO ₂ , Al ₂ O ₃ , Ta ₂ O ₅ , WO ₃ , MoO ₃ , MgO, PbO, BeO, V ₂ O ₅ , NiO, Co ₂ O ₃ , SiC, Si ₃ N ₄ , As ₂ Se _3, etc., with a specific resistance equal to or higher than that of the charge generation layer An insulating material can also be used.

  A high voltage power supply (not shown) is connected between the bias electrode 7 and the storage capacitor lower electrode 14. A voltage is applied between the bias electrode 7 and the storage capacitor lower electrode 14 by the high voltage power source. As a result, an electric field can be generated between the bias electrode 7 and the charge collection electrode 11 via the charge storage capacitor. At this time, since the charge generation layer 6 and the charge storage capacitor are electrically connected in series, if a bias voltage is applied to the bias electrode 7, charge ( Electron-hole pairs) are generated. The electrons generated in the charge generation layer 6 move to the + electrode side, and the holes move to the − electrode side. As a result, charges are stored in the charge storage capacitor.

  As a whole radiological image detection apparatus, a plurality of charge collection electrodes 11 are two-dimensionally arranged, a charge storage capacitor individually connected to the charge collection electrode 11, and a TFT switch 4 individually connected to the charge storage capacitor, There are multiple. Thus, two-dimensional electromagnetic wave information is temporarily stored in the charge storage capacitor, and the TFT switch 4 is sequentially scanned, whereby the two-dimensional charge information can be easily read out.

  FIG. 2 is a schematic cross-sectional view showing the structure of a pixel unit of a radiological image detection apparatus showing another aspect of the present invention. In FIG. 2, the same components as those in FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted unless necessary (the same applies hereinafter). In the radiological image detection apparatus shown in FIG. 2, the electric field relaxation member 17 is provided only in the contact hole 16, the peripheral region of the contact hole 16, and the peripheral edge portion peripheral region of the charge collection electrode 11. The electric field relaxation member 17 provided in the peripheral region is integrally provided so as to cover the ends of the adjacent charge collection electrodes 11. Here, the peripheral region around the outer peripheral edge of the charge collection electrode 11 (region indicated by Q in FIG. 2) means a region 5 μm from the end of the charge collection electrode 11, preferably 3 μm, and more preferably 2 μm. Is preferred. The electric field relaxation member 17 is preferably provided with a curvature that does not cause a new step.

  In the radiological image detection apparatus shown in FIG. 2, the electric field relaxation member 17 provided in the contact hole 16 and in the peripheral region of the contact hole 16 can be the same as that described in FIG. As for the electric field relaxation member 17 that is integrally provided so as to cover the ends of the charge collection electrodes 11 to be electrically connected, the pixels are not separated when the adjacent charge collection electrodes are electrically connected. 17 is comprised by said insulating material.

  FIG. 3 is a schematic cross-sectional view showing the structure of a pixel unit of a radiological image detection apparatus showing still another aspect of the present invention. In the radiological image detection apparatus shown in FIG. 3, the electric field relaxation member 17 is provided only in the contact hole 16, the peripheral region of the contact hole 16, and the peripheral edge portion peripheral region of the charge collection electrode 11, and provided only in the peripheral edge peripheral region. The electric field relaxation member 17 is provided so as to be separated between one end and the other end of the adjacent charge collection electrode 11. Here, the peripheral region around the outer peripheral edge of the charge collecting electrode 11 (the region indicated by Q in FIG. 3) means a region 5 μm from the end of the charge collecting electrode 11, preferably 3 μm, as in the case shown in FIG. Furthermore, it is preferable that it is 2 micrometers. The electric field relaxation member 17 is preferably provided with a curvature that relaxes the step at the end of the charge collection electrode 11. In the radiological image detection apparatus shown in FIG. 3, the electric field relaxation member 17 is provided in the contact hole 16 so as to be separated from one end and the other end of the contact hole 16 and the adjacent charge collection electrode 11. Can be the same as those described in FIG.

  FIG. 4 is a schematic cross-sectional view of a radiation image detection apparatus provided with a light irradiation mechanism. This radiographic image detection device includes a light irradiation mechanism 20 that irradiates light at least during detection of radiation on the back surface of the active matrix substrate 10 on the glass substrate 1 side. The light irradiation mechanism 20 is, for example, a backlight having a green light emitting diode having a peak emission wavelength of about 570 nm or the like mounted on the inside thereof, and is attached to the glass substrate 1 with a transparent adhesive. The light irradiation mechanism 20 can uniformly irradiate light on the charge collection electrode 11 side of the charge generation layer 6 through the active matrix substrate 10. The light irradiation by the light irradiation mechanism 20 is preferably continued at least while the electric charge is read out as an electric signal. However, the light irradiation mechanism 20 is not limited to this. For example, the light irradiation mechanism 20 may be irradiated after the end of the detection operation. You may be made to irradiate.

  In order to irradiate the charge generation layer 6 with more light, slit holes may be formed in the storage capacitor upper electrode 13 and the storage capacitor lower electrode 14.

  In the radiation image detection apparatus provided with the light irradiation mechanism 20, by applying light from the light irradiation mechanism 20, one of charges generated by light (a positive bias is applied to the bias electrode 7) even in a state before radiation incidence. Holes in this case) are already present in the space region between the charge collection electrodes 11 adjacent to each other (the upper region of the electric field relaxation member 17 provided integrally so as to cover the ends of the adjacent charge collection electrodes 11). Accumulated. Even if the light transmittance of the electrolytic relaxation member 17 is low, the influence is small because the electrolytic relaxation member 17 is a small region. Even if radiation is incident in this state, of the charges (electrons / holes) generated in the space region between the charge collection electrodes 11, the charges moving to the charge collection electrode 11 (holes in this case) The charge collection electrode 11 is reached along the line of force, and no further charge is accumulated in the space region between the charge collection electrodes 11, so that the state of the electric line of force does not change and the sensitivity fluctuation does not occur. Is possible.

  In the radiological image detection apparatus provided with the light irradiation mechanism 20, if the entire surface of the charge collection electrode 11 is covered with the electric field relaxation member 17, even if light is irradiated from the light irradiation mechanism 20, light is sufficiently irradiated. Inability to stabilize the electric field, it is difficult to suppress fluctuations in sensitivity.

Subsequently, a manufacturing process of the radiological image detection apparatus will be described.
First, a metal film such as Ta or Al is formed on the glass substrate 1 by sputtering deposition, and then patterned into a desired shape, thereby forming the gate electrode 2 and the storage capacitor lower electrode 14. Then, a gate insulating film 15 made of SiN _x , SiO _x or the like is formed on the substantially entire surface of the glass substrate 1 by the CVD method so as to cover the gate electrode 2 and the storage capacitor lower electrode 14.

  Next, a-Si is formed by a CVD method so that the semiconductor layer 9 is disposed above the gate electrode 2 through the gate insulating film 15, and then patterned into a desired shape. 9 is formed. After a metal film such as Ta or Al is formed on the semiconductor layer 9 by sputtering deposition, the source electrode 8 and the drain electrode 5 are formed by patterning into a desired shape. Further, the storage capacitor upper electrode 13 is formed on the storage capacitor lower electrode 14, and the data wiring is formed at a predetermined position.

  In this way, a photosensitive acrylic resin or the like is formed so as to cover substantially the entire surface of the glass substrate 1 on which the TFT switch 4 and the charge storage capacitor are formed, and the interlayer insulating film 12 is formed. The interlayer insulating film 12 is aligned with the portion to be the contact hole 16 to fix the photomask, photolithography (exposure) is performed, and then contact hole patterning is performed by etching with an organic solvent. 16 is formed.

  After the contact hole 16 is formed, an amorphous transparent conductive oxide film such as ITO (Indium-Tin-Oxide) is formed on the interlayer insulating film 12 by a sputter deposition method, and patterned into a desired shape to collect the charge collecting electrode. 11 is formed. At this time, the charge collection electrode 11 and the storage capacitor upper electrode are electrically connected (short-circuited) through the contact hole 16 provided in the interlayer insulating film 12. Since the charge collection electrode 11 is formed by vapor deposition, it can be formed while maintaining the shape of the formed contact hole.

  Subsequently, the electric field relaxation member 17 is provided. When the electric field relaxation member 17 is an organic film, it can be formed by inkjet method (IJ) or slit coating. In addition, as shown in FIG. 3, when the electric field relaxation member 17 is separated between one end and the other end of the adjacent charge collection electrode 11, for example, by using a photosensitive resin. It can be formed by performing desired patterning with a mask by photolithography.

When the electric field relaxation member 17 is made of SiO ₂ or the like, it can be provided at a predetermined position by a CVD method or a sputtering method. In addition, when the electric field relaxation member 17 as shown in FIG. 3 is separated between one end portion and the other end portion of the adjacent charge collection electrode 11, the electric field relaxation member 17 is first disposed adjacently. Are formed integrally so as to cover the end portions of the charge collecting electrode 11 to be covered, and then a resist pattern that covers only the peripheral portion of the charge collecting electrode 11 is formed, and other portions are made anisotropic or isotropic. Etching is performed until the interlayer insulating film 12 is exposed to form the electric field relaxation member 17 having the above shape.

  A charge generation layer 6 made of a-Se and having electromagnetic conductivity is formed by vacuum deposition so as to cover the entire pixel array region of the active matrix substrate 10 formed as described above. Finally, a bias electrode 7 made of Au, Al or the like is formed on substantially the entire surface of the charge generation layer 6 by a vacuum deposition method.

It should be noted that a charge injection blocking layer that blocks injection of electrons or holes into the charge generation layer 6 at the interface between the charge generation layer 6 and the charge collection electrode 11, and adhesion between the charge generation layer 6 and the charge collection electrode 11. You may form the buffer layer which improves this. Similarly, a charge injection blocking layer or a buffer layer may be formed at the interface between the charge generation layer 6 and the bias electrode 7. As the charge injection blocking layer and the buffer layer, a-As ₂ Se ₃ , a-Se to which alkali element ions or halogen element ions are added, or the like can be used.
Examples are shown below.

Example 1
A photosensitive acrylic resin film is formed to a thickness of about 3 μm on a substrate on which switching TFTs and storage capacitors are arranged to form an interlayer insulating film, and the interlayer insulating film is aligned with a portion to be a contact hole. The photomask was fixed and photolithography was performed, followed by etching with an organic solvent to pattern the contact hole to form a contact hole having a depth of 4 μm. Next, ITO is formed on the interlayer insulating film to a thickness of about 200 nm by sputtering deposition, and patterned under the conditions of a pixel size of 150 × 150 μm and a charge collection electrode of 120 × 120 μm (fill factor of 64%). Formed.

A photosensitive resin made of a novolac resin was applied on the charge collection electrode having the contact hole, and was patterned by photolithography so that the resin remained only in the contact hole and the peripheral region of the contact hole. Thereafter, baking was performed at 220 ° C. for 1 hour to provide an arc-shaped electric field relaxation member. Next, antimony sulfide Sb ₂ S ₃ was formed to a thickness of 2 μm as a charge transport layer, and an a-Se layer was formed as a charge generation layer to a thickness of 1000 μm. Subsequently, antimony sulfide Sb ₂ S ₃ was formed to a thickness of 0.6 μm as a charge transport layer. Finally, an upper electrode Au (0.1 μm) was formed to produce a radiation image detection device.

(Example 2)
In Example 1, the position where the electric field relaxation member is provided is added in the contact hole and the peripheral region of the contact hole, and is integrally provided so as to cover the ends of the adjacent charge collecting electrodes as shown in FIG. Produced a radiographic image detection apparatus in the same manner as in Example 1.

(Comparative Example 1)
Example 2 is different from Example 2 except that the electric field relaxation member is not provided in the contact hole and the peripheral region of the contact hole, and only the part provided integrally so as to cover the ends of the charge collection electrodes is left. Similarly, a radiation image detection apparatus was produced.

(Comparative Example 2)
In Example 1, a radiological image detection apparatus was produced in the same manner as in Example 1 except that the electric field relaxation member was provided on the entire surface of the charge collection electrode.

(Evaluation)
The X-ray sensitivity and the number of image defects after aging at 40 ° C. to 300 hours were measured. X-ray sensitivity was measured by applying a voltage of −10 kV and irradiating with 28 keV X-rays after 5 minutes to measure the X-ray sensitivity and defects. The number of image defects was obtained from an offset image after 60 s by applying a voltage of −2 kV.

The afterimage was evaluated as follows. Irradiate pulse X-rays with a tube voltage of 80 kV, tube current of 100 mA, and 710 ms (the dose at the substrate is 400 mR), apply +10 kV to the voltage application electrode, connect the readout side to an IV amplifier, and use the oscilloscope Change was acquired. The current value 15 seconds after the end of the pulse was converted into a dose and used as the afterimage value. Since this afterimage value is preferably 0.12 mR or less, more preferably 0.012 mR or less, the evaluation is ○ when the value is 0.012 mR or less, and Δ when the value is greater than 0.012 mR and 0.12 mR or less. The case where it was larger than 0.12 mR was evaluated as x.
The measurement results are shown in Table 1. In addition, the numerical value of a table | surface is shown by the relative value which set the measured value of Example 2 to 1.

  From the comparison of Comparative Example 1 and Examples 1 and 2 in Table 1, it can be seen that the contact hole and the electric field relaxation member around it are effective in suppressing image defects. In addition, pixel defects can be further suppressed by relaxing the electric field at the end of the charge collection electrode. On the other hand, the comparison with Comparative Example 2 shows that the afterimage suppression effect is reduced when the resin layer is formed on the entire surface. In view of the above, an electric field relaxation member is provided at least in the contact hole and its peripheral region (Example 1), or in both the contact hole and its peripheral region and the peripheral region of the outer periphery of the charge collection electrode (Example 2). As a result, it is possible to reduce the leakage current caused by the contact hole and suppress image defects, and to suppress afterimages.

1 is a schematic cross-sectional view showing a structure of a pixel unit of a radiological image detection apparatus showing one embodiment of the present invention The schematic sectional drawing which shows the structure of the pixel unit of the radiographic image detection apparatus which shows another aspect of this invention The schematic sectional drawing which shows the structure of the pixel unit of the radiographic image detection apparatus which shows another aspect of this invention Schematic cross-sectional view of a radiation image detection apparatus equipped with a light irradiation mechanism

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Glass substrate 2 Gate electrode 3 Data wiring 4 TFT switch 5 Drain electrode 6 Charge generation layer 7 Bias electrode 8 Source electrode 9 Semiconductor layer 10 Active matrix substrate 11 Charge collection electrode 12 Interlayer insulating film 13 Storage capacity upper electrode 14 Storage capacity lower electrode 15 Gate insulating film 16 Contact hole 17 Electric field relaxation member 20 Light irradiation mechanism

Claims (5)

At least a charge generation layer that generates a charge upon irradiation with radiation, a voltage application electrode for applying a voltage to the charge generation layer, a charge collection electrode that collects the charge generated in the charge generation layer, and In the radiological image detection apparatus in which a detection layer in which a large number of pixel portions having switching elements for reading out the charges collected by the charge collection electrode are two-dimensionally arranged is stacked on a substrate,
A radiological image detection apparatus comprising a contact hole in a plane of the charge collection electrode, and an electric field relaxation member provided only in the contact hole and a peripheral region of the contact hole. At least a charge generation layer that generates a charge upon irradiation with radiation, a voltage application electrode for applying a voltage to the charge generation layer, a charge collection electrode that collects the charge generated in the charge generation layer, and In the radiological image detection apparatus in which a detection layer in which a large number of pixel portions having switching elements for reading out the charges collected by the charge collection electrode are two-dimensionally arranged is stacked on a substrate,
A contact hole is provided in a plane of the charge collection electrode, and the electric field relaxation member is provided only in the contact hole, a peripheral region of the contact hole, and an outer peripheral end peripheral region of the charge collection electrode. Item 2. The radiological image detection apparatus according to Item 1.   The electric field relaxation member provided in the peripheral region of the outer peripheral edge of the charge collection electrode is integrally provided so as to cover the ends of the adjacent charge collection electrodes, and the electric field relaxation member is made of an insulating material. The radiological image detection apparatus according to claim 2.   The electric field relaxation member provided in the peripheral region of the outer peripheral end of the charge collection electrode is provided so as to be separated between one end and the other end of the adjacent charge collection electrode. The radiation image detection apparatus according to claim 2.   The radiation image detection apparatus according to claim 1, further comprising a light irradiation mechanism that emits light during detection of radiation.

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