JP2004226313A - Radiation detector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve problems with a method of directly connecting an aluminum reflecting layer with an external GND in which the structure and the manufacturing process thereof becomes complicated, a risk of peeling of the reflecting layer exists, and sealing is difficult due to the structure. <P>SOLUTION: A wire connecting part 3-e is formed on a substrate 1. When a reflecting layer 9 is formed on a phosphor 7 by deposition, the wire connecting part 3-e is connected with the reflecting layer by deposition at the same time. In addition, the wire connecting part 3-e is connected to a constant electric potential through a constant potential wiring 3-d. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a radiation detection device used for a medical diagnostic device, a nondestructive inspection device, and the like, and a method for manufacturing the same.
[0002]
[Prior art]
In recent years, digitization of radiography has been accelerated, and X-ray area sensors have been announced by various companies. There are two methods: direct method (type that converts X-rays directly into electric signals and reads) and indirect method (type that converts X-rays into visible light and converts visible light into electric signals and reads). It is roughly divided.
[0003]
FIG. 12 is a sectional view showing a radiation detecting element disclosed in WO98 / 36290. In FIG. 12, 100 indicates a photoelectric conversion panel, and 300 indicates a scintillator unit. A plurality of photoelectric conversion elements 2 are formed on a substrate 1 constituting the photoelectric conversion panel 100, and a protective layer 5 is formed thereon. The wiring 3 extending from the photoelectric conversion element 2 is connected to the bonding pad portion 4. The columnar phosphor 7 of the scintillator unit 300 is formed on the protective layer 5. The phosphor 7 is separated from the outside by a protective layer 8 made of parylene, a reflective layer 9 made of aluminum, and a protective layer 10 made of parylene. Is protected from moisture.
[0004]
The reflective layer 9 made of aluminum is provided to reflect light traveling from the phosphor 7 to the side opposite to the photoelectric conversion unit and to guide the light to the photoelectric conversion unit. Reference numeral 15 denotes a coating resin for preventing the protective layer 8 from peeling off. The X-rays incident from the upper part of the drawing pass through the protective layer 8, the reflective layer 9, and the protective layer 10 and are absorbed by the phosphor 7, and the emitted light reaches the photoelectric conversion element 2 and passes through the wiring 3 to the outside (not shown). By reading out the data by a circuit, the incident X-ray information is converted into a two-dimensional digital image.
[0005]
[Problems to be solved by the invention]
In the radiation detecting apparatus using such a radiation detecting element, since the aluminum of the reflective layer 9 is electrically floating as is clear from FIG. 12, the potential becomes unstable due to the influence of external noise and static electricity, and This affects the reading mechanism of the photoelectric conversion element and disturbs the image. Since the reflection layer 9 is closest to the photoelectric conversion element 2, the influence is large.
[0006]
This effect will be described with reference to an example in which a MIS sensor 501 and a TFT (thin film transistor) 502 are used as photoelectric conversion elements. FIG. 13 is a schematic sectional view thereof. 13, the same parts as those in FIG. 12 are denoted by the same reference numerals. First, the potential of the lower electrode 201-b slightly changes due to carriers generated by light incident on the active layer 203-b of the MIS sensor unit 501. The drain electrode 30-b connected to the lower electrode 201-b also changes at the same time.
[0007]
This small potential difference is sent out to the signal line 30-a by switching by the TFT 502, and the reading is completed. At this time, if the potential of the reflective layer 9 becomes unstable due to the influence of external magnetic field noise or internal static electricity, the drain electrode 30-b and the signal line 30-a also become unstable, as schematically shown in FIG. , Causing electrical fluctuations. This can lead to catastrophic image distortions and, in particular, misdiagnosis that should not be in the medical field.
[0008]
As a countermeasure, a method of connecting such an aluminum reflective layer 9 directly to an external GND has already been proposed. However, this method not only complicates the structure and the manufacturing process, but also makes the reflective film in the manufacturing process complicated. In this case, there is a danger that the reflective layer will be peeled off when the protective layer is peeled off, and it is difficult to seal the periphery.
[0009]
An object of the present invention is to provide a simple and easy-to-manufacture structure for stabilizing the potential of a conductive layer located close to a photoelectric conversion element, and at the same time, to simplify surrounding sealing, to reduce external noise and static electricity at low cost. An object of the present invention is to provide a strong radiation detection device and a method for manufacturing the same.
[0010]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides a radiation detection device in which a wavelength converter and a conductor layer are arranged on a photoelectric conversion panel on which a photoelectric conversion element is formed, wherein the conductor layer is a constant potential wiring of the photoelectric conversion panel. And is connected to a constant potential through
[0011]
In the present invention, in the circuit of the photoelectric conversion panel, a constant potential wiring for connecting to the conductor layer is provided, and the constant potential wiring is fixed to a constant potential by an electric mounting component;
The connection portion between the constant potential wiring and the conductive layer is located at a position other than the bonding pad portion and the photoelectric conversion element area provided around the photoelectric conversion panel,
The connection portion between the constant potential wiring and the conductive layer is arranged symmetrically in a well-balanced manner throughout the photoelectric conversion panel,
The conductor layer is a reflective layer that reflects light of the wavelength converter,
The conductor layer is in contact with the constant potential wiring by vapor deposition,
The conductive layer is connected to a constant potential wiring by a conductive resin,
Sealing the periphery of the photoelectric conversion panel,
Is preferably contained.
[0012]
Also, the present invention provides a photoelectric conversion element on a substrate, a bonding pad portion connected to the outside, a wiring connection portion, a step of forming a constant potential wiring for connecting the wiring connection portion to a constant potential through the bonding pad portion, Forming a protective layer, removing the protective layers of the bonding pad portion and the wiring connection portion, forming a phosphor layer on the photoelectric conversion element, and forming a conductor layer on the phosphor layer And a step of connecting the conductor layer and the wiring connection portion.
[0013]
Further, in the present invention, the method includes that the conductive layer is formed by vapor deposition, and the conductive layer and the wiring connection part are connected by vapor-depositing the wiring connection part during the vapor deposition.
[0014]
With such a structure, the conductive reflective layer close to the photoelectric conversion element is fixed at a constant potential, and does not fluctuate electrically due to external noise or static electricity.
[0015]
BEST MODE FOR CARRYING OUT THE INVENTION
Next, embodiments of the present invention will be described in detail with reference to the drawings. First, the present invention is an invention for stabilizing the potential of a conductive layer closest to a photoelectric conversion element. In a radiation detector using a phosphor, a reflection layer is generally used on the side of the phosphor opposite to the photoelectric conversion element in order to increase sensitivity. In particular, in the case of an alkali halide phosphor, the reflective layer is generally made of a metal such as aluminum, which is the conductive layer closest to the photoelectric conversion element.
[0016]
Depending on the structure of the photoelectric conversion device, a conductive layer other than the reflective layer may be closest to the photoelectric conversion element. In this case, the conductive layer may be used as a target. As the alkali halide phosphor, CsI: Tl doped with thallium which is close to the spectral sensitivity characteristics of amorphous silicon as a photoelectric conversion element material is suitable. Even when another photoelectric conversion element material is used, a material suitable for light sensitivity characteristics may be used accordingly.
[0017]
Various wirings (bias lines, signal lines, gate lines, ground lines, and the like) included in the photoelectric conversion panel on which the photoelectric conversion elements are formed are connected to an external electric mounting board by bonding pad portions. By diverting a part of the wiring fixed to the potential or providing a dedicated wiring, it is possible to connect the conductive layer to a fixed potential while maintaining a simple structure. The connection pattern may use any electrode in the vertical direction of the panel.
[0018]
However, it is necessary to avoid a combination of materials that cause secondary disasters such as corrosion due to contact with the conductive layer. The connection position with the conductive layer is preferably provided between the photoelectric conversion element area having many patterns and the bonding pad portion. When a hole for opening the bonding pad portion is formed in the protective layer of the photoelectric conversion panel and a hole for wiring connection is formed at the same time, the configuration of the present invention can be realized without increasing the number of steps.
[0019]
In the case where the reflection layer is formed on the photoelectric conversion panel by means such as vapor deposition, connection can be made by vapor deposition in the above-mentioned opening. Also in this case, there is no need to increase the number of steps. Aluminum, aluminum alloy, silver, silver alloy, gold, or the like having high reflectivity may be used as the material of the reflective layer. Usually, aluminum, molybdenum, or the like is often used for the wiring on the photoelectric conversion panel side. Therefore, it is better to use aluminum or an alloy thereof for the material of the reflective layer. In order to improve the coverage of the deposition material, it is more preferable that the cross section of the opening of the protective layer has a slope. For that purpose, dry etching may be performed chemically.
[0020]
In the case where a structure including a reflective layer is incorporated into a photoelectric conversion element by a method such as bonding, electrical connection may be made between the opening and a conductive resin or the like. Regardless of the connection by direct vapor deposition or the connection by bonding, the structure is simpler than the configuration in which the connection is directly taken out to the outside, and there is no need to expose the reflection film in the middle of the process.
[0021]
The connection portion is provided at a position other than the element area and the surrounding bonding pad portion. At least one connection portion is sufficient as a whole. However, when the photoelectric conversion panel is large enough for chest imaging, the resistance component of the conductive layer is taken into consideration. , Column, and Raw directions are more preferably symmetrical. In the case of such a structure, the peripheral sealing performed at the end can be easily performed.
[0022]
(1st Embodiment)
Next, specific embodiments of the present invention will be described. FIG. 1 is a sectional view showing the configuration of the first embodiment of the radiation detecting apparatus according to the present invention. FIG. 1 shows a cross-sectional view of the radiation detection panel. In FIG. 1, the same parts as those of the conventional apparatus of FIG. 12 are denoted by the same reference numerals. An alkali halide phosphor (CsI: Tl) 7 is directly deposited on the photoelectric conversion panel 100, and a reflective layer 9 made of aluminum or the like is formed with a protective layer 8 interposed therebetween.
[0023]
The reflection layer 9 is connected to the wiring connection portion 3-e through an opening provided in the protection layer 5 made of SiN or the like. The wiring connection section 3-e is connected to the PCB 53 via the bonding pad section 4, the ACF 51, and the flexible board 52. The fixed potential is fixed from the PCB 53 side. In this embodiment, the PCB 53 is dropped to GND.
[0024]
The reflection layer 9 is bonded to the aluminum sheet 400. The aluminum sheet 400 is made up of an adhesive material 41, an aluminum portion 42, and a protective layer 43. The reflective layer 9 is bonded to the aluminum portion 42 by the adhesive material 41, and the aluminum portion 42 is dropped to a constant potential by another means. I have. 21 is a sealing part. With such a structure, more stable noise removal characteristics can be obtained.
[0025]
FIG. 2 is a sectional view showing a state where the radiation detection panel of FIG. 1 is incorporated in a mechanical chassis. 1 are given the same reference numerals. The radiation detection panel 100 is bonded to a chassis base 69 with a damper agent 70. Noise generated from the A / D conversion board 61 is shielded by metal shield plates 62 and 63. External noise from below and from the lateral direction is shielded by the metal shield plate 62, the metal chassis frame 66, and the metal shield plate 64, and noise from above is shielded by the aluminum sheet 400 provided on the radiation detection panel. I have. 65 is a heat radiating member, 67 is a cover, 68 is a maintenance cover, and 71 is a screw.
[0026]
FIG. 3 is a plan view of the photoelectric conversion panel viewed from above, and shows the vicinity of the wiring connection portion 3-e in detail. The wiring from one flexible cable (not shown) is connected by the bonding pad section 4 as shown in FIG. 3, and most of the wiring is connected to the photoelectric conversion element through the wiring 3-a. The constant potential wiring 3-d provided at the end is connected to the wiring connection part 3-e, and the reflection layer 9 has a constant potential through the wiring connection part 3-e, the constant potential wiring 3-d, the bonding pad part 4, and the like. It is connected to the.
[0027]
In a portion 5-b surrounded by a broken line, the wiring is exposed at a portion where the protective layer 5 is removed. This corresponds to the opening of the protective layer 5 described above. 6-a indicated by a dashed line is a boundary portion on which the aluminum reflective layer 9 is deposited, and thus is also deposited on the wiring connection portion 3-e.
[0028]
FIG. 4 is a plan view showing the arrangement of the wiring connection portions 3-e on the photoelectric conversion panel. In particular, when the photoelectric conversion panel is large, such as for chest imaging, there is a risk that an inclined potential distribution is generated in the panel due to the effect of the resistance component of aluminum, and therefore, as shown in FIG. It is desirable to arrange them symmetrically with good balance throughout.
[0029]
5 to 8 are cross-sectional views showing steps of manufacturing the radiation detection device of the present invention. Hereinafter, the manufacturing method will be described. First, as shown in FIG. 5A, a photoelectric conversion element 2 and related wirings are formed on a substrate 1 such as glass using an amorphous silicon semiconductor process. At this time, the patterns of the wiring 3-a, the constant potential wiring 3-d, the wiring connection portion 3-e, and the bonding pad portion 4 are formed in advance. After that, the protective layer 5 is formed. As the protective layer 5, inorganic SiN or the like having high moisture resistance is desirable.
[0030]
Next, as shown in FIG. 5B, a resist 5-a is applied and exposed and developed to remove the resist from the bonding pad portion 4 and the wiring connection portion 3-e. Further, as shown in FIG. 5C, through a dry etching process, the bonding pad portion 4 and the protective layer 5 of the wiring connection portion 3-e are simultaneously removed by etching, and the used resist is removed. The portion of the protective layer 5 to be removed at the same time corresponds to 5-b in FIG. At this time, it is desirable that the etched end face be tapered to increase the coverage of the aluminum thin film to be deposited later.
[0031]
Subsequently, as shown in FIG. 6A, a second protective layer 6 made of PI or the like is coated on the protective layer 5. In the case of using a spin coater for applying PI, it is necessary to protect the uncoated portion with a masking tape. When a slit coater or the like is used, a desired area can be coated without performing a masking process. The second protective layer 6 may be deleted if there is no problem in the characteristics and reliability of the sensor.
[0032]
Next, as shown in FIG. 6B, an alkali halide phosphor 7 is vapor-deposited on the photoelectric conversion element 2 on the second protective layer 6 by mask deposition. Subsequently, as shown in FIG. 7A, an organic protective layer 8 such as parylene is deposited as a moisture-resistant protective layer of the alkali halide phosphor 7 with a mask 8-a. The thickness of the deposited film is desirably 20 μm or less in consideration of the deterioration of the resolution. After vapor deposition, the organic film may be cut while removing the masking. FIG. 7B shows a state after the mask is extracted.
[0033]
Next, as shown in FIG. 8A, an aluminum thin film (reflection layer) 9 is deposited by a method such as sputtering. At this time, a mask 9-a is applied to avoid vapor deposition on the bonding pad portion 4, but vapor deposition is performed on the wiring connection portion 3-e, and the wiring connection portion 3-e and the reflection layer 9 are electrically connected. . Finally, as shown in FIG. 8B, the mask 9-a is extracted to complete the process.
[0034]
By using such a method, the conductor film can be connected to a constant potential in exactly the same process as in the related art. Therefore, the performance of the radiation detection device can be improved without increasing the cost.
[0035]
Further, since a step of removing the protective layer or the like is unnecessary, the risk of destruction of the reflective layer when the protective layer is removed when the reflective layer is directly dropped to the external GND can be completely eliminated. The subsequent step of bonding the aluminum sheet 400 and the step of assembling the aluminum sheet 400 to the mechanical chassis are not essential to the present invention, and thus the description is omitted.
[0036]
Next, the effect of reducing the influence of noise will be described using an example in which the MIS sensor 501 and the TFT 502 are used as photoelectric conversion elements. FIG. 9 shows a schematic sectional view thereof. 1 are given the same reference numerals. The potential of the lower electrode 201-b slightly changes due to carriers generated by light incident on the active layer 203-b of the MIS sensor unit 501. The drain electrode 30-b connected to the lower electrode 201-b also changes at the same time. This small potential difference is sent out to the signal line 30-a by the switching of the TFT 502, and the reading is completed.
[0037]
Here, most of the electromagnetic noise incident from the outside is absorbed by the aluminum sheet 400 (the aluminum part 42), but depending on the frequency component, there is a case where the electromagnetic noise penetrates this and reaches the reflection layer 9. Further, if there is a sudden generation of static electricity, a magnetic field is generated, which may reach the reflective layer 9.
[0038]
In this embodiment, since the potential of the reflective layer 9 is fixed at a constant potential through the panel, the drain electrode 30-b and the signal line 30-a do not become unstable. Therefore, an original image can be obtained. For example, when the image is used in the medical diagnosis field, the risk of misdiagnosis can be eliminated. Although the MIS sensor and the TFT are used in FIG. 9, the present invention is also effective when a PIN sensor or a C-MOS sensor is used.
[0039]
Thus, in the present embodiment, a simple and easy-to-manufacture structure for stabilizing the potential of the conductive layer located near the photoelectric conversion element can be provided at low cost.
[0040]
Here, when the reflection layer is connected to GND by a conventional method, a part of the protective layer 10 in FIG. 12 is peeled off, and for example, the GND is removed from the part where the protective layer is peeled off using a component such as a metal plate. Need to be connected to However, in this case, although it is necessary to seal up to the back surface of the metal plate or the like, it is difficult to completely seal using the coating resin 15 or the like, and the structure is difficult to seal. In the present embodiment, there is no such difficulty in the sealing, and the surroundings can be easily sealed by the sealing portion 21 as shown in FIG.
[0041]
(Second embodiment)
FIG. 10 is a sectional view showing a second embodiment of the present invention. 1 are given the same reference numerals. An alkali halide phosphor (CsI: Tl) 7 is directly vapor-deposited on the photoelectric conversion panel 100, and a reflection sheet 800 is bonded with a protective layer 8 interposed therebetween. The reflection sheet 800 includes a reflection layer 82 made of aluminum or the like, a protection layer 83 made of PET or the like for protecting aluminum, and an adhesive layer 81 made of an adhesive or the like. The adhesive layer 81 has a structure that does not reach the wiring connection portion 3-e.
[0042]
The reflection layer 82 of aluminum or the like is connected to the wiring connection portion 3-e by the conductive layer 44. The structure for setting the wiring connection portion 3-e to a constant potential is the same as in the first embodiment. In this embodiment, since aluminum does not use a vapor-deposited film, it is possible to form a foil of about several tens to several hundreds μm in consideration of electric noise. Therefore, the aluminum sheet 400 used only for noise as described in the first embodiment is not required. Since the protective layer 8 and the adhesive layer 81 are between the phosphor 7 and the reflective layer 82, the total thickness is preferably suppressed from several μm to several tens μm. With such a structure, more stable characteristics can be obtained.
[0043]
The manufacturing process of the present embodiment is the same as that of the first embodiment up to FIG. 5, FIG. 6, and FIG. 7, but thereafter, a conductive adhesive is potted on the wiring connection portion, and the reflection sheet 800 is laminated. May be bonded together. In the present embodiment, the structure can be simpler than in the first embodiment. In addition, sealing can be easily performed, and sealing performance can be improved.
[0044]
(Third embodiment)
FIG. 11 is a sectional view showing a third embodiment of the present invention. 1 are given the same reference numerals. A scintillator 900 is attached to the photoelectric conversion panel 100 with an adhesive layer 14. The scintillator 900 has a base 13 made of amorphous carbon or the like, a phosphor 7 made of a ride as an alkali, a reflective layer 9 made of aluminum or the like, a protective layer 8 for protecting the phosphor 7, and a protection for protecting the reflective layer. It is constituted by layers 11 and 12.
[0045]
Also in this case, the adhesive layer 14 does not reach the wiring connection portion 3-e. The reflection layer 9 is connected from the opening 9-b of the protective layer 11 to the wiring connection portion 3-e by the conductive layer 44. The openings 9-b can be created by masking when coating the protective layer 11. Further, if a slit coater is used, there is no need for masking. That is, there is no danger of peeling off the reflective layer 9. The structure for setting the wiring connection portion 3-e to a constant potential is the same as in the first embodiment.
[0046]
Further, in the present embodiment, since the reflective layer 9 obtained by vapor deposition is thin as in the first embodiment, an aluminum sheet 400 is attached. With such a structure, more stable characteristics can be obtained.
[0047]
The manufacturing process is the same as that of the first embodiment up to FIG. 5, FIG. 6, and FIG. 7, but thereafter, a conductive adhesive is potted on the wiring connection portion 3-e, and the adhesive is applied to the photoelectric conversion element portion. May be applied and bonded while aligning the opening 9-b of the scintillator 900 with the wiring connection portion 3-e. In this embodiment, the same effects as in the first and second embodiments can be obtained.
[0048]
【The invention's effect】
As described above, according to the present invention, since the conductor layer is connected to a constant potential through the constant potential wiring of the photoelectric conversion panel, a step such as peeling off the protective layer is not necessary. It is possible to prevent the danger of being lost. In addition, a simple and low-cost structure and a structure that is easy to seal can be provided, and a radiation detection device resistant to external noise and static electricity can be realized.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view illustrating a first embodiment of a radiation detecting apparatus according to the present invention.
FIG. 2 is a sectional view showing a state where the photoelectric conversion panel of FIG. 1 is incorporated in a chassis.
FIG. 3 is a plan view showing a wiring connection part of FIG. 1 in detail.
4 is a plan view showing an arrangement of a wiring connection portion on the photoelectric conversion panel of FIG. 1; FIG. 5 is a cross-sectional view showing a manufacturing process of the radiation detection device of FIG. 1;
FIG. 6 is a cross-sectional view illustrating a manufacturing process of the radiation detection apparatus of FIG.
FIG. 7 is a cross-sectional view showing a manufacturing process of the radiation detection device of FIG.
FIG. 8 is a cross-sectional view illustrating a manufacturing process of the radiation detection apparatus of FIG.
FIG. 9 is a schematic cross-sectional view showing an example in which an MIS sensor and a TFT are used as photoelectric conversion elements in the embodiment of FIG.
FIG. 10 is a sectional view showing a second embodiment of the present invention.
FIG. 11 is a sectional view showing a third embodiment of the present invention.
FIG. 12 is a cross-sectional view illustrating a conventional radiation detection element.
FIG. 13 is a cross-sectional view showing a conventional radiation detection apparatus.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Substrate 2 Photoelectric conversion element 3-a Wiring 3-d Constant potential wiring 3-e Wiring connection part 4 Bonding pad part 5 Protective layer 6 Protective layer 6-a Boundary part 7 Alkali halide phosphor 8 Protective layer 8-a For vapor deposition Mask 9 Reflective layer 9-a Evaporation mask 14 Adhesive layer 21 Sealing part 41 Adhesive 42 Aluminum part 43 Protective layer 44 Conductive layer 51 ACF
52 Flexible board 53 PCB board 61 A / D conversion board 62 Metal shielding plate 63 Metal shielding plate 64 Metal shielding plate 65 Heat dissipation member 66 Metal chassis frame 67 Cover 68 Maintenance cover 69 Housing base plate 70 Damper material 71 Screw 81 Adhesive layer 82 Reflective aluminum 83 Protective layer 100 Photoelectric conversion panel 201-a Gate electrode 201-b Sensor lower electrode 202-a Gate insulating film 202-b Sensor insulating film 203-a TFT active layer 203-b Sensor active layer 204-a Ohmic contact Layer 204-b Sensor upper electrode 300 Scintillator part 400 Aluminum sheet 501 MIS type sensor part 502 TFT part 800 Reflection sheet 900 Scintillator

Claims (1)

In a radiation detection device in which a wavelength converter and a conductor layer are arranged on a photoelectric conversion panel on which a photoelectric conversion element is formed, the conductor layer is connected to a constant potential through a constant potential wiring of the photoelectric conversion panel. Characteristic radiation detector.

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