This application claims the benefit of priority to Japanese Patent Application Number 2022-060818 filed on Mar. 31, 2022. The entire contents of the above-identified application are hereby incorporated by reference.
The disclosure relates to a radiation detection module and a manufacturing method for the radiation detection module.
With the development of image processing techniques, various image diagnostic apparatuses are widely used also in the medical field. In a diagnostic apparatus using radiation such as X-rays, a radiation Flat Panel Detector (FPD) capable of directly converting radiation transmitted through a body or an object into digital data is used. For example, JP 2011-17683 A discloses such an FPD.
An object of the disclosure is to provide a radiation detection module capable of acquiring a radiation image with higher sensitivity and higher resolution and a manufacturing method for the radiation detection module.
A radiation detection module according to an embodiment of the disclosure includes an active matrix substrate including a support substrate including a first main surface and a second main surface positioned at an opposite side to the first main surface, the first main surface including a first region and a second region surrounding the first region, and a plurality of pixels one-dimensionally or two-dimensionally arrayed in the first region of the first main surface, the plurality of pixels each of which includes a switching element and a photoelectric conversion element electrically connected to the switching element, and a scintillator covering the photoelectric conversion elements of the plurality of pixels, and a thickness of the support substrate in the first region is smaller than a thickness of the support substrate in the second region.
According to the embodiment of the disclosure, there are provided a radiation detection module capable of acquiring a radiation image with higher sensitivity and higher resolution and a manufacturing method for the radiation detection module.
The disclosure will be described with reference to the accompanying drawings, wherein like numbers reference like elements.
An embodiment of the disclosure will be described below with reference to the drawings. The disclosure is not limited to the following embodiment, and appropriate design changes can be made within a scope that satisfies the configuration of the disclosure. Further, in the description below, the same reference signs may be used in common among the different drawings for the same portions or portions having similar functions, and repetitive descriptions related to the portions may be omitted. Further, each configuration described in the embodiment and other embodiments may be combined or modified as appropriate within a range that does not depart from the gist of the disclosure. For ease of explanation, in the drawings, which will be referenced below, the configuration may be simplified or schematically illustrated, or some of the constituent members may be omitted. Dimensional ratios between the constituent members illustrated in each of the drawings are not necessarily indicative of actual dimensional ratios. A “row direction” means a horizontal direction of a screen of a display device, and a “column direction” means a vertical direction of the screen of the display device.
A radiation detection module according to the disclosure is used for an X-ray photographing apparatus using radioactive rays such as X-rays, or an X-ray FPD to be used for X-ray photographing, for example.
The radiation detection module 101 includes an active matrix substrate 10 and a scintillator 50. Additionally, the active matrix substrate 10 includes a support substrate 20 and a pixel array 30 including a plurality of pixels.
The pixel array 30 is formed on the support substrate 20.
The support substrate 20 includes a first main surface 20a and a second main surface 20b positioned at the opposite side to the first main surface. As will be described later, the second main surface 20b is a radiation incident surface of the radiation detection module 101. The first main surface 20a includes a first region 20r1 including the center of the first main surface 20a, the first region 20r1 being positioned at the center of the first main surface 20a, and a second region 20r2 positioned around the first region 20r1.
The first region 20r1 has, for example, a rectangular shape, and the pixel array 30 is positioned in the first region 20r1. The second region 20r2 surrounds the first region 20r1, and is positioned along the outer periphery of the first main surface 20a. It is preferable that the second region 20r2 continuously surround the first region 20r1 without a break.
The support substrate 20 includes a recessed portion 21 in a region of the second main surface 20b corresponding to the first region 20r1. By providing the recessed portion 21, a thickness t1 of the support substrate 20 in the first region 20r1 is smaller than a thickness t2 of the support substrate 20 in the second region 20r2. The thickness t1 is preferably equal to or less than ½ of the thickness t2, and is more preferably equal to or less than ⅓ of the thickness t2. The recessed portion 21 can be formed by wet etching, dry etching, sand blasting, mechanical grinding or polishing, as described later.
The recessed portion 21 includes a bottom portion 21b. When viewed in a plan view, that is, when viewed from a direction perpendicular to the first main surface 20a or the second main surface 20b of the support substrate 20, the bottom portion 21b overlaps the first region 20r1, and an outer edge of the bottom portion 21b and an outer edge of the first region 20r1 coincide with each other. In the examples illustrated in
In
A size of the support substrate 20 is determined according to the application and specifications of a radiation FPD manufactured by using the radiation detection module 101. For example, the support substrate 20 has a rectangular shape with a vertical length of 50 mm to 500 mm and a horizontal length of 50 mm to 500 mm, and the first region 20r1 has a rectangular shape with a vertical length of 50 mm to 430 mm and a horizontal length of 50 mm to 430 mm. Additionally, a width w of the second region is from 5 mm to 50 mm. The thickness t1 of the support substrate 20 in the first region 20r1 is, for example, from 0.05 mm to 0.3 mm. Additionally, the thickness t2 in the second region 20r2 is, for example, 0.4 mm to 0.7 mm.
The support substrate 20 is preferably made of an insulating material that hardly absorbs radiation to be detected. For example, the support substrate 20 may be a glass substrate to be used for a liquid crystal display panel.
The pixel array 30 is disposed in the first region 20r1 of the support substrate 20.
The pixel array 30 includes a plurality of pixels 31 one-dimensionally or two-dimensionally arrayed. In the present embodiment, the plurality of pixels 31 are two-dimensionally arranged in the row direction and the column direction. Each of the pixels 31 includes a switching element and a photoelectric conversion element electrically connected to the switching element. The switching element is, for example, an active element such as an MIM element, a TFT or the like, and in the present embodiment, the pixel 31 includes a TFT 32. The TFT 32 includes, for example, an oxide semiconductor layer containing at least one element selected from the group consisting of In, Ga, and Zn, or a Si-semiconductor layer. The oxide semiconductor layer and the Si semiconductor layer may have various types of crystallinity such as polycrystal, microcrystal, a c-axis orientation distribution or the like.
The photoelectric conversion element receives scintillation light emitted from a scintillator, which will be described later, and generates charges by photoelectric conversion. The photoelectric conversion element is, for example, an element including a semiconductor layer and having various structures capable of separating a hole-electron pair generated by a photon incident on the semiconductor layer. In the present embodiment, the pixel 31 includes a photodiode 33. The photodiode 33 includes, for example, an i-type Si semiconductor layer, and a p-type Si semiconductor layer and an n-type Si semiconductor layer that sandwich the i-type Si semiconductor layer. The pixel 31 may further include an amplifier circuit that amplifies charges generated in the photodiode 33.
The pixel array 30 includes a plurality of scanning lines 34 and a plurality of data lines 35. For example, the gates of the TFTs 32 of a plurality of pixels 31 arranged in the column direction are connected to one scanning line 34. In addition, the sources of the TFTs 32 of the plurality of pixels 31 arranged in the column direction are connected to one data line 35.
In the pixel array 30, various insulating layers and interlayer insulating films are disposed between constituent elements that need to be electrically separated, such as the TFT 32, the photodiode 33, the scanning line 34, the data line 35 and the like. These insulating layers and interlayer insulating films are not illustrated in
The radiation detection module 101 further includes a scanning line drive unit 42 that is a driver of the pixel array 30 and a charge detection unit 41. The scanning line drive unit 42 includes substrates 42d and terminals 42c individually provided on the substrates 42d, and drive circuits for sequentially selecting the plurality of scanning lines 34 are formed on the substrates 42d. A portion of the substrate 42d including at least the terminal 42c is positioned in the second region 20r2, and is supported by the support substrate 20. The scanning line drive unit 42 is connected to the scanning lines 34 via the terminals 42c, and is electrically connected to the TFTs 32 of the plurality of pixels 31. Although the scanning line drive unit 42 is divided into two or more substrates in the present embodiment, the scanning line drive unit 42 may be formed on one substrate.
Similarly, the charge detection unit 41 includes substrates 41d and terminals 41c individually provided on the substrates 41d, and charge detection circuits for receiving charges accumulated in the photodiodes 33 and converting the charges into electric signals are formed on the substrates 41d. A portion of the substrate 41d including at least the terminal 41c is positioned in the second region 20r2, and is supported by the support substrate 20. The charge detection unit 41 is connected to the data lines 35 via the terminals 41c, and is electrically connected to the TFTs 32 of the plurality of pixels 31. In the present embodiment, the charge detection unit 41 is divided into two or more substrates, but the charge detection unit 41 may be formed on one substrate.
The scintillator 50 emits scintillation light when radiation transmitted through a body or an object is incident thereon. The scintillator 50 covers the photodiodes 33 that are photoelectric conversion elements of the plurality of pixels 31. For example, the scintillator 50 has a sheet shape, and is bonded to the plurality of pixels 31 with an adhesive layer 51 such as an OCA interposed therebetween. The scintillator 50 may be a vapor deposition film.
The scintillator 50 is made of a material corresponding to radiation to be used. The radiation may be X-rays, α-rays, γ-rays, or the like. X-rays are widely used for a medical or industrial radiation FPD. As the scintillator 50 that detects X-rays, a single crystal or polycrystal material such as Thallium activated Cesium Iodide (Tl:CsI), Gadolinium OxySulfide (GOS) or the like can be used.
An operation of the radiation detection module 101 will be described with reference to
According to the radiation detection module 101 of the present embodiment, the radiation X is made incident on the scintillator 50 from the second main surface 50b adjacent to the photodiodes 33. Thus, the generated scintillation light is incident on the photodiodes 33 without transmitting through the scintillator 50 in the thickness direction. Thus, attenuation or diffusion of the scintillation light in the scintillator 50 can be suppressed, and a radiation image with high sensitivity and high resolution can be acquired.
In a radiation FPD employing such a detection method, it is necessary to transmit radiation through a support substrate that supports a pixel array. The radiation detection module 101 according to the present embodiment can suppress attenuation of radiation at the support substrate 20, because the support substrate 20 has the small thickness t1 in the first region 20r1 where the pixel array 30 is positioned. Thus, the radiation can be detected with high sensitivity.
In addition, since the thickness t2 in the second region 20r2 that is the outer peripheral portion of the support substrate 20 is large, it is possible to secure the strength of the support substrate 20 while reducing the thickness t1 in the first region 20r1. Further, the drivers of the active matrix substrate 10 such as the charge detection unit 41, the scanning line drive unit 42 and the like are connected to the pixel array 30 in the second region 20r2 of the support substrate 20. For this reason, even when stresses are applied to the support substrate 20 from the outside through the substrates of the drivers and the connection terminals, since the thickness in the second region 20r2 of the support substrate 20 is large, deformation or damage of the support substrate 20 is suppressed.
When the thicknesses of the glass substrates were 0.1, 0.2, 0.5, and 0.7 mm, the transmittances were 99.3, 98.7, 94.6, and 92.2%, respectively, as compared with the case where no glass substrate was provided. This indicates that attenuation of X-rays at the support substrate 20 can be suppressed and X-rays with high intensity can be incident on the scintillator 50 by reducing the thickness of the support substrate 20.
On the other hand, according to the radiation detection module 101 of the present embodiment, the support substrate 20 is thicker in the second region 20r2 around the first region 20r1. Thus, it is possible to ensure the strength of the support substrate 20 and to suppress cracking or chipping of the support substrate 20 during manufacturing of the radiation detection module 101 or during manufacturing of an FPD with the completed radiation detection module. In addition, handling of the radiation detection module 101 during these processes can be facilitated.
Next, a manufacturing method for the radiation detection module 101 will be described.
The manufacturing method for the radiation detection module 101 according to the present embodiment includes a process (A) of forming a plurality of pixels on a support substrate and a process (B) of removing a part of the support substrate from a second main surface. In addition, a process (C) of disposing the scintillator and a process (D) of mounting the drivers are further included. Each process will be described in detail below.
As illustrated in
First, the pixel array 30 including the plurality of pixels 31 is formed on the first main surface 20a of the support substrate 20′ (S1, S2). To be specific, for example, a plurality of TFTs 32 are formed in the first region 20r1 of the first main surface 20a of the support substrate 20′ by using a semiconductor manufacturing technique to be used for a liquid crystal display device (S1). Further, as illustrated in
As illustrated in
(3) Process (B) of Removing Part of Support Substrate from Second Main Surface
As illustrated in
The charge detection unit 41 and the scanning line drive unit 42 are prepared, and the scanning line drive unit and the charge detection unit are mounted in the second region 20r2 of the first main surface 20a of the support substrate 20 (S6). As illustrated in
(5) Incorporation into Housing
Thereafter, the radiation detection module 101 is incorporated into a housing to complete the radiation FPD.
According to the manufacturing method for the radiation detection module 101 of the present embodiment, after the pixel array 30 is formed on the support substrate 20′ and the scintillator 50 is disposed, a part of the support substrate 20′ is removed. Thus, when the pixel array 30 is formed and the scintillator 50 is disposed, cracking or chipping of the support substrate 20′ is suppressed. In addition, since the support substrate has a uniform thickness in forming the pixel array 30, even when the support substrate 20′ is heated and cooled in forming the pixel array 30, the entire support substrate 20′ uniformly expands and contracts, and thus, deformation of the support substrate 20′ and generation of stress in the structure of the pixel array 30 to be formed are suppressed.
In addition, since the thickness of the support substrate 20 where the recessed portion 21 is formed is large in the second region 20r2, an appropriate mechanical strength is secured even when the charge detection unit 41 and the scanning line drive unit 42 are mounted, and cracking or chipping of the support substrate 20 is suppressed.
Note that in the embodiment described above, a part of the support substrate is removed after the scintillator 50 is formed. However, when the scintillator 50 having a sheet shape is used, the part of the support substrate may be removed after the scintillator 50 is formed. To be more specific, as illustrated in
The radiation detection module and the manufacturing method for the radiation detection module of the disclosure are not limited to the above-described embodiment, and various modifications are possible. For example, the shapes of the support substrate 20 and the recessed portion 21, the circuit configuration of the pixel array, and the like are not limited to those in the above-described embodiment. In addition, in the manufacturing method for the radiation detection module, a plurality of processes may be performed in combination, or conversely, one process may be divided into two or more processes.
The radiation detection module and the manufacturing method for the radiation detection module of the disclosure can also be described as follows.
A radiation detection module according to a first configuration includes an active matrix substrate and a scintillator. The active matrix substrate includes a support substrate including a first main surface and a second main surface positioned at an opposite side to the first main surface, the first main surface including a first region and a second region surrounding the first region, and a plurality of pixels one-dimensionally or two-dimensionally arrayed in the first region of the first main surface, the plurality of pixels each of which includes a switching element and a photoelectric conversion element electrically connected to the switching element. The scintillator covers the photoelectric conversion elements of the plurality of pixels. A thickness of the support substrate in the first region is smaller than a thickness in the second region.
With the radiation detection module according to the first configuration, when radiation is made incident from the second main surface, scintillation light is incident on the photoelectric conversion element without being transmitted through the scintillator in a thickness direction. Thus, attenuation and diffusion of the scintillation light in the scintillator are suppressed, and it is possible to acquire a radiation image with high sensitivity and high resolution. In addition, since the thickness of the support substrate is small in the first region where the plurality of pixels are positioned, attenuation of the radiation at the support substrate is suppressed, and high detection sensitivity of the radiation can be achieved. In addition, since a thickness of the second region 20r2 that is an outer peripheral portion of the support substrate is large, it is possible to ensure the strength of the entire support substrate while making the thickness of the first region small.
In a radiation detection module according to a second configuration, in the first configuration, the second region may be positioned along an outer periphery of the first main surface of the support substrate.
In a radiation detection module according to a third configuration, in the first or second configuration, the thickness of the support substrate in the first region may be equal to or less than ½ of the thickness of the support substrate in the second region.
In a radiation detection module according to a fourth configuration, in the first to third configurations, the support substrate may include a recessed portion in a region of the second main surface corresponding to the first region.
A radiation detection module according to a fifth configuration, in the first to fourth configurations, may further include a scanning line drive unit electrically connected to the switching elements of the plurality of pixels, and a charge detection unit electrically connected to the switching elements of the plurality of pixels, and at least a part of the scanning line drive unit and at least a part of the charge detection unit may be positioned in the second region of the first main surface of the support substrate. Since at least the part of the scanning line drive unit and at least the part of the charge detection unit are disposed in the second region of the support substrate, even when stress is applied to the support substrate 20 from the outside via substrates and connection terminals of the scanning line drive unit and the charge detection unit, deformation or damage of the support substrate is suppressed.
In a radiation detection module according to a sixth configuration, in the first to fifth configurations, the second main surface of the support substrate may be a radiation incident surface.
In a radiation detection module according to a seventh configuration, in the first to sixth configurations, each of the plurality of pixels may further include an amplifier circuit configured to amplify charges generated by the photoelectric conversion element.
A manufacturing method for a radiation detection module according to an eighth configuration includes (A) forming a plurality of pixels each of which includes a switching element and a photoelectric conversion element in a first region of a support substrate including a first main surface and a second main surface positioned at an opposite side to the first main surface, the first main surface including the first region and a second region surrounding the first region, and (B) removing a part of the support substrate from the second main surface and then forming a recessed portion in a region of the second main surface corresponding to the first region, and making a thickness of the support substrate in the first region smaller than a thickness of the support substrate in the second region.
The manufacturing method for the radiation detection module according to the eighth configuration suppresses cracking or chipping of the support substrate in forming a pixel array and disposing a scintillator. In addition, since the support substrate has a uniform thickness when the pixel array is formed, even when the support substrate is heated and cooled when the pixel array is formed, the entire support substrate uniformly expands and contracts, and deformation of the support substrate and generation of stress in the structure of the pixel array to be formed are suppressed.
A manufacturing method for a radiation detection module according to a ninth configuration may further include, in the eighth configuration, (C) disposing a scintillator that covers the photoelectric conversion elements of the plurality of pixels before (B).
A manufacturing method for a radiation detection module according to a tenth configuration may further include, in the eighth configuration, (C) disposing a scintillator that covers the photoelectric conversion elements of the plurality of pixels after (B).
In a manufacturing method for a radiation detection module according to an eleventh configuration, in the ninth or tenth configuration, in (C), the scintillator may have a sheet shape, and the scintillator having the sheet shape may be bonded to the plurality of pixels with an adhesive layer interposed between the scintillator and the plurality of pixels.
In a manufacturing method for a radiation detection module according to a twelfth configuration, in the ninth configuration, in (C), a material of the scintillator may be deposited on the plurality of pixels by vapor deposition and then the scintillator may be formed.
A manufacturing method for a radiation detection module according to a thirteenth configuration may further include, in the eighth to tenth configurations, after (B), (D) mounting a scanning line drive unit and a charge detection unit in the second region of the first main surface of the support substrate and electrically connecting the scanning line drive unit and the charge detection unit to the switching elements of the plurality of pixels. Since the charge detection unit and the scanning line drive unit are disposed in the second region of the support substrate, deformation or damage of the support substrate is suppressed when the charge detection unit and the scanning line drive unit are mounted.
The radiation detection module and the manufacturing method for the radiation detection module according to the disclosure can be suitably used in various fields, and are suitably used for a medical X-ray FPD or the like.
While preferred embodiments of the disclosure have been described above, it is to be understood that variations and modifications will be apparent to those skilled in the art without departing from the scope and spirit of the disclosure. The scope of the disclosure, therefore, is to be determined solely by the following claims.
Number | Date | Country | Kind |
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2022-060818 | Mar 2022 | JP | national |