US-12628445-B2 - Radiation detector and radiation imaging system

US12628445B2US 12628445 B2US12628445 B2US 12628445B2US-12628445-B2

Abstract

A radiation detector comprising: a pixel array in which pixels each having a radiation detection element configured to convert radiation into charges and an amplification transistor configured to amplify a signal from the radiation detection element and output the amplified signal are arrayed in a matrix shape; and signal wiring provided for each pixel column, wherein the signal wiring does not overlap an active layer, in which the amplification transistor is arranged, in a plan view.

Inventors

Kazutaka Osawa
Takanori Watanabe
Tomona Yamaguchi

Assignees

CANON KABUSHIKI KAISHA

Dates

Publication Date: 20260512
Application Date: 20230512
Priority Date: 20220518

Claims (13)

1 . A radiation detector comprising: a pixel array in which pixels each having a radiation detection element configured to convert radiation into charges and an amplification transistor configured to amplify a signal from the radiation detection element and output the amplified signal are arrayed in a matrix shape; and signal wiring provided for each pixel column, wherein the signal wiring does not overlap an active layer, in which the amplification transistor is arranged, in a plan view, wherein the signal wiring includes at least two signal wiring lines arranged with respect to one pixel column, wherein the pixels have power supply wiring arranged parallel to the signal wiring line, wherein an interval between an adjacent signal wiring line is smaller than an interval between the signal wiring line, which is adjacent to the power supply wiring, and the power supply wiring, wherein the pixels include a reset transistor, and wherein the power supply wiring includes first power supply wiring that supplies a drain potential of the amplification transistor, second power supply wiring that supplies a well potential, and third power supply wiring that supplies a drain potential of the reset transistor.
2 . The radiation detector according to claim 1 , wherein the active layer in which the amplification transistor is arranged is a channel region of the amplification transistor.
3 . The radiation detector according to claim 1 , wherein the active layer in which the amplification transistor is arranged is a diffusion region of the amplification transistor.
4 . The radiation detector according to claim 1 , wherein the signal wiring lines are formed in a same layer as wiring that supplies a power supply voltage to the amplification transistor, and wherein the signal wiring lines are arranged to be adjacent to each other.
5 . The radiation detector according to claim 1 , wherein connection wiring that is provided for each amplification transistor and that is orthogonal to a corresponding one of the signal wiring lines is provided, wherein the signal wiring lines and the connection wiring are formed in different layers and electrically connected to each other via a via hole, and wherein plane layouts of the pixels are substantially same in shape except for the via hole.
6 . The radiation detector according to claim 5 , wherein each intersection between the signal wiring and the connection wiring, an overlapped region has substantially a same area.
7 . The radiation detector according to claim 1 , wherein the second power supply wiring is arranged between the first power supply wiring and the third power supply wiring.
8 . The radiation detector according to claim 1 , wherein the third power supply wiring is arranged between the first power supply wiring and the second power supply wiring.
9 . The radiation detector according to claim 1 , wherein the first power supply wiring, the second power supply wiring, and the third power supply wiring are arranged at an upper part of a region in which the amplification transistor is arranged.
10 . The radiation detector according to claim 1 , wherein the signal wiring is arranged at an upper part of a region in which the radiation detection element is arranged, and wherein the signal wiring includes at least three signal wiring lines per pixel column.
11 . The radiation detector according to claim 1 , wherein the radiation detector is of a surface irradiation type.
12 . A radiation imaging system comprising: the radiation detector according to claim 1 ; and a signal processing unit that processes a signal output from the radiation detector.
13 . A radiation imaging system comprising: the radiation detector according to claim 1 ; and a radiation source.

Description

BACKGROUND OF THE INVENTION Field of the Invention The present invention relates to a radiation detector and a radiation imaging system. Description of the Related Art Japanese Patent Application Laid-open No. 2019-87640 discloses a method for improving accuracy in detecting energy rays by defining the thickness of the detection region of an energy ray detector (radiation detector). Degradation possibly occurs when radiation is incident on the radiation detector. SUMMARY OF THE INVENTION The present invention has an object of providing a radiation detector having enhanced detection sensitivity. An aspect of the disclosure is a radiation detector comprising: a pixel array in which pixels each having a radiation detection element configured to convert radiation into charges and an amplification transistor configured to amplify a signal from the radiation detection element and output the amplified signal are arrayed in a matrix shape; and signal wiring provided for each pixel column, wherein the signal wiring does not overlap an active layer, in which the amplification transistor is arranged, in a plan view. According to the present invention, it is possible to provide a radiation detector having enhanced radiation resistance. Further features of the present invention will become apparent from the following description of exemplary embodiments with reference to the attached drawings. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagram showing the configuration of an imaging device according to a first embodiment; FIG. 2 is an equivalent circuit diagram of pixels according to the first embodiment; FIGS. 3A to 3C are top surface diagrams of a pixel according to the first embodiment; FIG. 4 is a diagram showing the configuration of an imaging device according to a second embodiment; FIG. 5 is an equivalent circuit diagram of pixels according to the second embodiment; FIGS. 6A to 6C are top surface diagrams of a pixel according to the second embodiment; FIG. 7 is a top surface diagram of pixels according to a third embodiment; FIGS. 8A to 8C are top surface diagrams of a pixel according to a fourth embodiment; FIGS. 9A to 9C are top surface diagrams of a pixel according to the fifth embodiment; FIGS. 10A to 10C are top surface diagrams of a pixel according to a sixth embodiment; FIGS. 11A to 11C are top surface diagrams of a pixel according to a seventh embodiment; FIG. 12 is a top surface diagram of pixels according to an eighth embodiment; FIG. 13 is a top surface diagram of pixels according to a ninth embodiment; FIG. 14 is a top surface diagram of pixels according to a tenth embodiment; FIG. 15 is a top surface diagram of pixels according to an eleventh embodiment; FIG. 16 is a schematic diagram for describing a radiation imaging system according to a twelfth embodiment; and FIG. 17 is a schematic diagram for describing a radiation imaging system according to a thirteenth embodiment. DESCRIPTION OF THE EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. Note that the following embodiments will show only specific examples of the technical thoughts of the present invention and will not intend to limit the present invention. The embodiments will describe plurality of characteristics. However, all the plurality of characteristics are not necessary for the invention, and the plurality of characteristics may be arbitrarily combined together. The sizes or positional relationships of members shown in the respective drawings will be exaggerated according to circumstances to make descriptions definite. Hereinafter, the same configurations will be denoted by the same symbols, and their descriptions will be omitted in some cases. The degradation of a radiation detector is understood as follows. When radiation is incident on the radiation detector, charges generated in an insulating layer are retained in the insulating layer. The charges retained in the insulating layer fluctuate the potential of the channel of an in-pixel transistor and shift a threshold. Therefore, the operating point of the in-pixel transistor is fluctuated. Further, the charges retained in the insulating layer change the width of the depletion layer of a PN junction part formed as the source, drain, or the like of the in-pixel transistor and fluctuate parasitic capacitance. Moreover, the charges retained in the insulating layer has an influence on the potential of a detection diode and increases a dark current. Alternatively, the operating point of a pixel circuit fluctuates when the charges retained in the insulating layer increase the dark current of a floating node. These factors due to the charges retained in the insulating layer have an influence on a sensor output and disables the output of a desired signal. Since the amount of the charges retained in the insulating layer increases according to the irradiation amount of radiation, a pixel output deviates from a d