JP-7856980-B2 - Photodetectors, X-ray imaging sensors, and electronic equipment

Inventors

• 初井 宇記
• 河村 隆宏
• 唐仁原 裕樹

Assignees

• 国立研究開発法人理化学研究所
• ソニーセミコンダクタソリューションズ株式会社

Dates

Publication Date

20260512

Application Date

20220325

Priority Date

20210428

Claims (18)

1. A semiconductor substrate including a photoelectric conversion region, A first conductivity type region is provided at the interface of one surface of the semiconductor substrate and connected to the first electrode, At the interface of the first surface, a second first conductivity region is provided around the first first conductivity region and connected to the second electrode, At the interface of the first surface, a third first conductivity region is provided around the second first conductivity region and is electrically floating , It comprises a second conductive region embedded and formed within the semiconductor substrate, The first conductivity type region extends in the direction of the other surface opposite to the first surface, and has an overhanging region that extends further horizontally towards the other surface side than the second conductivity type region. Light-receiving element.
2. The light-receiving element according to claim 1, wherein the semiconductor substrate further has a second conductivity type layer at the interface of the other surface facing the first surface.
3. The photodetector according to claim 1, wherein the third first conductivity type region is formed in multiple locations around the second first conductivity type region.
4. The light-receiving element according to claim 1, wherein the second first conductivity type region is provided continuously around the first first conductivity type region.
5. The light-receiving element according to claim 1, wherein the third first conductivity type region is provided continuously around the second first conductivity type region.
6. The light-receiving element according to claim 1, wherein the second first conductivity type region and the third first conductivity type region are arranged in that order around the first first conductivity type region, and have a polygonal planar shape with curved corners.
7. The photodetector according to claim 1 , wherein the second conductivity type region has an opening at a position opposite to the first conductivity type region.
8. The photodetector according to claim 1 , wherein the second conductivity type region has regions with different impurity concentrations.
9. The light-receiving element according to claim 2, wherein the first conductivity type region extends more in the other plane direction than the second and third conductivity type regions.
10. The photodetector according to claim 3, wherein the third first conductivity type regions, which are formed in multiple locations around the second first conductivity type region, have different line widths from each other.
11. The light-receiving element according to claim 3, wherein the line width of the multiple third first conductivity type regions formed around the second first conductivity type region is progressively wider as it moves away from the first first conductivity type region.
12. The light-receiving element according to claim 3, wherein the spacing between the multiple third first conductivity type regions formed around the second first conductivity type region is progressively wider towards the outside.
13. The photodetector according to claim 2, wherein the second conductivity layer and the second conductivity region have a higher impurity concentration than the semiconductor substrate.
14. The photodetector according to claim 1, wherein the semiconductor substrate is made of an intrinsic semiconductor.
15. It is equipped with multiple photodetectors that generate signal charges based on X-rays, The aforementioned light-receiving element is A semiconductor substrate including a photoelectric conversion region, A first conductivity type region is provided at the interface of one surface of the semiconductor substrate and connected to the first electrode, At the interface of the first surface, a second first conductivity region is provided around the first first conductivity region and connected to the second electrode, At the interface of the first surface, a third first conductivity region is provided around the second first conductivity region and is electrically floating , It has a second conductivity type region embedded and formed within the semiconductor substrate, The first conductivity type region extends in the direction of the other surface opposite to the first surface, and has an overhanging region that extends further horizontally towards the other surface side than the second conductivity type region. X-ray imaging sensor.
16. A pixel region in which multiple pixels are arranged, It has a peripheral region provided around the aforementioned pixel region, The X-ray imaging sensor according to claim 15 , wherein the semiconductor substrate has a depletion region in the pixel region and a neutral region in the peripheral region.
17. The X-ray imaging sensor according to claim 16, wherein the photodetector is provided for each of the plurality of pixels and is a pn junction type photodetector that applies a reverse bias between one surface of the semiconductor substrate and another surface facing the first surface.
18. Equipped with an X-ray imaging sensor, The aforementioned X-ray imaging sensor has a plurality of photodetectors that generate signal charges based on X-rays, The aforementioned light-receiving element is A semiconductor substrate including a photoelectric conversion region, A first conductivity type region is provided at the interface of one surface of the semiconductor substrate and connected to the first electrode, At the interface of the first surface, a second first conductivity region is provided around the first first conductivity region and connected to the second electrode, At the interface of the first surface, a third first conductivity region is provided around the second first conductivity region and is electrically floating , It comprises a second conductive region embedded and formed within the semiconductor substrate, The first conductivity type region extends in the direction of the other surface opposite to the first surface, and has an overhanging region that extends further horizontally towards the other surface side than the second conductivity type region. electronic equipment.

Description

This disclosure relates to a photodetector suitable for, for example, X-ray imaging for medical or non-destructive testing purposes, as well as an X-ray imaging sensor and electronic equipment equipped therewith. Solid-state imaging devices are used in a variety of applications, such as imaging devices in digital still cameras and video cameras, electronic devices such as mobile terminals with imaging capabilities, and electromagnetic wave sensors that detect various wavelengths other than visible light. Among solid-state imaging devices, there are APS (Active Pixel Sensors) equipped with an amplification element for each pixel, and CMOS (complementary MOS) image sensors (CIS) that read out the signal charge accumulated in a photodiode, which is a photoelectric conversion element, via a MOS (Metal Oxide Semiconductor) transistor are widely used. In sensors for scientific applications requiring high-sensitivity measurement, photodetectors (PIN photodiodes) with an integrated structure of a photoelectric conversion region and a floating diffusion (FD) region are used (see, for example, Patent Document 1). Such photodetectors are easy to manufacture due to their simple structure. Furthermore, an arbitrary potential difference can be applied to the pn junction forming the photoelectric conversion region. This makes it easy to increase the thickness of the photoelectric conversion region. Japanese Patent Application Publication No. 11-4012 Incidentally, in recent years, there has been a demand for the development of X-ray imaging sensors with high frame rates and low noise for scientific applications. To achieve this, it is necessary to reduce dark current, reduce capacitance, and improve readout speed. It is desirable to provide a photodetector, an X-ray imaging sensor, and electronic equipment that can achieve a reduction in dark current, a reduction in capacitance, and an improvement in readout speed. A light-receiving element according to one embodiment of the present disclosure comprises a semiconductor substrate including a photoelectric conversion region, a first conductivity type region provided at the interface of one face of the semiconductor substrate and connected to a first electrode, a second conductivity type region provided at the interface of one face around the first conductivity type region and connected to a second electrode, a third conductivity type region provided at the interface of one face around the second conductivity type region and electrically floating , and a second conductivity type region embedded and formed within the semiconductor substrate, wherein the first conductivity type region extends in the direction of the other face opposite to the one face and has an overhanging region that extends further horizontally on the other face side than the second conductivity type region . An X-ray imaging sensor according to one embodiment of the present disclosure comprises a plurality of photodetectors according to the above embodiment of the present disclosure, which generate signal charges based on X-rays. An electronic device according to one embodiment of the present disclosure is equipped with an X-ray imaging sensor according to the above embodiment of the present disclosure. In a photodetector, an X-ray image sensor, and an electronic device according to one embodiment of the present disclosure, a first conductivity type region is provided at the interface of one face of a semiconductor substrate including a photoelectric conversion region, and a second conductivity type region connected to a second electrode and a third electrically floating conductivity type region are arranged in this order around a first conductivity type region connected to a first electrode. This allows dark current generated at the interface of one face of the semiconductor substrate to be discharged from the second conductivity type region, preventing it from reaching the first conductivity type region. Furthermore, the horizontal movement speed of signal charges generated within the semiconductor substrate 11 is improved. This is a schematic cross-sectional view showing an example of the configuration of a photodetector according to the first embodiment of this disclosure.This is a schematic cross-sectional view illustrating another example of the configuration of a photodetector according to the first embodiment of the present disclosure.Figure 2 is a schematic diagram illustrating an example of the planar configuration of the p-type conductive region of the photodetector shown.Figure 2 is a schematic diagram illustrating another example of the planar configuration of the p-type conductive region of the photodetector shown in Figure 2.Figure 2 is a schematic diagram illustrating another example of the planar configuration of the p-type conductive region of the photodetector shown in Figure 2.Figure 2 is a schematic diagram illustrating an example of power supply connection to the n-type conductive regi