JP-7856981-B2 - Photodetectors, X-ray imaging sensors, and electronic equipment

Inventors

• 初井 宇記
• 河村 隆宏
• 唐仁原 裕樹
• 太田 和伸
• 白方 徹
• 岩田 晃
• 安藤 厚博

Assignees

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

Dates

Publication Date

20260512

Application Date

20220325

Priority Date

20210428

Claims (19)

1. A semiconductor substrate including a photoelectric conversion region, A first conductivity type region is provided at the interface of the first surface of the semiconductor substrate and connected to the first electrode, At the interface of the first surface, a second first conductivity type region is provided around the first first conductivity type 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, A conductive film provided above the first surface between at least the first conductive type region and the second first conductive type region , Embedded and formed within the semiconductor substrate, the second first conductivity region and the second conductivity region facing the third first conductivity region A new light-receiving element.
2. The photodetector according to claim 1, wherein the conductive film applies an electric field to the interface of the first surface between the first conductivity type region and the second conductivity type region.
3. The semiconductor substrate further comprises an insulating layer provided on the first surface side, The photodetector according to claim 1, wherein the conductive film is formed by at least one of a gate electrode provided on the first surface of the semiconductor substrate and a wiring layer provided within the insulating layer.
4. The photodetector according to claim 3, wherein the gate electrode and the wiring layer are electrically connected to each other.
5. The photodetector according to claim 3, wherein the gate electrode, the wiring layer, and the second first conductivity type region are electrically connected to each other.
6. The light-receiving element according to claim 3, wherein the wiring layer is formed continuously or intermittently from between the first first conductivity type region and the second first conductivity type region to above the third first conductivity type region.
7. The photodetector according to claim 3, wherein the gate electrode is formed using a semiconductor material and has a first region and a second region with different impurity concentrations.
8. The light-receiving element according to claim 7, wherein the first region has a lower impurity concentration than the second region and is located near the first conductivity type region.
9. The light-receiving element according to claim 7, wherein the first region has a lower impurity concentration than the second region and is located around the second region.
10. The light-receiving element according to claim 7, wherein the first region has a lower impurity concentration than the second region, and the first region and the second region are stacked in that order from the first surface side.
11. The photodetector according to claim 1, further comprising a fourth first conductivity region that is embedded and formed within the semiconductor substrate and faces the second conductivity region on the second surface side of the semiconductor substrate facing the first surface .
12. The photodetector according to claim 11, wherein the fourth first conductivity type region extends below the first first conductivity type region and is connected to the first first conductivity type region.
13. The photodetector according to claim 12 , wherein the fourth first conductivity type region has regions with different impurity concentrations.
14. The semiconductor substrate has a second conductivity type and further has a second conductivity type layer at the interface of the second surface facing the first surface. The photodetector according to claim 1 , wherein the second conductivity layer and the second conductivity region have a higher impurity concentration than the semiconductor substrate.
15. The photodetector according to claim 1, wherein the semiconductor substrate is made of an intrinsic semiconductor.
16. 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 the first surface of the semiconductor substrate and connected to the first electrode, At the interface of the first surface, a second first conductivity type region is provided around the first first conductivity type 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, A conductive film provided above the first surface between at least the first conductive type region and the second first conductive type region , Embedded and formed within the semiconductor substrate, the second first conductivity region and the second conductivity region facing the third first conductivity region X-ray imaging sensor.
17. 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 16 , wherein the semiconductor substrate has a depletion region in the pixel region and a neutral region in the peripheral region.
18. The X-ray imaging sensor according to claim 17, 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 the first surface of the semiconductor substrate and the second surface facing the first surface.
19. 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 the first surface of the semiconductor substrate and connected to the first electrode, At the interface of the first surface, a second first conductivity type region is provided around the first first conductivity type 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, A conductive film provided above the first surface between at least the first conductive type region and the second first conductive type region , Embedded and formed within the semiconductor substrate, the second first conductivity region and the second conductivity region facing the third first conductivity region Electronic devices equipped with these features.

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, photodetectors used in X-ray imaging sensors are required to have improved resistance to fluctuations in capacitance and electric field caused by X-ray irradiation. 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 a first surface of the semiconductor substrate and connected to a first electrode; a second conductivity type region provided at the interface of the first surface around the first conductivity type region and connected to a second electrode; a third conductivity type region provided at the interface of the first surface around the second conductivity type region and electrically floating; a conductive film provided above the first surface between at least the first conductivity type region and the second conductivity type region ; and a second conductivity type region embedded and formed within the semiconductor substrate and facing the second conductivity type region and the third conductivity type region . 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 a first surface of the semiconductor substrate and connected to a first electrode; a second conductivity type region provided at the interface of the first surface around the first conductivity type region and connected to a second electrode; a third conductivity type region provided at the interface of the first surface around the second conductivity type region and in an electrically floating state; and a conductive film provided above the first surface between at least the first conductivity type region and 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 first conductivity type region connected to a first electrode and a second first conductivity type region connected to a second electrode are provided at the interface of a first surface of a semiconductor substrate including a photoelectric conversion region, and a conductive film is provided above the first surface of the semiconductor substrate, at least between the first first conductivity type region and the second first conductivity type region. This suppresses the generation of fixed charges and interface states near the first surface between the first first conductivity type region and the second first conductivity type region during X-ray irradiation. This is a schematic cross-sectional view showing an example of the configuration of a photodetector according to the first embodiment of this disclosure.Figure 1 is a schematic plan view showing an example of the p-type conductive region and gate electrode pattern of the photodetector.Figure 1 is a schematic plan view illustrating another example of the pattern of the p-type conductive region of the photodetector shown in Figure 1.Figure