CN-122002938-A - Light detecting element

Abstract

A light detection element includes a first semiconductor layer having a first main surface as a light incident surface and a second main surface opposite to the first main surface, an insulating layer formed on the second main surface, a quenching element located inside the insulating layer, and an opposite electrode layer located inside the insulating layer. The first semiconductor layer has a first semiconductor region of a first conductivity type and a second semiconductor region of a second conductivity type constituting an avalanche photodiode together with the first semiconductor region. The quenching element is electrically connected to the second semiconductor region. The opposite electrode layer is opposite to the second semiconductor region in a direction perpendicular to the first main surface. The counter electrode layer includes a peripheral region along an outer edge of the second semiconductor region, the peripheral region being a region located further inward than the outer edge of the second semiconductor region when viewed from a direction perpendicular to the first main surface.

Inventors

• Gang Tian Zhensheng
• SHI YOUTAI
• Earth house Okiayu Ryotaro
• Rock entry

Assignees

• 浜松光子学株式会社

Dates

Publication Date

20260508

Application Date

20251104

Priority Date

20241105

Claims (14)

1. 1. A light detecting element, wherein, The device is provided with: a first semiconductor layer having a first main surface as a light incident surface and a second main surface opposite to the first main surface; an insulating layer formed on the second main surface; a quenching resistor located inside the insulating layer, and An opposite electrode layer located inside the insulating layer, The first semiconductor layer has: A first semiconductor region of a first conductivity type, and A second semiconductor region of a second conductivity type located closer to the second main surface than the first semiconductor region, and forming an avalanche photodiode together with the first semiconductor region, The quenching resistor is electrically connected with the second semiconductor region, The opposite electrode layer is opposite to the second semiconductor region in a direction perpendicular to the first main surface, The counter electrode layer includes a peripheral region along an outer edge of the second semiconductor region, the peripheral region being a region located further inward than the outer edge of the second semiconductor region when viewed from a direction perpendicular to the first main surface.
2. 2. The light detecting element as in claim 1, wherein, The counter electrode layer is formed so as to reach the peripheral region from a central portion of the second semiconductor region when viewed from a direction perpendicular to the first main surface.
3. 3. The light detecting element according to claim 1 or 2, wherein, The counter electrode layer has a size of 50% or more of the size of the second semiconductor region when viewed from a direction perpendicular to the first main surface.
4. 4. The photodetection element according to any one of claims 1 to 3, wherein, The quenching resistor extends along the outer edge of the second semiconductor region and overlaps the outer edge of the second semiconductor region when viewed from a direction perpendicular to the first main surface.
5. 5. The photodetection element according to any one of claims 1 to 4, wherein, The counter electrode layer is located between the first semiconductor layer and the quenching resistor in a direction perpendicular to the first main surface.
6. 6. The photodetection element according to any one of claims 1 to 5, wherein, The outer edge of the counter electrode layer is located further inside than the outer edge of the second semiconductor region when viewed from a direction perpendicular to the first main surface.
7. 7. The photodetection element according to any one of claims 1 to 6, wherein, The quenching resistor extends along the outer edge of the second semiconductor region when viewed from a direction perpendicular to the first main surface, The outer edge of the counter electrode layer and the inner edge of the quenching resistor are separated from each other when viewed from a direction perpendicular to the first main surface, The width of the quenching resistor is larger than the distance from the outer edge of the counter electrode layer to the inner edge of the quenching resistor when viewed from the direction perpendicular to the first main surface.
8. 8. The photodetection element according to any one of claims 1 to 7, wherein, The quenching resistor has an overlapping portion positioned along an inner edge of the quenching resistor and overlapping the second semiconductor region, and a non-overlapping portion positioned closer to an outer edge of the quenching resistor than the overlapping portion and not overlapping the second semiconductor region when viewed from a direction perpendicular to the first main surface, The width of the overlapping portion is smaller than the width of the non-overlapping portion when viewed from a direction perpendicular to the first main surface.
9. 9. The photodetection element according to any one of claims 1 to 8, wherein, A trench including a rectangular frame-shaped frame portion extending so as to surround the avalanche photodiode when viewed from a direction perpendicular to the first main surface is formed in the first semiconductor layer, Each of the second semiconductor region and the quenching resistor is located inside the frame portion when viewed from a direction perpendicular to the first main surface, When viewed from a direction perpendicular to the first main surface, the outer edges of the second semiconductor region and the quenching resistor extend along the inner edge of the frame portion, and have corner portions formed so as to be convex toward corresponding corner portions among a plurality of corner portions provided in the inner edge of the frame portion, Each of the corner portion of the second semiconductor region and the corner portion of the quenching resistor has an R shape when viewed from a direction perpendicular to the first main surface.
10. 10. The photodetection element according to any one of claims 1 to 5, wherein, The outer edge of the counter electrode layer is located further outside than the outer edge of the second semiconductor region when viewed from a direction perpendicular to the first main surface.
11. 11. The photodetection element according to any one of claims 1 to 10, wherein, When viewed from a direction perpendicular to the first main surface, the outer edge of the counter electrode layer overlaps with or is located further outside than the inner edge of the quenching resistor.
12. 12. The photodetection element according to any one of claims 1 to 11, wherein, A trench including a frame-shaped frame portion extending so as to surround the avalanche photodiode when viewed from a direction perpendicular to the first main surface is formed in the first semiconductor layer, When viewed from a direction perpendicular to the first main surface, the outer edge of the quenching resistor overlaps with or is located further outside than the inner edge of the frame.
13. 13. The photodetection element according to any one of claims 1 to 12, wherein, A trench including a frame-shaped frame portion extending so as to surround the avalanche photodiode when viewed from a direction perpendicular to the first main surface is formed in the first semiconductor layer, Each of the second semiconductor region and the quenching resistor is located inside the frame portion when viewed from a direction perpendicular to the first main surface, When viewed from a direction perpendicular to the first main surface, a distance between an outer edge of the quenching resistor and an inner edge of the frame portion is smaller than a distance between an outer edge of the second semiconductor region and an inner edge of the quenching resistor.
14. 14. The light detecting element of claim 10, wherein, The distance between the inner edge of the quenching resistor and the outer edge of the opposite electrode layer is smaller than the distance between the outer edge of the second semiconductor region and the outer edge of the opposite electrode layer when viewed from a direction perpendicular to the first main surface.

Description

Light detecting element Technical Field An aspect of the present disclosure relates to a light detecting element. Background International publication No. 2018/174090 discloses an imaging device as an example of a light detection element, which includes a first semiconductor layer formed on a semiconductor substrate, a second semiconductor layer formed on the first semiconductor layer and having a conductivity type opposite to that of the first semiconductor layer, a third semiconductor layer formed on the second semiconductor layer and having a conductivity type identical to that of the second semiconductor layer, a pixel isolation portion defining a pixel region including the first semiconductor layer and the second semiconductor layer, a first electrode connected to the first semiconductor layer, and a second electrode connected to the second semiconductor layer. In such a light detection element, light incident on each pixel region is photoelectrically converted and detected as a current signal. For example, in the imaging device described in international publication No. 2018/174090, after charge carriers are generated (photoelectrically converted) in the third semiconductor layer by incidence of light, the charge carriers are multiplied in the first semiconductor layer and the second semiconductor layer after voltage is applied thereto via the first electrode and the second electrode. The multiplied charge carriers are detected as a current signal. Disclosure of Invention Problems to be solved by the invention In the above-described photodetection element, it is desirable to improve the detection accuracy. An object of an aspect of the present disclosure is to provide a light detection element capable of improving detection accuracy. Technical scheme for solving problems The light detection element according to one aspect of the present disclosure is [1] "a light detection element including a first semiconductor layer having a first main surface as a light incidence surface and a second main surface opposite to the first main surface, an insulating layer formed on the second main surface, a quenching resistor located inside the insulating layer, and a counter electrode layer located inside the insulating layer, the first semiconductor layer including a first semiconductor region of a first conductivity type, and a second semiconductor region of a second conductivity type located in the vicinity of the second main surface than the first semiconductor region, the second semiconductor region and the first semiconductor region together constituting an avalanche photodiode, the quenching resistor being electrically connected to the second semiconductor region, the counter electrode layer being opposite to the second semiconductor region in a direction perpendicular to the first main surface, the counter electrode layer including a peripheral region along an outer edge of the second semiconductor region, the peripheral region being located further inside than the outer edge region of the second semiconductor region when viewed from the first main surface. The light detection element includes a counter electrode layer facing the second semiconductor region in a direction perpendicular to the first main surface, and the counter electrode layer includes a peripheral region along an outer edge of the second semiconductor region, the peripheral region being located further inside than the outer edge of the second semiconductor region when viewed from the direction perpendicular to the first main surface. Thus, the counter electrode layer formed with an expansion so as to include a peripheral region along the outer edge of the second semiconductor region is opposed to the second semiconductor region. Therefore, light passing through the first semiconductor layer without photoelectric conversion is reflected toward the second semiconductor region in the opposite electrode layer. That is, the light having passed through the first semiconductor layer is again incident on the avalanche photodiode, and the sensitivity of the photodetector is improved. The photodetector includes a quenching resistor electrically connected to the second semiconductor region. This enables the light detection element to operate stably in the geiger mode. Therefore, according to the light detection element, the detection accuracy can be improved. The light detection element according to an aspect of the present disclosure may be the light detection element according to [2] "wherein the counter electrode layer is formed so as to reach the peripheral region from a central portion of the second semiconductor region when viewed from a direction perpendicular to the first main surface. In this case, the portion of the counter electrode layer facing the second semiconductor region is larger, and light passing through the first semiconductor layer can be reflected more reliably toward the second semiconductor region. Therefore, the detection accu