CN-122002919-A - Photodetector and method for manufacturing photodetector

CN122002919ACN 122002919 ACN122002919 ACN 122002919ACN-122002919-A

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 first main surface, a second semiconductor layer formed on the first main surface via the insulating layer, and a quenching element on the second main surface side. The first semiconductor layer has a first semiconductor region of a first conductivity type, a second semiconductor region of a second conductivity type which constitutes an avalanche photodiode together with the first semiconductor region, and a third semiconductor region of the first conductivity type which is located closer to the first main surface than the first semiconductor region and has an impurity concentration higher than that of the first semiconductor region. The quenching element is electrically connected to the second semiconductor region. A textured structure having a concave-convex shape is formed on the surface of the second semiconductor layer.

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 (10)

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 first main surface; a second semiconductor layer formed on the first main surface via the insulating layer, and A quenching element located on the second main surface side with respect to the first semiconductor layer, The first semiconductor layer has: a first semiconductor region of a first conductivity type; 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, and A third semiconductor region of the first conductivity type, which is located closer to the first main surface than the first semiconductor region, has an impurity concentration higher than that of the first semiconductor region, The quenching element is electrically connected to the second semiconductor region, A textured structure having a concave-convex shape is formed on the surface of the second semiconductor layer.
2. The light detecting element as in claim 1, wherein, The texture feature is formed in a surface of the second semiconductor layer on an opposite side from the insulating layer.
3. The light detecting element according to claim 2, wherein, The device further comprises: A resin layer formed on the second semiconductor layer so as to cover the texture structure, and And a lens portion disposed on the texture structure via the resin layer.
4. The photodetection element according to any one of claims 1 to 3, wherein, The first semiconductor layer has: a plurality of first semiconductor regions respectively serving as the first semiconductor regions, and A plurality of second semiconductor regions respectively serving as the second semiconductor regions, The plurality of first semiconductor regions and the plurality of second semiconductor regions constitute a plurality of avalanche photodiodes as the avalanche photodiodes respectively, A trench is formed in the first semiconductor layer so as to extend so as to separate the plurality of avalanche photodiodes from each other when viewed from a direction perpendicular to the first main surface, The groove is formed so as to reach the second main surface from the first main surface.
5. The light detecting element as in claim 4, wherein, Also provided are a plurality of lens sections disposed on the second semiconductor layer, Each of the plurality of lens portions is arranged so as to overlap with a corresponding avalanche photodiode of the plurality of avalanche photodiodes in a direction perpendicular to the first main surface, When viewed from a direction perpendicular to the first main surface, the outer edges of the plurality of lens portions overlap the grooves.
6. The light detecting element as in claim 4, wherein, Further provided with a metal wiring disposed on the first main surface so as to extend along the trench, The side surface of the metal wiring is in contact with the insulating layer and the second semiconductor layer.
7. The light detecting element of claim 6, wherein, Also provided is a resin layer formed on the second semiconductor layer, The surface of the metal wiring on the opposite side of the first main surface is in contact with the resin layer.
8. The light detecting element according to claim 6 or 7, wherein, The metal wiring is formed so as to cover the entire trench when viewed from a direction perpendicular to the first main surface, Each of the plurality of avalanche photodiodes is surrounded by the metal wiring when viewed from a direction perpendicular to the first main surface.
9. A method for manufacturing a light detecting element, wherein, A method for manufacturing a photodetector according to any one of claims 1 to 8, Comprising the following steps: A step of forming a second semiconductor layer by polishing a layer corresponding to the second semiconductor layer formed on the insulating layer, and And forming the texture structure on the surface of the second semiconductor layer.
10. The method for manufacturing a light detecting element according to claim 9, wherein, In the step of forming the texture structure, the texture structure is formed by etching a surface of the second semiconductor layer on the opposite side from the insulating layer.

Description

Photodetector and method for manufacturing photodetector Technical Field An aspect of the present disclosure relates to a light detection element and a method of manufacturing the light detection 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, even if light enters the semiconductor layer, the generation of charge carriers in the semiconductor layer may be insufficient, and as a result, the light entering the photodetection element may not be detected with a desired accuracy. An object of one aspect of the present disclosure is to provide a light detection element capable of improving detection accuracy, and a method for manufacturing such a light detection element. 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 first main surface, a second semiconductor layer formed on the first main surface via the insulating layer, and a quenching element located on the second main surface side with respect to the first semiconductor layer, the first semiconductor layer including a first semiconductor region of a first conductivity type, a second semiconductor region of a second conductivity type located in the vicinity of the second main surface with respect to the first semiconductor region, the second semiconductor region forming an avalanche photodiode together with the first semiconductor region, and the third semiconductor region of the first conductivity type located in the vicinity of the first main surface with respect to the first semiconductor region, the quenching element and the second semiconductor region having a textured structure with a concave-convex shape formed on a surface of the second semiconductor region. In the light detection element, the first semiconductor layer has a first main surface as a light incident surface, and a textured structure having a concave-convex shape is formed on a surface of the second semiconductor layer formed on the first main surface via the insulating layer. Thus, the optical path of the light incident on the first semiconductor layer is changed so as to be inclined with respect to the direction perpendicular to the first main surface by the concave-convex shape of the texture structure. As a result, the optical path length of the light passing through the first semiconductor region becomes longer, and more charge carriers are generated in the first semiconductor region. The generated charge carriers are further multiplied by an avalanche photodiode constituted by the first semiconductor region and the second semiconductor region, and detected as a current signal. Thus, the sensitivity of the light detecting element (PDE: photon Detection Efficiency, photon detection efficiency) is improved. In the case where the third semiconductor region is formed with a texture structure, the first semiconductor layer is damaged, and the detection accuracy may be lowered by noise signals due to the damage. In addition, in the case where the insulating layer is formed with a texture structure, crosstalk occurs through the insulating layer, and the detection accuracy may be lowered. In contrast, in the above-described light detection element, since the texture structure is formed on the surface of the second semiconductor layer, degradation in detection accuracy due to such damage and cros