Single-photon avalanche diode, manufacturing method thereof, detector array and image sensor

Abstract

The invention discloses a single photon avalanche diode, a manufacturing method thereof, a detector array, and an image sensor. The back-illuminated single-photon avalanche diode is provided with a light trapping structure and a side wall reflecting wall. Incident light is scattered to all angles after being reflected, scattered and refracted by the light trapping structure, and the effective optical path of the light in the back-illuminated single-photon avalanche diode can be prolonged under the reflection action of the side wall reflection wall, so that the absorption efficiency of the light in the back-illuminated single-photon avalanche diode is improved. The invention relates to the manufacturing method of the back-illuminated single-photon avalanche diode, which realizes the manufacturing of the back-illuminated single-photon avalanche diode. Due to the fact that the photoelectric detector array and the image sensor comprise the back-illuminated single-photon avalanche diode, the light absorption efficiency of the photoelectric detector array and the image sensor is effectively improved.

Description

technical field [0001] The invention relates to the field of optoelectronics, in particular to a single-photon avalanche diode, a manufacturing method, a detector array, and an image sensor. Background technique [0002] Image sensors are widely used in various electronic devices, such as digital cameras, mobile phones, medical imaging equipment, security inspection equipment, distance measuring cameras and so on. With the continuous improvement of semiconductor technology for manufacturing image sensors, image sensors are further developing in the direction of low power consumption, miniaturization, and high integration. Image sensors typically consist of an array of photodetectors. A single photon avalanche diode (SPAD) is a type of photodetector that can be used in an image sensor. [0003] Single Photon Avalanche Diodes (SPADs) can be used in a variety of industrial and academic applications, depth detection (including lidar), medical sensing, machine vision, gesture r...

AI Technical Summary

Problems solved by technology

However, an overly thick device layer requires a corresponding increase in the area of ​​the SPAD, which reduces the number of units per unit area, and the processing of an overly thick device layer is difficult, the yield is low, and it is not easy to be compatible with the CMOS process, which increases the cost.

Additionally, using thick silicon increases the jitter time of the SPAD, and greater jitter time reduces the accuracy of range detection in LiDAR or other time-of-flight based applications

[0010] (2) Increase the incident rate of light by adding an anti-reflection film on the surface of the planar structure of the SPAD, but its anti-reflection effect will decrease with the increase of the incident angle, resulting in a decrease in the absorption efficiency of incident photons

[0011] (3) For the SPAD imaging array, the incident light angle received by the unit located at the edge of the array and converged by the lens is relatively large, which may lead to a decrease in absorption efficiency

However, there are many disadvantages in this method: 1) when the actual processing thickness of the silicon layer deviates slightly from the design, the resonance frequency will shift; 2) it is very sensitive to the wavelength of the incident light, and the absorption efficiency of light that deviates from the resonance frequency 3) When the temperature changes, the resonant frequency will also shift due to the slight change in the refractive index of the material; 4) It is very sensitive to the change of the incident light angle

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