Image sensing unit and manufacturing method thereof, and image sensor

Abstract

The invention discloses an image sensing unit and a manufacturing method thereof, and an image sensor. The image sensing unit is provided with light trapping structures. The incident light is dispersed to various angles after being reflected, scattered and refracted by the light trapping structure, which, with the addition of the reflection function of a sidewall reflecting wall, can extend the effective optical path of the light in the image sensing unit. Therefore, the absorption efficiency of light in the image sensing unit can be improved without increasing the thickness of the device. Inaddition, a manufacturing method of the image sensing unit is disclosed, which realizes the manufacture of the image sensing unit. The image sensing unit has a first light trapping structure and a second light trapping structure, which can improve the light absorption efficiency of the image sensing unit.

Description

Technical field [0001] The invention relates to the field of optoelectronics, in particular to an image sensor unit, a manufacturing method thereof, 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, rangefinder cameras and so on. With the continuous advancement of semiconductor technology for manufacturing image sensors, image sensors are further developing towards low power consumption, miniaturization, and high integration. The image sensor is usually composed of a photodetector array. The image sensor unit can be a traditional CMOS image sensing unit (CIS) or a single photon avalanche diode (SPAD), both of which can be integrated and manufactured through a CMOS process. In addition, the image sensor includes a front-illuminated image sensor and a back-illuminated image sensor. The cross-sectional structure diagram of t...

AI Technical Summary

Problems solved by technology

However, an overly thick device layer requires a corresponding increase in the area of ​​the image sensor, 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.

[0006] (2) Increase the incident rate of light by adding an anti-reflection film on the surface of the image sensor's planar structure, 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

[0007] (3) For the image sensing unit array, the units located at the edge of the array receive a larger angle of incident light converged by the lens, which may lead to a reduction 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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