Image sensor and forming method thereof

Abstract

Disclosed are an image sensor and a forming method thereof. The method comprises the steps of providing a semiconductor substrate, wherein the semiconductor substrate comprises an image sensor region;forming a shallow trench isolation groove in the image sensor region; forming a covering layer on the side wall and the bottom of the shallow trench isolation groove, wherein the covering layer material is an amorphous material; after the covering layer is formed, forming an isolation layer in the shallow groove isolation groove. By virtue of the covering layer, the surface roughness of the semiconductor substrate exposed out of the shallow trench isolation trench is lowered, the surface state of the isolation layer and the semiconductor substrate is improved, dark current is reduced, and theperformance of the image sensor is improved.

Description

technical field [0001] The invention relates to the field of semiconductor manufacturing, in particular to an image sensor and a forming method thereof. Background technique [0002] An image sensor is a semiconductor device that converts light signals into electrical signals. Image sensors are classified into complementary metal oxide (CMOS) image sensors and charge coupled device (CCD) image sensors. CMOS image sensor has the advantages of simple process, easy integration of other devices, small size, light weight, low power consumption and low cost. Therefore, with the development of image sensing technology, CMOS image sensors are increasingly used in various electronic products instead of CCD image sensors. At present, CMOS image sensors have been widely used in still digital cameras, digital video cameras, medical imaging devices, and automotive imaging devices. [0003] The pixel unit of the CMOS image sensor is the core device for the image sensor to realize light...

AI Technical Summary

Problems solved by technology

The most commonly used pixel unit is to include a photodiode PD. In order to avoid electrical crosstalk between PDs, shallow trench isolation STI is formed between PDs. However, when making STI shallow trench isolation, due to the oxidation of the silicon substrate and the STI filling material There are defects in the silicon interface, which can generate dark current

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