A cmos image sensor optical enhancement structure and preparation method

Abstract

The invention discloses an optical enhancement structure of a CMOS (complementary metal oxide semiconductor transistor) image sensor and a method for manufacturing the optical enhancement structure. The structure comprises a silicon substrate, a photosensitive element and a standard CMOS multilayer structure. The photosensitive element and the standard CMOS multilayer structure are arranged on the silicon substrate, and a deep groove which forms light transmission space is arranged on the photosensitive element and is surrounded by metal reflecting layers, so that incident light of the metal reflecting layers can be reflected. The optical enhancement structure and the method have the advantages that each thin metal reflecting layer is formed on the corresponding side wall of the deep groove formed on the photosensitive element, so that the incident light is completely reflected onto the photosensitive element, optical crosstalk among adjacent pixels is shielded, the intensity of incident light on the photosensitive element is enhanced, and the optical sensitivity of the CMOS image sensor and the performance and the reliability of a chip are improved.

Description

technical field [0001] The invention relates to the technical field of CMOS image sensors, in particular to an optical enhancement structure and a preparation method of a CMOS image sensor. Background technique [0002] The CMOS image sensor has been developed rapidly due to its compatibility with the CMOS process. Compared with the CCD process, its process is completely compatible with the CMOS process. By making the photodiode and the CMOS processing circuit together on the silicon substrate, the cost is greatly reduced on the basis of guaranteed performance, and the integration level can be greatly improved. , to manufacture products with higher pixels. [0003] The traditional CMOS image sensor uses the method of front lighting, and the photodiode and the CMOS processing circuit are made together on the silicon substrate and implemented at the same level, while the chip interconnection is fabricated on the CMOS processing circuit, and the photodiode is used for light tr...

AI Technical Summary

Problems solved by technology

However, the light transmission of conventional semiconductor materials is poor, so it is necessary to remove all the dielectric layer above the photodiode and fill it with a light-transmitting material to enhance its light absorption.

[0004] At the same time, as the size of the pixel decreases, the distance between adjacent pixels also decreases sharply, and the incident light may enter adjacent pixels through refraction and multiple reflections, resulting in optical crosstalk. , it will cause the resolution of the pixel to decrease and the performance of the chip to deteriorate

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