Pixel structure of cmos image sensor and its manufacturing method

Abstract

The invention discloses a picture element structure of a CMOS (complementary metal oxide semiconductor) image sensor and a manufacturing method thereof. The structure comprises a light-sensitive element on a silicon substrate and a multi-layer structure for a CMOS device, wherein the multi-layer structure comprises a polysilicon layer, a contact hole layer, a metal interconnection layer, a through hole layer and an interconnection medium layer; the space above the light-sensitive element is surrounded by a light reflecting and shielding layer; and the light reflecting and shielding layer comprises a first polysilicon layer, a first contact hole layer and a first metal interconnection layer from bottom to top. The picture element structure disclosed by the invention enables a deep groove to be surrounded by an annular metal interconnection line, a through hole, a contact hole and polysilicon, enables the incident light on the deep groove to be basically completely reflected, avoids the occurrence of optical crosstalk, effectively improves the optical resolution and sensitivity of a picture element, and increases the performance and reliability of a chip.

Description

technical field [0001] The invention relates to the technical field of CMOS image sensors, in particular to a pixel structure of a CMOS image sensor and a manufacturing method thereof. 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 photosensitive element and the CMOS processing circuit together on the silicon substrate, the cost is greatly reduced on the basis of ensuring 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 photosensitive element and the CMOS processing circuit are implemented together on the silicon substrate at the same level, while the chip interconnection is fabricated on the CMOS processing circuit, and the photosensitive element ...

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 photosensitive element and fill it with a light-transmitting material to enhance its light absorption.

[0004] However, as the pixel size decreases, the distance between adjacent pixels also decreases sharply. When light is incident, the light will pass through the area between adjacent pixels through refraction and multiple reflections to reach the side One pixel, which will cause optical crosstalk between pixels, resulting in poor image signal sensitivity, resolution and clarity of the pixel, and poor chip performance

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