Pixel structure and manufacturing method of cmos image sensor

Abstract

The invention discloses a pixel structure of a CMOS image sensor and a manufacturing method thereof. The pixel structure is located on a reading circuit or a processing circuit, and multi-layer P-type and N-type materials are simultaneously connected through a heavily doped contact structure. The material-doped film layers are connected together, and a thick depletion layer can be formed by using a small voltage, which is beneficial to light absorption; on the other hand, the multi-PN junction structure has a concave-convex surface structure by using metal pseudo-patterns, thereby expanding light absorption. At the same time, adding a thin metal reflective layer can reflect the transmitted light into the pixel absorbing layer, further improving light absorption. By using the pixel structure of the invention, the optical sensitivity and definition of the whole CMOS image sensor can be improved, and the performance and reliability of the chip can be improved.

Description

technical field [0001] The invention relates to the technical field of manufacturing semiconductor devices, 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 fabricating the photodiode 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. Make products with higher pixels. [0003] The traditional CMOS image sensor uses the method of front lighting, and the photodiode and the CMOS processing circuit structure are fabricated together on the silicon substrate and implemented at the same level, while the chip interconnection is fabricated on the CMOS processing circuit structure, and the ph...

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Problems solved by technology

[0005] However, in all existing technologies similar to the above-mentioned application, the pixel area of ​​the CMOS image sensor usually uses only one PN junction, so the width and thickness of the depletion layer are relatively small. If the width and thickness of the depletion layer are reduced by high voltage Larger, then high voltage will bring power consumption, process and other problems

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