Shanghai Huali Microelectronics Corporation

Cuiyu Mei

Lu Wang

The present application discloses a method for preparing a pixel cell of a CMOS image sensor. Process optimization and adjustment for multiple times of ion implantation in a pixel area of the CMOS image sensor are carried out. That is, photodiode N-type ion implantation is performed before formation of a polysilicon gate of each MOS transistor of a CMOS pixel readout circuit, a photoresist open area is enlarged by means of a photoresist dry etching descum process such that an N-type ion implantation area is enlarged, and second photodiode N-type ion implantation is performed on the basis of the photoresist dry etching descum process, so as to achieve two times of photodiode N-type ion implantation using the same mask, with different depths and different pattern sizes, thereby forming an N-type area of the photodiode that tapers to the bottom, saving a mask layer, and reducing photolithography steps.

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Shanghai, China

Cuiyu Mei