Self-aligned photodiode for CMOS image sensor and method of making

摘要

A method for forming a photodiode that is self-aligned to a transfer gate while being compatible with a metal silicide process is disclosed. The method comprises forming a gate stack of gate oxide, polysilicon, and a sacrificial/disposable cap insulator over the polysilicon. The insulator may be a combination of silicon oxynitride and silicon dioxide. After formation of the photodiode, the cap insulator layer is removed.