Cmos image sensor and method for forming the same

Abstract

A CMOS image sensor and a method for forming the same are provided. According to the method, a gate insulating layer and a doped polysilicon layer which are sequentially stacked on a substrate are patterned to form a transfer gate and a reset gate set apart from each other. A floating diffusion layer between the transfer gate and the reset gate, a light receiving element at a side of the transfer gate away from and opposite to the floating diffusion layer and a source/drain region at a side of the reset gate away from and opposite to the floating diffusion layer are formed. An insulation layer and a mold layer are sequentially formed on an entire surface of the substrate, and the mold layer is planarized until the insulation layer is exposed. The exposed insulation layer is removed to further expose an upper surface of the gates. A selective silicidation process is carried out using a metal gate layer to form a metal gate silicide on the exposed gate. The sequential steps in the selective silicidation process alleviate the metal contamination prevalent in various wet cleaning processes that may increase the malfunction of CMOS image sensors.