CMOS image sensor and method for manufacturing the same

A method of fabricating a CMOS image sensor, comprising:

• forming an insulating layer on a first conductive type semiconductor substrate;
• defining a gate area by selectively removing the insulating layer such that a predetermined portion of a surface of the semiconductor substrate is exposed;
• forming a gate insulating layer on the surface of the exposed semiconductor substrate;
• forming a conductive layer on an entire surface of the semiconductor substrate and planarizing the conductive layer by adopting a top surface of the insulating layer as an end point, thereby forming a gate electrode on the gate insulating layer;
• reducing a thickness of the insulating layer at both sides of the gate electrode;
• forming an insulating layer sidewall on the insulating layer at both sides of the gate electrode;
• forming a low-density second conductive type diffusion area on a photodiode area at a first side of the gate electrode;
• and
• forming a high-density second conductive type diffusion area on a transistor area at a second side of the gate electrode.