Method for fabricating CMOS image sensor

A method for fabricating a complementary metal oxide semiconductor image sensor, the method comprising:

• preparing a semiconductor substrate defining a photodiode region and a transistor region;
• sequentially forming an insulating layer and a conductive layer on an entire surface of the semiconductor substrate;
• forming a first photoresist pattern on the conductive layer;
• etching the conductive layer to a predetermined thickness using the first photoresist pattern as a mask;
• forming a second photoresist pattern on the etched conductive layer so as to cover the photodiode region;
• etching the conductive layer and the insulating layer using the second photoresist pattern as a mask, wherein a portion of the conductive layer and the insulating layer remain over the photodiode region;
• removing the first and second photoresist patterns;
• forming a third photoresist pattern exposing only the photodiode region;
• and
• removing the portion of the conductive layer and the insulating layer formed over the photodiode region using the third photoresist pattern as a mask to define a gate electrode and a gate insulating layer in the transistor region.