CMOS image sensor and manufacturing method thereof

A method for manufacturing a CMOS image sensor, comprising:

• forming a dummy gate stack with a gate insulation layer and a dummy gate electrode layer on a semiconductor substrate;
• forming a gate spacer layer on at least a sidewall of the dummy gate stack;
• forming a source/drain region on the semiconductor substrate by an ion implantation process using the dummy gate stack and the gate spacer layer as an implantation mask;
• removing the dummy gate stack to expose a partial surface of the semiconductor substrate;
• forming an insulation layer with a high dielectric constant on the exposed surface of the semiconductor substrate;
• forming a gate electrode layer on the insulation layer with a high dielectric constant;
• sequentially forming a liner layer and a dummy pre-metal dielectric layer on the entire surface of the semiconductor substrate having the gate electrode layer thereon;
• partially removing the dummy pre-metal dielectric layer and the liner layer to expose a surface of the gate electrode by a planarization process;
• sequentially removing the dummy pre-metal dielectric layer and the liner layer in a peripheral circuit region by using a mask layer pattern to cover a pixel region;
• forming a silicide layer on the gate electrode layer in the pixel region and on the gate electrode layer and the source/drain region in the peripheral circuit region by a silicidation process;
• and
• removing the dummy pre-metal dielectric layer and the liner layer remaining in the pixel region.