Method of making cmos image sensor-hybrid silicide

A method for manufacturing a CMOS image sensor, the method comprising:

• providing a semiconductor substrate;
• forming at least one isolation region between a periphery region of the substrate and a photo-sensing region of the substrate;
• forming a first well in the periphery region and a second well in the photo-sensing region of the substrate;
• forming a third well in the photo-sensing region of the substrate, the third well being associated with a photodiode;
• depositing a gate oxide layer on a surface of the substrate;
• depositing a polysilicon layer over the gate oxide layer;
• depositing a first metal layer over the polysilicon layer;
• etching the polysilicon layer and first metal layer to form an least one gate in the photo-sensing region and at least one gate in the periphery region;
• forming spacers for each of the at least one gate in the photo sensing region and the at least one gate in the periphery region;
• implanting a first plurality of ions to form at least two doped regions in the first well;
• implanting a second plurality of ions to form a doped region in the second well;
• depositing a silicide block layer over the photo-sensing region of the substrate;
• depositing a second metal layer at least over the periphery region after deposition of the silicide block layer;
• exposing the substrate to a thermal environment to simultaneously form silicide in the at least two doped regions in the first well and the at least one gate in the photo-sensing region;
• and
• etching after the exposing to the thermal environment to remove the second metal layer.