Patent ID: 7531374

Claim:
A CMOS image sensor (CIS) process, comprising: providing a semiconductor substrate; sequentially forming a gate dielectric layer, a gate material layer and a thickening layer on the substrate, the thickening layer comprising at least a hard mask layer; defining the thickening layer to form a transfer-gate pattern; forming a photoresist pattern over a portion of the gate material layer that is predetermined for forming a reset gate; using the transfer-gate pattern and the photoresist pattern as etching masks to pattern the gate material layer and form a transfer gate and a reset gate; and performing ion implantation to form a PN diode in the substrate with the transfer-gate pattern and the transfer gate as a mask, wherein a thickness of the transfer gate alone is insufficient to prevent ions from being implanted into the substrate under the transfer gate but the transfer gate and the transfer-gate pattern in combination prevent ions from being implanted into the substrate under the transfer gate.