Patent ID: 8628998

Claim:
A method comprising: performing a grinding on a backside of a semiconductor substrate, wherein a remaining portion of the semiconductor substrate comprises a back surface, and wherein an image sensor is disposed on a front side of the semiconductor substrate; doping an impurity into a surface layer of the backside of the semiconductor substrate to form a doped layer; and performing a multi-cycle laser anneal on the doped layer, wherein the multi-cycle laser anneal comprises a multi-stage laser anneal or a multi-shot laser anneal, and wherein: the multi-stage laser anneal comprises: performing a first laser anneal on substantially an entirety of a wafer, wherein the wafer comprises the semiconductor substrate; and after the first laser anneal, performing a second laser anneal on the wafer; and the multi-shot laser anneal comprises: projecting a first laser shot on a region of the surface layer; and after the first laser shot and before projecting laser shots on other regions of the surface layer, projecting a second laser shot on the region.