Patent ID: 8173518

Claim:
A method of fabricating a semiconductor device, comprising: providing a device substrate having a front side, a back side, and a first edge portion; forming a material layer over at least a portion of the front side of the device substrate; performing a first trimming process to remove at least a part of the first edge portion; removing the material layer; forming a buffer layer on the front side of the device substrate; bonding the front side of the device substrate to a carrier substrate, wherein the buffer layer is bonded between the device substrate and the carrier substrate; after the bonding, thinning the device substrate from the back side; and after the thinning, performing a second trimming process to remove a second edge portion of the thinned device substrate as well as a portion of the carrier substrate, wherein the second trimming process removes a portion of the buffer layer and a portion of the carrier substrate aligned with the second edge portion of the thinned device substrate.