Patent ID: 8012857

Claim:
A method of forming a semiconductor die comprising: providing a semiconductor wafer having a semiconductor substrate, the semiconductor substrate having a first thickness, a top surface, a bottom surface, and a plurality of semiconductor die formed on the top surface of the semiconductor substrate and separated from each other by portions of the semiconductor wafer where singulation lines are to be formed; inverting the semiconductor wafer; reducing a thickness of an interior portion of the bottom surface of the semiconductor wafer to a second thickness that is less than the first thickness and leaving an outer rim of the semiconductor wafer with the first thickness wherein the outer rim is juxtaposed to a periphery of the semiconductor wafer, and wherein the interior portion is underlying the plurality of semiconductor die; forming a protective layer on the interior portion of the bottom surface of the semiconductor wafer wherein the protection layer is one of a metal or a metal compound or a metal-silicon compound; and using a dry etch to reduce the first thickness of the outer rim to a third thickness that is less than the first thickness wherein the protective layer protects the interior portion from the dry etch so that the second thickness remains substantially constant.