Patent ID: 9698024
Date: 2017-07-04
CPC Classifications: G01R,H01L

Claim:
1. A method, comprising: providing a bonded wafer made up of a device wafer, a handle wafer, and an intermediate oxide layer bonding the device wafer to the handle wafer; forming a semiconductor device, which includes a source region and a drain region which are disposed in the device wafer, wherein the intermediate oxide layer separates both the semiconductor device and the device wafer from the handle wafer; and forming a recess in a lower surface of the handle wafer while leaving both the intermediate oxide layer and the device wafer entirely in place, thereby defining an un-recessed region and a recessed region of the handle wafer, wherein the un-recessed region has a first handle wafer thickness that is non-zero under the source region and the recessed region has a second handle wafer thickness that is non-zero under the drain region, the second handle wafer thickness being less than the first handle wafer thickness.