US Patent 9393669 Systems and methods of processing substrates

Some embodiments provide methods of processing wafers comprising: positioning a stacked wafer into a position to be ground, wherein the stacked wafer comprises a first wafer secured with a carrier-wafer, wherein the first wafer is secured with the carrier-wafer such that a surface of the first wafer is exposed to be ground; initiating a grinding of the first wafer while supported by the carrier-wafer; activating one or more sensors relative to the first wafer while grinding the first wafer; determining, while grinding the first wafer, a thickness of the first wafer separate from a thickness of the carrier-wafer as a function of data from the one or more sensors; determining whether the determined thickness of the first wafer has a predefined relationship with a first thickness threshold; and halting the wafer grinding when the thickness of the first wafer has the predefined relationship with the first thickness threshold.