US Patent 10580823 Wafer level packaging method

A wafer level packaging method includes the following steps. A first wafer is bonded over a second wafer. A first grinding process on the first wafer is performed, to remove an upper chamfered edge of the first wafer and reduce a thickness of the first wafer. A trimming process is performed on the first wafer, to remove a lower chamfered edge of the first wafer to form a trimmed first wafer. A second grinding process is performed on the trimmed first wafer, to reduce a thickness of the trimmed first wafer.