TWI787471B

An objective of the present invention is to prevent grinding water including ground fragments from infiltrating into a gap between neighboring chips even if a workpiece is formed in a finishing thickness. A method for machining a workpiece comprises: a surface protection step of covering an upper surface (Wa) of a workpiece with a surface protection member (1); a protection member heating step of hardening and contracting an adhesive material of the surface protection member (1); an alteration layer forming step of forming an alteration layer (M) in the workpiece (W); a back surface grinding step of grinding a back surface (Wb) of the workpiece to form the workpiece (W) in a finishing thickness of chips; and a protection member extending step of dividing the workpiece (W) into individual chips (C) and extending chip gaps (7). The adhesive material of the surface protection member (1) is hardened and contracted in the protection member heating step to form non-division area where chip division is not completed