WAFER PROCESSING METHOD INCLUDING APPLYING A POLYESTER SHEET TO A WAFER

A wafer processing method includes a polyester sheet providing step of positioning a wafer (1) in an inside opening (7a) of a ring frame (7) and providing a polyester sheet (9) on a back side (1b) or a front side (1a) of the wafer (1) and on a back side (7c) of the ring frame (7), a uniting step of heating the polyester sheet (9) as applying a pressure to the polyester sheet (9) to thereby unite the wafer (1) and the ring frame (7) through the polyester sheet (9) by thermocompression bonding, a dividing step of applying a laser beam (16) to the wafer (1) to form modified layers (3a) in the wafer (1), thereby dividing the wafer (1) into individual device chips (1c), and a pickup step of blowing out air (34a) to push up each device chip (1c) and picking up each device chip (1c) from the polyester sheet (9).