WAFER PROCESSING METHODS

Abstract

A processing method for a wafer (W) having a chamfered portion (Wd) at an outer peripheral edge, comprising: an annular modified region (M) forming step of irradiating a laser beam (LB) having a transmission wavelength in the wafer (W) along the outer peripheral edge of the wafer (W) at a position on an inner side with a predetermined distance from the outer peripheral edge of the wafer (W) to form an annular modified region (M) having at least a depth from the front surface (Wa) of the wafer (W) to a finished thickness (L1); a modified region (M) forming step in an outer peripheral portion (W1) for irradiating a laser beam (LB) having a transmission wavelength in the wafer (W) at an outer peripheral portion (W1) of the wafer (W) to radially form a plurality of modified regions (M) having at least a depth from the front surface (Wa) of the wafer (W) to the finished thickness (L1) at the outer peripheral portion (W1) of the wafer (W); and a rear surface grinding step (Wb) for grinding the entire rear surface (Wb) of the wafer (W) to thin the wafer (W) to a finished thickness (L1) after the annular modified region (M) forming step and the outer peripheral portion (W1) modified region (M) forming step have been performed, wherein in the grinding step for a back surface (Wb), the grinding is continued while removing the outer peripheral portion (W1) of the wafer (W) from the wafer (W) from starting points given by the annular modified region (M) and the plurality of modified regions (M).

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