A wafer cutting method includes forming a plurality of grooves by scanning a laser beam onto a front surface of a wafer, wherein the wafer comprises a plurality of layers, and the laser beam comprises at least two lights; polishing a rear surface of the wafer, mounting the wafer on a dicing tape, and cutting the wafer by expanding the dicing tape, wherein the forming the plurality of grooves includes forming at least two grooves by using the at least two lights, the at least two grooves having different widths on at least two layers, among the plurality of layers of the wafer.

A method for processing a wafer, which includes an insulating film on a surface thereof and forms a plurality of devices and streets thereon, by emitting laser beams along the streets to form grooves extending along the streets, includes a protective film forming step including forming a protective film on the surface of the wafer; a narrow groove forming step including emitting a first laser beam split in a widthwise direction within a width of the street on the wafer held on a chuck table into a plurality of beams, to form a plurality of narrow grooves extending along the street; a wide bottomed groove forming step including emitting a second laser beam having a predetermined width to eliminate the plurality of narrow grooves and form a bottomed groove having a predetermined width; and a protective film removing step including removing the protective film.