Patent ID: 9349646
Filing Date: 2016-05-24
CPC Classification: B23K,H01L

Claim Text:
1. A wafer processing method for dividing a wafer along a plurality of division lines to obtain a plurality of individual chips, wherein said wafer includes an upper surface and a lower surface, said wafer processing method comprising: a filament forming step of applying a pulsed laser beam having a transmission wavelength to said wafer along each division line in a condition where the focal point of said pulsed laser beam is set inside said wafer in a subject area to be divided, thereby forming a plurality of amorphous filaments inside said wafer along each division line, wherein said amorphous filaments are each composed of a hole and an amorphous layer formed around said hole, wherein the filament forming step is performed under processing conditions configured to result in the holes of said amorphous filaments being separated from each other at predetermined intervals; and an etching step of etching said amorphous filaments formed inside said wafer along each division line by using an etching agent to thereby divide said wafer into said individual chips along said division lines, wherein said pulsed laser beam to be applied in said filament forming step is focused by a focusing lens, and the numerical aperture of said focusing lens is set in the range of 0.1 to 0.3, and wherein each of the holes of the amorphous filaments and the amorphous layer extend from the upper surface of the wafer to the lower surface of the wafer, thereby extending completely through the wafer.