Patent ID: 7919395

Claim:
A wafer separating method for separating a wafer along a plurality of streets to obtain a plurality of individual devices, said wafer being composed of a substrate and a laminated member formed on said substrate, said laminated member being composed of an insulating film and a functional film laminated on said insulating film, said wafer separating method comprising: a laminated member removing step for partially removing said laminated member along said streets by applying a laser beam to said wafer along said streets; and a cutting step for cutting said substrate along said streets after said laminated member removing step; said laminated member removing step including a first laser processing step for applying a first laser beam along two parallel lines spaced apart from each other in each street, said first laser beam being capable of passing through said laminated member and having an absorption wavelength corresponding to said substrate, thereby heating said substrate to generate two cracks in said laminated member by thermal shock so that said two cracks extend along said two parallel lines in each street and across a plurality of intersecting streets, without exposing the substrate, and a second laser processing step for applying a second laser beam to a region between said two cracks in said laminated member, said second laser beam having an energy intensity higher than that of said first laser beam, thereby removing said region between said two cracks in said laminated member to expose said substrate along each street, wherein the energy intensity of said first laser beam is set to 7 to 8 J/cm 2 , and the energy intensity of said second laser beam is set to 14 to 16 J/cm 2 ; said first laser beam along said two parallel lines is focused near the upper surface of said substrate above both edges of each street; and said second laser beam is focused near the upper surface of said substrate above a center of each street.