Patent ID: 8673743
Filing Date: 2014-03-18
Classification: B23K,B28D,H01L

Abstract:
1. A wafer dividing method of dividing a wafer into a plurality of devices formed on a front side of said wafer so as to be partitioned by a plurality of division lines, said wafer dividing method comprising: an etching mask preparing step of preparing an etching mask so that said etching mask fully covers the back side of said wafer; an etching mask removing step of partially removing said etching mask along said division lines to partially expose the back side of said wafer along said division lines; a modified layer forming step of applying a laser beam having a transmission wavelength to said wafer in a condition where the focal point of said laser beam is set inside said wafer at the positions corresponding to said division lines, thereby forming a plurality of modified layers inside said wafer along said division lines, each of said modified layers having a thickness ranging from the vicinity of the front side of said wafer to the vicinity of a back side of said wafer; and an etching step of supplying an etching liquid to said wafer to erode said modified layers and thereby form a groove corresponding to each of said modified layers, whereby said grooves extend from the front side of the wafer to the back side of the wafer, thereby dividing said wafer into said individual devices, wherein said modified layer forming step is performed by applying said laser beam to an exposed part of the back side of said wafer.