| 摘要 |
A laser beam machining method for a wafer, wherein an operation of irradiating the inside of a wafer with a laser beam L along each of planned dividing lines is repeated a plural number of times from a position proximate to a back-side surface of the wafer toward a face-side surface of the wafer so that a plurality of composite layers each including a denatured layer and a cracked layer extending from the denatured layer toward the face-side surface are formed stepwise at intervals (first laser beam irradiation step). Subsequently, each of some of non-cracked layers between the composite layers is irradiated with the laser beam L so as to extend the cracked layer of a given one of the composite layers and to cause the cracked layer to reach the denatured layer of the composite layer which is adjacent to the given one composite layer. The denatured layers and the cracked layers which are sufficient for enabling the wafer to be split are formed by a reduced number of laser beam irradiation operations.
|
