| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide a pattern of laser light irradiation, with which a wafer can be easily and securely divided without lowering processing efficiency. <P>SOLUTION: The operation to irradiate the inside of the wafer with a laser light beam L along division presumptive lines is performed several times from a position close to the side of a reverse surface 1b of the wafer toward the side of a top surface 1a to form a plurality of composite layers 52 each comprising an alteration layer 50 and a crack layer 51 extending from the alteration layer 50 toward the top surface in steps at intervals (first layer light beam irradiation stage). Then non-crack layers 53 between the plurality of composite layers 52 are irradiated with the laser light beam L and thus the crack layers 51 are extended to reach adjacent alteration layers 50. The alteration layers 50 and crack layers (crack layers 51 plus extended crack layers 54) which are sufficient for division are formed by performing a small number of laser light beam irradiating operations. <P>COPYRIGHT: (C)2009,JPO&INPIT</p> |
