Laser processing method and laser processing device

Abstract

In the laser processing method, the cross-sectional form of laser light L at a converging point P is such that the maximum length in a direction perpendicular to a line to cut 5 is shorter than the maximum length in a direction parallel to the line to cut 5. Therefore, when seen from the incident direction of the laser light L, a modified region 7 formed within a silicon wafer 11 has such a shape that the maximum length in the direction perpendicular to the line to cut 5 is shorter than the maximum length in the direction parallel to the line to cut 5. Forming the modified region 7 having such a shape within the object 1 can restrain twist hackles from occurring on cut surfaces when cutting the object 1 from the modified region 7 acting as a cutting start point, thereby making it possible to improve the flatness of the cut surfaces.

Dependencies are inferred from the claim text.