| abstract |
A method for efficiently processing an object to be processed by using an ultrashort pulse is provided. A laser beam processing method for a substrate or the like. The ultrashort pulse laser, which has a wavelength transparent to the workpiece, is focused, irradiated from the front side toward the back surface of the workpiece, and the beam waist position of the focused laser beam is focused on the workpiece. It is formed away from the back surface. Thereby, a condensing channel long in the light traveling direction is formed in the object from the beam waist formed by the self-focusing action by the laser light propagation in the object to be processed. The substance in the channel is decomposed by laser light and the substance is discharged from the back surface, thereby forming a cavity in the channel. When the laser beam is scanned while forming the cavity, a processed surface is formed, and thereafter the object to be processed can be cut with a weak bending stress. This method can also be applied to the case where two substrates are arranged facing each other, and can be used for dividing a glass substrate of a liquid crystal panel. [Selection] Figure 1 |