Patent ID: 8993922
Filing Date: 2015-03-31
Classification: B23K

Abstract:
1. A laser processing method for irradiating an object to be processed with a first laser beam while converging the first laser beam with a lens such that a converging point is positioned within the object, and forming a modified region within the object along a cutting line, the method comprising: a height acquiring step of irradiating the object with a second laser beam for measuring height of a main surface of the object in an optical axis direction of the lens while converging the second laser beam with the lens, and acquiring the height of the main surface along the cutting line by detecting reflected light reflected by the main surface in response to the irradiation of the object with the second laser beam; and a processing step of emitting the first laser beam and moving the lens and the object relative to each other in a perpendicular direction to the optical axis direction of the lens while adjusting a distance between the lens and the main surface according to the acquired height, so as to form the modified region along the cutting line in a predetermined depth relative to the main surface of the object; wherein the height acquiring step is performed at a first time interval while moving the lens and the object relative to each other at a first speed in the perpendicular direction to the optical axis direction of the lens; and wherein the processing step is performed at a second time interval shorter than the first time interval while moving the lens and the object relative to each other at a second speed faster than the first speed in the perpendicular direction to the optical axis direction of the lens.