CN-114730708-B - Laser processing device and laser processing method

CN114730708BCN 114730708 BCN114730708 BCN 114730708BCN-114730708-B

Abstract

The laser processing device of the present invention is a laser processing device for performing laser processing of an object made of a birefringent material, and includes a light source for outputting laser light, a spatial light modulator for modulating the laser light output from the light source, a condensing lens for condensing the laser light toward the object, and a polarization component control unit functioning as the spatial light modulator for controlling a polarization component of the laser light so as to condense the object at a point in a Z direction (optical axis direction).

Inventors

Wani Kotaro
IZAKI YASUHIRO

Assignees

浜松光子学株式会社

Dates

Publication Date: 20260508
Application Date: 20201120
Priority Date: 20191127

Claims (3)

1. A laser processing apparatus, wherein, A laser processing apparatus for irradiating a semiconductor object made of a birefringent material with laser light and performing laser processing of the semiconductor object, The laser processing device is provided with: a laser output unit that outputs the laser; a reflective liquid crystal spatial light modulator that modulates the laser light output from the laser light output unit; a condensing lens for condensing the laser light toward the semiconductor object, and A polarization component control unit that controls the polarization component of the laser beam so that the semiconductor object is focused at a point in the optical axis direction, The laser output section outputs the laser light as linearly polarized light, The polarized light component control part unifies the polarized light component of the laser to one of P polarized light and S polarized light, The polarized light component control part comprises a slit part for blocking the P polarized light or the S polarized light of the laser, The slit portion is a slit pattern set as a modulation pattern of the spatial light modulator.
2. The laser processing apparatus according to claim 1, wherein, The birefringent material is a uniaxial crystalline material with a plane orientation 001.
3. A laser processing method, wherein, Is a laser processing method for irradiating a semiconductor object made of a birefringent material with laser light and performing laser processing of the semiconductor object, The laser processing method comprises the following steps: A step of placing the semiconductor object on a stage; setting a polarization component control unit for controlling a polarization component of the laser beam so as to be focused on a point in an optical axis direction of the semiconductor object, and A step of outputting the laser beam, In the step of setting the polarization component control unit, a slit pattern for blocking the P-polarization or S-polarization of the laser light is set as a modulation pattern of a reflective liquid crystal spatial light modulator for modulating the laser light.

Description

Laser processing device and laser processing method Technical Field One embodiment of the present invention relates to a laser processing apparatus and a laser processing method. Background A processing method is known in which a semiconductor object such as a semiconductor ingot (ingot) is irradiated with laser light to form a modified region in the semiconductor object and a crack extending from the modified region is developed to cut a semiconductor member such as a semiconductor wafer from the semiconductor object (for example, refer to patent documents 1 and 2). Prior art literature Patent literature Patent document 1 Japanese patent application laid-open No. 2017-183600 Patent document 2 Japanese patent application laid-open No. 2017-057103 Disclosure of Invention Problems to be solved by the invention Here, for example, in the case of focusing laser light on a semiconductor object made of a birefringent material such as a gallium nitride (GaN) ingot, the refractive indices of the P-polarized light component and the S-polarized light component of the incident light are different from each other. In addition, these incident lights are divided into ordinary lights and extraordinary lights, wherein the extraordinary lights do not follow Snell's law (Snell's law) and the lights propagate at a refraction angle different from the ordinary lights. For these reasons, the P-polarized light component and the S-polarized light component are condensed at different positions from each other in the depth direction of the semiconductor object. As described above, since the converging point is branched in the depth direction, a plurality of scratches are unintentionally formed in the semiconductor object, and improper cracks are generated. Because of this, the processing quality of the slice (slicing) or the like may be degraded. In view of the above circumstances, an object of the present invention is to improve the quality of laser processing of a semiconductor object made of a birefringent material. Means for solving the problems A laser processing apparatus according to an aspect of the present invention is a laser processing apparatus that irradiates a semiconductor object made of a birefringent material with laser light and performs laser processing of the semiconductor object, and includes a laser light output unit that outputs the laser light, a spatial light modulator that modulates the laser light output from the laser light output unit, a condensing lens that condenses the laser light toward the semiconductor object, and a polarization component control unit that controls a polarization component of the laser light so that the semiconductor object is condensed at a point in an optical axis direction. In the laser processing apparatus according to one embodiment of the present invention, the laser beam output from the laser beam output unit is modulated by the spatial light modulator, and is condensed on the semiconductor object by the condensing lens. In the laser processing apparatus, the polarization component of the laser beam is controlled by the polarization component control unit so as to be focused on one point of the semiconductor object. In general, when a laser beam is focused on a semiconductor object made of a birefringent material, the refractive indices of the P-polarized light component and the S-polarized light component of incident light are different from each other. In addition, these incident lights are divided into ordinary lights and extraordinary lights, wherein the extraordinary lights do not follow the snell's law and the lights propagate at a refraction angle different from the ordinary lights. For these reasons, the P-polarized light component and the S-polarized light component are condensed at different positions (the condensed point becomes two points) in the depth direction of the semiconductor object. As described above, a plurality of scratches are formed unintentionally in the semiconductor object, and improper cracks are generated in the semiconductor object, and there is a possibility that the processing quality such as dicing may be degraded. In this regard, as in the laser processing apparatus according to one embodiment of the present invention, the polarization component of the laser beam is controlled by the polarization component control unit so as to be focused on one point of the semiconductor object, and the focused point is only one point, and since only one mark is formed on the semiconductor object, it is possible to suppress occurrence of unexpected (improper) cracks on the semiconductor object. Thus, reduction in processing quality such as slicing can be suppressed. As described above, according to the laser processing apparatus of one embodiment of the present invention, the quality of laser processing of a semiconductor object made of a birefringent material can be improved. In the laser processing apparatus, the laser output unit may output laser light a