Laser oscillation mechanism

Abstract

The invention provides a laser oscillation mechanism. A laser oscillation mechanism includes a pulse laser oscillator configured to oscillate a pulse laser beam, and a branching unit which branches the pulse laser beam oscillated by the pulse laser oscillator. The branching unit includes a diffraction optical element and a volume Bragg grating. The diffraction optical element(DOE) branches the pulse laser beam oscillated by the pulse laser oscillator into a plurality of laser beams in an effective region. The volume Bragg grating(VBG) refracts, from among the pulse laser beams branched by the diffraction optical element, a particular pulse laser beam to be excluded from the effective region to exclude the particular pulse laser beam.

Description

technical field [0001] The present invention relates to a laser oscillation mechanism installed in a laser processing device or the like for performing laser processing on a workpiece. Background technique [0002] In the manufacturing process of semiconductor devices, a plurality of regions are divided by planned division lines arranged in a grid pattern on the surface of a substantially disc-shaped semiconductor wafer, and devices such as ICs and LSIs are formed on the divided regions. . Then, the semiconductor wafer is cut along the planned dividing line to divide the region where the device is formed. Each semiconductor device is manufactured. [0003] As a method of dividing the above-mentioned wafer, a laser processing method may be attempted in which a pulsed laser beam having a transmissive wavelength is used on the wafer, and a converging point is aligned inside a region to be divided to irradiate the pulsed laser beam. The division method using this laser proces...

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Problems solved by technology

[0008] Moreover, when a beam splitter is used in order to branch the laser beam oscillated by the laser beam oscillator into a plurality of laser beams to form a plurality of focusing points as in the laser beam irradiation units disclosed in the above-mentioned Patent Documents 1 and 2, it will be divided into The energy density per pulse is halved for p-polarized light and s-polarized light, and the polarization planes are different from each other, resulting in unstable processing quality.

[0009] In addition, if the laser beam is branched using a diffractive optical element (DOE), the energy density of each pulse can be maintained without branching into p-polarized light and s-polarized light, so the above-mentioned problems will not occur. However, due to the diffractive optical element ( The branching angle of DOE) is small, so in order to exclude the zero-order light passing through the diffractive optical element (DOE), it is necessary to install a laser light absorption unit at the center of the diffractive optical element (DOE) at a distance of 1 to several meters. There is a problem making the device larger

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