Wavelength conversion method, wavelength conversion laser, and laser beam machining apparatus

Abstract

A fundamental laser beam to is wavelength converted through nonlinear optical crystals by traveling in one direction, sequentially through two nonlinear optical crystals arranged in series. A wavelength-converted laser beam is generated and includes wavelength-converted laser beams having polarized directions differing from each other by angles in a range from 45 DEG to 90 DEG . The two nonlinear optical crystals have crystal orientation axes differing by 45 DEG to 90 DEG when viewed along the optical axis of the laser beam.

Description

technical field [0001] The present invention relates to laser beam-to-wavelength conversion by using a nonlinear optical crystal, and more particularly, to a technique for machining a workpiece by emitting a wavelength-converted laser beam to the workpiece. Background technique [0002] In the wavelength conversion laser disclosed in JP-A-5-142607 (pp. 3 to 4, and Fig. 1), when two nonlinear optical crystals are connected in series with each other, the nonlinear optical crystal is above are the same length. One of the NLO crystals is aligned with the incident laser beam with respect to the crystal orientation axis for phase matching. After passing through the first nonlinear optical crystal, the incident laser beam enters the second nonlinear optical crystal. Here, the second nonlinear optical crystal is located at a position where the crystal orientation axis of the second crystal used for phase matching is offset from the crystal orientation axis of the first crystal by ...

AI Technical Summary

Problems solved by technology

[0009] According to the laser machining method of the related art, when exposure is performed using a wavelength-converted laser beam emitted from a wavelength conversion laser equipped with a wavelength converter, the wavelength-converted laser beam emitted from the wavelength conversion laser (that is, the wavelength converter) Lasers are usually linearly polarized, which creates the problem that machining results can be biased depending on the machining direction and polarization direction

Specifically, in machining to obtain polysilicon by irradiating a laser beam on amorphous silicon and annealing the thus exposed silicon, when a device such as a thin film transistor is passed using a substrate (which has been passed through When the conventional laser beam machining method is converted to polysilicon) for manufacturing, there arises such a problem that deviations occur in features depending on the relationship between the scanning direction and the polarization direction of the laser beam

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