| 摘要 |
PURPOSE: A laser irradiation method is provided to uniformly irradiate in the front side of a wafer by irradiating a pulse type laser beam having high frequency as distance from center of the wafer increases. CONSTITUTION: A circular wafer(150) is installed on a stage(100). The stage is installed to be possible to rotate. The wafer is rotated. A pulse type laser beam is irradiated in the front side of the wafer from a processing head(130) which is prepared to be possible to move. The processing head is formed to be possible to move from the center of the wafer to a radial direction of the wafer. Frequency of the pulse type laser beam is controlled by a q-switch which is included in an output end of the processing head. The q-switch comprises an EO(Electro-Optic) q-switch or an AO(Acoustic-Optic) q-switch.
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