Product Code: ICAL09_M603

Influence of Polarization Plane on Groove Shape in Scribing of Sapphire by THG:YAG Laser
Authors:
Yasuhiro Okamoto, Okayama University; Okayama Japan
Tomokazu Sakagawa, Kataoka Corporation; Yokohama Japan
Yoshiyuki Uno, Okayama University; Okayama Japan
Yutaka Mukoya, Okayama University; Okayama Japan
Yuki Okamura, Okayama University; Okayama Japan
Presented at ICALEO 2009

Scribing characteristics of mono-crystalline sapphire by using THG:YAG laser of 355nm in wavelength were investigated. The influence of polarization plane of laser beam on the curved shape at the tip of groove was also discussed. Moreover, the reflection of laser beam was experimentally investigated in order to clarify the generation mechanism of curved shape. The groove width and the laser affected zone of groove wall could be decreased under the high pulse repetition rate condition. Moreover, the absorptivity of laser beam at high pulse repetition rate was still kept at higher range, although the feed rate became high. Therefore, the high pulse repetition condition is very effective for the laser scribing of sapphire. The curved shape at the tip of groove was greatly influenced by the direction of polarization plane of laser beam. This phenomenon occurred not randomly but regularly depending on the angle of polarization plane. In the direction of curved shape generation, in other words, in the vertical direction to the polarization plane of laser beam, the laser beam was reflected strongly. Therefore, the reflection of laser beam from the processing point has a close relation to the curved shape at the tip of the groove. Consequently, a suitable setting of polarization plane could make the straight groove without the occurrence of curved shape.