STUDY ON LASER CLEAVAGE OF THICK SAPPHIRE WAFER WITH CO₂ LASER BEAM

-REDUCTION OF WAVINESS IN CLEAVADE SURFACE-

抄録

This study deals with the thermal stress cleavage of sapphire wafer with a thickness of 5 mm by CO₂ laser beam irradiation. The influence of the distance from the edge to the initial crack on the cleavage characteristics was investigated experimentally. As results, the waviness on the cleaved surface was quite influenced by the distance from the edge to the cleaved position. When the distance from the edge was 6 mm, the waviness of the cleaved surface was 840 µm, and its value was improved to 162 µm under the distance from the edge of 18 mm. In addition, the laser power required for the cleavage was increased as the distance from the edge was increased. On the other hand, the periodical wavy surface was obtained when the laser power was quite large. The wavy surface was improved by lowering the laser power.