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The surface laser-induced damage threshold (LIDT) of CsLiB(6)O(10) (CLBO) crystal was enhanced twofold with improved crystallinity and ion-beam etching. For crystals with high crystal quality (bulk LIDT, 15.0-19.0 GW/cm(2)), the surface LIDT was 1.4-fold higher than for those with conventional crystal quality (bulk LIDT, 9.0-12.0 GW/cm(2)). In addition, removal of residual surface-polishing compounds by means of ion-beam etching can further enhance the surface LIDT by another 1.5-fold. Thus, CLBO crystals with high crystal quality and ion-beam etching are now more reliable for high-power UV light generation.

The relationships among the bulk laser-induced damage threshold (LIDT), dislocation density and absorption of laser light in CsLiB6O10 (CLBO) were investigated. A newly developed synthesis process allows the growth of CLBO crystals with a LIDT of 2.5-fold higher than that grown by the conventional top-seeded solution growth (TSSG) technique. High-quality CLBO possesses lower dislocation density (6.6×103/cm2) than conventional CLBO (∼15.0×103/cm2). The absorption of laser light in CLBO was characterized by measuring the temperature increase on the crystal output surface during the generation of fourth-harmonic (@266 nm) light of Nd:YAG lasers. At a UV power of 5 W, the maximum temperature increase was 6°C for high-quality CLBO, which was ∼30% lower than that generated on conventional CLBO crystal. Thus, the reduction of dislocation density can suppress the absorption of laser light, which helps to enhance the resistance of CLBO against laser-induced damage and alleviate thermal dephasing during the high-power generation of UV light.

In order to improve the yield enhancement speed, we adopt data mining analysis. The root cause of crack in silicon substrate induced by scrubber tool was found by data mining approach. It could not be detected by conventional knowledge-based pre-filtering approach. As a countermeasure, we switched the scrubber from high pressure clean tool to moderate pressure clean tool.

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