著者

大村 悦二 野村 和史 宮本 勇

出版者

一般社団法人 溶接学会

雑誌

溶接学会論文集 (ISSN:02884771)

巻号頁・発行日

vol.21, no.3, pp.344-349, 2003 (Released:2004-11-16)

参考文献数

5

---

In recent years, applications of solid-state lasers with frequency conversion techniques such as SHG, THG and FHG to precision microfabrication progress rapidly. When nonlinear optical crystal used for frequency conversion absorbs laser beam, temperature of the crystal rises, and the frequency-conversion efficiency decreases. In this study, KH2PO4, that is potassium dihydrogen phosphate (KDP), whose physical properties are well known was supposed as a nonlinear optical crystal for SHG. Temperature dependence of frequency-conversion efficiency was examined theoretically by solving the coupling problem composed of heat conduction equation and complex amplitude equations, which are derived considering the absorption of laser in the crystal. The temperature change of the crystal induced by Nd:YAG laser absorption, the local change of refractive indices, and the consequential variation of SHG frequency-conversion efficiency were analyzed for single and repetitive pulses. As a result, the temperature dependence of frequency-conversion became clear quantitatively. Remarkable inverse-conversion of SHG also appears for the repeated laser irradiation with high power density.

著者

大村 悦二 小川 健輔 熊谷 正芳 中野 誠 福満 憲志 森田 英毅

出版者

一般社団法人日本機械学会

雑誌

日本機械学會論文集. A編 (ISSN:03875008)

巻号頁・発行日

vol.76, no.764, pp.446-448, 2010-04-25

---

In stealth dicing (SD), a permeable nanosecond laser is focused inside a silicon wafer and scanned horizontally. A thermal shock wave is propagated every pulse toward the side to which the laser is irradiated, then a high dislocation density layer is formed inside a wafer after the thermal shock wave propagation. In our previous study, it was supposed that an internal crack whose initiation is a dislocation is propagated when the thermal shock wave by the next pulse over-laps with this layer partially. In this study, a two-dimensional thermal elasticity analysis based on the fracture mechanics was conducted. The internal crack propagation was analyzed by calculating the stress intensity factor at the crack tips and comparing with a threshold of that. As a result, validity of the previous hypothesis was suggested.

著者

大村 悦二 小川 健輔 熊谷 正芳 中野 誠 福満 憲志 森田 英毅

出版者

一般社団法人日本機械学会

雑誌

M&M材料力学カンファレンス

巻号頁・発行日

vol.2009, pp.73-74, 2009-07-24

---

In stealth dicing (SD), a permeable nanosecond laser is focused inside a silicon wafer and scanned horizontally. A thermal shock wave is propagated every pulse toward the side to which the laser is irradiated, then a high dislocation density layer is formed inside a wafer after the thermal shock wave propagation. In our previous study, it was supposed that an internal crack whose initiation is a dislocation is propagated when the thermal shock wave by the next pulse overlaps with this layer partially. In this study, a two-dimensional thermal elasticity analysis based on the fracture mechanics was conducted. The internal crack propagation was analyzed by calculating the stress intensity factor at the crack tips and comparing with a threshold of that. As a result, validity of the previous hypothesis was suggested.