Improvement of laser dicing system performance I: high-speed, high-quality processing of thick silicon wafers using spatial light modulator

Naoya Matsumoto; Yu Takiguchi; Haruyasu Itoh; Masaharu Hoshikawa; Hiroyuki Iwaki; Tsukasa Hasegawa; Makoto Nakano; Masaki Oyaizu; Takeshi Sakamoto; Takafumi Ogiwara; Takashi Inoue

doi:10.1117/12.2003639

15 March 2013 Improvement of laser dicing system performance I: high-speed, high-quality processing of thick silicon wafers using spatial light modulator

Naoya Matsumoto, Yu Takiguchi, Haruyasu Itoh, Masaharu Hoshikawa, Hiroyuki Iwaki, Tsukasa Hasegawa, Makoto Nakano, Masaki Oyaizu, Takeshi Sakamoto, Takafumi Ogiwara, Takashi Inoue

Author Affiliations +

Proceedings Volume 8608, Laser-based Micro- and Nanopackaging and Assembly VII; 860805 (2013) https://doi.org/10.1117/12.2003639
Event: SPIE LASE, 2013, San Francisco, California, United States

Abstract

In the laser wafer dicing technique of stealth dicing (SD), a laser beam that is tightly focused inside a silicon wafer is scanned multiple times at different depths. The focused beam creates multilayered cracks that allow dry, debris-free dicing. To reduce the dicing time, it is desirable to produce longer cracks with each scan. However, when the laser beam is focused in a deep region of the wafer, the beam is blurred, and its power density decreases owing to spherical aberration caused by a refractive index mismatch between air and the wafer. Consequently, the generated cracks become shorter. We present an approach to making longer cracks deep within the wafer by correcting the spherical aberration. This correction is made using an SD machine incorporating a phase-only spatial light modulator to apply aberration correction patterns, which are calculated by a method based on inverse ray tracing. Experimental results using 300-µm wafers show that, when the aberration was corrected, the cracks formed during multidepth scans became longer even deep within the wafer and that the dicing speed with correction is more than twice that without correction. This is because each scan produced longer cracks, so fewer scans were necessary. We also demonstrated that the quality of dicing was improved.

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Naoya Matsumoto, Yu Takiguchi, Haruyasu Itoh, Masaharu Hoshikawa, Hiroyuki Iwaki, Tsukasa Hasegawa, Makoto Nakano, Masaki Oyaizu, Takeshi Sakamoto, Takafumi Ogiwara, and Takashi Inoue "Improvement of laser dicing system performance I: high-speed, high-quality processing of thick silicon wafers using spatial light modulator", Proc. SPIE 8608, Laser-based Micro- and Nanopackaging and Assembly VII, 860805 (15 March 2013); https://doi.org/10.1117/12.2003639

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