Improvement of laser dicing performance II: dicing rate enhancement by multi beams and simultaneous aberration correction with phase-only spatial light modulator

Yu Takiguchi; Naoya Matsumoto; Masaki Oyaizu; Jyunji Okuma; Makoto Nakano; Takeshi Sakamoto; Haruyasu Itoh; Takashi Inoue

doi:10.1117/12.2003649

15 March 2013 Improvement of laser dicing performance II: dicing rate enhancement by multi beams and simultaneous aberration correction with phase-only spatial light modulator

Yu Takiguchi, Naoya Matsumoto, Masaki Oyaizu, Jyunji Okuma, Makoto Nakano, Takeshi Sakamoto, Haruyasu Itoh, Takashi Inoue

Author Affiliations +

Proceedings Volume 8608, Laser-based Micro- and Nanopackaging and Assembly VII; 860809 (2013) https://doi.org/10.1117/12.2003649
Event: SPIE LASE, 2013, San Francisco, California, United States

Abstract

“Stealth Dicing” laser processing is a dry and debris-free semiconductor wafer dicing method achieved by generating thermal micro-cracks inside a wafer with a tightly focused laser beam. This method has two practical issues: (1) the dicing speed is limited by the repetition rate of the pulsed laser, and (2) integrated circuits on the opposite side of the wafer from the laser light are potentially damaged by excessive laser intensity required to compensate for insufficient beam convergence. The insufficient beam convergence is a result of spherical aberration due to a refractive index mismatch between air and the wafer. These problems can be resolved by incorporating a phase-only spatial light modulator (SLM) into the laser dicing system. The SLM produces two types of wavefront configurations simultaneously for two different functions. One is for multi-beam generation with a phase grating pattern. This improves the dicing speed by a factor equal to the number of diffracted beams. The other is for aberration correction of the multiple beams using a pre-distorted wavefront pattern. By correcting aberrations, the focused multiple beams inside the wafer will become sufficiently convergent to avoid undesirable laser damage. We demonstrated these improvements by dicing sapphire wafers with a pulsed laser and a high-numerical-aperture objective lens.

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Yu Takiguchi, Naoya Matsumoto, Masaki Oyaizu, Jyunji Okuma, Makoto Nakano, Takeshi Sakamoto, Haruyasu Itoh, and Takashi Inoue "Improvement of laser dicing performance II: dicing rate enhancement by multi beams and simultaneous aberration correction with phase-only spatial light modulator", Proc. SPIE 8608, Laser-based Micro- and Nanopackaging and Assembly VII, 860809 (15 March 2013); https://doi.org/10.1117/12.2003649

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