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Proceedings Paper

Improvement of laser dicing performance II: dicing rate enhancement by multi beams and simultaneous aberration correction with phase-only spatial light modulator
Author(s): Yu Takiguchi; Naoya Matsumoto; Masaki Oyaizu; Jyunji Okuma; Makoto Nakano; Takeshi Sakamoto; Haruyasu Itoh; Takashi Inoue
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Paper 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.

Paper Details

Date Published: 15 March 2013
PDF: 9 pages
Proc. SPIE 8608, Laser-based Micro- and Nanopackaging and Assembly VII, 860809 (15 March 2013); doi: 10.1117/12.2003649
Show Author Affiliations
Yu Takiguchi, Hamamatsu Photonics K.K. (Japan)
Naoya Matsumoto, Hamamatsu Photonics K.K. (Japan)
Masaki Oyaizu, Hamamatsu Photonics K.K. (Japan)
Jyunji Okuma, Hamamatsu Photonics K.K. (Japan)
Makoto Nakano, Hamamatsu Photonics K.K. (Japan)
Takeshi Sakamoto, Hamamatsu Photonics K.K. (Japan)
Haruyasu Itoh, Hamamatsu Photonics K.K. (Japan)
Takashi Inoue, Hamamatsu Photonics K.K. (Japan)

Published in SPIE Proceedings Vol. 8608:
Laser-based Micro- and Nanopackaging and Assembly VII
Udo Klotzbach; Yongfeng Lu; Kunihiko Washio, Editor(s)

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