Fiber lasers trump DPSS for thin-wafer slicing
In 2008, Mobius Photonics (Mountain View, CA) introduced UV laser sources based on the harmonic-wavelength conversion of the output of a seeded optical fiber amplifier.
In 2008, Mobius Photonics (Mountain View, CA) introduced UV laser sources based on the harmonic-wavelength conversion of the output of a seeded optical fiber amplifier (technology obtained by entering into an exclusive licensing agreement with Harvard University—see http://bit.ly/7bVWUl). Today, Mobius has publicly announced that its UV laser sources are performing better than diode-pumped solid-state (DPSS) lasers for thin-wafer dicing, as well as for other material and microelectronics processing applications, including thin-film solar-cell scribing and for use as the depletion beam in stimulated-emission-depletion (STED) microscopy studies.
Today, 50 µm thick wafers diced with DPSS UV lasers produce dies with significantly lower break strength compared to conventional mechanical methods. But Mobius' all-fiber-amplifier, master-oscillator-power-amplifier architecture nanosecond UV source technology, thanks to its multiple wavelengths and variable pulse-repetition frequencies (200 kHz to 20 MHz) and pulsewidths, produces dies with strength comparable to mechanical methods. For 50 µm thick wafers, the Mobius laser produces dies with average die-strength values of 657 MPa, compared to 367 MPa for DPSS Q-switched UV lasers. Mobius fiber lasers also produce smooth, continuous scribe lines in glass substrates (without chipping) and generate 1 µm diameter uniform through-holes in 25 µm thick polyimide. For wafer-dicing applications, actual die-strength data and a minimum/maximum value can be disclosed under a nondisclosure agreement. Contact Kiyomi Monro at email@example.com.