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Trans-wafer removal of metallization using a nanosecond Tm:fiber laser

: Mingareev, I.; Berger, S.; Tetz, T.; Abdulfattah, A.; Sincore, A.M.; Shah, L.; Richardson, M.C.


Society of Photo-Optical Instrumentation Engineers -SPIE-, Bellingham/Wash.:
Laser applications in microelectronic and optoelectronic manufacturing (LAMOM) XX. Proceedings : 9 - 12 Februar 2015, San Francisco, California, United States
Bellingham, WA: SPIE, 2015 (SPIE Proceedings 9350)
ISBN: 978-1-62841-440-0
Paper 93500B
Conference "Laser Applications in Microelectronic and Optoelectronic Manufacturing" (LAMOM) <20, 2015, San Francisco/Calif.>
Conference Paper
Fraunhofer ILT ()

By utilizing photon energies considerably smaller than the semiconductors' energy band gap, space-selective modifications can be induced in semiconductors beyond the laser-incident surface. Previously, we demonstrated that back surface modifications could be produced in 500-600 mu m thin Si and GaAs wafers independently without affecting the front surface. In this paper, we present our latest studies on trans-wafer processing of semiconductors using a self-developed nanosecond-pulsed thulium fiber laser operating at the wavelength 2 mu m. A qualitative study of underlying physical mechanisms responsible for material modification was performed. We explored experimental conditions that will enable many potential applications such as trans-wafer metallization removal for PV cell edge isolation, selective surface annealing and wafer scribing. These processes were investigated by studying the influence of process parameters on the resulting surface morphology, microstructure and electric properties.