Machining of semiconductors and dielectrics with ultra-short pulses: Influence of the wavelength and pulse bursts (Conference Presentation)

Neuenschwander, Beat; Jäggi, Beat; Remund, Stefan Marco; Zavedeev, E.; Pimenov, Sergei M. (2018). Machining of semiconductors and dielectrics with ultra-short pulses: Influence of the wavelength and pulse bursts (Conference Presentation) In: Laser Applications in Microelectronic and Optoelectronic Manufacturing (LAMOM) XXIII (p. 3). SPIE 10.1117/12.2291909

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n the burst mode the reported removal rates were often higher than the ones achieved with single pulses at identical repetition rate and average power. But this effect is mainly caused by the reduced energy per single pulse in the burst and the corresponding fluence which is then nearer its optimum value showing highest specific removal rate. But there exist special situations where the burst mode shows a higher efficiency and therefore an increased specific removal rate. For copper e.g. it was found that a 3-pulse burst with a time spacing of 12 ns at a wavelength of 1064 nm leads to an about 15% higher specific removal rate. We extended the burst investigations to semiconductors and isolators and measured the specific removal rate as a function of the applied peak fluence for different materials, number of pulses in the burst and time spacing. For 1064nm silicon e.g. shows a maximum specific removal rate which amounts about 1.7µm3/µJ for single pulses and a 2 pulse burst as well. Then it almost linearly increases up to about 5 µm3/µJ when the number of pulses in the burst is raised to 8. A similar effect is found for machining grooves into diamond-like nanocomposite films with single pulses and a 2- and 3-pulse burst, respectively. In contrast, for silicon and 532 nm wavelength where the photon energy exceeds the bandgap, only a small difference in the maximum specific removal was observed. Heat accumulation is assumed to cause the higher specific removal rates but further experiments are needed gain a clearer picture.

Item Type:	Conference or Workshop Item (Speech)
Division/Institute:	School of Engineering and Computer Science > Institute for Surface Applied Laser, Phototonics and Surface Technologies ALPS
Name:	Neuenschwander, Beat0000-0001-9715-8557; Jäggi, Beat; Remund, Stefan Marco; Zavedeev, E. and Pimenov, Sergei M.
Subjects:	Q Science > QC Physics T Technology > TA Engineering (General). Civil engineering (General)
ISBN:	9781510615243
Publisher:	SPIE
Language:	English
Submitter:	Beat Neuenschwander
Date Deposited:	25 Mar 2020 12:21
Last Modified:	04 Nov 2021 21:46
Publisher DOI:	10.1117/12.2291909
Additional Information:	Copyright 2018 Society of Photo‑Optical Instrumentation Engineers (SPIE). One print or electronic copy may be made for personal use only. Systematic reproduction and distribution, duplication of any material in this publication for a fee or for commercial purposes, and modification of the contents of the publication are prohibited
ARBOR DOI:	10.24451/arbor.9234
URI:	https://arbor.bfh.ch/id/eprint/9234