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Laser machining of silicon with bursts of ultra-short laser pulses: Factors influencing the process efficiency and surface quality (Conference Presentation)
Author(s): Beat Neuenschwander; Stefan Remund; Thorsten Kramer

Paper Abstract

For silicon machined with 10 ps pulses at 1064nm it was found that the specific removal rate increases by a factor of about 2.5 when an 8-pulse burst is used instead of single pulses [1]. This increase in the specific removal rate directly scales with a higher surface roughness. For copper and a 3-pulse burst the absorptance of a machined surface increases to about 200% of the one obtained with single pulses [2]. This can serve as an explanation for the higher specific removal rate observed in this case [3]. Actual calorimetric measurements on silicon show that the fraction of the incoming energy which is converted to heat is almost independent on the number of pulses per burst (a behavior which was observed for copper too) and the absorptance depends on the number of pulses. However, as the observed variations in the absorptance are only in the order of a few % and do not monotonically increase with the number of pulses per burst the change in the absorptance cannot explain the increase in the specific removal rate for pulse bursts on silicon. Additional experiments including calorimetry with varying intra-burst time differences and pulse energies as well as experiments concerning reflectivity and transmission will help to understand this behavior of silicon. [1] B. Jaeggi, D.J. Förster, B. Neuenschwander, OSA Technical Digest, CLEO (2018), AM1M.3 [2] B. Jaeggi, D. J. Foerster, R. Weber, B. Neuenschwander, Adv. Opt. Techn. 7, 175 (2018) [3] B. Neuenschwander, B. Jaeggi, D.J. Foerster, Th. Kramer, S. Remund, to be published in Proc. of ICALEO (2018)

Paper Details

Date Published: 13 March 2019
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Proc. SPIE 10905, Laser Applications in Microelectronic and Optoelectronic Manufacturing (LAMOM) XXIV, 1090503 (13 March 2019); doi: 10.1117/12.2513297
Show Author Affiliations
Beat Neuenschwander, Berner Fachhochschule Technik und Informatik (Switzerland)
Stefan Remund, Berner Fachhochschule Technik und Informatik (Switzerland)
Thorsten Kramer, Berner Fachhochschule Technik und Informatik (Switzerland)


Published in SPIE Proceedings Vol. 10905:
Laser Applications in Microelectronic and Optoelectronic Manufacturing (LAMOM) XXIV
Tetsuya Makimura; Gediminas Račiukaitis; Carlos Molpeceres, Editor(s)

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