Title: Ablation threshold dependence on incident wavelength during ultrashort pulsed laser ablation

Authors: Reece N. Oosterbeek; Simon Ashforth; Owen Bodley; M. Cather Simpson

Addresses: Photon Factory, School of Chemical Sciences, The University of Auckland, 23 Symonds Street, Bldg 301, Auckland 1010, New Zealand ' Department of Physics, The University of Auckland, 23 Symonds Street, Bldg 303, Auckland 1010, New Zealand ' Photon Factory, School of Chemical Sciences, The University of Auckland, 23 Symonds Street, Bldg 301, Auckland 1010, New Zealand ' Photon Factory, School of Chemical Sciences, The University of Auckland, 23 Symonds Street, Bldg 301, Auckland 1010, New Zealand; Department of Physics, The University of Auckland, 23 Symonds Street, Bldg 303, Auckland 1010, New Zealand

Abstract: Ultrashort pulse laser micromachining is an advanced materials processing technique that allows "cold cutting" of almost any material. This is especially of interest in the semiconductor industry, where mechanical cutting of wafers generates large amounts of waste - if laser micromachining could be applied here, there is the potential for huge increases in the efficiency and flexibility of semiconductor manufacturing. The biggest barrier to industrial application of this technology is the cutting speed, however by tailoring the pulse properties, we hypothesise that machining speed can be increased greatly. The commonly used metric for evaluation of laser micromachining is the ablation threshold - the energy density required to cause material ablation. In this study the effect of incident laser wavelength on the ablation threshold for materials of interest for microfabrication (e.g., silicon) was investigated. This was achieved using a Ti:Sapphire pumped optical parametric amplifier (TOPAS-C) producing femtosecond pulses (τ = 110 fs, repetition rate = 1 kHz) with wavelengths ranging from 400 nm to 1200 nm using the D-Scan technique. Future work will employ advanced beam shaping technology to tailor pulses in both the spatial and temporal domains to further improve machining efficiency.

Keywords: femtosecond laser micromachining; ultrafast laser micromachining; ablation threshold dependence; diagonal scanning; ultrashort pulsed laser ablation; semiconductor manufacturing; cutting speed; incident laser wavelength.

DOI: 10.1504/IJNT.2017.082452

International Journal of Nanotechnology, 2017 Vol.14 No.1/2/3/4/5/6, pp.313 - 322

Published online: 20 Feb 2017 *

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