Product Code: ICA12_M601

Selective Femtosecond Laser Structuring of a Platinum/Tantalum Pentoxide Thin Film Layer System by Induced Laser Ablation Investigated with Pump-Probe Microscopy
Authors:
Janosch Rosenberger, Munich Univ. of Applied Sciences; Munich Germany
Stephan Rapp, Munich Univ. of Applied Sciences; -
Matthias Domke, Munich Univ. of Applied Sciences; Munich Germany
Gerhard Heise, Munich Univ. of Applied Sciences; Munich Germany
Heinz P. Huber, Munich Univ. of Applied Sciences; Munich Germany
Presented at ICALEO 2012

A biocompatible sensor chip consists of a 200 nm conducting platinum layer between a glass substrate and a 200 nm tantalum pentoxide layer as insulator on top. The irradiation of the biochip from the Ta2O5 side with ultra-short laser pulses ( 660 fs) at a wavelength of 1053 nm leads to a selective ablation of the Ta2O5 layer from the platinum. The ablation threshold for the removal of the Ta2O5 layer is about 0.08 J/cm². Moreover, the Ta2O5 lifts-off in form of an intact disk at a fluence of 0.14 J/cm². For deeper understanding of the ablation mechanisms, a pump-probe microscopy setup was utilized to record a stop-motion movie of the lift-off process. The setup utilizes an optically combined with an electronically delayed probe pulse. For the first time to our knowledge the laser lift-off of a transparent oxide could be recorded over the complete temporal dynamic range. The movies reveal that an intact disk leaves the hole after a few 10 ns. At higher fluences of about 0.20 J/cm.