title: Very large spot size effect in nanosecond laser drilling efficiency of silicon.
abstract: The effect of the spot diameter in nanosecond excimer laser percussion drilling of through via in silicon wafer is presented. Experimental results show a ten fold increase of the ablation efficiency when decreasing the spot diameter from 220 μm to 9 μm at constant fluence in the range 7.5 J/cm(2) to 13.2 J/cm(2). Such effect is absent when using 60 ps deep-UV laser pulses. A model is developed that explain the findings in terms of plume shielding effect on the laser pulse. The model is successfully applied also on previously published data on deep-UV laser drilling of Polyamide and Alumina.
authors.affiliation: Nanophysics Group, Italian Institute of Technology, Via Morego 30, Genova, Italy. fernando.brandi@iit.it
authors.forename: Fernando
authors.initials: F
authors.lastname: Brandi
authors.forename: Nicolas
authors.initials: N
authors.lastname: Burdet
authors.forename: Riccardo
authors.initials: R
authors.lastname: Carzino
authors.forename: Alberto
authors.initials: A
authors.lastname: Diaspro