O12.6 Fracture and Deformation of Thermal Oxide Films on Si (100) Using a Femtosecond Pulsed Laser
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O12.6.1
O12.6 Fracture and Deformation of Thermal Oxide Films on Si (100) Using a Femtosecond Pulsed Laser Authors: Joel P. McDonald1,4, Vanita R. Mistry2, Katherine E. Ray2, Steven M. Yalisove3,4 1
Applied Physics Program, University of Michigan, 2477 Randall Laboratory, Ann Arbor, MI 48109-1120 College of Engineering, University of Michigan, Lurie Engineering Center, 1221 Beal Avenue, Ann Arbor, MI 48109-2102 3 Deparment of Materials Science and Engineering, University of Michigan, 2200 Hayward Ave., Ann Arbor, MI 48109 4 Center for Ultrafast Optical Science, University of Michigan, 1006 Gerstacker Building, 2200 Bonisteel Avenue, Ann Arbor, MI 48109 2
Abstract: Femtosecond pulsed laser damage of Silicon (100) with thermal oxide thin films was studied in order to further understand the optical and electrical properties of thin films and to evaluate their influence on the damage of the substrate. The damage threshold as a function of film thickness (2 – 1200 nm) was measured. The damage morphology produced by single laser pulses was also investigated. Two primary morphologies were observed, one in which the oxide film is completely removed, and the other in which the film is delaminated and expanded above the surface producing a bubble feature. Introduction: In this work, the mechanical properties of Si – SiO2 structures are probed in an extreme fashion using high intensity femtosecond (fs) laser pulses. As the electrical and mechanical properties of Silicon are fairly well understood, Si has been a material of choice for fs laser damage studies [1-3]. Recently our work has shown that the naturally occurring ~2 nm thick native oxide layer supported by Si(100) influences both fs laser damage morphology and single shot damage threshold. In this work we have studied fs laser ablation of Si(100) with oxide films ranging in thickness from the ~ 2 nm native oxide up to the 1200 nm of thermal oxide (SiO2). Our goal was to determine if the damage threshold and damage morphology of Si(100) with a surface oxide thin film was dependent on the oxide film thickness. The following focuses on two results obtained during fs laser ablation studies of oxide thin films on Si(100) substrates. First, the damage threshold of Si(100) with a thermally grown oxide is presented as a function of thermal oxide film thickness (with laser incident perpendicular to sample surface, i.e. normal incidence). Second, the surface damage morphology resulting from single fs laser pulses incident on Si(100) with thermal oxide films is presented. Two different laser fluence dependent morphology types were observed, with variations within these types observed for different oxide layer thickness and laser beam angle of incidence. For laser fluences above a thickness dependent threshold, the oxide layer was removed in a nearly discrete fashion. For laser fluences below this threshold, uniform dome structures were produced, where the glass film appears to “bubble” out from the substrate. The domes are thought to result from a combination of thin film delam
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