Selective femtosecond laser structuring of dielectric thin films with different band gaps: a time-resolved study of ablation mechanisms

Rapp S, Schmidt M, Huber HP (2016)

Publication Type: Journal article

Publication year: 2016

Journal

Applied Physics A: Materials Science and Processing Springer Verlag (Germany)

Book Volume: 122

Article Number: 1035

Journal Issue: 12

DOI: 10.1007/s00339-016-0571-0

Abstract

Ultrashort pulse lasers have been increasingly gaining importance for the selective structuring of dielectric thin films in industrial applications. In a variety of works the ablation of thin SiO 2 and SiN x films from Si substrates has been investigated with near infrared laser wavelengths with photon energies of about 1.2 eV where both dielectrics are transparent (Egap,SiO2≈8eV;Egap,SiNx≈2.5eV). In these works it was found that few 100 nm thick SiO 2 films are selectively ablated with a “lift-off” initiated by confined laser ablation whereas the SiN x films are ablated by a combination of confined and direct laser ablation. In the work at hand, ultrafast pump-probe imaging was applied to compare the laser ablation dynamics of the two thin film systems directly with the uncoated Si substrate—on the same setup and under identical parameters. On the SiO 2 sample, results show the pulse absorption in the Si substrate, leading to the confined ablation of the SiO 2 layer by the expansion of the substrate. On the SiN x sample, direct absorption in the layer is observed leading to its removal by evaporation. The pump-probe measurements combined with reflectivity corrected threshold fluence investigations suggest that melting of the Si substrate is sufficient to initiate the lift-off of an overlaying transparent film—evaporation of the substrate seems not to be necessary.

Authors with CRIS profile

Michael Schmidt Lehrstuhl für Photonische Technologien

Involved external institutions

Hochschule für angewandte Wissenschaften München

Germany (DE)

How to cite

APA:

Rapp, S., Schmidt, M., & Huber, H.P. (2016). Selective femtosecond laser structuring of dielectric thin films with different band gaps: a time-resolved study of ablation mechanisms. Applied Physics A: Materials Science and Processing, 122(12). https://dx.doi.org/10.1007/s00339-016-0571-0

MLA:

Rapp, Stephan, Michael Schmidt, and Heinz P. Huber. "Selective femtosecond laser structuring of dielectric thin films with different band gaps: a time-resolved study of ablation mechanisms." Applied Physics A: Materials Science and Processing 122.12 (2016).

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