Dynamics and mechanism of discrete etching of organic materials by femtosecond laser excitation

Yoichiroh Hosokawa; Masaki Yashiro; Tsuyoshi Asahi; Hiroshi M. Masuhara

doi:10.1117/12.432499

29 June 2001 Dynamics and mechanism of discrete etching of organic materials by femtosecond laser excitation

Yoichiroh Hosokawa, Masaki Yashiro, Tsuyoshi Asahi, Hiroshi M. Masuhara

Proceedings Volume 4274, Laser Applications in Microelectronic and Optoelectronic Manufacturing VI; (2001) https://doi.org/10.1117/12.432499
Event: Photonics West 2001 - LASE, 2001, San Jose, CA, United States

Abstract

Laser ablation and etching of microcrystalline Cu- phthalocyanine thin films were examined by changing pulse duration (170 fs, 250 ps, 100 ns) of a 780 nm Ti:sapphire laser. Above fs (40 mJ/cm²) and ps (50 mJ/cm²) ablation thresholds, the etch depth becomes constant and is almost independent of laser fluence, and further increase in the fs fluence results in complete removal of the film. We name the unique ablation phenomenon discrete etching. On the other hand, the depth etched by ns laser excitation increases gradually with the fluence above its ablation threshold (80 mJ/cm². In order to reveal the difference between the fs and ns etching behaviors, we measured directly excitation energy relaxation and surface morphology change with time-resolved absorption spectroscopy and time- resolved surface scattering imaging, respectively. The fs discrete etching phenomenon and its mechanism were considered in view of time evolutions from highly intense fs laser excitation to the step-wise etching. On the basis of the results, we propose an fs laser ablation model that ultrafast stress increase brings about mechanical disruption leading to the discrete etching behavior.

Citation Download Citation

Yoichiroh Hosokawa, Masaki Yashiro, Tsuyoshi Asahi, and Hiroshi M. Masuhara "Dynamics and mechanism of discrete etching of organic materials by femtosecond laser excitation", Proc. SPIE 4274, Laser Applications in Microelectronic and Optoelectronic Manufacturing VI, (29 June 2001); https://doi.org/10.1117/12.432499

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