Evaluation of the composition and morphology of a WTi/Si system processed by a picosecond laser
Branković, Goran O.
Gaković, Biljana M.
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In this work we studied the influence of laser radiation on the composition, structure and morphology of WTi thin films deposited on n-type (100) silicon wafers. The films were deposited by d.c. sputtering from a 70:30 at% W-Ti target, using Ar ions, to a thickness of similar to 190 nm. Irradiation was performed with a pulsed Nd:YAG laser operating at 1064 nm, whereas the pulse duration was 150 ps. Laser fluences of 3.2 and 5.9 J/cm(2) were found to be sufficient for modification of the WTi/silicon target system. The results show: (i) ablation of WTi thin film and a Si substrate in the central zone of spots, (ii) appearance of hydrodynamic features like resolidified material, (iii) partial ablation of the WTi thin film at the periphery and (iv) appearance of thin film cracks at the far periphery. On the non-ablated areas, the laser modification induced changes in composition, such as inter-mixing of components at the WTi/Si interface with formation of silicides in both metals. Surface ...oxidation was the dominant process in the ablated areas, which is demonstrated by the presence of a SiO2 phase.
Keywords:WTi coating / surface modification / microstructure / interface / oxidation
Source:Metals and Materials International, 2012, 18, 3, 457-463
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- Slovenian Research Agency, Ministry of Science, Education and Sports of the Republic of Croatia