Surface Roughness Modification of Free Standing Single Crystal Silicon Microstructures Using KrF Excimer Laser Treatment for Mechanical Performance Improvement

Mohamed Elwi Mitwally; Toshiyuki Tsuchiya; Osamu Tabata; Sherif Sedky

doi:10.4236/jsemat.2015.51004

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Journal of Surface Engineered Materials ... > Vol.5 No.1, January 2015

Surface Roughness Modification of Free Standing Single Crystal Silicon Microstructures Using KrF Excimer Laser Treatment for Mechanical Performance Improvement ()

Mohamed Elwi Mitwally^1*, Toshiyuki Tsuchiya¹, Osamu Tabata¹, Sherif Sedky²

¹Department of Micro Engineering, Kyoto University, Kyoto, Japan.
²Zewail City of Science and Technology, Cairo, Egypt.

DOI: 10.4236/jsemat.2015.51004 PDF HTML XML 3,230 Downloads 3,809 Views Citations

Abstract

Single crystal silicon freestanding structures for tensile and fatigue testing were treated with KrF excimer laser to improve surface roughness and accordingly mechanical performance. Sample thickness was 5 μm. Localized laser treatment was successful in eliminating the scallops developed during Bosch process and in reducing surface roughness. Harsh irradiation at laser energies up to 4 J/cm² was only possible due to localized treatment without significant vibrations occurring on the freestanding samples that led to fracture in preliminary experiments at energies as low as 0.16 J/cm². Finite element analysis was used to investigate the temperature distribution on the irradiated structures. Atomic force microscopy (AFM) and Raman spectroscopy were also used to assess surface roughness, crystallinity changes and surface stresses developing on surfaces subjected to perpendicular laser irradiation. At a high energy (3.2 J/cm²) the top surface showed a decrease of roughness compared to fabricated samples. Raman spectroscopy showed the dominance of crystalline silicon after laser irradiation. The effects of laser energy, number of pulses

Keywords

Freestanding Mechanical Test Structures, Harsh Laser Treatment, Surface Roughness Improvement

Share and Cite:

Mitwally, M. , Tsuchiya, T. , Tabata, O. and Sedky, S. (2015) Surface Roughness Modification of Free Standing Single Crystal Silicon Microstructures Using KrF Excimer Laser Treatment for Mechanical Performance Improvement. Journal of Surface Engineered Materials and Advanced Technology, 5, 28-41. doi: 10.4236/jsemat.2015.51004.

Conflicts of Interest

The authors declare no conflicts of interest.

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