JSEMAT  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
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
Cite this paper: 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.

[1]   Yi, T., Li, L. and Kim, C.J. (2000) Microscale Material Testing of Single Crystalline Silicon: Process Effects on Surface Morphology and Tensile Strength. Sensors and Actuators A: Physical, 83, 172-178.

[2]   Pierron, O.N. and Muhlstein, C.L. (2006) The Critical Role of Environment in Fatigue Damage Accumulation in Deep-Reactive Ion-Etched Single-Crystal Silicon Structural Films. Journal of Microelectromechanical Systems, 15, 111-119.

[3]   Alsem, D.H., Boyce, B.L., Stach, E.A. and Ritchie, R.O. (2008) Effect of Post-Release Sidewall Morphology on the Fracture and Fatigue Properties of Polycrystalline Silicon Structural Films. Sensors and Actuators A: Physical, 147, 553-560.

[4]   Liang, E.Z., Hung, S.C., Hsieh, Y.P. and Lin, C.F. (2008) Effective Energy Densities in KrF Excimer Laser Reformation as a Sidewall Smoothing Technique. Journal of Vacuum Science & Technology B, 26, 110-116.

[5]   Hung, S.C., Liang, E.Z. and Lin, C.F. (2009) Silicon Waveguide Sidewall Smoothing by KrF Excimer Laser Reformation. Journal of Lightwave Technology, 27, 887-892.

[6]   Yan, J.W., Asami, T. and Kuriyagawa, T. (2009) Complete Recovery of Subsurface Structures of Machining-Damaged Single Crystalline Silicon by Nd: YAG Laser Irradiation. Key Engineering Materials, 389, 469-474.

[7]   Yan, J., Sakai, S., Isogai, H. and Izunome, K. (2009) Recovery of Microstructure and Surface Topography of Grinding- Damaged Silicon Wafers by Nanosecond-Pulsed Laser Irradiation. Semiconductor Science and Technology, 24, Article ID: 105018.

[8]   Bosseboeuf, A., Boulmer, J. and Débarre, D. (1997) Planarization of Rough Silicon Surfaces by Laser Annealing. Applied Surface Science, 109, 473-476.

[9]   Kim, S.G., Roh, T.M., Kim, J., et al. (2003) Behavior of Trench Surface by H2 Annealing for Reliable Trench Gate Oxide. Journal of Crystal Growth, 255, 123-129.

[10]   Lee, M.C.M., and Wu, M.C. (2006) Thermal Annealing in Hydrogen for 3-D Profile Transformation on Silicon-on- Insulator and Sidewall Roughness Reduction. Journal of Microelectromechanical Systems, 15, 338-343.

[11]   Takahashi, J.I., Tsuchizawa, T., Watanabe, T. and Itabashi, S.I. (2004) Oxidation-Induced Improvement in the Sidewall Morphology and Cross-Sectional Profile of Silicon Wire Waveguides. Journal of Vacuum Science and Technology B: Microelectronics and Nanometer Structures, 22, 2522-2525.

[12]   Sparacin, D.K., Spector, S.J. and Kimerling, L.C. (2005) Silicon Waveguide Sidewall Smoothing by Wet Chemical Oxidation. Journal of Lightwave Technology, 23, 2455-2461.

[13]   Rogers, J.W. and Phinney, L.M. (2004) Temperature Response of Silicon MEMS Cantilevers during and after Nd: YAG Laser Irradiation. Numerical Heat Transfer, Part A: Applications, 45, 737-750.

[14]   Rogers, J.W. and Phinney, L.M. (2001) Process Yields for Laser Repair of Aged, Stiction-Failed, MEMS Devices. Journal of Microelectromechanical System, 10, 280-285.

[15]   Zhang, X.R. and Xu, X. (2005) Laser Bending for High-Precision Curvature Adjustment of Microcantilevers. Applied Physics Letters, 86, Article ID: 021114.

[16]   Dirscherl, M., Esser, G. and Schmidt, M. (2006) Ultrashort Pulse Laser Bending. Journal of Laser Micro/Nanoengi- neering, 1, 54-60.

[17]   Mitwally, M.E., Tsuchiya, T., Tabata, O. and Sedky, S. (2014) Improvement of Tensile Strength of Freestanding Single Crystal Silicon Microstructures Using Localized Harsh Laser Treatment. Japanese Journal of Applied Physics, 53, Article ID: 06JM03.

[18]   Tsuchiya, T., Shikida, M. and Sato, K. (2002) Tensile Testing System for Sub-Micrometer Thick Films. Sensors and Actuators A: Physical, 97, 492-496.

[19]   Ikehara, T. and Tsuchiya, T. (2008) High-Cycle Fatigue of Micromachined Single-Crystal Silicon Measured Using High-Resolution Patterned Specimens. Journal of Micromechanics and Microengineering, 18, Article ID: 075004.

[20]   Alsem, D.H., Pierron, O.N., Stach, E.A., Muhlstein, C.L. and Ritchie, R.O. (2007) Mechanisms for Fatigue of Micron-Scale Silicon Structural Films. Advanced Engineering Materials, 9, 15-30.

[21]   Darif, M., Semmar, N. and Orléans Cedex, F. (2008) Numerical Simulation of Si Nanosecond Laser Annealing by COMSOL Multiphysics. Proceedings of the COMSOL Conference, Hannover, 2008.

[22]   Anthony, T.R. and Cline, H.E. (1977) Surface Rippling Induced by Surface-Tension Gradients during Laser Surface Melting and Alloying. Journal of Applied Physics, 48, 3888-3894.

[23]   Amutha, G., Palani, I.A., Vasa, N.J., Singaperumal, M. and Okada, T. (2013) Investigations on Nano- and Pico-Second Laser Based Annealing Combined Texturing of Amorphous Silicon Thin Films for Photovoltaic Applications. Journal of Solid Mechanics and Materials Engineering, 7, 206-216.

[24]   Palani, I.A., Vasa, N.J., Singaperumal, M. and Okada, T. (2010) Investigation on Laser-Annealing and Subsequent Laser-Nanotexturing of Amorphous Silicon (a-Si) Films for Photovoltaic Application. Journal of Laser Micro/Nanoengi- neering, 5, 150-155.

[25]   Nayak, B.K., Sun, K., Rothenbach, C. and Gupta, M.C. (2011) Self-Organized 2D Periodic Arrays of Nanostructures in Silicon by Nanosecond Laser Irradiation. Applied Optics, 50, 2349-2355.

[26]   De Wolf, I. (1996) Micro-Raman Spectroscopy to Study Local Mechanical Stress in Silicon Integrated Circuits. Semiconductor Science and Technology, 11, 139-154.

[27]   Steen, W.M., Mazumder, J. and Watkins, K.G. (2003) Laser Material Processing. 3rd Edition, Springer-Verlag, London.

[28]   Pedraza, A.J., Fowlkes, J.D. and Lowndes, D.H. (1999) Silicon Microcolumn Arrays Grown by Nanosecond Pulsed- Excimer Laser Irradiation. Applied Physics Letters, 74, 2322-2324.

[29]   Sanchez, F., Morenza, J.L., Aguiar, R., Delgado, J.C. and Varela, M. (1996). Whiskerlike Structure Growth on Silicon Exposed to ArF Excimer Laser Irradiation. Applied Physics Letters, 69, 620-622.

[30]   Kudryashov, S.I. and Allen, S.D. (2002) Photoacoustic Study of KrF Laser Heating of Si: Implications for Laser Particle Removal. Journal of Applied Physics, 92, 5627-5631.

[31]   Tam, A.C., Leung, W.P., Zapka, W. and Ziemlich, W. (1992) Laser-Cleaning Techniques for Removal of Surface Particulates. Journal of Applied Physics, 71, 3515-3523.

[32]   Park, H.K., Grigoropoulos, C.P., Leung, W.P. and Tam, A.C. (1994) A Practical Excimer Laser-Based Cleaning Tool for Removal of Surface Contaminants. IEEE Transactionson on Components, Packaging and Manufacturing Technology, Part A, 17, 631-643.