Berlin 2015 – wissenschaftliches Programm
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DS: Fachverband Dünne Schichten
DS 26: Layer Properties: Electrical, Optical, and Mechanical Properties
DS 26.8: Vortrag
Mittwoch, 18. März 2015, 17:00–17:15, H 2032
Nitrogen concentration dependence of the stiffness of silicon nitride layers formed by low-dose N+ ion implantation — •Marina Sarmanova1, Helmut Karl2, Stephan Mändl1, Dietmar Hirsch1, Stefan G. Mayr1,3, and Bernd Rauschenbach1,3 — 1Leibniz Institute of Surface Modification, D-04318 Leipzig, Germany — 2University Augsburg, Institute of Physics, D-86135 Augsburg, Germany — 3University Leipzig, Institute for Experimental Physics II, D-04103 Leipzig, Germany
Si wafer material was implanted at room temperature with 100 keV N+ ions at fluences between 1 * 10^15 and 1 * 10^17 cm^-2. Sub-stoichiometric SiNx layers were formed in the near-surface region. Subsequent thermal annealing was performed at 800°C in three half-hour steps. Elastic properties of implanted layers were measured nanometer-resolved by contact resonance atomic force microscopy (CR-AFM) as function of ion fluence after each annealing step. Strong correlation between the nitrogen content and the indentation moduli was observed while recovering defects caused by the implantation inside the material. The determined indentation moduli range between 100 and 180 GPa depending on the annealing duration and nitrogen content. Reduction of the indentation moduli of as-implanted samples is caused by the implantation induced amorphization. Long-term annealing led to the increase of the indentation moduli of the high-fluence implanted Si wafers over the value of indentation modulus for crystalline silicon material (165 GPa). The high indentation moduli can be explained by formation of Si-N bonds verified by X-ray photoelectron spectroscopy.