Substrate amorphization induced by the sputter deposition process: Geometrical aspects

Abstract

Sputter deposition of thin films and multilayers involves, in the initial stage, the energetic interaction of reflected ions and/or sputter ejected target particles with the substrate surface and with the overlayer-substrate interface.The present work reports on the c-Si(111) surface amorphization when Ge is deposited by 4 keV Ar+ ion sputtering in different experimental geometries. The incidence angle of the Ar+ beam was 65°, with respect to the surface normal, to emphasize prompt collision sputtering. Attempts have been made to clarify the role of the different particles involved in the process. New, unconventional approaches to Auger spectroscopy were used for this study. Substrate structural characterization during overlayer growth has been performed by primary-beam diffraction modulated electron emission (PDMEE) technique, a powerful tool for the investigation of ‘‘buried’’ surfaces. Auger electron kinetic emission from the growing interface was used to determine the occurrence and importance of the different collisional processes. The high average kinetic energy of the Ge atoms ejected from the target in prompt, first-order collisions was found to be responsible for the large substrate amorphization we observed with a specular geometry but not on off-specular geometry. Reflected, energetic Ar+ ions do not play a relevant role.