Application of dynamic ion mixing in platinum silicide formation

Abstract

Results concerning platinum silicide formation by dynamic mixing (ion mixing during Pt film deposition) are presented. The influence of ion beam irradiation on the growth kinetics of a platinum silicide layer formed by vacuum deposition of Pt atoms and simultaneous ion irradiation was investigated. The Pt atoms were deposited onto silicon substrate (both crystalline and amorphous) during 150 keV energy Ar + ion irradiation. Temperature of the substrate during deposition was varied from 300 to 800 K, Pt atom flux was equal to 2 x 10 14 cm -2 s -1, ion beam flux density varied from 5 x 10 11 to 6 x 10 12 cm -2 s -1 (ion dose 10 15-1. 1 x 10 16 cm -2). After deposition the Pt-Si structures were ennealed at temperatures in the range 400–1300 K. The composition of the deposits (as-deposited and annealed at 400–1300 K) was investigated by means of Rutherford backscattering spectroscopy, the structure of the Pt-Si system was studied by X-ray diffraction. A linear dependence of the reacted Pt 2Si layer thickness on the ion flux density (or ion dose) was found if deposition was conducted at room temperature on crystalline silicon. Dynamic mixing at elevated substrate temperatures (400–700 K) causes formation of a thermally unstable inhomogeneous layer consisting of Pt 2Si and silicide with excess of Pt. If dynamic mixing is provided at temperature 800 K and higher direct PtSi layer formation is possible.