Interaction of evaporated palladium and titanium films with single-crystal silicon

Abstract

Silicide formation with electron-gun-evaporated films of titanium and palladium was studied using MeV 4He + backscattering spectrometry, glancing angle X-ray diffraction and scanning electron microscopy. For samples with the structure (single-crystal) Si/Pd/Ti it was found that titanium silicides grew on top of Pd 2Si at temperatures above 500 °C. For the temperature range 530–650 °C the growth rate of this titanium silicide layer on 〈111〉-oriented substrates was compared with that observed for titanium films evaporated directly onto 〈111〉 silicon; it was found that the growth rates were highest when an interposing palladium layer was present. For samples with the structure 〈100〉 Si/Pd/Ti annealing at above 550 °C yielded very laterally non-uniform layers. A model for this phenomenon is presented. Samples with the structure 〈100〉 Si/Ti/Pd yielded compound formation between the titanium and the palladium and no observed silicide formation (after annealing at 550 °C for 30 min) when the ratio Ti:Pd was greater than 1:1. Samples with a Ti:Pd ratio of about 1:3 gave laterally non-uniform silicide formation (after annealing at 550 °C for 30 min).