Palladium silicide formation under the influence of nitrogen and oxygen impurities

Abstract

The effect of impurities on the growth of the Pd2Si layer upon thermal annealing of a Pd film on 〈100〉 and amorphous Si substrates is investigated. Nitrogen and oxygen impurities are introduced into either Pd or Si which are subsequently annealed to form Pd2Si. The complementary techniques of Rutherford backscattering spectrometry, and 15N(p,α)12C or 18O(p,α)15N nuclear reaction, are used to investigate the behavior of nitrogen or oxygen and the alterations each creates during silicide formation. Both nitrogen and oxygen retard the silicide growth rate if initially present in Si. When they are initially in Pd, there is no significant retardation; instead, an interesting ‘‘snow-plowing’’ effect of N or O by the reaction interface of Pd2Si is observed. By using N implanted into Si as a marker, Pd and Si appear to trade roles as the moving species, when the silicide front reaches the nitrogen-rich region.