Growth and alignment of gold silicide islands on br-passivated vicinal si(111) surfaces

Abstract

Growth of gold silicide islands on bromine-passivated Si(111) substrates have been studied by Rutherford backscattering spectrometry, optical microscopy, scanning electron microscopy and energy dispersive X-ray analysis. Formation of epitaxial gold silicide islands were observed when Au thin films, deposited on bromine-passivated Si(111) substrates, were annealed at temperatures close to the Au---Si eutectic temperature and above. The silicide islands mainly grow in equilateral triangular or trapezoidal (or rod-like) shape. The rod-like islands of uniform width have an aspect ratio as large as 15:1. The island edges are aligned along the substrate [11^-0], [011^-] and [1^-01] directions. The large trapezoid (or rod)-shaped islands have been found to be aligned along one of the three equivalent {1 0} directions. The substrate surface normal was 4° misoriented from the [111] direction towards the [1^-1^-2] azimuthal direction. The aligned growth of large islands is attributed to the vicinality of the substrate. The Br-passivated substrates were prepared by a chemical method and Au film deposition and annealing were performed under high vacuum. The composition and the general features of growth of the silicide islands are comparable to those obtained under UHV conditions.