Lattice diffusion of boron in bulk cobalt disilicide

Abstract

The lattice diffusion of boron implanted in cobalt disilicide (CoSi 2) has beenstudied. The bulk COSi 2 substrate, prepared by solidification from a melt, has grain sizes in the millimetre range, thus minimizing the interference from grain boundary diffusion. Boron was introduced into the COSi 2 substrate by ion implantation, and after heat treatments ranging from 450 °C to 700 °C the boron distribution was monitored by secondary ion mass spectrometry. The diffusion coefficient was determined from the shape of the resulting boron profile by means of a numerical fitting procedure where the actual shape of the as implanted profile was taken into account. An activation energy of 2.1 eV was found for the lattice diffusion of boron in COSi 2, and the lattice diffusion coefficient can be represented in an Arrhenius form as: D lattice e = 0.9 exp (−2.1/ kT) * cm 2 s −1.