Outdiffusion of Si through gold films: The effects of Si orientation, gold deposition techniques and rates, and annealing ambients

Abstract

Outdiffusion of Si through thin gold films has been studied for (100) and (111) oriented Si wafers in different ambients. The gold films were deposited either by electron beam evaporation or by sputtering, each with two widely different rates. Using air annealings, higher outdiffusion rates of Si are observed for the Au/(100)Si samples than the corresponding Au/(111)Si ones for both deposition techniques, the difference being much more pronounced in the electron beam deposition case; samples with sputtering of gold all show higher outdiffusion rates of Si than their counterparts using the electron beam technique; higher deposition rates of gold also give rise to higher outdiffusion rates of Si, especially for the sputtering case. Similar effects of the Si orientation and gold deposition parameters have also been observed for the samples annealed in N2-O2 mixtures, but with much lower outdiffusion rates of Si than those annealed in air. Several mechanisms are suggested for the effects observed.