Diffusion of Gold in Silicon

Abstract

The spreading resistance technique has been used to measure the degree of resistivity compensation in NTD‐Si samples following Au diffusion under many different conditions. From the theoretical curves of Thurber and Bullis (1) these can be converted to substitutional Au concentration distributions, Cnormals . Several new effects have been found, all of which can be interpreted using the “kick‐out” mechanism, whereby Au atoms enter substitutional sites by removing an Si atom that becomes a self‐interstitial, I . The Au diffusion process is then controlled entirely by the local concentration, CI , and out‐diffusion of these self‐interstitials. Detailed analyses and numerical solutions of the diffusion equations are given, and the experimental results can all be fitted, for instance, at 845°C using an Si self‐interstitial diffusion constant DI≧3×10−7 cm2 sec−1 . The time dependence of CS is also explained. For the first time, direct evidence for the very rapid diffusion of interstitial gold, Aunormali , is presented. It is shown that Dnormali≧10−5 cm2 sec−1 and that the equilibrium concentration of Aunormali is probably greater than or equal to the equilibrium concentration of substitutional atoms, AuS . The effect of swirl defects on Au diffusion is also demonstrated and explained.

Real-time observation of self-interstitial reactions on an atomically smooth silicon surface

“…Thus, the boundary conditions in equation (9) can be replaced by Dirichlet-type with the respective equilibrium concentration for Aui. According to our calculations, this change in the boundary conditions will result in a symmetric U-shaped concentration profile of gold diffusing from the surface as previously reported [70][71][72]. This means that Dirichlet-type boundary conditions for Aui are useful for the correct simulation of long-duration gold diffusion in silicon, whereas initial depth profiles of native point defects and impurity concentrations form at the start of metal diffusion and are determined by equation (9).…”

Modeling of the Surface Annihilation of Excess Self-Interstitials Generated by Gold Diffusion into Silicon

“…Hill et al [7] have found that I annihilation at bare Si surfaces is faster than that at Au-deposited surfaces. In contrast, I-annihilation velocities at Si surfaces capped by oxide or nitride layers (cf.…”

“…In contrast to most previous studies, the boundary condition of self-interstitials was formulated in terms of a limitation on the (reduced) fluxes J 1 through both surfaces (cf. [7]), i.e.,…”

Bergauf‐Diffusion des Phosphors im Silizium

“…Erst nach dem Erreichen der Diffusionstemperatur wurde dem 02-Strom das N,-POCl,-Gemisch hinzugefugt. Dabei wurde der N,-Strom (20 l/h, ebenfalls bei 25°C gemessen) gleichbleibend rnit POC1, bei 25 …”