In order to make predictive models of transition metal gettering during sem
iconductor processing, a complete understanding of the process variables in
high temperature ranges is essential. These variables are the internal get
tering site density and capture radius, the intrinsic metal solubility, sil
icon doping level, the band gap, the effective density of states of the con
duction and valence bands, and the transition metal defect level position i
n the gap. The least understood of these parameters is the temperature depe
ndence of the transition metal defect level position. The work of Gilles et
al. and McHugo ct al. demonstrates that the doping enhancement of the solu
bility of Fe in p-type silicon vanishes at temperatures above 1000 degrees
C. They model this behavior by proposing movement at high temperature of th
e defect level for interstitial Fe from within the energy gap into the vale
nce band. We explore the available models for Si effective density of state
s as a function of temperature and generate a third density of states model
based on 0 It ab initio band structure calculations with the temperature-a
ppropriate carrier occupations given by Fermi-Dirac statistics. We also con
sider uncertainty in E-G in the processing temperature regime. We show that
uncertainties in the Si intrinsic properties database in the processing te
mperature regime can account for the available dopant-enhanced solubility d
ata by assuming that E-tau remain at a constant fraction of E-G. To quantit
atively model gettering processes at high temperatures, more reliable estim
ates are needed for the densities of states of the conduction and valence b
ands, E-G and the behavior of defect levels as temperature rises. (C) 1999
Elsevier Science B.V. All rights reserved.