Modeling of Germanium/Silicon Interdiffusion in Silicon/Silicon Germanium/Silicon Single Quantum Well Structures
M. Hasanuzzaman and Y.M. Haddara
McMaster University, CA
SiGe, diffusion, interdiffusion, modeling, heterostructures, process modeling
Intermixing at heterointerfaces and the broadening of the SiGe layer in a Si/SiGe/Si single quantum well (SQW) structure can be detrimental to device performance. Thus it is important to develop predictive models for interdiffusion phenomena in heterostructures. In this work, the vacancy flux model [1, 2] is implemented using the FLOOPS-ISE process simulator and used to simulate previously published data  on Si-Ge interdiffusion in Si/Si0.85Ge0.15/Si SQW structures grown by MBE and annealed at 900°C, 1000°C, and 1100°C in inert and oxidizing ambients. Our implementation of the model takes into account the conservation of lattice site density to relate the vacancy flux to the flux of the two diffusing species. We also account for the dependence of the intrinsic equilibrium vacancy concentration (CV*) and the intrinsic diffusivities of Si and Ge on the Ge fraction. We fitted values of the intrinsic diffusivities as a function of Ge fraction to match the inert diffusion profiles. Once these values were fixed, the diffusion behavior under oxidizing conditions was completely accounted for by the model with no additional fitting parameters.
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Nanotech 2005 Conference Program Abstract