Simulation of SiGe Epitaxial Growth for RF-Bipolar Transistors
A simple simulation model for the in-situ doped chemical vapor deposition of Si1-xGex-epitaxial layers is presented that enables the calculation of the germanium and base doping profiles of modern rf-bipolar transistors from the process recipe, i.e. gas flows, deposition time and temperature. A first approach is based on the interpolation of experimental data characterizing the CVD-equipment. Although this gives already very good results for slowly varying GeH4-flows, abrupt turn-offs of the gas flow result in too steep profiles as compared to experiments. An extension of the model is presented that solves this problem via the introduction of a germanium surface layer that feeds a slowly decaying germanium concentration in the deposited silicon even after the germane flow has been turned off.
KeywordsTCAD Simulation Simple Simulation Model Steep Profile Process Recipe Simple Rate Equation
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