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Invited review for Materials Science in Semiconductor Processing 8/16/99 Stress Effects on Defects and Dopant Diffusion in Si
 

Summary: Invited review for Materials Science in Semiconductor Processing 8/16/99
Stress Effects on Defects and Dopant Diffusion in Si
Michael J. Aziza)
Division of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138
ABSTRACT
The effects of stress on equilibrium point defect populations and on dopant diffusion for single
crystals free of extended defects are reviewed. The thermodynamic relationships presented permit the
direct comparison of hydrostatic and biaxial stress experiments and of atomistic calculations under
hydrostatic and nonhydrostatic stress for any proposed mechanism. Experiments on the effects of
pressure and stress on the diffusivity are reviewed. For Sb in Si, using as input the measured effect
of hydrostatic pressure on diffusion and the assumption of a pure vacancy mechanism, the measured
effect of biaxial stress on diffusion can be predicted successfully with no free parameters. For B in
Si, an apparent discrepancy between the hydrostatic and biaxial stress effects exists assuming a pure
interstitial-based mechanism. The requirements to permit the prediction of the effect of an arbitrary
stress state on diffusion in an arbitrary direction are discussed.
INTRODUCTION
Because understanding and controlling diffusion-related phenomena become increasingly
important as semiconductor device dimensions decrease, diffusion in Si has been heavily studied [1].
For bandgap engineering purposes, biaxial strain is designed into certain epitaxial semiconductor
devices, e.g. heterojunction bipolar transistors for high-power and high-speed applications such as

  

Source: Aziz, Michael J.- School of Engineering and Applied Sciences, Harvard University

 

Collections: Physics; Materials Science