Abstract
A set of equations describing a stress-mediated evolution of the nonequilibrium dopant-defect system has been derived and analyzed. Together with coupled diffusion of dopant atoms and point defects, we consider the drift of all mobile species in different charge states, namely vacancies, self-interstitials, and pairs “dopant atom–point defect”, in the field of stress. It has been shown that stresses may affect the diffusion of dopant atoms mainly in two ways: (1) directly, due to the drift of the pairs in the field of stress; (2) indirectly, by the formation of nonuniform defect distribution due to the drift of point defects. On this basis, various features of doping processes, such as phenomena of “uphill” impurity diffusion near the surface (within the framework of the first or second mechanisms) and the peculiarities of high concentration phosphorus diffusion (due to the second mechanism), can be explained. Numerical computations of high concentration phosphorus diffusion in silicon and transient-enhanced diffusion of ion-implanted arsenic have been carried out, and parameters of diffusion have been extracted. The calculated dopant profiles agree well with the experimental data. The set of equations obtained is applicable to modeling of diffusion in the layers with nonuniform stress distribution arising due to high concentration of dopant atoms, lattice mismatch, etc.
Published Version
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