MEASUREMENT AND MODELING OF BORON-DIFFUSION IN SI AND STRAINED SI1-XGEX EPITAXIAL LAYERS DURING RAPID THERMAL ANNEALING

Boron concentration profiles in rapid thermally annealed Si and strained Si1-xGex in situ doped, epitaxial layers were measured using secondary-ion-mass spectroscopy. Comparison of the Si1-xGex samples to the Si samples after rapid thermal annealing revealed a retarded B diffusivity inside the strained Si1-xGex layers. A simple empirical expression for the B retardation, which depended linearly on the Ge concentration, was developed and incorporated into a diffusion model for dopants in heterostructures. This model accurately simulated the measured B concentration profiles over a wide range of Ge fractions (0%-10%), B peak concentrations (2 X 10(18)-3 X 10(19) cm-3), and rapid thermal annealing conditions (900-1025-degrees-C for 20-30 s).