An investigation was made of the phenomenology of boron-rich layer formation, which resulted from BBr3 boron diffusion processes, and of its impact upon sheet resistance and bulk lifetime. The measurements showed that boron silicate glass and boron-rich layer thicknesses varied from 50 to 600nm and from 0 to 80nm, respectively, within the two-dimensional wafer surface of one sample, for one diffusion process. Both thicknesses depended strongly upon the gas composition during the composition and deposition time. Further results showed that boron-rich layer formation was favoured by high concentrations of BBr3 vapour and of oxygen during B2O3 deposition. High drive-in temperatures also promoted growth of the boron-rich layer.

Charge Carrier Lifetime Degradation in Cz Silicon through the Formation of a Boron-Rich Layer During BBr3 Diffusion Processes. M.A.Kessler, T.Ohrdes, B.Wolpensinger, N.P.Harder: Semiconductor Science and Technology, 2010, 25[5], 055001