Shallow diffusion profile analysis of phosphorus in silicon at 1100 °C and an empirical fit

A detailed study of a phosphorus diffusion profile in silicon at 1100 °C was made by repeated removal of silicon layers and resistivity measurements by observing the limitations of four-point probe voltage and currents [Solid-State Electron. 25, 611 (1982)]. The results confirmed that the phosphorus diffusion profile is not always given by an error function and on the contrary, a distinct kink and tail structure occurs in the profile. The observed data seems to agree with the concept of two diffusion coefficients proposed by Tsai [Proc. IEEE 57, 1499 (1969)] for temperatures below 1100 °C. Observed experimental data have been analyzed to give the values of the two diffusion coefficients and an empirical fit has been found. It is pointed out that two independent Gaussian profiles can be fitted for the phosphorus profiles by the two diffusion coefficients which lead to the apparent kink and tail structure of the profile.