Profile Estimation of High-Concentration Arsenic Diffusions in Silicon

In order to facilitate surface concentration estimation for arsenic diffusion, a simple expression has been derived which is dependent only upon the junction depth x_J and the sheet resistance R_s: C_s = 1.56 × 10¹⁷/x_JR_s. This equation was derived from experimental mobility data and a polynomial approximation to the solution of the arsenic diffusion equation. Available data on diffusions carried out from five different kinds of arsenic sources indicate that this derived equation for C_s is accurate to within 15% for $C_s\mathrm{\gtrsim ni}$ .