Direct experimental measurement techniques have had limited success in the determination of the two-dimensional (2D) doping profile of a MOSFET. In this paper, we describe an alternative methodology that uses source/drain (S/D) diode and gate overlap capacitance measurements to determine the 2D profile by inverse modeling [l]. Our approach is based on the optimized tensor product spline (TPS) representation of the profile. We use nonlinear multiple outputs, least squares optimization to extract the values of the B-splines coefficients.