Nondestructive One- and Two-Dimensional Doping Profiling by Inverse Methods

摘要

For semiconductor device characterization, knowledge of the distribution of the doping atoms in the semiconductor material--the doping profile--is important. Electrical measurements are an attractive, nondestructive way of determining the doping profile. Both capacitance-voltage (CV) and channel conductance measurements are suitable for this purpose. However, limits are imposed on the accuracy and application range of electrical measurements due to the restrictions of the classical measurement data interpretation methods, such as Schottky's CV formulas. To overcome these limitations, two related numerical methods for the interpretation of electrical measurement data are proposed and applied. They have been derived by regarding the determination of the doping profile as an inverse problem; analogies with inverse problems from geophysics and biophysics are then easily found. Both numerical methods rely on the minimization of at least squares error sum of the difference between the measured and simulated electrical characteristics of the device.