ECV Doping Profile Measurements in Silicon Using Conventional Potentiostat

摘要

Formation of p-n junctions by phosphorus diffusion from liquid dopant in Si was investigated using a custom-built procedure for performing electrochemical capacitance-voltage (ECV) measurements. The feasibility of using a potentiostat equipped with an impedance module was investigated using an algorithm and experimental setup developed for the ECV technique. Using impedance spectroscopy and amperometry methods in a controlled manner, the dopant concentration was measured in the depth range of 600 nm to 900 nm. Sequential etching in NH4F (0.1 M) electrolyte using current-time (I-t) testing under ultraviolet (UV) illumination was applied to etch the surface of n-type silicon and estimate the diffusion depth. Initial current-voltage (I-V) tests were used to determine the bias voltage. The results of the proposed method were compared with those obtained using a commercially available ECV profiler. A conventional parallel equivalent circuit model of the Schottky junction was used to describe the electrolyte-silicon barrier, leading to good agreement between the proposed method and commercial ECV analysis results.