ECV Doping Profile Measurements in Silicon Using Conventional Potentiostat

Abstract

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.