A model for the etch-stop location on reverse-biased pn junctions

Abstract

This paper reports a model to predict where the silicon anisotropic electrochemical etching terminates on reverse-biased pn junctions. The model explains why the etching process terminates well before the metallurgical junction. The effects of the substrate doping, the type of junction (step or graded), the etching temperature and voltage bias, as well as the technique used (three and four electrodes) are analysed and compared with the experimental data. Some limitations and deviations from this theory are also pointed out.