A model for the etch stop location on reversed biased pn junctions

This paper reports a model to predict accurately where the silicon electrochemical etching terminates on a reversed biased pn junction. One of the most suitable and successful etch stop techniques is the electrochemical etch stop (ECES), achieved by reverse biasing a pn junction. Although it has been expected, it is clear from published results that the ECES does not terminate at the metallurgical junction. In most applications, accurate control of the obtained membrane thickness is compulsory. Therefore, the understanding of the premature stop of the etching process and the prediction of its exact location is of major importance in the MEMS field