Boundary effect in electrochemical etching of silicon

Specific features of electrochemical etching near the boundary delimiting the region in which the wafer contacts with electrolyte are analyzed for the example of macropore formation in n-and p-type silicon. It is shown that the boundary effect consisting in accelerated etching of silicon near the mask edge depends on geometric parameters of the cell and has common features both in etching of n-Si with the wafer backside illuminated and in etching of p-Si without illumination. Methods for eliminating the boundary effect are suggested.