Competitive delineation of n- and p-doped Si by selective electrochemical etch

We present a detailed experimental investigation of the simultaneous selective electrochemical etch of arsenic and boron doped regions in silicon. We used different chemical solutions containing HF and/or HCl. The etching selectivity is evaluated in calibration samples, implanted with As and/or B, by comparing the topography of the etched surface, analyzed by transmission electron microscopy, with the carrier concentration profiles, measured by spreading resistance profiling. We demonstrate the capability of tuning the selectivity of the two different dopant species by changing the chemical solution used in the electrochemical cell. We also present an application demonstrating the high sensitivity that we achieve in delineating weakly boron-doped regions in a silicon device.