Selective etching of N-type silicon using pulsed potential anodization

A novel dopant selective etching technique, which uses pulsed anodizing voltages applied to silicon samples immersed in KOH:H/sub 2/O solutions, has been developed. The use of pulsed anodization causes passivation of p-type silicon while n-type silicon continues to etch, making it possible to selectively etch-stop on p-type material. These results are consistent with a process which is rate-limiting by holes in the semiconductor. To demonstrate this technique, a 12 mu m-thick p-type membrane was formed. This method differs from the conventional p-n junction etch-stop in that a diode is not required to accomplish selective anodization and etch-stop. In this way, the performance of the etch-stop does not depend on the presence or quality of the diode.<>