Study of doping dependent p-n junction etch-stop using pulsed electrochemical anodization

Experiments on a new selective etching method using pulsed potential anodization of p (10-15 ohm-cm) on 10-13 ohm-cm n-type (100) silicon wafers immersed in KOH/Hsub2O solution showed that etching stops several microns before the metallurgical p-n junction is reached. Electrical simulations of the forward biased p-n junction by PICES-2B feature a strong dependence between the diffusion length of holes and the remaining n-type materil on p-type silicon. To demonstrate this, several wafers with different carrier concentrations were etched successfully. This method offers the possibility of adjusting the thickness of p-type silicon membranes by a variation of the carrier concentration for p- as well as for n-type silicon.