STRONG EFFECT OF DOPANT CONCENTRATION GRADIENT AN ETCHING RATE

Dopant concentration sensitive etching of silicon in HF:HNO3:CH3COOH s olution was studied using epitaxially grown silicon samples. The study has shown the unstable character of the process, significant time and structure size dependencies of the etching rate, as well as the depen dence of the rate on the dopant concentration gradient. The data may b e rationalized on the basis of the electrochemical and autocatalytic n ature of the reaction. The influence of the dopant gradient and overal l device geometry on the etching rate may cause significant inaccuracy of the dopant distribution measurements. (C) 1998 American Vacuum Soc iety.