Method to prepare hemi-spherical grain (HSG) silicon using a fluorine based gas mixture and high vacuum anneal

A process for forming hemi-spherical grained silicon capacitor plates, said process comprising the steps of:

• forming an amorphous silicon layer over a pair of neighboring parallel conductive lines, said amorphous silicon layer making contact to an underlying conductive region;
• patterning said amorphous silicon layer to form individual silicon capacitor plates;
• and
• exposing said silicon capacitor plates to a fluorine based gas mixture during an annealing period, thereby transforming said silicon capacitor plates into said hemi-spherical grained silicon capacitor plates, wherein said fluorine based gas mixture is a gas mixture selected from the group consisting of NF.sub.3, CF.sub.4, and C.sub.2 F.sub.4 Cl.sub.2.

A process for forming hemi-spherical grained silicon storage capacitor plates, said process comprising the steps of:

• forming an amorphous silicon layer over a pair of neighboring parallel conductive lines, said amorphous silicon layer making contact to an underlying conductive region;
• patterning said amorphous silicon layer to form individual silicon capacitor plates;
• exposing said silicon capacitor plates to a fluorine based gas mixture during an high vacuum annealing period, thereby transforming said silicon capacitor plates into said hemi-spherical grained silicon capacitor plates, said fluorine based gas mixture is a gas mixture selected from the group consisting of NF.sub.3, CF.sub.4, and C.sub.2 F.sub.4 Cl.sub.2 ;
• conductively doping said hemi-spherical grained silicon capacitor plates;
• forming a capacitor dielectric layer adjacent and coextensive said hemi-spherical grained silicon capacitor plates;
• and
• forming a second conductive silicon layer superjacent and coextensive said capacitor dielectric layer.