Analytical electron microscopy study of nanometre-scale oxide formed in contact-hole-bottom Si surfaces.

Nanometre-scale interfacial oxides formed in contact-hole-bottom Si surfaces were investigated by analytical electron microscopy coupled with a field-emission transmission electron microscope. The results showed that the chemical state of the residual oxide formed during reactive-ion etching was mostly changed from the suboxide of Si2+ or Si3+ to the oxide of Si4+ by the following light-etch treatment. Consequently, the process of removing the residual oxide by light-etch treatment was improved and it contributed to the accomplishment of lower contact resistance.