Reliability characteristics of metal-oxide-semiconductor capacitors with chemical vapor deposited Ta2O5 gate dielectrics

Abstract

This letter discusses the reliability characteristics of metal-oxide-semiconductor capacitors with chemical-vapor-deposited Ta2O5 gate dielectric films. To be compatible with the conventional polycrystalline Si-gate process, SiO2 or Si3N4 film was deposited on Ta2O5 as the top dielectric layer. It is found that under high-field stress, interface state generation is enhanced with the presence of the top dielectric layers, probably due to the anode-field increase caused by the positive-charge buildup in the stacked dielectrics capacitors. The significant positive-charge build-up in capacitors with top dielectrics is believed to be due to the hole-injection-barrier from Ta2O5 to SiO2 or Si3N4 and/or damage creation in the Ta2O5 films.