Charge trapping/generation and reliability for high-performance tantalum oxide capacitors

Charge trapping/generation behavior and reliability of recently developed high-performance sputtered/anodized tantalum oxide films in structures of Al-tantalum-oxide-Ta metal-insulator-metal (MIM) capacitors under constant current stress are studied by observing the voltage-time and time-to-breakdown characteristics in comparison with those of the usual tantalum oxide MIM capacitors prepared by either anodization or reactive sputtering. The dominant charge trapping/generation in the anodized tantalum oxide films is either slow electron trapping under current stress on the Ta bottom electrodes or positive charge generation under current stress on the Al top electrodes. Positive charge generation due to oxygen vacancies after fast electron trapping is dominant in the sputtered tantalum oxide films which show defect-related breakdown phenomena. The sputtered/anodized tantalum oxide demonstrates much superior reliability because of its less charge trapping/generation and better enduring property under charge injection compared with the anodized or the sputtered tantalum oxide films.