Physical Processes Associated with Radiation-Induced Interface States.
HARRY DIAMOND LABS ADELPHI MD
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The buildup of interface states in Al-Si02-Si metal oxide semiconductor capacitors following exposure to pulsed electron beam irradiation has been previously shown to be a two-stage process. In the present work, we further examined the buildup by varying the polarity and magnitude of the field across the oxide during the two stages of the buildup. Specifically, both early .000001 to 1 s and late 1 to 10000 s time regimes are explored. An empirical model of radiation-induced interface states at the Si02Si interface is presented. The formulation, which explicitly addresses the time-dependent two-stage nature of the buildup process, gives the mathematical dependencies of the experimentally observed buildup on time, field, temperature, and dose. Along with the results of the field-switching experiments, the implications of the empirical model for the microscopic mechanisms involved in the buildup are discussed. In particular, the first stage is attributed to positive ion release in the bulk of the oxide via interactions with radiation-generated holes. The second stage is then associated with the transport of the liberated ions to the Si02Si interface for positive gate bias where a subsequent interaction results in the appearance of electrically observable interface states. The experimental results and model are compared to and interpreted in light of recent related work in the literature.
- Physical Chemistry
- Electrical and Electronic Equipment