STRUCTURE-RELATED LOW-FREQUENCY CURRENT FLUCTUATIONS IN POST-DEGRADATION AND POST-BREAKDOWN THIN SILICON OXIDE FILMS

摘要

This paper focuses on the current fluctuation of post-degradation and post-breakdown thin silicon oxide films fabricated by thermal oxidation and sputtering deposition. In light of various characteristics of post-stressed insulating films, the development of a diagnostic technique is challenging. By analyzing current fluctuation spectra after degradation and breakdown, the post-degraded structure of silicon oxide films is characterized. We examine this in greater depth by applying two different observation times and theoretical models to spectral analyses for a thin thermal-oxidation Si0_2 film, and by applying constant voltage stress with current compliance and band-structure models to resistance transition phenomena for a sputter-deposition Si0_2 film. The theoretical models for the current-fluctuation spectra are examined in terms of the experimental analysis. It is demonstrated that the current fluctuation exhibits clear random telegraph noises for a thin thermal-oxidation Si0_2 film, and structure-dependent fluctuation spectra for a sputter-deposition Si0_2 film, in which specific time constants and other important properties are extracted from the fluctuation data. It is shown that the post-degradation and post-breakdown silicon oxide films have different structure-related major traps that contribute to the current fluctuation characteristics. In addition, the possible physical models of the conductive filament and distributions of electron and hole traps are examined experimentally.