Nanoanalytical Characterization of Breakdown Spots in Ultrathin Gate Dielectrics

The electrical properties of breakdown spots in ultrathin gate dielectrics are studied using a newly developed percolation path resistance measurement method [1]. Post-breakdown characterization of the nanometer size breakdown path shows that the breakdown path degrades rapidly during the initial stage of progressive breakdown, and exhibit Schottky-like characteristics in poly-Si/SiNxOy, poly-Si/HfO2and TiN/TaN/HfO2gate stacks. Physical and chemical analysis using transmission electron microscopy provides useful information about the nature of the breakdown induced defects. In order to better characterize the breakdown path within the gate dielectrics matrix, we propose to use ultrahigh energy resolution monochromator-based transmission electron microscopy. This technique allows us to study the chemistry and electronic structures of the percolation path itself, and the percolation path/Si substrate interface and the percolation path/gate electrode interface. The ultimate goal is to understand the materials and electrical properties, and chemistry of breakdown paths in advanced gate stack structures at atomic resolution.