A new and holistic modelling approach for impact of line-edge roughness on dielectric reliability

Abstract

A new and holistic modelling methodology is developed to investigate the impact of line-edge roughness (LER) on time-dependent dielectric breakdown (TDDB). Unlike the conventional approach with a normal distribution for LER profiles [1-3], a realistic simulation of line-edge roughness (LER) profiles is carried out based on a power-spectrum density (PSD) function including the effects of both roughness and correlation-length (σ and λ). In contrast to the previous work, we show that LER roughness causes a significant reduction not only in T63 (scale parameter) but also in β (shape parameter). While our results show that the thickness dependence of T63 and β with LER follows a similar trend of the conventional percolation model, unlike porosity effect introduced in conventional percolation model the effective defect size (a 0 ) is found to increase with increasing roughness (σ). To examine the strong impact of larger roughness on TDDB, a field-enhancement effect is included in LER modelling. Although the impact of field-enhancement due to protrusions on TDDB has been qualitatively discussed in the past, our LER simulation with a statistical approach has achieved quantitative agreement with experimental data, revealing an in-depth knowledge for the separate roles of LER profiles and field-enhancement. Thus, our methodology can be implemented as a realistic reliability assessment tool for technology qualification.