A comprehensive assessment of microtrenching during high density polysilicon etch

We have used a modified MOS capacitor (MMOS) to assess microtrenching during the polysilicon gate etch process. We demonstrate for the first time that microtrenching can result in device parametric and reliability failures. The linear drive current and transconductance degrade by 60% with severe microtrenching. The channel hot carrier lifetime was also lower by several decades when compared with moderately microtrenched devices. We have quantified the feature dependence of microtrenching by high density ICP etch, and observe enhanced microtrenching in nested lines due to additional reflections.