Plasma-Induced Defect-Site Generation in Si Substrate and Its Impact on Performance Degradation in Scaled MOSFETs

Abstract

Plasma-induced ion-bombardment damage was studied in terms of defect sites created underneath the exposed Si surface. From the shift of capacitance-voltage ( <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">C</i> - <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">V</i> ) curves, the defect sites were found to capture carriers (being negatively charged in the case of an Ar plasma exposure). This results in a change of the effective impurity-doping density and the profile. We also report that the defect density depends on the energy of ions from plasma. A simplified and quantitative model is proposed for the drain-current degradation induced by the series-resistance increase by the damage. The relationship derived between the defect density and the drain-current degradation is verified by device simulations. The proposed model is useful to predict the device performance change from plasma process parameters.