Prediction of plasma charging damage during SiO2 etching by VicAddress

We have proposed a prototype of plasma processing CAD, i.e. Vertically Integrated Computer Aided Design for Device processing (VicAddress), that numerically predicts dry etching and related charging damage to a future profile and nanometer scale lower-level elements in ULSI, as well as the low temperature plasma structure. VicAddress has been applied to investigate the dry etching of SiO₂ film, that requires ions with several hundred to a thousand of eV. Negative ion injection to a wafer was numerically predicted and designed in a pulsed two-frequency capacitively coupled plasma (2f-CCP) operated by a VHF (100 MHz) - LF (1 MHz) system. In this paper, we predict the velocity distribution incident on a wafer in a pulsed 2f-CCP by using a Monte Carlo method under the plasma structure given by RCT modeling. We discuss: functional separation of very high frequency sustaining and low frequency biasing sources; the negative charge injection mode to the SiO₂ wafer during etching; and control of excess-dissociation of CFj by high energy secondary electrons.