A novel technology to reduce the antenna charging effects during polysilicon gate electron-cyclotron-resonance etching

A novel technique, which uses Cl/sub 2//O/sub 2/ mixed gas in the electron cyclotron resonance (ECR) etching system, has been proposed to remove the antenna charging effect of the MOS capacitors with 5-nm-thick oxides during polysilicon gate etching. The Cl/sub 2//O/sub 2/ can cause the trenching effect and prevents the gate oxide from the charging damage. Furthermore, the ECR system can provide high polysilicon/oxide selectivity so that the Si substrate under gate oxide is not directly bombarded by the ions. Consequently, the E/sub bd/ degradation of the MOS capacitors disappears as the trenching effect is apparent by using moderate Cl/sub 2//O/sub 2/ mixed gas.