Comparison of Dry Development Techniques using O2 and SO2/O2 Low-Pressure Plasmas

A parametric study of the pattern transfer step in a trilevel resist system using oxygen-based plasmas has been performed using a distributed electron cyclotron resonance reactor with independent rf biasing. In pure oxygen plasmas, critical dimension loss is always present. The mechanisms most likely to be responsible for these defects during the pattern transfer process are presented and discussed. A novel plasma etching process based on sidewall passivation by sulfur is proposed using SO2/O2 mixtures. Perfect anisotropy with negligiable critical dimension loss is obtained at room temperature.