PROFILE CONTROL OF POLY-SI ETCHING IN ELECTRON-CYCLOTRON-RESONANCE PLASMA

Recent studies of plasma etching indicate that high-density charge irradiation easily induces radiation damage and local side etch. The local side etch has a characteristic dependence on the pattern layout and plasma conditions. The local side etch observed in poly-Si patterns with various widths of outside space increases with higher electron temperature perpendicular to the surface normal (T-ev) and higher ion current density. The rf bias method is effective for reducing local side etch. However, elimination of side etch with rf bias is due to an increased in ion energy. Thus high selectivity and no local side etch cannot be achieved at the same time. The local side etch with rf bias depends on electron temperature. Lower T-ev is effective for reducing the side etch even in the biased process.