ECR PLASMA-ETCHING WITH HEAVY HALOGEN IONS

It is shown that the ECR plasma, which contains heavy halogen ions and other light ions, is effective as a dry etching technique for fabrication of VLSI devices. The ion temperature, which is one of the most important parameters for etching fine features, is greatly reduced by using a Cl2/He mixture gas and by controlling the pressure. By this method, strong anisotropic etching of poly-Si is realized with high selectivity to SiO2. Hydrogen halide gases are suitable gases for the ECR plasma etching process, because they produce heavy halogen ions and protons. In particular, using HBr or HI gas produces a strong anisotropic feature with no micro-loading effects. The ion temperature of Br+ions and I+ions is 1.0∼1.1 eV, which is about half that of Cl+ions. © 1990 IOP Publishing Ltd.