| 摘要 |
Methods for anisotropically etching a tungsten-containing material (such as doped or undoped tungsten metal) include cyclic treatment of tungsten surface with Cl_2 plasma and with oxygen-containing radicals. Treatment with chlorine plasma is performed while the substrate is electrically biased resulting in predominant etching of horizontal surfaces on the substrate. Treatment with oxygen-containing radicals passivates the surface of the substrate to etching, and protects the vertical surfaces of the substrate, such as sidewalls of recessed features, from etching. Treatment with Cl_2 plasma and with oxygen-containing radicals can be repeated in order to remove a desired amount of material. Anisotropic etching can be performed selectively in the presence of dielectric materials such as silicon oxide, silicon nitride, and silicon oxynitride. |
