METHOD AND APPARATUS FOR ANISOTROPIC TUNGSTEN ETCHING

摘要

Methods for anisotropically etching a tungsten-containing material (such as doped or undoped tungsten metal) include cyclic treatment of tungsten surface with Cl2 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 Cl2 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 a presence of dielectric materials such as silicon oxide, silicon nitride, and silicon oxynitride.

主权项

1. A method of anisotropically etching a tungsten-containing material on a semiconductor substrate in a plasma etching apparatus, the method comprising:
(a) providing a semiconductor substrate comprising a tungsten-containing material to a plasma etching process chamber; (b) introducing a first process gas comprising Cl2 to the plasma etching process chamber and forming a plasma to react the tungsten-containing material with a plasma-activated chlorine; (c) removing the first process gas from the plasma etching process chamber after (b); (d) introducing a second process gas comprising an oxygen radical source to the plasma etching process chamber and forming a plasma comprising oxygen radicals to passivate a surface of the tungsten-containing material and thereby form a passivation layer comprising a compound that includes tungsten and oxygen; and (e) removing the second process gas from the plasma etching process chamber after (d), wherein the method predominantly etches the tungsten-containing material in a selected direction.