Method to prevent volcano effect in tungsten plug deposition

摘要

A method to prevent volcano effect in tungsten plug deposition is described. The method is applied to both the contact plugs as well as the via plugs. For these purposes, the use of a nitrogen (N2) plasma of a specific recipe is introduced. It is shown that the presence of the nitrogen plasma improves the titanium nitride (TiN) barrier layer through annealing, and nitrogen stuffing of the grain boundaries. In addition, a titanium (Ti) layer must be used prior to the deposition of the TiN layer in order to improve adhesion. This step also enhances the titanium nitride barrier, and reduces the contact resistance (Rc) of the contact-plugs as well. Finally, the nitrogen plasma process and the metal deposition can be done in one and the same equipment.