Methods of fabricating semiconductor devices having protected plug contacts and upper interconnections

Abstract

Embodiments of methods of fabricating protected contact plugs include forming an electrically insulating layer having a contact hole therein, on a semiconductor substrate and then forming an electrically conductive lower barrier layer that lines at least an upper portion of a sidewall of the contact hole. This lower barrier layer may comprise titanium nitride (TiN). A step is also performed to form an electrically conductive contact plug that extends in the contact hole, is electrically coupled to the lower barrier layer and protrudes above the electrically insulating layer. The contact plug may comprise tungsten (W). An electrically conductive upper barrier layer is then formed that extends on a protruded upper surface of the contact plug and on a surface of the lower barrier layer. A step may then be performed to pattern the upper barrier layer to define an electrically conductive barrier spacer that extends on a sidewall or end of the lower barrier layer and define an upper barrier layer cap on the protruded upper surface of the contact plug.