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

A method of forming an integrated circuit memory device, comprising the steps of:

• forming first and second word lines on a semiconductor substrate;
• forming a lower contact plug that extends on the substrate and is self-aligned to the first and second word lines;
• forming an interlayer insulating layer having a contact hole therein that exposes the lower contact plug, on the substrate;
• forming an electrically conductive lower barrier layer that lines at least an upper portion of a sidewall of the contact hole;
• forming an electrically conductive intermediate contact plug that extends in the contact hole, is electrically coupled to the lower contact plug and protrudes above a major upper surface of the interlayer insulating layer;
• forming an electrically conductive upper barrier layer that extends on a protruded upper surface of the intermediate contact plug and on a surface of the lower barrier layer;
• forming a metal layer on the upper barrier layer;
• and
• patterning the metal layer and the upper barrier layer to define a bit line that is spaced from the protruded upper surface of the intermediate contact plug by a portion of the upper barrier layer and define an electrically conductive barrier spacer that extends on a surface of the lower barrier layer.

A method of forming a conductive contact via, comprising the steps of:

• forming an electrically insulating layer having a contact hole therein, on a semiconductor substrate;
• forming an electrically conductive lower barrier layer that lines at least an upper portion of a sidewall of the contact hole;
• forming an electrically conductive contact plug that extends in the contact hole, is electrically coupled to the lower barrier layer and protrudes above a major upper surface of the electrically insulating layer;
• forming an electrically conductive upper barrier layer that extends on a protruded upper surface of the contact plug and on a surface of the lower barrier layer;
• and
• patterning 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.