Provided are semiconductor devices and methods of fabricating the same. In methods of forming the same, an etch stop pattern and a separate spacer can be formed on a sidewall of a bit line contact, wherein the etch stop pattern and the separate spacer each comprise material having an etch selectivity relative to an oxide. A storage node contact plug hole can be formed so that the etch stop pattern and the separate spacer form a portion of a sidewall of the storage node contact plug hole spaced apart from the bit line contact. The storage node contact plug hole can be cleaned to remove a natural oxide formed in the storage node contact plug hole. Related devices are also disclosed.