An example embodiment relates to a method including forming a bottom electrode and an insulating layer on a substrate, the insulating layer defining a first opening that exposes a portion of the bottom electrode. The method includes forming a variable resistance material pattern, including a plurality of elements, to fill the first opening. The variable resistance material pattern may be doped with a dopant that includes at least one of the plurality of elements in the variable resistance material pattern. The method includes forming a top electrode on the variable resistance material pattern.