1. An integrated circuit device, comprising: a semiconductor substrate having a surface region; a gate dielectric layer overlying the surface region of the substrate; an MOS device formed on the semiconductor substrate, the MOS device comprising a gate structure overlying the gate dielectric layer, a first active region, and a second active region; a first conductor structure overlying the first active region to electrically coupled the first conductor structure to the first active region of the MOS device; a second conductor structure overlying the second active region; and a resistive switching device coupled to the MOS device, the resistive switching device comprising a first electrode, a second electrode, and a switching region, the first electrode overlying the first conductor structure, the switching region comprising an amorphous silicon material overlying the first electrode, and the second electrode comprising at least a conductive material overlying the switching region to cause the conductive material to be in contact with the switching region.