A device, which may include a semiconductor device, may include a contact plug, a first barrier metal covering a bottom surface of the contact plug and a lower sidewall of the contact plug, such that the first barrier metal exposes an upper sidewall of the contact plug, and an insulation pattern covering the upper sidewall of the contact plug such that the insulation pattern isolates the first barrier metal from exposure. A magnetic tunnel junction pattern may cover a top surface of the contact plug. Each element of the contact plug, the first barrier metal, and the insulation pattern may be in a contact hole of a first interlayer dielectric layer.