1. A variable resistance memory device comprising: a first electrode and a second electrode; a chalcogenide glass layer between the first electrode and the second electrode, the chalcogenide glass layer including a chalcogenide glass material co-deposited with a metal material; a metal ion source structure between the chalcogenide glass layer and the second electrode; and a buffer layer between the first electrode and the chalcogenide glass layer, wherein the buffer layer includes the chalcogenide glass material and excludes the metal material.