A semiconductor structure includes a resistance variable memory structure. The semiconductor structure also includes a dielectric layer. The resistance variable memory structure is over the dielectric layer. The resistance variable memory structure includes a first electrode disposed over the dielectric layer. The first electrode has a sidewall surface. A resistance variable layer has a first portion which is disposed over the sidewall surface of the first electrode and a second portion which extends from the first portion away from the first electrode. A second electrode is over the resistance variable layer.