A semiconductor device includes a first word line and a first bit line. The semiconductor device further includes a mold film disposed between the first word line and the first bit line, and a first memory cell disposed in the mold film. The first memory cell includes a first lower electrode in contact with the first word line. Side surfaces of the first lower electrode are in direct contact with the mold film. The first memory cell includes a first phase-change memory in contact with the first lower electrode, a first intermediate electrode in contact with the first phase-change memory, a first ovonic threshold switch (OTS) in contact with the first intermediate electrode, and a first upper electrode disposed between the first OTS and the first bit line, the first upper electrode in contact with the first OTS and the first bit line.