Methods of forming a phase change memory device

A method of forming a phase change memory device, comprising:

• injecting first to third source gases into a process chamber of a semiconductor deposition apparatus, wherein the first to third source gases are simultaneously injected into the process chamber while a semiconductor deposition process is performed, the first source gas comprises a germanium (Ge) precursor, the second source gas comprises an antimony (Sb) precursor, and the third source gas comprises a tellurium (Te) precursor;
• injecting a reaction gas into the process chamber during the injection of the first to third source gases, wherein an injection time and a pause time of the reaction gas are performed repeatedly and periodically during the injection of the first to third source gases;
• injecting a purge gas into the process chamber during the injection of the first to third source gases;
• and
• forming a phase change material layer on a interlayer insulating layer of a semiconductor substrate disposed in the semiconductor deposition apparatus using the first to third source gases, the reaction gas and the purge gas, wherein the interlayer insulating layer has an opening and the phase change material layer partially fills the opening.