Provided is a method of forming a phase change memory device, the method including washing and rinsing a phase change device structure. A phase change material layer may be formed on a semiconductor substrate. The phase change material layer may be etched so as to form a phase change device structure. The semiconductor substrate on which the phase change device structure is formed may be washed using a washing solution including a reducing agent containing fluorine (F), a pH controller, a dissolution agent and water. In addition, the semiconductor substrate on which the washing is performed may be rinsed.