after forming a capacitor of a stack type ferroelectric memory device by sequentially patterning an upper electrode , a ferroelectric film and a lower electrode formed above an interlayer insulator film , the capacitor is covered with an oxidation barrier layer . after forming the oxidation barrier layer , the in - process memory device is heat treated at a high temperature in an oxygen - containing atmosphere . the oxidation barrier layer prevents the lower electrode of the capacitor and a barrier metal film between the capacitor and the interlayer insulator film from oxidation during heat treatment . thus , the occurrence of peelings and hillocks in the lower electrode and the barrier metal film is avoided so that a semiconductor memory has good electrical characteristics and high reliability .