Effects of pumping time on GMR and coercivity of RF-sputtered MRAM dual spin-valves

The effects of residual oxygen in a deposition vacuum chamber on the GMR performance of RF-sputtered MRAM dual spin-valves have been studied by varying the pumping time while maintaining a constant base pressure of 5/spl times/10/sup -7/ Torr. By increasing only the pumping time from 1.5 to 8 hours, the GMR ratio of Si/NiFe/Cu/Co/Cu/NiFe dual spin-valves increased from 1.2 to 2.9%, and coercivity of NiFe decreased from 11 to 5 Oe and coercivity of Co decreased from 80 to 15 Oe. According to depth profiles of the chemical composition using AES and XPS, the oxygen content decreased substantially with increasing pumping time. This result implies that the partial oxidation inside or at the interfaces of multilayers is a "GMR killer" which causes incomplete anti-parallel spin alignment of the dual spin valves.