Surface plasmon resonance analysis of insulating AlO/sub x/ barrier in magnetic tunnel junctions prepared by natural oxidation method

The AlO/sub x/ insulating barrier in MTJ was fabricated and analyzed by utilizing a natural oxidation and surface plasmon resonance spectroscope (SPRS) technique. The basic structure of MTJ was Ta/CoFe/AlO/sub x/:natural oxidation/NiFe/Ta. SPRS was used to investigate optimum thickness and dielectric properties of the AlO/sub x/ layers. The SPRS results exhibited changes in the oxidation state of the barrier, depending on the oxidation time. Natural oxidation depth and speed were calculated by comparing SPRS simulation results with experimental ones. It was also found that 8 /spl Aring/ of Al layer is the optimum thickness when MTJ was formed using natural oxidation method.