Characterization and modeling of tunnel barrier reliability

Summary form only given. The reliability of ultra-thin dielectric film composing the ferromagnetic tunnel junctions (MTJs) is of great importance for MRAM development. Considerable work has been done in the area of gate oxide, however there are relatively few works in ultra-thin aluminum oxide serving as a tunnel barrier. In this work, the dielectric breakdown of MTJs is investigated, by means of current sweep experiments and time-to-breakdown measurements on a series of patterned MTJs with both different junction area and stress conditions. We will present the analytical results and discussions of the breakdown mechanism of MTJs. The MTJs used in this work were dual spin valve-type double tunnel junctions prepared by the ultra-high vacuum sputtering technique, having the structure SiO/sub 2//Ta/NiFe/IrMn/Co/sub 50/Fe/sub 50/(2 nm)/AlO/sub x//CoFeNi(3 nm)/AlO/sub x//Co/sub 50/Fe/sub 50/(2 nm)/IrMn. The tunnel barriers were fabricated by deposition of 0.8 nm Al following in-situ plasma oxidization. The samples were patterned using photolithography and ion milling.