Effects of sputtering angle on surface roughness, chemical composition, and GMR behavior of NiO & /spl alpha/-Fe/sub 2/O/sub 3/ bottom spin-valves

Summary form only given. The effects of sputtering angle on interfacial surface roughness, chemical composition, and giant magnetoresistance (GMR) behaviors have been investigated by using anti-ferromagnetic NiO and /spl alpha/-Fe/sub 2/O/sub 3/ bottom spin-valves. To study effects of sputtering angle, 50 nm thick NiO and /spl alpha/-Fe/sub 2/O/sub 3/ films were deposited by RF reactive sputtering of 8" diameter Ni and Fe targets at different radial positions on 4" diameter Si(100) wafers to vary average sputtering angle. Multilayers of Co(3)/Cu(2.5)/Co(3 nm) were subsequently deposited. The authors show a dramatic decrease of surface roughness from Ra=0.758 nm at center of wafer to Ra=0.368 nm at edge and corresponding increase of GMR ratio from 13.5-19.8% for NiO and 9.8-13% for /spl alpha/-Fe/sub 2/O/sub 3/. According to cross-section transmission electron microscopy (XTEM), atomic force microscopy (AFM), and x-ray photoelectron spectroscopy (XPS) analyses of NiO bottom GMR spin-valves, the higher GMR ratios were found to result from smoother surfaces and higher-oriented crystalline textures, and nearly bulk stoichiometries. With increasing off-axis sputtering angle from the center of the target, the deposited anti-ferromagnetic oxide films were found to have higher densities, lower defects, and much smoother surfaces. There significant observed effects are thought to be due to smaller channeling effects and reduction of re-sputtered of atoms from the substrate surface are caused by the lower kinetic energy of the sputtered atoms.