Variations of magnetic properties for various nitrogen concentration in Ta thin films for spin valve structure

In this report, we investigate the change of magnetic property in spin valve devices for various nitrogen concentrations of Ta underlayer. Spin valve samples were deposited on, SiO₂ substrate by using DC magnetron sputtering system with 2 inch 8 targets. The substrates were-P doped (100) Si wafers with resistivities of 5-6 Ω-cm 2000 Å-thick; thermal oxide was deposited for prohibiting the shunting current effect and the spin valve samples with sample size of 1 inch × 1 inch were deposited with linewidth of 200 μm and 500 μm, respectively. The spin valve structure is Si/SiO₂/Ta(Ta-N)/NiFe/CoFe/Cu/CoFe/FeMn/Ta. Base pressure was less than 2.0 × 10^-7 Torr and TaN thin film were deposited with various N₂ gas flow between 0 and 12 sccm. To obtain the magnetic anisotropy, we apply 600 Oe magnetic field for substrate surrounding. The XRD pattern of the Ta thin film with various gas flow was taken, as well as the resistivity and rms roughness as functions of gas flow ratios.