C-Axis Oriented Ba-Ferrite Thin Film With Perpendicular Anisotropy Deposited on Si<tex>$_3$</tex>N<tex>$_4$</tex>Substrate

Abstract

Si/sub 3/N/sub 4/, a new substrate as well as thermally oxidized SiO/sub 2//Si wafer substrate were used to prepare hexagonal Barium ferrite (BaM) thin films by facing target sputtering system. At substrate temperature (Ts) of 600/spl deg/C, the intensities of BaM [00l] planes in X-ray diffraction diagrams were much stronger in the case of Si/sub 3/N/sub 4/ substrate than that of SiO/sub 2//Si wafer substrate. The value of /spl Delta//spl theta//sub 50/ was found about 2.28/spl deg/ for 25-nm thickness of BaM deposited on Si/sub 3/N/sub 4/. Then, Ts was reduced to 525/spl deg/C. Perpendicular coercivity (Hc/sub perp/) and squareness ratio (S/sub perp/) were higher in the case of Si/sub 3/N/sub 4/ substrate even at 525/spl deg/C. The maximum value of Hc/sub perp/=3.25 kOe and S/sub perp/=0.7 was found for the film of 35 nm. It was found that Si/sub 3/N/sub 4/ not only reduces the Ts of BaM during in-situ deposition but also increases the perpendicular anisotropy of BaM thin film.