DIELECTRIC-PROPERTIES OF UNANNEALED ECR-SPUTTERED (BA,SR)TIO3 FILMS UNDER DC-BIAS STRESSES

Changes in leakage current and polarization hysteresis loops of (Ba0.5 5Sr0.45TiO3 (BST) films for capacitor applications are found after +3 V and -3 V dc-bias stress tests. An electron cyclotron resonance sputt ering is used for depositing those 100-nm-thick films in Pt/BST/Pt str uctures. Comparison of characteristics with Pt/BST/Ti (2 nm)/Pt(bottom ) structures suggests that barrier degradation due to oxygen deficienc ies may occur near the interface of not only bottom electrodes but als o top electrodes. Electron traps also seem to be generated in BST film s. Polarization hysteresis data indicate that there is no clear ferroe lectric hysteresis and that the shape of the loops is probably control led by leakage current and charge trapping.