Deposition Temperature Effect on Dielectric Properties of (Ba,Sr)TiO3 Thin Films for Microwave Tunable Devices

Author： Lee Bong Yeon Cheon Chae Il Yun Eui-Jung Kim Jeong Seog

ISSN： 1058-4587

Source： Integrated Ferroelectrics, Vol.49, Iss.1, 2002-01, pp. : 123-132

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Abstract

(Ba,Sr)TiO₃(BST) thin films were prepared on Pt/Ti/SiO₂/Si substrates by RF magnetron sputtering method using a multi-component oxide target at various temperatures, room temperature to 650□. As-deposited thin films were annealed at 650□ for 30 minutes under oxygen. Field-dependent dielectric properties were investigated as a function of the deposition temperature. C-V tunability and dielectric loss of the BST thin film were greatly dependent on the substrate temperature during deposition even after the films were post-annealed at 650□. Dielectric constant, tunability and dielectric loss increased with increasing deposition temperature. More stoichiometric (Ba+Sr)/Ti ratio is a major factor for large dielectric constant and tunability in the BST thin film deposited at high temperature. Dielectric loss increased greatly at the deposition temperature above 600□ because of rough interface between the BST thin film and bottom electrode. Top-electrode annealing at 600□ reduced dielectric loss significantly. The BST thin film deposited at 600□ showed the best field-dependent dielectric properties, tunability of 57%, dielectric constant of 368 and dielectric loss of 0.026 at 10 kHz.