AVS 52nd International Symposium
    Thin Films Monday Sessions
       Session TF-MoP

Paper TF-MoP44
Characterization of Barium Zirconium Titanate Thin Films as Tunable Materials Prepared by rf Magnetron Sputtering

Monday, October 31, 2005, 5:00 pm, Room Exhibit Hall C&D

Session: Aspects of Thin Films Poster Session
Presenter: W.-A. Lan, National Tsing Hua University, Taiwan, R.O.C.
Authors: W.-A. Lan, National Tsing Hua University, Taiwan, R.O.C.
T.-B. Wu, National Tsing Hua University, Taiwan, R.O.C.
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There are a large number of perovskite structure ABO@sub 3@ ceramics with nonlinear dielectric properties being studied. For Ba(Zr@sub x@T@sub 1-x@)O@sub 3@ (BZT), with increasing the Zr content, the dielectric constant decreases and the leakage current is reduced by suppressing the formation of Ti@super 3+@ and hopping conduction. The Zr@super 4+@ ion is chemically more stable than the Ti@super 4+@ and has a larger ionic size to expand the perovskite lattice and shifts the ferroelectric-to-paraelectric phase transition temperature toward room temperature. In this work, the sputtered BZT ferroelectric thin films with different Zr substitution under several deposition conditions were investigated. The BZT thin films were deposited by rf sputtering using a 2 inch target. The test structure was made in M-I-M structure. The bottom electrode is (001)-textured LaNiO@sub 3@ (LNO) conductive oxide which was deposited on the Pt/Ti/SiO@sub 2@/Si substrate by rf sputtering with a thickness of 200nm. The Ba@sub x@(Zr@sub y@Ti@sub 1-y@)O@sub 3@ targets were prepared by solid state mixing method using single phase calcined powders x of BaZrO@sub 3@ and (1-x) Ba@sub 2@TiO@sub 4@. The mixing ratio , x, were 0.15, 0.2, 0.25. The sputtering was conducted under different rf-sputtering power, substrate temperature, Ar/O@sub 2@ ratio and target stoichiometry. The deposition time was controlled at 1 hour to study the effects of sputtering conditions. Platinum top electrode of 75 nm thick was deposited by rf sputtering at room temperature. Lift-off process was used to defined the pattern in circles with different radius. The crystalline phases of the films were examined with x-ray diffraction. Cross-sectional morphologies and thickness of the films were examined by field emission SEM. The dielectric properties of the films were measured with 4192A from 1 kHz to 1MHz. The voltage dependence of dielectric constant and loss tangent was measured with 4284A at 1 MHz.