Structural and ferroelectric properties of r.f. magnetron sputtered SrBi/sub 2/Ta/sub 2/O/sub 9/ thin films

Abstract

Radio-frequency magnetron sputtering was used to deposit SrBi/sub 2/Ta/sub 2/O/sub 9/ ferroelectric thin films on Pt(111)/Ti/SiO/sub 2//Si(100) substrates with 15% Bi/sub 2/O/sub 3/ excess SrBi/sub 2/Ta/sub 2/O/sub 9/ ceramic target. Thin films were deposited at room temperature with argon pressures of 0.5/spl sim/100 mTorr and sputtering power of 200 W. Deposited thin films were post-annealed at 800/spl deg/C for 2 hours in O/sub 2/ atmosphere. Structural properties were investigated with X-ray diffraction techniques. And microstructures were observed by the scanning electron microscope. Crystal orientations and microstructures of the thin films were strongly affected by the argon pressures during the deposition. Ferroelectric properties of the Pt/SrBi/sub 2/Ta/sub 2/O/sub 9//Pt capacitors were obtained. The physical properties of the c-axis oriented and polycrystalline SrBi/sub 2/Ta/sub 2/O/sub 9/ were compared. The c-axis oriented thin films show good ferroelectric properties, (P*/sub r/-P/sup /spl circ///sub r/) and E/sub c/ were 10.4 /spl mu/C/cm/sup 2/ and 50 kV/cm, respectively. And for the polycrystalline thin film, (P*/sub r/-P/sup /spl circ///sub r/) and E/sub c/ were 6.5 /spl mu/C/cm/sup 2/ and 43 kV/cm, respectively.