PLZT Patterned Films Prepared By Direct Patterning Process And Their Properties

PLZT films have many significant applications in the ferroelectric integrated fields such as ferroelectric random access memories (FeRAM), dynamic random access memories (DRAM), etc., because of their desirable physical properties such as ferroelectricity, dielectric properties, piezoelectricity and electric-optic effect. Certain thickness and pattern of ferroelectric film is needed in the application of ferroelectric integrated devices. Therefore, research on the film patterning with certain thickness and pattern used by ferroelectric apparatus have theoretical significance and practicable value for ferroelectric devices.In this paper, focusing on the PLZT film's application in DRAM, FeRAM, based on chemical modified Sol-gel process with PVP as additive agent, the patterned PLZT films with excellent dielectric and ferroelectric properties were prepared via single-step coating and direct-patterning process. The conclusions are draw as follows: (1) The PLZT photosensitivity sol can be prepared with acetylacetone (AcAcH), benzyl acetone (BzAcH)) as chemical modifier, lead acetate, lanthanum nitrate, zirconium(IV)2, 4-pentanedionate, titanium tetra-n butoxide as precursors, methoxyethane and acetic acid as solvent, and PVP as suppress-crack agent. The sol's concentration is about 0.6～0.7M, the UV-sensitive wavelength of which is about 332nm, the thickness of PLZT film prepared by single-step coating process is about 260nm. (2) The remnant polarization, coercive field and fatigue behavior of PLZT patterned film cell are about 6.68μC/cm², 41kV/cm and >10⁸ respectively, the dielectric loss and dielectric constant of PLZT patterned film cell are 0.025 and 356 at 10 kHz respectively, and leakage current is less than 10^-1μA/cm². (3) The additive of PVP can increase film thickness which prepared by single-step coating process, the relation between thickness and additive PVP mass is approximately linearity. PVP can suppress film crack significantly under the mass ratio of PVP:PLZT-Sol is more than 1:40. (4) The dense PLZT patterned film with perovskite structure are obtained after stage-by-stage heat-treatment (200℃, 15min→400℃, 30min→650℃30min→cooling in the furnace). The results indicate that the single-coating and direct-patterning process for the PLZT film patterning is feasible.