【作者】 石春梅；

【导师】 张卫华；

【作者基本信息】 西安理工大学 ， 材料科学与工程， 2008， 硕士

【摘要】 锆钛酸铅镧铁电薄膜（PLZT）由于具备许多优良的铁电、介电性能、压电效应和电光效应等物理性能,被广泛的应用于动态随机存储器DRAM、非挥发性存储器FeRAM等铁电集成领域。对于铁电集成器件的应用,不仅要求一定的膜厚,而且需要特定的图形,因此,适应特定铁电器件膜厚和图形需求的图形化薄膜制备技术,对于铁电器件的发展具有重要的理论意义和实用价值。本研究针对DRAM和FeRAM器件应用的典型膜厚需求（0.2μm～0.3μm）,在化学修饰的溶胶-凝胶工艺的基础上,引入PVP改性剂,采用直接感光法研究单次制备得到的铁电、介电性能良好的PLZT图形化薄膜。研究发现:（1）采用乙酸铅、硝酸镧、乙酰丙酮锆、钛酸丁酯为出发原料,以乙二醇独甲醚和冰乙酸为溶剂,苯甲酰丙酮为主要修饰剂,PVP为开裂抑制剂,可以合成具有紫外感光特性的PLZT溶胶;其溶胶浓度约为0.6～0.7M,紫外敏感波长约为332nm,且其单次制备的PLZT薄膜厚度可以达到260nm左右;（2）单次制备的PLZT图形化薄膜:其图形单元的剩余极化约为6.68μC/cm²、矫顽场强约为41kV/cm、介电常数约为356、介电损耗约为0.025、漏电流密度小于1.0×10^-1μA/cm²、在10⁸极化循环后,未见明显极化翻转疲劳现象;（3）PVP的引入提高了单次制备的PLZT薄膜的厚度、抑制了薄膜的开裂,随PVP的添加量在1∶80～1∶10之间变化,单次制备的PLZT薄膜的厚度从180～600nm范围可调,当PVP的添加量在与溶胶的质量比达到1∶40以上时可明显抑制薄膜开裂;（4）选用200℃烘干15min→400℃预处理30min→650℃热处理30min→随炉冷却的阶段热处理工艺,结合PVP的开裂抑制效果,可以单次制备致密的PLZT钙钛矿相薄膜,薄膜晶粒尺寸约20～40nm。结果表明:采用直接感光法单次制备PLZT图形化薄膜的方法是可行的。更多还原

【Abstract】 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.更多还原