【作者】 袁媛；

【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】 BST由于其良好的铁电、介电、热释电性及绿色环保性,被广泛的应用于动态随机存储器DRAM、红外传感器UFPA、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的制备技术,对于铁电器件的发展具有重要的理论意义和实用价值。本课题针对DRAM、UFPA和FeRAM器件应用的典型膜厚需求,在化学修饰的溶胶-凝胶工艺的基础上,引入PVP改性剂,采用直接感光法单次制备得到了介电性能良好的BST图形化薄膜。研究发现:(1)采用乙酸钡、乙酸锶、钛酸丁酯为出发原料,以醋酸与甲醇为溶剂,以乙酰丙酮为化学修饰剂,以PVP为开裂抑制剂,能够合成制备具有紫外感光特性的BST溶胶,溶胶浓度约为0.7-0.8mol/L,紫外敏感波长约为325nm,单次制备的BST图形化薄膜:其介电常数约为600,介电损耗约为0.03;(2)PVP的引入提高了单次制备的BST薄膜厚度,抑制了薄膜开裂,随PVP的添加量不同,单次制备的BST薄膜厚度从200～800nm范围可调,当PVP的添加量与溶剂的质量比达到1:30以上时,可明显抑制BST薄膜的开裂;(3)采用200℃烘干20min→500℃预处理20min→700℃热处理30min→随炉冷却的阶段热处理工艺,有利于发挥PVP添加剂的开裂抑制效果,可以单次制备得到致密的BST钙钛矿相图形化薄膜,厚度可以达到800nm左右。结果表明:采用直接感光法单次制备BST图形化薄膜的方法是可行的。更多还原

【Abstract】 BST films are widely used in the dynamic random access memory,uncooled focal plane array,non-volatile ferroelectric random access memories and many other fields for their great performance in ferroelectricity,dielectricity,pyroelectricity and environmental protection.For the application in ferroelectric integrated device,the BST film needs a certain thickness and specific film pattern.Therefore,the process of BST film fine patterning with specific thickness has great significance.Aiming at the thickness and patterning requirement of DRAM,UFPA,FeRAM application, base on chemical modified Sol-gel process with PVP as additive agent,the patterned BST films with good dielectricity were obtained by direct-patterning and single-dip-coating process.The conclusions are drawn as follows:(1)Using Barium acetate,strontium acetate and tetrabutyl titanate as starting materials,acetic acid and methanol as solvent,acetylacetone as chemical modifier,PVP as additive agent,photosensitive BST sol with concentration of about 0.7-0.8M were synthesized,its sensitive wavelength is about 325nm.The patterned BST films can also prepared by direct-patterning and single-dip-coating process,the dielectric constant and dielectric loss of which are about 600 and 0.03,respectively.(2)Additive PVP can increase the thickness of BST film and suppress cracking tendency,the thickness of BST films can be prepared from 200 to 800nm by adjusting the additive amount of PVP,and the PVP can suppress cracking-tendency at the addition mass ratio PVP and solvent above 1:30.(5;)The stage-by-stage heat treatment process of 200℃→500℃→700℃can exert the suppressing-crack role of PVP.The dense BST patterned films with perovskite structure and thickness of about 800rim were prepared by the method.The results indicate that the direct patterning and single-dip-coating process for BST film patterning is feasible.更多还原