【作者】 姚侠；

【导师】 赵高扬； 张卫华；

【作者基本信息】 西安理工大学 ， 材料物理与化学， 2004， 硕士

【摘要】 钛酸锶钡（BST）薄膜具有较高的介电常数和较低的介质损耗，在动态随机存储器（DRAM）、传感器、探测器等方面应用前景广阔。本文旨在采用Sol-Gel法，通过掺杂Sn元素改善BST薄膜的介电性能，并采用溶胶—凝胶与化学修饰相结合的新技术制得BST薄膜的微细图形。采用紫外—可见光光度仪、X射线衍射仪、LCR数字电桥等手段，分别探讨了光敏性溶胶的感光性、薄膜晶体结构及各种因素对薄膜介电性能的影响，结论如下： （1）用SrCl₂作为锶源，用Ti（OC₄H₉）₄、BaAc₂为出发原料， 乙二醇甲醚（MOE）为溶剂，按照Ti：AcAcH：MOE=1：2：30，BaAc₂：Kt：MOE=1：3：30，Sr：MOE=1：30的比例，配制出稳定，成膜良好的溶胶，溶胶长时间放置，性状无明显变化。 （2）首次在ITO／玻璃上制备了BST薄膜，其晶化温度为650℃。在自制的Pt／TiO₂／Si和低阻Si衬底上制备的BST薄膜，晶化温度为700℃。其中，在Pt／TiO₂／Si上制备的BST薄膜介电常数为388，与目前文献报道相当，相应的损耗为0.18。在低阻Si上制备的BST薄膜介电常数为342，介电损耗为0.05。 （3）以Sn²⁺为掺杂源，其最佳掺杂量为15％mol，在此掺杂量下，BST薄膜的介电常数为420，高于未掺杂薄膜，介电损耗为0.1。以Sn⁴⁺为掺杂源的BST薄膜，掺杂量为10％mol时，其介电常数和损耗分别为814和0.07，其介电常数高于掺杂同比例Sn²⁺的BST薄膜，也高于同类方法制备的BST薄膜。西安理工大学硕士学位论文 （4）以AcAcH为鳌合剂，添加比例为Ti4+:AcAcH二1:2，配制了光敏性溶胶。并用紫外光光照法制备了BST薄膜的微细图形，溶洗剂为乙醇，图形热处理后的厚度为约70nm。同样以BzAcH为鳌合剂，按Ti4+:BzAcH二1:0.8比例配制了光敏性溶胶。用此溶胶制备BST凝胶膜，通过激光干涉制备了BST薄膜光栅，溶洗剂为乙醇十去离子水，图形热处理后的厚度约为70nm，线宽约为0.5卜m。 （5）研究发现采用化学修饰法，引入鳌合剂BzAcH制备BsT溶胶，得到的BsT陶瓷薄膜具有更好的介电性能，在低阻Si上制备的BST薄膜，经700℃晶化IOmin，介电常数为550，损耗0.068，优于目前文献报道。更多还原

【Abstract】 Barium strontium titanate (BST) shows high dielectric constant and low dissipation factor and holds great promise for wide applications in dynamic random access memory (DRAM), transducer and infrared detector. In this paper, Sn-doped BST thin films with excellent dielectric property were prepared by Sol-Gel process. And the fine patterning of the films was fabricated by chemical modified method. The UV-Vis spectrometer was used to analyze the photosensitive property of the BST gel films. X-Ray diffraction meter and LCR numeral electric bridge were applied to study the crystal phase and the dielectric performance respectively. The results were shown as follows:(1) A stable BST precursor was prepared with SrCl2 Ti(OC4H9)4 and BaAc2 as starting materials, MOE as solvent, AcAcH as chelator. The molar ratio was Ti:AcAcH:MOE=1:2:30, BaAc2:Kt:MOE=l:3:30, Sr:MOE=l:30.(2) Fabricated BST thin films on ITO/glass substrate and the crystallization temperature of the film was 650℃. When the films on Pt/TiO2/Si and low resistance Si substrates was dwelled at 700℃ for 10min, the films were made up of perovskite totally. The permittivity of the film on Pt/TiO2/Si substrates were 388, whice was equal to that of reference, and the dissipation factor was 0.18. And the permittivity and dissipation factor on Si substrate were 342 and 0.05 respectively.(3) When the Sn2+ was used as dopant, 15mol% is the optimal additional amount. The BST films with 15mol% Sn2+ dielectric constant was 420, which was higer than that non-doped BST thin films. The dielectric constant of BST thin films with 10mol% Sn4+ was up to 814, such result is great higher than the BST films with 10mol% Sn2+and non-doped thin films, and the dissipation factor was 0.07.(4) A photosensitive sol can be prepared using AcAcH as chelator. And the optimal molar ratio was Ti4+:AcAcH=l :2. A fine-patterning can be fibricated by such percurtor with ethyl alcohol as solvent, and the thickness of the films was 70nm after annealing. The gel films derived from the BST sol with BzAcH as chelator, can be used to fabricate the fine pattern by laser interference method. The optimal molar ratio of BzAcH was Ti4+:BzAcH=l:0.8, and the solvent was ethyl alcohol and de-ionied water. After heat treatment, the thickness of the thin films was about 70nm and the line width was 0.5 urn.(5) When BzAcH was used as chelator to prepare BST precursor, BST thin films with better dieletric property can be fibracated. The permittivity and dissipation factor were 550 and 0.068 respectively. Such result was better than the reference refered.更多还原