本文選題：PHT　切入點：鐵電　出處：《電子科技大學》2015年碩士論文　論文類型：學位論文

【摘要】：鐵電薄膜材料是具有介電、壓電、熱釋電、鐵電等性質的功能材料,被廣泛應用于集成電子學、微電子學、微機電系統(tǒng)、光電子學等重要領域。鐵電薄膜是非易失性隨機存儲器(NVRAM)的重要組成部分。隨著現(xiàn)代科學技術和信息處理技術的高速發(fā)展,對NVRAM是的存儲密度、穩(wěn)定性及使用壽命都有了越來越高的要求。雖然傳統(tǒng)的鐵電材料(PZT、SBT等)的制備技術已很完善,但其在工業(yè)應用方面還存在一些問題,如鐵電疲勞、制備溫度高等。探索可用于NVRAM的新型高性能鐵電材料越來越重要。鈣鈦礦結構Pb(HfxTi1-x)O3(PHT)鐵電薄膜具剩余極化強度高、矯頑場低、介電常數(shù)大、成分可調、抗疲勞特性好等優(yōu)點,可作為NVRAM的候選鐵電材料。本論文以鈣鈦礦結構的鐵電薄膜PHT為研究對象,對PHT與半導體材料(Si、GaN)的集成結構進行了系統(tǒng)的研究。主要開展了以下工作:探索Pt(111)/TiO2/SiO2/Si襯底上PHT薄膜的最優(yōu)生長工藝;在Al2O3襯底上研究緩沖層對PHT薄膜微觀結構及性能的影響,并研究不同底電極對PHT薄膜的影響;初步探索鐵電薄膜PHT與半導體GaN集成結構的性能。1、首先在Pt/TiO2/SiO2/Si襯底上采用PLD法制備PHT薄膜,探索PHT的最優(yōu)制備工藝。制備鐵電電容結構(MIM),研究PHT薄膜的本征電學性能。研究發(fā)現(xiàn),生長過程中氧分壓和生長溫度對PHT薄膜的擇優(yōu)取向、鐵電極化及漏電流都有顯著的影響。然后引入低溫自緩沖層技術,有效改善薄膜的微觀結構和電學性能。此外,本論文還對比了不同生長溫度的自緩沖層對PHT薄膜的微觀結構及電學性能的影響,發(fā)現(xiàn)插入300℃自緩沖層得到沿(111)取向的高質量外延PHT薄膜,薄膜晶粒大小均勻,且表面平整、結構致密。與600℃直接沉積的PHT薄膜相比,300℃自緩沖層下外延薄膜的漏電流密度降低了3-4個數(shù)量級,剩余極化強度提高到63μC/cm2,矯頑場強降低至190 kV/cm,抗疲勞特性也得到了顯著改善。2、對比研究了Al2O3襯底上直接和用MgO緩沖沉積PHT薄膜的微觀結構,發(fā)現(xiàn)插入MgO緩沖層可使得PHT薄膜沿(111)擇優(yōu)取向生長,且薄膜結晶質量良好,表面平整致密。然后對比Pt和SRO底電極對Al2O3襯底上沉積的PHT薄膜的微結構與電學性能的影響,發(fā)現(xiàn)由于SRO與PHT都為鈣鈦礦結構且具有相似的晶格常數(shù),且SRO中的氧原子對PHT薄膜中的氧空位起到一定的補償作用,可以減少薄膜中的缺陷,SRO下電極上沉積的PHT薄膜具有更好的絕緣特性、更高的剩余極化強度、更強的抗疲勞特性。最后選用SRO為底電極,研究了MgO緩沖層對PHT薄膜電學性能的影響。3、對GaN襯底上制備的PHT薄膜進行了研究。發(fā)現(xiàn)在MgO緩沖作用下實現(xiàn)了PHT(111)薄膜在GaN襯底上的外延生長,且延續(xù)了MgO在GaN上生長的外延關系:PHT(111)//MgO(111)//GaN(0002);PHT[1-10]//MgO[1-10]//GaN[11-20]。分別制備Au/Ni/PHT/GaN(MFS)和Au/Ni/PHT/MgO/GaN(MFIS)結構并對其電學性能進行測試。
[Abstract]:Ferroelectric thin films are functional materials with dielectric, piezoelectric, pyroelectric and ferroelectric properties. They are widely used in integrated electronics, microelectronics, micro-electromechanical systems, etc. Ferroelectric thin film is an important component of nonvolatile random access memory (NVRAM). With the rapid development of modern science and technology and information processing technology, NVRAM is the storage density. Although the preparation technology of the traditional ferroelectric material PZT / SBT is very perfect, there are still some problems in its industrial application, such as ferroelectric fatigue. The preparation temperature is high. It is more and more important to explore new high performance ferroelectric materials that can be used in NVRAM. The perovskite structure PbHfxTi1-xO3PHTs have the advantages of high remanent polarization, low coercive field, large dielectric constant, adjustable composition and good fatigue resistance, etc. In this thesis, perovskite structure ferroelectric thin film PHT is used as the research object. In this paper, the integrated structure of PHT and semiconductor material (SiGN) is systematically studied. The main work is as follows: to explore the optimal growth process of PHT films on Pt(111)/TiO2/SiO2/Si substrates, to study the effect of buffer layer on the microstructure and properties of PHT films on Al2O3 substrates, and to study the effect of buffer layer on the microstructure and properties of PHT films. The effects of different bottom electrodes on PHT thin films were studied, and the properties of the integrated structure of ferroelectric film PHT and semiconductor GaN were investigated. Firstly, PHT thin films were prepared on Pt/TiO2/SiO2/Si substrates by PLD method. The optimum preparation process of PHT was explored. The ferroelectric capacitance structure was prepared and the intrinsic electrical properties of PHT thin films were studied. It was found that oxygen partial pressure and growth temperature had preferential orientation on PHT films during the growth process. Iron electrode and leakage current have significant effects. Then, the low temperature self-buffer layer technology is introduced to effectively improve the microstructure and electrical properties of the film. The effects of self-buffer layers at different growth temperatures on the microstructure and electrical properties of PHT thin films were also compared. It was found that the high quality epitaxial PHT thin films with high quality orientation were obtained by inserting the self-buffer layers at 300 鈩，

本文編號：1556400