溶胶—凝胶法制备锆掺杂二氧化铪基纳米薄膜的工艺及性能研究

发布时间：2018-03-15 06:05

  本文选题：二氧化锆　切入点：二氧化铪　出处：《大连理工大学》2015年硕士论文　论文类型：学位论文

【摘要】：以HfO：和ZrO2为基的二元氧化物材料因具有高介电常数(High-k),在微电子领域早已成为研究热点并被实际大规模应用,已广泛取代SiO2作为金属氧化物半导体(CMOS)晶体管栅介质和动态随机存储器(DRAM)电容器介质。近几年的研究发现,使用特殊工艺制备的HfO2基薄膜具有优异的铁电性质。若采用该类铁电材料取代Pb(Zr,Ti)O3 (PZT)、SrBi2Ta2O9(SBT)和(Bi1-xLax)4Ti3O12 (BLT)等传统的钙钛矿结构基铁电材料来制备铁电半导体器件如铁电非易失性存储器,预计在存储密度和性能方面或将有重大突破。本论文以纳米薄膜材料的相变理论为指导,采用对设备条件要求不高、操作简单的纯水基溶胶-凝胶法制备HfxZr1-xO2(x=0、0.5、1)薄膜。实验中,对纯水基溶胶-凝胶法制备工艺进行了探索和优化,利用热重/差热同步分析仪分析溶胶的热性能；利用甩胶法制备薄膜；利用原子力显微镜(AFM)以及扫描电镜(SEM)测定薄膜的表面形貌：利用X射线反射(XRR)法对薄膜厚度、密度及表面粗糙度进行分析；利用掠入射X射线衍射(GIXRD)法对薄膜物相进行分析；利用X射线光电子能谱(xPS)分析薄膜各元素含量和化学键结合情况；利用铁电性能测试分析仪对薄膜电容器的极化曲线、漏电流密度等电性能进行测试。实验结果表明,纯水基溶胶-凝胶法可实现对薄膜厚度的精确控制。表面AFM形貌图显示薄膜表面光滑、平整且无明显的气孔和微裂纹。XPS结果显示薄膜各元素含量比符合化学计量比。GIXRD结果显示60.0nm的Zr02薄膜在550℃-600℃发生晶化,室温下呈四方相,60.0nm厚的Hf02薄膜在600℃-700℃发生晶化,室温下呈单斜相。由于表面能效应,薄膜厚度与相组成密切相关,随着薄膜厚度的增加,Hf0.5Zr0.5O2薄膜在室温下的结晶相由四方相逐渐向单斜相转变。ZrO2的添加有助于Hf02四方相的稳定,在12.9nm以下,Hf0.5Zr0.5O2薄膜在室温下完全结晶为四方相。相组成与薄膜介电常数密切相关,反映到P-E测量曲线中,14.7nm HfO2、12.9nm Hf0.5Zr0.5O2和29.5nm ZrO2薄膜室温下的结晶相为单斜相向四方相转变,对应于介电常数依次增大,分别为13.6、27.8和42.1,薄膜漏电流密度在场强为1MV/cm下分别为2.4×10-6、3.5×10-6和2.2×10-6A/cm2。
[Abstract]:Due to their high dielectric constant, the binary oxide materials based on HFO: and ZrO2 have become a hot spot in the field of microelectronics and have been widely used in many fields. SiO2 has been widely replaced as gate dielectric of metal oxide semiconductor (MOSFET) transistor and capacitor dielectric of dynamic random access memory (DRAM). HfO2 based thin films prepared by special process have excellent ferroelectric properties. Traditional perovskite-based ferroelectric materials such as PbBZZrTiO3 / PZTO _ 3, SrBi2Ta2O9SBTand Bi1-xLaxTi3O12) are used to fabricate ferroelectric semiconductor devices such as ferroelectric nonvolatile memory. It is expected that there will be a great breakthrough in storage density and performance. HfxZr1-xO2O2HfxZr1-xO2OXO00.51) thin films are prepared by pure water-based sol-gel method, which is guided by phase transition theory of nanocrystalline thin films. The preparation process of pure water based sol-gel method was explored and optimized. The thermal properties of sols were analyzed by thermogravimetric / differential thermal synchronous analyzer (TG-DTA), and the films were prepared by gelation method. Atomic force microscopy (AFM) and scanning electron microscopy (SEM) were used to determine the surface morphology of the films. The thickness, density and surface roughness of the films were analyzed by X-ray reflectance (XRR) method, and the phase of the films was analyzed by grazing incident X-ray diffraction (GIXRD) method. X-ray photoelectron spectroscopy (XPS) was used to analyze the element content and chemical bond binding of the film, and the polarization curve, leakage current density and other electrical properties of the thin film capacitor were measured by ferroelectric property analyzer. The pure water based sol-gel method can accurately control the film thickness. The surface AFM topography shows that the film surface is smooth. The results of flat and no obvious porosity and microcrack. XPS showed that the content ratio of each element in the film was in accordance with stoichiometric ratio. The results showed that 60.0nm Zr02 film crystallized at 550 鈩，

本文编号：1614732