多层模型计算椭偏法测量的SiO2／Si超薄膜厚度

采用不同的光学模型对厚度为6nm,密度为2．2g/cm2。的理想Si02薄膜理论曲线进行了拟合,得到了薄膜厚度的计算结果随所采取的薄膜密度变化的规律：选用更大的薄膜密度值进行拟合计算会得到更小的厚度结果,其趋势近似线性．参考GIXRR方法测量得到的薄膜物理结构的结果,给出了优化的拟合计算模型（薄膜密度为2．4g／cm3、表面粗糙度为0．4nin、界面粗糙度为0．3nin）,对于热氧化法制备的厚度小于10nrn的SiO2超薄膜,使用此模型进行拟合计算,可以得到比常规模型更为准确的厚度结果．采用优化的模型拟合了期望厚度为2,4,6,8,10nrn的si02超薄膜的SE实验曲线,得到的厚度结果分别为2．61,4．07,6．02,7．41,9．43nm,与传统模型计算结果相比,分别降低了13．8％,10．3％,8．1％,7．3％和6．6％．     

X射线反射法分析ZnO基薄膜的厚度、密度和表面粗糙度

采用X射线反射法(XRR)测试了在SiO_2玻璃衬底上磁控溅射沉积的单层ZnO基薄膜的反射强度,得到了反射强度随掠入射角变化的曲线;讨论了薄膜厚度、密度和表面粗糙度与反射曲线的关系,最后通过拟合XRR曲线获得了所制备薄膜的厚度、密度和表面粗糙度分别为55.8 nm,5.5 g·cm~(-3)和1.7 nm,与利用XRR数据直接计算出的薄膜厚度56.2 nm仅相差0.4 nm,表面粗糙度也与AFM测试的结果基本相符。可见XRR能无损伤、精确且快速地测试薄膜试样的厚度、密度和表面粗糙度等参数。     

纳米尺度氧化铪薄膜膜厚标准物质的研制

研制了氧化铪(HfO2)层厚度名义值分别为1nm、5nm、10nm的3种氧化铪薄膜膜厚标准物质,采用溯源至SI长度和角度基准的纳米薄膜厚度校准装置为标准物质候选物定值.研究建立了具有普适性的四层拟合模型,基于该模型对不同厚度的氧化铪薄膜的测量曲线进行了拟合,这是拟合结果准确可靠的基础.氧化铪薄膜膜厚标准物质具有良好的均...     

LaAlO3/BaTiO3超晶格薄膜界面结构分析

通过研究发现,利用激光分子束外延技术生长的LaAlO3/BaTiO3超晶格薄膜具有良好的电学性能,其剩余极化可达到25μc/cm2.性能决定于结构,因此本文分析研究了LaAlO3/BaTiO3超晶格薄膜的界面结构.首先通过高能电子衍射技术在薄膜生长过程中对各层的生长及界面状况进行观测,再通过小角X射线衍射曲线及其计算机拟合曲线进一步确定超晶格薄膜的界面及结构参数,如界面的粗糙度、单层厚度等.通过研究发现,由于晶格之间的差异,LaAlO3/BaTiO3超晶格薄膜中LaAlO3和BaTiO3层的生长过程及微结构存在着一定的差异.     

溶剂蒸汽辅助制备超薄PVP栅介质膜及性能研究

使用溶剂蒸汽辅助制备超薄PVP栅介质膜,得到了低漏电流密度(E=1 MV/cm时,为1.12×10-9A/cm2;E=2 MV/cm时,为5.42×10-9A/cm2)、膜厚为10 nm的超薄PVP栅介质膜,其单位面积栅电容达到了566 nF/cm2。此外,AFM测试表明溶剂蒸汽辅助退火使薄膜表面粗糙度由0.36 nm降到了0.21 nm,空间电荷限制电流法(SCLC)的分析结果表明薄膜体内陷阱密度减少了26%。     

纳米ZrO2薄膜的制备与表征

用水热盐溶液水解法可合成含有单斜相晶态纳米ZrO2颗粒的ZrO2溶胶体.用匀胶法制备的纳米ZrO2薄膜厚度约160 nm,折光率为1.56.纳米ZrO2薄膜表面质量良好,无表面裂隙,台阶仪研究表明薄膜表面粗糙度算术差Ra=2.7 nm,均方根差Rq=3.7 nm.以ZrO2为高折射率膜层,碱催化的溶胶凝胶SiO2为低折射率膜层,制备了SiO2/ZrO2多层高反射率薄膜,10周期的SiO2/ZrO2多层膜系,在1.06 μm波段处透过率为1%,薄膜表面抗激光损伤阈值约15 J/cm2(1.06 μm,2.5 ns高功率激光作用下).     

表面波方法表征纳米多孔SiO2薄膜机械特性的对准技术

超声表面波方法表征薄膜材料机械特性的过程是将理论计算的色散曲线与实验所得的色散曲线进行拟合,获得所测薄膜样品的杨氏模量值．因此,实验信号的有效性是获得准确结果的最重要因素．双端压电传感探头的设计确保了实验测试条件与理论计算模型的一致性,从而进一步增加了测定结果的准确性．应用此技术对纳米多孔SiO2薄膜的机械性能进行了测定,当其膜密度为1．15g/cm^3时,拟合出的杨氏模量值为1．5GPa．分析结果还表明影响拟合结果准确性的实验因素主要是压头的位置与平头表面波的角度偏差．     

X射线反射法和椭圆偏振法结合测量热处理溶胶-凝胶ZrO2薄膜的结构和光学参数

采用溶胶-凝胶法在硅片基底上制备ZrO2薄膜,在150℃～750℃范围内不同温度下进行热处理,研究了热处理对膜层结构和光学性能的影响。X射线反射用于膜层厚度和界面粗糙度分析,结果表明热处理温度由150℃升至750℃,膜层厚度由常温状态下的112.3nm减小到34.0nm,表面和界面粗糙度均小于2nm。以X射线反射法测得的膜层厚度为初始值,对椭圆偏振仪的测量结果进行拟合,得到不同温度的膜层折射率,结果表明热处理温度为550℃时膜层折射率达到最大值。X射线反射作为直接的膜层厚度测试手段,所得结果为准确分析椭偏光谱提供了参考。     

纳米尺度HfO_2薄膜的光谱椭偏模型建立

为了建立厚度为1 nm左右HfO_2超薄膜的光谱椭偏测量方法,采用掠入射X射线反射技术进行国家/地区实验室间比对认证,其膜厚准确量值作为参比值,建立了HfO_2超薄膜的光谱椭偏结构拟合模型。研究了HfO_2超薄膜的光谱椭偏色散模型和拟合参数,最后确定了拟合色散模型为Tauc-Lorentz 3,拟合光谱范围为3.45~4.35 eV,表面污染层孔隙比例为60:40。     

疏水改性对SiO2气凝胶薄膜性能与结构的影响

以正硅酸乙酯(TEOS)为前驱体,采用溶胶-凝胶法制备SiO2气凝胶薄膜,并以不同体积分数的六甲基二硅胺烷(HMDZ)对SiO2气凝胶薄膜进行了疏水改性研究,采用椭偏仪、FITR、接触角测试仪、SEM和光谱仪等对薄膜的疏水性、微观结构及透光性进行了表征,研究了HMDZ疏水改性对SiO2气凝胶薄膜性能与结构的影响。结果表明,疏水改性后,SiO2胶粒表面的大部分亲水性-OH被疏水基团-CH3所取代,其与水的接触角达159°,疏水性好;SiO2气凝胶薄膜在可见光范围内透光率接近90%,透光性高;其孔隙率为78.8%,密度为0.464g/cm3,骨架颗粒尺寸小于40nm,具有纳米多孔网络结构特性。     

Controlling the crystallinity and roughness of atomic layer deposited titanium dioxide films

The surface roughness of thin films is an important parameter related to the sticking behaviour of surfaces in the manufacturing of microelectomechanical systems (MEMS). In this work, TiO2 films made by atomic layer deposition (ALD) with the TiCl4-H2O process were characterized for their growth, roughness and crystallinity as function of deposition temperature (110-300 degrees C), film thickness (up to approximately 100 nm) and substrate (thermal SiO2, RCA-cleaned Si, Al2O3). TiO2 films got rougher with increasing film thickness and to some extent with increasing deposition temperature. The substrate drastically influenced the crystallization behaviour of the film: for films of about 20 nm thickness, on thermal SiO2 and RCA-cleaned Si, anatase TiO2 crystal diameter was about 40 nm, while on Al2O3 surface the diameter was about a micrometer. The roughness could be controlled from 0.2 nm up to several nanometers, which makes the TiO2 films candidates for adhesion engineering in MEMS.     

Characterization of vapor-deposited l-leucine nanofilm

X-ray reflective measurements (XRR), atomic force microscopy and single wavelength ellipsometry were used to investigate the optical properties of thin l-leucine films deposited onto silicon substrates. The ellipsometry data (Ψ,Δ) were fitted with a four-layer-model, and the optical refractive index of the l-leucine film measured with ellipsometry was determined to be 1.37. With the conventional effective medium approximation theory and the ellipsometry results, the density of the l-leucine nanofilm was determined to be 70% (0.81 g/cm³) of crystalline l-leucine. This value was in good agreement with the density of 69% (0.80 g/cm³) obtained with XRR measurement. The ellipsometry measurements also enabled us to estimate the surface roughness or absorption layer of the film. This procedure of combined XRR and ellipsometry measurements could be a powerful tool for the determination of the (otherwise hard-to-determine) refractive index in thin organic material films with a rough surface layer.     

Spectrographic ellipsometry study of a liquid crystal display substrate consisting of thin films of SiO2, polyimide and indium tin oxide on glass

Variable angle spectrometric ellipsometry at room temperature is used to determine thin film parameters of substrates used in liquid crystal displays. These substrates consist of sequential thin films of polyimide (PI), on indium tin oxide (ITO),on SiO₂ deposited on a glass backing approximately 1.1 mm thick. These films were studied by sequentially examining more complex systems of films (SiO₂, SiO₂-ITO, SiO₂-ITO-PI). The SiO₂ layer appears to be optically uniform and flat. The ITO film is difficult to characterize. When this surface film's lower surface is SiO₂ and upper surface is an air-ITO-interface it is found that including surface roughness and variation of the optical properties with ITO thickness in the model improved the fit; suggesting that both phenomena exist in the ITO films. However, the surface roughness and graded nature of optical properties could be not determinable by ellipsometry when the ITO is coated with a polyimide film. The PI films are ellipsometrically flat and over the wavelength range from 500 to 1400 nm the real refractive index of polyimide films varying in thickness between 25 and 80 nm is well modeled by a two-term Cauchy model with no absorption. The ellipsometric thickness of the ITO layer is the same as the profilometric thickness; however, the ellipsometric thickness of the polyimide layers is roughly 10 nm larger than that obtained from the profilometer. These final observations are consistent with the literature.     

The effect of rapid thermal annealing on structural and electrical properties of TiB2 thin films

This work reports on the effect of post-deposition rapid thermal annealing on the structural and electrical properties of deposited TiB₂ thin films. The TiB₂ thin films, thicknesses from 9 to 450 nm, were deposited by e-beam evaporation on high resistivity and thermally oxidized silicon wafers. The resistivity of as-deposited films varied from 1820 μΩ cm for the thinnest film to 267 μΩ cm for thicknesses greater than 100 nm. In the thickness range from 100 to 450 nm, the resistivity of TiB₂ films has a constant value of 267 μΩ cm.

A rapid thermal annealing (RTA) technique has been used to reduce the resistivity of deposited films. During vacuum annealing at 7 × 10⁻³ Pa, the film resistivity decreases from 267 μΩ cm at 200 °C to 16 μΩ cm at 1200 °C. Heating cycles during RTA were a sequence of 10 s. According to scanning tunneling microscopy analysis, the decrease in resistivity may be attributed to a grain growth through polycrystalline recrystallization, as well as to an increase in film density.

The grain size and mean surface roughness of annealed films increase with annealing temperature. At the same time, the conductivity of the annealed samples increases linearly with grain size. The obtained results show that RTA technique has a great potential for low resistivity TiB₂ formation.     

IZO/Al/GZO multilayer films to replace ITO films

Multilayer transparent conducting oxide (TCO) film structures have been designed and fabricated to achieve both high conductivity and high transmittance. In this article we report a buffering method and introduction of an aluminum (Al) interlayer to enhance the electrical conductivity of the IZO/Al/GZO/ZnO multilayer film on glass. Hall measurement results show that this multilayer film has a remarkable increase in mobility compared to those without using an Al interlayer. The surface morphology shows a decrease in surface roughness as the Al layer thickness increases. We have shown that the use of a thin Al interlayer enhances the electrical conductivity without sacrificing its optical transmittance much. By optimizing the thickness of the Al layer, the lowest resistivity of 2.2 × 10⁻⁴ Ω cm and an average transmittance higher than 75% in a range from 400 to 800 nm have been achieved. These properties are acceptable for future TCO applications.     

Ellipsometry of thin films of copper phthalocyanine

Ellipsometric measurements have provided qualitative information on the optical properties of CuPC films deposited on a thin gold layer substrate. Detailed interpretation was complicated by variations in the density of the deposited layers and the surface roughness of the substrate. Films less than 100 nm thick can be satisfactory represented by a single homogeneous isotropic layer. Thicker films appear to be equivalent to an isotropic inner layer and an anisotropic outer layer, where the latter results from bulk deposition of CuPC with the molecules in a predominant orientation to the surface. Reasonable agreement has been obtained between film thicknesses measured by weighing and by ellipsometry, assuming a single homogeneous anisotropic film for thickness in excess of 150 nm.     

Fabrication of High Performance Laminated Polarization Splitters Consisting of Thick a-Si:H /SiO(x):H Multilayers

We report fabrication techniques ofa-Si:H/SiO(x):H multilayers having ample thickness and flat layer boundaries for high performance laminated polarization splitters (LPS's). In the new fabrication process we used the following techniques to achieve low stress and high surface flatness: SiO(x):H film deposition by rf sputtering with a mixture of Ar/H(2), two-step deposition using rf bias sputtering, and elimination of surface roughness and defects by mechanical polishing. This process enabled deposition of a multilayer as thick as 265 mum while preserving layer boundaries as flat as 1 nm (rms). As a result, LPS's having low loss, a large aperture, and a long splitting distance were successfully obtained. The high optical performance is applicable to functional devices integrated into fibers or planar waveguides.     

ITO透明导电薄膜厚度与光电性能的关系

透明导电薄膜的厚度制约其光电性质。本研究利用磁控溅射技术制备了厚度变化范围为200-1500nm的ITO薄膜,探索了薄膜颜色、可见光透过率、面电阻与膜厚的关系。薄膜颜色随着膜厚的增加呈现有规律的变化,可见光透过率随薄膜厚度的增加而呈现振荡下降趋势,并出现了极大值(紫红色),振荡趋势可用多光束干涉解释;薄膜面电阻随膜厚的增加呈减小趋势,薄膜厚度为1387nm时,面电阻为1.3Ω/□,薄膜最小电阻率为1.8×10-4Ω.cm。文章给出了可以通过选择恰当的薄膜厚度,以尽可能满足透明导电薄膜面电阻、透过率两个相互矛盾的指标。