SiO2/Si膜厚标准样品校准相调制型光谱椭偏仪研究

椭圆偏振仪(或简称椭偏仪)在薄膜研究领域应用广泛.文章主要研究了相调制型光谱椭偏仪光路准直及参数优化过程,并通过硅上二氧化硅膜厚标准样品测量及数据拟合处理对光谱椭圆偏振仪进行校准.经过光路准直调整和参数优化后的椭圆偏振仪测量膜厚标准样品,拟合测量数据并将显示测量厚度值与标准样品厚度值比较,测量值在不确定范围内.     

一种光谱型椭偏仪的校准方法

针对光谱型椭偏仪校准结果受测量模型影响大的问题进行研究,提出一种不受测量模型影响的校准方法,即通过校准椭偏角实现光谱型椭偏仪的校准。依据椭偏仪测量原理,通过仿真分析确定实现较大范围内椭偏角校准所需标准样片的薄膜厚度量值,并采用半导体热氧化工艺制备出性能稳定的膜厚标准样片。使用标准样片对型号为M-2000XF的光谱型椭偏仪的椭偏角进行校准,样片厚度为2,50,500 nm对应的椭偏角偏差分别在±0.6°,±1.5°,±2°以内,该偏差对薄膜厚度的影响不超过±0.5 nm。经实验表明:该方法不受椭偏仪测量模型的影响,可有效解决光谱型椭偏仪的校准问题。     

用消光式椭圆偏振光谱测量薄膜光学参数的方法

本文主要介绍如何应用 TP—77型椭偏仪与 WDF 反射式单色仪组合,实现不同波长下的消光椭偏测量。此方法可测量薄膜厚度、折射率、吸收系数等光学参数。     

分振幅斯托克斯参量的椭偏测厚方法

为了实现对纳米级薄膜的快速测量,运用了基于分振幅斯托克斯参量测量的椭偏测厚的方法,对该方法中的原理.计算和参量测量方法进行研究,并构建了实验系统.首先,设计了一个光路在同一平面上的分振幅斯托克斯参量测量装置,用偏振片和1/4波片组合产生已知的偏振态来定标该装置,用4个性能一致的光电探测器实现快速测量光束的斯托克斯参量.然后用实验系统测量纳米级薄膜样品的入射和反射偏振光的斯托克斯参量,求得椭偏参量ψ和Δ,再求得薄膜样品的厚度d和折射率n.讨论了斯托克斯参量测量的误差问题,最后与常用的消光法椭偏仪作了对比测量实验.测量结果与椭偏消光法比较,d和n的相关系数均大于85%,说明两仪器有很好的一致性.实验研究表明,该方法通过测量入射光和反射光的偏振态,能快速测量纳米级薄膜的参数.系统构建容易,调节方便,定标简单.     

基于光谱干涉椭偏法的薄膜厚度测量

薄膜厚度的测量在芯片制造和集成电路等领域中发挥着重要作用。椭偏法具备高测量精度的优点,利用宽谱测量方式可得到全光谱的椭偏参数,实现纳米级薄膜的厚度测量。为解决半导体领域常见的透明硅基底上薄膜厚度测量的问题并消除硅层的叠加信号,本文通过偏振分离式光谱干涉椭偏系统,搭建马赫曾德实验光路,实现了近红外波段硅基底上膜厚的测量,以100 nm厚度的二氧化硅薄膜为样品,实现了纳米级的测量精度。本文所提出的测量方法适用于透明或非透明基底的薄膜厚度测量,避免了检测过程的矫正步骤或光源更换,可应用于化学气相沉积、分子束外延等薄膜制备工艺和技术的成品的高精度检测。     

类金刚石薄膜光学特性的椭偏法研究

本文采用脉冲电弧离子镀的方法,在p型硅上沉积类金刚石薄膜,用椭偏法测试薄膜的光学常数.根据沉积方法的特点,建立一个四层结构的膜系,并由每一层的吸收情况合理选择色散关系;结合透过率的测试结果,利用光度法给测出薄膜折射率和厚度的估计值,作为椭偏法拟合的初值,拟合效果良好,得到薄膜的折射率、消光系数和几何厚度.     

椭偏测厚法在薄膜包装材料参数测试中的应用

作者对椭偏测厚法数据应用微电脑进行了处理与研究。采用一种求近似解的方法，编程运算得出薄膜材料的折射率和厚度。这种方法应用面广、速度快、精度高，所得结果令人满意。     

疏水型介孔氧化硅薄膜的制备与研究

报道了一种新型疏水型介孔氧化硅薄膜的制备方法.用红外光谱、小角XRD、原子力显微镜对样品进行了表征,并采用椭偏仪和阻抗分析仪测量薄膜的折射率和介电常数.该薄膜具有很低的介电常数和较好的机械强度,是一种可用于微电子工业、极富应用前景的低介电常数材料.     

Cr层厚度对Pd/Cr/Co多层膜光学性质的影响

本文利用磁控溅射的方法生长不同Cr插层厚度的Pd/Cr/Co多层膜,并利用椭偏仪对多层膜的光学常数进行测量.得到了入射光波长在250nm-850nm范围内多层膜的折射率、反射率、吸收系数以及复介电常数的曲线,在此数据的基础上分析了Cr插层厚度对多层膜光学参数的影响.     

透射式外差椭偏测量及非线性误差分析

结合激光外差干涉法和透射式椭偏测量原理,研究了一种快速、高精度测量纳米厚度薄膜光学参数的方法．给出了光学系统设计和理论分析,使用两个声光调制器产生20kHz的差频,直接比较平行分量和垂直分量外差信号的幅值和相位,得到所需要的椭偏参数．光束偏振态的椭圆化及偏振分光不完全所引起的非线性误差是影响纳米薄膜测量精度的主要因素,推导出椭偏参数非线性误差的近似解析表达式,计算结果表明由此导致的膜厚测量误差可达几个nm,相对而言,激光器和反射镜等器件产生的光束椭偏化是其主要原因．     

Closed-form inversion of the reflection ellipsometric function of a film-substrate system: absorbing-substrate optical constant

A closed-form inversion expression for obtaining the optical constant (complex refractive index) of the substrate of an absorbing-film-absorbing-substrate system from one reflection ellipsometry measurement is derived. If, in addition, the film thickness is to be determined, a second measurement at another angle of incidence may or may not be used. The derived formula does not introduce errors itself, and tolerates errors in input variables very well. Random and systematic errors in the measured ellipsometric parameters do not affect the value obtained for the optical constant of the substrate: it is always the true value to two decimal places. Two examples in ellipsometry and in the design of reflection-type optical devices, one each, are presented and discussed. In addition, experimental results for a commercially available wafer are also presented. Two other closed-form inversion expressions for obtaining the optical constant of the substrate from two and three measurements are also presented and briefly discussed.     

超薄四面体非晶碳膜的结构和性能

使用磁过滤阴极真空电弧(FCVA)技术制备不同厚度的超薄四面体非晶碳膜(ta-C)，研究了表征和测量超薄ta-C碳膜微观结构和性能的方法以及膜厚的影响。使用X射线衍射仪验证椭圆偏振光谱仪联用分光光度计表征膜厚度的可靠性并测量了膜密度；用拉曼谱分析薄膜的内在结构，验证用椭偏联用分光光度计表征sp³ C含量的可靠性；用Stoney^，s公式计算了薄膜的残余应力。结果表明，薄膜的厚度由7.6 nm增大到33.0 nm其沉积速率变化不大，为1.7±0.1 nm/min；根据椭偏联用分光光度计的表征结果，薄膜中sp³ C的含量逐渐减少，拓扑无序度降低，与拉曼谱的表征结果一致；厚度为7.6 nm的超薄ta-C碳膜中p³ C的含量最高；随着厚度的增大薄膜中的残余压应力从14 GPa降低到5 GPa；厚度为11.0 nm的薄膜主体层密度最大，为3070 kg/m³，致密性较好；厚度对薄ta-C碳膜表面粗糙度的影响较小。用椭偏和分光光度计测量超薄ta-C碳膜的厚度和表征显微结构是可行的，X射线反射法可用于测量超薄ta-C碳膜密度和表面粗糙度，但是对薄膜的质量要求较高。     

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。     

一种基于波段比值法的海面厚油膜评估方法

激光诱导荧光(LIF)技术是目前较为有效的海面溢油探测技术之一,然而基于该技术的油膜厚度反演算法目前仅适用于薄油膜(≤20μm)。鉴于此,建立了一种基于LIF技术利用油膜荧光信号评估较厚油膜厚度的双波段比值模型,利用油膜荧光光谱的波形特性反演油膜厚度并论证了该算法的适用范围。实验数据得出,当油膜较薄时反演结果误差较大,随着油膜厚度增加误差逐渐降低,当油膜荧光信号趋于饱和时,误差较大且随油膜厚度的增加而快速变大。实验结果表明,该算法可以有效评估200~1400μm范围内的海面溢油油膜的厚度,并可以利用油膜荧光信号的测量相对误差评估该算法的适用范围。     

Optical and electronic characterization of transition layer in thin film Au-GaAs Schottky barrier

The possibility of determination of optical parameters and thickness of interfacial oxide (IO) layer by multiple-angle-of-incidence (MAI) ellipsometry has been studied for Au-IO-GaAs structures with different oxide thickness. The films parameters have been calculated by the original program of inverse ellipsometric problem solution. Parameters of oxide layer have been determined both for free GaAs surface and for that covered by Au film. Gold film was prepared by vacuum evaporation on the heated n-n+GaAs substrate. Its parameters have been determined by MAI ellipsometry and transparency measurements of Au-quartz satellite system. The investigation showed the change of optical parameters of GaAs oxide layer after the Au evaporation. In the assumption of invariable thickness of IO layer its optical parameters are : n = 1.0±0.1, k = 0.4 ÷ 0.6. The mechanism of current transport and electrical parameters of Au-IO-GaAs structures have been determined from I-V and C-V characteristics of Schottky diodes. The results of the determination of transition layer thickness to its dielectric constant ratio (d\_i)) from electrical characteristics of barrier also indicate its difference from initial parameters of oxide layer probably due to interdiffusion of Au, Ga, and As.     

Characterization of polyacrylonitrile films grafted onto nickel by ellipsometry, atomic force microscopy and X-ray reflectivity

The thickness and roughness of polyacrylonitrile films electrografted on a nickel surface have been measured by ellipsometry, atomic force microscopy and X-ray reflectivity. From combined ellipsometry and X-ray reflectivity measurements, accurate values for the refractive indices of polyacrylonitrile and nickel have been derived at a 6328-Å wavelength. Dependence of the film thickness on the monomer concentration has been quantified for the first time. Furthermore, the thickness of the polyacrylonitrile (PAN) film is related to the nature of the solvent, depending on whether it is a good solvent for PAN (dimethylformamide; DMF) or not (acetonitrile; ACN).     

Simultaneous determination of refractive index, extinction coefficient, and void distribution of titanium dioxide thin film by optical methods

The refractive index n(λ) and the extinction coefficient k(λ) of a TiO(2) film prepared by electron-beam evaporation are determined in the spectral region 1.5-5.5 eV. The transmission spectrum of the TiO(2) film on a vitreous silica specimen is inverted to get the k(λ) of TiO(2) in its interband transition region. Above 3.5 eV, k(λ) is used to get the coefficients of the quantum mechanically derived dispersion relation of an amorphous TiO(2). These coefficients and n(∞) are used to determine n(λ). The modeling procedure is applied to spectroscopic ellipsometry data of a TiO(2) film on a c-Si specimen, and the void distribution of the film is revealed. With spectroscopic ellipsometry data above the fundamental band gap, valuable information about surface roughness is obtained. The effective thickness of this rough surface layer is confirmed by an atomic force microscopy measurement.     

Direct numerical inversion method for kinetic ellipsometric data. I. Presentation of the method and numerical evaluation

A direct numerical inversion method for the determination of the refractive index and the thickness of the outermost layer of a thin transparent film on top of a multilayer has been developed. This method is based on a second-order Taylor decomposition of the coefficients of the Abelès matrices of the newly grown layer. The variations of the real-time spectroscopic ellipsometry data are expressed as polynomial fuctions depending on the dielectric constant and the thickness of the newly grown layer. The method is fast, capable of single-wavelength and multiwavelength inversion of continuous as well as discontinuous-index profiles, and can be adapted to many different polarimetric instruments.     

Author index

Very thin organic or polymer films can be analyzed using several analytic techniques. The thickness of the films discussed ranges from monolayers to several thousand ångströms. The techniques described are X-ray photoelectron spectroscopy, IR spectroscopy, ellipsometry and use of the quartz crystal oscillator microbalance. The last technique was applied to a fluoropolymer deposited onto a silver surface. The parameters which control film thickness and unformity are discussed along with how these parameters are measured. The second example discussed is the application of nitrogen-containing organic molecules to copper and iron surfaces. The chemical bonding is discussed along with the orientation of the molecules in the resulting film and the analytical techniques used.