Novel scheme of ellipsometry utilizing parallel processing with arrayed photonic crystal

We propose a novel static parallel-processing ellipsometer consisting of arrays of photonic crystal polarizers and quarter-wave plates (QWP) having different orientations of the optical axes. On the basis of the autocloning technique, each array is monolithically integrated on a substrate in a single deposition process. The pattern of light transmitted through the two photonic crystals, a number of pairs of QWP, and polarizer with different axes is detected by an array of photodiodes, and the polarization is analyzed instantaneously from the image. No mechanical rotation or electrooptic modulation is necessary. Preliminary experiments of the ellipsometer are performed for the first time, and the principle of operation is confirmed. This type of ellipsometer is simple, compact, and robust, and therefore, will open up new applications for industrial use.     

基于Mueller矩阵成像椭偏仪的纳米结构几何参数大面积测量

为了实现有效的工艺监控, 在批量化纳米制造中对纳米结构的关键尺寸等几何参数进行快速、低成本、非破坏性的精确测量具有十分重要的意义. 光学散射仪目前已经发展成为批量化纳米制造中纳米结构几何参数在线测量的一种重要手段. 传统光学散射测量技术只能获得光斑照射区内待测参数的平均值, 而对小于光斑照射区内样品的微小变化难以准确分析. 此外, 由于其只能进行单点测试, 必须要移动样品台进行扫描才能获得大面积区域内待测参数的分布信息, 从而严重影响测试效率. 为此, 本文将传统光学散射测量技术与显微成像技术相结合, 提出利用Mueller矩阵成像椭偏仪实现纳米结构几何参数的大面积快速准确测量. Mueller矩阵成像椭偏仪具有传统Mueller矩阵椭偏仪测量信息全、光谱灵敏度高的优势, 同时又有显微成像技术高空间分辨率的优点, 有望为批量化纳米制造中纳米结构几何参数提供一种大面积、快速、低成本、非破坏性的精确测量新途径.     

A high precision,polychromatic, automatic ellipsometer

The design and performance of a versatile, high precision, automatic ellipsometer, which follows rapid changes in surface properties, scans through the entire visible spectrum and through angles of incidence between 50° and 89°, is described. The state of polarization of the light beam is phase and amplitude modulated by means of two Faraday modulators working at a single frequency but in quadrature. Out-of-balance error signals are electronically processed and applied to a servodrive system which rotates the polarizing elements to the null positions. The angular positions of the prisms are measured by means of moiré fringe-counting systems which have digital displays reading to 0.001° over a range of 360°. The absolute accuracy of measurement of Δ and ψ, once all effects of intrinsic component imperfections and misalignments have been minimised, is better than ±0.013° in ψ and ±0.014° in Δ. The ellipsometer has been shown to work satisfactorily for a wide range of surface problems and in particular for surfaces with reflectivities as low as 0.001. The mechanical construction of the ellipsometer allows simultaneous movement of the two optical arms in opposite directions hence allowing a change in angle of incidence to be effected without any sample realignment. The ellipsometer has been designed with a sufficiently large sample space to allow the inclusion of bulky environmental chambers such as cryostats or vacuum systems and may be used to examine either vertical or horizontal surfaces.     

Polarization modulation imaging ellipsometry for thin film thickness measurement

A polarization modulation (PM) imaging ellipsometer is proposed and setup in order to measure precisely the thickness of thin film. Five images are collected sequentially by CCD camera with respect to five pre-determined azimuth angles of a quarter wave plate (QWP) during measurement. Then two-dimensional (2-D) distributions of the ellipsometric parameters ψ and Δ over the full dynamic range are obtained. Conceptually, PM imaging ellipsometer integrates the features of phase shift interferometry with conventional photometric ellipsometry by rotating the QWP sequentially to produce polarization modulation that is able to measure the thickness of a thin film in two dimensions precisely and quickly. The basic principle of PM imaging ellipsometer is derived wherein features such as common path configuration, full dynamic range of measurement, and insensitive to non-uniform response of the CCD are analyzed. The experimental results verify the ability and performance of PM imaging ellipsometer on 2-D thin film thickness, while the errors regarding the ellipsometric parameters measurements are discussed.     

Phase-based method in heterodyne-modulated ellipsometer

A new common-path heterodyne-modulated ellipsometer with two-phase detection to measure the ellipsometric parameters of amplitude ratio (Ψ) and phase difference (Δ) between p- and s-polarizations of the thin film isotropic materials is proposed. Uniquely, the new scheme distinct from the other previous studies is only by taking two phases from heterodyne signals. Thus, the proposed system is a phase-sensitive modulated ellipsometer that can have the ability to measure the full range of the ellipsometric parameters with high sensitivity and eliminate the intensity fluctuation in system. The ability and performance of modulated ellipsometer on measurement of thin film thickness and ellipsometric parameters are verified by experiments. The errors regarding the ellipsometric parameter measurements are also discussed. The experimental results show that the average standard variation of measured ellipsometric parameters (Ψ and Δ) and the thickness measurement of silica thin film deposited on silicon substrate are 0.13°, 0.94°, and 0.55 nm, respectively. Accordingly, this new idea can be applied to measure isotropic thin film with extremely high absorbance that results in the poor signal/noise ratio in contrast extraction from heterodyne signals.     

与消光式兼容的光度椭偏仪的原理

在PQSA式消光型椭偏仪基础上,把原来方位固定的1/4波片改为旋转波片就可以构成与消光式兼容的新型光度椭偏仪。本文讨论了这种光度椭偏仪的工作原理和计算公式。理论分析指出,这是一种完全的椭偏仪,能唯一地确定的符号,并在测量线偏光的时精度不会下降。文中还报告了进行原理性实验的结果。     

MathCAD在椭圆偏振仪测定薄膜光学常数中的应用

薄膜光学常数决定薄膜的光学性能。通过对椭圆偏振仪测试原理的分析,得到求解薄膜光学常数超越方程的数值算法简化公式,并利用MathCAD的“Solve Block”模块开发了基于Windows系统的椭圆偏振测量薄膜光学常数的计算程序,该程序可用于单层有吸收薄膜或无吸收薄膜折射率和厚度的计算。实际应用结果表明,该计算具有数值准确、精度高、运算速度快、适应性好,对系统无特殊要求等优点,可用于薄膜制备过程的在线检测。     

高校椭偏测厚实验的计算机辅助教学

分析了高校椭偏测厚实验中存在的问题，成功研制出具有教学特点的多功能智能椭偏测厚仪和编制了一套该实验的CAI课，实验表明：椭偏测厚实验的计算机辅助教学效果良好。     

Ellipsometry without a compensator - two improvements in speed and reliability of the Monin and Boutry method

Theoretical and experimental aspects of two new procedures applied to the Monin and Boutry ellipsometer arrangement are described. One of those modifications enables quicker measurements, and the other increases the consistency of results.     

Dual-frequency paired polarization phase shifting ellipsometer

A novel dual-frequency paired polarization phase shifting ellipsometer (DPPSE) is proposed and experimentally demonstrated. It combines the features of the phase shifting interferometer and common-path polarized heterodyne interferometric ellipsometer where the ellipsometric parameters (EP) of a specimen are measured accurately. The experimental results verify that DPPSE is capable of determining the full dynamic range of EP. In addition, the properties of dual-frequency paired linearly polarized laser beam in DPPSE perform in common phase noise rejection mode. It is insensitive to environmental disturbance and laser frequency noise. The capability of DPPSE to perform higher accuracy EP measurement than conventional ellipsometer is verified according to error analysis.     

Generalized ellipsometry and the 4 × 4 matrix formalism

The 4 × 4 matrix formalism described by Berreman and others provides a method of determining the reflection and transmission properties of general stratified anisotropic materials. This formalism, when combined with the work of Azzam and Bashara and others on generalized ellipsometry, can be used to predict the extinction settings of a nulling ellipsometer for reflection of light from virtually any type of film covered surface provided that the surface is flat and that any films are uniform. In the present work the 4 × 4 matrix formalism is reviewed and combined with the equations necessary to predict the null settings of an ellipsometer. Examples of the application of these calculations to an optically active surface and a biaxial surface are also presented.     

用椭偏法分析单波段及双波段兼容a－C：H增透膜

讨论了在单晶锗上为获得单波段（３～５μｍ）及双波段（３～５μｍ、８～１２μｍ）兼容ａ－Ｃ：Ｈ增透膜所必需的膜系设计，及用椭偏法对该膜进行的增透结果分析。结果表明，ａ－Ｃ：Ｈ膜是理想的红外增透膜。椭偏法对分析所制备的膜是否符合膜系设计要求及沉积工艺参数的确定具有重要意义。     

不同热处理的GeTe薄膜的光学参数测量

运用一种新的测量单面镀膜膜层光学参数的方法，对不同热处理的ＧｅＴｅ半导体薄膜样品的光学参数进行了测量，准确地获得了被测薄膜材料的光学参数，并采用椭圆偏振光谱测量作比较研究。经此为基础，对用椭偏仪测得的数据进行拟合计算，得出了样品材料在２５０～８３０ｎｍ波段范围的复折射曲线。     

Method for measuring the phase shift introduced by a phase plate with an interference ellipsometer

A new method for measuring the phase delay introduced by a phase plate is substantiated. The method uses an interference ellipsometer that does not require preliminary determination of the direction of the principal axes of the plate. Sources of error in the method are analyzed and components of error are quantitatively estimated. Requirements for the polarization characteristics of a beamsplitter used in the interference ellipsometer are formulated and conditions for decreasing the measurement error are found.     

Imaging method of single layer graphene on metal substrate based on imaging ellipsometer with large field of view

Single layer lattice graphene deposited on the metal substrate can hardly be imaged by the optical microscope. In this Letter, a large field-of-view imaging ellipsometer is introduced to image single layer graphene which is deposited on a metal substrate. By adjusting the polarizer and the analyzer of imaging ellipsometer, the light reflected from surfaces of either single layer graphene or a Au film substrate can be extinguished, respectively.Thus, single layer graphene can be imaged correspondingly under brightfield or darkfield imaging modes. The method can be applied to imaging large-area graphene on a metal substrate.     

Effects of various ambient-aging processes in chopped and non-chopped optical films

The effects of various ambients on the non-chopped and chopped films of cryolite, MgF₂ and mixed cryolite-MgF₂, as measured by ellipsometer, are reported. The moisture decreases the refractive index whereas an increase is observed in air and other ambients. In all the ambient-aging the chopped films show smaller changes (nearly half) in refractive index than non-chopped films. Aging seems to be due to three main processes, a long-term adsorption-like surface reaction and two short-term reactions.     

各向异性表面的椭偏测量的消光过程

本文描述了在正向入射条件下,当待测的各向异性反射面(如全息光栅)的两个笛卡儿本征矢方向与系统的指向有微小偏离时,椭偏测量的消光过程由理想的两步过程转变成多步过程。文中同时定量指出该偏离所造成的影响及应用。     

Optimizing Film Design and Application for the Recordable Compact Disk Developed by Two Cyanine Dye Samples

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Optimizing Film Design and Application for the Recordable Compact Disk Developed by Two Cyanine Dye Samples

The optical constants of two cyanine dye films we prepared have been measured by a RAP-1 typed spectroscopic ellipsometer. On the basis of making a simplified model for the wafers of a recordable compact disk (CD-R), the optimizing designs for them developed by the cyanine dye films are given. In addition, the dynamic storage performances of two sample disks have been tested by our dynamic storage testing system. Measurement results of the sample disks are obtained to test our film designs.     

Annealing effects on the structural and electrical transport properties of n-type Bi2Te2.7Se0.3 thin films deposited by flash evaporation

N-type Bi₂Te_2.7Se_0.3 thermoelectric thin films with thickness 800 nm have been deposited on glass substrates by flash evaporation method at 473 K. Annealing effects on the thermoelectric properties of Bi₂Te_2.7Se_0.3 thin films were examined in the temperature range 373-573 K. The structures, morphology and chemical composition of the thin films were characterized by X-ray diffraction, field emission scanning electron microscope and energy dispersive X-ray spectroscopy, respectively. Thermoelectric properties of the thin films have been evaluated by measurements of the electrical resistivity and Seebeck coefficient at 300 K. The Hall coefficients were measured at room temperature by the Van der Pauw method. The carrier concentration and mobility were calculated from the Hall coefficient. The films thickness of the annealed samples was measured by ellipsometer. When annealed at 473 K, the electrical resistivity and Seebeck coefficient are 2.7 mΩ cm and −180 μV/K, respectively. The maximum of thermoelectric power factor is enhanced to 12 μW/cm K².