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。     

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.     

一种高精度低漂移电子积分器的设计

讨论了由运算放大器构成的理想电子积分器的工作原理,分析了积分漂移、积分时间常数等主要因素对积分输出误差的影响及改善措施。设计了一种测量灵敏度高达10-9 C新型电子积分器,并将该电子积分器应用于10-7C～10-8C电量微磁通信号测量系统,通过实际测量数据证明,该积分器可实现对瞬变小信号进行高精度的测量。测量精度达到满量程小于1.5%,分辨率为0.5%,而且该设计方案结构简单、灵敏度和精度高、经济性好,有很好的推广使用价值。     

Immunosensor for detection of Yersinia enterocolitica based on imaging ellipsometry

An immunosensor for the detection of pathogens was developed using imaging ellipsometry (IE) as a detection method. Yersinia enterocolitica was selected as the target pathogen in this study. A gold surface deposited with a self-assembled layer of 11-mercaptoundecanoic acid (11-MUA) was used as a substrate. For the fabrication of the immunosensor, protein G spots were made on the substrate using an inkjet-type microarrayer, and monoclonal antibody (Mab) was adsorbed onto the protein G spots. Deposition of each layer onto the substrate was confirmed by the measurement of surface plasmon resonance. The ellipsometric image of the protein G spot and the Mab-adsorbed protein G spot were acquired using an off-null ellipsometry type of imaging ellipsometry system. By measuring the ellipsometric angles of the protein layers, the surface concentration of each protein layer was calculated. The change in the mean optical intensity of the protein spot to the various concentrations of Y.enterocolitica was estimated. The immunosensor using imaging ellipsometry could successfully detect Y. enterocolitica in concentrations varying from 10(3) to 10(7) cfu/mL. The proposed immunosensor system has the advantage of allowing label-free detection, high sensitivity, and operational simplicity.     

Application of the Tauc-Lorentz formulation to the interband absorption of optical coating materials

Recent progress in ellipsometry instrumentation permits precise measurement and characterization of optical coating materials in the deep-UV wavelength range. Dielectric coating materials exhibit their first electronic interband transition in this spectral range. The Tauc-Lorentz model is a powerful tool with which to parameterize interband absorption above the band edge. The application of this model for the parameterization of the optical absorption of TiO2, Ta2O5, HfO2, Al2O3, and LaF3 thin-film materials is described.     

Study of a Thermophysical System with Two Time Constants Using an Open Photoacoustic Cell

In this paper a study of a thermophysical system with two time constants, an electronic time constant and a thermal relaxation time constant, is presented. The system under study is a thin metallic sample coupled to an open photoacoustic (PA) cell, the resulting signal being measured by a lock-in amplifier or by a data acquisition device. All operations are performed by a computer-based automatic measurement system. A time- and frequency-domain theoretical analysis of the photothermal signal is given combining the usual PA scheme to the energy balance equation of the system. The experimental results are in very good agreement with the developed theory.     

脉冲电压信号测量系统

随着电子技术的发展,半导体开关元件的切换频率不断提高。为了检测开关元件在快速切换开关时产生的脉冲电压信号,本文讨论了窄脉冲信号检测的原理和方法,设计并实现了脉冲测量电路。该电路分别采用高速ADC和DDR2存储器进行波形采集和存储,并在FPGA中设计检测电路,通过信号同步触发的形式实现窄脉冲信号的实时检测。实验表明:系统能够有效捕获到脉宽为100纳秒级的信号,且具有较高的幅度精度以及良好的实时性。同时,预触发长度可以通过编程实现。     

A Microcomputer-Based System for Area Measurement

An electronic system developed for area measurement is described. A standard X-Y recorder specially adopted with a light pen was made to scan the area under test and give a TTL logic signal that changes state whenever the area circumference is crossed. From such information the microcomputer is programmed to calculate the area using Simpson's rule and display the result on a seven-segment display. Sources of error in measurement and its nature are investigated. Modifications in the basic system to reduce the error are included. The designed system can also be used for determining the perimeter and locating the centroid of an object.     

双侧电子引伸计的原理和误差分析

首先对单侧电子引伸计测量结果不稳定及误差较大的原因进行了分析,然后对双侧电子引伸计的测量原理进行了介绍,建立了斜线伸长量与拉伸试样轴向伸长量之间的关系,证明了双侧电子引伸计的测量结果不受偏心拉伸的影响,其系统误差很小甚至可以为零。     

电子政务绩效评估及其机理研究

从评估内容层次化、评价体系动态化等7个方面分析了电子政务绩效的评估机理,并在5种主流基本评估模式基础上,提出了电子政务绩效的3种基本评估类型 ;按照构建指标体系、确定评估标准或理想模式、建立权重体系、采集与处理评估数据、评估分析与综合、撰写和提交评估报告6方面内容理顺了电子政务绩效的评估流程,并从电子政务信息资源有效整合和共享的角度,讨论了评估资源的整合及其标准化问题.     

Numerical techniques useful in the practice of ellipsometry

While well-established methods for sample preparation and measurement make ellipsometry attractive for surface and film investigations, development of reliable methods for computing unknown physical attributes of reflecting surfaces is just beginning. This situation has arisen because the equations of ellipsometry are transcendental, have not been inverted and thus require numerical techniques for solution in all but the simplest of reflecting surface configurations. The problem of data analysis is by no means solved and remains one of the key issues in ellipsometry. This paper presents a survey of numerical techniques and principles for approximating solutions to problems, and illustrates an application of these techniques in the development of a new algorithm to address the problem.     

Determination of Ratio of Complex Eigenvalues of Optical Systems with Known Eigenpolarizations by Ellipsometry

Surface ellipsometry involves measurement of the ratio of eigenvalues (reflection coefficients) associated with the orthogonal linear eigenpolarization parallel and perpendicular to the plane of incidence. This paper shows that the ratio of complex eigenvalues of any optical system with known arbitrary eigenpolarizations can be determined, with equal ease, using the same ellipsometer arrangements of surface ellipsometry. Expressions are derived that give the ratio of eigenvalues as a function of (1) the Cartesian complex polarization variables that describe the eigenpolarizations, (2) a set of nulling angles in the symmetrical PC₁SC₂A or asymmetrical PCSA and PSCA ellipsometer arrangements, (3) the slow-to-fast complex relative transmittance of the compensator(s). The results are applied to the ellipsometric measurement of optical rotatory dispersion and circular dichroism.     

A High Sensitivity Microwave Sampling System with Adaptive Time-Drift Compensation

A new microwave sampling system is presented whose sensitivity has been increased by digital processing of the measurement data. The signal processing gets more complicated due to a time drift caused by electronic circuits in the sampling oscilloscope. An adaptive method to compensate for this time drift has been developed. The influence of noise is discussed, giving the remaining time uncertainty as a function of the signal-to-noise ratio. Finally an example illustrates how this method can be applied in an automatic sampling system.     

射流电子水表原理及流量测量特性研究

介绍了基于恒磁励磁电磁检测方法的射流电子水表,研究了其结构原理、主要技术特征、流量测量特性、以及传感与信号处理技术。针对射流电子水表小流量测量特性,提出了降低射流计量腔的起振阈值,改进了电磁传感原理检测射流振荡信号的方法。经射流电子水表批量生产验证,证明了改进小流量特性思路和方法的有效性。     

虚拟仪器在导弹测试发控系统中的应用

设计的基于PC/104嵌入式计算机系统的虚拟仪器,具有测量各种电学信号和时频信号功能;同时具有输出各种模拟信号、不同频率和幅值的脉冲信号及各种波形信号的信号源功能.其测量精度高,输出信号精度高,可用于导弹测试发控系统对其进行各种测试和控制.     

电子式电流互感器校验方法研究

提出一种校验电子式电流互感器模拟量输出和数字量输出的方法,该方法基于采样测量技术,测量标准电流互感器和被校电子式电流互感器的二次输出,比较二者的差异得到被校电子式电流互感器的比值误差和相位误差。详细分析了电子式电流互感器模拟量输出及数字量输出校验方法的测量误差,论证了该方法的合理性和可行性。根据该方法研制的校验装置样机在国家高电压计量站进行了校准测试,测试结果表明,所研制的校验装置满足校验0.2及以下等级计量用电子式电流互感器的准确度要求。     

Development of a polarimetric optical fiber sensor for electronicmeasurement of high pressure

The theoretical understanding of the principle of pressure-induced polarization coupling is discussed, and the improved construction, operation, and temperature desensitization of a high-pressure (up to 100 MPa) fiber-optic sensor in two configurations is described. The sensor exploits the effect of polarization coupling between two orthogonally polarized eigenmodes of a highly birefringent, polarization-preserving optical fiber which serves as the sensing element. An idea of temperature desensitization of the sensor output signal is demonstrated. The requirements for an electronic measurement system based on the sensor are discussed, including indentification of the parametric and functional specifications and constraints of such a system     

Analytical solutions of the azimuthal deviation of a polarizer and an analyzer by polarizer-sample-analyzer ellipsometry

The analytical solutions of the azimuthal deviation of a polarizer and an analyzer were obtained by polarizer-sample-analyzer ellipsometry with a three-intensity measurement technique. By performing two sets of this three-intensity measurement with the polarizer's azimuth set at 45 degrees and at -45 degrees , we were able to obtain a set of ellipsometric parameters free from the azimuthal deviations of the polarizer and the analyzer.     

Errors and uncertainties in the measurement of ultrasonic wave attenuation and phase velocity

This paper presents an analysis of the error generation mechanisms that affect the accuracy of measurements of ultrasonic wave attenuation coefficient and phase velocity as functions of frequency. In the first stage of the analysis we show that electronic system noise, expressed in the frequency domain, maps into errors in the attenuation and the phase velocity spectra in a highly nonlinear way; the condition for minimum error is when the total measured attenuation is around 1 Neper. The maximum measurable total attenuation has a practical limit of around 6 Nepers and the minimum measurable value is around 0.1 Neper. In the second part of the paper we consider electronic noise as the primary source of measurement error; errors in attenuation result from additive noise whereas errors in phase velocity result from both additive noise and system timing jitter. Quantization noise can be neglected if the amplitude of the additive noise is comparable with the quantization step, and coherent averaging is employed. Experimental results are presented which confirm the relationship between electronic noise and measurement errors. The analytical technique is applicable to the design of ultrasonic spectrometers, formal assessment of the accuracy of ultrasonic measurements, and the optimization of signal processing procedures to achieve a specified accuracy.     

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.