【作者】 王海珊；

【导师】 史铁林； 刘世元； 廖广兰；

【作者基本信息】 华中科技大学 ， 机械制造及其自动化， 2008， 博士

【摘要】 干涉显微法是一种基于光学干涉原理的表面形貌测量方法,具有测量速度快、精度高、非接触的优点,主要用于MEMS等基于IC平面工艺制造的微纳结构表面形貌及其运动的测量。本文通过深入研究干涉显微法原理,对相移干涉法(PSI)和垂直扫描干涉法(VSI)的数学模型和算法进行了分析比较,提出了VSI相位包络算法,并且在频闪干涉视觉三维测量系统的基础上,完成了干涉显微测量的关键技术研究及系统实现。根据Michelson干涉仪模型,对光学干涉法的数学模型进行了推导分析,确定了干涉光强函数与包络函数和相位函数之间的关系,得到了PSI和VSI测量方法的理论模型。在此基础上,通过分析研究目前主要的PSI和VSI算法原理,利用干涉光强函数及其Hilbert变换函数的频谱分布特点,提出了相位包络算法。该算法应用采样定理,利用Whittaker波形重构原理计算采样点的包络值和相位值,从中提取干涉光强函数的零光程差位置,得到样品表面各点的相对高度值。仿真结果表明,相位包络算法的具有较高的测量精度。在频闪干涉视觉三维测量系统的基础上,设计开发了一套集PSI和VSI测量模式为一体的干涉显微测量系统。系统采用Linnik结构干涉显微镜,利用LED和窄带滤波片实现PSI和VSI的光源切换,通过参考镜扫描的方法将VSI扫描器与PSI相移器集为一体,实现PSI和VSI测量硬件的统一集成。在频闪干涉视觉测量软件中增加了VSI测量模块,可以用相位包络算法、五步相移算法、空间频域算法、SEST算法对VSI采样数据进行处理,并改进了表面形貌测量结果存储文件的格式。对频闪干涉视觉三维测量系统的误差现象进行了分析,研究了Linnik结构干涉显微镜在PSI测量中的误差机理。根据平面样品的测量结果,可以确定系统在PSI测量中存在一个近似于二次曲面的误差面,通过研究PSI测量过程中误差产生机理,建立了相移误差、摄像机成像误差以及光波阵面匹配误差模型。根据误差模型的特点,对系统进行了改进,设计了以标准平面作为测量样品的相关实验,验证误差模型与误差曲面分布之间的关系。实验结果表明,光波阵面匹配误差中Linnik结构干涉显微镜的两个显微物镜后焦点误差是产生误差曲面的主要原因。在误差分析的基础上,利用标准平面样品的测量结果,对PSI测量进行了补偿,取得了较好的补偿效果。系统采用两种LED光源对美国VEECO公司的标准台阶做了测量,比较了两种LED光源和不同处理算法下的台阶测量结果,通过分析相位谱误差对包络的影响,对测量结果中相位包络算法和空间频域算法的测量误差进行了研究,并且应用双峰值和特征参数对相位包络算法进行了修正。更多还原

【Abstract】 Microscopic Interferometry technique is a profilometry measurement technology for micro-nano structure surface profile and has been employed widely in the static and dynamic measurement of Micro-electronics and Micro Electronic Mechanic System for its non-contact, fast speed and high accuracy. By studying the interferometry and micro-vision principle, this dissertation discuss the model and interference processing algorithm of Phase Shift Interferometry (PSI) and Vertical Scanning Interferometry (VSI) which are the main techniques of the microscopic interferometry technique, and developed a new VSI interference processing algorithm, Phase Envelop algorithm. On the basis of previous Stroboscopic Interferometry and Micro-vision System, some key technologies of microscopic interferometry technique are realized.The model of light interferometry was deduced from the Michelson interference model, and the equation of light interference intensity function, envelop function and phase function was confirmed, from which the PSI model and VSI model were infered. On the basis of these studies, the Phase Envelop algorithm was presented, which extract the position of zero optical path difference of light interference intensity function from the phase and envelop values of sample points, which could be calculated by Whittaker reconstructed technique of sampling theory based on the spectrum of light interference intensity function and its Hilbert transform function. The outcome of computer simulation verified that the Phase Envelop algorithm has a high precision in the measurement.On the basis of the Stroboscopic Interferometry and Micro-vision system a profilometer system was developed for micro-nano structure profile testing which could operate in either PSI mode or VSI mode. The light source is a broadband LED which could switch to a narrowband light source by a filter to satisfy both interferometry mode. A Linnik interferometer was adopted in this profilometer, in which the scanner and the phase shifter were integrated through scanning the reference mirror. The VSI software module was added in the Stroboscopic Interferometry and Micro-vision System software and could process sampling interference intensity data by Phase-Shifting algorithm, SEST algorithm, Spatial Frequency Domain algorithm and Phase Envelop algorithm, and an effective file format was proposed to store the three-dimensional surface profile data.The error mechanism of Linnik Interferometer in PSI measurement was studied by analyzing the error phenomena in the PSI measurement of the Stroboscopic Interferometry and Micro-vision System in which a measure error approximated to a conicoid was discovered. On the basis of PSI error mechanism study, the phase-shift error, camera error and optical wave matching error models were presented and some experiments were projected in which the plane was selected as the sample. The outcome of these experiments verified that the optical wave matching error was the main error source and the conicoid error was mainly caused by the focus axial matching error of the objectives in Linnik Interferometer. So the standard plane measurement could be used to compensate the outcome of PSI measurement.The standard step height of VEECO Corp. was measured by this system which employed two LED light source, and the experimental results which were processed by different VSI algorithm described above, were compared and analyzed. The error of Spatial Frequency Domain algorithm and Phase Envelop algorithm in the measurement were studied based on the analysis of phase spectum error and Phase Envelop algorithm was modifyed by two peak sum character.更多还原