高精度消光式椭圆偏振测厚仪的研究与实现

【作者】 张建彬；

【导师】 黄佐华；

【作者基本信息】 华南师范大学 ， 光学， 2005， 硕士

【摘要】 本文综述了椭偏仪的国内外发展状况,分析了原来HST-1型椭偏仪存在的问题,如测量速度慢、精度不高和ISA接口等,根据消光式椭偏测量原理,采用了USB接口的主从机系统框架,设计了一台高精度反射式消光法椭圆偏振测厚仪样机,并对该仪器进行了大量的测试,测试数据表明该仪器测量精确度高且速度快。主要完成了以下的工作: 1、光机系统采用模块化的设计,便于组装成立式或卧式椭偏光机实验系统; 2、采用USB接口的主从机工作方式,解决了HST-1型椭偏仪的ISA接口应用困难的问题; 3、基于“电流矢量恒幅均匀旋转”的步进电机细分技术,设计了步进电机均匀细分驱动电路,采用软件生成表和人工修正相结合的方法,补偿了步距角与细分数的非线性关系,实现了步距角的均匀细分,细分步达到0.025°; 4、设计和编写了从机测控软件、主机控制软件和椭偏数据处理软件; 5、提出了“周期步进计数法”,提高了起、检偏器机械定位的准确性和稳定性; 6、对于消光点的寻找,采用“等值点对平均法”,消除噪声干扰对消光点的影响,使最终消光点的寻找具有较高的准确性和稳定性; 7、提出了“光学角度与机械角度分离法”,解决了原来在机械零位附近的小角度消光点测量中经常出现的偶然误差; 8、实现了起、检偏器透光轴入射面方向的自动寻找,角度误差小于0.025°; 9、提出了“遍寻迭代计算法”,实现高精度、快速和稳定的椭偏参数处理; 10、对本系统的性能进行了全面而系统的测试,测试实验结果更多还原

【Abstract】 with a comprehensive study on the development of ellipsometer both at home and abroad as well as an analysis of the problems undermining HST-1 ellipsometer such as low effeciency in measuring, poor precision and ISA, this paper applies the master-sercice framework with USB interface into the designing of a precise reflectional null ellipsometer according to the principles by which the null ellipsometer works. Meanwhile this paper focuses on its actual measurement, and the result shows that the newly-designed instrument shows brilliance in precison and speed. The following is what has been done in this thesis:1 The designing of the optics-mechanics system is done in terms of 6 modules, which provides convenience for installing both erect and level structures in the ellipsometer;2 The master-slave framework with USB interface is adopted to eliminate the application difficulty of ISA interface;3 Based on the subdivision technology of evenly-rotating step motor powered by current vector with constant amplitude, this paper designs driving circuit for step motor,which is evenly as well as precisely divided. The designing combines data table generated by computer and manual adjustment so as to obtain the linearity between the step angle and the number of subdivided steps. Thus, the subdivision angle is close to 0.025° ;4 The software for the measuring of slave instrument, for the operating interface of master and data processing of the ellipsometric parameters are well disigned and programmed;5 "Circulational Step-counting" proposed in this thesis improves the location of polarizer and analyzer in terms of precision and stablization;6 "Average Value of the 2 Points at the Same Level" functions effeciently in getting the nulling angles free from noise so as to help a lot in seeking the nulling angles as well as improve the stablization and precision of the last action;7 "The Separation of Optical Angle from Mechanical One" isproposed, and as a result,the random errors that often happens in measuring the nulling angles near mechanical zero have been diminished;8 The automatic seeking into optical zeroes of polarizer and analyzer is realized with the angle error less than 0.025° ;9 The proposition of "Iterative Computing with Ransacking Power" processes the ellipsometric parameters with high precision , speed and stablization;10 A sound testing of the very system shows that the newly designed instrument exerts brilliance in precision and speed;11 A discussion about the reduction of errors is also proceeded in this paper;更多还原