【作者】 常素萍；

【导师】 谢铁邦；

【作者基本信息】 华中科技大学 ， 测试计量技术及仪器， 2007， 博士

【摘要】 随着表面测量技术的发展,表面的三维测量和评定已经成为研究的重点。接触式和光学探针式测量仪器大多是逐点扫描,在三维表面测量的应用中受到一定限制。垂直扫描白光干涉测量技术具有高精度、大量程、无相位模糊等特点,而且为面扫描,测量效率高,是一种较为理想的超光滑表面的三维形貌测量方法,已开始在表面微观形貌测量中应用,特别是有阶梯、沟槽等不连续表面的微电子器件和光学器件的表面特征测量。本文根据垂直扫描白光干涉的特点,提出了一种基于白光零级干涉条纹跟踪法测量三维表面的绝对坐标值的新方法,突破白光干涉显微物镜视场的限制,可实现大量程大范围的三维表面轮廓测量。在具有垂直扫描功能的三维测量工作台的基础上,研制出垂直扫描白光干涉三维表面轮廓测量系统,同时满足形貌测量和轮廓尺寸测量的要求。本文的主要内容和创新点如下:(1)提出了一种基于垂直扫描白光零级干涉条纹跟踪法测量三维表面轮廓的绝对坐标值的方法,该方法已被国外专家认可。建立了白光干涉显微技术的测量模型,分析了光源带宽、数值孔径、曲面斜率对白光干涉条纹的光强分布的影响。(2)研制了一种基于垂直扫描白光干涉测量表面微观形貌和垂直扫描白光零级干涉条纹跟踪法测量表面三维轮廓的垂直扫描白光干涉三维表面轮廓测量系统,测量系统的主要技术指标为:垂直测量范围:8mm;垂直扫描分辨率:0.002μm;水平测量范围:40mmX40mm;水平位移分辨率:0.2μm;显微物镜放大倍数:40X;显微物镜数值孔径:0.65;横向分辨率:0.52μm;微观形貌重复性测量误差小于5%;轮廓测量误差小于2%。(3)研制了适用于垂直扫描白光干涉三维表面轮廓测量系统的高精度、大量程三维测量工作台。三维测量工作台的垂直扫描位移机构采用了共衍射光栅计量系统,伺服电机和压电微驱动器分别驱动的粗、精两级定位机构,满足垂直扫描白光干涉跟踪原理测量表面轮廓的要求,该垂直扫描位移机构已申请发明专利(申请号:200510018618.1);水平位移机构采用共基面结构,伺服电机驱动,衍射光栅计量系统控制定位。通过双频激光干涉仪对三维测量工作台的位移性能进行定量分析,三维测量工作台垂直方向的扫描范围为8mm,扫描分辨率0.002μm;水平位移范围为40mm×40mm,位移分辨率0.2μm;平面运动误差小于0.2μm。(4)系统研究了白光干涉算法及其误差因素,提出线性拟合包络线算法。同时针对垂直扫描白光干涉法测量涂有透明介质的表面时出现的双干涉条纹进行了分析,并且根据双干涉条纹的干涉相干图特点,提出了干涉条纹的双干涉条纹分离算法。(5)开发了表面三维轮廓测量和评定软件分析系统,用于表面微观形貌的垂直扫描白光干涉测量和基于垂直扫描白光零级干涉条纹跟踪原理的三维表面轮廓测量,介绍了相应的数据处理方法和参数评定体系,给出了测量实例。更多还原

【Abstract】 With the development of surface measurement technology, more attentions are focused on the surface measurement and evaluation in three dimensions. The point-scanning mode of the contact measurement instruments and the optical probe instruments limit their applications in three dimensional surface measurements. With the advantages of high-precision, large and unambiguous measurement range, and the line-scanning mode, vertical scanning white-light interferometric technology had been thought as a preferable method to measure super smooth surface in three dimension, and began to be applied for the surface measurements of micro-electronic component and optical component with such discontinuous characteristic as step, groove. Based on vertical scanning white-light interferometric characteristic, a new method for the absolute ordinate measurement by tracing the zero-order fringe is proposed in this dissertation. The new method broke through the limitation of the viewfield of microscope objective to measurement area, which could accomplish the large-range and large area measurement of three-dimensional surface. A surface profile measurement system for three-dimensional surface is also developed to meet the requirement of shape and profile dimension.Main outlines and innovations of this dissertation include:(1) A method for the absolute ordinate measurement by tracing the zero-order fringe based on the vertical scanning white-light interferometric technology is proposed. The model for white-light interference microscope is derived, which is helpful to analyze the influences of the bandwidth of light source, numerical aperture (NA) of microscope objective, the slope of the measured surface on the intensity contribution of white-light interference fringe.(2) A surface profile measurement system for three-dimensional surface is developed based on vertical scanning white-light interferometric measurement method and the zero-order fringe tracing method for the large-range and large area measurement of surface shape. Its measurement range is 8mm, and scanning resolution is 0.002μm in the vertical direction; while the measurement range is 40mm×40mm and the resolution is 0.2μm in the horizontal X-Y direction. The microscope objective has the magnification of 40, NA of 0.65, and the lateral resolution of 0.52μm. The repeatable measurement error for the surface profile is less than 5%, and the measurement error for the surface shape and dimension is less than 2%.(3) A three-dimensional measurement stage with a high precision and a large displacement range is developed for the surface profile measurement system. In this stage, two-grade positioning accomplished by vertical scanning displacement function mechanism with the common standard measuring system and driven by servo-motor and piezo-electronic transducer respectively, which meets the requirements to measure large range surface according to the zero-order interference fringe tracing measurement method. An invention patent for this mechanism has applied (Patent application number: 200510018618.1). The horizontal displacement mechanisms with the common baseplane are driven by servo-motor and are controlled by diffraction grating standard measuring system. The displacement performance of three-dimensional measurement stage is calibrated by double-frequency laser interferometry. Its displacement range is 8mm, and displacement resolution is 0.002μm in the vertical direction; its displacement range is 40mm×40mm and the resolution is 0.2μm in the horizontal X-Y direction; the plane error is less than 2μm.(4) The white-light interference extracting algorithms and the influences to their extracting precision are analyzed, and a linearly envelope fitting algorithm is proposed. The phenomenon of double fringe caused by the surface covered with transparent film is analyzed, and the fringe separating algorithms are developed according to its characteristic of correlogram.(5) A measurement and evaluation software system is developed for the profile and shape measurement of three-dimensional surface using vertical scanning measurement method and zero-order interference fringe tracing method. This software system also includes data pre-processing and parameter evaluation function, and the measurement and evaluation results are provided.更多还原