点衍射干涉仪小孔掩模技术研究进展

Research Progress of Pinhole Mask Technology of Point Diffraction Interferometer

在点衍射干涉仪中小孔掩模的主要作用是通过衍射产生接近理想的球面波用于干涉测量,其直径、圆度及三维形貌对测量精度有决定性影响。介绍了小孔掩模的结构与作用原理,对小孔衍射电磁场仿真技术进行了分类比较。对国内外现有小孔掩模加工技术的发展进行了归纳总结,阐述了聚焦离子束刻蚀、电子束曝光等加工技术的加工原理、加工精度及技术特点,指出了掩模对准精度对测量重复性的影响。分析了各种检测方法及存在的主要技术问题,并对小孔三维形貌的测量技术进行了展望。

The main role of the pinhole mask of point diffraction interferometer is to produce a nearly ideal spherical wave for interferometry through diffraction. The quality of the reference wavefront depends on the pinhole diameter, roundness and three-dimensional surface profile. The structure and principle of pinholes are introduced, and the classification and comparison of the pinhole diffraction electromagnetic field simulation technology are made. The pinhole mask processing technologies are summarized, and the machining mechanism, precision and technical features of focused-ion-beam etching and electron-beam lithography are expounded. The influence of mask alignment accuracy on measurement repeatability is pointed out. The different testing approaches and the main technical problems are analyzed and the trend of the pinhole three-dimensional topographical measurement technology is described.