【摘要】 提出一种外差干涉与共焦显微技术融合用于微电子掩膜板台阶高度测量的方法,同时实现了高分辨率(亚纳米)与较大量程(5μm以上)测量,构成了双频干涉共焦显微系统DICM。实验比较了3组物镜数值孔径NA、放大倍数β条件下的共焦显微系统轴向响应曲线,证实了纯共焦方法在轴向分辨率提高方面的局限性,但其光强变化足以区分干涉条纹的级次。将该系统应用于微电子掩模板台阶高度标准的测量,实验表明DICM的测量值与国际比对结果相符合,系统具有良好的复现性,极限偏差小于5nm。更多还原

【Abstract】 A novel method combining heterodyne interferometry with confocal microscopy is proposed to measure the step height of the microelectronic mask. By means of this method, a system of Dual-frequency Interferometric Confocal Microscope (DICM) is developed that implements high resolution (sub-nanometer) and relatively large measurement range (over 5 μm) simultaneously. Three axial response curves of confocal microscopy system are respectively given and compared by the experiments using varied microscopic objects with different numerical aperture(NA) and magnified multiples(β). The results testify the limitation of improving the axial resolution of traditional confocal microscopy, however, the variation of light intensity is enough to discriminate different orders of interference fringes. DICM has been successfully utilized to measure the mask standard step height and the experimental results agree well with that of the international calibration. The results also show the system has good repeatability with a maximum deviation of 5 nm.更多还原