调焦调平测量系统(FLMS),实时测量硅片曝光视场区域与投影物镜焦面的相对位姿,其测量准确度影响光刻机曝光成像质量。调焦调平测量采用大入射角将3个以上的探测光斑投影到硅片曝光视场区域实现对硅片高度和倾斜的测量。如果光斑位置存在误差,就会引起硅片测量准确度误差,进而造成硅片曝光视场区域离焦,影响曝光成像质量。根据调焦调平单点几何测量模型,建立了光斑位置误差模型。研究结果表明,调焦调平单光斑的测量高度误差与光斑水平位置误差成正比,经调整调焦调平的零平面与焦面近似平行,并精确校准光斑水平位置误差到0.05 mm,其造成的测量误差最大为10 nm。

Focusing and leveling measurement system(FLMS),as a key subsystem of the scanner,is used to detects height and tilts between wafer exposure area and the projection lens in real time. Its performance greatly affects the image quality of projection lens. Based on the grazing-incident beam method ,FLMS detects height and tilts by using more than 3 probe spots on wafer exposure area. Spot position errors cause measurement errors and defocus of exposure area which affect the image quality. Based on the one-spot measurement model,position error model of probe spot is presented. It is found that the height measurement error is proportional to the spot position error,and the accuracy caused by spot position error is less than 10 nm when the zero plane of FLMS is well adjusted,and spot position error is 0.05 mm.