面对可用焦深日益缩短的趋势，高精度的焦面控制技术显得尤为重要。针对双工件台光刻机中采用的焦面控制技术，介绍了基于偏振调制的光栅检焦技术及其测量原理，研究了双工件台光刻机中的调平调焦技术。基于平面拟合、最小二乘法及坐标变换公式推导了曝光狭缝内离焦量计算公式；研究了一种离焦量解耦算法，该算法将曝光狭缝内离焦量解耦为调平调焦机构三个压电陶瓷的独立控制量，并使狭缝曝光场中心在调平调焦运动过程中不发生平移。经仿真分析表明，该算法可用于调平调焦精度优于10 nm 的高精度调焦调平系统, 能满足线宽小于100 nm 投影步进扫描光刻机的需要。

With the trend of reduction in depth of focus, the control of wafer surface is becoming more and more important. The control of wafer surface in dual-stage lithography is studied. The focus detection method, which is based on the polarization modulation mechanism of dual-grating moiré fringes and its measurement principle, is introduced; then the focusing and leveling technique in dual-stage lithographic system is studied. The algorithm for defocus in exposure slit is evolved by using least square method, surface fitting with a plane and coordinate translation. The defocus-decoupling algorithm is studied in detail, which converts the defocus to movement of the piezoelectric ceramics (PZT) and prevents the shift for the center of the exposure slit. The algorithm can be used for precision of 10 nm in focusing and leveling by the simulation, which can meet the need of projection step scan lithography machine with line width less than 100 nm.