一种新型投影曝光调焦方法

A new zooming method for projection imaging lithography

为研究大面积激光投影光刻的调焦,利用Zemax光学设计软件模拟离焦对光程差(OPD)和调制传递函数(MTF)的影响,分析二者对投影曝光图形质量的影响,给出系统最大的离焦量值。提出一种利用显微镜的调焦方法,分析此方法的调焦误差主要来自于显微镜景深,根据景深表达式和系统最大离焦量值,选择一款景深不大于系统最大离焦量的显微镜来构建调焦系统,并基于该调焦系统进行光刻实验。实验结果表明:利用该方法对投影成像光刻进行调焦,无论是否离焦,边缘视场与中心视场的MTF均有差异,分辨率也有差异,但这种差异不影响光刻图形的质量。

In order to study the zooming for large-area laser projection lithography, using Zemax optical design software, the defocusing effect on modulation transfer function （MTF） and opti- cal path difference （OPD） was simulated, the effect of OPD and MTF on the imaging quality of projection imaging lithography was analyzed, and the maximum defocusing range of the system was also provided. A zooming method by using microscope was proposed, the zooming errors of this method was mainly come from the depth of field of microscope. According to the ex- pression of the depth of field and the maximum defocusing value of this system, a microscope whose depth of field was not more than the maximum defocusing amount was chosen to con- struct the zooming system. The experiment was demonstrated based on the zooming system for lithography. Experiment results illustrate that the new zooming method for project imaging li- thography can obtain a good lithography image quality.