通过建立非理想准直光束残余高斯特征的功率密度模型,阐述了光束准直效果与功率密度的关系,借助光束通光比例系数对直写光斑强度分布影响的分析,以光斑主瓣、旁瓣的强度和宽度为主要特征,讨论了直写光斑强度及强度分布与光束准直效果的变化规律,确定了合理选取激光直写系统中准直扩束比例系数的原则。通过仿真不仅系统阐述了理想准直光束与非理想准直光束所形成的直写光斑形状的差异,还描述了理想准直光束近似计算光斑强度分布时的误差形式,这一结论为激光直写机准直系统设计提供了理论依据。

Collimator and extender are the vital segments of beam shaping in laser photolithography. Collimating result influences both the quality of writing spot and writing efficiency directly. In this paper, a mathematic model on power density has been built to describe the residual Gaussian attribute of non-ideal collimated beam. The relation between collimating quality and power density is presented in it. By the analysis on how the limiting aperture proportion factors influence the intensity distribution of laser directing writing spot, the intensity and width of main lobe and side lobe are taken as the major distinction, the varying regularity in different collimated results is discussed on writing spot intensity and its distribution, a principle is confirmed on how to select proper collimator and extender proportion factor. At last, not only the difference between writing spot shaping generated by ideal collimated and non-ideal collimated beam is given by simulation systematically, but also the error form is described, which is caused by ideal collimating approximate calculation. This conclusion provided a theoretic rule for collimator design in laser photolithography.