提出一种精确检测光刻机激光干涉仪测量系统非正交性的新方法。将对准标记曝光到硅片表面并进行显影;利用光学对准系统测量曝光到硅片上的对准标记理论曝光位置与实际读取位置的偏差;由推导的位置偏差与非正交因子、坐标轴尺度比例、过程引入误差的线性模型,根据最小二乘原理计算出干涉仪测量系统的非正交性。实验结果表明,利用该方法使用同一硅片在不同旋转角下进行测量,干涉仪测量系统非正交因子的测量重复精度优于0.01 μrad,坐标轴尺度比例的测量重复精度优于0.7×10-6。使用不同的硅片进行测量,非正交因子的测量再现性优于0.012 μrad,坐标轴尺度比例的测量再现性优于0.6×10-6。

A novel method for measuring the non-orthogonality of the interferometer system in a step and scan lithographic tool is presented. First a linear module among the non-orthogonal factor, scaling factor and process related system error has been developed. By real lithographic process the alignment marks are transferred to the wafer, and after development the positions of marks are read out by optic alignment system in the same lithographic tool. The measurement data are used to calculate the non-orthogonal factor and scaling factor of the interferometer by the linear model according to the least square principle. Experimental results show that by this method with the same wafer in different rotation, the measurement repeatability of the non-orthogonal factor is better than 0.01 μrad, and the measurement repeatability of the y to x scaling factor is better than 0.7×10-6. With different wafer in the same condition, the measurement reproducibility of the non-orthogonal factor is better than 0.012 μrad, and the measurement reproducibility of the y to x scaling factor is better than 0.6×10-6.