压印光刻中套刻需要粗、精两级对正．实验采用一对斜纹结构光栅作为对正标记．利用物镜组观察光栅标记图像的边界特征进行粗对正，其准确度在精对正信号的捕捉范围内；利用光电接收器件阵列组合接收光栅莫尔信号，在莫尔信号的线区进行精对正．由于线性区的斜率大，精对正过程中得到相应x，y方向的对正误差信号灵敏度高，利用高灵敏度对正误差信号作为控制系统的驱动信号，对承片台进行驱动定位，实现精对正．最终使X，Y方向上的重复对正准确度分别达到了±21 nm(±3σ)和±24 nm(±3σ)．

A two-step alignment,coarse-fine alignment,is proposed for obtaining high alignment accuracy in room-temperature imprint lithography process. A pair of special slant gratings are used as alignment marks. Coarse alignment was realized by observing the borderlines of the superposed marks through object lens,and alignment accuracy is within the capture range of fine alignment. The Moiré signals in the linear region for fine alignment generated by the alignment marks were detected by a photo-detector array and used to estimate the fine alignment errors in x and y directions respectively. Since the linear region of moiré signal is very steep,the signals highly sensitive to alignment error can be obtained and used to control the alignment of a X-Y stage by fine positioning. The final alignment accuracy can reach ±21 nm in x direction and±24 nm in y direction.