A Novel Two-Step Alignment Technique for Imprint Lithography
压印光刻中的两步对正技术

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.