Automatic High Precision Alignment Technique
Using Moiré Signals for Imprint Lithography
Wang Yanrong,Cui Dongyin, Ding Yucheng,Wang Li
(State Key Laboratory for Manufacturing Systems Engineering,Xi'an Jiaotong
University,Xi'an 710049, China)
Abstract:A pair of diagonal gratings is utilized to improve automatic alignment
precision for imprint lithography.Gratings are divided into four areas with different
pitch and angle,Moiré signals from the four areas of grating pair can be detected
by an array of photoelectric detector, and all signals from detector are amplified and
evaluated by simulative circuitry according to their logic relation,and the average value
of circuit outputs as misalignment signals in x-y-θdirections can be used to control the
positioning system.Motors and piezoelectric translators (PZT) are used to actuate in two
grades (coarse and fine) of motion to meet the alignment requirements,and laser
interferometers to monitor the process of alignment. It indicates that the accuracy of 10
nm step of imprint stage can be reached,and the alignment uncertainty of the whole
alignment system is less than 30 nm in multi-layer imprint lithography process.
Keywords:imprint lithography;grating;automatic alignment;actuator