Ultra-precision alignment for room-temperature multi-layer imprint lithography

An ultra-precision alignment technique adopting a pair of special slant gratings was presented for room-temperature imprint lithography. The 0th-order beams of moire signals generated by the gratings were received by a photoelectric detector array, and then the misalignment errors in X-Y directions were obtained, respectively. The contrast of moire signals was improved via adjusting the grating gaps, thus the improved signals were chosen to control the alignment of a X-Y stage by means of coarse-fine positioning system. The laser interferometers were considered as the feedback elements of the control system to monitor the process. Finally, the repeatable alignment accuracy (± 20 nm) ensures to meet the requirement of alignment accuracy for sub-100 nm imprint lithography.