Master-based distortion correction method for wafer-scale nanoimprint lithography

Abstract

Nanoimprint lithography (NIL) is a versatile and cost-effective technology enabling patterning for applications in optics, photonics and semiconductor manufacturing. Although Soft UV-NIL process enables wafer scale replication, achieving optimal overlay (OVL) accuracy remains challenging, particularly due to distortion, which is the primary contributor of global OVL errors, ahead of translation and rotation. Following process stabilization, the distortion signature was found to be systematic and repeatable. To address these challenges, the study presents the Distortion Corrected Master (DCM) method based on master pre-correction through e-beam lithography. This study utilizes e-beam lithography Vistec SB3054 with advanced metrology, enabling precise measurement of global distortion on 200 mm wafers. The test vehicle used is a Vistec Distortion Metrology Master (DMM), containing 4,825 uniformly distributed measurement marks across the entire wafer surface. The inverse distortion mapping is then computationally derived and incorporated into the e-beam writing parameters for fabricating a corrected master with an identical layout. Following DCM replication, a second measurement is performed to quantify imprinted wafer global distortion. Through this iterative methodology, we successfully demonstrate the ability to achieve a maximum post-replication distortion of 380 nm in X and 460 nm in Y. Furthermore, the distortion signature acquired with the DMM was successfully transferred to a functional master, suggesting the method’s transferability across designs. An initial repeatability assessment suggests process stability across multiple wafer batches. These results meet industrial optical lithography standards, and suggest that DCM could become a standard approach for distortion correction.