Negligible impact of UV-curable resist shrinkage on NIL pattern fidelity

Shrinkage of UV-curable resists during nanoimprint lithography (NIL) has long been regarded as a potential source of pattern distortion; however, direct experimental validation of this effect remains scarce. Here, we systematically investigate the influence of resist shrinkage on the imprinted pattern fidelity using two UV-curable resins with distinct volumetric shrinkage ratios (6.8% and 2.6%). Despite this substantial difference, scanning electron microscopy (SEM) reveals no discernible degradation in fidelity of either micro- or nanoscale features across all samples. Notably, certain previously reported distortions may, in fact, originate from electron-beam-induced effects during SEM observation rather than intrinsic material shrinkage. To further quantify macroscopic effects, the profiles of millimeter-scale imprinted lenses were characterized via white-light interferometry. Relative to the mold, the lenses fabricated with resins exhibiting volumetric shrinkage of 6.8% and 2.6% show actual dimensional shrinkage of only 2.5% and 0.36%, respectively. These results indicate that resist shrinkage is largely compensated by the refilling of mold cavities from the residual layer prior to complete curing. Collectively, this work provides compelling experimental evidence that, within the commonly used range, resist shrinkage does not inherently compromise pattern fidelity in NIL.