A novel detection method used to avoid the effect of mould damage on the performance of surface plasmon resonance measurement for measuring the residual layer thickness in nano-imprint lithography

Abstract

Surface plasmon resonance (SPR) is a powerful method for measuring biomolecular interactions, refractive indices and the thickness of nano–scale films. Recent studies have proposed novel SPR applications for measuring the thickness of residual layers in nano–imprint lithography (NIL). Although numerical simulation and experimental studies have confirmed the accuracy and reproducibility of NIL measurements, no study has been conducted on the effect of mould damage on detection accuracy. In this study, the influence of mould damage on measuring the thickness of residual layers is analysed. The results reveal that the effect of mould damage on the reflectivity spectrum for measuring residual layers is not obvious. Thus mould damage is easy to be ignored. To address the problem, this paper proposes measuring the SPR spectrum before the imprint process for detecting mould damage. The results demonstrate that resolution of the measurements has the potential to be better than 5 nm. This paper elucidates the effect of mould damage on the accuracy of measuring residual layer and improves the performance of NIL–based SPR measurement.