A method for in situ measurement of residual layer thickness in nano-imprint lithography

•We proposed an innovative application of surface palsmon resonance (SPR) in nano-imprint lithography (NIL) for the thickness of residual layer.•A novel mold is fabricated successfully by the proposed fabrication process.•A monitoring system is developed for measuring the reflectivity spectrum.•Both experiment and simulation results demonstrate the effectiveness of this method in monitoring the thickness of residual layers.

Nanoimprint lithography has the advantages of high throughput, sub-10-nm fabrication process, and low cost. However, residual layer encountered in the imprinting process requires removal through reactive ion etching to maintain pattern fidelity. This study proposes a non-destructive method in situ to measure the thickness of residual layer, employing surface plasmon resonance in the imprinted feature during the imprinting stage. Variations in the thickness of the residual layer change the resonance patterns, including the reflectivity and resonance angle. Both experiment and simulation results demonstrate the effectiveness of this method in monitoring the thickness of residual layers.

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