Consecutive imprinting performance of large area UV nanoimprint lithography using Bi-layer soft stamps in ambient atmosphere

- A center-to-edge imprinting scheme using bi-layer polymer soft stamp is presented.
- Stamp characterization by nanoindentation tests.
- Reusability of a single soft stamp in ambient atmosphere for twenty consecutive imprints.
- Imprinting uniformity using a single soft stamp in ambient atmosphere for twenty consecutive imprints.

For UV nanoimprint lithography (UV-NIL) using polymer soft stamps, imprinting at ambient atmosphere brings additional challenges due to evaporated solvents and possible byproducts resulting from the interaction between the UV light, oxygen and the polymer-based material. Moreover, the Laplace pressure may impact differently on the capillary filling for both positive and negative patterns at atmospheric pressure compared to that in the vacuum. Twenty consecutive imprints using bi-layer Polydimethylsiloxane (PDMS), PDMS/toluene-diluted PDMS, PDMS/X-PDMS, PDMS/vvsPDMS stamps have been tracked and inspected. The imprinting employs a center-to-edge scheme in ambient atmosphere. The results show that high reusability and imprint uniformity can be achieved for at least twenty consecutive imprints using the pure PDMS (PDMS/PDMS) and PDMS/toluene-diluted PDMS. These stamps can overcome the challenges of the interaction between the UV light, oxygen and the polymer-based materials. The Laplace pressure under atmosphere does not hinder the resist filling for such consecutive imprints.

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