Impact of the resist properties on the antisticking layer degradation in UV nanoimprint lithography
Conversion rate for the three pure monomeric resists studied (TEGDA, TEGDMA, and PEGMA) as a function of the UV exposure time.
Electron spin resonance spectra for the three resist studied [(a) PEGMA, (b) TEGDMA, and (c) TEGDA] containing micrometric untreated silica beads after 1 s UV irradiation (black) and of resist containing micrometric Optool DSX treated silica beads after 1 s UV irradiation (gray).
AFM image of an indented surface of cured TEGDMA (20s exposure, 77% conversion ratio) using a Berkovich tip. The scan dimension is , and the maximum load force was 0.15 nN.
Typical load-displacement curves during the nanoindentation experiments for the three resists used [TEGDA (100 s exposure, 79% conversion ratio), TEGDMA (150 s exposure, 65% conversion ratio), and PEGMA (100 s exposure, 50% conversion ratio)].
Surface energy of an Optool DSX treated fused silica mold as a function of the number of imprints in two different resists [(a) TEGDA and (b) TEGDMA] and for different exposure times per imprint.
Surface energy of an Optool DSX treated fused silica mold as a function of the number of imprints for the three resist used and for a practical exposure time in the UV nanoimprint process for each resist: TEGDA (1 s exposure, 62% conversion ratio), TEGDMA (10 s exposure, 75% conversion ratio), and PEGMA (50 s exposure, 48% conversion ratio).
Chemical formulae and physical properties of the chosen acrylate-based monomers for the formulation of the studied resists.
ESR signal decreases ratio when an antisticking layer treatment is used for the three resists studied.
Mechanical properties (elastic modulus and hardness) of the studied resists obtained by nanoindentation for several degrees of photopolymerization. *Values below 1 GPa has to be considered with care since they are below the usually accepted validity range of the Oliver and Pharr method.
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