Study of the kinetics of step and flash imprint lithography photopolymerization

Dickey, Michael D.; Burns, Ryan L.; Kim, E. K.; Johnson, Steve; Stacey, Nick; Willson, C. Grant

doi:10.1002/aic.10477

Cited by 38 publications

(47 citation statements)

References 37 publications

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“…Detailed kinetic studies have been carried out to evaluate the impact of oxygen on SFIL. [77,78] Furthermore, the acrylate-based UV imprint resist has a large shrinkage upon curing (ca. 10 %), which may affect the pattern definition or resist adhesion on certain substrates, especially metals and plastics.…”

Section: Uv-curable Liquid Resists For Room-temperature Nanoimprintingmentioning

confidence: 99%

Nanoimprint Lithography: Methods and Material Requirements

2007

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Nanoimprint lithography (NIL) is a nonconventional lithographic technique for high‐throughput patterning of polymer nanostructures at great precision and at low costs. Unlike traditional lithographic approaches, which achieve pattern definition through the use of photons or electrons to modify the chemical and physical properties of the resist, NIL relies on direct mechanical deformation of the resist material and can therefore achieve resolutions beyond the limitations set by light diffraction or beam scattering that are encountered in conventional techniques. This Review covers the basic principles of nanoimprinting, with an emphasis on the requirements on materials for the imprinting mold, surface properties, and resist materials for successful and reliable nanostructure replication.

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Section: Uv-curable Liquid Resists For Room-temperature Nanoimprintingmentioning

confidence: 99%

Nanoimprint Lithography: Methods and Material Requirements

2007

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“…[5,20,27,31,32] Chong et al [21] and Krongauz et al [20] developed early kinetic models that simulated specific effects oxygen had on photopolymerization kinetics. Recently, Dickey et al [33] developed a quasi steady-state approximation kinetic model to study the effect of diffusing oxygen at the etch barrier in Step and Flash Imprint Lithography. However, a comprehensive model including heat and mass transfer effects, and more importantly spatial profiling has never been applied to study the effect of oxygen.…”

Section: Introductionmentioning

confidence: 99%

Modeling the Effect of Oxygen on Photopolymerization Kinetics

O’Brien

Bowman

2006

Macro Theory & Simulations

103

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Summary: A comprehensive one‐dimensional photopolymerization model was utilized to investigate the effect of oxygen on the free‐radical photopolymerization kinetics. The spatial profiling aspect of the model provided insight into the heterogeneity of the cure kinetics due to oxygen inhibition, specifically the variance in the concentration profile of monomer and oxygen. Double bond conversion was negligible for the top ten microns of the film due to continuous oxygen diffusion, and increased with increasing depth. Similarly, the oxygen concentration decreased with increasing depth due to the competition between oxygen diffusion time and the polymerization rate. The effect of initiation rate on the extent of oxygen inhibition was investigated for various oxygen concentrations. As the initiation rate increased, the polymerization rate increased, and eventually approached that of a sample in an inert environment. Similarly, as the oxygen concentration was decreased, the polymerization rate increased. The effect of varying the initiation rate on the cure profile in the oxygen‐exposed film was also studied. It was found that the unpolymerized tacky layer decreased from 50 µm to 5 µm with a 3 order of magnitude increase in initiation rate. Using the pseudo steady state approximation, the relationship between polymerization rate and initiation rate was derived for films in an oxygen environment. A direct relationship between the polymerization and initiation rate was found for films in air. The polymerization model supported this derivation and found that as the oxygen concentration was decreased, the dependence on initiation rate, or alpha, decreased, reaching the accepted value of 0.5 for alpha in inert environments.Double bond conversion versus film depth and cure time.imageDouble bond conversion versus film depth and cure time.

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“…In the case of SL, there is significant interest in developing processes and materials that result in higher throughput, better spatial resolution, and improved surface finishes. Making such improvements would be greatly aided by quantitatively accurate models that can capture the behavior of photopolymer resins during polymerization, and during the last decade several research groups have made significant strides forward [1][2][3][4][5][6][7][8]. One of the main problems with model development is the need for experimental validation and refinement, which is still problematic with existing techniques.…”

Section: Introductionmentioning

confidence: 99%