Choice of the molecular weight of an imprint polymer for hot embossing lithography

Schulz, H.; Wissen, M.; Bogdanski, N.; Scheer, Hella-Christin; Mattes, K.; Friedrich, Chr.

doi:10.1016/j.mee.2004.12.079

Cited by 35 publications

(42 citation statements)

References 6 publications

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“…The maximum value reached for the ratio of the initial height is found to be 35.1/ 29.6= 1.18. This value was reached after an annealing 25,27] data from [25] data from [2,25] data from [26,27] Ln[η/ηs(T=150°C)]…”

Section: Resultsmentioning

confidence: 99%

Thin polymer films viscosity measurements from nanopatterning method

Leveder

Landis

Chaix

et al. 2010

Journal of Vacuum Science &Amp; Technology B, Nanotechnology and Microelectronics: Materials, Processing, Measurement, and Phen

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Polystyrene films, with thickness ranging from a few tens of nanometers up to several hundreds of nanometers and molecular weight of 27.5 kg mol−1, were patterned with nanoimprint lithography (NIL) technique. A rigid silicon stamp containing nanoscale features was printed into a thin spin coated polystyrene film. Then these patterns were annealed above the glass transition temperature in order to characterize the viscous reflow of the topography. Special attention was paid to provide, at initial times, imprinted nanoscale patterns with a very small aspect ratio and amplitude/wavelength as well as to avoid the nucleation of holes during imprinting or during the course of the reflow. This allowed the authors to process topography data with a high degree of accuracy from a linear viscous stability model. Atomic force microscopy measurements, with a spatial resolution lower than 1 nm, were used to characterize smooth or steep shapes. The mechanical measurements of earlier stages of pattern reflow were directly accessible without any assumption, contrary to the diffraction method usually employed. Our results clearly demonstrate that even the earliest stages of pattern reflow are driven by simple viscous effects and that relaxation dynamics, which is usually considered as following exponential laws, could be more complex. This article also demonstrates that the NIL process can be used for viscosity measurements for ultrathin resist film.

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Section: Resultsmentioning

confidence: 99%

Thin polymer films viscosity measurements from nanopatterning method

Leveder

Landis

Chaix

et al. 2010

Journal of Vacuum Science &Amp; Technology B, Nanotechnology and Microelectronics: Materials, Processing, Measurement, and Phen

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“…In comparison to PS18.7k, the PS96.9k is more susceptible to the shear thinning, which is normal behavior for higher molar mass polymers. [31,32] For PS1510k, the t KWW increases only moderately with the imprinting temperature. As T imp increases from T g þ 20 8C to T g þ 80 8C, the average relaxation time, t KWW increases from approximately 18 min to 87 min for the 430 nm pitch pattern and 34 min to 61 min for the 850 nm pitch pattern.…”

Section: Nil Processmentioning

confidence: 98%

Nanoimprint Lithography and the Role of Viscoelasticity in the Generation of Residual Stress in Model Polystyrene Patterns

Ding

Alvine

et al. 2008

Adv Funct Materials

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Understanding polymer deformation during the nanoimprinting process is key to achieving robust polymer nanostructures. Information regarding this process can be extracted from monitoring the decay of the imprinted polymer patterns during thermal annealing. In the present work, the effect of both the molar mass and the imprinting temperature on the pattern decay behavior during thermal annealing is investigated. Previously, it was found that the decay rate is fastest for a highly entangled polymer due to the elastic recovery caused by the residual stress created during the imprinting process. The present paper demonstrates that this residual stress level can be modified through control of the imprinting temperature. These results are contrasted with those for an unentangled polymer over a similar range of imprinting temperatures, where it is found that the pattern decay is controlled by simple Newtonian flow. In particular, the pattern decay is well described by surface‐tension‐driven viscous flow, and no imprinting‐temperature effect is observed during thermal annealing. It is shown that the stability of the film against pattern decay can be optimized for moderately entangled polymer films. This effect is attributed to the competition between the effect of increased viscosity with increasing molar mass and increased residual stresses with entanglements. These observations provide guidance for the optimization of imprinting process in terms of selection of molar mass and processing temperatures.

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“…This fits well with the requirements for the imprint of PS. Earlier rheological characterization measurements 8 show that a substantial viscosity reduction results even at a frequency of only 10 Hz: at 170 C, a typical imprint temperature for the polymer used, a viscosity of about 10 4 Pa s is obtained at 10 Hz-about one-tenth of the zero shear value (no frequency) at that temperature. If the frequency is kept constant and the temperature is lowered, the zero shear value will increase, but the viscosity at 10 Hz will remain almost constant, resulting in a high viscosity reduction compared to the zero shear value.…”

Section: Methodsmentioning

confidence: 91%

“…We use piezo translators for dynamic agitation in the lower frequency range. First experiments with polystyrene (PS) as an imprint material, for which a full rheological characterization is at hand, 8 indicate a substantial improvement of the imprint depth under dynamic agitation at a temperature as low as 100 C, around the glass temperature T g of the imprint material. As a basis for performing controlled imprint experiments under dynamic excitation, the piezo-based imprint system was characterized with respect to its frequency behavior and its mechanical behavior.…”

Section: Introductionmentioning

confidence: 99%