| 1. | Grzywacz H., Jenczyk P., Milczarek M., Michałowski M.♦, Jarząbek D.M., Burger model as the best option for modeling of viscoelastic behavior of resists for nanoimprint lithography, Materials, ISSN: 1996-1944, DOI: 10.3390/ma14216639, Vol.14, No.21, pp.6639-1-12, 2021 Abstract:In this study, Atomic Force Microscopy-based nanoindentation (AFM-NI) with diamond-like carbon (DLC) coated tip was used to analyze the mechanical response of poly(methyl methacrylate) (PMMA) thin films (thicknesses: 235 and 513 nm) on a silicon substrate. Then, Oliver and Pharr (OP) model was used to calculate hardness and Young’s modulus, while three different Static Linear Solid models were used to fit the creep curve and measure creep compliance, Young’s modulus, and viscosity. Values were compared with each other, and the best-suited method was suggested. The impact of four temperatures below the glass transition temperature and varied indentation depth on the mechanical properties has been analyzed. The results show high sensitivity on experiment parameters and there is a clear difference between thin and thick film. According to the requirements in the nanoimprint lithography (NIL), the ratio of hardness at demolding temperature to viscosity at molding temperature was introduced as a simple parameter for prediction of resist suitability for NIL. Finally, thinner PMMA film was tentatively attributed as more suitable for NIL. Keywords:PMMA, atomic force microscopy-based nanoindentation, Young’s modulus, hardness, viscosity, Burger creep model, nanoimprint lithography Affiliations:| Grzywacz H. | - | IPPT PAN | | Jenczyk P. | - | IPPT PAN | | Milczarek M. | - | IPPT PAN | | Michałowski M. | - | Warsaw University of Technology (PL) | | Jarząbek D.M. | - | IPPT PAN |
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| 2. | Grzywacz H.♦, Milczarek M., Jenczyk P., Dera W., Michałowski M.♦, Jarząbek D.M.♦, Quantitative measurement of nanofriction between PMMA thin films and various AFM probes, MEASUREMENT, ISSN: 0263-2241, DOI: 10.1016/j.measurement.2020.108267, Vol.168, pp.108267-1-13, 2020Abstract:This study reports the quantitative, precise and accurate results of nanoscale friction measurements with the use of an Atomic Force Microscope calibrated with a precise nanoforce sensor. For this purpose, three samples of spin-coated thin Polymethylmethacrylate (PMMA) films were prepared with the following thicknesses: 235, 343, and 513 nm. Three different AFM probes were used for the friction measurements: with diamond-like carbon (DLC) tip with a small (15 nm) or big (2 µm) tip radius, and a reference silicon tip with a small (8 nm) radius. The results show that in all of the studied cases, the coefficient of friction strongly depends on the applied load, being much higher for a lower load. Furthermore, a strong relation of the friction force on the cantilever's geometry, the scanning velocity, and the film thickness was observed. Keywords:lateral force microscopy, friction, thin PMMA films, atomic force microscope, DLC coatings, adhesion Affiliations:| Grzywacz H. | - | other affiliation | | Milczarek M. | - | IPPT PAN | | Jenczyk P. | - | IPPT PAN | | Dera W. | - | IPPT PAN | | Michałowski M. | - | Warsaw University of Technology (PL) | | Jarząbek D.M. | - | other affiliation |
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