The thermal imprint process of polymer micro-patterning is widely applied in areas such as manufacturing of optical parts, solar energy, bio-mechanical devices and chemical chips. Polycarbonate (PC), as an amorphous polymer, is often used in thermoforming processes because of its good replication characteristics. In order to obtain replicas of the best quality, the imprint parameters (e.g., pressure, temperature, time, etc.) must be determined. Therefore finite element model of the hot imprint process of lamellar periodical microstructure into PC has been created using COMSOL Multiphysics. The mathematical model of the hot imprint process includes three steps: heating, imprinting and demolding. The material properties of amorphous PC strongly depend on the imprint temperature and loading pressure. Polycarbonate was modelled as an elasto-plastic material, since it was analyzed below the glass transition temperature. The hot imprint model was solved using the heat transfer and the solid stress-strain application modes with thermal contact problem between the mold and polycarbonate. It was used for the evaluation of temperature and stress distributions in the polycarbonate during the hot imprint process. The quality of the replica, by means of lands filling ratio, was determined as well.
References
[1]
Mínguez-Vega, G.; Tajahuerce, E.; Fernández-Alonso, M.; Climent, V.; Lancis, J.; Caraquitena, J.; Andrés, P. Dispersion-compensated beam-splitting of femtosecond light pulses: Wave optics analysis. Opt. Express 2007, 15, 278–288.
[2]
Liu, J.; Thomson, M.; Waddie, A.J.; Taghizadeh, M.R. Design of diffractive optical elements for high-power laser applications. Opt. Eng. 2004, 43, 2541–2548.
[3]
Emiliani, V.; Cojoc, D.; Ferrari, E.; Garbin, V.; Durieux, C.; Coppey-Moisan, M.; Di Fabrizio, E. Wave front engineering for microscopy of living cells. Opt. Express 2005, 13, 1395–1405.
Yang, X.L.; Cai, L.Z.; Wang, Y.R.; Liu, Q. Interference of four umbrellalike beams by a diffractive beam splitter for fabrication of two-dimensional square and trigonal lattices. Opt. Lett. 2003, 28, 453–455.
[6]
Ferraro, P.; Grilli, S.; Alfieri, D.; de Nicola, S.; Finizio, A.; Pierattini, G.; Javidi, B.; Coppola, G.; Striano, V. Extended focused image in microscopy by digital holography. Opt. Express 2005, 13, 6738–6750.
[7]
Mann, C.J.; Yu, L.; Kim, M.K. Movies of cellular and sub-cellular motion by digital holographic microscopy. Biomed. Eng. Online 2006, 23, 5–21.
[8]
Satake, S.; Kanamori, H.; Kunugi, T.; Sato, K.; Ito, T.; Yamamoto, K. Parallel computing of a digital hologram and particle searching for microdigital-holographic particle-tracking velocimetry. Appl. Opt. 2007, 46, 538–550.
[9]
Charrière, F.; Kühn, J.; Colomb, T.; Montfort, F.; Cuche, E.; Emery, Y.; Weible, K.; Marquet, P.; Depeursinge, C. Characterization of microlenses by digital holographic microscopy. Appl. Opt. 2006, 45, 829–837.
[10]
Horimai, H.; Tan, X. Collinear technology for a holographic versatile disk. Appl. Opt. 2006, 45, 910–922.
[11]
Abd Rahman, S.F.; Hashim, U.; Nor, M.N.M.; Shohini, M.E.A. Fabrication of nano and micrometer structures using electron beam and optical mixed lithography process. Int. J. Nanoelectron. Mater. 2011, 4, 49–58.
[12]
Heckele, M.; Schomburg, W.K. Review on micro molding of thermoplastic polymers. J. Micromech. Microeng. 2004, 14, 1–14.
[13]
Worgull, M.; Hétu, J.F.; Kabanemi, K.K.; Heckele, M. Modeling and optimization of the hot embossing process for micro- and nanocomponent fabrication. Microsyst. Technol. 2006, 12, 947–952.
[14]
Liu, C.; Li, J.M.; Liu, J.S.; Wang, L.D. Deformation behavior of solid polymer during hot embossing process. Microelectron. Eng. 2010, 87, 200–207.
[15]
Mekaru, H.; Goto, H.; Takahashi, M. Development of ultrasonic micro hot embossing technology. Microelectron. Eng. 2007, 84, 1282–1287.
[16]
Hirai, Y.; Yoshida, S.; Takagi, N. Defect analysis in thermal nanoimprint lithography. J. Vac. Sci. Technol. B 2003, 21, 2765–2770.
[17]
Narijauskaite, B.; Palevicius, A.; Narmontas, P.; Ragulskis, M.; Janusas, G. High-frequency excitation for thermal imprint of microstructures into a polymer. Exp. Tech. 2011, doi:10.1111/j.1747-1567.2011.00724.x.
[18]
Seunarine, K.; Gadegaard, N.; Riehle, M.O.; Wilkinson, C.D.W. Optical heating for short hot embossing cycle times. Microelectron. Eng. 2006, 83, 59–863.
[19]
Pennec, F.; Achkar, H.; Peyrou, D.; Plana, R.; Pons, P.; Courtade, F. Verification of Contact Modeling with COMSOL Multiphysics Software. Proceedings of the Federation of European Simulation Societies Conference (EUROSIM), Ljubljana, Slovenia, 9–13 September 2007.
[20]
Wriggers, P. Computational Contact Mechanics; Springer: Berlin, Germany, 2006; p. 518.
Goel, A.K. Thermodynamically Consistent Large Deformation Constitutive Model for Glassy Polymers. Ph.D. Thesis, University of Nebraska, Lincoln, USA, December 2009.
[23]
Engels, T.A.P.; Govaert, L.E.; Meijer, H.E.H. The influence of molecular orientation on the yield and post-yield response of injection-molded polycarbonate. Macromol. Mater. Eng. 2009, 294, 821–828.
