TED-AJ03-427 MODELING AND SIMULATION OF THERMOMECHANICAL NANO-INDENTATION IN POLYMER

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概要

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• In thermomechanical data storage, a heated atomic force microscope cantilever is in contact with and scans over a thin polymer film. Thermal reading is possible through measurement of the electrical resistance signal of the cantilever, which is a function of the cantilever-substrate thermal conductance. Figure A-1 shows thermomechanical data writing and thermal data reading. Two main figures of merit for this technology are the time required for data bit formation and the size of the data bit formed, both which depend upon heat transfer in the cantilever tip and heat and mass transfer in the polymer layer. This paper describes modeling and simulation of heat and mass transfer during data bit formation. Detailed modeling of heat and mass transfer in the cantilever tip and the polymer layer is required for accurate prediction of bit writing conditions. The silicon cantilever tip is 300-500 nm in height and has a radius of curvature of 20 nm. The average mean free path of the heat-carrying acoustic phonons in pure, bulk silicon is 300 nm at room temperature and thus phonon-boundary scattering affects thermal conduction in the tip. The polymer film is of thickness comparable to or less than the radius of gyration of the unperturbed polymer molecule, and thus its glass transition temperature and thermophysical properties are likely different from bulk values. Experimental uncertainties associated with the extremely small length and time scales of indentation prevent experimental results from fully informing the indentation formation process. Thus, A modeling approach that accounts for sub-continuum conduction in the cantilever tip and for the time- and temperature-dependant mechanical properties of the polymer predicts the threshold conditions required for bit formation. An exact solution for the tip-polymer contact size and shape provides a relation between the tip shape, loading force, and polymer properties. Solution of the transient conduction equation in the polymer layer provides the temperature distribution in the polymer layer. Time-temperature superposition, coupled with time- and temperature-dependant bulk properties, predicts the polymer viscoelastic properties. Simulations predict near steady-state and transient indentation formation, and yield results that compare well with data. For loading forces of between 10 nN and 200 nN and a tip radius of 20 nm, a cantilever temperature of 200℃ is required to form an indentation at near steady-state. For heating pulses as short as 5 μs, the cantilever temperature required for bit formation is as high as 500℃. By quantifying the conditions required for indentation formation, this work enables the design of data storage cantilevers for thermomechanical data writing. The heated cantilever tip could also be used as a tool for nanoscale thermal processing, and advanced manufacturing.[figure]

• 一般社団法人日本機械学会の論文

著者

• King William

  Woodruff School Of Mechanical Engineering Georgia Institute Of Technology

• Goodson Kenneth

  Department of Mechanical Engineering Stanford University

関連論文

• TED-AJ03-427 MODELING AND SIMULATION OF THERMOMECHANICAL NANO-INDENTATION IN POLYMER
• Size Effect on Thermal Conduction in Silicon-on-Insulator Devices under Electrostatic Discharge (ESD) Conditions
• Effect of Resistance Drift on the Activation Energy for Crystallization in Phase Change Memory

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