Chemomechanics of transfer printing of thin films in a liquid environment
Y Zhang and BOO Kim and Y Gao and DS Wie and CH Lee and BX Xu, INTERNATIONAL JOURNAL OF SOLIDS AND STRUCTURES, 180, 30-44 (2019).
The liquid-assisted transfer printing is emerging as a competitive manufacturing technique in the delivery and-assembly of thin film- layered functional materials and-structures. In essence: this technique is underpinned by the detachment of thin films under a synergistic effect of external mechanical loading and interior chemical reaction at interfaces in a liquid environment. Here, we have developed a comprehensive chemomechanics theory for the transfer printing of thin films from as-fabricated SiO2/Si wafer substrate in a liquid water environment. The kinetic chemical reaction at the interface of liquid molecules and interfacial solid bonds is incorporated into the interface energy release rate of thin film detachment, and a rate dependent interfacial debonding process is obtained. We further couple it with mechanical deformation of thin films by taking into account various peeling conditions including peeling rate, peeling angle and thin film thickness to theoretically predicate the steady-state peeling force. Besides, we implement this chemomechanics theory into a finite element model with all atomic information informed and present a reactive atomistic-continuum multiscale model to simulate the detachment of thin films at the continuum scale. In parallel, we have conducted the peeling experiments of three different separation layers on wafer substrates in both dry air and water conditions. Quantitative comparisons among theoretical predictions, simulation results, and experimental measurements are performed and good agreement is obtained. The competition between interfacial delamination and mechanical deformation of thin films during peeling is also analyzed, and a theoretical phase diagram is given to provide an immediate guidance for transfer printing of silicon nanomembranes in the fabrication of functional structures and electronic devices. In addition, the capillary force due to surface wettability of materials is discussed and compared with chemical reaction-induced driving force for transfer printing on a wide range of thin film/substrate systems. The chemomechanics theory and reactive atomistic-continuum simulation model established are expected to lay a foundation for quantitative understanding and descriptions of transfer printing of thin films in a liquid environment. (C) 2019 Published by Elsevier Ltd.
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