Molecular dynamics simulation of mechanical strengthening properties of SiC substrate covered with multilayer graphene

Abstract

A large number of practices have shown that under the coupling influence of complex working conditions and frequent reciprocating contact, the surfaces of semiconductor devices in micro/nano electromechanical systems often produce adhesive wear, which is the essential reason resulting in short durability service life and declining contact mechanical properties for microelectronics semiconductor devices. However, graphene can significantly improve the interface properties of mechanical components and electronic components due to its excellent mechanical properties, such as high carrier concentration, good thermal conductivity, and low shear. Thus, the study of mechanical strengthening properties and plastic deformation of SiC material with covered multi-layer graphene in MEMS devices will play a significant role in improving the durability service life of MEMS device, and understanding its strengthening and toughening mechanism. Therefore, this paper studies and discusses the effects of stacking type and extreme service temperature with low and high levels on the contact mechanical properties (maximum load, hardness, Young modulus, contact stiffness), micro-structure evolution, contact mass, fold morphology, and total length of dislocation. The atomic-scale mechanism of enhanced mechanical properties of SiC material with multi-layer graphene is explained. The research shows that the damage to carbon-carbon bond at the maximum indentation depth will lead graphene to lose the excellent in-plane elastic deformation capability when the graphene stacking type is AB stacking, so that the maximum load-bearing capacity of the substrate covered by three layers of graphene will drop linearly. In addition, the mechanical property of SiC material coated with three graphene layers is twice that of pure SiC substrate, and the strengthening mechanism is mainly due to the increase of wrinkle caused by the increase of multilayer graphene loading, which causes the quality of contact between the SiC substrate and the virtual indenter to decrease, thus increasing the interface contact stiffness. The increase of the active temperature will trigger off the increase of the atomic vibration frequency, which will cause the number of interface contact atoms to increase greatly, and the interface contact stiffness will weaken, and finally lead the interface contact quality to improve, This is because the mechanical properties of SiC substrate coated with multilayer graphene will decrease approximately linearly with the extreme service from low temperature to high temperature. In addition, the stress concentration in the subsurface layer of SiC substrate can induce the evolution of its micro-structure, and the increase of the number of graphene layers on the substrate can effectively reduce the stress concentration distribution in the subsurface layer of the substrate.