PROPERTY SIMULATION FOR NANO-SCALE INTERFACIAL FRICTION BETWEEN TWO KINDS OF MATERIAL IN MEMS BASED ON AN ATOMISTIC SIMPLIFIED MODEL

The objective of this research work is to provide a systematic method to perform molecular dynamics simulation or evaluation for nano-scale interfacial friction between different materials in MEMS. A simplified model to simulate surface sliding between different kinds of material by molecular dynamics [MD] is proposed because the surface property is a dominant factor for the performance between two kinds of material in MEMS. The Newton's equations of motion are established by using the Morse potential function. An improved Verlet algorithm is employed to solve atom trajectories. Comparing the results of the computer simulation with experimental results in Ref. 1, the validity of the model is confirmed. The simulation results show that the preliminary stage and the last stage, when no interface is formed, the friction force fluctuates periodly and its peak value is smaller relatively, while at the intermediate stage, where the interface is formed, the friction force fluctuates periodly and its peak value is relatively bigger. The friction force is approximately proportional to the contact area. In the meantime, Cu sliding along Al with uniform speed and accelerated motion was also investigated, the mechanical properties between two surfaces were analyzed and a tentative computational simulation on the effect of the driving force was developed. The results lay a basis for future work.