Comparison of Indentation and Scribing Behaviors of Crystalline and Initially Deformed Silicon Tips by Molecular Dynamics Simulation

Abstract

Silicon probe tips are used widely in micro and nano-systems such as AFM, MEMS, and probe recording. The mechanical integrity of the tip is important to assure reliable performance of the tip during contact as well as sliding. Crystalline silicon normally forms a tetrahedral structure, however, under high pressure it is known that the structure transforms to a different phase. This can cause a change in the contact phenomena. In this work, the silicon probe tip deformation process during nano-indentation was investigated by using molecular dynamics simulation. In addition, scribing simulation was carried out to observe the frictional characteristics of crystalline and amorphous silicon structures. The simulation results showed that the structure of silicon near the surface was permanently deformed at a contact stress of approximately 17 GN/m <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> and the deformation process could be monitored by observing the bond-angle distribution graph. It was also found that the atomic structure of the silicon tip in the contact region affected the frictional behavior of the tip with respect to fluctuation periodicity and magnitude.