AVS 47th International Symposium
    MEMS Thursday Sessions
       Session MM-ThA

Paper MM-ThA9
Investigation of the Friction and Adhesion Properties of BPT and BPTC Self-assembled Monolayers by AFM

Thursday, October 5, 2000, 4:40 pm, Room 309

Session: Material Science of MEMS
Presenter: H. Liu, The Ohio State University
Authors: H. Liu, The Ohio State University
B. Bhushan, The Ohio State University
W. Eck, University of Heidelberg, Germany
V. Stadler, University of Heidelberg, Germany
Correspondent: Click to Email
Self-assembled monolayers (SAMs) are considered to be good candidate lubricants for microelectromechanical systems (MEMS). It is important to understanding the relationship between the structure and tribological performance for molecular tailoring to achieve efficient lubrication. For this purpose, biphenyl-4-thiol (BPT), and cross-linked biphenyl thiol (BPTC) were prepared on a gold sublayer. The cross-linking of BPT was carried out by low energy electron irradiation. Structure characterization shows that cross-links were formed between neighboring phenyl groups. The topography, adhesion, and friction properties of Si, Au, BPT and BPTC were studied by atomic force microscopy (AFM) with silicon nitride tip. It was found that both BPT and BPTC exhibited lower adhesion and friction than Si. But the coefficient of friction of BPTC are higher than BPT. The larger coefficient of friction of BPTC is believed to be caused by its rigid cross-linked structure. The study also found that the topography of different films have different contribution to the frictions of films. For Au and BPTC, friction is affected by surface slope, but for BPT the higher surface areas have low friction. A relationship between wear resistance of the low friction phase of BPT and its size was found.