Tribological Characteristics of Materials for MEMS/NEMS by Using Chemically Modified AFM Tip

Friction and adhesion tests were conducted in order to investigate the tribological characteristics of materials for MEMS/NEMS using AFM. AFM Si tips were chemically modified with self-assembled monolayer (SAM) derived from trichlorosilane like OTS and FOTS, and various materials such as Si, Al, Au, Cu, Ti, PMMA and PDMS were prepared for the tests. The friction and adhesion forces between AFM Si tip modified with SAM and MEMS/NEMS materials were measured and compared to those forces when AFM tip was uncoated. According to the results, however, the effect of SAM on the reduction of friction and adhesion could be changed with counterpart materials. After coating OTS on Si tip, the friction and adhesion forces on most of materials decreased while the friction and adhesion forces on PDMS rather increased than decreased. In case of the coating of FOTS, the friction and adhesion forces on PMMA540k and PDMS increased. Therefore, the adequate application of SAM would be required to effectively reduce friction and adhesion on each material for MEMS/NEMS.