Nanotribological properties of silicon nano-pillars coated by a Z-DOL lubricating film

• Published in: Journal of mechanical science and technology Vol. 24; no. 1; pp. 59 - 65
• Main Authors: Pham, Duc Cuong, Na, Kyunghwan, Yang, Sungwook, Kim, Jinseok, Yoon, Eui-Sung
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Heidelberg Korean Society of Mechanical Engineers 01.01.2010; Springer Nature B.V; 대한기계학회
• Subjects: Adhesion; Applied sciences; Control; Dynamical Systems; Engineering; Exact sciences and technology; Friction; Friction, wear, lubrication; Industrial and Production Engineering; Instruments, apparatus, components and techniques common to several branches of physics and astronomy; Invited Paper; Lubrication; Machine components; Mechanical Engineering; Mechanical engineering. Machine design; Mechanical instruments, equipment and techniques; Micromechanical devices and systems; Nanocomposites; Nanomaterials; Nanostructure; Physics; Pillars; Silicon; Vibration; 기계공학; AFM; Surface modification; Friction; Adhesion; Z-DOL; Micro/Nano; Atomic force microscopy; Organic perhalocompound; Tetrafluoroethylene polymer; Fluorine containing polymer; Mechanical contact; Ether polymer; Experimental study; Ethylene oxide polymer; Lubricating film; Nanometer scale; Surface forces; Silicon; Dip coating; Photolithography; Microelectromechanical device; Surface energy; Wafer; Tribology
• ISSN: 1738-494X; 1976-3824
• DOI: 10.1007/s12206-009-1128-3

This paper reports a novel approach for improving the nanotribological properties of silicon (Si) surfaces by topographically and chemically modifying the surfaces. In the first step, Si (100) wafers were topographically modified into nano-pillars by using the photolithography and reactive ion etching (RIE) techniques. Various patterns, including nano-pillars of varying diameters and pitches (distance between pillars), were fabricated. Then, the patterns were coated with a Z-DOL (perfluoropolyether (PFPE)) lubricating film using a dipcoating technique, and this process was followed by thermal treatment. These modified surfaces were tested for their nanotribological properties, namely adhesion and friction forces, using an atomic force microscope (AFM). The results showed that the topographical modification and Z-DOL coating each independently reduced the adhesion and friction forces on the Si surfaces. However, the combination of the two surface treatments was most effective in reducing these forces. This is attributed to the combined effects of the reduction in the real area of contact due to patterning and the low surface energy of the Z-DOL lubricant. Further, it was found that adhesion and friction forces of the surfaces with combined modification varied significantly depending on the diameter of the pillars and the pitch. It is proposed that such a combination of surface modifications promises to be an effective method to improve the nanotribological performance of miniaturized devices, such as MEMS, in which Si is a typical material.