AVS 50th International Symposium
    Microelectromechanical Systems (MEMS) Tuesday Sessions
       Session MM-TuM

Paper MM-TuM3
Engineering the Surface Properties of Ultrananocrystalline Diamond for High-Performance MEMS Devices

Tuesday, November 4, 2003, 9:00 am, Room 320

Session: Development and Characterization of MEMS and NEMS Materials
Presenter: A.V. Sumant, University of Wisconsin, Madison
Authors: A.V. Sumant, University of Wisconsin, Madison
D.S. Grierson, University of Wisconsin, Madison
J.E. Gerbi, Argonne National Laboratory
J.A. Carlisle, Argonne National Laboratory
O. Auciello, Argonne National Laboratory
R.W. Carpick, University of Wisconsin, Madison
Correspondent: Click to Email
Characterization of MEMS and NEMS devices at small length scales is extremely important in order to understand the factors that dictate the performance of these devices. Ultrananocrystalline diamond (UNCD), in particular, has exceptional physical, electrical, chemical and tribological properties (nearly equivalent to those of single crystal diamond). UNCD is being considered as one of the most promising materials for the fabrication of high performance MEMS devices. However, little is known about the surface chemistry of this material, and how such surface chemistry will affect the UNCD performance, particularly in case of rolling or sliding contacts at both the micro and nano level. We have carried out detailed, systematic studies of UNCD thin films by various analytical techniques including Auger electron spectroscopy (AES), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, and atomic force microscopy (AFM) to understand the chemical nature, phase, and microstructure of the UNCD surface. We have found that there is a significant difference in the structural and chemical properties between the as-grown UNCD top surface and the underside of the film as revealed after etching away the substrate. Characterizing the underside of the film is particularly important because in most cases (e.g. micro-engines and cantilever based switches), the underside of the film makes contact with the underlying surface below. We will discuss how these properties are influenced by various aspects of the microwave PECVD growth process, including the initial nucleation pre-treatment and the gas chemistry used during growth, and how one can engineer the surface by tuning these growth parameters. Finally, we will discuss how such changes may affect UNCD performance at MEMS length scales.