In-Vacuo Surface Analytical Study of Diamond Nucleation on Copper Vs. Silicon
- PDF / 457,772 Bytes
- 6 Pages / 420.48 x 639 pts Page_size
- 42 Downloads / 213 Views
IN-VACUO SURFACE ANALYTICAL STUDY OF DIAMOND NUCLEATION ON COPPER VS. SILICON S. D. WOLTER, B. R. STONER, G.-H. M. MA, AND J. T. GLASS Department of Materials Science and Engineering, North Carolina State University, Raleigh, N.C.,27695-7919 ABSTRACT A study was performed on polycrystalline copper versus that of Si(100) utilizing a negative substrate bias to enhance diamond nucleation. The biasing pretreatment and subsequent growth of the diamond were performed via microwave plasma chemical vapor deposition and the initial stages of nucleation were characterized by in-vacuo surface analysis. The biasing pretreatment step proved to have a tremendous influence on the nucleation density pertaining to Si(100) substrates, however, the nucleation density on polycrystalline copper was only increased slightly. A highly graphitic surface coverage of roughly 10A was evident on the copper substrates prior to the detection of diamond and was quite stable in thickness in as early as 15 minutes of biasing. The Si(100) substrates, however, were characterized by the formation of a carbide with some form of nondiamond carbon present on the surface throughout the biasing pretreatment. INTRODUCTION It has been observed that the properties inherent to the substrate have an influence on the diamond nucleation phenomenon. Past research has indicated that the time prior to the formation of the initial nuclei (i.e., the incubation time) and the rate at which the nuclei are formed vary depending on the substrate material used.1 ' 2 Though much work has been involved in the study of the growth mechanisms, a thorough understanding of the nucleation phenomenon is lacking and is essential to the fabrication of high quality diamond films. Once models for the nucleation of diamond are established, it may then be possible to provide conditions ideal for heteroepitaxial nucleation and growth. The purpose of the current study is to fully characterize bias-enhanced diamond nucleation on a non-carbide forming substrate by in-vacuo surface analysis. The results of this study will be compared with the results from the work performed by Stoner et al. 3 on Si(100), a carbide forming substrate. An 1 enhanced nucleation of diamond on Si(100) has been observed experimentally' ' 5 utilizing this biasing pretreatment step, and the same experimental conditions in Stoner's work will be maintained to study the nucleation phenomenon of diamond grown on polycrystalline copper. The potential for this biasing pretreatment technique to be used for depositing heteroepitaxial diamond films was evident when used to enhance nucleation on f3-SiC. 6 It will be of interest to observe whether or not this technique has merit with respect to non-carbide forming substrates. A comparison of these two studies should yield a better understanding of diamond nucleation in general.
Mat. Res. Soc. Symp. Proc. Vol. 270. @1992 Materials Research Society
348
EXPERIMENTAL Sample preparation and in-situ biasing pretreatment Low pressure diamond growth was performed by microwave plasma
Data Loading...
