AVS 45th International Symposium
    Electronic Materials and Processing Division Wednesday Sessions
       Session EM-WeM

Paper EM-WeM10
Studies on Passivation Behavior of Tungsten in Application to Chemical Mechanical Polishing

Wednesday, November 4, 1998, 11:20 am, Room 316

Session: Fundamentals of Si Cleaning and CMP
Presenter: D. Tamboli, University of Central Florida
Authors: D. Tamboli, University of Central Florida
S. Seal, University of Central Florida
A. Kale, University of Central Florida
V. Desai, University of Central Florida
Y. Obeng, Bell Laboratories, Lucent Technologies
A. Maury, Bell Laboratories, Lucent Technologies
Correspondent: Click to Email
Chemical mechanical polishing (CMP) is considered to be the enabling technology for meeting the planarization requirements in < 0.35 micron feature sized multi-level devices and interconnects in semiconductor industries. Considerable importance is given to the role played by the passive oxide film formation on the surface in CMP process.@footnote 1@ However, there are very few studies available in open literature regarding the characterization of surface reaction products in terms of chemistry and thickness of the reaction layers.@footnote 2@ In this research study, X-ray Photoelectron Spectroscopy is used to understand modification of surfaces (i.e. oxide layers) during the CMP process. Tungsten wafers are treated in static solutions with varying pH, oxidizer levels, temperature and applied potential in order to determine the effect of these parameters on the chemistry of the passive oxide layers. XPS measurements are employed to probe the chemical and stoichiometric changes (e.g. WO@sub 2@/WO@sub 3@ ratio, presence of any hydroxides, etc.) in these surface films treated under various conditions. Valence band XPS studies on W(4f) and O (2p) states are performed to determine the electronic structure of the oxide layer and its relevance to passivation. These results are compared with the electrochemical studies carried out both ex-situ and in-situ during polishing. @FootnoteText@ @Footnote 1@F.B. Kaufman, et al., J. Electrochem. Soc., 138, 3460, 1991 @Footnote 2@E.A. Kneer , et al., J. of the Electrochem. Soc., 143, 4095, Dec 1996