AVS 46th International Symposium
    Plasma Science and Technology Division Monday Sessions
       Session PS-MoA

Paper PS-MoA4
Ion Energy Distribution Functions (IEDFs) in NF@sub3@ based Discharges with Various Diluents

Monday, October 25, 1999, 3:00 pm, Room 609

Session: Plasma Diagnostics I
Presenter: H. Hsueh, The Pennsylvania State University
Authors: H. Hsueh, The Pennsylvania State University
B.S. Felker, Air Products and Chemicals, Inc.
R.T. McGrath, The Pennsylvania State University
J.G. Langan, Air Products and Chemicals, Inc.
Correspondent: Click to Email
NF@sub 3@ based discharges are commonly used for cleaning residual SiO@sub 2@ and Si@sub 3@N@sub 4@ films formed on the walls of PECVD chambers. In order to find a balance between fast chamber cleaning and overly aggressive cleaning chemistries, which can lead to premature hardware failure, a fundamental understanding of the physical and chemical characteristics of the discharge is required. For this reason, we have measured the relative concentration of the ionic and neutral species, ion energy distribution functions (IEDFs), and the optical emission spectra (OES) present within capacitively coupled parallel plate discharges operated with NF@sub 3@ diluted with either Ar, He, Ne, or O@sub 2@. For reactor operation at a fixed power density of 1.35 W/cm@super 2@ and various NF@sub 3@ mole fractions, we found that when Ar was used as the diluent, the principal ion present was Ar@super +@ for all pressures investigated (0.5-1.5 Torr) and the IEDFs exhibit the highest average energies for all gas mixtures studied. In contrast, for similar reactor operating conditions using helium dilution, He@super +@ concentration was relatively low, with NF@sub 2@@super +@, F@super +@, F@sub 2@@super +@, and N@sub 2@@super +@ all having larger concentrations and the IEDFs for all species have lower energy peaks. When oxygen is used as the diluent, NO@super +@ is the major dominant positive ion species. The IEDFs are also lowered when oxygen is used. A summary of how changes in pressure and gas mixture affect IEDFs for all of the diluent options mentioned above will be presented. Optical emission spectra were also recorded as a reference for all of the discharge conditions investigated.