IUVSTA 15th International Vacuum Congress (IVC-15), AVS 48th International Symposium (AVS-48), 11th International Conference on Solid Surfaces (ICSS-11)
    Plasma Science Friday Sessions
       Session PS-FrM

Paper PS-FrM5
Temporally Resolved Measurement of Electron Temperature, Relative Electron Density, and Atomic Fluorine Density during Fluorocarbon/Rare-gas Plasma Etching of SiO@sub 2@, using Optical Emission Spectroscopy

Friday, November 2, 2001, 9:40 am, Room 104

Session: Diagnostics III
Presenter: M.J. Schabel, Bell Laboratories, Lucent Technologies
Authors: M.J. Schabel, Bell Laboratories, Lucent Technologies
V.M. Donnelly, Agere Systems
W.W. Tai, Agere Systems
A. Kornblit, Agere Systems
Correspondent: Click to Email
Measuring the time-resolved behavior of processing plasmas is important for determining process end-points, tool health and process faults. One commonly used approach is to monitor the optical emission for changes that correlate conditions. Recently, we have demonstrated that the plasma emission may also be used to characterize the time-averaged behavior of fundamental plasma properties, including electron temperature (T@sub e@), relative electron density (n@sub e@) and fluorine atom concentration (n@sub F@), through the application of advanced optical emission spectroscopy. Here we have used trace rare gas optical emission spectroscopy and rare gas actinometry to measure T@sub e@, n@sub e@, and n@sub F@ at ~2 second increments in an inductively-coupled commercial plasma reactor. The temporal behavior was evaluated over a complete plasma process cycle, which included plasma strike, stabilization, chamber seasoning, silicon dioxide etch, and an oxygen chamber clean and photoresist strip. Run to run repeatability of T@sub e@, n@sub e@, n@sub F@, and O-atom density was evaluated for each step in the cycle. T@sub e@ was found to be repeatable to within ± 0.5 eV for constant step conditions. The silicon dioxide etch step, comprised of C@sub 2@F@sub 6@, C@sub 4@F@sub 8@, a carrier gas, and a trace rare gas mixture (equal parts He, Ne, Ar, Kr, and Xe), was evaluated over variations in pressure (10-90 mTorr), flowrate (120-600 sccm), and carrier gas composition (0-100% Ar, balance Ne). Corresponding measurements of etch rates and sidewall angles were found to range between 2-12 kÅ/min and 85-90°, respectively. Correlations between plasma operating conditions, fundamental plasma parameters, and etch performance will be presented.