AVS 46th International Symposium
    Thin Films Division Monday Sessions
       Session TF-MoA

Paper TF-MoA7
Gas Phase Dynamics of Copper Ionized Metal Plasmas

Monday, October 25, 1999, 4:00 pm, Room 615

Session: Fundamentals and Applications of Ionized PVD
Presenter: Y. Andrew, University of Wisconsin, Madison
Authors: Y. Andrew, University of Wisconsin, Madison
I.C. Abraham, University of Wisconsin, Madison
Z. Lu, University of Wisconsin, Madison
T.G. Snodgrass, University of Wisconsin, Madison
A.E. Wendt, University of Wisconsin, Madison
J.H. Booske, University of Wisconsin, Madison
P.L.G. Ventzek, Motorola
S. Rauf, Motorola
Correspondent: Click to Email
Copper ionized metal plasmas are of interest for the Damascene process of interconnect fabrication, in which trench and via structures are filled with copper. Used to deposit seed layers for subsequent electroplating, ionized metal plasmas produce films with enhanced conformality compared to conventional physical vapor deposition (PVD) processes. Improved understanding of the performance potential and limitations of this process motivate this study to characterize discharge properties through experiment and simulation. We examine a system consisting of a DC powered 15 cm D copper sputter source and an RF induction plasma powered by a single turn 36 cm D loop antenna internal to the vacuum chamber, with an argon pressure of 10-50 mTorr. Measurements include plasma parameters, ion and neutral copper flux at the substrate, RF and DC potentials on the antenna and in the plasma, and spectroscopic measurements of ground state and metastable copper as well as argon metastable concentrations in the gas phase. The simulations have been done using the Hybrid Plasma Equipment Model, a comprehensive plasma equipment modeling tool developed at the University of Illinois. The plasma is treated as a fluid in this model except for thermal copper neutrals sputtered from the target, for which a Monte Carlo simulation is used. The extensive data set includes some surprising observations. For example, both experiment and simulation show that for some operating conditions, the copper metastable density is substantial compared to that of the ground state population. Measurements and simulation will also address electrical measurements on the system, including a substantial but unexpected DC self-bias voltage on the antenna. Finally, by comparing copper fluxes measured directly and computed from spectroscopically determined gas phase concentrations, we can infer the temperature of the copper in the gas phase, which is found to increase substantially with RF power to the plasma.