Analytic sheath resolution in high density plasma source simulations
- Lawrence Livermore National Lab., CA (United States)
Capacitive coupling involves the physics of external RF voltages coupling to the plasma through an oscillating sheath. For high density plasmas, the sheath dimension is much smaller than the scale lengths of density and field variation in the bulk of the plasma. To avoid costly numerical resolution of the sheath, the authors use analytic models to determine sheath voltage drops and power deposition due to Ohmic and stochastic heating at the sheaths. They use Metze`s sheath model because it provides an ODE for the sheath voltage drop which can be directly incorporated into the numerical solution of Poisson equation. The analytic model reproduces the sheath drop fairly well. They use Lieberman`s model to calculate Ohmic heating due to the substrate RF current and stochastic heating due to electrons bouncing of the oscillating substrate sheath. For a 13.56 MHz, 4 eV, 10 mTorr argon discharge 6 cm long with 8 inch substrate, P{sub stoc} = 0.045(V{sub dc}/T{sub e}) W and P{sub ohm} = 0.078(V{sub dc}/T{sub e}){sup 1/2} W, where V{sub dc} is the time-average sheath voltage. These scalings indicate that stochastic and Ohmic heating at the substrate is typically only a few percent of the power coupled inductively.
- DOE Contract Number:
- W-7405-ENG-48
- OSTI ID:
- 160763
- Report Number(s):
- CONF-950612--; ISBN 0-7803-2669-5
- Country of Publication:
- United States
- Language:
- English
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