AVS 51st International Symposium
    Plasma Science and Technology Wednesday Sessions
       Session PS-WeA

Paper PS-WeA1
Excitation Mechanisms in Low Pressure Capacitively Coupled Discharges

Wednesday, November 17, 2004, 2:00 pm, Room 213A

Session: Plasma Diagnostics
Presenter: G.F. Franz, University of Applied Sciences, Germany
Authors: G.F. Franz, University of Applied Sciences, Germany
M.K. Klick, Advanced Semiconductor Instruments, Germany
Correspondent: Click to Email
The dominating excitation mechanisms in capacitively coupled discharges are ohmic heating (mainly to electrons in the bulk, and, at high powers, also to the ions in the sheath) and stochastic heating (thermalization of the electric energy of the sheath). The latter process will gradually enhance its importance when the discharge pressure is reduced below a threshold value of about 100 mTorr. That means that the electron energy distribution function (EEDF) in this regime will be governed by stochastic heating. This is also the pressure range in which reactive ion etching takes place. Measurements with self-excited electron resonance spectroscopy (SEERS) in various plasmas reveal that stochastic heating will strongly depend on the nature of the gas (atomic or molecular, electronegative or electropositive). Since ohmic heating scales with discharge pressure whereas stochastic heating is nearly pressure independent, both the heating mechanisms can be separated. New results are presented which have simultaneously measured with VI- and Langmuir probes as well as with optical emission spectroscopy (OES) with traces of rare gases and are eventually compared with models created by Lieberman, Godyak, and Klick.