AVS 49th International Symposium
    Plasma Science Monday Sessions
       Session PS2-MoA

Paper PS2-MoA1
Ion Flux Uniformity in Large Area High Frequency Capacitive Discharges

Monday, November 4, 2002, 2:00 pm, Room C-105

Session: Plasma Processing for Large Area Substrates
Presenter: A. Perret, Ecole Polytechnique, France
Authors: A. Perret, Ecole Polytechnique, France
P. Chabert, Ecole Polytechnique, France
J. Jolly, Ecole Polytechnique, France
J.P. Booth, Ecole Polytechnique, France
J. Guillon, Ecole Polytechnique, France
Correspondent: Click to Email
Etching and thin film deposition using capacitive RF discharges at 13.56 MHz are routinely used for Flat Panel Display fabrication. The current trend in FPD technology is to increase the substrate size (> 1m2) while keeping high throughput (> 50 glass/hour). Very High Frequency (VHF) plasma excitation promises to provide faster processes whilst avoiding damage due to high energy ion bombardment. However, the reactor size may no longer be negligible with respect to the wavelength of the RF electromagnetic wave, causing non-uniformity in the plasma density across the reactor. The physical origin of this phenomenon is the beginning of a spatial standing wave within the reactor. The standing wave effect will become more important as the frequency is increased. Other phenomena causing non-uniformity will appear if the skin depth become small compared to the reactor size. We will present an experimental study of the ion flux uniformity of a plasma created in a large area capacitive discharge driven at frequencies of 13.56 to 60 MHz. The discharge was produced between two square plates (40cm x 40cm) separated by a distance of 8 cm. The ion flux variation across the reactor is measured by a system composed of 64 electrostatic probes inserted in the grounded upper electrode and biased negatively. The probes are regularly spaced and the time to read all probes is less than 2 seconds. The experimental results will be compared with a recently proposed model (Lieberman et al. Plasma Sources Science and Technology, accepted 2002).