DUSTY PLASMA STUDIES IN THE GASEOUS ELECTRONICS CONFERENCE REFERENCE CELL

Particle ''dust'' in processing plasmas is of critical concern to the semiconductor industry because of the threat particles pose to device yield. A number of important investigations into the formation, growth , charging, transport and consequences of particulate dust in plasmas have been made using the Gaseous Electronics Conference Reference Cell as the reactor test-bed. The greatest amount of work to dare has been directed toward a better understanding of the role that electrostatic , ion drag, neutral fluid drag and gravitational forces play in govern ing the dynamic behavior of particle cloud motion. This has been accom plished by using laser light scattering (LLS) techniques to track the motion of suspended particle clouds in rf discharges. Also, statistica l correlation's in the fluctuation of scattered laser light intensity [dynamic laser light scattering (DLLS)] can be used to determine infer mation about particle size, motion, and growth dynamics. These results are reviewed, along with recent work demonstrating that charged dust particles in a plasma can form a strongly coupled Coulomb liquid or so lid. New results from DLSS experiments performed in the Reference Cell are presented that show process-induced dust particles confined in an electrostatic trap exhibit low-frequency oscillatory motion consisten t with charge density wave (CDW) motion predicted for strongly coupled Coulomb liquids.