SIMULATION OF THE FORMATION OF 2-DIMENSIONAL COULOMB LIQUIDS AND SOLIDS IN DUSTY PLASMAS

Dust particle transport in low-temperature plasmas has recently receiv ed considerable attention due to the desire to minimize contamination of wafers during plasma processing of microelectronics devices, Laser light scattering observations of dust particles near wafers in reactiv e-ion-etching (RIE) radio frequency (rf) discharges have revealed clou ds which display collective behavior. These observations have motivate d experimental studies of the Coulomb liquid and solid properties of t hese systems. In this paper, we present results from a two-dimensional model for dust particle transport in RIE rf discharges in which we in clude particle-particle Coulomb interactions. We predict the formation of Coulomb liquids and solids. These predictions are based both on va lues of Gamma>2 (liquid) and Gamma>170 (solid), where Gamma is the rat io of electrostatic potential energy to thermal energy, and on crystal -like structure in the pair correlation function. We find that Coulomb liquids and solids composed of trapped dust particles in RIE discharg es are preferentially formed with increasing gas pressure, decreasing particle size, and decreasing rf power, We also observe the ejection o f particles from dust crystals which completely fill trapping sites, a s well as lattice disordering followed by annealing and refreezing. (C ) 1997 American Institute of Physics.