Dusty Plasma Studies in the Gaseous Electronics Conference Reference Cell

Abstract

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 date has been directed toward a better understanding of the role that electrostatic, ion drag, neutral fluid drag and gravitational forces play in governing the dynamic behavior of particle cloud motion. This has been accomplished by using laser light scattering (LLS) techniques to track the motion of suspended particle clouds in rf discharges. Also, statistical correlation’s in the fluctuation of scattered laser light intensity [dynamic laser light scattering (DLLS)] can be used to determine information 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 solid. 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 consistent with charge density wave (CDW) motion predicted for strongly coupled Coulomb liquids.

Dynamic light scattering study of phase transitions in three-dimensional complex plasmas

“…Previous studies [21] applied the DLS method on dusty plasmas to obtain diffusion constants and to determine particle sizes of nano-scaled dust particles. Hurd and Ho [22] observed free (ballistic) particle motion for polydisperse dust particles with a diameter below 200 nm with a Maxwell-Boltzmann velocity distribution.…”

Microcalorimetry of dust particles in a radio-frequency plasma

“…9 Many other researchers, e.g., Olthoff, Hebner, Anderson, Overzet, and McMillin, have used GEC cells to study the behavior of plasmas. [10][11][12][13][14] In our GEC cell we use argon and oxygen as feed gases and we operate between 5 and 60 Pa with a typical flow rate of 1 sccm. The supplied rf power is in the range of 2-45 W. The plasma is created with a frequency generator ͑Hewlett-Packard 33120A, 13.56 MHz͒, a wideband rf amplifier ͑Kalmus 150 C͒, and a homebuilt T-type matching network.…”

Dynamic Light Scattering on Complex Plasmas

“…In previous DLS experiments on complex plasmas to determined the diffusion constants, the dust grains were in a disordered state [92] or weakly coupled as for nano-scaled dust grains [16]. Here, the applicability of DLS to measure diffusion constants is extended for the first time to well ordered strongly coupled systems of large dust grains in RF-discharges.…”

“…This method is applied on dusty plasmas to obtain diffusion constants and to determine particle sizes of nano-scaled dust particles in [16]. Hurd et al [17] observed free particle motion for polydisperse dust particles with a diameter below 200 nm and measured a MaxwellBoltzmann velocity distribution.…”