TY - JOUR
T1 - Charging, transport and heating of particles in radiofrequency and electron cyclotron resonance plasmas
AU - Graves, D. B.
AU - Daugherty, J. E.
AU - Kilgore, M. D.
AU - Porteous, R. K.
PY - 1994
Y1 - 1994
N2 - Once particles are formed or injected into plasmas used for materials processing, such as in plasma etching, plasma-assisted chemical vapour deposition or sputtering plasma systems, the nature of particle transport will largely determine whether a processing surface will be contaminated. We investigate the situation in which the particle density is low enough to ignore particle-particle and particle-plasma interactions. Emphasis is placed on obtaining expressions for the forces experienced by particles. These expressions depend on the local plasma condition: plasma density, electron temperature, positive ion directed and random kinetic energies, electric field and ion mass. We apply a model of an electron cyclotron resonance discharge to prediction of the existence and nature of particle trapping. Model predictions indicate that a high-density source such as an electron cyclotron resonance discharge is unlikely to trap particles mainly because of the large ion drag force sweeping particles out of the discharge. Finally, we present a model of particle heating in discharges. Under typical radiofrequency discharge conditions, particles are generally predicted to be near the neutral gas temperature in the discharge. We have conducted experiments and found results in agreement with these predictions. However, under conditions typically encountered in high-density plasma sources such as an electron cyclotron resonance source, the model predicts that particles may be heated to temperatures of two to three times room temperature.
AB - Once particles are formed or injected into plasmas used for materials processing, such as in plasma etching, plasma-assisted chemical vapour deposition or sputtering plasma systems, the nature of particle transport will largely determine whether a processing surface will be contaminated. We investigate the situation in which the particle density is low enough to ignore particle-particle and particle-plasma interactions. Emphasis is placed on obtaining expressions for the forces experienced by particles. These expressions depend on the local plasma condition: plasma density, electron temperature, positive ion directed and random kinetic energies, electric field and ion mass. We apply a model of an electron cyclotron resonance discharge to prediction of the existence and nature of particle trapping. Model predictions indicate that a high-density source such as an electron cyclotron resonance discharge is unlikely to trap particles mainly because of the large ion drag force sweeping particles out of the discharge. Finally, we present a model of particle heating in discharges. Under typical radiofrequency discharge conditions, particles are generally predicted to be near the neutral gas temperature in the discharge. We have conducted experiments and found results in agreement with these predictions. However, under conditions typically encountered in high-density plasma sources such as an electron cyclotron resonance source, the model predicts that particles may be heated to temperatures of two to three times room temperature.
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U2 - 10.1088/0963-0252/3/3/029
DO - 10.1088/0963-0252/3/3/029
M3 - Article
AN - SCOPUS:0001226369
SN - 0963-0252
VL - 3
SP - 433
EP - 441
JO - Plasma Sources Science and Technology
JF - Plasma Sources Science and Technology
IS - 3
M1 - 029
ER -