Volume 86, Issue 3, 01 August 1999
Index of content:
- PLASMAS AND ELECTRICAL DISCHARGES (PACS 51-52)
86(1999); http://dx.doi.org/10.1063/1.370871View Description Hide Description
The temporal evolution of a collisionless ion matrix sheath in front of an electrode biased to a pulsed high negative voltage is investigated analytically and numerically. In the relaxation process a matrix extraction phase and a subsequent sheath expansion phase can be distinguished. For the matrix extraction phase we present an analytical model that is based on special solutions of the ion fluid equations and that is free of artificial assumptions. The model results in an explicit formula for the ion current to the electrode. The results are compared with numerical solutions of the ion fluid equations and show excellent agreement. By a simple parameter ansatz the model is extended to describe the sheath expansion phase.
Evaluation of self-bias potential distribution on a powered electrode of supermagnetron plasma apparatus86(1999); http://dx.doi.org/10.1063/1.370872View Description Hide Description
The distribution of self-bias potential on a powered electrode of a supermagnetron plasma system, where both electrodes are supplied phase-shifted radio frequency (rf) currents, was measured using five electrical probes buried in the electrode. For comparison, the same was measured for a conventional magnetron plasma system. Measurements were carried out with an Ar discharge at the pressure region of 4–50 mTorr. The data obtained with the supermagnetron and the conventional magnetron plasm systems were used to map the distribution on the powered electrodes of each plasma source. When the phase difference between rf currents applied to the two parallel electrodes of supermagnetron plasma system were changed, a drastic change of the is observed. The uniformity of the distribution is greatly improved when the phase difference between rf currents is varied from 0° to about 180°. The further increase of phase difference between two rf currents causes a decrease of the uniformity of the distribution. The uniformity of the obtained on the electrode of supermagnetron plasma source with 180° phase-shifted currents is observed to be superior to that of the conventional magnetron plasma source.
86(1999); http://dx.doi.org/10.1063/1.370873View Description Hide Description
Langmuir probetheory, adapted to magnetized, partially ionized, low temperature processing plasmas with radial diffusion dominated by electron-neutral collisions, was verified in electron cyclotron resonance (ECR) plasmas.Plasma parameters such as plasma potential, electron temperature,plasma density, and the ratio of electron saturation current to ion saturation current were measured by single-sided planar probe in various ECR plasmas ( He, Ar, and The neutral pressure was varied between 0.5 and 8.5 mTorr and the microwave power between 170 and 1250 W with good matching conditions; the reflected power was kept at less than 3% of the input power. The measured ratios of and other plasma parameters were consistent with the probe theory for pressures greater than 2.0 mTorr for various plasmas of Ar, He, and These results indicate that the electron-neutral collisional probe theory works well for magnetized ECR plasmas (magnetic flux densities of 0.8–1.0 kG).