Volume 86, Issue 1, 01 July 1999
Index of content:
- PLASMAS AND ELECTRICAL DISCHARGES (PACS 51-52)
86(1999); http://dx.doi.org/10.1063/1.370707View Description Hide Description
The free, steady state, two-dimensional radial plasma flow initiated between a pair of disk-shaped electrodes of a hot anode vacuum arc was analyzed in the hydrodynamic approximation. Studies include the influence of the self-magnetic field on the plasma density,velocity, radial spreading of the arc current and potential distribution. The free plasma boundary was calculated by solving the equations for the normal and tangential velocity components at the free boundary. It was found that the plasma significantly expands over a radial distance of about half of the interelectrode gap counted from the electrode edge and the plasma density in the center plane decreases by factor of 2, whereas the density of the fringe current decreases by a factor of 10. The self magnetic field does not influence the plasma flow and current spreading at radial distances larger than the interelectrode gap. The potential distribution is strongly nonsymmetric with respect to the central plane due to the influence of the plasma density gradients on the current spreading.
Investigation of dose uniformity on the inner races of bearings treated by plasma immersion ion implantation86(1999); http://dx.doi.org/10.1063/1.370708View Description Hide Description
Plasma immersion ion implantation(PIII) is an effective technique for the surface modification of industrial components possessing an irregular shape. We have recently used PIII to treat a real industrial ball bearing to enhance the surface properties of the race surface on which the balls roll. The implantation dose uniformity along the groove is assessed using theoretical simulation and experiments. The two sets of results agree very well, showing larger doses near the center. However, the highest dose is not observed at the bottom or center of the groove, but rather offset toward the side close to the sample platen when the bearing is placed horizontally. The minimum dose is observed near the edge or corner of the groove and our model indicates that it is due to the more glancing ion incidence as a result of the evolution of the ion sheath near the corner. The dose nonuniformity along the groove surface is about 40% based on our experimental data.
86(1999); http://dx.doi.org/10.1063/1.370709View Description Hide Description
In a coplanar plasma display panel the discharges in each pixel are sustained between two parallel electrodes on the same substrate. A third electrode perpendicular to the sustaining electrodes and placed on a facing substrate is used to address the pixel. A self-consistent two-dimensional model of the microdischarge has been used to simulate and study the addressing and sustaining phases in an alternating current coplanar cell. The formation and decay of the transient plasma during the address and sustain discharge pulses are described. The time evolution of the charges on the dielectricsurfaces above each electrode is also discussed and the model is used to derive the voltage margins of the address and sustain regimes.
Self-consistent microwave field and plasma discharge simulations for a moderate pressure hydrogen discharge reactor86(1999); http://dx.doi.org/10.1063/1.370710View Description Hide Description
A self-consistent two-dimensional model of the electromagnetic field and the plasma in a hydrogen discharge system has been developed and tested in comparison to experimental measurements. The reactor studied is a 25 cm diameter resonant cavity structure operating at 2.45 GHz with a silica belljar of 10 cm diameter and 17 cm height contained within the microwave cavity. The inside of the belljar where the discharge occurs contains a substrate holder of 5 cm diameter that is used to hold substrates for diamond deposition. The electromagnetic field model solves for the microwave fields using a finite difference time-domain solution of Maxwell’sequations. The plasma model is a three energy mode (gas, molecular vibration, and electron) and nine species ( H, electron) model which accounts for non-Boltzmann electron distribution function and has 35 reactions. Simulated characteristics of the reactor in two dimensions include gas temperature, electron temperature, electron density, atomic hydrogen molar fraction, microwave power absorption, and microwave fields. Comparisons of the model are made with close agreement to several experimental measurements including coherent anti-Stokes Raman Spectroscopy measurement of temperature versus position above the substrate, Doppler broadening optical emission spectroscopy(OES)measurements of H temperature versus pressure, actinometry measurements of the relative H atom concentration, OES intensity measurements versus position, and microwave electric field measurements. The parameter range studied includes pressures of 2500–11 000 Pa, microwave powers of 300–2000 W, and three vertical positions of the substrate holder.
Model of point-of-use plasma abatement of perfluorinated compounds with an inductively coupled plasma86(1999); http://dx.doi.org/10.1063/1.370711View Description Hide Description
Point-of-use plasma abatement (PPA) has been proposed as one way to eliminate perfluorinated compound (PFC) emission from various tools used in integrated circuitmanufacturing. PPA employs a high density plasma between the process tool turbomolecular pump and the backing pump. Oxygen is added to the process tool effluent upstream of the PPA tool. The mixture of oxygen and PFC-containing tool effluent enters the PPA tool and the PFCs are converted to products that can be scrubbed downstream of the backing pump. In this article, we present a model for the PPA tool operation, illustrating the principles with a mixture of A plasmamodel is coupled to a neutral transport and reactionmodel, including electron-impact molecular dissociation and subsequent gas phase chemistry.