Volume 96, Issue 7, 01 October 2004
Index of content:
- PLASMAS AND ELECTRICAL DISCHARGES (PACS 51-52)
96(2004); http://dx.doi.org/10.1063/1.1789276View Description Hide Description
Microtrenching during plasma etching was characterized by using a generalized regression neural network(GRNN).Plasma etching of oxide films was conducted in a magnetically enhanced reactive ion etch system. The etch process was characterized by means of a fractional factorial experiment. The process parameters concerned include flow rate, flow rate, radio frequency power, and pressure. Radicals collected with a dc bias were analyzed by optical emission spectroscopy while being correlated to the microtrenching depth (MD). A genetic algorithm (GA) was used to search an optimized set of multiparametrized spreads. The resultant prediction model had a root mean-squared error of 0.031 Å/min. Compared to conventional GRNN and statistical regression models, the GA-GRNN demonstrated more accurate predictions of more than 30% and 70%, respectively. The MD variation with the pressure or flow rate was attributed to the more dominant role of polymer deposition over chemical etching as illustrated by a high correlation with [CF]/[F]. For variations in the rf power, the profile change played a critical role in understanding MD.
96(2004); http://dx.doi.org/10.1063/1.1789274View Description Hide Description
Analysis of the electrical double layer at the electrode-water interface for voltages close to the breakdown point has been carried out based on a static, Monte Carlo approach. It is shown that strong dipole realignment, ion-ion correlation, and finite-size effects can greatly modify the electric fields and local permittivity (hence, leading to optical structure) at the electrodeinterface. Dramatic enhancements of Schottky injection, providing a source for electronic controlled breakdown, are possible. It is also shown that large pressures associated with the Maxwell stress tensor would be created at the electrode boundaries. Our results depend on the ionic density, and are in keeping with recent observations. A simple, perturbative analysis shows that high field regions with a sharp variation in permittivity can potentially be critical spots for instability initiation. This suggests that the use of polished electrodes, or composite materials, or alternative nonpolar liquids might help enhance high-voltage operation.