High-Efficiency PFC Abatement System Utilizing Plasma Decomposition and Ca(OH)$_{2}$ /CaO Immobilization
In order to minimize contributions to global warming, it is important to develop a perfluorocompound (PFC) abatement system that can remove PFCs effectively with low electric power. We have developed a new PFC abatement system consisting mainly of a 2-MHz ICP plasma source and two Ca(OH)2/CaO columns operated under a decompression pressure. Reactive fluorinated compounds including SiF4 are immobilized in the Ca(OH)2/CaO columns without a water scrubber. Stable compounds such as CF4 are excited by the 2-MHz ICP plasma. When the emissions from an Si oxidation film etching process chamber were treated by this abatement system, F2 equivalent removal efficiency was 99.6%, which was about one order of magnitude larger than that of a conventional abatement system. But the CO2 equivalent removal efficiency was calculated to be 91.4% because over 95% of CO2 equivalent emissions were caused by the plasma source power consumption of 2.4 kWh. It means that minimization of the plasma source power consumption, depending on PFC emissions, is a very effective method of minimizing contributions to global warming in a manner similar to improving the PFC removal efficiency.
PECVD Chamber Cleaning End Point Detection (EPD) Using Optical Emission Spectroscopy Data
In-situ optical emission spectroscopy (OES) is employed for PECVD chamber monitoring. OES is used as an addon sensor to monitoring and cleaning end point detection (EPD). On monitoring plasma chemistry using OES, the process gas and by-product gas are simultaneously monitored. Principal component analysis (PCA) enhances the capability of end point detection using OES data. Through chamber cleaning monitoring using OES, cleaning time is reduced by 53%, in general. Therefore, the gas usage of fluorine is also reduced, so satisfying Green Fab challenge in semiconductor manufacturing.
HYPERGOLIC REACTION MECHANISMS OF CATALYTICALLY PROMOTED FUELS WITH ROCKET GRADE HYDROGEN PEROXIDE
Abstract The coupling of the physical and chemical processes controlling the ignition delays (τ ign ) of hypergolic propellants complicates the direct analysis of the transient ignition processes. The transport properties of both the propellants and the ambient gas, and the heat of vaporization and reaction affect τ ign and must be considered experimentally. Furthermore, since hypergolic ignition occurs, by definition, on contact, the mechanics of initial contact and subsequent mixing can affect τ ign and must also be considered. Experimental results from a study of the hypergolic ignition of a catalytically promoted fuel with rocket grade hydrogen peroxide (RGHP) are presented. Statistical analysis of the experimental data was conducted to evaluate the relative effects of RGHP concentration, initial ambient pressure, and the ambient gas on τ ign . At RGHP concentrations of less than 92% in water, stable ignition was difficult to achieve. At sufficiently high Lewis number, an oscillatory ignition process is observed. A phenomenological model comprising mixing, RGHP decomposition, fuel heating and vaporization, and auto-ignition is presented and compared to the experimental results.