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.
Characterization of MOSFETs intrinsic performance using in-wafer advanced Kelvin-contact device structure for high performance CMOS LSIs
In this work, a new MOSFETs characterization method utilizing in-wafer Kelvin contact device structure is developed. The developed method can eliminate the parasitic series resistances in MOSFETs and allows us to characterize the short channel transistor intrinsic current- voltage characteristics as well as the quantitative effects of the parasitic series resistance to the device performance, very stably and accurately. The developed analysis is useful for the characterization and parameter extractions of fabricated MOSFETs for the device/process development and optimization of ultra-thin gate insulator short channel CMOS LSIs for higher performance.
NO/sub x/ removal process using pulsed discharge plasma
Nonequilibrium plasma can be used to promote chemical reactions that reduce the emission of gaseous pollutants, such as NO/sub x/, produced by coal-burning power plants or by diesel engines. Laboratory experiments were carried out to study the decrease of NO/sub x/ in simulated flue gases (initial concentration of NO: 200 to 800 ppms, O/sub 2/: 10%; N/sub 2/ was the balance gas) by means of a pulsed-discharge plasma generated in a cylinder-type reactor (outer electrode; 20 mm diameter). A rotary spark gap provided square-wave high voltages up to 25 kV, at a frequency of 250 Hz, to corona electrodes of 0.1, 3.3, and 6.4 mm diameter. The tests were performed at various temperatures (ambient to 220 degrees C) and constant residence time (0.6 s). The removal performance depended on the size of the discharge electrode and was better at room temperature. The addition of C/sub 2/H/sub 4/ significantly enhanced the removal performance; the concentration of NO/sub x/ decreased from 800 ppm to 300 ppm in the discharge. The by-products of this process were analyzed using infrared spectroscopy. No traces of toxic gases could be detected.<<ETX>>