Papers by Author: Seung Soo Hong

Abstract: The Korea Research Institute of Standards and Sciences has developed and maintained leak standards systems, and has accumulated much data on leak standards that have been disseminated during calibration and testing services. We have found that the indicative value of a leak detector and a halogen leak detector varies a lot, depending on the conditions encountered during sniffer mode operation. Therefore, to measure the reliability of the leak rate or when performing a leak test, proper test conditions are necessary. In addition, we found that the reliability increased when we used a guide tube that could influence the flow of air.

Abstract: An electron stimulated desorption (ESD) experimental system consisting of a ultrahigh vacuum chamber, micro channel plate, electron gun, quadrupole mass spectrometer, liquid helium and liquid nitrogen cryostat, and a gas supply tube etc., was set up and evaluated in order to investigate desorption particles at the surface of rare gas solids (RGS). Ar was deposited on the copper sample for 200 seconds at a pressure of 6.3 x 10–4 Pa. Ion currents from the RGS during bombardment at various electron gun energies were measured. These increased proportionally with filament currents between 1.5 A and 1.75 A. With the electron gun turned on, the dominant residual species in the vacuum chamber were H2O, H2, C, O, N2, Ar, and CO2, as measured using a quadrupole mass spectrometer (QMS). The H2O partial pressure was almost 50 % of the total pressure, and that of the other gas species were lower than 20 %. Before starting the experiments, the ultimate base pressure of the ultrahigh vacuum chamber reached 10–8 Pa.

Abstract: Outgassing, the evolution of gas from the material in a vacuum, is not only a source of micro contamination in a semiconductor or the flat display panel production process, but it also a limitation factor in the ultra clean process of nano-technology. The outgassing from the materials of satellites and spacecrafts must be controlled for increased safety and function because space is also a vacuum environment. Several methods are used in outgassing measurement in general, but there is no one method suitable for obtaining all outgassing data. The most suitable method for a particular application must be chosen by the experimenter or user. Three types of outgassing measurement systems were fabricated and characterized, ‘Throughput method,’ ‘Rate of Rise method’ and ‘Mass Loss Measurement method’. The outgassing rates of many kinds of materials were measured and characterized using these systems.