Host: Farhang Shadman, Chemical and Environmental Engineering, University of Arizona
Presented by: Jivaan Kishore Jhothiraman, Chemical and Environmental Engineering, University of Arizona
Topic title: "Application of PCP in drying down UHP gas distribution systems and tools"
Abstract: Presence of trace contaminants in process fluids is highly detrimental to the manufacture of high performance semiconductor devices. Gas distribution systems transporting ultra-high purity gas from bulk storage to the point of use are susceptible to contaminants owing to the interactions with the EPSS surface. This necessitates frequent purging of the distribution lines to meet the stringent restrictions placed at the point of use in current fabrication processes. Process throughput and economy of high volume manufacturing processes is severely affected by the high amount of UHP gas and process downtime involved with such purging operations. Current work focusses on application of PCP on purging of gas distribution networks and process tools.
A combinatorial approach involving experimental investigation and process simulation is used to analyze the effect of operational and geometrical parameters affecting contaminant propagation. The process simulator predictions are validated using data from an experimental test bed using moisture as the model contaminant. The application of cyclic purge on dead volumes in gas distribution systems and process tools with varying number and sizes of dead volumes and is studied. The advantages of pressure cyclic purge over conventional purge is presented in terms of savings in purge time and purge gas usage in order to realize a certain purity baseline, along with system parameters for which this advantage can be realized. Key cycling parameters such as frequency, ratio of pressurization to depressurization times, pressure ranges and PCP sequences are identified for effective contaminant removal.