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Research Abstracts Online
January 2008 - March 2009

University of Minnesota Twin Cities
Institute of Technology
Department of Mechanical Engineering

PI: David Y. H. Pui, Associate Fellow

Numerical Investigation of Nanoparticle Contamination, Deposition, and Separation in Semiconductor Manufacturing, Air Filtration, and Human Health

These researchers are currently involved in several projects involving particles and filtration. One involves extreme ultraviolet lithography (EUVL), a strong candidate for the next generation lithography for manufacturing integrated circuits of feature size down to 30 nm and beyond. One of the most crucial challenges for EUVL technology is the prevention of particle contamination on EUVL masks. Since conventional pellicles cannot be used to protect the EUVL mask, it is therefore necessary to develop new protection schemes to prevent the contamination of EUVL masks in all stages of handling, storage, and shipping. The researchers are performing numerical simulations to investigate deposition of very small particles on EUVL masks as part of this research.

A second project uses numerical simulation to investigate filtration of aerosol particles by fibrous filters. They have developed a numerical model composed of a layer of nanofibers and a porous medium that simulates a substrate. Results from this model are in good agreement with experimental data.

The third project investigates the cone-jet mode in a dual-capillary electrospraying system. This mode is especially valuable for practical applications because of its ability to produce highly charged, monodispersed capsules. The researchers are developing a model that will help them study the establishment and operation envelope of the cone-jet mode operation, which is useful in understanding the mechanisms involved.

In a final project, the researchers have developed a web-based software for filter performance evaluation. The software allows users to specify filtration parameters including the challenging particle properties, face velocity, pressure, temperature, fiber size, filter solidity and thickness, etc. The software then calculates the filtration efficiency and pressure drop and displays the results almost instantaneously. A wide range of fiber sizes, down to the nanometer range, is covered by the software. Experimental data and numerical simulation data obtained using MSI computing resources were utilized to validate the software. The software was posted on website and made available to the members of the Center of Filtration Research in Nov 2008. There have been many positive responses and the researchers expect that the software will be used extensively in filter design and optimization.

Group Members

Christof Asbach, Institut für Energie- und Umwelttechnik (IUTA), Duisburg, Germany
Da-Ren Chen, Department of Energy, Environmental, and Chemical Engineering, Washington University in St. Louis, St. Louis, Missouri
Seong Chan Kim, Research Associate
Tsz Yan Ling, Graduate Student
Chaolong Qi, Research Associate
Weon Shin, Graduate Student
Jimmy Jing Wang, Research Associate