AAAR 32nd Annual Conference
September 30 - October 4, 2013
Oregon Convention Center
Portland, Oregon, USA
Abstract View
Correlation between Number Concentration of Generated Particles and Concentration of Airborne Molecular Contamination at Different Relative Humidity and Residence Time under Soft X-ray Irradiation
CHANG HYUK KIM, Zhili Zuo, Hartmut Finger, Stefan Haep, Heinz Fissan, David Y. H. Pui, University of Minnesota
Abstract Number: 261 Working Group: Control Technology
Abstract Most of the problems caused by particulate contaminations in semiconductor industry have been solved by the development of filtration systems during the last couple of decades. However, particle generation induced by airborne molecular contamination (AMC) is still an important issue. As the manufacturing technology has been improved to make semiconductor devices with smaller feature sizes, nanoparticles and haze can be generated from AMC at very low concentration levels (several ppb or ppt) under high energy irradiation, which increase manufacturing cost by destroying photo masks and reducing products yields. Therefore, it is important to understand the mechanism for the radiation induced particle formation from AMC to prevent the increase of manufacturing cost.
The objectives of this study were to determine the correlation between number concentration of generated particles and concentration of AMC at different relative humidity (RH) and residence time under irradiation and to evaluate an AMC filter performance by measuring AMC concentration based on this correlation. Two major AMCs, ammonia and sulfuric dioxide were diluted with nitrogen gas to achieve concentrations down to a few ppb levels and then introduced to a reaction chamber at different flow rates and RH, where AMCs were converted into particles. Soft X-ray was used to accelerate the gas-to-particle conversion. The resulting number concentration and size distribution of particles were measured by a condensation particle counter and a scanning mobility particle sizer, respectively. The particle number concentration and AMC concentration showed a power-law relationship at different residence time. Results from tests at different relative humidity suggest that water is one of the important reaction components for particle formation and the amount of water needed to generate particles depends on the AMC concentration. AMC concentrations before and after the filtration were detected and compared to evaluate the filter performance based on these results.