Yoo S.-K.,WITHTECH INC. Co. |
Shiue A.,National Taipei University of Technology |
Lee T.-S.,National Taipei University of Technology |
Hu S.-C.,National Taipei University of Technology |
And 2 more authors.
Advanced Science Letters | Year: 2012
Front Opening Unified Pod (FOUP), a wafer carrier, is used for storage and transportation of wafers to prevent contamination caused by external exposure. Airborne molecular contaminants (AMCs) are a common cause of certain defects and pattern failures in chip manufacturing. A useful method for reducing these yield-affecting influences is purging the FOUP surface with nitrogen gas. Ammonia is by far the most commonly found AMC due to its presence in process chemicals. The purging procedure of the FOUP was examined by continuous measurement of ammonia in the purging gas flow. The level of contamination caused by ammonia was controlled by diffusion of NH3 from NH4OH solution. The effect of concentration and exposure time of contaminant was monitored by a highly sensitive ammonia monitoring system. The results showed that ammonia concentration has a more significant effect than exposure time on the time required to purge down the ammonia level inside a FOUP. The exposure time did not significantly change the efficiency of cleaning contamination inside the FOUP. It was observed that prolonged purging (more than 12 hours) was required to get less than 2 ppbv, depending on the contamination level. © 2012 American Scientific Publishers. All rights reserved. Source
Song G.J.,SK hynix |
Hwang S.M.,SK hynix |
Koo S.J.,SK hynix |
Kim H.R.,SK hynix |
And 9 more authors.
Aerosol and Air Quality Research | Year: 2015
We have investigated the hindrance to the deposition growth of silicon nitride (SiN) passivation layer from the contamination by airborne molecules in the front opening unified pod (FOUP). In particular, an artificial contamination of FOUP by fluoride ions as the source of the contaminants is utilized to elucidate the influence of contamination on the wafer surface. When the bare wafer surface is exposed to fluoride ions in the contaminated FOUP, the deposited thickness of the SiN layer is observed to decrease to a maximum of 11 Å from our experimental condition. On the other hand, there is no appreciable variation in the thickness of deposited SiN layer stored in the pre-cleaned FOUP. Based on the analytical results of wafer surfaces and FOUPs, we believe that the contamination of fluoride ions on wafer surfaces is originated from the contaminated surface of FOUP. Therefore, we conclude that it is necessary to clean and monitor the inside of FOUP on a regular basis, especially after wet or dry etching processes, which generates gaseous impurities. © Taiwan Association for Aerosol Research. Source