Experimental Study on the Moisture Control in Wafer Carrier

• Main Authors: Chun-Yong Khoo 邱俊榮, 邱俊榮
• Other Authors: Shih-Cheng Hu 胡石政
• Format: Others
• Language: en_US
• Published: 2014
• Online Access: http://ndltd.ncl.edu.tw/handle/9swt7k

博士 === 國立臺北科技大學 === 冷凍空調工程系所 === 102 === This study is designated to experimentally determine the effect of varied clean dry air (CDA) purging rate on the alteration rate of moisture content inside an alpha version of 450 mm polycarbonate (PC) Front Opening Unified Pod (FOUP), and to investigate the prospect of liquid crystal polymer (LCP) as a new, alternative base material for 300 mm FOUP. The 450 mm PC FOUP which fully loaded with 25 pieces of dummy wafers was purged for 30 minutes with the varied CDA purging rates range of 30~360 L/min (LPM) via the two rear inlet ports. The decay of moisture in the FOUP was measured in situ using temperature and humidity data loggers and was analyzed. Moisture content less than 5% relative humidity within the FOUP ambient was served as key evaluation factor. The results showed that higher purging rate of CDA demonstrates favorable moisture depletion rate within the gaps formed between wafers, i.e. 150 LPM and 180 LPM cases. The middle zone (wafer slot 13) was the spot that the purge air difficult to reach. The convection of purging gas is the dominant mode of mass transfer in the early stage of the purging process, and later replaced by the diffusion of purging gas into the tiny spaces between wafer slots. Meanwhile, with the similar settings and requirement, the moisture depletion in the alpha version LCP FOUP, the commercial 300 mm PC FOUP, and the commercial Barrier FOUP were examined but with the varied CDA purging rates range of 15~105 L/min (LPM). Different base material of 300 mm FOUP does show significant effects on purging efficiency. The 300 mm barrier FOUP presents fast moisture decay rates within short times but vice versa for 300 mm PC FOUP. The 300 mm LCP FOUP demonstrates the promising moisture decay rates that are highly comparative to the results of Barrier FOUP, although slightly more time was required to reach the threshold limit of 5% RH when the FOUP was fully loaded.