Humidity Control for Front Opening Unified Pod after Opening Its Door in a Mini-Environment

Shih-Cheng Hu,Ben-Ran Fu,Tee Lin,Zhe-Wei Li

doi:10.3390/app8071149

Shih-Cheng Hu, Ben-Ran Fu + Show 2 more

Open Access

https://doi.org/10.3390/app8071149

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Abstract

Wafers are usually placed in a front opening unified pod (FOUP) while waiting in the line of manufacturing processes; a conventional way for preventing (or removing) contamination is to purge an FOUP with a gas, so as to maintain the cleanliness level. This study investigates the effect of the flow rate of clean dry air (CDA), supplied to the purge system and air curtain, on the moisture prevention performance, while opening the FOUP door in a mini-environment. An initial relative humidity (RH) in the pre-purged FOUP was approximately 0%, whereas an RH in the mini-environment was about 43%. Conventional, diffuser, and panel purge approaches were tested. The results showed that the moisture in the surroundings rapidly entered the FOUP when the door was opened, without using either the purge system or air curtain. When the CDA was then supplied to both the purge system and the air curtain, the RH values decreased significantly; the drop slope of the RH for the diffuser- and panel-purge processes was much larger than that of the conventional-purge process. In addition, the moisture prevention performance when the developed panel-purge system was used was slightly lower than when using the diffuser-purge system. However, the use of the panel-purge method could sufficiently suppress the vibration problem. In the present study, the case with CDA flow rates of 150 L/min to the air curtain and 250 L/min to the panel-purge device had the best moisture prevention performance, because of the smallest values for both the mean and maximum RH values (i.e., 1.3% and 9.5%, respectively) in the FOUP.

Highlights

In recent decades, the semiconductor and optoelectronics industries have become important contributors to Taiwan’s economic development
The results indicated that the use of the air curtain with the clean dry air (CDA) flow rate of 220 L/min, at a given in the front opening unified pod (FOUP) at less than 10% during the FOUP door opening in the mini-environment, which might
This study investigates the effect of the CDA flow rate, supplied to the purge system and air curtain, on the moisture prevention when the FOUP door was opened in a mini-environment

Summary

Introduction

The semiconductor and optoelectronics industries have become important contributors to Taiwan’s economic development. When a FOUP door is opened, additional methods are generally used to prevent outside contamination (such as moisture, oxygen, and particles) from entering the FOUP, for example, Keyhani et al [15] employed an air curtain to meet this goal. The use of diffusers in a FOUP while purging can efficiently prevent or remove the contamination from when its door is opened or closed, a higher purging flow 3rate. The present study investigates theand effect of the CDA flow rate, supplied the purgethat, system and induce particle contamination vibration problems It should to be mentioned if the vibration of the FOUP or wafers isperformance too strong, wafer breakage could the occur, especially a wafer air curtain, on the moisture prevention while opening door.forTo reduce any already we fabricated patterns.

Procedures for for LPU

Schematic

Results and Discussion

Conclusions