微小環境潔淨室流場及污染源控制分析

Abstract

對於半導體工業生產環境的嚴格要求，封閉製程空間概念則為另一種值得考量可行的方法。基於此種概念的微小環境潔淨室，可以對積體電路產業界，提供比傳統潔淨室更為妥善的製程環境，且更具彈性及省去不少操作和成本的花費。 本文利用STAR-CD套裝軟體，來研究微小環境潔淨室內的流場和污染源控制。基於有限容積法，探討三維空間的微小環境潔淨室，並指出空氣速度、壓力分佈和粒子軌跡等結果，以做為新設計改變的依據。期望使新的微小環境潔淨室設計，能夠具有增強微小環境潔淨室效率的氣流。特別是能改善製程中會聚集粒子的迴流區域，且可常保持與外界正壓差的狀態，以預防污染物的進入。 研究結果顯示，微小環境潔淨室可藉由入口氣流速度值的強弱，控制危險氣體之污染區域範圍。亦在工作平台上加入適當數量的回風孔及改變入口氣流方向，可以分別解決需在室內擺設工作平台及發熱工作機台的問題。而不同大小的微塵粒子在相同流場中之運動軌跡也不同。

The application of minienvironment clean room (MCR) to resolve long-standing particulate control issues in the clean room performance and added flexibility has rapidly gained momentum in the last ten years. The goals of MCR were to reduce airborne particles, isolates the clean room personnel from the product, and use airflow in the mini-environment to reduce equipment-generated particles. The objective of this research is to study the flow field and contaminative source control in MCR by the computer software STAR-CD. The three-dimensional code used to predict the air velocity, pressure distribution and the particle traces in the MCR based on a finite volume approach. The results prompted a design change. The new design is shown to have a desirable airflow for a more effective MCR performance. Particular attention was paid to air re-circulation zones that could potentially trap particles generated during the process and to maintaining a positive differential pressure to prevent cross contaimination.