A study on wafer-handling robot with coaxial twin-shaft magnetic fluid seals

Abstract

Wafer-handling robot is an important IC equipment in wafer manufacturing system. As such robot works in vacuum environment, there is a high requirement for the sealing device of it. Magnetic fluid rotary seal shows the effectiveness in machinery operating in a vacuum chamber, and the advantages of simple design, low friction and zero leakage at almost any rotation speed. This paper deduces the seal differential pressure formulas for magnetic fluid rotary seals. A coaxial twin-shaft magnetic fluid seals for wafer-handling robot is designed, of which the important structure parameters are optimized, the magnetic flux density distribution in the sealing gaps is analyzed and the pressure resistance of inner and outer shaft is calculated. Finally, a wafer-handling robot equipped with coaxial twin-shaft magnetic fluid rotary seals and bellows seal is devised. It is shown that this kind of robot can enhance the grade of vacuum and cleanliness in wafer processing system. © 2009 Springer-Verlag Berlin Heidelberg.