Design and Analysis of Ultra-high Vacuum Systems
Date Issued
2009
Date
2009
Author(s)
Yang, Chieh-Jen
Abstract
This paper studies the design and analysis of ultra-high vacuum (UHV) systems for massively parallel maskless electron-beam direct-write lithography. The inner pressure of main vacuum chamber is designed to keep to the order of 1.0E-9 Torr. A low cost ultra-high vacuum system design is proposed, and the main components include vacuum chambers, vacuum pumps, and vacuum gauges. To achieve the UHV in the chamber, three different types of vacuum pumps are used: a rotary vane pump, a turbo molecular pump and an ion pump. The main chamber is made up of stainless steel, and its volume is about 13 litters. A parametric 3D modeling program is developed for automatically generating 3D solid model of the chamber structure. In order to get more accurate prediction of the pump down curve of the vacuum system, the vacuum pressure versus time curve for the vacuum chamber is analyzed based on basic vacuum theories. According to the initial single chamber design, a two-chamber design is also proposed for easy transfer of test samples between the main chamber and the load-lock chamber. In addition, an apparatus for transferring the wafer is designed to lock and release the wafer inside the main chamber by operation of an exchange rod. The prototype of the single UHV chamber system is manufactured and performances of the prototype are measured. From the measured results, it shows that the predicted pump down curve is quite in agreement with the measured pump down curve. The vacuum chamber can reach to the lowest vacuum pressure of 1.3E-9 Torr within 7 days by applying a 5-day baking.
Subjects
ultra-high vacuum system
vacuum chamber
load-lock chamber
vacuum pump
apparatus for transferring the wafer
Type
thesis
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