Pump Down Tests and Applications of an Ultra High Vacuum System
Date Issued
2009
Date
2009
Author(s)
Chen, Tzu-Yang
Abstract
This paper studies the pump down tests and applications of an ultra high vacuum (UHV) system for electron-beam direct-write lithography. The UHV system includes a vacuum chamber, an oil vane pump, a turbo molecular pump, an ion pump, a low vacuum gauge, a high vacuum gauge, and a baking heater fitted around the chamber. The prototype of the vacuum system is manufactured and performances of the prototype are tested. In order to reach different specified vacuum pressure within the shortest time, effects of the different operating process combinations are tested and analyzed. Main factors affecting the pump down characteristics include effect of ion pump, baking temperature, and baking periods. The oil vane pump and the turbo pump are always turned on during the entire pump down tests. From the test results of different operating process combinations, it shows that the vacuum system can reach the lowest vacuum pressure of 1.3E-9 Torr within 7 days, with turned on ion pump and baking of chamber for 5 days. It also shows that the chamber can reach the vacuum pressure to 9.7E-9 Torr within 1 day with turned on ion pump and one baking period. It is also concluded that both the pump down time and vacuum pressure can be greatly reduced with the adding of baking process. Finally, a field emission test of a 4x4 silicon tip array is carried out successfully inside the UHV chamber under the constant applied voltage of 1200V for test duration of 2 hours. With the field emission test species inside the chamber, the vacuum pressure reaches the order of 1.0E-7 Torr within 1 hour.
Subjects
ultra high vacuum system
e-beam lithography
vacuum baking
pump down test
field emission
Type
thesis
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