Design of a new ultra-high vacuum system for massively parallel maskless lithography

This paper designs a new ultra-high vacuum (UHV) system for electron-beam based massively parallel maskless lithography. The new UHV system consists of two parts. The main part includes main vacuum chamber and inner wafer holder. Another part includes transfer vacuum chamber and exchange rod which is used for transferring a 4-inch wafer. The design goal is to reach the high vacuum pressure within the shortest pumping down time to enhance electron-beam lithography operation efficiency. The major factors influencing the pumping down time in UHV system are the volume size and the different operation procedure. In the vacuum pump-down test, different operation procedures are examined to reach the required minimum vacuum pressure. The lowest vacuum pressure of the new UHV system reaches to the order 1.0E-9 Torr within 48 hours. The pumping down curve proves the new UHV system is a low-cost design and satisfies the design requirements.