Operating experience with the Helios compact storage ring at IBM

Abstract

Helios is a compact, superconducting storage ring designed and manufactured by Oxford Instruments specifically for use as an X-ray source for lithography. The ring, which runs at 686 MeV and has a critical wavelength of λc = 9 A ̊, uses a 200 MeV linac for injection. The ring was delivered to the IBM Advanced Lithography Facility in East Fishkill, New York in the spring of 1991 and has been in routine use since the beginning of 1992. Its performance has been characterized from both technical (beam size, lifetime, etc.) and functional (reliability, ease of use, etc.) standpoints. The specifications for the storage ring are reviewed with an emphasis on their relation to lithographic requirements. The ring has met and in some cases significantly exceeded the original specifications, having an average stored current of ∼ 165 mA with a 1/e lifetime of ∼ 20 hours at a current of 200 mA. Re-injection typically takes 15-20 min. Beam has been available more than 95% of the scheduled time since January 1992, which is particularly significant for a tool considered for use in a manufacturing application. This paper discusses the operating history of the ring, describing the improvements that have been achieved in such areas as beam lifetime, reliability, and injection, including the commissioning of a low energy (90 MeV) injection mode. The present performance of the ring is also summarized. © 1994.