Development of the ERC cold-cathode ion source for use on the PR-30 ion-implantation system

Abstract

The ERC cold‐cathode ion source has been in routine production use on several PR‐30 systems for the past three years. This source has been further developed to improve target current, lifetime, and stability. The ion‐optical lens has been changed from circular to elliptical geometry in order to provide an asymmetric beam for entry into the PR‐30 analyzing magnet. This measure, as well as the use of higher extraction voltages, provides higher beam currents on the PR‐30 target wafers. Beam steering in the nondispersive direction has been provided to correct the effects of minor machine misalignments, further enhancing target current. The discharge chamber has been modified to increase source lifetime. A new gas‐feed control system and a new method of oven temperature control have been devised to provide good source and ion beam stability. The source operates with only occasional attention by unskilled personnel, and has been used principally for boron and arsenic implants. Target currents of 1‐mA boron and 4‐mA arsenic can be obtained routinely. Lifetimes are of the order of 40–80 h, depending on ion species. The source has also been used to provide 5‐mA phosphorus, 4‐mA argon, 3‐mA helium and neon, and 0.3‐mA nickel and palladiumion beams.