Design Concept of a New Secondary Ion Optics System for Use with Quadrupole Mass Spectrometers

Abstract

Most commercially available SIMS optics systems for use with quadrupole mass spectrometers suffer from the problems caused by mixing the parameters governing secondary ion emission with those related to the ion injection into the mass filter. In this paper, we propose a system which overcomes these difficulties. They have been partly solved by a previous design used for a dedicated SIMS instrument, which therefore has been a guideline for the present work. Because of the intended use in combination with XPS, this instrument is required to have a very large lateral acceptance of 10 mm diameter. In experiments where static conditions must be applied, this large acceptance allows reduced current density at a given sensitivity. On the other hand, in depth profiling the detection limits are improved at a given erosion Late. Additional requirements to be met have been energy filtering and reduction of the quadrupole mass discriminating effects. k detailed discussion of this system and its performance will be published elsewhere.