A micromachined electron beam ion source

This paper presents the concept, the manufacturing details and the results of a micromachined ion source with the dimensions of only a few cubic milli meters. Since by scaling down a vacuum system the pressure increases at a c onstant Knudsen number. Usually filaments are used to generate electrons fo r electron beam ion sources. When the operation pressure increases to low v acuum the lifetime of a filament decreases unacceptably. For this reason, t he ionising electrons are provided by a microwave-stimulated plasma. The ai m of this concept is not only to scale down a macroscopic system but also t o take advantage of the added features of a microsystem. Due to the electro n source, the system operates at a relatively high pressure of about a few pascals, which principally simplifies the peripheral pumping system. The de sign of the ion source and its components are optimised with a simulation s oftware tool. A technology known as the 'poor men's LIGA,' using the Epon S U-8 resist, is introduced into the manufacturing process. It eases the manu facturing of even complex microsystems. The complete system operates at a p ressure of 100 Pa and the extractable ion current is about a few microamper es. (C) 2000 Elsevier Science S.A. All rights reserved.