Plasma-Derived Low Temperature Ion Source

Focused ion beams (FIBs) employing a plasma ion source are employed in research and industrial applications, including nanotechnology, biotechnology, semiconductor manufacture, and energy exploration. Plasma ion beams of noble gases like argon, krypton, and xenon are of particular importance in preparation of samples for high-precision microscopy. Noble gas ions excel at this task because they are inert, and because they can rapidly remove large quantities of material. Despite these benefits, the current generation of plasma FIBs are not typically used in important tasks which require high-resolution, like circuit edit for semiconductor devices, because they lack the ability to be focused tightly. In this SBIR project, a new source of noble-gas ions will be developed that addresses limitations in commercially available plasma FIBs. This ion source will increase the precision of these instruments by 10x by reducing the focal spot size of the beam. It will retain all of the advantages of existing plasma ion sources, such as high material removal rates. The new ion source technology works by photoionizing laser- cooled atoms to create a bright beam that can be focused to a few-nm in size. In Phase I a laser-cooled argon beam was created and its properties analyzed. Measurement of this integrated flux and flux density indicate that it will achieve the project aims of 10x better precision when coupled to a FIB system. Follow-up research will focus on ionization and production of high-brightness ion beams with a current up to several nano-Amperes. In Phase II, an Ar+ ion source, based on the Phase I design, will be integrated with a FIB instrument. This prototype will be used to validate the noble gas FIB in key applications like transmission electron microscope sample preparation. Once complete, FIB instruments employing the new noble gas ion source will be ready for commercial deployment. These instruments will aid academic and commercial researchers in diverse set of fields such as biology, material science, radiometry, and semiconductor manufacture. Concretely, these efforts will enable or enhance the use of noble-gas ion beams in applications such as nanofabrication, and transmission electron microscopy, and atom probe tomography.