Development of a Negative He ion source with Non-Metallic Charge Exchange

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We propose to investigate the production of a negatively-charged He ion beam (10 keV to 30 keV) via charge exchange through non-metallic molecular vapours or condensed matter. Existing negative He ion sources pass He+ ions through a vapour of alkali metal that readily ionize, transferring electrons with a 1-2 % efficiency. However, a side effect of this process is that the desired beam of He- ion becomes contaminated with alkali metal ions. Since one of the major users of ion accelerators is the semiconductor industry, an efficient charge exchange alternative to alkali metals for semiconductor implantation is highly desired. There are numerous molecular compounds that have similar or lower ionization energies to those of alkali metals (~ 6 eV). We also have many possible materials in thin film form that could potentially act as an efficient ion exchange medium, including simply amorphous carbon, multilayer graphene or hexagonal boron nitride (h-BN). The industrial collaborator, D-Pace Inc., Nelson BC, is a globally-recognized innovator in ion source design and manufacture. They have designed and marketed a novel, negative hydrogen ion source through modifications of licensed technology from TRIUMF. They have an established ion source test laboratory that will be used in this project to carry out ion exchange experiments on molecular vapour sources. At SFU a focussed He ion microscope (HIM) facility will be used to measure the percentage charge exchange, after passing through thin layers of condensed matter. If an efficient source can be found, D-Pace will move forward to develop a product that they will offer to the ion implantation industry. The project will strengthen the capabilities of a Canadian manufacturing company, provide critical training of HQP of all levels, as well as generate new knowledge important to global semiconductor science and technology.