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

我们建议研究通过非金属分子蒸气或凝聚态物质的电荷交换产生带负电荷的He离子束(10keV到30keV)。现有的负氦离子源通过易于电离的碱金属蒸气传递He+离子，以1-2%的效率传递电子。然而，这一过程的一个副作用是，所需的氦离子束被碱金属离子污染。由于离子加速器的主要用户之一是半导体工业，因此人们非常希望有一种高效的电荷交换替代碱金属用于半导体注入。有许多分子化合物的电离能与碱金属的电离能相似或更低(~6 eV)。我们也有许多可能的薄膜材料，可以作为一种有效的离子交换介质，包括简单的无定形碳、多层石墨烯或六方氮化硼(h-BN)。工业合作伙伴D-PACE Inc.，Nelson BC，是全球公认的离子源设计和制造创新者。他们通过对TRIUMF许可技术的修改，设计并销售了一种新型的负氢离子源。他们有一个已建立的离子源测试实验室，将在该项目中用于对分子蒸汽源进行离子交换实验。在SFU，将使用聚焦离子显微镜(HIM)设备来测量穿过凝聚态物质薄层后的电荷交换百分比。如果能找到有效的来源，D-PACE将继续开发一种他们将提供给离子注入行业的产品。该项目将加强一家加拿大制造公司的能力，提供各级HQP的关键培训，并产生对全球半导体科学和技术重要的新知识。

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.