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

我们建议调查生产的负电荷的He离子束（10千电子伏至30千电子伏）通过电荷交换通过非金属分子蒸气或凝聚态物质。现有的负He离子源使He+离子通过碱金属蒸气，该碱金属蒸气容易蒸发，以1- 2%的效率转移电子。然而，该过程的副作用是所需的He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，因此高度期望用于半导体注入的碱金属的有效电荷交换替代物。有许多分子化合物具有与碱金属类似或更低的电离能（约6 eV）。我们也有许多可能的薄膜形式的材料，可以潜在地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）。工业合作者D-Pace Inc.纳尔逊不列颠哥伦比亚省，是一个全球公认的创新的离子源设计和制造。他们通过修改TRIUMF的许可技术，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，将在本项目中用于对分子蒸汽源进行离子交换实验。在SFU，聚焦He离子显微镜（HIM）设施将用于测量通过凝聚态物质薄层后的电荷交换百分比。如果能找到一个有效的来源，D-Pace将继续开发一种产品，他们将提供给离子注入行业。该项目将加强加拿大制造公司的能力，为各级HQP提供关键培训，并产生对全球半导体科学和技术至关重要的新知识。

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.