Investigation of Various GeF4 Gas Mixtures for Improvement of Germanium Ion Implantation

Germanium implant is commonly used in advanced semiconductor device manufacturing as one of the major material modification steps. Germanium Tetrafluoride (GeF ₄ ) is almost exclusively used as the primary source gas and its impact on ion source performance (poor source lifetime due to fluorine-induced halogen cycle) is well known. Our previous studies have demonstrated that mixing GeF ₄ with hydrogen (H ₂ ) can reduce the halogen cycle impact and prolong the source life as well as increase the beam current [1, 2]. In this work, we further investigated GeF ₄ mixed with other candidates such as inert, hydride and fluorohydride gases (e.g. Xe, N ₂ , GeH ₄ and CH ₃ F). Ge ⁺ beam current performance and source effects were examined and compared with pure GeF ₄ and previously reported GeF ₄ /H ₂ mixtures.