Carbon Implantation Performance Improvement by Mixing Carbon Monoxide (CO) with Carbonyl Fluoride (COF2) and Carbon Dioxide (CO2)

Co-implantation of impurities such as carbon (C) has been proven to effectively reduce Transient Enhanced Diffusion (TED) of boron during annealing, enabling the formation of high-quality ultra-shallow junctions - a requirement for advanced-node semiconductor devices. Carbon dioxide (CO₂) is traditionally used as the feed gas in implant tools for carbon implantation. Recently, carbon monoxide (CO) has been widely adopted as a replacement to CO₂ due to its lower oxygen content. To further improve the carbon implant performance, a mixture of CO, carbonyl fluoride (COF₂), and CO₂ is studied and reported in this paper. The effects of the additional fluorine and extra oxygen content from COF₂ or CO₂ are investigated. Our experiments show that with the right balance and mixture level of COF₂ and CO₂, the carbon mixture can achieve improvements in key implant tool performance parameters, such as beam current and source life. Additionally, the CO/COF₂/CO₂ mixture stability is studied, and a safe delivery package is described.