boron trifluoride (BF₃)

Boron Trifluoride is a commonly used gas for Ion Implantation of the P–type dopant Boron where shallow doping concentration profiles are required. Enriched Boron-11 is also available.  
Ion implantation is a process by which ionized atoms are accelerated directly into a substrate to selectively add dopant atoms. The gases used for this processing operation must be exceptionally pure to prevent unwanted chemical reactions. Dopant ions, such as BF₂⁺, can be selected by mass filter in ion implanters to required doping profiles. Typically, dopant is activated in a rapid thermal annealing process.