Why can fluorine clean faster than other fluorinated gases?
Fluorine is the simplest molecule containing fluorine atoms, and it is these atoms you want to be delivering to the process chamber for cleaning or etching. The bond strength of F-F is much lower than any other F-bond and thus much less energy is required to create F atoms or radicals than if F is bonded to any other element. This means that for a given process chamber configuration, to deliver the same number of fluorine atoms / radicals as any other gas, lower power or temperature is required. Obviously this opens up a greater process window and tests have shown that the same RPS generator can deliver up to 5x more fluorine than NF3 which enables up to 3x faster cleaning.