Stability of fluorinated parylenes to oxygen reactive-ion etching under aluminum, aluminum oxide, and tantalum nitride overlayers
The fluorine stability of two parylenes, aliphatic-fluorinated AF-4 (α, α, α′, α′ poly(p-tetrafluoroxylylene) and aromatic-fluorinated VT-4 (2, 3, 5, 6 poly(p-tetrafluoroxylylene), were investigated underneath Al, Al2O3, and TaNX overlayers with and without exposure to oxygen reactive-ion etching (RIE). No fluorine diffusion was observed for Al films deposited onto the as-received parylenes. However, after oxygen RIE, x-ray photoelectron spectroscopy (XPS) depth profiling detected fluorine diffusion throughout Al and to a lesser extent Al2O3 but in contrast to Ta2.67N. Metal-fluoride bonding was evident at the metal/parylene interface for all the overlayers after the parylene was exposed to oxygen RIE and annealed.