XPS characterization of the interface between low dielectric constant amorphous fluoropolymer film and evaporation-deposited aluminum

The interaction of low dielectric constant amorphous fluoropolymer (AF) fil m with evaporation-deposited aluminum has been investigated via high-resolu tion X-ray photoelectron spectroscopy (XPS). For the sake of gaining the in terface of the AV AF sample, the partial aluminum has been removed by Ar io n etching. In situ XPS measurements show that Al fluoride, C-O-Al and Al ca rbide are formed at the interface between aluminum and AE The formation of Al fluoride results mainly from a reaction between Al atom and F free radic als due to the breakage of one C-F bond in CF3 groups, meanwhile, this also leads to an increase in CF2 groups. After annealing, the relative content of C-F bonds at the interface decreases remarkably, and the relative concen trations of C-O-Al and Al-C complexes increase evidently. However, the rela tive percentage of Al fluoride decreases, indicating that Al fluoride has h igher fluidity than the C-O-Al and AI-C complexes against annealing. Moreov er, the relative percentages of the elements at the interface show that the annealing causes a little diffusion of Al into the AF film. Possible react ion mechanisms of Al with AF are also discussed. (C) 2001 Published by Else vier Science B.V.