Fourier transform infrared characterization of moisture absorption in SiOFfilms

In this paper, the water absorption characteristics of as-deposited and ann ealed liquid-phase-deposited fluorinated silicon oxide (LPD-SiOF) films wer e investigated to clarify the film properties. The stability of moisture ab sorption was characterized under an air-exposure environment of 23 degrees C and 65% humidity. The as-deposited LPD-SiOF film was found to easily abso rb moisture from air and therefore to become unstable in terms of the diele ctric property. To obtain a highly stable dielectric film, a hydrofluosilic ic acid concentration of 2.2 M (with the corresponding fluorine content of 4.9 at.%) is suggested because it has a minimum water absorption chang (<3% ). The related OH concentration was comparable (or even smaller) to those o f other SiOF films grown by chemical vapor deposition. Moreover, high-tempe rature annealing in nitrogen ambient was utilized to drive out the moisture absorbed in an LPD-SiOF film. The annealing process after deposition tends to render the Trim surface hydrophobic. The resulting OH bonds were found to disappear after annealing and did not reappear even after long time of a ir exposure.