A method for improving the adhesion of an impermeable film on a porous low-k
dielectric
film in an interconnect structure is disclosed. The method provides an in-situ
annealing step before the deposition of the impermeable film to release the volatile
trapped molecules such as water, alcohol, HCl, and HF vapor, inside the pores of
the porous low-k dielectric film. The method also provides an in-situ deposition
step of the impermeable film right after the deposition of the porous low dielectric
film without exposure to an atmosphere containing trappable molecules. The method
further provides an in-situ deposition step of the impermeable film right after
the removal a portion of the porous low-k dielectric film without exposure to an
atmosphere containing trappable molecules. By the removal of all trapped molecules
inside the porous low-k dielectric film, the adhesion between the deposited impermeable
film and the low-k dielectric film is improved. This method is applicable to many
porous low-k dielectric films such as porous hydrosilsesquioxane or porous methyl
silsesquioxane, porous silica structures such as aerogel, low temperature deposited
silicon carbon films, low temperature deposited Si-O-C films and methyl doped porous silica.
