Porous methylsilsesquioxane (p-MSQ) films (JSR LKD 5109) were treated with
alkyldimethylmonochlorosilanes having chain lengths of one, four, and eight
carbon atoms dissolved in supercritical carbon dioxide at 150-300 atm and
50-60°C to repair oxygen ashing damage. Fourier transform infrared (FTIR)
spectroscopy showed that trimethylchlorosilane (TMCS),
butyldimethylchlorosilane (BDMCS), and octyldimethylchlorosilane (ODMCS)
reacted with silanol groups on the surfaces of the pores producing covalent
Si-O-Si bonds. Selfcondensation between alkylsilanols produced a residue on
the surface, which was partially removed using a pure scCO2
rinse. The hydrophobicity of the blanket p-MSQ surface was recovered after
silylation treatment as shown by contact angles >85°. The initial
dielectric constant of 2.4 ± 0.1 increased to 3.5 ± 0.1 after oxygen plasma
ashing and was reduced to 2.6 ± 0.1 by TMCS, 2.8 ± 0.1 by BDMCS, and 3.2 by
ODMCS.