Incorporating thin films with low dielectric constants (k<2.8) in microelectronic devices would increase the speed of transistors and lower power consumption. Speed and power consumption depends on the RC (Resistance-Capacitance) delay of the circuit. Replacing silicon dioxide dielectrics with a material having a lower k value will reduce the capacitance of the circuits. One approach to lower the k value is to introduce pores filled with air (k=1), which decreases the overall dielectric constant of the film. There are processing challenges associated with integration of porous films. One hurdle to overcome is the creation of damage sites by plasma etching and ashing during pattern formation. The damage sites contain polarizable silanol (SiO-H) groups, which increase the k value. Film repair was accomplished by reacting chlorosilane molecules with silanol groups. The chlorosilanes were transported into the damaged nanoporous matrix using supercritical CO2 (scCO2). Methylsilsesquioxane (MSQ) films were studied where the dielectric constant is 2.4 and contact angle above 100¢ª for the as deposited material and k=3.5 and contact angle <15¢ª after etching and ashing. Repair using trimethylchlorosilane (TMCS) and methyltrichloroslane (MTCS) at 80-150 bar and 30-60¢ªC for 3-20 min reduced the k value to 2.5±0.1 based on capacitance-voltage measurements of capacitor dots fabricated in the lab. Contact angles >80°Æ confirmed the restoration of the hydrophobicity of the surface. Sylilation formed a protective layer over the surface of the nanoporous film as shown by ellipsometry. This layer can be controlled by concentration and processing conditions.