AbstractConventional ash strippers can easily damage most porous low-k materials, causing increased dielectric constants and decreased film thicknesses. This effect is more prominent in carbon containing porous low-k materials such as methylsilsesquioxane (MSQ). Ashed MSQ films exhibit increased water adsorption and dielectric constants due to the removal of methyl groups and structural damage caused by interaction with plasma species. Supercritical carbon dioxide (SC-CO2), has attracted considerable attention due its low cost, low critical point temperatures and pressures, and environmentally benign nature. This work describes the effects of SC-CO2 in combination with silylating agents on O2 ash-damaged MSQ films. FTIR, sessiledrop goniometric contact angle measurements, and SEM were used to monitor changes in the films' chemical bonding, composition, and microstructure.