We have suggested methylating chemicals to repair plasma damaged low-k films. Methylating chemicals, dimethyl carbonate (DMC) and dipivaloyl methane (DPM), were designed to supply CH3 molecules inside the damaged films. The repairing treatments improved hydrophobicity inside damaged low-k films by the formation of CH3 and OCH3 groups. As a result, electric properties were improved by the repairing treatments.