The present invention makes it possible to provide a semiconductor element cleaning method that is characterized in that: a hard mask pattern is formed on a substrate that has a low relative permittivity film and at least one of a cobalt, a cobalt alloy, or a tungsten plug; and a cleaning liquid that contains 0.001-20% by mass of an alkali metallic compound, 0.1-30% by mass of quaternary ammonium hydroxide, 0.01-60% by mass of a organic water-soluble solvent, 0.0001-0.1% by mass of hydrogen peroxide, and water is subsequently used on a semiconductor element in which, using the hard mask pattern as a mask, the hard mask, the low relative permittivity film, and a barrier insulating film are dry etched, and dry etch residues are removed.

A method for cleaning etch residues that may include treating an etched surface with an aqueous lanthanoid solution, wherein the aqueous lanthanoid solution removes an etch residue that includes a majority of hydrocarbons and at least one element selected from the group consisting of carbon, oxygen, fluorine, nitrogen and silicon. In one example, the aqueous solution may be cerium ammonium nitrate (Ce(NH.sub.4)(NO.sub.3)),(CAN).

Cleaning compositions and the method of using the same are disclosed, where the compositions include one or more alkanolamines, one or more ether alcohol solvents or aromatic containing alcohol, one or more corrosion inhibitors, and optionally one or more secondary solvents.