Method of removing metallic, inorganic and organic contaminants from chip passivation layer surfaces

Abstract

A method of removing and/or reducing undesirable contaminants removes residues including graphitic layers, fluorinate layers, calcium sulfate (CaSO) particles, tin oxides and organotin, from a chip passivation layer surface. The method uses a plasma process with an argon and oxygen mixture with optimized plasma parameters to remove both the graphitic and fluorinated layers and to reduce the level of the inorganic/tin oxides/organotin residue from an integrated circuit wafer while keeping the re-deposition of metallic compounds is negligible. This invention discloses the plasma processes that organics are not re-deposited from polymers to solder ball surfaces and tin oxide thickness does not increase on solder balls. The ratio of argon/oxygen is from about 50% to about 99% Ar and about 1% to about 50% Oby volume. Incoming wafers, after treatment, are then diced to form individual chips that are employed to produce flip chip plastic ball grid array packages.