We have developed an environmentally safe solvent for removing ashing residue of photo resist used in the production process of devices with copper wires and low-dielectric interlayers (Low-k). The inhibition of corrosion of the copper wires is very important for these devices, and then benzotriazole (BTA) has been mainly used as a corrosion inhibitor in current removers used in the process. However, BTA has a large environmental impact because it creates mutagenicity and biodegrades poorly. We have investigated typical natural heterocyclic nitrogen compounds to replace BTA. As a result, adenine, one of the safe compounds in living organisms, was found to effectively inhibit copper corrosion by forming a thin film on copper surface. Moreover, to control deterioration in Low-k films with low chemical resistance, we replaced a part of amino alcohol in the solvent with tetrahydrofurfuryl alcohol (THFA), which easily dissolves in water and controls the deterioration of Low-k films. The resulting remover, composed of adenine, 2-methyl-aminoethanol, THFA, lactic acid, and water, not only effectively removes the ashing residue from copper/Low-k devices, but also greatly reduces the environmental impact because it is composed of safe and biodegradable compounds.
