Patent ID: 8658583

Claim:
In a method for manufacturing a photoresist stripper solution for a metal-containing substrate comprising the steps of: a) introducing into a blending zone one or more organic sulfonic acids having the general formula: i) wherein n≧1, and R is independently an alkyl group, substituted alkyl group, aryl group, substituted aryl group, or an aryl/alkyl group; b) uniformly blending with the one or more organic sulfonic acids at ambient temperature at least one or more halogen-free hydrocarbon solvents containing at least eight carbon atoms, wherein the one or more halogen-free hydrocarbon solvents is miscible with the one or more organic sulfonic acids; the improvement comprising heating the blend for a minimum period of time whereby residual amounts of sulfuric acid and sulfur trioxide present in the one or more organic sulfonic acids react with the one or more hydrocarbon solvents to form corresponding organic sulfonic acids, and the resulting amounts of sulfuric acid and sulfur trioxide present in the blend after heating do not cause damage to semiconductor metal substrates.