Reduction of Waste in Semiconductor Manufacturing Plant (Sulfuric Acid Recycling Technology)

Technologies to collect and reuse sulfuric acid waste is attracting attention to reduce industrial waste in semiconductor manufacturing plants. Reusing sulfuric acid has a high economic value. By using sulfuric acid recycling equipment based on an atmospheric distillation method, we evaluated the recovery percentage of sulfuric acid, the concentration and quality of recycled sulfuric acid, and the influence of recycled sulfuric acid on semiconductor devices. The recovery percentage of sulfuric acid waste was 95% or more, and the quality of the recycled sulfuric acid was equivalent to or better than the sulfuric acid used for the electronic industry. Even when recycled sulfuric acid was used for resist stripping and wafer cleaning processes, the resist stripping capability and the dielectric breakdown voltage characteristics of gate oxide film were equivalent to or better than sulfuric acid used for the electronic industry. This indicated that the use of recycled sulfuric acid had no negative influence on semiconductor devices. By installing sulfuric acid recycling equipment based on an atmospheric distillation method, a semiconductor manufacturing plant can perform all collection, refinement and supply processes, and can contribute to decreasing industrial waste.