Waste Treatment

Waste treatment processes and neutralizes chemical waste from semiconductor manufacturing before disposal, ensuring regulatory compliance and environmental protection. Waste streams: (1) Acid waste—HF, HCl, H₂SO₄, HNO₃ from wet etch and clean; (2) Alkali waste—NH₄OH, TMAH (developer) from photolithography; (3) Solvent waste—IPA, acetone, PGMEA from resist processing; (4) CMP waste—slurry containing abrasive particles and metal ions; (5) Fluoride waste—HF-containing waste requiring special treatment; (6) Heavy metal waste—Cu, W, Co from CMP and etch. Treatment technologies: (1) Neutralization—acid-base pH adjustment to 6-9 range; (2) Precipitation—convert dissolved metals to insoluble solids (hydroxide, sulfide precipitation); (3) Coagulation/flocculation—aggregate fine particles for sedimentation; (4) Ion exchange—remove dissolved metals and ions; (5) Membrane filtration—UF/RO for water recovery; (6) Oxidation—destroy organics using ozone, UV, or chemical oxidants. Fluoride treatment: calcium fluoride precipitation (Ca(OH)₂ + HF → CaF₂), critical due to strict discharge limits. CMP waste: dedicated treatment—particle removal, metal precipitation, water recovery. Water recycling: treat and reuse water to reduce UPW consumption (40-60% reclaim rates achievable). Sludge handling: dewatering, testing, disposal as hazardous or non-hazardous based on TCLP results. Regulations: Clean Water Act, POTW discharge limits, hazardous waste (RCRA). Essential infrastructure protecting the environment while managing the complex chemical waste from fab operations.