sc1 (standard clean 1)

SC1 (Standard Clean 1) is an ammonia-peroxide cleaning solution that removes organic contamination and particles from silicon wafer surfaces. **Recipe**: Typically 1:1:5 to 1:2:7 ratio of NH4OH : H2O2 : H2O. Also called APM (Ammonia Peroxide Mixture) or RCA-1 clean. **Developed by**: RCA in the 1960s as part of the RCA cleaning sequence. Still foundational to semiconductor cleaning. **Mechanism**: H2O2 oxidizes organics. NH4OH provides slight silicon etch with undercutting that lifts particles. Combined with megasonic for particle removal. **Temperature**: Typically 60-80 degrees C. Higher temperature increases cleaning rate but also etch rate. **What it removes**: Organic contamination, particles, some light metals. Does not remove heavy metal contamination effectively. **Followed by**: Often SC2 (HCl + H2O2) which removes metal contamination. The two form the classic RCA clean sequence. **Etch consideration**: Etches oxide slightly. Amount depends on concentration, time, temperature. **Modern variations**: Dilute SC1, single wafer spray versions, ozone-based alternatives. **Criticality**: Pre-gate clean must be perfect. SC1 is often part of critical cleans.