marangoni drying

Marangoni drying uses IPA vapor gradients at the water surface to achieve spot-free drying without watermarks. **Principle**: IPA vapor condenses at water-wafer interface, creating surface tension gradient. Lower surface tension IPA pulls water away from wafer surface. **Mechanism**: Marangoni effect - fluid flows from low to high surface tension. IPA at surface pulls water with it as wafer exits water. **Process**: Slowly lift wafer from DI water bath while IPA vapor is present above the water. Water sheet is pulled down off wafer. **Advantages**: No watermarks or residue spots. Superior to spin drying for particle-critical processes. **Applications**: Critical cleans where any residue causes defects. Post-oxide etch, pre-gate, advanced node processing. **Equipment**: Specialized dryers with IPA delivery, temperature control, lift mechanism, and ultra-clean environment. **IPA purity**: High-purity IPA required. Contamination in IPA transfers to wafer. **Slow process**: Slower than spin drying due to controlled withdrawal rate. **Environmental**: IPA vapor must be captured and treated.