Etch & Clean Equipment
Wet Clean Systems
Chemical cleaning sequences, megasonic cleaning, and single-wafer tools
Wet Clean Chemistry
Wet Clean Chemistry
Wet cleaning removes particles, metals, and organic contaminants between process steps. A wafer is cleaned 100+ times during fabrication. Standard cleaning sequences:
- SC-1 (APM): NH₄OH:H₂O₂:H₂O — removes particles and organic contamination by etching a thin oxide layer and lifting particles off. The workhorse clean.
- SC-2 (HPM): HCl:H₂O₂:H₂O — removes metallic contamination (Fe, Al, Mg) by dissolving metals as soluble chloride complexes.
- HF dip: Dilute HF (0.5–1%) — removes native oxide and some embedded metals. Also used for oxide etch.
- SPM (Piranha): H₂SO₄:H₂O₂ — aggressive organic removal for heavy contamination (e.g., post-implant resist stripping).
Key Concept: From Batch to Single-Wafer
The industry is shifting from batch wet benches (25 wafers immersed together) to single-wafer spin clean tools. Single-wafer tools offer better uniformity, lower chemical consumption, reduced cross-contamination risk, and compatibility with advanced process control.
Knowledge Check
Knowledge Check
1 / 1What does the SC-1 (APM) clean remove?