chamber clean

Chamber cleaning removes process byproduct buildup from chamber walls, fixtures, and components to maintain process stability and prevent particle contamination. Cleaning methods: (1) In-situ plasma clean—most common, uses fluorine-containing gases (NF3, SF6, CF4 + O2) to etch deposits between wafers or lots; (2) Remote plasma clean—plasma generated outside chamber for lower ion bombardment damage; (3) Wet clean—chamber opened, components removed and cleaned with solvents/acids; (4) Bead blast—mechanical removal of heavy buildup (kit parts). Clean frequency: every wafer (thin films), every lot, every N wafers (based on SPC data). Clean endpoint detection: optical emission spectroscopy (monitor fluorine peak decay), fixed time (conservative). Chamber condition monitoring: particle adders, process drift, reflectometer monitoring of wall conditions. Post-clean: chamber seasoning with dummy wafers to restore stable wall conditions. CVD chambers: heavy deposition requiring frequent cleans. Etch chambers: polymer buildup from photoresist and etch byproducts. Trade-offs: frequent cleans improve stability but reduce throughput, consume parts faster. Clean recipe optimization: minimize clean time while achieving complete removal. Critical for consistent process results and low defectivity.