Quartz Tanks

No. Hydrofluoric acid dissolves silicon dioxide, and flamed fused quartz is silicon dioxide, so HF attacks the tank itself at any concentration, including dilute HF and buffered oxide etch. HF, BOE, and HF-based oxide strips require a fluoropolymer bath instead. Modutek supplies Teflon tanks for these steps. On a wet bench, running both, the HF station uses Teflon, and the remaining stations use quartz.

The cutout has to clear the tank flange and the deck area it sits on, not just the vessel itself, which is why the deck cutout and deck area figures in the matrices are both larger than the vessel ID. Below deck, you also need clearance for the drain, so allow approximately 4 additional inches in overall depth beyond the figure in the table. Facility planners should size the bench opening from the deck cutout column, not the vessel dimensions.

Thermal shock is rarely the cause. Flamed fused quartz has extremely low thermal expansion, which is exactly why it survives repeated heat-up and cool-down cycles that would crack other glass. The two real failure modes are mechanical and chemical. Mechanically, a chip or a deep scratch from cassette handling becomes a crack initiation site that propagates under thermal cycling, so damaged tanks should be replaced rather than run. Chemically, quartz is slowly attacked by strong alkali above roughly pH 9 at elevated temperatures, so hot caustic baths should be run in Teflon.

No. Quartz tanks are fabricated from semiconductor-grade silicon dioxide, with no metallic constituents to leach, which is why they are used for cleaning steps whose entire purpose is to remove metal ions from the wafer surface. On QFa Series recirculating tanks, the all-quartz flare connections extend that same inertness throughout the fluid path, so the chemistry never contacts a dissimilar material between the inlet and the drain.