RCA DHF Clean
The Dilute Hydrofluoric Acid (DHF) dip removes the native silicon
dioxide layer along with any trapped inorganic contaminants, indluding
most metals. This step can reintroduce organic contamination
because the hydrophobic surface is prone to hydrocarbon adsorption.
For this reason, an additional SC-1 step is sometimes added after
the HF dip to regrow a protective oxide layer.
NOTE: Teflon carriers are slightly porous can slowly outgas HF.