I’m sure the RCA process for cleaning silicon wafers was invented when Werner Kern got drunk in the lab one day and decided to have some fun…
How else would any sane man come up with the idea of taking a half litre each of several of the most corrosive things you can image then heat them up until just below boiling, then chuck in something that makes it fizz and froth and pump out ammonia fumes?
That’s just step one.
Step two is more of the same but using something even more corrosive and toxic – hydrofluoric acid. This stuff eats through glass at about the same rate warm water eats through ice. Oh, and it boils as it does it and pumps out toxic gas.
Step three is tame in comparison, it just sits there looking like water. Still nasty and corrosive as you find out when you get some on your gloves / skin.
You go through all this to get a nice shiny, contaminant free silicon wafer, atomically flat – an almost perfect mirror. Then you drop it on the floor watching as all your good work comes undone.
Rinse and repeat.