Produces Caro's Acid / Peroxymonosulfuric acid, can get same/better result typically by using that

“A typical mixture is 3:1 concentrated sulfuric acid to 30% hydrogen peroxide solution; other protocols may use a 4:1 or even 7:1 mixture” [Wikipedia]

Compatibility

Since its typical use is to remove organics, don't expect many organic things to survive. Sources always say to avoid plasitcs, unclear how fluorinated plastics do

“Piranha is compatible with teflon and borosilicate glass” [AMC]

Metals?

AZ etch rates from etch bible:

  • “Evaporated Al in piranha etches at >5200 nm/min”
  • “evaporated Cu at 88nm/min”
  • “spin-on polyimide >17,000 nm/min”
  • “Oxygen plasma eats polyimide at 370nm/min and is “slow or zero” for Cu/Al”

“The Piranha (also known as sulfuric-peroxide) parts 96% H SO :1 part 30% H O . used here is a mix of . The hydrogen peroxide is added just before use. It is used as a cleaning solution that strips organics and some metals. In these tests, it was indeed found to etch photoresist, the resist pen, and polyimide very rapidly, but only slowly attacked the Parylene C. It also etched aluminum, nickel, and silver rapidly. Chromium was etched slowly, which allows it to be used for the cleaning of photomasks.” [Etch rates part II]

References

 
piranha_solution.txt · Last modified: 2013/11/17 02:08 by mcmaster
 
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