Working with Piranha

Standard operating procedure

• Book the HF fumehood in CR1.

It is recommended to use a setup where you can run your process undisturbed

• Gather all necessary glassware:
  • two PTFE (Teflon) beakers
• Gather all necessary chemicals:
  • Concentrated sulfuric acid
  • Hydrogen peroxide
• Turn on MQ 30-minute timer. Flush the MQ for 30 seconds
• Make sure you have compatible tweezers: PTFE (Teflon) or steel.
• Pour some MQ in one beaker for rinsing. Dry any wet spots on the bench.
• Calculate the portions of sulfuric acid and Hydrogen peroxide that you would like to mix:

  For 3:1 sratio solurtion

  • Pour 3 parts concentrated sulfuric acid into the empty beaker.
  • Very slowly pour 1 part 30% hydrogen peroxide into the sulfuric acid.

    If H2O2 is poured too fast, fumes appear. The solution will heat up during this step.

• The solution is now ready for sample cleaning/etching.
• Dip the samples into the Piranha solution for as long as necessary.
• Rinse the samples in MQ. Avoid any organic solvents.
• Dry the samples away from the Piranha solution.
• Let Piranha cool down until at room temperature.
• Use a funnel to collect the Piranha waste in the dedicated 1L bottle located at the bottom of the left CR1 cabinet.
  • Write your name and date on the bottle
  • Do not close the cap tightly.
  • Place the bottle at the temporary storage in CR1.
• Dispose of the MQ in the sink
• Ensure that all the setup that you used (beakers, volumetrics) is back in their original location.