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Non-Standard Nitride Strip, contaminated

This process module covers the stripping of nitride at wbflexcorr-3and-4 or wbflexcorr-1and-2.

NITRIDE STRIP - WET, contaminated

Important Notes:

  1. Use your own designated quartz beaker to prevent contaminating your wafers. If your wafers are already gold contaminated you may use the beakers or holders at wbflexcorr-3and-4 or wbflexcorr-1and-2 (most of them are gold contaminated). Once you use a contaminated beaker -- your wafers must be considered contaminated and are restricted as to what equipment they may use.

Process:

 

  1. Pour fresh Phosphoric Acid in your own designated quartz beaker and cover with your own designated lid to prevent evaporation.
  2. Heat solution to 155C.
  3. NOTE: Wafers should not have resist on them when going into nitride strip bath.
  4. Use your own designated Teflon cassette for this etch to prevent contamination.
  5. Dip wafers in your own designated beaker of DI water for 15 second.
  6. Immerse in 6:1 Buffered HF (in your own designated plastic or Teflon beaker) for 30 seconds. This is to remove any oxide layer that is on the top of the nitride.
  7. Overflow rinse (in your own designated beaker) for 5 minutes.
  8. Blow Dry.
  9. Inspect.
  10. Immerse the wafers in DI water for 15 seconds (in your own designated beaker).
  11. Immerse the wafers in the hot Phosphoric (nitride strip) solution and replace the lid to prevent evaporation which effects the etch rates. The etch rate of nitride is about 32A/min.  Oxide and silicon etch at about 0.8A/min.  Over-etching by 20-40% is not unusual in order to clear the samples of nitride.
  12. Overflow Rinse with DI water for 5 minutes.
  13. Blow Dry.
  14. Inspect to be sure all the nitride has been removed (i.e. measure oxide under the nitride -- if it is less than or equal to what you had originally, the nitride is off.

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