Gold Lift Off

This process is successful and highly repeatable. It has been used on 30+ wafers.

• Turn on EV620 lamp
• Visually inspect wafer for defects
• Degrease/Dry 
• Dehydration bake - 2min 110°C
• Spin (Recipe #3, 4500uL SPR220)
• Expose (210 dose, hard contact) (soft contact okay with features are larger)
  • Inspect mask and clean or blow off with nitrogen to remove debris
  • Inspect sample and blow off with nitrogen to remove debris after loading onto substrate holder
  • Align the alignment marks so that pattern aligns with crystal plane
• Develop 917MIF 45sec→ Inspect
• Sputter
  
  • 30sec presputter Ti with shutter closed. Then 2.5min Ti, 300W, 5e-3 Torr
  • Shutter open, no pre-sputter. 5min Au, 300W, 5e-3 Torr
• Lift-off in ultrasonic cleaner
  • Ultrasonic settings: power 1, temp <RT, timer 10min.
  • Load sample into 1165 remover in glassware. Put in ultrasonic cleaner. Begin 10min liftoff
  • Load sample into acetone in glassware. Put in ultrasonic cleaner. Begin 5min liftoff
  • Load sample into IPA in glassware. Put in ultrasonic cleaner. Begin 5min liftoff
    
  • Note: these multiple lift-off steps are required to remove tiny flakes of material that settles on the sample.
  • Note: do not let the sample sit with the ultrasonic power off. Otherwise the metal flakes will settle onto gold.
  • Note: when transferring sample from 1165 to Acetone, and from Acetone to IPA, and from IPA to degrease, always quickly agitate the sample to remove and floating flakes off the surface of the sample.
  • Note: Degrease glassware in between steps.
  • Note: Use 2 glassware so that you can quickly transfer sample from 1165 to acetone, and from acetone to IPA.
• Degrease/dry → inspect
  
  

The material presented in this work was carried out by Joseph Maduzia, Senior Research Engineer, within the Department of Mechanical Science and Engineering at the University of Illinois. It was provided in the spirit of cooperation to educate future generations of engineers and scientists.