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-- TimBotzem - 2012-05-07

Recipes (related to quantum dot processing) should be stored here.


Cleanroom and some equipment is NOT very clean so special care has to be taken sometimes.

  • don't expose samples to cleanroom atmosphere if avoidable
  • clean beakers with aceton/IPA in ultrasonic bath prior usage
  • while spinning resist: -leave samples in IPA as long as possible
    -right before dropping resist flush sample with nitrogen
  • whenever possible flush samples with aceton/IPA when removing from solvants (e.g. after developing, lift-off, etc.)
  • store in desiccator/nitrogen box

Current recipes

  • optical positive : AR-U 4040 @4000/6000rpm for 30' (prog 9) -> bake @100C for 2" -> 10' exposure -> 30' develop in pos developer (AR 300-47:DI 1:2) -> plasma asher prog 5
  • optical negative : AR-U 4040 @4000/6000rpm for 30' (prog 9) -> bake @90C for 2" (15' exposure -> post bake @ 115 for 5" -> flood exposure for 45'-> 33' develop in neg developer (AR 300-47:DI 2:3) -> plasma asher prog 5
  • ebeam positive : 1st layer 50K @6000rpm for 30' (prog 11) -> bake @180C for 5" -> 2nd layer 950K @6000rpm for 30' (prog 11) -> bake @180C for 5"
  • current recipe for QdotsProccessing

Standard cleaning (GaAs)

  • 5" ultrasonic in aceton (use plasic beaker or sample holder when using ultrasonic!!!)
  • 5" ultrasonic in IPA
  • 5" plasma asher @300W (program 2)

Plasma asher

  • turn on oxygen
  • turn main power switch on
  • press start button to start pump
  • after ~10s hit stop button
  • choose program by pressing arrow up/down
  • program 5: 5"@300W (clean samples)
  • program 2: 10'@W (remove resist leftovers after exposure)
  • vent chamber by bressing F3
  • load samples
  • close door and press start
  • remove samples when finished
  • close door and press F4 to pump down
  • switch off asher when finished
  • turn off oxygen

General lift-off

  • use plastic lift-off beaker!!!
  • put samples in warm aceton (40C, cover beaker) for approx. 5-10"
  • hold sample with tweezers in second beaker and flush it using a plastic pipette
  • put sample in first beaker (plastic!!) and 2-5' ultrasonic bath
  • flush in IPA and check under microscope
  • keep sample wet, don't let it dry
  • repeat ultrsonic bath if needed
  • flush in IPA and blowdry with nitrogen otherwise

Cleaving 5x5mm wafers

  • spin resist on wafer (see how to spin)
  • prepare: 2 q-tips, 1 microscope slide, diamond scriber, tweezer, squared paper
  • wear: facial protection, mask (Arsenid is toxic!!!)
  • under flowbox locate wafer on microscope slide with quared paper underneath
  • hold wafer with tweezer and scratch it with the scriber to receive a 5mm thick part (scratching the edge should be sufficient)
  • locate scratch over edge of the slide
  • while holding wafer with tweezer, slightly apply pressure on the freestanding part with q-tip to cleave wafer
  • continue to receive 5x5mm pieces
  • clean used equipment and dispose leftovers into GaAs waste bin with wipe

Spin resist

  • take resist from fridge and let it warm
  • only open if bottle is at roomtemperature
  • blow end of one-use-only pipette
  • use pipette tor get resist out of the bottle (don't touch bottleneck, no air bubbles,...)
  • never put resist back into bottle
  • put resist bottle back into fridge when not used any more
  • switch on spinner and pump
  • prepare heat plate
  • use wipes to cover spinner and put chuck in
  • put sample on hot plate (100) -> blow dry -> chuck
  • press arrow down button to switch on vacuum (check with tweezers)
  • drop resist on sample (first drop on wipe)
  • press I button to start spinner
  • bake sample on hot plate
  • repeat if needed for more layers
  • switch off equipment
  • clean used equipment (remove resist with acetone, use copper wire to clean vacuum line)
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Topic revision: r8 - 2013-02-21 - JanBussmann
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