Contact aligner walk through

IMPORTANT NOTE: The recipe below is for illustrative purposes only. For current recipe see the main Device Making page.

Note: Data sheets for S1813 and LOR3B are available at T:\Physics\Minot Group\Group documents\Manuals\Device Making

  1. Start-up
    • Turn on power to aligner
    • Turn on microscope light
    • Turn on power to mercury lamp
    • Turn on nitrogen flow, and check pressure. Press start on the front of the lamp power supply
    • Turn on power on aligner control panel
    • Wait 30 minutes for the lamp to heat up
    • Turn on both hot plates (190C & 115 C)
  2. Substrate Preparation (optional)
    • Sonicate
    • Scribe the back side (for transparent substrates)
    • Wash substrate with acetone, isopropyl alcohol, and DI water
    • Bake for ten minutes
      • A new silicon wafer may not require the preceding steps
    • Get a chuck for the spinner
      • In the undergraduate lab the chuck is already attached
    • Get aluminum foil to cover spinner tray
    • Place the substrate onto the center of the chuck
    • It should be suctioned into place, and have right side up
    • Press pedal to start, check centering
    • Deposit LOR3B Photoresist (Metal deposition only)
      1. Quickly cover 2/3 of chip with LOR3B photoresist (clear color)
      2. Spin at 2500 rpm for 45 seconds
      3. Bake the substrate at 190C for 2 minutes
    • Deposit S1813 Photoresist
      1. Prepare the chip to be spun again
      2. Quickly cover 2/3 of chip with S1818 photoresist (red color)
      3. Spin at 4000 rpm for 45 seconds
      4. Bake the substrate at 115C for 2 minutes (HF procedure is different, see below. Idea for quartz)
  3. Exposure
    • Place the mask on the mask holder by flipping the holder upside down and placing the mask on top. The chrome side should now be facing up
    • Press the vacuum mask button, and check if the mask is secure
    • Place the mask in the aligner and screw down
    • Check for correct spacing between the sample and mask
      1. Put a clean 'dummy' substrate on the chuck
      2. Adjust front dial so that when levers are in contact mode the chip doesn't touch the mask
      3. Slowly adjust front dial until the substrate touching the mask just pushes the fine spacing adjustment lever toward the separated position
      4. When the fine spacing adjustment lever is in the contact position you should be able to see an interference pattern created between the mask & substrate. When the lever is in the separation position the pattern should disappear.
    • Remove the dummy substrate & place the sample on the tray making sure it lines up well with the mask
    • One method to do this is to align the microscope with the corner of the mask, then remove the mask, and align the corner of the sample to the same spot.
    • Place the aligner in contact
    • Align mask with substrate ( adjust separation lever )
      • For catalyst pads: a 2 um shift towards gaps gives good results
    • Set the exposure time
      • Range 3sec minimum, standard 5sec, 8 over exposed)
      • Etch 4 sec
      • metal exposure: 5sec
      • exaggerated catalyst pads: 5-8sec
    • Press expose
  4. Developing
    • Take out the container for the photo-resist waste
    • Take out the developing solution (Insert developer type here)
    • Pour the developer into an appropriately size beaker
    • Place the sample into the developer for about 10 seconds and shake gently. Lower exposure times may take longer. If you can see a red residue on the sample, it is under developed. The sample can be placed back in the developer if it appears underdeveloped
    • Take out and immediately wash with DI water, washing over the waste container
  5. HF etching
    • Spin S1813 4000rpm 45 sec
    • Bake 85 for 2min
    • expose 4 sec
    • Bake 85 for 3min
    • Develop 10sec with gentle agitation
    • Bake 115 for 5min
    • Etch for around 1 min, etch rate is 800A/min (Soon will have slower rate etch solution)
  6. Clean up
    • Pour the developer into the waste container
    • Wash the chuck with IPA/DIwater over the waste container
    • Return the chuck
    • Take out the photo resist waste bag
    • Remove the aluminum foil and place it into the bag, being careful not to hold any photo-resist outside of the fume hood.
    • Close the waste containers and put them away
    • Wash the counter top with acetone and a paper towel.
  7. Shut Down
    • Turn off the hot plate and spinner
    • Turn off the microscope light
    • If no one plans to use the aligner within the next 24 hours turn off the mercury lamp
    • Leave the nitrogen flowing for 30 minutes while it cools
    • Turn off the aligner
    • Turn off the aligner power supply.