Photolithographic Process for AZ 3312 Positive Photoresist on Bare Silicon Wafer

  1. Clean Wafers with Piranha Etch Bath.
    1. Heat bath to 80 °C.
    2. When bath is at temperature, place wafers in sulfuric acid bath using Teflon boat and start 20 minute timer.
    3. When time is complete, take wafers out of piranha etch and place in dump washer being careful to avoid any drips of sulfuric acid. Start the timer on the dump washer.
  2. Clean and Dry Wafers in Semitool SPD015 Spin Dryer
    1. Upon completion of dump washer, place wafers in spin dryer and press start.
    2. When done, transfer wafers to different carrier boat.
  3. Apply Adhesion Promoter, HMDS, to Wafers Using Vapor Prime Oven
    1. Transfer wafers to HMDS brown Teflon boat and place in orange vapor prime oven.
    2. Make sure the gasket is properly secure and press ‘Run’ button.
    3. Upon completion of HMDS bake, about 30 minutes, let the wafers cool to room temperature.
  4. Spin Coat Wafers with AZ 3312
    1. When wafers reach room temperature, load a wafer on a prepped Headway or Brewer spin Coater.
    2. Choose the proper recipe, recipe 8 for the Headway spinner. The resist is spun at 4000 rpm to give a thickness of about 1.10 µm before baking, or 1.07 µm after baking.
    3. Dispense AZ 3312, about 6 mL per wafer, during the spin coating.
  5. Soft Bake
    1. Soft bake for 1 minute at 90 °C on a vacuum hot plate.
  6. Expose Wafer in the Contact Aligner
    1. Expose for 3.0 seconds without any filter for optimum exposure dose. Channel A of the contact aligner is set at 15 mW/cm2.
    2. Perform 1 minute 90 °C post exposure bake following exposure on contact aligner. Let cool to room temperature before development.
  7. Develop Wafer
    1. Develop wafer for 40 seconds in AZ 726 MIF Developer.
    2. Wash with deionized water to completely remove developer, and blow dry with nitrogen gun.
  8. Hard Bake
    1. Hard bake for 3 minutes at 90 °C on a vacuum hot plate.

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