ASML DUV: Edge Bead Removal via Photolithography

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The metal edge-bead removal masks are in the Suss MA-6 Contact Aligner drawers, and I recommend the "4mm recessed".

It loses a bit more device area, but significantly lowers the risk of breaking a wafer in clamped systems such as the DSEiii.

(This process can easily be transferred to I-Line photoresists, using the Suss MA-6 for flood exposure instead of DUV Flood expose.)

Photo-EBR Process

  • Spun/cure a DUV photoresist using your standard photolith. params (for example UV6).
  • Place the wafer on the DUV Flood Exposer with the metal mask in place.  
  • Turn on rotation on slow (so mask doesn't move), lamp warmup is not required.
  • Expose for 13 sec, with slow rotation.
  • Optionally: PEB 135°C, 60sec, Develop, dry (in SRD), then proceed.  This did not affect my primary lithography when I did this step separately.  I've also done photo-EBR where I combined this EBR exposure with the primary Imaging litho. and only did a single develop.
  • Load wafer into ASML & Expose your process
  • PEB 135°C, 90sec
  • 300MiF develop as per your normal process.
    • (If you did not develop the EBR yet, it should go away in this step.)
Demis D. John, 2018-10-22