SU8

[updated Xiaoyu 08/11/2023]

1. substrate cleaning-AMI clean

   • acetone rinse

   • methanol rinse

   • IPA rinse

2. Omnicoat spin-coating

   • 500 rpm, 5s, 100 rpm/s

   • 3000 rpm, 40s, 300 rpm/s

3. Bake at 200 deg. for 1 min

4. Repeat this process at least two (~26nm expected for 2 layers)

   • 3 times recommended -> Microchem suggest 3 layers of Omnicoat coating

5. SU8-3005 spin-coating

   • Dispense it to cover 70% of the wafer surface

   • 500rpm, 5s, 100rpm/s

   • 4000rpm, 40s, 300rpm/s ->5.5um
     3000rpm, 40s, 300rpm/s ->6.7um

6. soft bake

   • Bake at 95 deg. for 3 mins.

7. Exposure with the MA6 Aligner

   • CI1 setting for 30s exposure in Hard contact mode (typically for large patterns like back-side opening masks)

   • Note : 10 s exposure / 1 min development for ANP rev.1 & 2 bondpad etch (8.5 s exposure also works good)

   • Note :  8.5 s exposure / 1 min development for ANP rev.2 slit etch mask

   • Note : For the small 5 um vent hole patterns, I ended up reducing 6.5 s exposure time with 3 layers of Omnicoat

   • Note : If you perform vacuum contact with SU8, it will stick to your wafer and hard to retrieve wafers…

8. Exposure with the Aligner

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9. Post Exposure Bake (PEB)

   • Bake at 95 deg. for 2 mins

10. Development

    • Prepare two dishes for SU8 developer and IPA
      The SU8 developer is labeled: 1-Methoxy-2-Propanol Acetate

    • Agitate sample in the SU8 developer dish (1min)

    • Put sample in the IPA dish, agitate and spray IPA and dry using N2 gun
      Note: Do not rinse with DI water after IPA spraying

11. Omnicoat development

    • O2 Plasma etch in Oxford RIE 80 for 2 mins

    • Recipe: YS Omnicoat removal
      Note: Etch recipe – Foward power : 100W / O2 : 35sccm / 190mT / 30s by Omnicoat manual
      Note: Total 2 min etch = 3 x each layer for 30s etch + 30s overetch