Direct-Write Lithography Recipes

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Maskless Aligner (Heidelberg MLA150)

Photolithography Recipes for the Heidelberg MLA150. All recipes were characterized on blank Silicon wafers. For different substrate coatings/materials, you will likely need to run a focus-exposure matrix ("series" exposure mode), using our params as a starting point.

These recipes use the same spin and bake params as our contact aligner and stepper recipes, using built-in hotplates on the photoresist spinner benches.

Any I-Line PR is usable, although we only characterized a select few below. Run your own Focus-Exposure Matrix to characterize a new PR.

Positive Resist (MLA150)

We found that positive PR's worked well with the 405nm laser - the 375nm laser would likely also work. Sub-micron features are possible. Overexposure is recommended to avoid stitching and horiz/vert discrepancies, compensate using CD Bias as described here.

Note: calibrations done with the "HIMT design" will show higher dose, due to using only dark-field line/space patterns.

Resist Spin Cond. Bake Thickness Laser (nm) Exposure Dose (mJ/cm2) DeFocus PEB Developer Developer Time Comments
AZ4110 4 krpm, 30s 95°C, 60s ~ 1.1 µm 405 240 5 none AZ400K:DI 1:4 50s Used HIMT design (good for isolated lines 0.8-1um)
AZ4330 4 krpm, 30s 95°C, 60s ~ 3.3 µm 405 320 6 none AZ400K:DI 1:4 90s Used HIMT design
SPR 220-3.0 2.5 krpm, 30s 115°C, 90s ~ 2.7 µm 405 325 - 4 115°C, 90s AZ300MIF 60s Used HIMT design. 0.6-0.9µm line/space.
SPR 955-CM0.9 3 krpm, 30s 95°C, 90s ~ 0.9 µm 405 250 - 7 110°C, 90s AZ300MIF 60s Used HIMT design
THMR-3600HP 1.5 krpm, 45s;

250 rpm/s

100°C, 60s 0.430µm 405 180–220 -4 100°C, 60s AZ300MiF 20s ~0.4nm line/space:

lower dose for clear-field, higher dose for dark-field.

*PEB: Post-exposure bake

Negative Resist (MLA150)

We found that all the negative PR's we tested required the 375nm in order to be fully exposed with reasonable dose/time.

Resist Spin Cond. Bake Thickness Laser (nm) Exposure Dose (mJ/cm2) DeFocus PEB Flood Developer Developer Time Comments
AZ5214 6 krpm, 30s 95°C, 60s ~ 1.0 µm 375 35 - 5 110°C, 60s 60" AZ300MIF 60s Used UCSB design. Good for up to ~1.3um open line space.
AZnLOF2020 4 krpm, 30s 110°C, 60s ~ 2.1µm 375 340 - 3 110°C, 60s none AZ300MIF 90s Used UCSB design. Good for 2um open line space.
SU-8 2075 ~70µm 375 Extremely viscous. Pour into a wide-mouthed bottle, dispense directly from bottle. Replace napkin at end.
*PEB: post-exposure bake. For AZ 5214-IR, this performs Image Reversal, and requires flood exposure with the MA6 or MJB aligner afterwards, before develop.

Greyscale Lithography (MLA150)

AZ4620 is the manufacturer-recommended PR for greyscale litho.

Resist Spin Cond. Bake Thickness Exposure Dose (mJ/cm2) Focus Offset PEB Flood Developer Developer Time Comments
AZ4620 ? krpm/30” 95°C, 60” 60" AZ300MIF 60s
  • TBD