Direct-Write Lithography Recipes

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
AZ4620
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.

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.

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