HARE SQ process recipe

A high-aspect-ratio SU-8-class epoxy negative photoresist covering 2-100 µm film thickness in a single coat, for polymeric MEMS, microfluidics and micromachining, with vertical sidewalls suitable for permanent structures.

https://nanyte.com/photoresists/hare-sq · last updated 2026-07-26

At a glance

Download PDF

Manufacturer: KemLab Inc.
Grades: SQ 2 · SQ 5 · SQ 10 · SQ 25 · SQ 501
Tone: negative
Chemistry: Epoxy (SU-8 type)
Thickness: 2–100 µm
Developer: KemLab SQ Developer (SU-8 PGMEA)
Applications: MEMS structural · Microfluidics · High aspect ratio

Cross-checked — two independent extractions agree on the spin curve and the single-value figures.

Coat
2–100 µm
Expose
Develop
Solvent

Substrate
Resist
Exposed

The exposed resist stays after development; the unexposed film dissolves. Schematic cross-sections for HARE SQ — feature width, film aspect ratio and sidewall angle are illustrative, not to scale.

—01 / Coating

Spin coating

SQ 2
SQ 5
SQ 10
SQ 25
SQ 50

Data points

HARE SQ — film thickness (µm) by spin speed (rpm)
Series	rpm	µm
SQ 2	1000	3.8
	2000	2.1
	3000	1.6
	4000	1.4
SQ 5	1000	11
	2000	5.7
	3000	4.3
	4000	3.5
SQ 10	1000	23
	2000	12
	3000	9.0
	4000	7.0
SQ 25	1000	48
	2000	23
	3000	17
	4000	13
SQ 50	1000	98
	2000	48
	3000	33
	4000	24

Values are the manufacturer’s starting points, not a guarantee — characterize on your own tool. Series digitized from a published figure are approximate (±10 %).

SQ 2: read from the left-hand spin-curve chart (unlabeled figure, square-marker solid line = SQ 2), p.2 of SQ Series TDS; legend explicitly lists 'SQ 2' and 'SQ 5' as the two curves on this chart. The 2000 rpm read (~2.1 µm) is consistent with the Processing Guidelines table's stated reference point 'SQ 2, 2 µm @ 2000 rpm.'

SQ 5: read from the left-hand spin-curve chart (triangle-marker dashed line = SQ 5), p.2 of SQ Series TDS; legend explicitly lists 'SQ 5'. The 2000 rpm read (~5.7 µm) is consistent with the table's reference point 'SQ 5, 5 µm @ 2000 rpm.'

SQ 10: read from the right-hand spin-curve chart (diamond-marker solid line = SQ 10), p.2 of SQ Series TDS; legend explicitly lists 'SQ 10', 'SQ 25', 'SQ 50'. The 2000 rpm read (~12 µm) is reasonably consistent with the table's reference point 'SQ 10, 10 µm @ 2000 rpm' (figure-read tolerance).

SQ 25: read from the right-hand spin-curve chart (circle-marker dashed line = SQ 25), p.2 of SQ Series TDS; legend explicitly lists 'SQ 25'. The 2000 rpm read (~23 µm) matches the table's reference point 'SQ 25, 25 µm @ 2000 rpm' closely.

SQ 50: read from the right-hand spin-curve chart (triangle-marker dashed line = SQ 50), p.2 of SQ Series TDS; legend explicitly lists 'SQ 50'. The 2000 rpm read (~48 µm) matches the table's reference point 'SQ 50, 50 µm @ 2000 rpm' closely.

5 series redrawn from the manufacturer's published data — hover to read between points, click to pin.

Coat program uses a 5-10 second spread cycle; spin time at final speed is 30 seconds (TDS p.2, Coat).
Both spin-curve charts plot 1000-4000 rpm only (tick marks extend to 5000 but no data point is plotted there), so no 5000/6000 rpm value is reported for any grade.
Edge-bead removal (EBR) is explicitly called out as necessary: 'It is necessary to remove this thick edge bead to reduce hotplate contamination... By removing the edge bead, the photomask can be positioned closer to the wafer, improving aspect ratio and resolution' (p.3) — KemLab names its own 'KL EdgeClean EBR' solvent for this step.
The Processing Guidelines table's last row is labeled 'SQ 50 | 100 µm' — this repeats the 'SQ 50' product name from the row above it (which is 50 µm), rather than a distinct 'SQ 100' designation; quoted verbatim as printed, since the right-hand spin-curve chart shows only three curves (SQ 10, SQ 25, SQ 50) with no separate 100 µm curve, consistent with this being a second process recipe for the same SQ 50 material coated thicker at lower spin speed, not a sixth SKU.

Adhesion: HMDS not required — Not addressed.

—02 / Bake

Soft bake

Soft bake: Not published — characterize on-tool
Notes: Softbake is a two-step contact-hotplate bake (65°C step then 95°C step) 'to minimize film stress and adhesion issues' (p.3), with both step times scaling by thickness — fundamentally a two-step process, so no single temp/time pair describes it.

SOURCE: Processing Guidelines table, p.2, and Softbake section, p.3 of SQ Series TDS

—03 / Exposure

Exposure dose

Near-UV broadband on silicon takes 200 mJ/cm² at 2 µm and a flat 180 mJ/cm² everywhere from 5 µm to 100 µm — the manufacturer calls these nominal and says they move with tool, film and process. Run a dose array on your own tool to land the working dose.

Not published for this resist: Dose at 365 nm, Dose at 405 nm — characterize on-tool.

—04 / Development

Development

Developer: KemLab SQ Developer (SU-8 PGMEA)
Method: immersion
Rinse: Isopropyl alcohol (IPA) rinse and dry (TDS p.3, Develop).
Developer family: Solvent

SOURCE: Processing Guidelines table (column header 'Develop Immersion'), p.2, and Develop section, p.3 of SQ Series TDS

—05 / Post-processing

Hard bake, etch & strip

Storage: Avoid light; store in an upright airtight container at 4-21°C or room temperature. If refrigerated, bring up to room temperature before opening.

SOURCE: Hardbake section, p.3 of SQ Series TDS

—06 / Applications

Where it's used

MEMS structural Microfluidics High aspect ratio

Practical notes from the datasheet

This datasheet's own title and running header are 'SQ Series' throughout — it never uses the name 'HARE SQ' anywhere in the body text. The KemLab product webpage this PDF was found on (kemlab.com/haresq) is titled 'HARE SQ Negative Epoxy,' and a second webpage (kemlab.com/sq-su8-epoxy-photoresist) titled simply 'SQ' links to this identical PDF. 'HARE' most plausibly stands for 'High Aspect Ratio Epoxy,' matching the TDS's own subtitle 'High Aspect Ratio SU-8 Epoxy Photoresist' — treated here as the same product under two marketing names, not as two distinct products, since no second, differently-numbered datasheet was found. The chemistry is explicitly stated as 'SU-8 polymer epoxy' (FEATURES box, p.1) — an SU-8-class thick-film epoxy negative resist, not merely SU-8-like. Both softbake and PEB are recommended as deliberate two-step (65°C then 95°C) bakes specifically to manage film stress and cracking in thick films, and the process explicitly requires edge-bead removal to protect hotplates and improve achievable aspect ratio. Notably, unlike every other KemLab TDS read for this library, this document publishes no resist-removal/stripper section at all — consistent with the general difficulty of stripping thick, heavily-crosslinked SU-8-class epoxy negatives (especially once hardbaked above 150°C for permanent use), so no stripper value is asserted here; process/tooling should plan around that difficulty rather than assume a solvent strip will work as with the manufacturer's other product lines. This is a permanent structural resist, not a lift-off resist — KemLab markets its separate APOL-LO 3200 series for lift-off profiles.

—07 / Sources

Sources & disclaimer

Cited above

SQ Series TDS Rev 3-2025, 'PROCESSING GUIDELINES' table (p.2), Product column: SQ 2, SQ 5, SQ 10, SQ 25, SQ 50. SQ 50 appears on two rows (50 µm and 100 µm process points); there is no SQ 100 product.

Research using this resist

Sooriyaarachchi et al.. ZnO Nanowire-Anchored Microfluidic Device With Herringbone Structure Fabricated by Maskless Photolithography. Biomedical Engineering and Computational Biology (2020). doi:10.1177/1179597220941431
A herringbone-structured microfluidic device anchored with ZnO nanowires, for extracting microRNA from urine extracellular vesicles. The resist was spin-coated and then patterned by maskless direct-write lithography on a Microwriter ML3, with the matching HARE developer.
Hernandez et al.. Fully Automated Microsystem for Unmediated Electrochemical Characterization, Visualization and Monitoring of Bacteria on Solid Media; E. coli K-12: A Case Study. Biosensors (2019). doi:10.3390/bios9040131
The resist forms the confinement microstructures of an automated microsystem for electrochemical monitoring of bacteria on solid media: a polymeric layer carrying a 3 mm culture chamber connected to a microchannel, constraining E. coli growth toward embedded gold microelectrodes.

Manufacturer datasheet values are starting points; optimal parameters depend on your substrate, equipment and environment. Product names and trademarks belong to their respective owners. NANYTE is not affiliated with the manufacturers listed. Last updated 2026-07-26.

Cite this recipe

NANYTE. "HARE SQ process recipe." NANYTE Photoresist Library. https://nanyte.com/photoresists/hare-sq. Accessed 2026-07-26.

Ready to run this process on your own tool?Talk to an engineer →

Expose it at 365 and 405 nm

NANYTE BEAM is a desktop maskless lithography system with software-selectable dual-wavelength exposure and 16-bit grayscale — no photomask, no mask cost, same-day iteration.

What is NANYTE BEAM?

Improve this recipe

Run this resist in your lab? Send us what actually works, or flag a value that's wrong. No account, no email needed — a handle and affiliation are optional and become your credit line. Every contribution is checked against published sources before it appears.