KemLab 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 2026-07-10

At a glance

Manufacturer: KemLab Inc.
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.

Coat2–100 µm

—01 / Coating

Spin coating

KemLab HARE SQ is spin-coated to 2–100 µm. The curve below is redrawn from the manufacturer's published data — read your target thickness off the vertical axis and take the matching spin speed as a starting point.

SQ 2
SQ 5
SQ 10
SQ 25
SQ 50

Data points

KemLab 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; verify on your own tool. Characterize on-tool. Series digitized from a published figure were independently cross-checked by a second blind read; treat those values as 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 values 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. Substrate Preparation (p.2) states only that 'SQ Series adheres to variety of substrates; including silicon, gold, aluminum, glass, and chromium. For maximum adhesion, substrates should be clean and dry prior to applying SQ epoxy photoresist' — no HMDS or other primer is mentioned, unlike KemLab's other (non-epoxy) resist datasheets which explicitly recommend HMDS. hmds is left null rather than false, since the document is silent rather than stating a primer is unnecessary.

—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. Left null because the process is fundamentally two-step, not a single temp/time pair. Per-grade values from the Processing Guidelines table (p.2): SQ2 (2 µm) 65°C/1min + 95°C/1min; SQ5 (5 µm) 65°C/1min + 95°C/3min; SQ10 (10 µm) 65°C/2min + 95°C/5min; SQ25 (25 µm) 65°C/3min + 95°C/7min; SQ50 (50 µm) 65°C/5min + 95°C/15min; SQ50 (100 µm process point) 65°C/10min + 95°C/30min.

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

—03 / Exposure

Exposure dose

The manufacturer does not publish a clearing dose for KemLab HARE SQ. Determine it with a dose array on your own tool.

As published: Broadband on Si with a 360 nm cutoff filter (Processing Guidelines table column header, p.2). The narrative Exposure & Optical Parameters section (p.3) states SQ is 'designed for near UV (350-400nm) exposure wavelengths' and that 'Exposure dose will vary depending on the exposure tool set, film thickness, and process conditions' — explicitly warning against treating the table doses as universal. Sensitivity is separately listed as 'NUV, Broadband, i-line' in the FEATURES box, but no dose is attributed specifically to i-line/365 nm.

—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. Keep away from oxidizers, acids, bases and ignition sources (TDS p.4, Storage).

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

—06 / Applications

Where it's used

MEMS structuralMicrofluidicsHigh aspect ratio

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 (see spinNotes). 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 (liftoffSuitable is set false; KemLab markets its separate APOL-LO 3200 series for lift-off profiles).

—07 / Sources

Sources & disclaimer

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 2026-07-10.

Cite this recipe

NANYTE. "KemLab HARE SQ process recipe." NANYTE Photoresist Library. https://nanyte.com/photoresists/hare-sq. Accessed 2026-07-10.

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