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SU-8 3050 process recipe

SU-8 3050 is the highest-viscosity grade of Kayaku's five-member SU-8 3000 series, an improved, lower-stress reformulation of SU-8 2000 for thick (roughly 44-101 µm per its own digitized spin curve), high-aspect-ratio, permanent MEMS structures.

https://nanyte.com/photoresists/su-8-3050 · last updated 2026-07-22

At a glance
Download PDF
Manufacturer
Kayaku MicroChem / MicroChem Corp.
Tone
negative
Chemistry
Epoxy (SU-8 type)
Thickness
44.3–101.3 µm
Developer
SU-8 Developer (MicroChem's proprietary solvent-based developer); ethyl lactate and diacetone alcohol are also stated to work
Applications
MEMS structural · High aspect ratio · Electroplating / molding
Coat44.3–101.3 µmSoftbake95 °C · 30 min · hotplateDevelop11 min
—01 / Coating

Spin coating

SU-8 3050 is spin-coated to 44.3–101.3 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.

Spin curve for SU-8 3050: film thickness in µm against spin speed in rpm.0.00501001502001k2k3k4kSPIN SPEED (rpm)THICKNESS (µm)
Data points
SU-8 3050 — film thickness (µm) by spin speed (rpm)
Seriesrpmµm
SU-8 30501000101
200067
300050
400044

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

read from Figure 1, 'Spin speed vs. Thickness for SU-8 3000 resists (21°C US & EU)', p.1 of the Kayaku Microchem/MicroChem 'SU-8 3000 Permanent Epoxy Negative Photoresist' datasheet (BYU cleanroom mirror; no printed revision code) -- the same datasheet and figure already used for SU-8 3025 in this library. Chart plots five grades (3050/filled square, 3035/filled triangle, 3025/filled diamond, 3010/filled circle, 3005/open square), each with 4 markers at 1000/2000/3000/4000 rpm. Points were extracted programmatically from the PDF's vector content stream (PyMuPDF get_drawings()): the marker rects were matched by draw-style signature (single filled+stroked ~2.9pt square, distinct from the other four grades' triangle/diamond/circle/open-square markers) and by rank -- topmost (largest thickness) of the five stacked markers at every rpm column, consistent with SU-8 3050 being the highest-viscosity grade (12,000 cSt, Table 1) and its top-of-legend position. Axes were calibrated from the axis tick-LABEL TEXT coordinates via linear regression (not eyeballed): y-axis 0-110 µm span, x-axis 0-5000 rpm span, 1000 rpm gridlines. Method cross-checked by re-deriving the existing SU-8 3025 curve already published in this library (su-8-3025.json: 58/37/25/23 µm at 1000/2000/3000/4000 rpm) from the same drawing set using the same calibration -- this method reproduced 57.9/37.1/24.8/22.6 µm, matching the published values to within 0.4 µm (well under 2%) at every point, which validates the marker-identification and calibration approach used here for SU-8 3050. Uncertainty on the SU-8 3050 read is estimated at the same order, well under ±2%.

Redrawn from the manufacturer's published data — hover to read values between points, click to pin.

Recommended Program (family-wide, not grade-specific): dispense 1 ml resist per inch (25 mm) of substrate diameter; spin at 500 rpm for 5-10 s at 100 rpm/s acceleration (spread step); then spin at 3000 rpm for 30 s at 300 rpm/s acceleration as a generic starting point -- the actual final rpm/time for a target SU-8 3050 thickness should be read from Figure 1 ('Spin speed vs. Thickness for SU-8 3000 resists', 21°C US & EU, p.1, digitized above) or Figure 2 (23°C Japan & Asia, p.2, not digitized -- only Figure 1 is captured as the primary curve, matching the convention used elsewhere in this library for datasheets publishing two ambient-condition charts). No numeric table exists for SU-8 3050 alone -- Table 1 (p.2) only ranks the five grades by viscosity (3050: 75.5% solids, 12,000 cSt, 1.153 g/ml density). No edge-bead-removal step is described anywhere in this SU-8 3000 datasheet, and no resist rehydration hold is mentioned either.

Adhesion
HMDS not required — Adhesion promoters are stated as 'typically not required' for substrates cleaned per the recommended piranha (H2SO4+H2O2) wet etch or RIE/O2-barrel-ash prep. Exception: for applications requiring electroplating, the datasheet recommends pre-treating the substrate with MCC Primer 80/20 (HMDS).
—02 / Bake

Soft bake

Soft bake
95 °C · 30 min · hotplate
Notes
95°C is fixed across all thickness brackets; only bake TIME varies by film thickness per Table 2: 4-10 µm -> 2-3 min; 8-15 µm -> 5-10 min; 20-50 µm -> 10-15 min; 30-80 µm -> 10-30 min; 40-100 µm -> 15-45 min. This recipe's own digitized spin curve (44.3-101.3 µm across 1000-4000 rpm) falls entirely within the 40-100 µm bracket, so time_s = 1800 s is the midpoint of that bracket's 15-45 min range (unlike su-8-3025, where no confident thickness bracket could be established because that entry's curve had not yet been digitized). Convection ovens are explicitly NOT recommended -- a skin can form on the resist and trap solvent, incompletely drying the film. Vendor's own optimization check: after the prescribed bake, cool the wafer to room temperature, then return it to the hotplate; if the film wrinkles, continue baking and repeat the cool/reheat cycle until wrinkles no longer appear.

SOURCE: Table 2 'Soft Bake Times', p.2 of SU-8 3000 Permanent Epoxy Negative Photoresist datasheet, Kayaku MicroChem/MicroChem Corp.

—03 / Exposure

Exposure dose

The manufacturer does not publish a clearing dose for SU-8 3050. Determine it with a dose array on your own tool.

As published
'SU-8 3000 is most commonly exposed with conventional UV (350-400 nm) radiation, although i-line (365 nm) is recommended' (Processing Guidelines, p.1). Table 3's dose values are not explicitly labeled as i-line-only.
Post-exposure bake
95 °C · 4 min

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

—04 / Development

Development

Developer
SU-8 Developer (MicroChem's proprietary solvent-based developer); ethyl lactate and diacetone alcohol are also stated to work
Time
11 min
Rinse
Spray/wash with fresh SU-8 developer for ~10 s, then a second spray/wash with isopropyl alcohol (IPA) for ~10 s, then air/nitrogen dry with filtered pressurized gas. A white film appearing during the IPA rinse indicates under-development -- immerse or spray with more SU-8 developer and repeat the rinse. Ultrasonic or megasonic bath agitation is recommended for developing out vias/holes in high-aspect-ratio structures.
Developer family
Solvent

Not published for this resist: Dilution, Method — characterize on-tool.

SOURCE: Develop and Rinse-and-Dry sections, p.3 of SU-8 3000 Permanent Epoxy Negative Photoresist datasheet, Kayaku MicroChem/MicroChem Corp.

—05 / Post-processing

Hard bake, etch & strip

Etch resistance
Listed under Features as 'Excellent dry etch resistance' (p.1, no numeric selectivity given). The Plasma Removal section (p.4) gives an RIE recipe (200 W, 80 sccm O2, 8 sccm CF4, 100 mTorr, 10°C) specifically for STRIPPING crosslinked SU-8 -- i.e. cured SU-8 requires an aggressive dedicated RIE recipe to remove at all, consistent with strong etch resistance during normal device processing.
Stripper
MicroChem's Remover PG, 50-80°C bath, 30-90 min immersion -- swells and lifts off minimally-crosslinked SU-8 3000; achieves a clean, thorough lift-off of fully-crosslinked SU-8 3000 only if a 30-100 nm OmniCoat sacrificial layer was applied first. Will NOT remove fully-cured/hard-baked SU-8 3000 without OmniCoat underneath. To rework fully cross-linked material with no OmniCoat: oxidizing acid solutions (piranha etch), plasma ash, RIE (200 W, 80 sccm O2, 8 sccm CF4, 100 mTorr, 10°C), laser ablation, or pyrolysis.
Storage
Store upright, in tightly closed containers, in a cool, dry environment away from direct sunlight, at 40-70°F (4-21°C). Store away from light, acids, heat, and sources of ignition. Shelf life is twelve months from date of manufacture.

Not published for this resist: Hard bake, Descum — characterize on-tool.

SOURCE: Hard Bake (cure) section, p.3 of SU-8 3000 Permanent Epoxy Negative Photoresist datasheet, Kayaku MicroChem/MicroChem Corp.

—06 / Applications

Where it's used

Practical notes from the datasheet

SU-8 3050 is the highest-viscosity member (12,000 cSt, 75.5% solids, 1.153 g/ml) of Kayaku MicroChem's five-grade SU-8 3000 permanent epoxy series (3005/3010/3025/3035/3050), an 'improved formulation' of SU-8 2000 offering better adhesion and lower coating stress for thick (family-wide 4-120 µm single-coat), high-aspect-ratio (>5:1), permanent MEMS structures that are imaged, cured, and left on the device rather than lifted off. Within the 3000 series it is the thickest-coating grade at any given spin speed -- this recipe's own digitized Figure 1 read places it at 101.3 µm (1000 rpm) down to 44.3 µm (4000 rpm), stacked above 3035/3025/3010/3005 at every rpm column, consistent with its top rank by viscosity. It is generally preferred over the matching SU-8 2050 grade (SU-8 2000 series) when a thick, high-aspect-ratio process suffers adhesion loss or stress cracking, since the 3000 line was reformulated specifically to reduce both. Softbake time, PEB time, and develop time are all published as THICKNESS-BINNED ranges common to the whole 3000 series (not per-grade single values); because this recipe's spin curve is now digitized and falls entirely within the datasheet's 40-100 µm bracket, midpoint values from that bracket are recorded for those three fields (with the full bracket table quoted in each field's own notes), whereas exposure dose is left null because the datasheet does not explicitly attribute Table 3's doses to a single wavelength. As with the rest of the SU-8 family, fully cross-linked SU-8 3050 is notoriously difficult to strip: MicroChem's Remover PG only lifts minimally-crosslinked resist (or fully-crosslinked resist sitting over a sacrificial OmniCoat layer); a hard-baked film with no OmniCoat underneath requires piranha etch, plasma ashing, RIE, laser ablation, or pyrolysis to remove.

—07 / Family

Grades in this family

Other grades in the SU-8 3000 series line differ mainly in coating thickness:

SU-8 3000 series — grade comparison
GradeThicknessExposure dose
SU-8 3050 (this page)44.3–101.3 µm—
SU-8 3025——
—08 / 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 2026-07-22.

Cite this recipe

NANYTE. "SU-8 3050 process recipe." NANYTE Photoresist Library. https://nanyte.com/photoresists/su-8-3050. Accessed 2026-07-22.

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