https://nanyte.com/photoresists/su-8-3025 · last updated 2026-09-28
- Manufacturer
- Kayaku MicroChem / MicroChem Corp.
- Tone
- negative
- Chemistry
- Epoxy (SU-8 type)
- Thickness
- 23–58 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
- Substrate
- Resist
- Exposed
Spin coating
Data points
| Series | rpm | µm | Published dose |
|---|---|---|---|
| SU-8 3025 | 1000 | 58 | 150–250 mJ/cm² · 40–80 µm rows (2) |
| 2000 | 37 | 150–250 mJ/cm² · 30–50 µm rows (2) | |
| 3000 | 25 | 150–250 mJ/cm² · 20–50 µm row | |
| 4000 | 23 | 150–250 mJ/cm² · 20–50 µm row |
Values are the manufacturer’s starting points, not a guarantee — characterize on your own tool. Series digitized from a published figure are approximate (±10 %).
Published dose is the datasheet’s own thickness bracket, quoted as printed — the full table and its citation are in the exposure section. A thickness the table does not cover shows nothing, and a thickness within 10 % of a bracket edge shows every bracket it could fall in.
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 (no printed revision code). The 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. SU-8 3025 is the filled-diamond series, 3rd from the top of five at every rpm, consistent with its legend position (3rd of 3050/3035/3025/3010/3005) and Table 1's viscosity ordering (3025 = 4400 cSt, the middle of the five grades). No numeric per-rpm table exists for SU-8 3025 alone in this datasheet — Tables 2/3/5/6 are thickness-binned ranges shared across the whole 3000 series, not per-grade spin data.
- 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 3025 thickness should be read from Figure 1 ('Spin speed vs. Thickness for SU-8 3000 resists', 21°C US & EU, p.1) or Figure 2 (23°C Japan & Asia, p.2), each of which plots all five grades (3005/3010/3025/3035/3050) as separate traces vs. 1000-5000 rpm with NO accompanying numeric table.
- Figure 1 (21°C US & EU) is the curve plotted above; the SU-8 3025 trace is the filled-diamond series, 3rd from the top of five, consistent with its legend position and Table 1's viscosity ordering (3025 = 4400 cSt, the middle of the five grades).
- Figure 2 (23°C Japan & Asia) is not shown here.
- No numeric table exists for SU-8 3025 alone — Table 1 (p.2) only ranks the five grades by viscosity.
- 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).
Soft bake
- Soft bake
- 95 °C · 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. No single soft-bake time is quoted here, because the row that applies depends on the film thickness actually coated. 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…
Table 2 'Soft Bake Times', p.2 of SU-8 3000 Permanent Epoxy Negative Photoresist datasheet, Kayaku MicroChem/MicroChem Corp.
Exposure dose
SU-8 3025's dose is published against film thickness, not as a single number. Read the row for the film you coat and run a dose array around it.
- As published
- The bins overlap here, so a mid-range film matches more than one: 100–200 mJ/cm² for 4–10 µm, 125–200 mJ/cm² at 8–15 µm, and a flat 150–250 mJ/cm² across every bracket from 20 to 100 µm.
- Post-exposure bake
- 95 °C
| Film thickness | Dose |
|---|---|
| 4–10 µm | 100–200 mJ/cm² |
| 8–15 µm | 125–200 mJ/cm² |
| 20–50 µm | 150–250 mJ/cm² |
| 30–80 µm | 150–250 mJ/cm² |
| 40–100 µm | 150–250 mJ/cm² |
SOURCE: Table 3 'Exposure Dose', p.2 of the SU-8 3000 Permanent Epoxy…
Table 3 'Exposure Dose', p.2 of the SU-8 3000 Permanent Epoxy Negative Photoresist datasheet, Kayaku MicroChem/MicroChem Corp. Brackets are indexed by film thickness and overlap exactly as printed. Not attributed to a specific wavelength — the document recommends i-line but states conventional UV (350-400 nm) is most common.
Development
- Developer
- SU-8 Developer (MicroChem's proprietary solvent-based developer); ethyl lactate and diacetone alcohol are also stated to work
- 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, Time, Method — characterize on-tool.
SOURCE: Develop and Rinse-and-Dry sections, p.3 of SU-8 3000 Permanent…
Develop and Rinse-and-Dry sections, p.3 of SU-8 3000 Permanent Epoxy Negative Photoresist datasheet, Kayaku MicroChem/MicroChem Corp.
Hard bake, etch & strip
- Hard bake
- 150–200 °C (optional — for applications where the resist stays on the device)
- Descum
- Not published — characterize on-tool
- 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.
SOURCE: Hard Bake (cure) section, p.3 of SU-8 3000 Permanent Epoxy…
Hard Bake (cure) section, p.3 of SU-8 3000 Permanent Epoxy Negative Photoresist datasheet, Kayaku MicroChem/MicroChem Corp.
Where it's used
Practical notes from the datasheet
SU-8 3025 is the third-lowest-viscosity member (4,400 cSt, 72.3% solids) 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 mid-viscosity option — thicker-coating than 3005 and 3010, thinner than 3035 and 3050 — and it is generally preferred over the matching SU-8 2000 grades when a process suffers adhesion loss or stress cracking, since the 3000 line was reformulated specifically to reduce both. Figures 1-2 plot all five grades' film thickness against 1000-5000 rpm spin speed on one shared axis with no accompanying numeric table, and the five traces are separable only by viscosity ranking, consistent with SU-8 3025 being the middle grade by viscosity. Softbake time, PEB time, exposure dose, and develop time are all published as THICKNESS-BINNED ranges common to the whole 3000 series (not per-grade single values), so no single number is quoted for any of them and the full bracket table is printed with each step instead — reporting one number would be false precision without first knowing which bracket a real SU-8 3025 process actually lands in. As with the rest of the SU-8 family, fully cross-linked SU-8 3025 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.
Grades in this family
Other grades in the SU-8 3000 series line differ mainly in coating thickness:
| Grade | Thickness |
|---|---|
| SU-8 3025 (this page) | 23–58 µm |
| SU-8 3050 | 44.3–101.3 µm |
Troubleshooting
Common failure modes for SU-8 3025, answered from the manufacturer's datasheet and application notes. These are starting points — your substrate, tooling and environment shift the specifics, so calibrate on-tool.
My SU-8 3025 turns milky white during the IPA rinse. What went wrong?
The substrate is underdeveloped. The datasheet's rinse is a ~10 s spray of fresh SU-8 developer followed by a ~10 s IPA spray, and a white film in the IPA step means unexposed resist is still there. Immerse or spray with SU-8 developer again to finish the job, then repeat the rinse. SU-8 3025 films sit mostly in the 20–50 µm (5–8 min) and 30–80 µm (6–12 min) develop rows; those times are approximate and shift with agitation, so thick or high-aspect-ratio parts need strong agitation.
SOURCE: Kayaku MicroChem SU-8 3000 datasheet (no revision printed) — Develop, Table 6 and Rinse and Dry note, p.3
My SU-8 3025 film doesn't match the spin chart. Am I reading the right curve?
Check which chart you used. The SU-8 3000 sheet prints two spin curves: Figure 1 for 21 °C (US & EU) and Figure 2 for 23 °C (Japan & Asia), and they differ noticeably — SU-8 3025 reads roughly 58 µm at 1000 rpm on Figure 1 but roughly 68 µm on Figure 2, with the gap narrowing at higher speeds. Pick the chart matching your region's material and lab temperature, then measure; the recommended program is a 500 rpm spread followed by 30 s at the final speed.
SOURCE: Kayaku MicroChem SU-8 3000 datasheet (no revision printed) — Coat, Recommended Program and Figure 1, p.1; Figure 2, p.2
The SU-8 3025 bake and dose tables have overlapping rows. Which do I follow?
The rows overlap as printed — 20–50, 30–80 and 40–100 µm — so a 35 µm SU-8 3025 film matches two of them. Soft bake at 95 °C is 10–15 min (20–50 µm) or 10–30 min (30–80 µm); exposure is 150–250 mJ/cm² in both; PEB is 3–5 min at 95 °C, with an optional 1 min at 65 °C first for stress reduction. Start at the short end and let the film decide: no wrinkles after a cool-down and re-heat, and a mask image visible after 1 min of PEB.
SOURCE: MicroChem SU-8 3000 datasheet
Kayaku MicroChem SU-8 3000 datasheet (no revision printed) — Table 2 Soft Bake Times, soft bake note and Table 3 Exposure Dose, p.2; Table 5 and PEB note, p.3
Do I need a primer for SU-8 3025 as a plating mould?
Only for plating. SU-8 3000 was formulated for improved adhesion, and on a clean, dry substrate — piranha clean and DI rinse, or RIE / O₂ barrel ashing — adhesion promoters are typically not required. For electroplating, the datasheet recommends pretreating with MCC Primer 80/20 (HMDS). Plating seed metals such as gold, copper and nickel also need 1.5–2X the silicon exposure dose.
SOURCE: MicroChem SU-8 3000 datasheet
Kayaku MicroChem SU-8 3000 datasheet (no revision printed) — description and Substrate Preparation, p.1; Table 4 Exposure Doses for Substrates, p.2
Sources & disclaimer
- Kayaku MicroChem / MicroChem Corp. — SU-8 3025 datasheet · accessed 2026-07-10
- Shaw et al.. Negative photoresists for optical lithography. IBM Journal of Research and Development (1997). doi:10.1147/rd.411.0081The IBM origin paper for the EPON-based epoxy negative resist that became SU-8, describing its formulation and use as a thick optical-lithography resist.
- Lorenz et al.. SU-8: a low-cost negative resist for MEMS. Journal of Micromechanics and Microengineering (1997). doi:10.1088/0960-1317/7/3/010Established SU-8 as a MEMS structural resist, producing thick high-aspect-ratio structures by near-UV lithography.
- del Campo, Greiner. SU-8: a photoresist for high-aspect-ratio and 3D submicron lithography. Journal of Micromechanics and Microengineering (2007). doi:10.1088/0960-1317/17/6/R01Widely cited review of SU-8 processing (coat, bake, expose, develop) for high-aspect-ratio and 3D microstructures across the SU-8 family.
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 2026-09-28.