https://nanyte.com/photoresists/su-8-2025 · last updated 2026-07-26
- Manufacturer
- MicroChem
- Tone
- negative
- Chemistry
- Epoxy (SU-8 type)
- Thickness
- 21.7–79.2 µm
- Developer
- SU-8 Developer (MicroChem)
- Applications
- High aspect ratio · MEMS structural · Electroplating / molding
Cross-checked — two independent extractions agree on the spin curve and the single-value figures.
- Substrate
- Resist
- Exposed
Spin coating
Data points
| Series | rpm | µm | Published dose |
|---|---|---|---|
| SU-8 2025 | 1000 | 79 | 150–215 mJ/cm² · 45–80 µm row 215–240 mJ/cm² · 85–110 µm row within 10 % of a bracket edge |
| 2000 | 41 | — | |
| 3000 | 28 | 150–160 mJ/cm² · 25–40 µm row | |
| 4000 | 22 | — |
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 "SU-8 2000 Spin Speed versus Thickness", p.2 of MicroChem "SU-8 2000 Permanent Epoxy Negative Photoresist Processing Guidelines for SU-8 2025, SU-8 2035, SU-8 2050 and SU-8 2075" (AMOLF mirror). The chart plots four curves (SU-8 2075/circle, 2050/triangle, 2035/diamond, 2025/square), each with only 4 markers at 1000/2000/3000/4000 rpm. SU-8 2025 is the square-marker series and the lowest (thinnest-film) of the four at every rpm, consistent with its legend position (listed last: 2075, 2050, 2035, 2025) and Table 1's viscosity ordering (2025 = 4500 cSt, the lowest of the four, so it coats thinnest at a given speed). No numeric table accompanies the figure.
- Recommended program (same for all grades in this document): dispense 1 ml of resist per inch (25 mm) of substrate diameter
- spin at 500 rpm for 5-10 s at 100 rpm/s acceleration, then spin at the target speed (per Figure 1) for 30 s at 300 rpm/s acceleration.
- Edge bead removal (EBR) with MicroChem's EBR PG solvent stream at the wafer edge is recommended before soft bake, both to limit hotplate contamination and to let the photomask reach close contact with the wafer.
SOURCE: "Coat" / "Recommended Program" / "Edge Bead Removal (EBR)", p.2.
- Adhesion
- HMDS not required — "Adhesion promoters are typically not required." HMDS pretreatment (MCC Primer 80/20) is recommended only "for applications that include electroplating."1
Soft bake
- Soft bake
- Not published — characterize on-tool
- Notes
- Published only as a THICKNESS-BINNED table shared by all four grades covered in this document (SU-8 2025/2035/2050/2075), not a single value per grade: 25-40 µm → 0-3 min @65°C then 5-6 min @95°C; 45-80 µm → 0-3 min @65°C then 6-9 min @95°C; 85-110 µm → 5 min @65°C then 10-20 min @95°C; 115-150 µm → 5 min @65°C then 20-30 min @95°C; 160-225 µm → 7 min @65°C then 30-45 min @95°C. SU-8 2025's own spin curve spans roughly 22-80 µm (1000-4000 rpm), i.e. mostly the 25-40 and 45-80 µm bins.
SOURCE: Table 2 "Soft Bake Times", p.2 of the MicroChem SU-8 2000 (2025-2075) Processing Guidelines
Exposure dose
SU-8 2025'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 dose table starts at 25 µm, above where SU-8 2025's own spin range begins at 21.7 µm.
| Film thickness | Dose |
|---|---|
| 25–40 µm | 150–160 mJ/cm² |
| 45–80 µm | 150–215 mJ/cm² |
| 85–110 µm | 215–240 mJ/cm² |
| 115–150 µm | 240–260 mJ/cm² |
| 160–225 µm | 260–350 mJ/cm² |
SOURCE: SU-8 2000 (2025-2075) Processing Guidelines
Table 3 'Exposure Dose' of the MicroChem SU-8 2000 (2025-2075) Processing Guidelines — one table indexed by film thickness, shared by SU-8 2025, 2035, 2050 and 2075. 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)
- Method
- immersion
- Rinse
- IPA
- Developer family
- Solvent
Not published for this resist: Dilution, Time — characterize on-tool.
SOURCE: "Development" and "Rinse and Dry" sections plus Table 6 "Development Times for SU-8 Developer", p.3-4
Hard bake, etch & strip
- Hard bake
- 150–250 °C · 5–30 min
- Stripper
- MicroChem Remover PG swells and lifts only minimally cross-linked SU-8 2000.2
- Storage
- Store upright in tightly closed containers, cool and dry, away from direct sunlight, at 40-70°F (4-21°C); away from light, acids, heat, and ignition sources.3
Not published for this resist: Descum, Etch resistance — characterize on-tool.
SOURCE: "Hard Bake (cure)" section, p.4
Where it's used
Practical notes from the datasheet
SU-8 2025 is the lowest-viscosity grade covered by this processing document (4500 cSt vs. up to 22,000 cSt for SU-8 2075) and spin-coats to roughly 20-80 µm depending on speed. Pick 2025 when your target film sits in the low tens of microns and you want the shortest bakes and best feature fidelity the 2000 family offers at that thickness; step up to SU-8 2050 or 2100 for progressively thicker single coats. Like every SU-8 2000 grade, it cross-links in two stages — exposure generates acid, and the post-exposure bake thermally drives the epoxy cross-linking — so PEB is a required processing step, not an optional cure. Soft-bake, PEB, dose and develop times are published only as thickness-binned ranges shared across the whole 2025-2075 family; treat the low end of the matching bin as a starting point and use the datasheet's cool-down/re-heat 'wrinkle' test to confirm the soft bake is complete. Once fully cross-linked, SU-8 is notoriously hard to strip: plain solvent remover only works on minimally exposed/baked film, and a hard-baked structure needs either a sacrificial OmniCoat layer beneath it or an oxidizing strip (piranha, plasma ash, RIE, laser ablation, pyrolysis) to remove. Edge bead removal before soft bake is recommended for every grade in this series to keep the photomask in close contact with the wafer and preserve resolution and aspect ratio in thick films.
Grades in this family
Other grades in the SU-8 2000 series line differ mainly in coating thickness:
Troubleshooting
Common failure modes for SU-8 2025, 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.
What is the exposure dose for SU-8 2025?
The datasheet publishes dose by film thickness, not per grade. SU-8 2025 coats roughly 22–80 µm, so its dose falls in the 150–160 mJ/cm² (25–40 µm) and 150–215 mJ/cm² (45–80 µm) bins. i-line (365 nm) is the recommended wavelength, though conventional UV (350–400 nm) is also used. Multiply by ~1.5× on glass/ITO and 1.5–2× on most metals versus silicon. No separate 405 nm (h-line) dose is published — characterize on-tool.
SOURCE: SU-8 2000 (2025–2075) Processing Guidelines
MicroChem SU-8 2000 (2025–2075) Processing Guidelines — Table 3 exposure dose + p.1 wavelength statement; substrate multipliers Table 4
Does SU-8 2025 need a post-exposure bake, and why?
Yes — PEB is a required step, not an optional cure. SU-8 cross-links in two stages: exposure generates photoacid, and the post-exposure bake thermally drives the epoxy cross-linking. Times are thickness-binned; for SU-8 2025's ~22–80 µm range they run about 1 min at 65°C (optional stress-reduction step) then 5–7 min at 95°C. A latent mask image should be visible after ~1 min at 95°C; if not, exposure or heating was insufficient.
SOURCE: MicroChem SU-8 2000 (2025–2075) Processing Guidelines — Table 5 Post Exposure Bake Times, p.3
What soft bake does SU-8 2025 need?
Soft-bake times are published per thickness bin, shared across the SU-8 2025–2075 grades. For SU-8 2025's typical films: 25–40 µm → 0–3 min at 65°C then 5–6 min at 95°C; 45–80 µm → 0–3 min at 65°C then 6–9 min at 95°C. Use a level hotplate — convection ovens are not recommended (a skin can trap solvent). Cool the wafer then reheat; if the film wrinkles, bake longer and repeat until wrinkles disappear.
SOURCE: MicroChem SU-8 2000 (2025–2075) Processing Guidelines — Table 2 Soft Bake Times, p.2
Which developer does SU-8 2025 use?
SU-8 Developer (MicroChem), used undiluted by immersion, spray, or spray-puddle (ethyl lactate and diacetone alcohol also work). Immersion times are thickness-binned: 25–40 µm → 4–5 min; 45–75 µm → 5–7 min. Rinse ~10 s with fresh developer, then ~10 s IPA, then dry with filtered N2. A white film after the IPA rinse means underdevelopment — repeat the develop-and-rinse cycle rather than relying on IPA to finish.
SOURCE: MicroChem SU-8 2000 (2025–2075) Processing Guidelines — Development / Rinse and Dry + Table 6, p.3–4
Why is my SU-8 2025 cracking after development?
Surface cracks after development come from film stress. The datasheet recommends a short 150°C bake for a couple of minutes (all thicknesses) specifically to anneal cracks seen after development. A full hard bake is otherwise optional and only needed if the device will see thermal processing in use — typically 150–250°C for 5–30 min, at roughly 10°C above the maximum expected operating temperature.
SOURCE: MicroChem SU-8 2000 (2025–2075) Processing Guidelines — Hard Bake (cure) section, p.4
Sources & disclaimer
- MicroChem — SU-8 2025 datasheet (No revision/date string is printed in the document body (a 5-page processing-guidelines PDF with no header/footer revision code). The mirror's filename indicates 'Ver4'.) · accessed 2026-07-10
- "Substrate Preparation", p.2.
- "Removal" / "Plasma Removal", p.5.
- "Storage", p.5.
- 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 2026-07-26.