https://nanyte.com/photoresists/az-125nxt · last updated 2026-07-26
- Manufacturer
- Merck
- Tone
- negative
- Chemistry
- Photopolymer
- Thickness
- 18–120 µm
- Developer
- AZ 300MIF
- Applications
- Etch mask · Electroplating / molding · High aspect ratio
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 |
|---|---|---|
| AZ 125nXT-10B | 600 | 120 |
| 800 | 100 | |
| 1000 | 75 | |
| 1500 | 55 | |
| 1900 | 48 | |
| 2100 | 43 | |
| 2500 | 38 | |
| AZ 125nXT-7B | 600 | 57 |
| 1000 | 35 | |
| 1300 | 24 | |
| 1500 | 21 | |
| 1900 | 18 | |
| 2300 | 14 |
Values are the manufacturer’s starting points, not a guarantee — characterize on your own tool. Series digitized from a published figure are approximate (±10 %).
AZ 125nXT-10B: read from figure, p.10 of AZ 125nXT Series Technical Datasheet (Merck, Rev. 01/24), 'COATING GUIDELINES' spin-speed chart. Two-grade chart; traces identified by the chart's own legend (filled triangle = AZ 125nXT-10B, filled circle = AZ 125nXT-7B), not by color alone.
AZ 125nXT-7B: read from figure, p.10 of AZ 125nXT Series Technical Datasheet (Merck, Rev. 01/24), 'COATING GUIDELINES' spin-speed chart. Two-grade chart; traces identified by the chart's own legend (filled triangle = AZ 125nXT-10B, filled circle = AZ 125nXT-7B), not by color alone.
- The datasheet explicitly cautions (p.10) that, unlike thin-resist spin curves, 'films will continue to thin with extended spin times' for a resist this viscous, and that the plotted curves 'may be used as general guidelines for coating films of 30µm thickness and above' - i.e. the document itself flags the low-thickness end of its own chart as unreliable.
- That caveat is directly visible in the data: my read of the AZ 125nXT-7B trace extends from ~57 µm (600 rpm) down to ~14 µm (2300 rpm), both outside the grade's own stated 18-35 µm range (p.2 THICKNESS GRADES table) - an internal inconsistency a QC reviewer should note, not something I resolved.
- A full example coating sequence with acceleration and function-per-step (dispense/spread/snap-spin/set-thickness/backside rinse-dry/edge-bead-flatten) is given on p.10 for building a real recipe, rather than a single spin-speed number.
- Adhesion
- HMDS recommended — 'Oxide forming substrates (Si, etc.) should be HMDS primed prior to coating AZ 125nXT.
- Rehydration
- None required - the datasheet states explicitly, in both the Typical Process summary ('Rehydration Hold: None', p.1) and in bold in the Process Considerations section ('NO POST BAKE REHYDRATION DELAYS ARE REQUIRED', p.11), that no rehydration hold is needed, unlike thick DNQ resists.
Soft bake
- Soft bake
- 115–140 °C · 5–20 min
- Notes
- Soft-bake conditions are 115-140°C for 5-20 min, and the time scales with film thickness.
SOURCE: p.1, p.11 (range); pp.3-6 (worked-example values)
Exposure dose
Sensitivity spans 365 to 435 nm with no single stated dose, and the tool matters as much as the film: one 20 µm coat took 1120 mJ/cm² on a Suss MA-200 and 2000 mJ/cm² on an Ultratech AP300; a 70 µm film took 1800 mJ/cm². 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.
Development
- Developer
- AZ 300MIF
- Dilution
- 0.26N (2.38%) TMAH, ready-to-use; puddle mode recommended
- Method
- puddle
- Developer family
- TMAH-based
Not published for this resist: Time, Rinse — characterize on-tool.
SOURCE: p.1, p.11 (developer/mode); pp.3-6 (worked-example times)
Hard bake, etch & strip
- Hard bake
- 130–140 °C
- Etch resistance
- Described only qualitatively: 'etch resistance, chemical resistance, and thermal stability far superior to typical chemically amplified photoresists' (p.1) and 'RIE etch applications' (p.1).
- Stripper
- AZ 400T, 75°C, 20-25 min with agitation (p.11, Stripping); corroborated by worked electroplating examples: 'Strip: AZ 400T @ 75C' for Cu (p.7) and 'Photoresist Strip AZ 400T @ 75°C' for Au (p.8)
Not published for this resist: Descum, Storage — characterize on-tool.
SOURCE: p.11 (Hard Bake)
Where it's used
Practical notes from the datasheet
AZ 125nXT is a photopolymer (not conventional DNQ or the vendor's own 'typical' CAR) negative resist purpose-built for ultra-thick, high-aspect-ratio plating molds and RIE masks up to and beyond 100 µm in a single coat. Two properties make it distinct from thinner thick-film resists: no rehydration hold is needed after softbake, and a PEB is explicitly not required at all - both are called out in bold in the datasheet, in direct contrast to the classic DNQ rehydration wait this recipe library flags elsewhere. Real electroplating results are documented for Cu, Ni-compatible, and Au processes with post-plate/post-strip micrographs (pp.7-8), and the stripped resist shows no reported underplating. Coating this resist is its own discipline: the vendor explicitly warns that, unlike thin-resist spin coating, films keep thinning with extended spin time, so both spin speed and spin time must be tuned together (p.10), and the datasheet's own coating-guideline curves are only endorsed for films of 30 µm and above even though they are plotted further down. HMDS priming is required on oxide-forming substrates such as Si.
Sources & disclaimer
- Merck — AZ 125nXT datasheet (Rev. (01/24)) · accessed 2026-07-10
- Staab et al.. Applications of Novel High-Aspect-Ratio Ultrathick UV Photoresist for Microelectroplating. Journal of Microelectromechanical Systems (2011). doi:10.1109/jmems.2011.2159098The acrylic resist AZ 125 nXT is demonstrated at 400, 800 and 1400 um film thickness with 20:1 aspect ratio for low-cost UV-LIGA, electroformed in acid copper at room temperature and near-neutral nickel at 50 C, then stripped in DMSO/acetone or plasma to release freestanding metal at 13:1 and 16:1.
- Knoll et al.. Fabrication of microfluidic chips using lithographic patterning and adhesive bonding of the thick negative photoresist AZ 125 nXT. Proceedings of SPIE (2015). doi:10.1117/12.2178812AZ 125 nXT was lithographically patterned into 90 um deep microfluidic channels and sealed by adhesive bonding, presented as an SU-8 alternative that fully cross-links during UV exposure without a post-exposure bake.
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.