https://nanyte.com/photoresists/az-p4903 · last updated 2026-09-28
- Manufacturer
- Merck KGaA (AZ Electronic Materials)
- Tone
- positive
- Chemistry
- DNQ-novolak
- Thickness
- 10–30 µm
- Developer
- AZ 400K 1:3 or AZ 421K (unbuffered) for films above 12 µm; AZ 400K 1:4 for thinner (10-12 µm) films only; AZ Developer 1:1 where aluminium must not be etched; AZ 340 is also listed
- Applications
- Electroplating / molding · Etch mask
- Substrate
- Resist
- Exposed
Spin coating
The manufacturer does not publish a spin curve for AZ P4903.
- No spin curve is published for this grade — the chart on p.2 covers only P4110, P4210, P4330 and P4400.
- Films this thick are not spun to equilibrium; the sheet gives an example coating sequence for films above 20 µm on p.5: low-speed spin at 500 rpm for 4 s, dispense at rest for 5 s, spread at 300 rpm for 3-5 s, a cast spin whose time and speed depend on the target thickness, then edge-bead removal at 400 rpm for 20 s and a 10 s dry at 400 rpm, with accelerations of 20-50 krpm/s.
- For the cast-spin settings the sheet refers you to the AZ representative.
- Adhesion
- HMDS recommended — 'Substrates must be clean, dry, and free of organic residues. Oxide forming substrates (Si, etc.) should be HMDS primed prior to coating AZ P4000' (Substrate preparation, p.6). A soft bake towards 115 °C also improves adhesion to most metals.
- Rehydration
- Required for films thicker than 4.0 µm: hold between soft bake and exposure for typically 30-60 minutes, depending on film thickness, at 40-45 % relative humidity (Film rehydration, p.6). The p.3 reference process for a 12 µm AZ P4620 film uses a 30 min hold at 42 % RH.
Soft bake
- Soft bake
- 95–115 °C
- Rehydrate
- 30–60 min (films over 4 µm, 40–45 % RH)
- Notes
- No time is published for this grade. The process-considerations page gives 95-115 °C and calls bake conditions application specific; the typical-process box on p.1 prints the window as 90-115 °C, so the two pages differ by 5 °C at the low end, and the narrower one is carried. Temperatures towards 115 °C improve adhesion to most metals, and thicker films may need a ramped bake to stop solvent outgassing from raising bubbles.
SOURCE: Soft bake section, p.6, and typical process box, p.1, of the AZ P4000 Series technical datasheet, Rev. (08/21)
SOURCE: Film Rehydration, p.6 of the AZ P4000 Series technical…
Film Rehydration, p.6 of the AZ P4000 Series technical datasheet: "P4000 photoresist films thicker than 4.0µm require a rehydration hold between soft bake and exposure. Hold times are typically 30-60 minutes (depending upon film thickness) @ relative humidity 40-45%."
Exposure dose
AZ P4903'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
- No dose is given for AZ P4903 by name. The series table gives approximate Suss MA-200 aligner doses by film thickness: 90 mJ/cm² at 1.5 µm, 135 mJ/cm² at 3.5 µm and 800 mJ/cm² at 12 µm.
| Film thickness | Dose |
|---|---|
| 1.5 µm | 90 mJ/cm² |
| 3.5 µm | 135 mJ/cm² |
| 12 µm | 800 mJ/cm² |
SOURCE: 'Approximate exposure dose requirement vs. film thickness…
'Approximate exposure dose requirement vs. film thickness (Suss MA-200)' table, p.5 of the AZ P4000 Series technical datasheet, Rev. (08/21): 1.5 µm 90 mJ/cm², 3.5 µm 135 mJ/cm², 12 µm 800 mJ/cm². The table is published for the P4000 series as a whole, indexed by film thickness rather than by grade.
Development
- Developer
- AZ 400K 1:3 or AZ 421K (unbuffered) for films above 12 µm; AZ 400K 1:4 for thinner (10-12 µm) films only; AZ Developer 1:1 where aluminium must not be etched; AZ 340 is also listed
- Dilution
- AZ 400K 1:3 (or AZ 421K, unbuffered) for films above 12 µm — most of this grade's 10->30 µm range; AZ 400K 1:4 for better selectivity on thinner 10-12 µm films only; AZ Developer 1:1
- Method
- spray or immersion
- Developer family
- Buffered alkaline
Not published for this resist: Time, Rinse — characterize on-tool.
SOURCE: Developing section, p.6, and companion products, p.1, of the AZ P4000 Series technical datasheet, Rev. (08/21)
Hard bake, etch & strip
- Hard bake
- 100–110 °C
- Etch resistance
- 'Excellent substrate adhesion for wet etch applications' (p.1); a 100-110 °C hard bake 'improves adhesion in wet etch or plating applications and improves pattern stability in dry etch processes' (p.6).
- Stripper
- AZ 300T, AZ 400T or AZ Kwik Strip (companion products, p.1).
Not published for this resist: Descum, Storage — characterize on-tool.
SOURCE: Hard bake section, p.6, and dielectric insulator table, p.5, of the AZ P4000 Series technical datasheet, Rev. (08/21)
Where it's used
Practical notes from the datasheet
AZ P4903 is the most viscous P4000 grade (1650 cSt at 23 °C, three times AZ P4620) and the one for the tallest single-coat plating moulds, rated from 10 µm to beyond 30 µm. The sheet is candid that this range is reached with special coating programs rather than a spin curve, and it publishes the skeleton of one: a slow spread, a thickness-specific cast spin, and edge-bead removal at 400 rpm. Everything about processing gets slower at this thickness. Soft bake may need a ramped temperature to stop solvent outgassing from raising bubbles, the 30-60 minute rehydration hold at 40-45 % RH scales with film thickness, and the dose climbs steeply — the series table already reads 800 mJ/cm² at 12 µm on a Suss MA-200. Develop in AZ 400K 1:3 or AZ 421K, which the sheet recommends above 12 µm.
Grades in this family
Other grades in the AZ P4000 Series line differ mainly in coating thickness:
| Grade | Thickness |
|---|---|
| AZ P4110 | 1–3 µm |
| AZ P4210 | 2–4 µm |
| AZ P4330-RS | 3–5 µm |
| AZ P4400 | 4–6 µm |
| AZ P4620 | 6–20 µm |
| AZ P4903 (this page) | 10–30 µm |
Troubleshooting
Common failure modes for AZ P4903, 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.
Why can't I hit a target AZ P4903 thickness by picking a spin speed?
At these thicknesses the film is never spun to equilibrium. The datasheet says single films above 7.0 µm are not spun to equilibrium, and thicker coats need special programs with carefully timed spread and spin cycles; its spin curves stop at AZ P4400, so AZ P4903 (10.0 to >30 µm) has none. Its example sequence for 20+ µm films: 500 rpm for 4 s, dispense 5 s at rest, spread 3–5 s at 300 rpm, a cast spin whose time and speed depend on target thickness, then 20 s edge-bead removal and a 10 s dry, both at 400 rpm.
SOURCE: AZ P4000 Series Technical datasheet (Merck, Rev. 08/21) —…
AZ P4000 Series Technical datasheet (Merck, Rev. 08/21) — Thickness Grades, p.1; Typical Spin Curves note, p.2; Example Coating Sequence for 20+ µm Thick Films, p.5; Coating, p.6
Freshly opened AZ P4903 gives bubbly, streaky coats — how long should it sit?
Longer than a thin resist. Over months the photoactive compound releases N2 that dissolves in the resist and comes out as bubbles once the bottle is opened; for very high-viscosity resists MicroChemicals allows a few hours or even 1–2 days before dispensing, with the cap set loosely for pressure balance. AZ P4903 is the most viscous grade in the series at 1650 cSt, against 536 cSt for the next grade down. If the dispense line is pushed with nitrogen, that is another N2 source.
SOURCE: MicroChemicals 'Photolithography Trouble Shooter' application…
MicroChemicals 'Photolithography Trouble Shooter' application note — Bubbles and Comet-Like Structures after Spin Coating (Nitrogen Bubbles), p.2; Bubbles or Particles in Resist Film After Coating, p.13–14. AZ P4000 Series Technical datasheet (Merck, Rev. 08/21) — AZ P4000 Series Fluid Viscosities, p.5
My AZ P4903 film blisters during soft bake — what should I change?
Ramp the temperature. The datasheet says thick P4000 films may require a gradual ramp of the soft bake to prevent bubbling, and that thicker films may need a ramped process to avoid bubbles from rapid solvent outgassing; the soft-bake range is 95–115 °C. MicroChemicals adds that, for thick or solvent-rich coats, a delay with the wafer lying horizontal between coating and soft bake keeps the edge bead from growing as heat lowers the resist's viscosity.
SOURCE: AZ P4000 Series Technical datasheet (Merck, Rev. 08/21) —…
AZ P4000 Series Technical datasheet (Merck, Rev. 08/21) — Reference Process footnote, p.3; Soft Bake, p.6. MicroChemicals 'Photolithography Trouble Shooter' application note — Spin Coating: Edge Bead? (Delay between Coating and Softbake), p.3
Is a 60-minute rehydration hold enough for a 30 µm AZ P4903 film?
Possibly not. The datasheet requires a hold for any P4000 film over 4.0 µm and gives typically 30–60 min depending on thickness, at 40–45 % relative humidity. MicroChemicals' guidance is that rehydration time rises from about 1 min at 1 µm to several hours for films beyond 30 µm, and that development rate drops significantly below about 40 % RH. At the top of AZ P4903's range, treat 60 min as a minimum and check the bottom of the film clears before shortening develop or raising dose.
SOURCE: AZ P4000 Series Technical datasheet (Merck, Rev. 08/21) — Film…
AZ P4000 Series Technical datasheet (Merck, Rev. 08/21) — Film Rehydration, p.6; Thickness Grades, p.1. MicroChemicals 'Photolithography Trouble Shooter' application note — Development: Insufficient Development Rate (Sufficient Rehydration?), p.6
Which developer strength suits AZ P4903?
The stronger one. The datasheet recommends AZ 400K 1:3 or the unbuffered AZ 421K for films above 12 µm, keeping AZ 400K 1:4 for thinner films where its selectivity matters — AZ P4903's range starts at 10 µm and runs past 30 µm. MicroChemicals notes that for thick-resist processing developer concentration can be raised by some 10 %, at the cost of selectivity, since dark erosion grows faster than development rate as concentration rises.
SOURCE: AZ P4000 Series Technical datasheet (Merck, Rev. 08/21) —…
AZ P4000 Series Technical datasheet (Merck, Rev. 08/21) — Developing, p.6; Thickness Grades, p.1. MicroChemicals 'Photolithography Trouble Shooter' application note — Development: Dark Erosion Too High (Proper Developer Dilution?), p.9
Sources & disclaimer
- Merck KGaA (AZ Electronic Materials) — AZ P4903 datasheet (Rev. (08/21)) · accessed 2026-09-10
- https://www.microchemicals.com/dokumente/datenblaetter/tds/merck/en/tds_az_p4620_photoresist.pdf — AZ P4620 Photoresist Data Package, 'Thick Photoresist Product Summary' (p.3): the table lists the 'P4000 Series' row with Platform 'DNQ' — the basis for classifying AZ P4903 as dnq-novolak.
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.