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AR-U 4030 process recipe

AR-U 4030 is Allresist's image-reversal photoresist in the AR-U 4000 series, a novolac/bisazide negative formulation that can also be run as an ordinary positive resist, coating roughly 1.8-2.5 µm and producing pronounced undercut lift-off profiles when processed with an image-reversal bake plus flood exposure.

https://nanyte.com/photoresists/ar-u-4030 · last updated 2026-07-26

At a glance
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Manufacturer
Allresist
Tone
image reversal
Chemistry
Bisazide-novolak
Thickness
1.8–2.5 µm
Exposure dose
42 mJ/cm²
Developer
AR 300-35
Applications
Image reversal · Lift-off · Etch mask

Cross-checked — two independent extractions agree on the spin curve and the single-value figures.

The reversal bake fixes the exposed pattern and the flood exposure makes everything else soluble, so the developed image is inverted — typically with an undercut sidewall. Schematic cross-sections for AR-U 4030 — feature width, film aspect ratio and sidewall angle are illustrative, not to scale.
01 / Coating

Spin coating

Spin curve for AR-U 4030: film thickness in µm against spin speed in rpm.123451k2k3k4k5k6kSPIN SPEED (rpm)THICKNESS (µm)
Data points
AR-U 4030 — film thickness (µm) by spin speed (rpm)
Seriesrpmµm
AR-U 403010004.1
20002.9
30002.4
40002.1
50001.9
60001.8

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, 'Spin curve' (D₀/µm 0-6.0 vs rpm 0-8000), p.32 of Allresist AR-U 4000 product-information sheet (as of January 2017); multi-grade chart with three individually legended traces — AR-U 4030 (topmost, dark-navy diamonds), AR-U 4040 (middle, red squares), AR-U 4060 (bottom, olive triangles). The topmost trace is AR-U 4030 two ways: its marker colour matches the dark-navy 'AR-U 4030' legend label sitting at that trace's right-hand endpoint, and it sorts correctly against the Properties I table's per-grade nominal 'Film thickness/4000 rpm (µm)' row (AR-U 4030 = 1.8, AR-U 4040 = 1.4, AR-U 4060 = 0.6, p.32) and the Coating-box captions ('4000 rpm, 60 s, 1.8/1.4/0.6 µm', p.33/p.34) — the thickest plotted trace is the grade with the largest nominal thickness. Note a real disagreement inside the datasheet: the figure's own 4000 rpm marker reads 2.09 µm, ~16% above the printed 1.8 µm nominal in the Properties I table and the matching Coating-box captions. The figure is what this curve reports, since the table value is a rounded nominal rather than a reading off this measured curve.

Redrawn from the manufacturer's published data — hover to read between points, click to pin.
  • Spin-speed-vs-thickness figure ('Spin curve', p.32, axes D₀/µm 0-6.0 vs rpm 0-8000): genuine multi-grade chart, three individually legended traces (AR-U 4030 topmost/navy, AR-U 4040 middle/red, AR-U 4060 bottom/olive)
  • only the AR-U 4030 (topmost navy diamond) trace is plotted here, from its 6 markers between 1000-6000 rpm.
  • Trace identity is fixed by both the legend colour and the Properties I nominal-thickness ranking (4030=1.8 > 4040=1.4 > 4060=0.6 µm at 4000 rpm, matching the top>mid>bottom trace order).
  • The figure's own 4000 rpm marker (2.09 µm) is ~16% above the Properties I table's printed anchor (1.8 µm) — a genuine figure-vs-table disagreement in the source datasheet; the figure value is the one plotted here.
  • No dispense volume or acceleration ramp is described anywhere in this document.
Adhesion
HMDS not required — Datasheet specifies Allresist's own adhesion promoter AR 300-80 (Process chemicals table, p.32); does not mention HMDS specifically either way.
02 / Bake

Soft bake

Soft bake
90 °C · 60 s · hotplate
Notes
Referred to as 'Tempering' in the datasheet. ± 1 °C tolerance. Alternative: 85 °C, 25 min (1500 s) convection oven. Same schedule is used for both the positive-tone and negative/image-reversal processes. Corroborated by Processing instructions prose (p.35): for pure positive-tone use, 'a softbake at only 85 °C (oven) or 90 °C (hot plate) after coating is recommended... since this resist has the potential to be crosslinked due to its specific components.'

SOURCE: Process conditions diagrams, p.33 (positive) and p.34 (negative); Processing instructions, p.35

03 / Exposure

Exposure dose

The manufacturer publishes 42 mJ/cm². Dose scales with film thickness and depends on your optics, so treat it as a starting point and run a dose array.

As published
42 mJ/cm² is the image-wise dose for the reversal (negative-tone) process; the same resist run straight positive, with no reversal bake and no flood exposure, is published at 38 mJ/cm² instead.
Post-exposure bake
115 °C · 4 min
Flood exposure
74 mJ/cm²

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

SOURCE: Process conditions, NEGATIVE (image-reversal) process diagram…

Process conditions, NEGATIVE (image-reversal) process diagram, p.34 of Allresist AR-U 4000 series product information (English); dose stated as "Exposure dose (E0, broadband UV stepper): 42 mJ/cm²". The positive-process diagram on p.33 gives a different dose (38 mJ/cm²) and is deliberately not used.

04 / Development

Development

Developer
AR 300-35
Dilution
4:3
Time
60 s
Method
puddle
Rinse
DI-H2O, 30 s
Developer family
TMAH or buffered alkaline

SOURCE: Process conditions negative process diagram, p.34

05 / Post-processing

Hard bake, etch & strip

Etch resistance
No qualitative etch-resistance claim is made in the Characteristics list (unlike Allresist's AR-N 4300 sheet); only a raw rate table is given. Plasma etching rates (5 Pa, 240-250 V Bias, Properties II table, p.32): Ar-sputtering 8 nm/min, O2 169 nm/min, CF4 40 nm/min, 80% CF4 + 16% O2 89 nm/min.
Stripper
General Process chemicals table (p.32): AR 300-76, AR 300-72. Positive-process removal (p.33): 'AR 300-76 or O2 plasma ashing'. Negative-process removal (p.34): 'AR 300-70 or O2 plasma ashing' — this last figure ('AR 300-70') differs from the AR 300-76 used elsewhere in the same datasheet; reproduced verbatim as printed rather than corrected to 300-76, and flagged here for human verification against the source PDF, p.34, in case it is a distinct product or a transcription variant.
Storage
"Storage 6 month (°C): 8 - 12" (Properties I table, p.32).

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

SOURCE: Process conditions diagrams, p.33 (positive) and p.34 (negative)

06 / Applications

Where it's used

Practical notes from the datasheet

AR-U 4030 is Allresist's image-reversal resist in the AR-U 4000 series — described as a 'combination of novolac and bisazide' — that can be processed either as an ordinary positive resist or, with an image-reversal bake and flood exposure, as a negative resist with pronounced undercut lift-off profiles. In image-reversal (negative) mode the sequence is: image-wise broadband exposure (42 mJ/cm² for this grade) -> an 'image reversal bake' (115 °C/4 min hotplate, or 110 °C/25 min oven) that crosslinks the exposed areas via the resist's amine component -> an unmasked flood exposure (74 mJ/cm², roughly twice the image-wise dose) that renders the remaining, still-unexposed areas developable -> puddle development in AR 300-35 (4:3). Undercut and vertical-wall profiles are controlled by the same three levers in opposite directions: low image-wise dose + low reversal-bake temperature + longer development time maximizes undercut for lift-off, while high dose + high bake temperature + shorter development time produces vertical walls suited to etch masking. Critically, the image-wise exposure dose differs by process mode for the same grade — 38 mJ/cm² if used as a plain positive resist versus 42 mJ/cm² in the image-reversal negative mode — so the two figures must not be conflated; this recipe records the negative/image-reversal dose since that matches the resist's headline classification (tone: image-reversal), with the positive-mode figure noted separately. No h-line- or i-line-isolated dose is published anywhere; both the 42 mJ/cm² image-wise and 74 mJ/cm² flood-exposure doses are broadband (365/405/436 nm) figures.

07 / Sources

Sources & disclaimer

  • AllresistAR-U 4030 datasheet (As of January 2017) · accessed 2026-07-10
  • https://www.allresist.com/portfolio-item/developer-ar-300-47/ — Allresist's own product page for developer AR 300-47: gives its main component as TMAH and its metal-ion content as under 0.1 ppm. Read together with the AR 300-26 page (sodium borate / sodium hydroxide) and the AR 300-35 page (sodium metasilicate / phosphate), it establishes that the developers this resist's own "Development recommendations" table offers span both a metal-ion-free and a metal-ion-containing chemistry.

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.

Cite this recipe

NANYTE. "AR-U 4030 process recipe." NANYTE Photoresist Library. https://nanyte.com/photoresists/ar-u-4030. Accessed 2026-07-26.

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