https://nanyte.com/photoresists/lor-15a · last updated 2026-09-28
- Manufacturer
- MicroChem (MCC) — now Kayaku Advanced Materials
- Tone
- Not photoimageable (underlayer)
- Chemistry
- Ancillary (not photoimageable)
- Thickness
- 1.0–2.6 µm
- Exposure dose
- Not exposed — dissolves in developer
- Developer
- 0.26N or 0.24N TMAH (no product named); metal-ion-bearing developers are not rated for LOR A (selection guide, p.7).
- Applications
- Lift-off
Cross-checked — the spin curve (where published) and the single-value figures were read twice, independently, from the datasheet, with any disagreement settled against it.
- Substrate
- Underlayer
- Resist
- Exposed
Spin coating
Data points
| Series | rpm | µm |
|---|---|---|
| LOR 15A | 1000 | 2.6 |
| 1500 | 1.9 | |
| 2000 | 1.6 | |
| 2500 | 1.3 | |
| 3000 | 1.1 | |
| 3500 | 1.0 | |
| 4000 | 0.99 |
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 — the purple cross-marker trace legended LOR 15A on the 'Thickness vs. Spin Speed - LOR A Thick Series' chart, p.5, the highest of the four traces. Seven plotted markers at 500 rpm intervals; no numeric table accompanies the chart.
- The steepest trace on the A-thick chart: 25,600 Å at 1000 rpm falls to 15,500 Å by 2000 and flattens toward 9,900 Å at 4000 rpm, where it has essentially bottomed out.
- The whole range above about 1.5 µm lives below 2000 rpm, so the thick end is where speed control matters and a slow-spin target is worth confirming on a test wafer.
- Coating parameters are published for the product line rather than per grade: 5 ml dispensed dynamically over 3-5 s onto a 150 mm wafer at 300-500 rpm, 10,000 rpm/s acceleration to a 3,000 rpm terminal speed, 45 s spin, with EBR PG for edge-bead and whisker removal.
- Adhesion
- HMDS not required — "Primers, such as HMDS, are typically not required" when LOR/PMGI is used as recommended; the datasheet describes excellent adhesion across semiconductor substrates. To dehydrate the surface first, bake at 200 °C for 5 min. LOR/PMGI is virtually insoluble in typical photoresist solvents, so a properly baked underlayer does not intermix with the imaging resist above it.
Soft bake
- Soft bake
- 160–210 °C · hotplate
- Notes
- The prebake dries the film and fixes its dissolution and undercut rate, and no grade-specific temperature or time is published. The recommended prebake range for the product line is 160-210 °C, hotplate preferred, and some PMGI products bake as high as 280 °C. Prebake temperature has the greatest influence on undercut rate, with prebake time, developer choice, develop mode and especially develop time behind it. At this thickness there is substantially more solvent to drive out than on the sub-micron A grades, so bake time deserves its own place in the tuning matrix; the published undercut-versus-bake curves (Figures 5a and 5b) are measured on LOR 10B, a thinner and faster grade.
SOURCE: Rev. D p.3: 'The recommended bake temperature range is 160°C –…
Rev. D p.3: 'The recommended bake temperature range is 160°C – 210°C'; 'Hot plates are the preferred tool for the prebake step.'
Exposure
LOR 15A is not photoimageable. It is not exposed at all — it is coated beneath an imaged top resist and undercut laterally during development. See the development step below.
Development
- Developer
- 0.26N or 0.24N TMAH (no product named); metal-ion-bearing developers are not rated for LOR A (selection guide, p.7).
- Developer family
- TMAH or buffered alkaline
Not published for this resist: Dilution, Time, Method, Rinse — characterize on-tool.
SOURCE: Product description, the LOR/PMGI process-flow section and the…
Product description, the LOR/PMGI process-flow section and the product selection guide, Kayaku "LOR and PMGI Resists" technical data sheet, Rev. D (August 2023)
Hard bake, etch & strip
- Stripper
- Remover PG. EBR PG removes edge beads and whiskers and is also an effective spin-bowl cleaner and a rework solvent for unbaked wafers.
- Storage
- Store upright in original sealed containers in a dry area between 10 and 24 °C (50-76 °F), away from ignition sources, light, heat, oxidants, acids and reducers. Do not use after the expiration date, 13 months from manufacture.
Not published for this resist: Hard bake, Descum, Etch resistance — characterize on-tool.
Where it's used
Practical notes from the datasheet
LOR 15A is the thick end of the slow-dissolving A series, a PMGI-based sacrificial film spun beneath a conventional photoresist and never exposed. It exists for a specific combination: a deposit heavy enough to need a couple of microns of sacrificial layer underneath, on a pattern fine enough that a fast-dissolving B or C grade would undercut past the feature while the imaging resist above was still developing. That trade — thickness without speed — is the whole reason the A series extends this far up. Prebake temperature remains the primary control over how far the ledge opens, with develop time close behind, and on a film this thick bake time matters more than it does on the thin grades. Nothing here is exposed, so there is no dose, no tone and no post-exposure bake to set.
Grades in this family
Other grades in the LOR A series line differ mainly in coating thickness:
Troubleshooting
Common failure modes for LOR 15A, 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.
Undercut on a 2 µm LOR 15A coat is hard to control. Is the grade rated for that thickness?
Only partly. The selection guide recommends the LOR A series for 0.1-1 µm films and gives it just some compatibility at 1-5 µm, where LOR B is recommended. LOR 15A spends nearly its whole curve above a micron: about 1.0 µm at 4000 rpm, 1.5 µm at 2000 rpm and 2.6 µm at 1000 rpm. For films past 2 µm the datasheet says straighter sidewalls come from spray development, and develop time is set by the LOR and imaging-resist thicknesses together.
SOURCE: Kayaku Advanced Materials, "LOR and PMGI Resists" technical…
Kayaku Advanced Materials, "LOR and PMGI Resists" technical data sheet, Rev. D (August 2023) — Development Process, p.4; Thickness vs. Spin Speed, LOR A Thick Series chart, p.5; Product Selection Guide (Thickness Range), p.7
Metal over LOR 15A tears at the edges instead of releasing. Is the film thick enough?
Check the ratio first. The datasheet wants the LOR film thicker than the deposit, typically by 33 %. A 15A coat of about 2.6 µm at 1000 rpm carries roughly 1.9 µm of metal; at 2000 rpm the film is about 1.5 µm, good for about 1.1 µm. If the deposit is inside that and it still tears, the ledge is probably too short: lower the prebake within 160-210 °C or develop longer.
SOURCE: Kayaku Advanced Materials, "LOR and PMGI Resists" technical…
Kayaku Advanced Materials, "LOR and PMGI Resists" technical data sheet, Rev. D (August 2023) — Coating Process, p.2; Soft-Bake/Prebake Process, p.3; LOR A Thick Series chart, p.5
Thin whiskers of LOR 15A are left at the wafer edge after coating. How do I get rid of them?
EBR PG removes both edge beads and whiskers on LOR/PMGI films and works on most coating tracks; acetone and conventional resist edge-bead removers are not recommended. The datasheet adds that whiskers are reduced with the LOR C resists, especially in thicker applications.
SOURCE: Kayaku Advanced Materials, "LOR and PMGI Resists" technical data sheet, Rev. D (August 2023) — Edge Bead Removal, p.3
Sources & disclaimer
- MicroChem (MCC) — now Kayaku Advanced Materials — LOR 15A datasheet (Rev. D, August 2023 (printed in the footer of every page)) · accessed 2026-09-10
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.