https://nanyte.com/photoresists/lor-7a · last updated 2026-09-12
- Manufacturer
- MicroChem (MCC) — now Kayaku Advanced Materials
- Tone
- Not photoimageable (underlayer)
- Chemistry
- Ancillary (not photoimageable)
- Thickness
- 0.4–1.1 µm
- Exposure dose
- Not exposed — dissolves in developer
- Developer
- No specific commercial developer product is named for this grade; the datasheet states LOR/PMGI is compatible with both metal-ion-free (TMAH) and metal-ion-bearing developer chemistries.
- Applications
- Lift-off
Cross-checked — two independent extractions agree on the spin curve and the single-value figures.
- Substrate
- Underlayer
- Resist
- Exposed
Spin coating
Data points
| Series | rpm | µm |
|---|---|---|
| LOR 7A | 1000 | 1.1 |
| 1500 | 0.71 | |
| 2000 | 0.66 | |
| 2500 | 0.56 | |
| 3000 | 0.50 | |
| 3500 | 0.46 | |
| 4000 | 0.44 |
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 red filled-square trace legended LOR 7A on the 'Thickness vs. Spin Speed - LOR A Thick Series' chart, p.5, second from the bottom of the four traces. Seven plotted markers at 500 rpm intervals; no numeric table accompanies the chart.
- The curve has a pronounced knee: 10,700 Å at 1000 rpm drops to about 7,100 Å by 1500 and then eases, reaching 4,400 Å at 4000 rpm.
- Almost half the available thickness range is spent in the first 500 rpm, so slow spins on this grade need tight speed control while anything above 2000 rpm is forgiving.
- It runs just above LOR 5A across the sweep and the two converge at the fast end.
- One published quirk is worth knowing before fitting anything to this curve: the 1500 rpm point sits slightly below a smooth fit through its neighbours, because the 1500-2000 rpm step is shallower than the 2000-2500 one.
- That is how the manufacturer plots it, so the trace is not perfectly monotonic in slope around the knee.
- 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.
Soft bake
- Soft bake
- Not published — characterize on-tool
- Notes
- The prebake dries the film and fixes its dissolution and undercut rate, and no grade-specific temperature or time is published.
SOURCE: "Soft-Bake/Prebake Process" section and Figures 5a-5b, Kayaku…
"Soft-Bake/Prebake Process" section and Figures 5a-5b, Kayaku "LOR and PMGI Resists" technical data sheet, Rev. D (August 2023)
Exposure
LOR 7A 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
- No specific commercial developer product is named for this grade; the datasheet states LOR/PMGI is compatible with both metal-ion-free (TMAH) and metal-ion-bearing developer chemistries.
- 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 4 and 27 °C (40-80 °F), away from ignition sources, light, heat, oxidants, acids and reducers. Do not use after the expiration date.
Not published for this resist: Hard bake, Descum, Etch resistance — characterize on-tool.
Where it's used
Practical notes from the datasheet
LOR 7A is a PMGI-based sacrificial underlayer from the slow-dissolving A series, spun beneath a conventional photoresist and never exposed. It occupies the gap between LOR 5A and LOR 10A, and in practice that is exactly how it gets chosen: a target around 0.6-0.8 µm sits in the middle of this grade's usable band where its neighbours would each be working at the end of theirs. The underlayer is picked against the deposited film rather than the feature — it must be thicker than the metal so the deposit breaks cleanly at the edge — and the A series is the slower of the three dissolution families, so the undercut opens gradually and the process window is wider than a B or C grade would give. Nothing here is exposed, so prebake temperature and develop time are the only real controls.
Grades in this family
Other grades in the LOR A series line differ mainly in coating thickness:
Sources & disclaimer
- MicroChem (MCC) — now Kayaku Advanced Materials — LOR 7A 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 2026-09-12.