https://nanyte.com/photoresists/lor-1a · last updated 2026-09-28
- Manufacturer
- MicroChem (MCC) — now Kayaku Advanced Materials
- Tone
- Not photoimageable (underlayer)
- Chemistry
- Ancillary (not photoimageable)
- Thickness
- 0.1–0.2 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 — 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 1A | 1000 | 0.16 |
| 1500 | 0.12 | |
| 2000 | 0.10 | |
| 2500 | 0.10 | |
| 3000 | 0.09 | |
| 3500 | 0.08 | |
| 4000 | 0.08 |
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 blue filled-diamond trace legended LOR 1A on the 'Thickness vs. Spin Speed - LOR A Thin Series' chart, p.5, the lowest of the three traces. Seven plotted markers at 500 rpm intervals; no numeric table accompanies the chart.
- The whole grade lives between 810 and 1,580 Å, so the entire spin sweep buys under 80 nm of thickness and the curve is flat from about 2500 rpm onward.
- Spin speed is a trim here, not a control — pick the grade for the thickness you want and use speed to fine-tune.
- 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. Hotter and longer both slow the dissolution and tighten the undercut. The published undercut-versus-bake curves (Figures 5a and 5b) are measured on LOR 10B, a B-series grade an order of magnitude thicker than this one, so they show the shape of the relationship rather than numbers to transfer here.
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 1A 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 1A is the thin end of the whole LOR range — a PMGI-based sacrificial film spun under a conventional photoresist and never exposed itself. The datasheet wants the LOR/PMGI film thicker than the deposited metal film, typically by 33 %, so at 810 to 1,580 Å LOR 1A suits depositions up to roughly 60-120 nm. That makes this the grade for fine features and thin depositions, where a micron-scale underlayer would undercut straight through the pattern. The A series dissolves more slowly than B or C for the same prebake, which is the other half of why it suits fine work — the ledge opens gradually and the process window is wider. Nothing here is exposed, so there is no dose, no tone and no post-exposure bake to set; prebake temperature and develop time do all the work.
Grades in this family
Other grades in the LOR A series line differ mainly in coating thickness:
Troubleshooting
Common failure modes for LOR 1A, 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.
Metal deposited over LOR 1A won't break at the feature edge. Is the underlayer too thin for my film?
Probably, if the deposit is more than about 60–120 nm, depending on spin speed. The datasheet wants the LOR film thicker than the deposited metal, typically by 33 %. Read from the spin chart, LOR 1A coats about 0.16 µm at 1000 rpm and about 0.08 µm at 4000 rpm, which carries roughly 120 nm of metal at the slow end and about 60 nm at the fast end. The chart stops at 1000 rpm, so for a deposit over about 120 nm move to LOR 2A or 3A rather than spinning outside the charted range.
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; Thickness vs. Spin Speed, LOR A Thin Series chart, p.5
The undercut under LOR 1A is barely there after develop. What do I change first?
The prebake temperature. The datasheet ranks it the strongest influence on undercut rate, and its bake data show dissolution slowing as the bake gets hotter, so step the temperature down inside the recommended 160-210 °C hotplate window. Develop time comes next: the LOR A undercut-versus-develop bars keep growing from 2 to 3 min, though they were measured on a 0.3 µm film, thicker than any 1A coat. No bake or develop time is published for 1A itself, so run the matrix the datasheet asks for, prebake temperature against develop time.
SOURCE: Kayaku Advanced Materials, "LOR and PMGI Resists" technical…
Kayaku Advanced Materials, "LOR and PMGI Resists" technical data sheet, Rev. D (August 2023) — Soft-Bake/Prebake Process and Figures 5a-5b, p.3; Undercut vs. Develop Time chart and Figure 6, p.4
Can LOR 1A give me an undercut below 0.35 µm, or a film under 100 nm?
Not within its rating. The product selection guide hatches out both the <0.35 µm undercut geometry and the <100 nm thickness band for the LOR A series; the finest undercut it recommends for LOR A is 0.35-0.5 µm, and it rates A films from 0.1 µm up. The 1A curve drops below 100 nm at about 2500 rpm and bottoms out near 80 nm, so the fast half of its spin range sits outside that band. For ledges or films that small the guide points to the PMGI SF and SFS products.
SOURCE: Kayaku Advanced Materials, "LOR and PMGI Resists" technical…
Kayaku Advanced Materials, "LOR and PMGI Resists" technical data sheet, Rev. D (August 2023) — LOR/PMGI Product Selection Guide, p.7; LOR A Thin Series chart, p.5
Can I take the LOR 1A edge bead off with acetone or my usual EBR solvent?
No. The datasheet says acetone and conventional resist edge-bead removers are not recommended with LOR/PMGI. Use EBR PG, which is made for these films, clears both the edge bead and whiskers, and also serves for spin-bowl clean-up and for reworking wafers that have not been baked yet. Once the film is baked, the removal route the datasheet gives is Remover PG or another NMP- or DMSO-based remover.
SOURCE: Kayaku Advanced Materials, "LOR and PMGI Resists" technical…
Kayaku Advanced Materials, "LOR and PMGI Resists" technical data sheet, Rev. D (August 2023) — Edge Bead Removal, p.3; Lift-Off Process, p.4
Sources & disclaimer
- MicroChem (MCC) — now Kayaku Advanced Materials — LOR 1A 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.