https://nanyte.com/photoresists/lor-2a · last updated 2026-09-28
- Manufacturer
- MicroChem (MCC) — now Kayaku Advanced Materials
- Tone
- Not photoimageable (underlayer)
- Chemistry
- Ancillary (not photoimageable)
- Thickness
- 0.1–0.3 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 2A | 1000 | 0.27 |
| 1500 | 0.20 | |
| 2000 | 0.18 | |
| 2500 | 0.16 | |
| 3000 | 0.15 | |
| 3500 | 0.14 | |
| 4000 | 0.13 |
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 2A on the 'Thickness vs. Spin Speed - LOR A Thin Series' chart, p.5, the middle of the three traces. Seven plotted markers at 500 rpm intervals; no numeric table accompanies the chart.
- A shallow curve across the whole sweep — 2,650 Å at 1000 rpm to 1,280 Å at 4000 — so the grade spans barely a factor of two and speed is a fine trim rather than a coarse control.
- It tracks roughly midway between the 1A and 3A traces at every speed, which is the practical way to place it: if a target falls between those two grades' ranges, this is the grade rather than a spin-speed compromise on either.
- 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. The published undercut-versus-bake curves (Figures 5a and 5b) are measured on LOR 10B, a faster B-series grade several times thicker, 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 2A 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 2A is a PMGI-based sacrificial underlayer from the slow-dissolving A series, spun beneath a conventional photoresist and never exposed itself. Its job is purely geometric: the underlayer has to out-dissolve the imaging resist far enough that the metal landing on the substrate and the metal landing on top of the resist never join, and it has to do that without the ledge running so far under the pattern that fine features collapse. At 0.128-0.265 µm this grade is aimed at thin depositions — thin enough that LOR 1A cannot reliably break the film, thick enough that LOR 3A would be generous. The A series is the slower of the three dissolution families, which widens the process window at the cost of needing a cooler or longer develop to reach the same undercut. Nothing here is exposed, so there is no dose, no tone and no post-exposure bake; 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 2A, 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.
I see scum at the foot of the imaging resist over LOR 2A. Is the underlayer intermixing?
It can, with one kind of top resist. A properly baked LOR/PMGI film is virtually insoluble in typical photoresist solvents and does not intermix, but one of the selection guide's advice notes says intermixing can occur with ethyl-lactate-based resists at temperatures below 180 °C. If the imaging resist is ethyl-lactate based, bake 2A at 180 °C or above. Expect a slower undercut in return, since a hotter bake lowers the dissolution rate.
SOURCE: Kayaku Advanced Materials, "LOR and PMGI Resists" technical…
Kayaku Advanced Materials, "LOR and PMGI Resists" technical data sheet, Rev. D (August 2023) — Substrate Preparation, p.2; Soft-Bake/Prebake Process, p.3; Product Selection Guide Advice note 3, p.7
How thick a metal film can LOR 2A lift off cleanly?
About 200 nm at best. The datasheet wants the underlayer thicker than the deposit, typically by 33 %. LOR 2A reaches about 0.26 µm at 1000 rpm and about 0.15 µm at 3000 rpm, which works out to roughly 200 nm and 110 nm of metal. The whole curve spans only about a factor of two, so if the deposit sits near the top of that, move to a thicker grade rather than spinning 2A slower still.
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
Undercut under LOR 2A varies from centre to edge of the wafer. Where do I look?
At the prebake. Its job, per the datasheet, is to dry the film and fix its development and undercut rate, and temperature is the strongest influence on that rate, so a bake that is not uniform across the wafer leaves a ledge that is not uniform either. Hot plates are the datasheet's preferred tool. It also asks for a controlled room, 20-25 °C ±1 °C and 35-45 % RH ±2 %, and names develop mode and develop time as influences, so keep agitation the same from wafer to wafer.
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, p.3; Processing Environment, p.8
Do I need a descum or barrier layer between LOR 2A and the imaging resist?
No. The imaging resist can be coated and prebaked directly over the film with no barrier layer and no plasma descum, and LOR needs neither an exposure nor a post-exposure bake in the simple bi-layer process. Take the imaging resist's bake, dose and any PEB from its own maker; 2A just develops alongside it in the same developer.
SOURCE: Kayaku Advanced Materials, "LOR and PMGI Resists" technical…
Kayaku Advanced Materials, "LOR and PMGI Resists" technical data sheet, Rev. D (August 2023) — Application and Processing the Patterning Resist Layer, p.3; Post Exposure Bake (PEB) Process, p.4
Sources & disclaimer
- MicroChem (MCC) — now Kayaku Advanced Materials — LOR 2A 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.