https://nanyte.com/photoresists/lor-5a · last updated 2026-09-28
- Manufacturer
- MicroChem (MCC) — now Kayaku Advanced Materials
- Tone
- Not photoimageable (underlayer)
- Chemistry
- Ancillary (not photoimageable)
- Thickness
- 0.3–0.8 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 5A | 1000 | 0.82 |
| 1500 | 0.63 | |
| 2000 | 0.52 | |
| 2500 | 0.45 | |
| 3000 | 0.41 | |
| 3500 | 0.37 | |
| 4000 | 0.35 |
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 5A on the 'Thickness vs. Spin Speed - LOR A Thick Series' chart, p.5, the lowest of the four traces. Seven plotted markers at 500 rpm intervals; no numeric table accompanies the chart.
- The lowest trace on the A-thick chart, running 8,200 Å at 1000 rpm down to 3,500 Å at 4000 rpm.
- It sits directly beneath LOR 7A across the whole sweep and the two converge above 3000 rpm, so where a target falls in the overlap the slower spin on this grade is the more repeatable choice.
- 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 (hexamethyldisilazane) are typically NOT required to promote adhesion with PMGI/LOR products when used as recommended." LOR/PMGI is described as exhibiting 'excellent adhesion to most semiconductor, GaAs, and thin-film head substrates.' A dehydration bake (200°C, 5 min contact hot plate, or 30 min convection oven) is recommended before coating if maximum process reliability is needed.1
Soft bake
- Soft bake
- 160–210 °C · hotplate
- Notes
- The prebake is the undercut control, 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; the datasheet recommends a temperature/time matrix to tune a process rather than a single point. 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, so no grade-specific bake-versus-undercut data exists for LOR 5A.
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 5A 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, or another NMP- or DMSO-based remover. Baseline two-tank process: 60°C for 30 minutes in the first tank, then a 60°C rinse in the second tank; ultrasonic action improves removal efficiency. Removal rate depends on the LOR/PMGI soft-bake temperature and the remover bath temperature, and actual removal times vary with prebake conditions, subsequent processing and resist patterns. Source: "Lift-Off Process", p.4. Acetone and conventional edge-bead removers are not recommended with LOR/PMGI.2
- Storage
- "Store upright in original sealed containers in a dry area between 10-24 °C (50-76°F). Keep away from sources of ignition, light, heat, oxidants, acids and reducers. Do not use product after the expiration date (13 months from date of manufacture)."3
Not published for this resist: Hard bake, Descum, Etch resistance — characterize on-tool.
Where it's used
Practical notes from the datasheet
LOR 5A is an ancillary, non-photoimageable PMGI-type (polydimethylglutarimide) underlayer: it is spin-coated beneath a conventional photoresist and never exposed itself, so it carries no dose, tone, or lithographic pattern of its own — only the imaging resist above it is exposed and developed. The undercut geometry that enables clean metal lift-off is a bake- and develop-controlled dimension, not a lithographic one: the datasheet states prebake temperature has the greatest influence on undercut rate, with prebake time, choice of developer, develop mode, and particularly develop time also influential. No grade-specific bake-temperature-vs-dissolution-rate curve is published for LOR 5A — the only such curves in this document (Figures 5a/5b) are for LOR 10B — so LOR 5A's own undercut rate cannot be read off this datasheet and should be characterized on-tool. In practice, too little undercut leaves an insufficient re-entrant profile, so evaporated or sputtered metal bridges over the sidewall and lift-off fails or leaves ragged edges; too much undercut can collapse the unsupported span of imaging resist over the gap, degrading pattern fidelity — both failure modes are tuned via prebake temperature/time and develop time.
Grades in this family
Other grades in the LOR A series line differ mainly in coating thickness:
Troubleshooting
Common failure modes for LOR 5A, 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.
Does LOR 5A get exposed like a photoresist?
No. It is a lift-off underlayer, not an imaging layer: in the standard bilayer process LOR 5A needs no exposure of its own, and only the imaging resist above it is exposed and developed. The datasheet states LOR/PMGI do not require an exposure step in that process.
SOURCE: Kayaku Advanced Materials, "LOR and PMGI Resists" technical…
Kayaku Advanced Materials, "LOR and PMGI Resists" technical data sheet, Rev. D (August 2023) — Figure 4 process flow, p.2; Application and Processing the Patterning Resist Layer, p.3
How do I control LOR 5A undercut for lift-off?
With the prebake. The datasheet names prebake temperature as the strongest influence on undercut rate, with prebake time, developer choice, develop mode and particularly develop time also influential. Its recommended hotplate range is 160-210 °C, and for fine-tuning it asks for a matrix of prebake temperature against develop time. The only bake-versus-undercut curves it publishes are for LOR 10B, a thicker B-series grade, so measure the 5A rate on your own tool.
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
Which developer should I use for LOR 5A?
No developer product is named for LOR 5A. The datasheet says LOR/PMGI is optimized for metal-ion-free and metal-ion-bearing developers, and 5A is charted in the LOR A Thick Series; the selection guide recommends LOR A with both 0.26N and 0.24N TMAH and does not rate it with metal-ion-bearing developers. No dilution or develop time is published, because the LOR and imaging-resist thicknesses together set the time, so set it on-tool.
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 (Developer Compatibility), p.7
Metal over LOR 5A tears or stays joined at the edges after lift-off. What do I check?
Thickness against the deposit first. The datasheet wants the LOR film thicker than the metal, typically by 33 %, and relies on the re-entrant profile to break the deposited film. LOR 5A coats about 0.8 µm at 1000 rpm and about 0.35 µm at 4000 rpm, so it carries about 0.6 µm of metal at the slow end and 0.26 µm at the fast end. Then the undercut: a cooler prebake or a longer develop widens it, and the LOR A bars on the undercut-versus-develop chart grow from 2 to 3 min, though they were measured on a 0.3 µm film.
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 and Figure 4, p.2; Soft-Bake/Prebake Process and Figure 5a, p.3; Undercut vs. Develop Time chart, p.4; LOR A Thick Series chart, p.5
Does LOR 5A need HMDS priming?
No. Primers such as HMDS are typically not required to promote adhesion with PMGI/LOR products when used as recommended; LOR/PMGI has excellent adhesion to most semiconductor, GaAs and thin-film-head substrates. If maximum process reliability is needed, a dehydration bake (200 °C, 5 min on a contact hotplate or 30 min in a convection oven) is recommended before coating.
SOURCE: Kayaku Advanced Materials, "LOR and PMGI Resists" technical data sheet, Rev. D (August 2023), Substrate preparation, p.2
Sources & disclaimer
- MicroChem (MCC) — now Kayaku Advanced Materials — LOR 5A datasheet (Rev. D, August 2023 (printed in the footer of every page)) · accessed 2026-09-10
- "Substrate preparation", p.2.
- "Edge Bead Removal", p.3.
- "Storage", p.8 (general to all LOR/PMGI products; not stated to be LOR-5A-specific, but no grade-specific storage guidance exists in the document).
- Chen et al.. A lift-off process for high resolution patterns using PMMA/LOR resist stack. Microelectronic Engineering (2004). doi:10.1016/j.mee.2004.02.053Demonstrates sub-100 nm lift-off patterns using a PMMA/LOR bilayer resist stack, exploiting the controlled LOR undercut.
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.