https://nanyte.com/photoresists/lor-5a · last updated 2026-07-26
- Manufacturer
- MicroChem (MCC) — now Kayaku Advanced Materials
- Tone
- Not photoimageable (underlayer)
- Chemistry
- Ancillary (not photoimageable)
- Thickness
- 0.5–1.0 µm
- Exposure dose
- Not exposed — dissolves in developer
- Developer
- Document does not name a specific commercial developer product for LOR 5A; general text states LOR/PMGI is compatible with both metal-ion-free (MIF) and metal-ion-bearing (MIB) 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 5A | 1000 | 0.98 |
| 2000 | 0.67 | |
| 3000 | 0.55 | |
| 4000 | 0.47 |
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 "Spin Speed vs Thickness - Intermediate Films", p.5 of MicroChem "LOR and PMGI Resists" datasheet. This figure plots five grades: LOR 7B (blue square), LOR 5A (red circle), LOR 5B (green x), a COMBINED 'LOR 3A, LOR 3B' trace (black diamond), and SF6 (purple triangle). LOR 5A is the red-circle series specifically because it has its OWN distinct legend entry ('LOR 5A', not grouped with any other grade) and its own separate curve, clearly offset above the neighboring LOR 5B (green) and well above the combined LOR 3A/3B (black) trace in the same chart — it is its own trace, not the combined multi-grade series. Only 4 markers are plotted for LOR 5A (1000/2000/3000/4000 rpm); no 1500/2500/3500 rpm points exist for this series (unlike SF6, which has more points in the same figure). A figure read, ±10-15% plausible per-point error, not a numeric table. Chart footnote (p.5): 'Products were soft-baked at 180 ºC for 3 min' — the measurement condition for the plotted films, not a stated LOR-5A-specific process bake recommendation.
- Only 4 spin-speed points (1000/2000/3000/4000 rpm) are plotted for LOR 5A; extrapolation below 1000 or above 4000 rpm is not supported by the chart.
- The page's boxed 'RECOMMENDED COATING PARAMETERS' (dispense 5 ml on a 150 mm Si wafer, dynamic dispense 3-5 s at 300-500 rpm, acceleration 10,000 rpm/s, terminal spin speed 3,000 rpm, spin time 45 s, EBR PG for edge-bead removal) appears once for the whole Technical Data page (p.5) and is not stated to be grade-specific, so it is recorded here as general page-level guidance rather than a confirmed LOR-5A parameter.
- Separately, general text (p.2) states spin speeds of 2,500-4,500 rpm give 'maximum coating uniformity' across the LOR/PMGI line, with lower speeds favored for larger or irregular/topographic substrates.
- 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
- Not published — characterize on-tool
- Notes
- THE BAKE TEMPERATURE IS THE UNDERCUT CONTROL, and the document gives only ranges, not an LOR-5A-specific scalar.
SOURCE: p.3 ("Soft-bake/Prebake Process") and p.5 chart footnote, MicroChem "LOR and PMGI Resists" datasheet
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
- Document does not name a specific commercial developer product for LOR 5A; general text states LOR/PMGI is compatible with both metal-ion-free (MIF) and metal-ion-bearing (MIB) developer chemistries.
- Developer family
- TMAH or buffered alkaline
Not published for this resist: Dilution, Time, Method, Rinse — characterize on-tool.
SOURCE: p.1 ("Compatible with TMAH and metal-ion bearing developers")…
p.1 ("Compatible with TMAH and metal-ion bearing developers"), p.4 ("Development Process"), and p.6 Product Selection Guide (Developer Compatibility row), MicroChem "LOR and PMGI Resists" datasheet
Hard bake, etch & strip
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 develop-time and pre-bake-temperature-controlled dimension, not a lithographic one: the datasheet states pre-bake temperature has 'the greatest influence on undercut rate,' with pre-bake time, the imaging resist's own exposure dose, developer choice, develop mode, and develop time as secondary factors. 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 pre-bake temperature/time and develop time, not exposure.
Grades in this family
Other grades in the LOR A series line differ mainly in coating thickness:
| Grade | Thickness |
|---|---|
| LOR 3A | 0.3–0.6 µm |
| LOR 5A (this page) | 0.5–1.0 µm |
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.
Is LOR 5A a photoresist — is it exposed?
No. LOR 5A is a non-photoimageable PMGI-type underlayer — it is spin-coated beneath a conventional photoresist and is never itself exposed. It carries no dose, tone or pattern of its own; only the imaging resist above it is exposed and developed. The datasheet states LOR/PMGI does not require an exposure step in the standard bilayer lift-off process.
SOURCE: MicroChem 'LOR and PMGI Resists' datasheet Rev. A, p.4 (LOR/PMGI does not require an exposure step)
How do I control LOR 5A undercut for lift-off?
Undercut is governed chiefly by pre-bake (soft-bake) temperature — the datasheet states it has the greatest influence on undercut rate — with pre-bake time, the imaging resist's dose, developer choice, develop mode and develop time as secondary factors. Recommended bake range is 150–200 °C; a matrix varying pre-bake temperature and time is recommended for tuning. No grade-specific undercut-rate curve is published for LOR 5A (the only such curves are for LOR 10B), so its undercut rate should be characterized on-tool.
SOURCE: MicroChem 'LOR and PMGI Resists' datasheet Rev. A, Soft-bake/Prebake Process, p.3
Which developer should I use for LOR 5A?
The datasheet does not name a specific commercial developer for LOR 5A; it states only that LOR/PMGI is compatible with both metal-ion-free (MIF) and metal-ion-bearing developer chemistries. The Product Selection Guide gives compatibility at family level (LOR A → 0.26N MIF; LOR B → 0.24N MIF and MIB), but never states which family LOR 5A belongs to — so no developer, dilution or time is published for it specifically. Select and characterize on-tool.
SOURCE: MicroChem 'LOR and PMGI Resists' datasheet Rev. A, Development Process p.4 + Product Selection Guide p.6
What are the lift-off failure modes with LOR 5A and how are they tuned?
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 are tuned via pre-bake temperature/time and develop time — not exposure, since LOR 5A is never exposed.
SOURCE: MicroChem 'LOR and PMGI Resists' datasheet Rev. A (lift-off…
MicroChem 'LOR and PMGI Resists' datasheet Rev. A (lift-off failure modes; undercut set by pre-bake temperature/time and develop time)
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: MicroChem 'LOR and PMGI Resists' datasheet Rev. A, Substrate preparation, p.2
Sources & disclaimer
- MicroChem (MCC) — now Kayaku Advanced Materials — LOR 5A datasheet (Rev. A (printed at the bottom of p.7; no other date is printed anywhere in the document)) · accessed 2026-07-10
- "Substrate preparation", p.2.
- "Lift-Off Process", p.4.
- "LOR/PMGI Storage", p.7 (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 2026-07-26.