LOR 5A process recipe

Spin coating

LOR 5A is spin-coated to 0.5–1.0 µm. The curve below is redrawn from the manufacturer's published data — read your target thickness off the vertical axis and take the matching spin speed as a starting point.

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.

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. General guidance (p.3): 'The recommended bake temperature range is 150°C - 200°C, although some PMGI products may be baked to 250°C... Hot plates are the preferred tool for the pre-bake; however, LOR/PMGI resists are also compatible with convection oven processes... a matrix design varying pre-bake temperature and time is recommended for process fine-tuning.' Separately, the Technical Data chart footnote (p.5) that includes LOR 5A's own spin curve states those plotted films 'were soft-baked at 180 ºC for 3 min' (180 s) — this is the measurement condition for the chart, not a stated process recommendation specific to LOR 5A. No grade-specific bake-temperature-vs-undercut-rate curve is published for LOR 5A: Figures 5a/5b (undercut rate vs. bake temperature and vs. bake time) are explicitly labeled 'LOR 10B' only, and Figure 6's dissolution-rate comparison groups grades only at the family level (LOR_A / LOR_B / SF / SF Slow bars, no per-grade numbers) at a single condition (180°C).Show more

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.Show more

Not published for this resist: Dilution, Time, Method, Rinse — characterize on-tool.

SOURCE: 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

Stripper

Remover PG (MicroChem/Kayaku). Baseline two-tank process: 60°C for 30 minutes in the first tank, then a 60°C rinse in the second tank; ultrasonic agitation improves removal efficiency. Actual time depends on pre-bake conditions, step coverage, and resist profile. Removal rate is reported as a function of soft-bake temperature and remover-bath temperature (Figure 9, p.4), but that figure is labeled for the 'SF Series', not LOR 5A specifically. Source: "Lift-Off Process", p.4.Show more

Storage

"Store upright in original sealed containers in a dry area between 4 and 27°C (40-80°F). Keep away from sources of ignition, light, heat, oxidants, acids, and reducers. Do not use after the expiration date (1 year from date of manufacture)." Source: "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).Show more

Not published for this resist: Hard bake, Descum, Etch resistance — characterize on-tool.

Where it's used

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.

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

1. Chen. A lift-off process for high resolution patterns using PMMA/LOR resist stack. Microelectronic Engineering (2004). doi:10.1016/j.mee.2004.02.053
   Sub-100 nm lift-off geometry demonstrated with a PMMA/LOR resist bilayer.

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 2026-07-10.

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