There is no single "best" photoresist — only a best fit for a given film thickness, downstream step and tone. This page is a decision guide, not a product recommendation: each section below narrows the field by one property and links straight to that slice of the recipe library, so you end up comparing a handful of real, datasheet-cited resists instead of guessing at one.
If a term below is unfamiliar, the photolithography glossary defines it. Once you've picked a resist, your first pattern on a maskless tool walks the coat-expose-develop flow end to end.
1 · Tone: positive, negative, or image reversal
Tone decides which part of the film survives development. A positive resist leaves the *unexposed* areas behind — the exposed regions dissolve away — so your mask (or, on a maskless tool, your layout) directly defines what stays. A negative resist does the opposite: the exposed regions cross-link and stay, and the unexposed resist washes away. Neither is a fallback for the other; the choice follows from what the rest of your process needs.
For a straightforward etch mask or a general first pattern, a positive resist is the well-trodden path — browse the library filtered to positive tone.
For lift-off, the resist needs an undercut sidewall so evaporated or sputtered metal breaks cleanly at the resist edge — that's what a negative resist, or a positive resist run through an image-reversal process, is built to do. See image-reversal resists for how the reversal bake achieves that profile, or browse the library filtered to image reversal.
For a straight negative-tone job — no reversal step, no lift-off undercut, just "exposed stays" — browse the library filtered to negative tone.
Sources: MicroChemicals — Selection Criteria for Photoresists
2 · How thick a film do you need
Film thickness sets what the resist can do downstream: a thin film resolves fine features but etches through quickly, while a thick film survives a long etch or plating step but can't resolve as tight a pitch. Decide roughly where your process sits before you compare specific resists — the exact thickness for a given spin speed is read off each resist's own spin curve, never guessed.
Thin imaging — sub-micron to a few microns, for fine-pitch etch masks or general prototyping — browse the library filtered under 1 µm or filtered to 1–5 µm.
General-purpose coats in the 5–20 µm range cover most lift-off and mid-range etch-mask work — browse the library filtered to 5–20 µm.
Thick structural films — tens to hundreds of microns, for MEMS structures, high-aspect-ratio features, electroplating moulds or microfluidic channels — browse the library filtered to 20–100 µm or, for the very thickest builds, filtered above 100 µm. This is where epoxy negative resists such as SU-8 do their work.
3 · What the resist has to survive downstream
The downstream step is often the sharpest filter of all, because it constrains sidewall profile and chemical resistance directly.
Etch mask — the resist just needs to survive a wet or dry etch with a clean, vertical sidewall. Browse the library filtered to etch mask.
Lift-off — the resist (or underlayer beneath it) needs an undercut profile so deposited metal separates cleanly at the edge. Browse the library filtered to lift-off, and see lift-off underlayers for the non-photoimageable underlayer resists (LOR, PMGI-type) that sit beneath an imaging resist purely to shape that undercut.
Electroplating mould — a thick film with steep, vertical sidewalls that holds its shape as a plating mould. Browse the library filtered to electroplating / molding.
A handful of other applications get their own filter too — MEMS structural, microfluidics, high aspect ratio, and grayscale / 3D for a resist meant to hold an analogue, sloped profile — relevant if you're using a maskless tool's grayscale exposure rather than a binary pattern.
Sources: MicroChemicals — Selection Criteria for Photoresists
4 · Chemistry family
Once tone, thickness and application have narrowed the field, chemistry family is usually what's left to decide — it shapes process sensitivity, bake requirements and how forgiving the resist is to work with.
DNQ–novolak resists are the conventional positive-tone workhorse: broadly documented, exposable on a mercury-line tool without a post-exposure bake, and a reasonable default for a general etch-mask job. Browse the library filtered to DNQ–novolak.
Chemically amplified resists (CARs) trade a mandatory post-exposure bake for higher sensitivity and tighter process control — a fit when dose budget or resolution matters more than process simplicity. See chemically amplified resists, or browse the library filtered to chemically amplified.
Epoxy resists such as SU-8 are negative-tone and solvent-developed, built for the thick, high-aspect-ratio structures Section 2 described rather than for a thin etch mask. See epoxy negative resists, or browse the library filtered to epoxy.
A few less common families — bisazide-novolak, photopolymer, acrylate and polyimide resists, plus ancillary (non-photoimageable) underlayers — cover specific datasheet-documented cases and are worth a look once the four families above have narrowed things down; each has its own filter on the full library.
Common questions
What's the practical difference between positive and negative photoresist?
In a positive resist, the exposed areas dissolve in the developer and the unexposed areas remain — your layout defines what's removed. In a negative resist, the exposed areas cross-link and stay, and the unexposed resist washes away. Lift-off usually wants the undercut sidewall a negative resist or an image-reversal process gives; a straightforward etch mask usually reaches for positive.
How do I pick the right film thickness?
Start from what the film has to survive: a thin, sub-5-µm film resolves fine features for an etch mask or general prototyping, while a thick, tens-to-hundreds-of-micron film suits MEMS structures, electroplating moulds or high-aspect-ratio features. Filter the recipe library by thickness bucket, then read the exact spin speed for your target off the chosen resist's own spin curve.
Which resist should I use for lift-off?
Lift-off needs an undercut sidewall so deposited metal separates cleanly at the resist edge, which is why it usually calls for a negative resist, an image-reversal process on a positive resist, or a dedicated non-photoimageable underlayer (LOR/PMGI-type) beneath an imaging resist. Filter the library to lift-off, or to image reversal, to see the datasheet-cited options.
Do I need a chemically amplified resist?
Only if your process benefits from its higher sensitivity and tighter dose control — it also requires a mandatory post-exposure bake that a conventional DNQ-novolak resist doesn't. For a first run or a general etch mask, a well-documented DNQ-novolak resist is the simpler starting point.
Pattern it at 365 and 405 nm
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- MicroChemicals GmbH. Selection Criteria for Photoresists (application note). https://www.microchemicals.com/dokumente/application_notes/photoresist_selection_criteria.pdf
General photolithography reference material, not a specification of any particular NANYTE BEAM configuration, and not a substitute for a resist’s own datasheet. 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 mentioned.