Physics / mechanism
Photoresists are radiation-sensitive polymer films deposited on wafers; exposure to light (or electrons) triggers a chemical change—either chain scission (positive tone) or cross-linking (negative tone)—that makes exposed or unexposed regions selectively soluble in developer. EUV resists (13.5 nm) operate via chemically amplified resist (CAR) chemistry or newer metal-oxide resist (MOR) platforms (e.g., Inpria/JSR tin-oxide). Key parameters: sensitivity (mJ/cm²), resolution (sub-10 nm features), and line-edge roughness (LER, target <2 nm 3σ). CARs battle the RLS trilemma—resolution, LER, and sensitivity cannot all be optimized simultaneously. MORs absorb EUV photons ~10× more efficiently than polymer CARs, enabling lower dose and better resolution, but etch selectivity and outgassing remain open problems. High-NA EUV (0.55 NA, ASML EXE series) tightens specs further: resists need <1.5 nm LER at ≤20 mJ/cm² sensitivity.
Competitive landscape
The primary competitive axis is CAR vs. MOR vs. directed self-assembly (DSA) as a resolution-enhancement layer. DSA (block copolymers, e.g., Brewer Science, EMD) can pitch-multiply but requires guiding patterns. Dry-deposited resists (Applied Materials Centura Sculpta platform) bypass spin-coat uniformity limits. E-beam resists (PMMA, HSQ) offer sub-5 nm resolution but lack throughput for HVM.
Companies using
Connected ideas
Sources
Frontier (open questions)
- To be added.