Fig. 1. Compounds tested as photoacid generators for EUV lithography^[62]

Fig. 2. Pathways for photoacid generation and relative potential energy^[65]. (a) Pathway A; (b) pathway B; (c) pathway C; (d) relative potential energy

Fig. 3. Negative n-CAR photoresist and 20 nm lines^[66]

Fig. 4. Synthesized end-cap functionalized polyphthalaldehyde ^[67]

Fig. 5. Scanning electron microscope images of PSTS_0.7 patterns obtained after EUV exposure^[68]

Fig. 6. Structures of molecular photoresist containing different numbers of sulfonium triflate groups ^[69]

Fig. 7. Structures of SP-BOC, SP-AD and SP-BU^[70]

Fig. 8. Structure of TPSi-Boc_x molecular glass ^[71]

Fig. 9. Two major pathways are anticipated in EUV-induced cross-linking of HSQ cages^[77]. (a) Dehydrogenation reaction;

Fig. 10. Radical generation processes of TPSnSt through photodecomposition^[82]

Fig. 11. Synthesis of MAPDST-co-ADSM^[83]

Fig. 12. Mechanism for solubility switching reactions induced by electron beam irradiation^[88]. (a) Following interaction with energetic electrons (or EUV photon) ligand decomposition is initiated to produce Hf cation, a CO₂ molecule, and propenyl radical; (b) diffusion of propenyl radical to neighboring methacrylate ligand results in attachment via vinylic methylene group, resulting in larger radical ligand; (c) radical produced in Fig.12(b) can attach to neighboring cluster via its vinylic group, thereby linking adjacent clusters and propagating radical such that cluster can participate in further reaction; (d) in addition to pathway described in Figs.12(b) and (c), cross-linking can also occur in similar fashion via cation that is generated in Fig.12(a). Here, Hf cation reacts with vinylic group of neighboring cluster in fashion analogous to propenyl radical in Fig.12(b) to form cross-linked cation structure that can participate in further reaction

Fig. 13. Illustration of assembly of In₁₂-oxo clusters with chemical modification and patterning evaluation^[90]

Fig. 14. Radiation-induced intermolecular free radical polymerization and radical coupling between surface ligands of Zr₆O₄(OH)₄(C₄H₅O₂)₁₂^[38]

Fig. 15. Schematic illustration of thiol–ene reaction and click lithography^[93]. (a) Photoinitiated thiol–ene reaction; (b) representation of click lithography approach; (c) resist film composed of ZrO₂-MAA MOCs and thiol compounds; (d) crosslinked and non-crosslinked structures formed by radiation-induced thiol–ene click reaction

Fig. 16. Schematic of Zn-TBA crosslinked strategy^[94]

Fig. 17. R-4 under different EUV lithography resolutions^[96]. (a)‒(c) SEM images; (d)‒(f) AFM images

Fig. 18. Schematic of structure of MOCs, with coordination bonds between metals and ligands highlighted in ring