Highly hydroxylated hafnium clusters are accessible to high resolution EUV photoresists under small energy doses

Abstract

This work reports the success in accessing high-resolution negative-tone EUV photoresists without radical chain growth in the aggregation mechanism.

Synthesis of pentameric chlorotin carboxylate clusters for high resolution EUV photoresists under small doses

“…The Sn–Cl, Sn–vinyl and Sn–O 2 CBu t cleavages follow the reported mechanisms of tin carboxylate clusters. 14–16 Although the photolytic decomposition of Sn–O 2 CBu t and vinyltin groups also takes place for the blend ( 3 ), their rates are slow because a large proportion still remains at J = 60 mJ cm −2 as shown in Table 3. For the vinyltin groups, radical propagation at this functionality is not supportive.…”

“…Existing reports on metal clusters or nanoparticles predominantly feature oxide or carboxylate ligands owing to their ready availability. 6–25 However, oxide ligands exhibit photochemical inertness toward UV light in addition to their weak EUV absorptions. Although carboxylate ligands can be easily decomposed by EUV light, their sizes are somehow too large to facilitate the molecular aggregation of negative-tone photoresists.…”

“…Although carboxylate ligands can be easily decomposed by EUV light, their sizes are somehow too large to facilitate the molecular aggregation of negative-tone photoresists. 14,15 We have recently prepared a partially decarboxylated hafnium cluster Hf 6 O 4 (OH) 6 (C 4 H 9 CO 2 ) 10 that can achieve a HP = 16 nm pattern under high EUV doses 170–180 mJ cm −2 . 15 But another cluster such as Hf 6 (OH) 8 (C 4 H 9 CO 2 ) 8 containing less carboxylated ligands is more photosensitive to achieve a HP = 16 nm pattern with small 30–60 mJ cm −2 doses.…”

Multinuclear Tin-Based Macrocyclic Organometallic Resist for EUV Photolithography

“…(iii) During the postexposure baking (PEB) step before the developing process, acid diffusion mechanisms are accelerated and cause bridging or pinching failure patterns, thereby increasing LER. 18 of organic matters exhibit poor etching resistance, thereby making it difficult to produce low-aspect-ratio nanopatterns. 13,15,17,19−22 To overcome the problems arising from the intrinsic properties of the conventional photoresist materials, metal atoms such as Sn, Hf, Bi, Zn, In, Zr, Cu, and Cr, which exhibit high absorption coefficients over EUV, have been recently incorporated into organic ligands to afford efficient photoresists of small-molecule coordination complexes 25−33 or nanoclusters.…”

“…However, CAR photoresists have limitations in achieving nanopatterning with EUV lithography. − Among others, (i) due to the large diameter of free gyration of polymer (around 2–10 nm) − and (ii) acid diffusion, sub-20 nm patterning with sharp contrast is difficult to achieve. (iii) During the postexposure baking (PEB) step before the developing process, acid diffusion mechanisms are accelerated and cause bridging or pinching failure patterns, thereby increasing LER . (iv) Traditional CAR-type polymer photoresists that are composed of organic matters exhibit poor etching resistance, thereby making it difficult to produce low-aspect-ratio nanopatterns. ,,,− …”