Enhanced Solubility of Zirconium Oxo Clusters from Diacetoxyzirconium(IV) Oxide Aqueous Solution as Inorganic Extreme‐Ultraviolet Photoresists

Abstract

Metal oxo clusters have drawn a great deal of attention as the extreme‐ultraviolet (EUV) photoresists. However, industrial implementation in the next‐generation lithography demands further improvements in their sensitivity and resolution. In this study, a zirconium oxo cluster with methacrylate and acetate ligands was synthesized from diacetoxyzirconium(IV) oxide aqueous solution for use as EUV photoresist materials. The obtained Zr oxo cluster, consisting of a Zr core and methacrylate and acetate ligands, was similar in size to Zr6O4(OH)4(methacrylate)12 cluster, but much more soluble in a variety of organic solvents. Open‐frame exposure tests revealed that the Zr oxo cluster served as a negative tone photoresist with a sensitivity greater than that of Zr6O4(OH)4(methacrylate)12 cluster. At a dose of 22 mJ/cm2 in the absence of photoacid generators, the Zr oxo cluster film resolved a pattern 15 nm in width, which is sufficiently low to meet the current technological requirements.

Fatty acid capped, metal oxo clusters as the smallest conceivable nanocrystal prototypes

“…16,17 Zirconium and hafnium oxo clusters are used as catalysts to make or break amide bonds, 18,19 and they are suitable as inorganic extreme-ultraviolet photoresists. 20,21 Subtle differences in cluster chemistry between Zr and Hf are exploited in the industrial separation of Zr from Hf. 22 Titanium oxo clusters exhibit exciting photo-redox properties.…”

Soft X-ray absorption and fragmentation of tin-oxo cage photoresists

“…1) are candidates for a new generation of extreme ultraviolet (EUV) photoresists: light-sensitive materials that change their solubility upon exposure to EUV light (13.5 nm, 92 eV). [1][2][3][4][5][6][7][8][9][10][11][12][13] Tin atoms strongly absorb EUV radiation, 14,15 which allows for photoresist layers to be thin (B20 nm) and still absorb a suitable fraction of the expensive EUV photons. Patterns with small critical dimensions can then be written on the photoresist while keeping the aspect ratio (ratio between height and width of a feature) small enough to avoid pattern collapse.…”

Novel hexameric tin carboxylate clusters as efficient negative-tone EUV photoresists: high resolution with well-defined patterns under low energy doses

“…Inorganic complexes are promising photoresist materials in EUV (extreme ultraviolet) lithography. [1][2][3][4] One obvious advantage is that the EUV absorption efficiencies of metal complexes such as Hf, [5][6][7][8][9][10][11][12] Zr, [13][14][15][16][17][18] Zn, 10,19,20 and Sn [21][22][23][24][25] are 2-3 folds as large as those of polymer-based photoresists. Despite intensive studies, very few inorganic photoresists 3,19 can reach high resolution EUV patterns with half pitches (HPs) <20 nm under low dosage <50 mJ cm −2 .…”