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Amphoteric Aqueous Hafnium Cluster Chemistry
Author(s) -
GobernaFerrón Sara,
Park DeokHie,
Amador Jenn M.,
Keszler Douglas A.,
Nyman May
Publication year - 2016
Publication title -
angewandte chemie international edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.831
H-Index - 550
eISSN - 1521-3773
pISSN - 1433-7851
DOI - 10.1002/anie.201601134
Subject(s) - hafnium , tetramethylammonium hydroxide , aqueous solution , chemistry , electrospray ionization , inorganic chemistry , small angle x ray scattering , supramolecular chemistry , cluster (spacecraft) , mass spectrometry , zirconium , crystallography , crystal structure , scattering , organic chemistry , computer science , physics , optics , programming language , chromatography
Selective dissolution of hafnium‐peroxo‐sulfate films in aqueous tetramethylammonium hydroxide enables extreme UV lithographic patterning of sub‐10 nm HfO 2 structures. Hafnium speciation under these basic conditions (pH>10), however, is unknown, as studies of hafnium aqueous chemistry have been limited to acid. Here, we report synthesis, crystal growth, and structural characterization of the first polynuclear hydroxo hafnium cluster isolated from base, [TMA] 6 [Hf 6 (μ‐O 2 ) 6 (μ‐OH) 6 (OH) 12 ]⋅38 H 2 O. The solution behavior of the cluster, including supramolecular assembly via hydrogen bonding is detailed via small‐angle X‐ray scattering (SAXS) and electrospray ionization mass spectrometry (ESI‐MS). The study opens a new chapter in the aqueous chemistry of hafnium, exemplifying the concept of amphoteric clusters and informing a critical process in single‐digit‐nm lithography.