Center for Sustainable Materials Chemistry (CSMC) and Department of Chemistry, Oregon State University, Corvallis, OR, 97331-4003, USA.
Angew Chem Int Ed Engl. 2016 May 17;55(21):6221-4. doi: 10.1002/anie.201601134. Epub 2016 Apr 20.
Selective dissolution of hafnium-peroxo-sulfate films in aqueous tetramethylammonium hydroxide enables extreme UV lithographic patterning of sub-10 nm HfO2 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 [Hf6 (μ-O2 )6 (μ-OH)6 (OH)12 ]⋅38 H2 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.
在四甲基氢氧化铵水溶液中选择性溶解过氧硫酸铪薄膜，可实现小于 10nm 的 HfO2 结构的极紫外光刻图形化。然而，在这些碱性条件（pH＞10）下，铪的形态未知，因为对铪水化学的研究仅限于酸。在这里，我们报告了首例从碱中分离出的多核羟基金属铪簇合物的合成、晶体生长和结构表征，[TMA]6[Hf6(μ-O2)6(μ-OH)6(OH)12]·38H2O。通过小角 X 射线散射（SAXS）和电喷雾电离质谱（ESI-MS）详细研究了该簇合物的溶液行为，包括通过氢键的超分子组装。该研究为铪的水化学开辟了一个新的篇章，例证了两性簇合物的概念，并为个位数纳米光刻中的关键工艺提供了信息。
