School of Chemical, Biological, and Environmental Engineering, Oregon State University , Corvallis, Oregon 97331-2072, United States.
ACS Appl Mater Interfaces. 2014 Feb 26;6(4):2917-21. doi: 10.1021/am405463u. Epub 2014 Feb 17.
High-resolution transmission electron microscopy (TEM) imaging and energy-dispersive X-ray spectroscopy (EDS) chemical mapping have been used to examine key processing steps that enable sub-20-nm lithographic patterning of the material Hf(OH)4-2x-2y(O2)x(SO4)y·qH2O (HafSOx). Results reveal that blanket films are smooth and chemically homogeneous. Upon exposure with an electron beam, the films become insoluble in aqueous tetramethylammonium hydroxide [TMAH(aq)]. The mobility of sulfate in the exposed films, however, remains high, because it is readily exchanged with hydroxide from the TMAH(aq) solution. Annealing the films after soaking in TMAH(aq) results in the formation of a dense hafnium hydroxide oxide material that can be converted to crystalline HfO2 with a high electron-beam dose. A series of 9 nm lines is written with variable spacing to investigate the cross-sectional shape of the patterned lines and the residual material found between them.
高分辨率透射电子显微镜（TEM）成像和能量色散 X 射线能谱（EDS）化学映射已被用于检查关键的处理步骤，这些步骤使得材料 Hf(OH)4-2x-2y(O2)x(SO4)y·qH2O（HafSOx）能够实现 20nm 以下的光刻图案化。结果表明，覆盖层薄膜是光滑且化学均匀的。在电子束照射下，薄膜在水溶液四甲基氢氧化铵（TMAH(aq)）中变得不溶。然而，暴露于薄膜中的硫酸盐的迁移率仍然很高，因为它很容易与 TMAH(aq)溶液中的氢氧根离子交换。在 TMAH(aq)浸泡后对薄膜进行退火，会形成致密的氧化铪氢氧化物材料，该材料可用高电子束剂量转化为结晶 HfO2。一系列 9nm 线以不同的间距写入，以研究图案化线的横截面形状和它们之间发现的残留材料。
