{"database":"biostudies-literature","file_versions":[],"scores":null,"additional":{"omics_type":["Unknown"],"volume":["5(10)"],"submitter":["Hsiao SN"],"pubmed_abstract":["Hafnium(IV) oxide (HfO<sub>2</sub>)-based materials have attracted substantial interest owing to their outstanding performance in advanced ultrathin semiconductor devices. However, achieving atomic-level precision and smoothness in HfO<sub>2</sub> etching remains a major challenge, primarily due to the nonvolatility of reaction products formed with halogen-based chemicals at room temperature. Herein, a facile cyclic atomic-layer etching (ALE) process capable of etching HfO<sub>2</sub> films at room temperature without the use of halogen-based chemicals is reported. The ALE process consists of a surface nitrogenation step via N<sup>+</sup>-ion bombardment during N<sub>2</sub> plasma exposure, followed by O<sub>2</sub> plasma treatment to remove the surface-modified layer through the formation of volatile etching byproducts-most likely hafnium nitrates. This process enables precise, subatomic-level etching of HfO<sub>2</sub>, achieving an etch depth per cycle ranging from 0.23 to 1.07 Å/cycle, depending on the N<sup>+</sup> ion energy. Additionally, this cyclic ALE method effectively smooths the HfO<sub>2</sub> surface, yielding a 60% reduction in surface roughness after 20 cycles. Based on the proposed mechanism, this facile ALE process can be extended to other transition metal oxides and offers a sustainable route for fabricating advanced functional oxide-based devices, without generating corrosive or toxic wastes."],"journal":["Small science"],"pagination":["2500251"],"full_dataset_link":["https://www.ebi.ac.uk/biostudies/studies/S-EPMC12499433"],"repository":["biostudies-literature"],"pubmed_title":["Halogen-Free Anisotropic Atomic-Layer Etching of HfO&lt;sub&gt;2&lt;/sub&gt; at Room Temperature."],"pmcid":["PMC12499433"],"pubmed_authors":["Yiu PM","Hori M","Hsiao SN","Chang LC","Sekine M","Lee JW"],"additional_accession":[]},"is_claimable":false,"name":"Halogen-Free Anisotropic Atomic-Layer Etching of HfO&lt;sub&gt;2&lt;/sub&gt; at Room Temperature.","description":"Hafnium(IV) oxide (HfO<sub>2</sub>)-based materials have attracted substantial interest owing to their outstanding performance in advanced ultrathin semiconductor devices. However, achieving atomic-level precision and smoothness in HfO<sub>2</sub> etching remains a major challenge, primarily due to the nonvolatility of reaction products formed with halogen-based chemicals at room temperature. Herein, a facile cyclic atomic-layer etching (ALE) process capable of etching HfO<sub>2</sub> films at room temperature without the use of halogen-based chemicals is reported. The ALE process consists of a surface nitrogenation step via N<sup>+</sup>-ion bombardment during N<sub>2</sub> plasma exposure, followed by O<sub>2</sub> plasma treatment to remove the surface-modified layer through the formation of volatile etching byproducts-most likely hafnium nitrates. This process enables precise, subatomic-level etching of HfO<sub>2</sub>, achieving an etch depth per cycle ranging from 0.23 to 1.07 Å/cycle, depending on the N<sup>+</sup> ion energy. Additionally, this cyclic ALE method effectively smooths the HfO<sub>2</sub> surface, yielding a 60% reduction in surface roughness after 20 cycles. Based on the proposed mechanism, this facile ALE process can be extended to other transition metal oxides and offers a sustainable route for fabricating advanced functional oxide-based devices, without generating corrosive or toxic wastes.","dates":{"release":"2025-01-01T00:00:00Z","publication":"2025 Oct","modification":"2026-06-04T06:58:30.413Z","creation":"2026-05-06T03:12:54.442Z"},"accession":"S-EPMC12499433","cross_references":{"pubmed":["41058728"],"doi":["10.1002/smsc.202500251"]}}