Atomic layer defect-free etching for germanium using HBr neutral beam

Takuya Fujii, Daisuke Ohori, Shuichi Noda, Yosuke Tanimoto, Daisuke Sato, Hideyuki Kurihara, Wataru Mizubayashi, Kazuhiko Endo, Yi-Ming Li, Yao-Jen Lee, Takuya Ozaki, Seiji Samukawa*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

4 Scopus citations


The authors developed extremely selective etching for making an atomically flat, defect-free germanium fin (Ge Fin) structure. The etching uses a hydrogen bromide (HBr) neutral beam (NB), and they investigated the etching reaction differences between the HBr NB and a Cl-2 NB. No sidewall etching by HBr NB occurred at 90 degrees C, although that by Cl-2 NB occurred at more than 90 degrees C. This was due to the different boiling points of GeBr4 and GeCl4 as the reacted layer was formed by NB irradiation on the Ge surface. As a result, the Ge sidewall etching by Cl-2 NB occurred above 90 degrees C, whereas that by HBr NB did not occur at 90 degrees C. Additionally, nonvolatile bromide protected layers, such as GeBr4 and SiBrxOy, were deposited on the Ge sidewall and the SiO2 top surface in case of using HBr, respectively. Then, the authors succeeded in fabricating the atomically flat, defect-free Ge Fin structure with the extremely selective HBr NB etching. This result shows that HBr NB can more precisely achieve sub-10-nm scale atomic layer Ge etching for 3D Fin-type MOSFETs.

Original languageEnglish
Article number051001
Pages (from-to)1-7
Number of pages7
JournalJournal of Vacuum Science and Technology A
Issue number5
StatePublished - Sep 2019




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