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, Yiming Li, Yao Jen Lee, Takuya Ozaki, Seiji Samukawa

Research output: Contribution to journalArticlepeer-review

3 Citations (Scopus)


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 Cl2 NB. No sidewall etching by HBr NB occurred at 90 °C, although that by Cl2 NB occurred at more than 90 °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 Cl2 NB occurred above 90 °C, whereas that by HBr NB did not occur at 90 °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
JournalJournal of Vacuum Science and Technology A: Vacuum, Surfaces and Films
Issue number5
Publication statusPublished - 2019 Sep 1

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Surfaces and Interfaces
  • Surfaces, Coatings and Films


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