An investigation of the mechanical strengthening effect of hydrogen anneal for silicon torsion bar

Ryo Hajika, Shinya Yoshida, Yoshiaki Kanamori, Masayoshi Esashi, Shuji Tanaka

Research output: Contribution to journalArticle

8 Citations (Scopus)

Abstract

This paper reports on the use of hydrogen anneal to enhance the torsional fracture strength of dry-etched single crystal silicon (SCS) microstructures. Moving-magnet-type scanning mirrors with torsion bars were employed as fracture test specimens. Two types of device were fabricated using SCS and silicon-on-insulator (SOI) wafers by deep reactive ion etching (DRIE). For the SCS-wafer-based device, scalloping on DRIE sidewalls were smoothed out and the fracture strength of the torsion bar was improved by a factor of three by 120 min hydrogen anneal. For the SOI-wafer-based device, hydrogen anneal introduced surface irregularity onto the Si sidewalls by hydrogen-induced etching with the existence of SiO2. As a result, the fracture strength of the torsion bar was degraded contrarily. Therefore, hydrogen anneal is effective in improving the mechanical reliability of SCS microstructures without SiO2.

Original languageEnglish
Article number105014
JournalJournal of Micromechanics and Microengineering
Volume24
Issue number10
DOIs
Publication statusPublished - 2014 Oct 1

Keywords

  • MEMS
  • fracture strength
  • hydrogen anneal
  • scanning mirror
  • single crystal silicon

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Mechanics of Materials
  • Mechanical Engineering
  • Electrical and Electronic Engineering

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