Surfactant adsorption on single-crystal silicon surfaces in tmah solution: Orientation-dependent adsorption detected by in situ infrared spectroscopy

Prem Pal, Kazuo Sato, Miguel A. Gosalvez, Yasuo Kimura, Ken Ichi Ishibashi, Michio Niwano, Hirotaka Hida, Bin Tang, Shintaro Itoh

Research output: Contribution to journalArticlepeer-review

53 Citations (Scopus)

Abstract

This paper focuses on two aspects, macroscopic and microscopic, of pure and surfactant-added tetramethylammonium hydroxide (TMAH) wet etching. The macroscopic aspects deal with the technological/engineering applications of pure and surfactant-added TMAH for the fabrication of microelectromechanical systems (MEMS). The microscopic view is focused on the in situ observation of the silicon surface during etching in pure and surfactant-added TMAH solutions using Fourier transform infrared (FT-IR) spectroscopy in the multiple internal reflection geometry. The latter is primarily aimed at investigating the causes behind the change in the orientation-dependent etching behavior of TMAH solution when the surfactant is added. Silicon prisms having two different orientations ({110} and {100}) were prepared for comparison of the amount of adsorbed surfactant using FT-IR. Stronger and weaker adsorptions were observed on {110} and {100}, respectively. Moreover, ellipsometric spectroscopy (ES) measurements of surfactant adsorption depending on the crystallographic orientation are also performed in order to gain further information about the differences in the siliconsurfactant interface for Si{100} and Si{110}. In this paper, we determine the differences in surfactant adsorption characteristics for Si{110} and Si{100} using FT-IR and ES measurements for the first time, focusing both on the mechanism and on the technological/engineering applications in MEMS.

Original languageEnglish
Article number5289972
Pages (from-to)1345-1356
Number of pages12
JournalJournal of Microelectromechanical Systems
Volume18
Issue number6
DOIs
Publication statusPublished - 2009 Dec
Externally publishedYes

Keywords

  • Anisotropic etching
  • Ellipsometry
  • Fourier transform infrared (FT-IR) spectroscopy
  • IR
  • Microelectromechanical systems (MEMS)
  • Silicon
  • Surfactant
  • Tetramethylammonium hydroxide (TMAH)
  • Triton-X-100

ASJC Scopus subject areas

  • Mechanical Engineering
  • Electrical and Electronic Engineering

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