Silicon wafer wettability and aging behaviors: Impact on gold thin-film morphology

Xiaoming Yang, Zhaowei Zhong, Elhadj Diallo, Zhihong Wang, Weisheng Yue

Research output: Contribution to journalArticlepeer-review

14 Scopus citations

Abstract

This paper reports on the wettability and aging behaviors of the silicon wafers that had been cleaned using a piranha (3:1 mixture of sulfuric acid (H2SO4, 96%) and hydrogen peroxide (H2O 2, 30%), 120 °C), SC1 (1:1:5 mixture of NH4OH, H 2O2 and H2O, at 80°C) or HF solution (6 parts of 40% NH4F and 1 part of 49% HF, at room temperature) solution, and treated with gaseous plasma. The silicon wafers cleaned using the piranha or SC1 solution were hydrophilic, and the water contact angles on the surfaces would increase along with aging time, until they reached the saturated points of around 70°. The contact angle increase rate of these wafers in a vacuum was much faster than that in the open air, because of loss of water, which was physically adsorbed on the wafer surfaces. The silicon wafers cleaned with the HF solution were hydrophobic. Their contact angle decreased in the atmosphere, while it increased in the vacuum up to 95°. Gold thin films deposited on the hydrophilic wafers were smoother than that deposited on the hydrophobic wafers, because the numerous oxygen groups formed on the hydrophilic surfaces would react with gold adatoms in the sputtering process to form a continuous thin film at the nucleation stage. The argon, nitrogen, oxygen gas plasma treatments could change the silicon wafer surfaces from hydrophobic to hydrophilic by creating a thin (around 2.5 nm) silicon dioxide film, which could be utilized to improve the roughness and adhesion of the gold thin film. © 2014 Elsevier Ltd. All rights reserved.
Original languageEnglish (US)
Pages (from-to)25-32
Number of pages8
JournalMaterials Science in Semiconductor Processing
Volume26
Issue number1
DOIs
StatePublished - Oct 2014

ASJC Scopus subject areas

  • Mechanics of Materials
  • Materials Science(all)
  • Mechanical Engineering
  • Condensed Matter Physics

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