@article{oai:nagoya.repo.nii.ac.jp:00012007, author = {Pal, Prem and Sato, Kazuo and Gosalvez, Miguel A and Kimura, Yasuo and Ishibashi, Ken-Ichi and Niwano, Michio and Hida, Hirotaka and Tang, Bin and Itoh, Shintaro}, issue = {6}, journal = {Journal of Microelectromechanical Systems, IEEE}, month = {Dec}, note = {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 silicon-surfactant 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.}, pages = {1345--1356}, title = {Surfactant Adsorption on Single-Crystal Silicon Surfaces in TMAH Solution: Orientation-Dependent Adsorption Detected by In Situ Infrared Spectroscopy}, volume = {18}, year = {2009} }