Molecular-scale growth of silicon oxide on polymer substrate through vacuum ultraviolet light-assisted photooxidation of organosilane precursor

• Published in: Thin solid films Vol. 437; no. 1; pp. 89 - 94
• Main Authors: Hozumi, Atsushi, Inagai, Hironobu, Yokogawa, Yoshiyuki, Kameyama, Tetsuya
• Format: Journal Article
• Language: English
• Published: Lausanne Elsevier B.V 01.08.2003; Elsevier Science
• Subjects: Adsorbed layers and thin films; Chemical vapor deposition; Chemical vapor deposition (including plasma-enhanced cvd, mocvd, etc.); Condensed matter: electronic structure, electrical, magnetic, and optical properties; Cross-disciplinary physics: materials science; rheology; Electron and ion emission by liquids and solids; impact phenomena; Exact sciences and technology; Materials science; Methods of deposition of films and coatings; film growth and epitaxy; Photoemission and photoelectron spectra; Physics; Polystyrene; Silicon oxide; Vacuum ultraviolet light; Silicon oxide; Vacuum ultraviolet light; Polystyrene; Chemical vapor deposition; Silanes; Atomic force microscopy; Inorganic compounds; Semiconductor materials; Roughness; Binary compounds; Crystal growth from vapors; Experimental study; Precursor; Thin films; CVD; Thickness; Transmission electron microscopy; Silicon oxides; Extreme ultraviolet radiation; Photooxidation; Vacuum deposition; X-ray photoelectron spectra
• ISSN: 0040-6090; 1879-2731
• DOI: 10.1016/S0040-6090(03)00662-X

Molecular-scale growth of silicon oxide was successfully demonstrated onto a polystyrene (PS) substrate at a relatively low temperature less than the glass transition temperature of PS. Our method consists of three processes. A hydrophobic PS substrate was first photochemically modified using vacuum ultraviolet light (VUV) of 172 nm wavelength from an excimer lamp. Organosilane was then chemisorbed from a precursor vapor of 1,3,5,7-tetramethylcyclotetrasiloxane (TMCTS) onto the VUV-modified PS substrate. Finally, each of our samples was again photoirradiated with the same excimer lamp. Using X-ray photoelectron spectroscopy, we confirmed that the chemisorbed TMCTS was photooxidized and converted to silicon oxide after only 3 min of VUV irradiation. Under atomic force microscopy the resulting oxide surface appeared smooth with its thickness estimated to be less than 1 nm by transmission electron microscopy. Due to the growth of this oxide layer of molecular-scale thickness, the charge density and surface acidity on the PS substrate drastically changed, becoming almost identical to those of native oxide on a Si substrate.