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Reliable Monolayer‐Template Patterning of SnO 2 Thin Films from Aqueous Solution and Their Hydrogen‐Sensing Properties
Author(s) -
Shirahata N.,
Shin W.,
Murayama N.,
Hozumi A.,
Yokogawa Y.,
Kameyama T.,
Masuda Y.,
Koumoto K.
Publication year - 2004
Publication title -
advanced functional materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.069
H-Index - 322
eISSN - 1616-3028
pISSN - 1616-301X
DOI - 10.1002/adfm.200305060
Subject(s) - materials science , thin film , monolayer , aqueous solution , anhydrous , wafer , silanol , chemical engineering , solvent , lithography , nanotechnology , organic chemistry , optoelectronics , catalysis , chemistry , engineering
We demonstrate a novel lithographic technique utilizing a solvent to fabricate a chemically based semiconductor microdevice from an aqueous solution. According to this technique, SnO 2 thin film could be integrated onto predefined sites on a SiO 2 /Si wafer. A patterned octadecyltrimethoxysilane self‐assembled monolayer (ODS‐SAM) was prepared by vacuum ultraviolet (VUV) irradiation through a photomask to use as a template for the fabrication of a micropatterned SnO 2 thin film on the SiO 2 /Si surface. A Sn‐based thin film was then deposited onto the entire surface of the ODS template from an aqueous solution containing 0.03 mol L –1 of SnCl 2 ·2H 2 O at 60 °C for 16 h in an ambient atmosphere. The thin film deposited on the methyl‐terminated area of the template was then peeled using an ultrasonic rinse in anhydrous toluene for 30 min, while the film deposited on the silanol area remained intact and undamaged. Rinsing in hydrophilic solvents did not facilitate peeling of the thin film from the methyl‐terminated area. We succeeded by this process in obtaining a high‐resolution, micropatterned Sn‐based thin film on an ODS‐SAM template on Si. The as‐deposited film was composed of fine Sn‐based particles. The sensitivity of this SnO 2 thin film to H 2 gas increases linearly with improving crystallinity. The effectiveness of anhydrous toluene as a rinse in solution lithography is discussed from the viewpoint of the high hydrophobic affinity between the rinse solvent and the terminal groups in the monolayer template.