Amino-terminated self-assembled monolayer on a SiO2 surface formed by chemical vapor deposition

Well-ordered amino-terminated self-assembled monolayers (SAMs) were reproducibly prepared on Si substrates covered with native oxide in a vapor of 12.5 vol% solution of N-(6-aminohexyl)-3-aminopropyltrimethoxysilane (H2N(CH2)(6)NHCH2CH2CH2Si(OCH3)(3),AHAPS) diluted with absolute toluene. Although aggregated AHAPS molecules were excessively adsorbed on the deposited AHAPS-SAM films. they were removed by sonication in ethanol, toluene, NaOH, and HNO3 aqueous solutions, conducted in that order. The thickness of the AHAPS-SAM as estimated by ellipsometry was 1.3 +/-0.1 nm. The AHAPS-SAM surfaces observed by atomic force microscopy appeared very smooth with a root mean square roughness of about 0.15 nm in a several micron square area. This resulted in low hysteresis between the advancing and receding water-contact angles, which were determined to be 62 +/-3 degrees and 57.2 degrees, respectively. Micropatterning of the SAM was also demonstrated on the basis of photolithography using an excimer lamp radiating vacuum ultraviolet light of 172 nm in wavelength. A microstructure composed of 5 mum x 25 mum rectangular features was successfully fabricated on an AHAPS-SAM surface. (C) 2001 American Vacuum Society.