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

Well-ordered amino-terminated self-assembled monolayers (SAMs) were reprodu cibly 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 ag gregated AHAPS molecules were excessively adsorbed on the deposited AHAPS-S AM films. they were removed by sonication in ethanol, toluene, NaOH, and HN O3 aqueous solutions, conducted in that order. The thickness of the AHAPS-S AM as estimated by ellipsometry was 1.3 +/-0.1 nm. The AHAPS-SAM surfaces o bserved by atomic force microscopy appeared very smooth with a root mean sq uare roughness of about 0.15 nm in a several micron square area. This resul ted in low hysteresis between the advancing and receding water-contact angl es, which were determined to be 62 +/-3 degrees and 57.2 degrees, respectiv ely. Micropatterning of the SAM was also demonstrated on the basis of photo lithography 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 Amer ican Vacuum Society.