A New Method of Preparing Monolayers on Silicon and Patterning Silicon Surfaces by Scribing in the Presence of Reactive Species

Abstract

Here we describe a new and simple method for preparing alkyl monolayers on silicon, which consists of mechanically scribing oxide-coated silicon while it is wet with 1-alkenes or 1-alkynes (neat or in inert solvents) under ambient conditions. X-ray photoelectron spectroscopy, time-of-flight secondary ion mass spectrometry, wetting data, and stability tests suggest covalent bonding of unsaturated species to exposed silicon surfaces. Enclosures (hydrophobic corrals) made by scribing silicon that is wet with unsaturated hydrophobic species hold droplets of water and liquids with substantially lower surface tensions. Wetting tests suggest that 1-alkynes make better hydrophobic corrals than 1-alkenes, and theoretical results suggest it should be more difficult for alkyl chains of chemisorbed 1-alkenes to pack than those of 1-alkynes. Underivatized interior regions of hydrophobic corrals are functionalized with polyelectrolyte multilayers. Theoretical energies for water and methanol droplets (gravitational and surface) in hydrophobic corrals are calculated, and a model of failure of liquid droplets in hydrophobic corrals is presented.

Wet chemical routes to the assembly of organic monolayers on silicon surfaces via the formation of Si–C bonds: surface preparation, passivation and functionalization

“…Those are: (a) the expanding literature on porous silicon chemistry and porous silicon biosensing applications; [54][55][56][57][58][59][60][61][62] (b) metal-insulator-semiconductor (MIS) studies on organic modified silicon surfaces; 39,43,48,[63][64][65][66][67] (c) chemomechanical functionalisation approaches (i.e. 'wetting and scribe' methods); 68,69 and (d) ultra-high vacuum reactions (UHV, 10 À10 mbar or lower) of unsaturated molecules on reconstructed semiconductor surfaces. 42,70,71 2.…”

Silicon and Silicon-Related Surfaces for Biosensor Applications

“…In addition, micro-contact printing (μCP) -a fast and simple patterning technique, which is frequently used for alkylthiols on gold and alkylsilanes on oxide surfaces [Xia & Whitesides, 1998] -is currently not feasible with 1-alkenes and 1-alkynes directly on H-Si, due to the extended reaction times required for monolayer formation and related difficulties to remain a oxide-free monolayer-silicon interface. Only recently a number of elegant soft lithographic [Jun, et al, 2002& Mizuno & Buriak, 2008& Perring, et al, 2007 and scanning probe [Niederhauser, et al, 2001& Niederhauser, et al, 2002& Yang, L., et al, 2005& Yang, M., et al, 2009] methods for patterning of organic monolayer on oxide-free silicon were published.…”

Theoretical modelling of surface phonons

“…Another hydrocarbon that has been found useful [27,28] for its adsorption on the Si(001) surface is methanol (CH 3 OH). Adsorption of this molecule could well be a precursor for low pressure chemical vapour deposition of SiO 2 .…”