AVS 57th International Symposium & Exhibition
    Surface Science Wednesday Sessions
       Session SS2-WeM

Paper SS2-WeM11
A Model for the Hydroaffinity OH(1x1)-Si(100) and SiO2 via Ion Beam Analysis (IBA), Tapping Mode Atomic Force Microsccopy (TMAFM) and Surface Energy Analysis from Contact Angle Analysis

Wednesday, October 20, 2010, 11:20 am, Room Santa Ana

Session: Electron, Photon and Ion Beam Induced Surface Modification
Presenter: Q.B. Xing, Arizona State University
Authors: Q.B. Xing, Arizona State University
N. Herbots, Arizona State University
M.A. Hart, Arizona State University
R.J. Culbertson, Arizona State University
J.D. Bradley, Arizona State University
Correspondent: Click to Email
The hydroaffinity of Si-based surfaces is investigated as a function of surface defect density, topography and electrical carrier concentration via either doping and/or point defect concentration. Surface energy and the resulting hydrophobic or hydrophilic behavior of two surfaces of application for wafer bonding, OH(1x1)-Si(100) and beta-crystobalite SiO2. A series samples are implanted with increasing doses, annealed to obtain a uniform dopant depth profile in the first 10 nm. Their electrical activation is measured via substitutional fraction detected by ion channeling and sheet resistance measurements.

A combination of ion channeling, 4.265 ± 0.035 MeV 12C(alpha, alpha;)12C , 3.05 ± 0.005 16O(alpha, alpha)16O MeV Nuclear Resonance and 2.8 MeV Hydrogen Recoil Detection are used for high resolution compositional depth profiling of the first 10 nm of the surface. Tapping Mode Atomic Force Microscopy (TMAFM) provides statistical analysis of the topography of these Si-based surfaces at a length scale ranging from a few nm to several µm. Extended atomic terraces with low edges and defects density on OH(1x1)Si(100) and crystalline silicates such as beta-cristobalite and alpha-quartz can render an insulating surface hydrophobic, while small scale roughness and surface defects makes it more hydrophilic. The water affinity and surface energy is measured using the Sessile Drop method and the Young-Dupré analysis as a function of topographical, compositional and micro-structural surface analysis using TMAFM, IBA combined with ion channeling and X-ray diffraction respectively. This correlation explains the behavior of water condensation at the liquid/air interface of intraocular implants during vitro-retinal surgery after cataract extraction and intraocular lens (IOL) implantation.

Polymer adsorption on surfaces alters their hydroaffinity, can control condensation on silicone IOL’s [1] and enable for hermetic bonding in silica-based sensors in medical electronic implants [2]

[1] US Patent pending: "Molecular films for controlling hydrophobic, hydrophilic, optical, condensation and geometric properties of silicone implants surfaces, including intraoccular lenses used in cataract surgeries." Inventor(s): N. Herbots, J. D. Bradley, M. Hart, D. A. Sell, S. Whaley, Q. Bradley (November 09, 2009)

[2] US Patent Pending: “Methods for Wafer Bonding, and for Nucleating Bonding Nanophases”. Inventor(s): N. Herbots, J. D. Bradley, M. Hart, D. A. Sell, S. Whaley, R. J. Culbertson (April 30, 2010)