AVS 49th International Symposium
    Organic Films and Devices Tuesday Sessions
       Session OF+SS+EL+SC-TuA

Paper OF+SS+EL+SC-TuA5
Formation of Chemically Patterned Surfaces using Gas-Phase Oxalyl Chloride

Tuesday, November 5, 2002, 3:20 pm, Room C-102

Session: Organic Molecular Films
Presenter: M.C. Asplund, Brigham Young University
Authors: M.C. Asplund, Brigham Young University
G. Husseini, Brigham Young University
M.R. Linford, Brigham Young University
E.T. Sevy, Brigham Young University
Correspondent: Click to Email
Optical lithography is a common technique for the formation of electronic devices on semiconductor substrates. Here we show an analogous technique that allows the introduction of a reactive functional group (-COCl) onto an alkylated Si substrate, or onto any substrate that contains C-H groups. The importance of the -COCl group stems from its high reactivity with amino and hydroxyl groups. Our new method consists of exposing a C-H containing surface to a gaseous mixture of N2 and oxalyl chloride ( (COCl)@sub 2@ ) and then illuminating with 355 nm light. The UV photons form free radicals from the oxalyl chloride that then react with the C-H containing surface. We have shown using wetting, XPS, elipsometry and FT-IR spectroscopies that we have been able to form acid chloride functional groups on surfaces. By using simple optical masks we have shown that this functionalization occurs only where the sample is exposed to light. The key step to understanding the reaction mechanism for the surface reaction is understanding the formation and subsequent reaction of the radicals formed from the oxalyl chloride. Previous liquid phase reaction studies of oxalyl chloride with adamantane led to the suggestion that at 266 Cl is the primary radical formed, while at 355 nm the primary radical is the COCl radical. We have looked at the formation of radicals as a function of wavelength to analyze dissociation mechanism, and product energy distributions as well as the effect of pressure on radical formation. The minimum feature size which can be made using this method is given by the diffusion length of the radical. Thus the quenching must be understood and optimized to have controlled patterning of surfaces.