Abstract

It has been demonstrated in recent studies that laser-induced photochemical modifications of surface properties can be used in combination with nonlinear kinetics and interfacial chemistry for maskless patterning of thin films by selected-area growth.^1-3 With one exception,³ these new techniques have relied on photochemical lowering of surface-tension barriers to physical condensation, e.g., prenucleation; laser-modification of chemical surface properties will have practical advantages over the use of physical barriers, particularly on surfaces with previously defined structures and crystalline defects.¹ In this paper we describe a study in which chemical catalysts have been prepared by local photochemical reaction under UV-laser irradiation. Thin (monolayer) films of these laser-deposited surface agents are shown to predispose surfaces to "spontaneous" polymerization of ethylene or acetylene on exposure to these monomer vapors. The UV-laser deposition reaction for preparation of these catalysts involves a greater-than-unity-order reaction in a mixed-component adsorbed layer of TiCl₄ and Al₂(CH₃)₆. The method is far more efficient than direct radiation-driven polymerization, and is of particular interest as a method for the patterning of easily oxidized polymers, many of which are difficult or impossible to pattern by lithographic methods.

© 1985 Optical Society of America