95-61049 Roberts Recent needs and developments in information technology have spurred efforts to fabricate ever smaller features on silicon wafers. To do this, many lithographic techniques are being explored for their ability to provide high resolution photoresist masks capable of producing such submicron features. Needs for chip features down to 0.18 microns are predicted by the year 2002, with need for smaller 0.125 micron features soon after. Over the last decade, Langmuir-Blogett (LB) films, a surfactant based process, has been recognized as a viable candidate masking technique. The LB process has demonstrated ultrathin, pin-hole free masks down to resolutions of 0.010 microns (i.e. 10 nm); however, the LB process is limited to using only those few surface active monomers capable of both substrate adsorption and polymerization. In contrast, an alternative surfactant based process, developed in Surfactant Associates' laboratory, allows ultrathin film formation by practically any organic monomer capable of serving as a photoresist polymer. The process relies on electrostatically adsorbed bilayer surfactant aggregates (admicelles) in an aqueous environment into which a resist monomer is solubilized and polymerized to form polymerized thin films physically adsorbed to the metal oxide surface. The thin film mask is removed from the surface by changing the net surface charge by a pH change or imposing an electrical potential on the surface. Thin films formed by using admicelles have already found industrial use for modifying surfaces ranging from metal oxides used in thermoset polymer composites to drug delivery systems. It is proposed that this technique offers a variety of choices in fabricating ultrathin masks. Such masks offer a range of etching sensitivity for the lithographer while at the same time eliminating the need for volatile organic solvents used in standard lithographic processes. This process is aqueous based, environmentally acceptable, offers versatility, and resolution s equal to--if not greater--than LB films. The development of the ultrathin masks proposed here may allow integrated circuit fabricators to manufacture integrated circuits with much finer detail than is possible by the industry today--thus allowing the United States semiconductor industry to maintain its world wide technological lead. The dominance of the United States in semiconductor technology and the military and economic implications of that status are significant not only because of employment aspects but also national security concerns.
