Porous ultra-low-dielectric constant thin film fabrication system

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Fabrication of porous ultra-low-dielectric (p-ULK) materials has been one of the main focuses in high performance integrated circuit (IC) materials research in recent years. These novel materials are used to insulate copper interconnect lines to prevent electrical shorts and reduce the resistance-capacitance delay in the back-end-of-line structures. The fabrication of p-ULK thin films requires a unique set of hardware that is not commonly available in university laboratory. It requires a plasma-enhanced chemical vapor deposition (PECVD) chamber with the capability to delivery silicate based and organic template liquid precursors. Nanometer size voids in the p-ULK materials are produced by exposing as-deposited films with the organic template molecules to high energy (greater 1kW) ultraviolet radiation in vacuum and at high temperature. This process vaporizes the organic molecules and produces empty voids or pores smaller than 5 nm in diameter. With careful control of the deposition conditions, the optimal porosity of 40 % volume is achievable using this fabrication technique. Neither of these advanced processing systems, liquid sourced PECVD and high energy UV cure, is available on the University of Waterloo campus. The new capabilities described in this proposal will support research projects not only in the p-ULK area but also in development of other novel materials, such as very thin (400A or less) nitrogen or oxygen-doped silicon carbide thin films. These thin films can be used for copper and hydrogen diffusion barriers in the IC. The high energy UV curing techniques for silicon nitride thin films are also being investigated, for advancement of strained silicon transistor technology.