Supercritical Fluid Technology for Semiconductor Fabrication: Deposition of Metals and Mesoporous Silicates from Carbon Dioxide

Professor James J. Watkins
Department of Chemical Engineering
University of Massachusetts

DATE: Thursday, March 13, 2003
TIME: 4:00 p.m.
PLACE: Engineering II, Room 3361

ABSTRACT

Supercritical fluids (SCFs) offer a unique technology platform for semiconductor devices. This talk will describe SCF-based processes for metal deposition and the formation mesoporous silicate films for fabrication of advanced Cu interconnect structures in integrated circuits. As device dimensions recede below 90 nm, the deposition of defect-free high purity Cu films within high aspect ratio features becomes a significant challenge. Recently we demonstrated these demands can be met using chemical fluid deposition (CFD), a new approach that involves the chemical reduction of organometallic compounds in supercritical carbon dioxide. Reduction of Cu(II) or Cu(I) precursors with H2 or alcohol yields remarkably pure films with resistivities as low as 2.0 microohm-cm, well within standards required by the International Technology Roadmap for Semiconductors. CFD can also be used for the deposition of other metals including Pt, Pd, Au, Ni and their alloys using appropriate precursors.

Reduced device dimensions will also place greater demands on dielectrics, requiring the development of robust, mesoporous films. Here we describe a new approach to mesoporous silicates that involves the infusion and selective condensation of metal oxide precursors within one phase domain of a highly ordered, preformed block copolymer template dilated with supercritical carbon dioxide. The template is then removed to produce the mesoporous oxide. To date we have replicated ordered spherical and cylindrical morphologies to yield silica, organosilicate and mixed silica/organosilicate mesostructures in films over 1 micron thick while maintaining all the structural details of the sacrificial copolymer template. One advantage of the process is the elimination of excess alcohol from the reaction media, which provides a pathway for rapid and high degrees of network condensation. Moreover, separation of the template formation and infusion steps is enabling. Ultimately, structure on both the local and device levels can be achieved in three dimensions wholly in the polymer template using established techniques prior to infusion of the inorganic phase.