late notice

[Karen Barry <karen barry 2 bc edu>]

JOINT PHYSICS & CHEMISTRY COLLOQUIUM

Professor James J. Watkins


Department of Chemical Engineering and Co-Director, MassNanoTech
University of Massachusetts, Amherst

Supercritical fluids (SCFs) including carbon dioxide offer a unique 
technology platform for the fabrication of devices having feature 
dimensions in the sub-100 nm regime. This talk will describe SCF-based 
processes for metal deposition and the formation mesoporous silicate 
films for fabrication of devices with controlled architectures, 
including microelectronic devices, sensors, separation media and 
photonic materials. The preparation of Cu interconnect structures in 
advanced integrated circuits will be used as an illustrative example and 
other applications will be discussed.
As interconnect 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 technologically important metals 
including Pt, Pd, Au, Ni, Co and their alloys using appropriate 
precursors. For example, we recently deposited continuous Pd films deep 
within porous supports for membrane applications.
Reduced interconnect 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. Control over mesoporous oxide 
structures is enabling for a number of applications. For example 
oriented arrays of cylindrical nanopores would find application in 
catalysis, sensors and separations. The approach is extendable to other 
metal oxides, including titania for optical applications.


Wednesday, February 4, 2004
Higgins Hall, Room 310
4:00 p.m.

Refreshments
3:30
Higgins 230