Mapping of Process-Related Coating Defects on Wafers.
Presently we use commercial optical interferometry to map the topography
of coatings. These data are being analyzed to help understand the effects
of solvent evaporation on striation formation as well as other defects.
Effect of Surfactant Species on Spin Uniformity and Coating
Formation Behavior. This is aimed at whether the surfactant modifies the
thinning behavior because of different surface tractions during the extensional
fluid flow required by the spinning wafer. It also effects bead formation
around the periphery. Pinholes creation and other processes are also influenced.
Influence of Solvent Selection and Solvent Mixtures on
Coating Flatness. Solvent evaporation occurs only at the top surface --
thus evaporation also influences capillary effects that are also constrained
to that top surface region. Performing extensive tests with solvent/solute
mixtures is underway, including azeotrope systems.
Incorporation of Chemically Sensitive Dye Probes into
Coating Solutions. Dye molecules are being tested to act as probes of differential
solvent removal during the air-flow driven evaporation stages of spin-coating.
Data acquisition speed and signal strength issues are being evaluated.
Other Defects: All kinds of coating non-uniformity are
interesting within the present research scope. Edge-bead is a known coating
issue. Also, non-Newtonian fluid flow can contribute to gradually varying
thickness as a function of radius.
Dunbar
P. Birnie, III Professor
Department of Materials Science and Engineering
Rutgers, The State University of New Jersey
607 Taylor Rd.
Piscataway, New Jersey, 08854-8065
Major revisions installed in December 2004
Based on earlier version from July 2000
Updated in February 2005.
Page started 1 May 1998
(c) 1998,1999,2000,2004,2005D. P. Birnie, III
