| Abstract |
A new method for determining Hamaker constants was examined for materials of interest in integrated circuit manufacture. An ultra-high vacuum atomic force microscope and an atomic force microscope
operated in a nitrogen environment were used to measure interaction forces between metals, dielectrics, and barriers used
during the metalization portion of integrated circuit manufacturing.
The materials studied included copper, silver, titanium nitride, silicon dioxide, poly(tetrafluoroethylene), and parylene-N. Spheres coated with a material of interest were mounted on AFM cantilevers
and brought into contact with substrates of interest. The interaction force was measured as the cantilever approached the substrate
but before the two surfaces came into contact, and also when the
particle was pulled out of contact with the substrate. The Hamaker constant calculation from the contact measurement is based on an
adhesion model that quantifies the contribution of geometrical, morphological
and mechanical properties of materials to the measured adhesion force. Hamaker constants determined with this new approach compared with values found by using the Derjaguin approximation for a sphere to describe the interaction force as the cantilever approaches the surface. Both approaches produced similar values for most of the systems studied, with variations of less than 10%
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