Disclosed is a procedure for bottom-up fill of electroless copper film in
sub-micron integrated circuit features. By repeatedly placing an
integrated circuit wafer in an electroless bath, a transient period of
time of accelerated growth in the feature is repeated to achieve many
small layers of deposition, each of which is thicker near the base of the
feature. The net result is filing of the feature from the bottom-up fill
without formation of voids. The electroless bath employed to form the
continuous electroless copper film may include a reducing agent, a
complexing agent, a source of copper ions, a pH adjuster, and optionally
one or more surfactants and/or stabilizers.