The present invention pertains to apparatus and methods for planarization
of metal surfaces having both recessed and raised features, over a large
range of feature sizes. The invention accomplishes this by increasing the
fluid agitation in raised regions with respect to recessed regions. That
is, the agitation of the electropolishing bath fluid is agitated or
exchanged as a function of elevation on the metal film profile. The
higher the elevation, the greater the movement or exchange rate of bath
fluid. In preferred methods of the invention, this agitation is achieved
through the use of a microporous electropolishing pad that moves over
(either near or in contact with) the surface of the wafer during the
electropolishing process. Thus, methods of the invention are
electropolishing methods, which in some cases include mechanical
polishing elements.