Structures and methods are provided which include a selective electroless
copper metallization. The present invention includes a novel methodology
for forming copper vias on a substrate, including depositing a thin film
seed layer of Palladium (Pd) or Copper (Cu) on a substrate to a thickness
of less than 15 nanometers (nm). A number of via holes is defined above
the seed layer. A layer of copper is deposited over the seed layer using
electroless plating to fill the via holes to a top surface of the
patterned photoresist layer. The method can be repeated any number of
times, forming second, third and fourth layers of copper. The photoresist
layers along with the seed layers in other regions can then be removed,
such as by oxygen plasma etching, such that a chemical mechanical
planarization process is avoided.