Methods are disclosed for reducing damage to an ultra-low dielectric
constant (ULK) dielectric during removal of a planarizing layer such as a
crosslinked polymer. The methods at least partially fill an opening with
an at most lightly crosslinked polymer, followed by the planarizing
layer. When the at most lightly crosslinked polymer and planarizing layer
are removed, the at most lightly crosslinked polymer removal is easier
than removal of the planarizing layer, i.e., crosslinked polymer, and
does not damage the surrounding dielectric compared to removal
chemistries used for the crosslinked polymer.