Methods of forming a metal line and/or via critical dimension (CD) in a
single or dual damascene process on a semiconductor substrate, and the
resist scheme implemented, are disclosed. The method includes forming a
multiple layer resist scheme including a first planarizing layer of a
first type material over the substrate, a second dielectric layer of a
second type material over the planarizing layer, and a third photoresist
layer of a third type material over the dielectric layer. The types of
material alternate between organic and inorganic material. The third
layer is patterned for the metal line and/or via CD. Sequential etching
to form the metal line and/or via critical dimension using a tailored
etch recipe particular to each of the first photoresist layer, the second
dielectric layer and the third planarizing layer as each layer is exposed
is then used. Accurate CD formation and adequate resist budget are
provided.