In a first preferred embodiment of the present invention, conductive
features are formed on a first dielectric etch stop layer, and a second
dielectric material is deposited over and between the conductive
features. A via etch to the conductive features which is selective
between the first and second dielectrics will stop on the dielectric etch
stop layer, limiting overetch. In a second embodiment, a plurality of
conductive features is formed in a subtractive pattern and etch process,
filled with a dielectric fill, and then a surface formed coexposing the
conductive features and dielectric fill. A dielectric etch stop layer is
deposited on the surface, then a third dielectric covers the dielectric
etch stop layer. When a contact is etched through the third dielectric,
this selective etch stops on the dielectric etch stop layer. A second
etch makes contact to the conductive features.