A copper-containing layer suitable for an electrical interconnect in a device
such
as an integrated circuit is created by a procedure in which a trench (104)
is formed through a dielectric layer (102) down to a substrate (100).
A diffusion barrier (106) is provided over the dielectric layer and into
the trench. Copper (108) is deposited over the diffusion barrier and into
the trench. Chemical mechanical polishing is utilized to remove the copper outside
the trench down substantially to the diffusion-barrier material overlying the dielectric
layer. A sputter etch, typically of the reactive type, is then performed to substantially
remove the diffusion-barrier material overlying the dielectric layer. The sputter
etch typically removes copper above and/or in the trench at approximately the same
rate as the diffusion-barrier material so as to substantially avoid the undesirable
dishing phenomenon.
