Patent ID: 7825019

Claim:
A semiconductor structure fabrication method, comprising: providing a structure which includes: (i) a substrate, (ii) semiconductor devices on the substrate, (iii) a first ILD (inter-level dielectric) layer on top of the substrate and the semiconductor devices, wherein the substrate includes a top substrate surface which defines a reference direction perpendicular to the top substrate surface, (iv) N first actual trenches and M first dummy trenches in the first ILD layer, N and M being positive integers, (v) N first actual metal lines and M first dummy metal lines, wherein each first actual metal line of the N first actual metal lines is in a respective first actual trench of the N first actual trenches, wherein each first dummy metal line of the M first dummy metal lines is in a respective first dummy trench of the M first dummy trenches, wherein the N first actual metal lines are electrically connected to the semiconductor devices, wherein the M first dummy metal lines are not electrically connected to any semiconductor device, and wherein the N first actual metal lines and the M first dummy metal lines provide an essentially uniform pattern density of metal lines across the first ILD layer, and (vi) N first actual diffusion barrier liners and M first dummy diffusion barrier liners, wherein each first actual diffusion barrier liner of the N first actual diffusion barrier liners is in direct physical contact with a corresponding first actual metal line of the N first actual metal lines, and wherein each first dummy diffusion barrier liner of the M first dummy diffusion barrier liners is in direct physical contact with a corresponding first dummy metal line of the M first dummy metal lines; removing the M first dummy metal lines without removing the N first actual metal lines; and forming a dielectric passivation layer on top of the first ILD layer such that the M first dummy trenches are partially but not completely filled by the dielectric passivation layer to form an enclosed space not comprising any solid material within each first dummy trench.