Re: dummy metal fill ?
Thnks
I understood ur points.
But the dummy Met fill tht u r talking is remedy fr removing thickness variation due to absence of metal.
But I was refering to dummy Met fill , which is used to compensate fr -ve effects produced by CMP (chemical-mechanical polishing).
Now Read following ..
"" For copper, the pattern for the metal traces is etched into the
ILD and copper is electroplated into the newly created trenches. The excess copper material is removed in
a chemical-mechanical polishing step. As a result of this process, variations in wafer height may appear in
areas where the metal density is not uniform.
*(1) Areas where wide metal lines exist can experience erosion, a
condition where too much copper material is removed.
*(2) In locations where the space between metal lines is
smaller, dielectric dishing can occur. The result is greater electrical variation
So To correct for planarity issues, rule-based metal fill is a common approach for inserting dummy metal fill to
achieve uniform metal distribution and adequate planarization ""
Question :: so I m not understanding how excess dummy fill is helping to resolve the problems (1) & (2) ??
Thnks..