The first , you have to find out the power comsumption of the memory you use in your design.
The second, you have to know the current and metal width ratio.
Then you will understand how width of metal you need.
thank nemolee!
As you said, I can read power consumption in data sheet generated by mem compiler and current density in per metal layer.
But there are some connection from power strap and mesh to mem's power ring, the assumption is rational that current in per connection point devided by 2 ?