Several questions about doing floorplan

Hi

Why v r creating block halo..
on what basis the values are entering in options.

While adding ring, In Ring Configuration, on what basis metal layer are choosing?
In one pdf they are choose METAL4 for top and bottom sides and METAL3 for left and right sides.
For calculating wire & thickness what is the formulae?
This is correct.. wire & thickness = 2X the wire widths and thicknesses in LEF file.

In Adding Stripes, why r choosing METAL2 to create Power stripes?
How to set the Set-to-set distance? i.e specifies distance between two set of stripes connecting power rings..
Too many power stripes create routing blockage which makes routing difficult. Too less power stripes result in poor power distribution to the cells and wastage of wiring resource on lower metal layers.. so how to select the set-to-set distance?

When we need to do SRoute? after CTS or in placement stage itself?

Thanks in advance

Floorplan

Block halos are required because we dont want any standard cells to be placed around the blocks. If they are placed then the router would face difficulty to connect the block pins to any other cells. As router is blocked by these standard cells.

Added after 3 minutes:

One should always prefer the highest metal layer allowed to route the core rings because they have got more thickness compared to others. This will reduce the resistance of these rings and there by IR drop is reduced.

I am not sure about the calculations. If some one knows please help.

Re: Reg: Floorplan

apart from avoiding the stdcells placement near the ebbs, the halo also helps in maintaining the N-WELL spacing