Standard-cell rail hookup

Hook the standard-cell rows up to the power mesh. The rows and their metal-1 (M1) power rails are fixed by the library: the rail pitch is the row height and the rail width is set by the cells, so you cannot change the rails themselves. What you tune is the connection down to them from the mesh.

Every cell pulls its current along the M1 rail to the nearest point where a mesh strap drops a via array down to that rail. The local IR (current times resistance) drop is the rail travel to that drop plus the via-stack resistance, so it is worst for a cell sitting midway between two drops.

The mesh starts dropping to the rails only rarely and with a single via each, so the mid-row is red.

• Local IR drop under budget - tighten the strap pitch so no cell is far along its rail from a drop, and add vias per drop to lower the via-stack resistance.
• Routing closes - the straps and via arrays sit on tracks the signals need. A very tight pitch and fat via arrays both eat tracks, so do not over-stitch: keep the routing closing.

Balance the two, then Submit design for a score.