How do you check/analyze routing congestion?

We can analyse Congestion hotspot at different stage:

o    eGR hotspot at preCTS or post-CTS opt - the step just before routing

o   NR-GR hotspot before detail routing

After detail routing we check for DRCs and Shorts.

o   Congestion Maps: Similar to placement congestion analysis, PnR tools generate visual congestion maps based on eGR or NR-GR

o   Overflow Reports: Tools provide reports listing GCells with overflow (demand > supply) and quantifying the overflow percentage or the number of overflowing tracks. This helps pinpoint the most problematic areas.

o   Layer-Specific Analysis: 3D view of congestion map in Innovus allows to check per layer congestion.

o   Identify Causes: Correlate congestion hotspots with design like, bad placement, pin Access, blockages, high density etc.