i have to do eco in magma previous design is done with 6 metal layers
but eco should be done in 4 metal layers when i am doing force metal layers with highest MET4 it is doing new nets routing upto MET4 but changing other nets to MET5 is there any other way to do that??
If you are using the same process (i.e. it is still a M6 process, but you want to use only up to M4), then I suggest that you remove all route and then re-route everything again.
If you are switch to another technology (i.e. a M4 process), than I think you shoul d get the M4 volcano, port the placement to the new process uisng the def interface, and re-route the design. Note that in alot of process the top metal layer has double or higher pitch than the lower metal layer. Also, the macro placement for M6 process might not be suitable for a M4 process.