@ sahana: It is a good practise to use Double Width Double Spacing (DWDS) routes in clock network. Double width nets are used to avoid electromigration and double spacing nets are used to avoid
Crosstalk .
@ pavan: In Encounter you can specify non-default rule DWDS for clock tree synthesis.
############### Create NDR for Double Width Double Spacing #############
initNdr
setNdrWidth -layer M1 0.18
setNdrSpacing -layer M1 0.18
setNdrWidth -layer M2 0.2
setNdrSpacing -layer M2 0.2
setNdrWidth -layer M3 0.2
setNdrSpacing -layer M3 0.2
setNdrWidth -layer M4 0.2
setNdrSpacing -layer M4 0.2
setNdrWidth -layer M5 0.2
setNdrSpacing -layer M5 0.2
setNdrWidth -layer M6 0.2
setNdrSpacing -layer M6 0.2
setNdrWidth -layer M7 0.2
setNdrSpacing -layer M7 0.2
setNdrWidth -layer M8 0.8
setNdrSpacing -layer M8 0.8
setNdrWidth -layer M9 0.8
setNdrSpacing -layer M9 0.8
setNdrSpacing -hardSpacing 1
createNdr DWDS
Specify width and spacing double than that is given in LEF for each metal layer. Also check the name of layer in LEF it may METAL rather simply M. Paste it in a file. Use this file as PLUG for CTS.
It will use DWDS rule only for CTS.