setRC.tcl via resistance unit

[kareefardi]

I was looking at flow/platforms/sky130hd/setRC.tcl and noticed that for via resistance, for example via:

OpenROAD-flow-scripts/flow/platforms/sky130hd/setRC.tcl

Line 12 in 84cc887

set_layer_rc -via via -resistance 4.5E-3

(see number in techLef https://github.com/efabless/skywater-pdk-libs-sky130_fd_sc_hd/blob/4dbe3954e308edb6d65a15d1683ddca6eabdc369/tech/sky130_fd_sc_hd__nom.tlef#L138) is converted from dbu

If I run the following script (full testcase: test-case.tar.gz:

foreach layer [$::tech getLayers] {
    if { [$layer getType] == "CUT" } {
        set layer_name [$layer getName]
        set res [$layer getResistance]
        puts "$layer_name $res"
    }
}

set_layer_rc -via mcon -resistance 9.249146E-3
set_layer_rc -via via -resistance 4.5E-3
set_layer_rc -via via2 -resistance 3.368786E-3
set_layer_rc -via via3 -resistance 0.376635E-3
set_layer_rc -via via4 -resistance 0.00580E-3

puts "###############"
foreach layer [$::tech getLayers] {
    if { [$layer getType] == "CUT" } {
        set layer_name [$layer getName]
        set res [$layer getResistance]
        puts "$layer_name $res"
    }
}

and got the following output:

licon 0.0
mcon 9.3
via 4.5
via2 3.41
via3 3.41
via4 0.38
###############
licon 0.0
mcon 0.009249146
via 0.0045
via2 0.003368786
via3 0.000376635
via4 5.8e-6

Does this mean that the conversion in setRC.tcl is unnecessary?

[kareefardi]

Can anyone verify this?