min_space_different_net

Minimum spacing between merged regions that are not electrically the same net.

Semantics

Geometrically identical to min_space — same merge, same tiling, same exact closest-edge distance, same one-violation-per-pair ownership by the gap midpoint. The only difference is a net gate applied to each pair that would otherwise be reported: if both regions resolve to the same net, the pair is not a violation.

This models “different potential” spacing rules, where a process allows conductors at one potential to sit closer than conductors at different potentials. The same-potential minimum is normally a separate, plain min_space rule at a smaller value (for IHP SG13G2: NW.b at 0.62 µm alongside NW.b1 at 1.80 µm).

The net of a region is looked up at its marker point on the rule’s own layer, so layers[0] (and layers[1] in the two-layer form) must appear as a conductor in the PDK’s connect graph. See Architecture for net extraction.

Note

If the rule’s layer is a merged derived layer (a close, as with NW.b1’s NWellMergedNoSRAM), put that merged layer in the connect graph rather than the drawn layer. A merged region’s marker can land in a gap the close filled in — inside the merged layer, but outside any drawn shape — where a lookup on the drawn layer would not resolve.

Every uncertain case fails conservative and reports, exactly as the plain geometric rule would: a marker that resolves to no region, a layer missing from the connect graph, or a region with no net of its own (an untied, floating well). A wrong or missing net can therefore only ever cost a false positive, never a false clean.

This is a net-aware check: it is skipped with a message when connectivity is disabled (--no-connectivity), and its presence in a deck causes net extraction to run.

Layers

  • Same-layer form: one layer — checks every region against every other region of it.

  • Two-layer form: layers[0], layers[1] — each side’s net is resolved on its own layer.

Parameters

None beyond layers and value (µm, the minimum required gap).

Violation markers

One edge marker per violating pair, drawn across the gap.

KLayout equivalent

None directly. The shipped IHP deck omits its two potential-dependent NWell rules (NW.b and NW.b1) rather than approximate them; expressing this in KLayout needs a Netter-based connectivity extraction driving a separation between per-net region sets.

Example

- id: NW.b1
  check: min_space_different_net
  layers: [NWellMergedNoSRAM]
  value: 1.80