min_gate_length¶

Purely geometric (no connectivity needed). The minimum width of a region measured between chosen walls — max_gate_length and exact_gate_length bound the same span the other ways: the gate poly’s length where it forms a device gate — as opposed to min_width, which would measure the poly’s width everywhere — and never the channel width W, which the active’s edges set and which are no walls of the poly.

Semantics¶

A gate has two kinds of wall. The ones the poly brought with it stand across the channel, and the distance between them is the gate’s length; the ones the active cut stand at the ends, and the distance between them is the transistor’s width. Both are widths of one region, and which walls take part is the whole difference.

So the rule names the region (layers[0]) and a reference (layers[1]), and runs the facing-wall width scan of min_width over the region, cutting every pair it finds to the stretch along which both walls lie on the reference’s boundary — or, with walls: unshared, along which neither does. A pair with no such stretch is dropped. Collinearity is exact on the grid.

For a poly stripe and a channel mask such as GatPolyOverNsdActivNoTGO (poly ∩ active ∩ N+, outside thick oxide), the stripe’s two long walls lie on the mask’s boundary exactly where they cross the active, and every gate along the stripe is found from the tile it falls in — however long the stripe. For an LDMOS body against its active, the walls unshared with the active are the ones across the channel.

Layers¶

Positional, exactly two:

The region whose width is measured (GatPoly, tgate, an LDMOS body).
The reference whose boundary chooses the walls: a channel mask, the active, comp.

Parameters¶

walls: shared (default) keeps the stretches on the reference boundary; unshared the ones off it.
angle: bent measures only between 45° walls — GF180’s PL.7, the width across a gate that bends.
layer_params: outside: A region the kept stretches must lie outside of — GF180’s NAT.4 reads the native gate’s length off the poly walls that are not under the well.
length: As for min_width, read on the kept stretch: the gate is measured only where the walls it shares with the reference run longer than this — a length rule that binds only channels wider than so much.

Violation markers¶

One edge marker per wall of every under-length span, cut to the stretch the filter kept.

KLayout equivalent¶

poly.edges.and(gate.edges).width(value) — and, for the other options, .not(region) on the edges, edges.inside_part(comp) and with_angle — read on the region rather than on an edge collection, so the material between the walls is known rather than inferred.

Example¶

- id: Gat.a1
  check: min_gate_length
  layers: [GatPoly, GatPolyOverNsdActivNoTGO]
  value: 0.13
- id: PL.2_LV
  check: min_gate_length
  layers: [tgate_pl2_lv, comp]
  value: 0.28
  params:
    walls: unshared
- id: NAT.4
  check: min_gate_length
  layers: [poly_nat_lv, ngate]
  value: 1.8
  layer_params:
    outside: nwell