min_width¶

Every place metal narrows below value (measured wall-to-wall, perpendicular to the metal’s run) is a violation. The most common width rule — e.g. IHP’s TM2.a (TopMetal2 minimum width).

Semantics¶

Runs the shared facing-edge width scan (shared with max_width and exact_width) over each merged region’s contours (outer ring and holes):

Rectilinear pass: every vertical edge is classified as a left or right wall of metal (by which side the fill is on); at each distinct y-band, adjacent left/right walls are paired and the gap between them is the metal’s width there. The same is done for horizontal edges, sweeping x-bands, to catch vertical spans. Together these two passes measure ordinary Manhattan metal widths in both directions.
Oblique pass: pairs of mutually anti-parallel diagonal edges (same absolute angle, opposite direction) are measured directly, so a 45° trace’s width is caught too — this pass always runs, even for a plain min_width rule; it isn’t gated on a “bent length” the way angle: bent is. Anti-parallel is read as far as the grid can say: a boolean cuts a 45° wall and rounds its new end to the DBU, so the two sides of one bar can come out 0.05° apart, and a pair whose gap drifts by under a DBU and a half over the run it shares still bounds a width.
Mixed pass: a diagonal edge facing an axis-aligned one — the chamfered corner of a well against the straight wall opposite — is measured at its closest approach.
Corner pass: two facing walls whose projections do not overlap — the steps of a jog, the two stubs either side of a chamfer — are measured from the near end of one to the near end of the other, as KLayout’s euclidian metric reads them.
Pinches and acute corners: a vertex the layer touches itself at (two pieces corner to corner, a notch tip on a straight wall, a contour through one point twice) is a width of zero, reported as a point; so is a corner with less than a right angle of material in it, since the wedge narrows to nothing at the tip.

A width is only reported once its projected overlap between the two walls is real (not just touching at a point), and only from the tile whose core contains the gap’s midpoint, so a wall pair straddling several tiles is reported exactly once.

This scan measures facing walls of one region, unlike min_dim, which measures a whole region’s bounding box — a min_width rule catches a narrow neck anywhere in an irregular shape; min_dim only catches the shape’s bounding box being too narrow overall.

The comparison is exact. The rule’s µm value is put on the grid once — rounded up for a minimum, down for a maximum, to nearest for an exact width — and after that an axis-aligned span is compared as the integer it is, an oblique one squared as a ratio of integers. A 45° bar drawn 226 DBU apart in y is 159.81 DBU wide, and a 160 rule reports it.

Layers¶

A single layer, layers[0].

Parameters¶

angle: bent measures only the 45° runs. A fab may ask more width of a diagonal than of a straight trace, since the grid resolves a diagonal as a staircase; that rule sits beside the plain one with its own value.
length: The run (µm) two facing axis-aligned walls must share — the projection of one onto the other, over the whole walls — before their width counts, KLayout’s projection_limits: a rule that binds only lines longer than so much. On a 45° pair, with angle: bent, it is each wall’s own length instead - “a bend longer than 0.39” is the bend’s wall, and IHP’s deck takes the 45° edges of at least that length and measures between them; a band drawn with square ends has its walls offset along their run by its width, so the shared stretch understates the bend. With a length required, the readings that have none (across a corner, at a pinch or acute tip, between a chamfer and a wall) are off. Optional, defaults to 0.

Violation markers¶

One edge marker for each of the two facing walls of any width below value (so two markers per violation location, one on each wall), at the actual wall geometry. A pair of walls is one violation along the whole stretch they face each other, however many other corners of the shape fall alongside it, and whatever the tiling: the pair is reported by the tile holding the lowest (then leftmost) end of the stretch, a vertex every tile’s copy of the shape has where it has it at all, where the stretch’s far end depends on which drawn shapes reach the tile’s zone.

KLayout equivalent¶

Region#width(value) — KLayout’s own facing-edge width check, including its handling of 45° edges under the default (90°) angle limit.

Example¶

- id: TM2.a
  check: min_width
  layers: [TopMetal2]
  value: 2.00
- id: M2.g
  check: min_width
  layers: [Metal2]
  value: 0.24
  params:
    angle: bent
    length: 0.50