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 min_45_width is.

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.

It does not pair a rectilinear wall against an oblique one (a diagonal stroke closing in on a straight stem) — only rectilinear-vs-rectilinear and oblique-vs-oblique pairs are currently measured for width. min_notch had the same limitation for its dual (the empty-space case) until it was closed by adding a mixed rectilinear/oblique pass; the width side of that gap is still open.

Layers

A single layer, layers[0].

Parameters

None — only value (µm).

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.

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