Python package for EDA / lithography mask design.
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Masque README

Masque is a Python module for designing lithography masks.

The general idea is to implement something resembling the GDSII file-format, but with some vectorized element types (eg. circles, not just polygons) and the ability to output to multiple formats.

Installation

Requirements:

  • python >= 3.11
  • numpy
  • klamath (used for GDSII i/o)

Optional requirements:

  • ezdxf (DXF i/o): ezdxf
  • oasis (OASIS i/o): fatamorgana
  • svg (SVG output): svgwrite
  • visualization (shape plotting): matplotlib
  • text (Text shape): matplotlib, freetype

Install with pip:

pip install 'masque[oasis,dxf,svg,visualization,text]'

Overview

A layout consists of a hierarchy of Patterns stored in a single Library. Each Pattern can contain Refs pointing at other patterns, Shapes, and Labels.

masque departs from several "classic" GDSII paradigms:

  • Layer info for Shapess and Labels is not stored in the individual shape and label objects. Instead, the layer is determined by the key for the container dict (e.g. pattern.shapes[layer]).
    • This simplifies many common tasks: filtering Shapes by layer, remapping layers, and checking if a layer is empty.
    • Technically, this allows reusing the same shape or label object across multiple layers. This isn't part of the standard workflow since a mixture of single-use and multi-use shapes could be confusing.
    • This is similar to the approach used in KLayout
  • Ref target names are also determined in the key of the container dict (e.g. pattern.refs[target_name]).
    • This similarly simplifies filtering Refs by target name, updating to a new target, and checking if a given Pattern is referenced.
  • Pattern names are set by their containing Library and are not stored in the Pattern objects.
    • This guarantees that there are no duplicate pattern names within any given Library.
    • Likewise, enumerating all the names (and all the Patterns) in a Library is straightforward.
  • Each Ref, Shape, or Label can be repeated multiple times by attaching a repetition object to it.
    • This is similar to how OASIS reptitions are handled, and provides extra flexibility over the GDSII approach of only allowing arrays through AREF (Ref + repetition).
  • Labels do not have an orientation or presentation
    • This is in line with how they are used in practice, and how they are represented in OASIS.
  • Non-polygonal Shapes are allowed. For example, elliptical arcs are a basic shape type.
    • This enables compatibility with OASIS (e.g. circles) and other formats.
    • Shapes provide a .to_polygons() method for GDSII compatibility.
  • Most coordinate values are stored as 64-bit floats internally.
    • 1 earth radii in nanometers (6e15) is still represented without approximation (53 bit mantissa -> 2^53 > 9e15)
    • Operations that would otherwise clip/round on are still represented approximately.
    • Memory usage is usually dominated by other Python overhead.
  • Pattern objects also contain Port information, which can be used to "snap" together multiple sub-components by matching up the requested port offsets and rotations.
    • Port rotations are defined as counter-clockwise angles from the +x axis.
    • Ports point into the interior of their associated device.
    • Port rotations may be None in the case of non-oriented ports.
    • Ports have a ptype string which is compared in order to catch mismatched connections at build time.
    • Ports can be exported into/imported from Labels stored directly in the layout, editable from standard tools (e.g. KLayout). A default format is provided.

Glossary

  • Library: A collection of named cells. OASIS or GDS "library" or file.
  • Pattern: A collection of geometry, text labels, and reference to other patterns. OASIS or GDS "Cell", DXF "Block".
  • Ref: A reference to another pattern. GDS "AREF/SREF", OASIS "Placement".
  • Shape: Individual geometric entity. OASIS or GDS "Geometry element", DXF "LWPolyline" or "Polyline".
  • repetition: Repetition operation. OASIS "repetition". GDS "AREF" is a Ref combined with a Grid repetition.
  • Label: Text label. Not rendered into geometry. OASIS, GDS, DXF "Text".
  • annotation: Additional metadata. OASIS or GDS "property".

TODO

  • Better interface for polygon operations (e.g. with pyclipper)
    • de-embedding
    • boolean ops
  • Tests tests tests
  • check renderpather
  • pather and renderpather examples