VLSI drawings transferring limitations (AKA

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VLSI drawings transferring limitations (AKA
conversion problem)
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Pattern transferring flowchart

• Preparation with drawing software (AutoCAD,
  LEdit, CleWin, LASI)

• If necessary, conversion to JEOL supported file
  formats Calma GDS-II (stream), J01 (local)

• JEOL-51

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File formats

• DXF is AutoCAD Drawing Interchange Format (ASCII
  or binary) (Win)
• CIF (Caltech Intermediate Format) supported by
  CleWIN (Win)
• LASI TLC File Format (open!) (Win, GNU)
• Calma GDS-II (stream) standard file format for
  transferring / archiving 2D graphical design data
  (Win, Sun, Unix, GNU)
• JEOL01 custom format, has many limitations

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AutoCAD-DXF

• The DXF format is a tagged data representation of
  all the information contained in an AutoCAD
  drawing file
• Virtually all user-specified information in a
  drawing file can be represented in DXF format.

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Calma GDS-II (stream)

• Binary format that is platform independent,
  because it uses internally defined formats for
  its data types
• The pattern data is considered to be contained in
  a library of cells. Cells may contain geometrical
  objects such as polygons (boundaries), paths, and
  other cells. Objects in the cell are assigned to
  layers of the design.
• Supports ONLY polygons and wires. The GDS-II
  format specification limits the number of
  vertices per polygon (boundary) and wire (path)
  to not more than 200 pairs of coordinates

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CIF (Caltech Intermediate Format)

• CIF provides a limited set of graphics primitives
  that are useful for describing the
  two-dimensional shapes on the different layers of
  a chip.
• The basic drawing primitives are boxes, circles,
  wires and polygons CIF2.0 donuts and symbol
  scaling

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LASI TLC

• TLC is the file format used by the LASI layout
  editor
• LASI allows converting DXF -gt TLC, TLC lt-gt GDS-II
• TLC uses one file per cell
• A complex layout consists of several TLC files in
  one directory

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Conversion issues

• Compatibility with JEOL e-beam file formats (DXF,
  GDS-II)
• Limitations circuit complexity vs. size and
  compatibility
• Home-made vs. commercial converters most formats
  are protected
• MC2 design rule is based on LEdit and GDS-II
  stream format
• AutoCAD is still powerful and traditional tool to
  create ICs

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DXF -gt J01 -gt J51

• Simplest and reliable way
• Inconvenient for multiple layer layout
• It has many vital limitations

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AutoCAD DXF -gt Calma GDS-II

• Bengt Nilsson, SnL, v3.10 February 2000
• LASI DXF-gtTLC-gtGDS-II
• Cadence (Sun, UNIX)
• LinkCAD (commercial, BAY Tech.INC)

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• Built-in CAD Viewer
• Supported formats ASCII, PostScript, DXF,
  GDS-II, txt-GDS, CIF, TLC and others
• Batch file conversion automatically convert
  several files within minutes.
• Easy selection of file formats and unique setup
  of the format are available.
• Interactively checks and repairs broken and open
  polygons / polylines.
• Flatten command will remove hierarchy from files
  for use in hierarchy sensitive applications.
• Easy selection of cells and layers to be converted

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Design rules

• Rule 1 Use zero-width closed polylines
• Rule 2 Don't use hatching to draw filled
  structures. Use solid lines instead
• Rule 3 Avoid drawing polylines with more than
  200 vertices. GDS-II format does not accept this
• Rule 4 No self-intersection. A polyline may not
  self-intersect. If it does, the result is
  unpredictable (but it can touch itself!)

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Some conclusions

• Optimal conversion strategy depends on complexity
• There are several opportunities to convert files
  from AutoCAD to GDS-II or JEOL01
• If the drawing is created in AutoCAD and very
  complex, LinkCAD affords the best way to convert
  it into GDS-II format