GDSII

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A rendering of a small GDSII standard cell with three metal layers (dielectric has been removed). The sand-colored structures are metal interconnect, with the vertical pillars being contacts, typically plugs of tungsten. The reddish structures are polysilicon gates, and the solid at the bottom is the crystalline silicon bulk.

GDS II stream format, common acronym GDSII, is a database file format which is the integrated circuit industry de facto standard for IC layout data exchange. It was originally developed by Calma for its layout design software, "Graphic Data System" ("GDS") and "GDS II". Now the format is owned by Cadence Design Systems.

GDS II is a binary file format representing planar geometric shapes, text labels, and some other information - in hierarchical form. The objects are grouped by numeric attributes assigned to them including "layer number", "datatype" or "texttype". While these attributes were designed to correspond to the "layers of material" used in manufacturing an integrated circuit, their meaning rapidly became more abstract to reflect the way that the physical layout is designed.

Initially, GDS II was designed as a format used to control integrated circuit photomask plotting. Despite its limited set of features and low data density, it became the industry conventional format for transfer of IC layout data between design tools of different vendors, all of which operated with proprietary data formats.

GDS II files are the final output product of the IC design cycle, and are given to IC foundries for IC fabrication. These GDSII files were originally placed on magnetic tapes, hence the final moment of the IC design process has become known as tapeout.

As of October 2004, many EDA software vendors have begun to support a new format, OASIS, which may replace GDSII.

With the free tools "gds2pov" ^[1] and POV-Ray ^[2] you can easily convert GDSII data into a nicely rendered 3D view.

"KLayout" is a free GDSII viewer ^[3]. The sourceforge page for "layout" contains a list of various layout viewers^[4].

[edit] Notes

[edit] See also

• Computer Aids for VLSI Design - Appendix C: GDS II Format by Steven M. Rubin
• The GDSII Stream Format by Jim Buchanan
• Ruby GDSII Library for reading, manipulating, and writing GDSII data in the Ruby programming language
• gds2pov for generating 3D scenes of GDSII layouts to render using POV-Ray

[edit] References

* Clein, Dan. (2000). CMOS IC Layout. Newnes. ISBN 0-7506-7194-7