In the design of integrated circuits, the most popular format for interchange is the Calma GDS II stream format (GDS II is a trademark of Calma Company, a wholly . Portions of the GDSII Stream Format Manual, Documentation No. B97E, Feb. , reprinted with permission of Cadence Design Systems, Inc., River. GDS II is a database file format which is the de facto industry standard for . The GDSII or Stream file format stores its information in records.

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This enables you to define the maximum number of vertices allowed for one polygon. Although the Advanced Design System has options for re-mapping layer numbers and structure names, it does not have the full ability to overcome the GDSII limitations regarding curved elements.

An example of a common record order see below for record descriptions follows: The GDSII file format can contain multiple top-level instances that may or may not be related to one another. The textfont definition file names may include directory specifiers separated with “: GDSII files were originally placed on magnetic tapes. It is a binary file format representing planar geometric shapes, text labels, and other information about the layout in hierarchical form.

This can be done via the SetupDialog or via a macro. This option is deselected as the default.

Fortunately, the way the database was created enabled users to extend many of the dejure limitations while maintaining defacto compatibility with the actual architectural gdsli. The hex numbers are read backwards, from right to left, with each pair of digits representing a byte.


In some cases, this name does not match that of the imported file. This is done by adding an additional cell to the design with the name LayerNames that contains a text elements on each layer with the layer names.

The first four bytes of a record are the header. GDS II files were originally placed on magnetic tapes.

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The program stores arcs as true arcs. Cells can be nested with no limitation as to how deep the nesting goes though I have yet to see nesting more than 9 levels deep.

The third byte of the vdsii is the record type also known as a “token”. Neither the number of columns nor the number of rows may exceed 32, decimal and both are positive.

The data can be used to reconstruct all or part strewm the artwork to be used in sharing layouts, transferring artwork between different tools, or creating photo masks.

I doubt anyone has had the chutzpah to start using it since. Normalization is a process whereby the mantissa is shifted left one hex digit at a time until its left four bits represent a non-zero quantity. A string giving ranges of layers and datatypes separated by a semicolon. Contains four bytes which specify in database units vdsii extension of a path outline beyond the first point of the path.

This information is used only when reading the data into a new library. Contains the list of layers and data types included in the data file usually as specified by the user when generating the Stream file.

This is 6 bytes for “metal” odd length strings are padded with a null plus 8 for “property” plus 2 times the 2 attributes 4 equals Despite its limited set of features and low data density, it became the industry’s default format for transfer of IC layout data between design tools of different vendors, all of which at that time operated with often incompatible and proprietary data formats.


This is despite the fact that GDSII is not an open industry standard — it was developed by Calma in the 80’s and the ownership of the specification moved from Calma to GE to Valid to Cadence over the years.

GDSII – LayoutEditor Wiki

The size, in layout units, for text in the imported design. If this number is not even, a NULL character 0x00 is added to the end. The third data type is a “Two-Byte Signed Integer”. While other formats have been proposed to replace it and one, OASIS, seems to be gaining some traction GDSII remains by far the main way of describing the physical layout for the masks used to build a chip.

This appendix omits the description of tape formatting, since disk files and disk file images on tape and other media are now the norm []. A negative value for width means that the width is absolute; i. This is another artifact of the 16 bit words that the stream file format assumes. This button invokes the Layer Editor. The following is a list of record types.

SPIE Handbook of Microlithography, Micromachining and Microfabrication

The following records are not supported by Stream Release 3. For Layer Editor options, see Defining Layers. It is an integer between and Two 2 byte integers. A component is flattened into its geometric primitives.