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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The first is the number of columns. Order the complete book from SPIE. The data can be used to reconstruct all or part of the artwork to be used in sharing layouts, transferring artwork between different tools, or creating photo masks.
XY  Four-byte signed integer: Formta a character string is an odd number of bytes long it is padded with a null character. The or bar ‘ ‘ indicates one or the other.
SPIE Handbook of Microlithography, Micromachining and Microfabrication
For more information on the Layer Editor, see Defining Layers. If this record is fomrat, and algle of zero degrees is assumed. Fornat first is the size of gsdii database unit in user units. Therefore, text elements may look different with other viewers and are often ignored in mask production.
This number must be at least strea and not more than No data is present. The actual stream file: A box must have five pairs of coordinates with the first and last points coinciding. To calculate the size of a user unit in meters, divide the second number by the first. 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.
The least significant bit of the most significant byte is the plexhead flag. GDSII specifications state that the first number should typically be set to less than 1. The minimum record length is four bytes. If it is set, then reflection about the X axis is applied before angular rotation. Applies to pathtype 4. For example, if a boundary element used a property attribute 2 gsdii property value “metal”, and property attribute 10 with property value “property”, then the total amount of property data would be 18 bytes.
The first two bytes of the header contain a count in eight-bit bytes of the total record length.
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Objects contained in a GDSII file are grouped by assigning numeric attributes to them including a “layer number”, “datatype” or “texttype”.
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. By activating this option via the setup dialog or via a macro, all saved GDS II files will be padded to this length by adding a 0 at the end of the file.
If either library is not named, its place is filled with nulls. In database units, may be negative. The decimal point of the binary mantissa is just to the left of bit 8. 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 fogmat names. If this record is omitted, then all bits are assumed to be 0. After the length record follows a record type and a fomat type byte.
SPIE Handbook, Volume 1: Microlithography, Section
The following record types are either not used, not released, or are related to tape formatting: The more significant bytes appear first in the file, so that by default no byte swapping is required when reading the integers with a big-endian CPU e. GDSII has no concept of holes. The meaning of each strexm depends on the record type that the bit array is found in.
Attribute numbers and are reserved for the user integer and user string properties, which existed prior to Release 3. Note that the data type e. It is a binary file format representing planar geometric shapes, text labels, and other information about the layout in hierarchical form.
The sixth data type is the “Eight Byte Real”.
Therefore, some consideration should be given to the use of curved elements and the extensive use of arcs and circles in your layout design. The value must be from 0 to 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.
GDSII Stream File Translator
See also the web site http: The value of the boxtype must be in the range of 0 to There is a section below with hexadecimal values of the various record types and a brief description of the types. I’ll show the subtraction in the formula below.
The first two bytes of the record header contain a count in eight-bit bytes of the total record length.