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 third byte is the record type.
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An example of a common record order see below for record descriptions follows: Reading the first line below, we see that the file begins with the bytes 00 06 00 02, telling us that the first record contains 6 bytes, that the first record is type 00 the headerand that record contains data of type 02 two-byte signed integer. Objects in the cell are assigned to “layers” of the design.
The fifth through last bytes of a record are data. If this record is omitted, then the element is assumed to have no reflection and dtream magnification and angle are assumed to be non-absolute. The name of font 0 starts the record, followed by the remaining 3 fonts.
As a workaround it is possible to save polygons in multi-records and avoid that limit. The first two bytes of the record header contain a count in eight-bit bytes of the total record length.
This option is useful when your post-processor does formag support or correctly translate hierarchy in GDSII Stream files. If either library is not named, its place is filled with nulls.
This, along with the record length, tells the parser what to expect in the rest of the record. The value of the boxtype must be in the range of 0 to ggdsii There may be more than one piece of data, but the rest of the record will be of this type. Same basic thing as a two byte integer, but with four bytes. However it is possible to save such large polygon in multiple blocks.
GDSII – LayoutEditor Wiki
It is this nesting and hierarchy that allow one to describe an IC with one billion polygons using a database on the order of 5 GBytes Two 2 byte integers. Note Because the GDSII stream is a block-structured binary file, it can easily be corrupted when transferring the file from one system to another. A string giving ranges of layers and datatypes separated by a semicolon. The fifth data type is the “Four-Byte Real”.
SPIE Handbook of Microlithography, Micromachining and Microfabrication
For an 8-byte real, the mantissa is in bits 8 to This page was last edited on 27 Novemberat Validate File A file validation is performed after any save operation. An example MASK list looks like this: A component is flattened into its geometric primitives. Any opinions, findings, conclusions or recommendations expressed in this material are those of the author s and do not necessarily reflect the views of the National Science Foundation.
If new layers are added, the importer saves the revised layer definition file to disk. The first and last point of a boundary must coincide. If it is set, then reflection about the X axis is applied before angular rotation. In the MASK list, data types are separated from the layers witha semicolon. This information is used only when reading the data into a new library. All other bits are currently unused and must be cleared to 0. The third data type is a “Two-Byte Signed Integer”. I suspect that they did this due to the modest computers that they had to work with.
Perhaps the Calma people were thinking of gesii needs? There may be more than one mask in a stream file. The name for the first reference library starts at byte 0 and the name of the second library starts at byte 45 decimal. The first is “No data present”. Four-byte signed integer 3.
GDSII Stream File Translator
Neither the number of columns nor the number of rows may exceed 32, decimal and both are positive. Bits 12 and 13 specify the vertical presentaton 00 means top, 01 means middle, and 10 steam bottom.
Square ended paths 1: The third byte of the header is the record type also known as a “token” shown below, and the fourth byte is the data type. The current design in memory is modified as well with any save operation. Geometrical objects may also be tagged with “datatypes”, which can be used for any purpose, but are most commonly used to group together similarly sized objects for compensation of the proximity effect.
This marks the end of a structure. Two-byet signed integer 2. After the length record follows a record type and a data type byte.