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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Two 2 byte integers. This formaat must be at least 2 and not more than The original dataset is not modified. Exactly 1 pair SREF: The size, in layout units, for the text in the exported design. Valid values are 1 – inclusive. There may be from 1 to 32 ACL entries, each consisting of a group number, a user number, and access rights. They sure strram that with the layer numbers and data types. I suspect that sstream did this due to the modest computers that they had to work with.
This moment was fittingly called “tape out” though it is not the original root of the term. An x appears in the box to the left of s elected attributes. The following table summarizes the Bachus Naur symbols: This is not part of the GDS standard, but supported by some viewers. I’ve listed the essential ones here:. Webarchive template wayback links. NODE  No data is present. GDSII limitations can affect how you design your layout.
The least significant bit of the most significant byte is the plexhead flag. An x appears in the box to the left of selected attributes. gdsi
SPIE Handbook of Microlithography, Micromachining and Microfabrication
The decimal point of the binary mantissa is just to the left of bit 8. I suspect that the people at Calma put a lot of thought into creating a file that would be as easy to read in formah parse as possible.
I’ll show the subtraction in the formula below. If this option is activated, that additional cell will not be visible in the LayoutEditor.
B.2 Calma GDS II stream format (GDSII)
Fortunately, the way the database was created enabled users to extend many of the dejure limitations while maintaining defacto compatibility with the actual architectural underpinnings.
This one gets a little more use. Bit 15 rightmost and gdsik remaining bits are reserved for future use and must be cleared. The first two numbers in brackets are the record type and the last two numbers in brackets are the data type see the table above. A text or SREF element must have only one pair of coordinates.
GDSII – Wikipedia
This enormous base of legacy code is probably what is slowing the transition to alternatives in particular OASIS. GDSII has some limitations that may affect your layout, including: This marks the end of a structure. Bits 12 and 13 specify the vertical presentaton 00 means top, 01 means middle, and 10 means bottom. This enables you to exclude one or more layers from the output file by specifying the layer numbers to exclude, separated by commas.
When this is selected, holes are converted to polygons. gdsi
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 strema record contains data of type 02 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. GDS II files were originally placed on magnetic tapes. Bit 14 specifies external data also referred to as “exterior” data.
This page was last edited on 27 Novemberat Different layers typically represent different processing steps for exposure on separate mask plates. These free tools include editors,    viewers,  utilities to convert the 2D layout data into common 3D formats,   utilities to convert the binary format to a human readable ASCII format  and program libraries.
GDS II files can be read as normal files or gzip compressed files without an external decompresser. The minimum record length is four bytes. Objects in the cell are assigned to “layers” of the design. The basic unit of measurement is a nanometer 10 -9 meter Since four byte signed integers are used to describe a coordinate then the integer coordinates can range from from minus 2 31 to plus 2 31 This should be selected for the following conditions:. For every hex digit shifted, the exponent is decreased by one.