Integrated Circuit Layout
From Wikipedia, the free encyclopedia
Integrated circuit layout, also known IC layout, IC mask layout, or mask design, is the representation of an integrated circuit in terms of planar geometric shapes which correspond to the patterns of metal, oxide, or semiconductor layers that make up the components of the integrated circuit.
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[edit] Overview
When using a standard process - where the interaction of the many chemical, thermal, and photographic variables are known and carefully controlled - the behaviour of the final integrated circuit depends largely on the positions and interconnections of the geometric shapes. A layout engineer's job is to place and connect all the components that make up a chip so that they meet all criteria. Typical goals are performance, size, and manufacturability.
The layout must pass a series of checks in a process known as verification.(Clein 2000) The two most common checks in the verification process are Design Rule Checking (DRC), and Layout Versus Schematic (LVS). When all verification is complete the data is translated into an industry standard format, typically GDSII, and sent to a semiconductor foundry. The process of sending this data to the foundry is called tapeout due to the fact the data used to be shipped out on a magnetic tape. The foundry converts the data into another format and uses it to generate the photomasks used in a photolithographic process of semiconductor device fabrication.
[edit] History
In the earlier, simpler, days of IC design, layout was done by hand using opaque tapes and films, much like the early days of PCB design. Modern IC Layout is done with the aid of IC layout editor software, or even automatically using EDA tools, including place and route tools or schematic driven layout tools. The manual operation of choosing and positioning the geometric shapes is informally known as "polygon pushing". Though mask design has been around for over 30 years, it is only in recent times that it has been considered a profession. (Saint 2002)
[edit] References
* Saint, Christopher and Judy. (2002). IC Layout Basics. McGraw-Hill. ISBN 0-07-138625-4
* Clein, Dan. (2000). CMOS IC Layout. Newnes. ISBN 0-7506-7194-7
