Chapter VI: ADVANCED EDITING

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Polygon Editing

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For some primitive nodes, it is not enough to rotate, mirror, and scale. These primitives can to be augmented with a trace, which is a polygonal description. The Polygon Edit command of the Edit menu is used to create, delete, and move individual points in a node's trace.

There are quite a few primitive nodes that make use of trace information. The MOS transistors can use trace information as the serpentine path of the gate (polysilicon) layer. Also, all of the pure-layer nodes in the IC layout technologies can be described polygonally. The pure-layer nodes are those in the New Pure-Layer Node command of the Edit menu (they contain only one layer and have the word "-Node" at the end of their names). For example, the node called Metal-Node in nMOS looks like a rectangle of the Metal layer until you add trace information. With trace data, this node can take any shape. Finally, the Artwork technology has nodes that use trace information: Opened-Solid-Polygon, Opened-Dotted-Polygon, Opened-Dashed-Polygon, Opened-FarDotted-Polygon, Closed-Polygon, Filled-Polygon, and Spline.

To manipulate trace information on the currently highlighted node, use the Polygon Edit command of the Edit menu. After issuing this command, the selection button is used to select and move a vertex on the trace, and the creation button adds a new point after the selected vertex. Use the Erase command of the Edit menu (or the Delete key) to delete the highlighted trace point. The Rotate and Mirror commands of the Edit menu change to Rotate about Point and Mirror about Point which allow the entire node to pivot about the currently selected point. Finally, the Get Info command of the Info menu changes to Get Trace Info and displays a dialog which allows precise manipulation of the data.
Figure 6.9

When done editing the trace, use the Exit Polygon Edit command (in the same location as Polygon Edit was in the Edit menu).


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