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Technology File Setup

Setup parallels setup of the three-dimensional layer sequence database (see 12.8), which in turn follows setup of the extraction system (see 16.8). These sections should be consulted for detailed setup information, here we provide some supplemental information.

To the interface, there are two different materials:

Conductors will have one of the following:
  1. Any of the Conductor, Routing, GroundPlane, GroundPlaneClear, or Contact technology file keywords (or their aliases) applied. All of these implicitly give the Conductor keyword.

  2. Any of the Rsh, Rho, Sigma, or Lambda keywords applied with a positive value.

Insulators will have one of the Dielectric or Via keywords applied, and also the EpsRel keyword applied with a value of 1.0 or larger.

In addition, layers that are to be used in the interface as conductors or insulators must have all of the following:

The Dielectric technology file keyword was added to support this interface. This is intended to model an explicit capacitor dielectric, and differs from Via layers in the following ways.

The present interface can take layers in any order. This is in contrast with the original interface, that required layers to alternate conductor/insulator starting with a conductor, and ordering was obtained entirely from Via references and not the layer table order.

After all possible layers from the layer table are sequenced, layers that are not used in the extracted geometry are discarded. Note that dark-field layers are inverted, as we are interested in representing the physical material. Thus, for example no structure in a Via layer (i.e., no vias) in the layout implies the presence of a continuous film of insulating material, so the layer is actually present.

The same layer sequencer is used in the Cross Section command in the View Menu. The cross section display and the interface will always agree on the ordering and planarization of the layers. It is therefor a useful visualization tool when setting up the layers in the technology file.

The Cross Section command is also useful for finding errors. One possible error occurs when not planarizing, and a thin metal layer runs over the edge of a thicker dielectric layer. This will disconnect the metal between the two sides of the step, which will cause a failure in the extraction. Presently, the interface assumes that the number of conductor groups remains the same before and after 3D processing. The disconnection can be easily seen in the Cross Section view.

In addition to the layers that describe material geometry, the interface can make use of a masking layer. This allows only certain specified parts of the current cell to be evaluated. When present, geometry is clipped to objects on this layer before being processed in the interface.

By default, a layer named FCAP with purpose drawing is assumed for the masking layer. Such a layer should be defined in the technology file. It should be given a GDSII mapping to allow saving of work containing the layer to GDSII or OASIS files. As an alternative, the FcLayerName variable can be set to the name of another layer, which will instead provide the masking function.

next up previous contents index
Next: Output File Up: The Capacitance Extraction Interface Previous: Geometry Construction   Contents   Index
Stephen R. Whiteley 2022-05-28