Technology File Standard Via Definitions

Xic provides support for OpenAccess/Virtuoso-style standard vias (see 5.8). These definitions are imported from a Virtuoso ASCII technology file when the ReadCdsTech is used to source a Cadence technology database, if any <tt>standardViaDefs</tt> nodes exist. They will be written to and read from the Xic technology file using syntax described in this section.

Standard via definitions will be written following the derived layers when a new technology file is being created. This is the recommended location when hand editing a technology file. The definitions are required to follow the layer definition blocks of any layers used, but otherwise location in the technology file is flexible.

The syntax for a standard via definition is as follows.

StandardVia viaName layer1 layer2 cutLayer cutWidth cutHeight cutRows cutCols \
cutSpace_x cutSpace_y layer1Enc_x layer1Enc_y layer2Enc_x layer2Enc_y \
layer1Off_x layer1Off_y layer2Off_x layer2Off_y originOff_x originOff_y \
[ implant1 imp1Enc_x imp1Enc_y [ implant2 imp2Enc_x imp2Enc_y]]

The terms correspond to the options shown in the Via Creation panel from the Edit Menu, and their effects are described in that section. The definition must appear on a single logical line, but backslash line continuation (as shown) can be employed to break the line for improved human readability.

The line must begin with the StandardVia keyword. The remaining tokens are as follows. All of the numerical values can be altered by the user before placement, the values provided in the definition are the initial defaults. The layer names, however, can not be changed subsequently. All dimensions are in microns.

viaName
This is a unique name for the standard via, and can be any text word that can be used as a cell name. One convention is to use the layer names of the twe conductors, top conductor first, separated by an underscore (e.g., ``M2_M1'').

layer1 layer2 cutlayer
The three tokens that follow are the names of the bottom conductor, the top conductor, and the via layer, in that order. These layers must have been already defined in the technology file.

cutWidth cutHeight
These are floating-point numbers giving the size of the cut in microns. The cut is always rectangular.

cutRows cutCols
These are integers not less than 1, which indicate that the cut should be arrayed according to the numbers of rows and colums given. These are both usually 1 in a standard via definition, representing a minimum via. The user can array the cuts when necessary from the Via Creation panel.

cutSpace_x cutSpace_y
These apply when the cut is arrayed, and provide the edge-to-edge space between cuts in the x and y direction. This is usually a minimum value given by a design rule.

layer1Enc_x layer1Enc_y layer2Enc_x layer2Enc_y
These four dimensions provide the enclosure distance for the bottom (layer1) and top conductor rectangles relative to the cut. The enclosure is the distance that the metal rectangle extends outside of the cut area. This is usually a minimum value given by a design rule.

layer1Off_x layer1Off_y layer2Off_x layer2Off_y
These four dimensions provide offsets for the center of the two conductor rectangles relative to the center of the cut. These values are unlikely to be other than zero.

originOff_x originOff_y
These coordinates provide the origin of the sub-master cell relative to the center of the cut array. It is the location that corresponds to the mouse pointer when a new via instance is placed. These are unlikely to be other than zero.

All of the terms mentioned thus far are required. The remaining terms are optional.

implant1 imp1Enc_x imp1Enc_y
This is the name of a layer followed by two dimensions. If found, an additional rectangle of implant1 is centered over the layer1 (bottom conductor) rectangle. The enclosure values specify the distance the implant extends outside of the conductor, in the x and y directions.

implant2 imp2Enc_x imp2Enc_y
These may follow an implant1 group only. This is the name of a layer followed by two dimensions. If found, an additional rectangle of implant2> is centered over the layer2 (top conductor) rectangle. The enclosure values specify the distance the implant extends outside of the conductor, in the x and y directions.

Standard via definitions successfully read from the technology file will be saved internally, and the definitions can be accessed from the Via Creation panel. The panel allows the default values to be overridden, and new vias to be created and placed. If no stantard via definitions were successfully read, the panel is unavailable and the Create Via button in the Edit Menu is grayed.