Technology File Layer Block Keywords: Physical Properties

The following keywords can appear only in physical layer fields, and they mostly specify physical material properties, or electrical parameters, used in various ways by the extraction system.

Many of these parameters are redundant or incompatible with each other. Warning messages may be issued when incompatibilities are detected, however unused information is usually simply ignored and does no real harm. In particular, there are two basic groups, those keywords that apply to conductors, and those that apply to insulators. Mixing these parameters on the same layer will likely generate a warning.

All of these settings can be entered with the Edit Tech Params command in the Attributes Menu and then written to disk with the Save Tech command in the Attributes Menu, or be entered with a text editor directly into the technology file.

Planarize [y| n]
This specifies whether or not a layer is planarizing. This is used by the three-dimensional layer sequence generator when creating layer sequences for the capacitance extraction interface. The Planarize keyword can be applied to prevent planarization of layers that are planarized by default, or to force planarizing of layers that don't normally have this property. See the description of the sequence generator in 12.8 for a description of planarization, and which layers are planarized by default.

Thickness thickness
This keyword supplies the film thickness of the corresponding deposited film. The thickness is given in microns. This can be applied to any physical layer.

FH_nhinc nhinc
This keyword applies to the FastHenry interface, and may be applied to conducting layers. This specifies the nhinc parameter to horizontal segments (parallel to the substrate) with thinkness equal to the layer thickness (as given with the Thickness keyword). This is the number of filaments contained in the segment, which can account for skin or penetration depth of conductors on the layer, in the vertical direction. The value given must be an integer 1 or larger. See the FastHenry documentation for more information about the nhinc parameter.

FH_rh rh
This keyword applies to the FastHenry interface, and may be applied to conducting layers. This specifies the rh parameter, which is the ratio of heights between adjacent filaments. The default ratio is 2.0. Note that this applies only when the number of filaments is larger than one. See the FastHenry documentation for more information about the rh parameter.

At most one of the following two keywords (Rho and Sigma) should be used.

Rho resistivity
This keyword supplies the resistivity, in MKS units (ohm-meters), of the corresponding conducting film. If Rsh (below) and Thickness are both given, then the resistivity is already available and this keyword is redundant. Supplying this keyword overrides the Rsh*Thickness value for the resistivity, when resistivity is used explicitly in the extraction system (in the inductance/resistance extraction interface).

Sigma conductivity
This keyword supplies the conductivity, in MKS units, of the corresponding conducting film. This is converted to resistivity (1.0/conductivity) internally, i.e., it is equivalent to giving Rho.

Rsh ohms_per_square
The single parameter is a floating point number giving the ohms per square value of the conducting material. This is used in computation of the resistance value of resistor devices. If Rho or Sigma is given, and also Thickness, then the sheet resistance is already available and this keyword is redundant. Supplying this keyword overrides the Rho/Thickness value for sheet resistance.

Tau tau
This is the Drude relaxation time for resistive layers, as accepted by current releases of FastHenry. This enables extraction of the parasitic inductance of resistors, which can become appreciable for some materials at low temperature. This parameter is used only when creating FastHenry input.

EpsRel diel_constant
This keyword supplies the relative dielectric constant of insulating layers.

Capacitance units_per_sq_micron [units_per_micron]
This enables computation of the capacitance of a conductor group on the present conducting layer. The first parameter is a floating point number giving capacitance per square micron. The optional second parameter (default 0) is the edge capacitance, per micron. The extracted capacitance is the conductor group area multiplied by the first parameter, plus the conductor group perimeter length multiplied by the second parameter, if given. The capacitance for each wire net is computed during extraction, and will be printed (if enabled) in the physical netlist output file.

The keyword ``Cap'' is accepted as an alias for ``Capacitance''.

Lambda pene_depth
This keyword specifies the London penetration depth of superconducting conductors, in microns. When Lambda is given, Rho/Sigma (if given) represents the conductivity due to unpaired electrons from the two-fluid model.

Tline grnd_plane_layer [diel_thick diel_const]
This keyword will enable use of a microstrip model which computes transmission line parameters. A microstripline geometry is assumed, with an object on the present layer forming a strip over an infinite ground plane layer, separated by a homogeneous dielectric of constant thickness. No account is taken of ``real'' geometry, except for the dimensions of the strip on the present layer.

The first argument is the name of a layer assumed as the ground plane. Both the present layer and the ground plane layer must be conductors and have Thickness and, if superconductors, Lambda defined. Non-superconductors are treated as perfect conductors.

The second argument is the assumed height, in microns, of the intervening dielectric. The third argument is the relative dielectric constant. If either or both of these arguments is missing or given as ``0'' (zero), then Xic will search for a layer with the Via keyword set that contains the present and the ground plane layers, and obtain the missing values from that layer.

Antenna float_value
This keyword applies to the !antenna command, and is meaningful on conducting layers. The float_value is a threshold antenna ratio, as explained for the !antenna command. The value is effectively passed to that command as a default for the layer.