E
Geometry Changes in Virtuoso Releases
This chapter contains information about the geometry changes that can occur in fluid guard ring (FGR) instances when you migrate to newer releases of Virtuoso. FGRs are Pcells that Virtuoso dynamically evaluates; therefore, bug fixes and enhancements to the FGR code can result in geometry changes to the FGR instances for a given set of parameters.
IC6.1.5 ISR15
Fluid guard rings losing contacts in IC6.1.5 ISR15 and ISR16
IC6.1.5 ISR15 introduced a feature that automatically removes corner contacts from fluid guard ring instances when the user specifies a metal or diffusion enclosure value that is less than the larger value of the associated minOppExtension constraint. In some scenarios, Virtuoso removed more contacts than necessary.
Affected releases:
Fixed in:
IC6.1.6 ISR3 and ICADV12.1 ISR5
Create Guard Ring form does not retain previously entered values
The Create Guard Ring form for an existing FGR device did not retain the previously entered values when those were technology rule complaint, but were less than the default values specified in the Install Guard Ring form.
Affected releases:
Fixed in:
DRC violation for the implant layer
When the removal of corner contacts from FGR instances feature was introduced in IC6.1.5 ISR15, the allowable limit for the enclosure of the implant layer was reduced to the minimum of the two minOppExtension values, one for each side. This in turn induced DRC violation for the implant layer.
After the fix for this undesirable consequence, the minimum allowed enclosure value for the implant layer will be the maximum of the two minOppExtension values given for the diffusion and implant layer.
Affected releases:
Fixed in:
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