As you incrementally build your design and decompose the layout geometry into masks or colors, you may want to change the color already applied to a shape or a set of shapes. At the same time, you may want the color of some shapes to stay unchanged. So, you lock the color on such shapes, because, by default, color shifting is not permitted on locked shapes. But what about the conflicts that occur when you end up locking the same or a different color on a shape at multiple levels in the hierarchy? Can such hierarchical color locking conflicts be prevented? Or detected? Let’s find out.
What Are Hierarchical Color Locking Conflicts?
There are two types of color locks that you can assign to a shape—a color state (dbLock) and a hierarchical color lock (HCL). While a shape can have only one dbLock, it can potentially have multiple HCLs applied to it from different levels in the hierarchy. A conflict occurs when there are multiple locked color assignments for a shape.
When Do Hierarchical Color Locking Conflicts Occur?
Hierarchical color locking conflicts occur when an HCL exists on a shape that:
- Has an HCL applied to it elsewhere in the hierarchy
- Has a dbLock applied to it in the cell master
- Is part of a locked or partially locked via
Can Potential Hierarchical Color Locking Conflicts Be Prevented?
You can avoid hierarchical color locking conflicts by following a full bottom-up, color-locked flow. Moreover, the coloring engine and the locking tools are designed to prevent you from applying an HCL on top of a shape that is already locked down below in the hierarchy.
However, to check whether you inadvertently locked color on a shape that has an HCL applied to it at a higher level in the hierarchy, you should run the Hierarchical Color Locking check regularly, and correct all errors reported in the Miscellaneous tab of the annotation browser.
Checking for Hierarchical Color Locking Conflicts
The video at the link below demonstrates how to run a Hierarchical Color Locking check on a design. It also illustrates some scenarios that can result in hierarchical color locking conflicts. Click the link now or visit Cadence Online Support later and search for the video title under Video Library.
Using the Hierarchical Color Locking Check
Note: If you don’t have a Cadence Online Support account, you can play the video (mp4) natively in Cadence Help when using Virtuoso ICADV12.3 (base release or later). In the Cadence Help Virtuoso Documentation Library, search for the video title under Video Demos.
Related Resources
Virtuoso Multi-Patterning Technology User Guide
Note: For more information on Cadence products and services, visit www.cadence.com.
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Mita Pant