'Virtuoso Meets Maxwell' is a blog series aimed at exploring the capabilities and potential of Virtuoso® RF Solution and Virtuoso MultiTech. So, how does Virtuoso meets Maxwell? Now, the Virtuoso platform supports RF designs, and the RF designers measure the physical and radiation effects by using the Maxwell's equations. In addition to providing insights into the useful software enhancements, this series broadcasts the voices of different bloggers and experts about their knowledge and experience of various tools in the Virtuoso IC-Packaging world along with the nuances of RF, microwave, and high frequency designs. Watch out for our posts on Mondays.

Hello everyone, when we first started our Virtuoso Meets Maxwell series, Kerry Judd wrote two blogs. In one of them, titled TILP! What’s a TILP?, he introduced the concept of a Technology Independent Layout Pcell (TILP). And, in the other one, called Export the Die? What Am I Exporting? To Where?, he explained how a TILP can be created for a Die layout with bumps. Recently, Brian LaBorde talked about bumps in Bumps, Bumps.... Where Are My Bumps? Finally, Steve Lee explained how the Die TILP can be used for Edit-in-Concert, which is the ultimate IC-package-board co-design, in Learn Your Moves – We’re Doing an Edit-in-Concert. All of these blogs introduce some of the latest and greatest features of the Virtuoso RF Solution.

However, if you have one of those Die layouts which doesn’t have bumps, but rather use pad shapes and labels to identify I/O locations, then you might be feeling a bit left out of all of this jazz and tango. Hence, today, I am writing to tell you that, fear not, we have a solution for your Die as well.

Is it common to have a Die layout without bumps? Yes, it is quite common. Although, many Die layouts done today use bump cells to identify I/O locations, still yet many Die layouts don’t. Also, if you’re using a Die layout that was designed earlier (let’s remember that Die layouts have been done for nearly 30+ years, and back then, bump cells didn’t exist), then the chances are high that, in your layout, the I/O locations are identified by labels overlapping metal shapes. Finally, note that in many cases these Die layouts have already been taped out, and there will be a high probability that the layouts cannot be modified to replace pad shapes with bump cells—the Die layout will have to be explored as-is. Hence, the Virtuoso RF Solution supports a flow to export a Die layout with pad shapes and overlapping labels.

How to export a Die with pad shapes and labels? In his blog, Export the Die? What Am I Exporting? To Where?, Kerry walked us through the details of preparing the Die layout for export. However, when you’re exporting a Die layout with pad shapes, there is very little preparation. The only thing you need to know is where are the pad shapes and labels, i.e., in which metal layer and purpose pair (LPP). Also, ensure that along with the layout view, there are schematic and symbol views for the Die too. To export the shape-based die, refer to the following steps or see Exporting the Shape-Based Die.

Step 1

The picture below shows an example of a simple Die layout (with just the pad shapes).

When we zoom in close to one of the pad shapes, we see that there is an overlapping label. Note that in case multiple labels straddle a shape, which label overlaps which shape is found out from the origin of the label, not the bounding box.

Now, let’s check the metal layer and purpose of the shape and the label. We can see that the metal shape is on “Metal1T P0” LPP, while the label is also on “Metal1T P0” LPP. We will need this information in the next steps.  

Step 2

On the menu bar of the layout window, click RF-Module – Export Die. It opens the Export Die form.

You can see two tabs in the Export Die form, Inputs and Outputs. On the Inputs tab, choose the Die Interface Type as “Shape with overlapping label”. Then specify the layer where (which LPP) the shape is located and also specify the same for the label. On the Outputs tab, specify the name of the library where the Die TILP, schematic, and symbol will be created for further use in the flow.

Can the TILP for a pad shape based Die be used for Edit-in-Concert? Yes, definitely. If you don’t know or have forgotten what Edit-in-Concert is, please feel free to read Steve Lee’s primer in Learn Your Moves – We’re Doing an Edit-in-Concert. There you will see that for a TILP exported from a bumped Die, synchronized edits/changes between the Die TILP and the actual Die layout happens in the Virtuoso RF Solution.

In the case of a TILP exported from a Die layout with shape-based I/O cells, co-design is possible to the extent that when the pad shape is moved in one fabric (i.e., the package layout with the Die TILP, or the Die layout), you will see that there is a discrepancy between the locations of the pad shape in the Die TILP when compared to the same shape in the actual Die layout. In other words, visual detection of the discrepancy in the locations of the pad shape in the different fabrics is possible, but synchronous movement is not. This limitation is due to the fact that the impacted shape may be a part of one or several hierarchical cells in the Die layout and hence it may not be possible to move that specific shape.

Does Layout Versus Abstract (LVA) Check/Fix work with shape-based Die TILP? The bumped cells support LVA checking and fixing. Using these features, the differences between bump locations and missing bumps can be detected between Die TILP and layout. As a result, changes made outside of Edit-in-Concert can also be detected.

However, for shape-based TILP, LVA Check and Fix currently do not work. In a future release, we plan to make LVA Checking work for shape-based TILP. But, LVA Fixing will not work because of the limitations mentioned in the above Edit-in-Concert part.

That’s it for today. Now you know all there is to know about Die TILP for both bump and shape-based Die layouts. Have a great day!

Related Resources

• Virtuoso RF Solution
• What’s New in Virtuoso (ICADVM18.1 Only)

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About Virtuoso Meets Maxwell

Virtuoso Meets Maxwell series includes posts about the next-generation die, package, and board design flow with a focus on reinventing and optimizing the design process to ensure that the designer remains a designer! Keep watching!

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(Sutirtha) Kabir