Author's Latest Posts

The Pitfalls Of Auto-Stitching In Double-Patterning

Ever since the first double-pattern (DP) odd-cycle error ring was produced on a layout, designers have longed for a magic solution to solve it. Traditionally, the first approach to fixing an odd-cycle error was to move a polygon or a polygon edge to increase spacing to an adjoining polygon in the cycle. Alternatively, you could remove a polygon altogether, or split it into two pieces. All of th... » read more

Colorless vs. Colored Double-Patterning Design Flows

Colored vs. Colorless double patterning design flows—do you know which one is best for your design? What options does your foundry allow? Do you debug one differently from the other? In this short video, I’ll demonstrate the differences between colored and colorless DP design flows, and explain the options and potential pitfalls of each approach. With a better understanding of how to design... » read more

ECOs and Multi-Patterning: It Can Be Done

By David Abercrombie and Alex Pearson A lot has been written and discussed about how to decompose (color) layouts for advanced process nodes that require multi­patterning (MP). However, one topic that has been sorely ignored is how to efficiently make changes to designs that are already colored, or even taped out and processed. We tend to act like all designs work out the first time through... » read more

When And How Should I Color My DP layout?

Designers working with advanced process technologies that require double patterning often find themselves puzzling over the best way to setup or optimize their design flows to ensure their layouts can be decomposed without time-wasting mistakes. Because manual coloring can be challenging even for experienced engineers, many prefer to use automated coloring solutions. But when is the best time a... » read more

Resetting Expectations On Multi-Patterning Decomposition And Checking

As I said in Part 1 of this topic, it never ceases to amaze me how much confusion and misunderstanding there is when it comes to multi-patterning (MP) decomposition and checking. That entire first article only focused on the typical subjects I’ve had to discuss with customers regarding double-patterning (DP). I have to tell you that with the deployment of triple-patterning (TP) and quadruple-... » read more

Resetting Expectations On Multi-Patterning Decomposition And Checking

It never ceases to amaze me how much confusion and misunderstanding there is when it comes to multi-patterning (MP) decomposition and checking. I sometimes forget just how new a topic it is in our industry. Because of this short-lived history, and the limited time designers have had to acquire any detailed understanding of its complexity, there appears to be some serious disconnect in expectati... » read more

Case Studies in P&R Double-Patterning Debug

In my last article, we looked at some case studies of the unique types of issues related to double patterning (DP) that place and route (P&R) and chip finishing engineers have to deal with. I’ve got some more interesting case studies to show you this time. In modern P&R designs, the metal routes on a particular layer are unidirectional (or at least primarily unidirectional). Long p... » read more

Case Studies In Double-Patterning Debug

Double patterning (DP) impacts just about every part of the design and manufacturing flows. However, the kinds of issues you encounter, the way they manifest themselves, and the ideal way to address them may be very different in different parts of these flows. I feel like I have spent a lot of time the last six months or so working with place and route (P&R) and chip finishing engineers on DP i... » read more

Are Three Eyes Better Than Two?

It is clear that having two eyes is better than having just one. Not only is depth perception much better, but we get to enjoy 3D movies because of it. There is also some sense of security in knowing that if something terrible happened to one eye, you always have a backup. Have you ever wondered if these sorts of advantages are extendable? You’ve probably heard the phrase about someone ha... » read more

Balancing On The Color Density Tightrope

Balancing on wobbly tightropes is something that chip designers get pretty good at. For instance, there is a fine balance between optimizing performance and minimizing leakage in a design layout. Dealing with the new requirements that multi-patterning (MP) introduces into a design flow creates many new tightropes to walk. I tiptoed out on one of the rarely talked about ones in my last article... » read more

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