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Self-Aligned Double Patterning—Part Deux

In my last article, I introduced you to the basic Self-Aligned Double-Patterning (SADP) process that is one of the potential candidate techniques for processing metal layers at 10nm and below, but let’s have a quick recap. SADP uses a deposition and etch step process to create spacers surrounding a patterned shape (Figure 1). As you can see, there are two masking steps—the first mask is cal... » read more



Self-Aligned Double Patterning, Part One

I’m sure most of you have seen a Rorschach test ink blot (Figure 1). Psychiatrists ask the subjects to tell them what they “see” in the ink blot. The answers are used to characterize the respondent’s personality and emotional functioning. I am never sure if I would feel more uncertain being the psychiatrist asking the question, or the subject trying to decide what to say, given there ar... » read more



When Order Matters

Do you brush your teeth before dinner? Put on your shoes before going to bed? Iron your clothes before you wash them? Okay, forget that last one. No one irons clothes anymore…do they? Anyway, my point is, if you want to achieve the best results from a process, order can be really important. And so it is with double patterning (DP) error debugging. As I’ve discussed, there are many types ... » read more



The Trouble With Triples—Part 2

In my last blog, we started to look at some of the challenges of triple patterning (TP) compared to double patterning (DP). In particular, we looked at the algorithmic complexity of determining if a valid coloring solution exists, and if so, producing a three-mask decomposition. This time, let’s look into the challenges of what to do if a layout is not legally decomposable into three colors. ... » read more



The Trouble With Triples—Part 1

If you’re a true geek like me, you may remember the Star Trek episode “The Trouble with Tribbles,” about the cute furry little aliens that purr when you pet them. They seemed so nice and friendly on the surface, but in the end, they became an exponentially growing mass of ravenous monsters that almost broke down the ship and consumed the storehouse of grain that was meant to provide human... » read more



You Ain’t Seen Nothing Yet

I’ve been talking about double patterning for a long time now in this series of blogs. I thought it might be good to start looking ahead at what is next for multi-patterning (Don’t Panic!). As you may have been hearing or reading, it doesn’t look like EUV lithography is going to be ready for 10nm, and may not even make it for 7nm. This means that alternative methods of extending the exist... » read more



You Can’t Get There From Here

By David Abercrombie In my last article, I reviewed the aspects of cell design that are affected by double patterning (DP). This time, I’ll discuss how automatic routing is affected by DP. Let’s begin by looking at the interaction between decisions made at the cell design level and decisions made at the routing level. One key routing decision is whether or not you will allow cell-to-cel... » read more



Between A Rock And A Hard Place

By David Abercrombie My previous articles included a lot of discussion about correcting error violations in double patterning (DP). This time let’s take a step back up the design flow. DP requires a design team to make some important decisions about standard cell design methodologies, or risk running into serious placement issues down the line. Understanding why this is so, and what your opt... » read more



Chasing Rabbits

“Now, here, you see, it takes all the running you can do, to keep in the same place. If you want to get somewhere else, you must run at least twice as fast as that!” —Lewis Carroll, Through the Looking Glass By David Abercrombie As I discussed in my previous article, the use of stitching can greatly reduce the number of double patterning (DP) decomposition violations that a designer ... » read more



Hospital Privileges

By David Abercrombie In our double patterning (DP) conversations so far, we’ve discussed what it means to decompose a single layer into two masks, and identified typical configurations of polygons that can cause DP violations. We specifically discussed the most common odd cycle violations, and how to fix them by increasing the spaces between polygons. The reality, though, is that no matter h... » read more



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