Moore’s Law Revisited

By Ed Sperling
The push to 20nm and beyond is creating some interesting gyrations in the EDA industry. While tools vendors continue to work on tools for the latest process nodes, they’re also taking some significant sidesteps.

The first to publicly recognize a shift is under way was Cadence, which last year issued its EDA 360 manifesto. The strategy is to continue investing in existing tool lines while also building an IP integration methodology and a software-down rather than hardware-up approach. With fewer companies able to stay on the Moore’s Law road map, Cadence was the first to offer up its alternative plans.

Over the past week, both Mentor and Synopsys have started unrolling their own diverse strategies. And while none of these companies is willing to give up the cash cows that have sustained their growth—modeling, simulation, synthesis, layout, and verification—there are some interesting new additions to the mix.

Mentor looks up and down
Mentor Graphics is among the most diversified of the three big vendors already, but in its core tools area it has been steadily focused on delivering Moore’s Law in 2D. This week the company began acknowledging that 2D design was running out of steam for an increasing number of companies. While memory and processor makers probably will continue push the limits down to single-digit nanometer designs, even the most advanced SoC developers will start seeing diminishing returns by 20nm, where double patterning will become a requirement.

Wally Rhines, Mentor’s chairman and CEO, said during a speech at Globalpress that the semiconductor industry has been riding the Moore’s Law wave of efficiency for 40 years. He said there are still major advances to be made, but not all of them will be from new process nodes.

“All the cost reduction was from shrinking feature sizes,” he said. “Moore’s Law will dissipate with time, but the learning curve will never dissipate. Shrinking features in 2D will not only be more difficult, but it will be more expensive.”

In other words, the return on investment goes down with each node. At 20nm, double patterning will be required, which will make the economic corollary to Moore’s Law difficult to maintain. “This is the first time a change in area will not provide a big cost reduction,” Rhines said.

Mentor has been rather quiet on 2.5D and 3D stacking until now, but this week it came out strongly in favor of the shift. In 2.5D, an interposer is used to connect various die together. In 3D, through-silicon vias will be used for the connections.
“The most promising solution is to grow in a third dimension,” Rhines said. He said that 3D ultimately will offer huge benefits, but added that “2.5D will last much longer than people expect.”

Mentor’s initial play for this market will be through its Tessent testing capabilities. Testing in 3D is extremely complicated because not all of the standard connections for testing are available in a stacked die. The company also will likely have to tweak its DFM tools, because a yield issue involving three die stacked together is three times as expensive as a single die failure. Many of the other tools sold by the company are expected to be tweaked to work with 3D stacks.

“Over the next two to three years you’ll start seeing products with interposers,” Rhines said, adding that by shortening and widening the channels there will be both significant performance increases and a major reduction in the power needed to drive signals. And as aside, he noted that the first TSV patent was filed by William Shockley in 1958.

Synopsys looks sideways
Synopsys president and CEO Aart de Geus believes there is plenty of life left in Moore’s Law—at least for its top customers. He said there is work under way well beyond 16nm and that new transistor types such as FinFETS are being developed to work at those geometries. But he also acknowledged the growth of multichip stacks connected through an interposer.

Synopsys has been a bit more bullish publicly about 2.5D and 3D than Mentor, although not nearly as vocal as Cadence. But it has been much quieter about some of its work in adjacent markets. This week de Geus peeled back the covers on a cloud-based approach for the company’s tools, which he said can be billed by the hour or even portions of an hour for intensive debugging. That should quell some of the concerns for buying tools at advanced nodes because the tools themselves were underutilized much of the year.

Cloud-based approaches are interesting because capacity can be turned on and off. Synopsys has a license from Amazon, which is one of the more recent pioneers of this strategy. The cloud approach basically is a sophisticated repackaging of the old mainframe time-sharing. But time-sharing involved limited resources and rather rigid scheduling, whereas the modern cloud approach is much more flexible because the cost of compute resources has declined in accordance to Moore’s Law. The big cost now is housing the servers and providing the power to run them and cool them, which is why they have to be fully utilized to be cost-effective. Most companies cannot utilize them fully, which makes the cloud model increasingly attractive.

“We can sell simulation by the hour or even lower,” said de Geus at the Synopsys User Group meeting this week.

One of the big problems with acceptance of cloud-based strategies so far has been that sensitive company data has to be moved outside of the company for testing. Synopsys insists that will no longer be a problem. “The information is very secure,” de Geus said. “Cloud providers are providing military security, which the company’s can’t even do themselves. Companies have not had the right legal framework to deal with this in the past. But that’s changing at a super rapid speed.”

Synopsys also is moving into a number of new adjacent markets such as optical. De Geus said the keys for successful adjacent markets are that they share the same technology or the same channel or the same customers. “If you don’t have a reasonable sense for these adjacencies then you increase your risk.” He joked that’s why Synopsys will never buy a shoe company.