Software Becomes The Main Differentiating Factor

Lithography limitations will force restrictive design rules, which make software the defining factor for everything from better power utilization to different functionality.

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By Ed Sperling

Software has always been critical in determining what makes one chip different from another, but for the next couple of process nodes it will take on new significance. Rather than just defining function, it also will be one of the key determinants in performance and function.

Behind this change is a bottleneck in lithography, which generally is not something most design engineers even consider. Design for manufacturing tools are generally as close as they come to the manufacturing side, and for many of them, that’s as close as they ever want to get.

All of that will change at 32nm and 22nm, however. With extreme ultraviolet lithography still not ready for prime time—it most likely won’t be ready until at least 15nm, or maybe beyond—double patterning has emerged as the best alternative for building complex SoCs.

The current lithography technology uses a wavelength of 193nm, compared with EUV, which is 13.5nm. The last time the industry encountered a lithography problem of this magnitude was heading down to the 1 micron process node, when many scientists predicted the end of Moore’s Law.

That never happened, of course. The semiconductor industry consistently has managed to skirt problems by using a variety of tricks. The likely workaround over the next couple nodes will include double patterning of some sort, coupled with some highly restrictive design rules.

Those design rules are a formula for creating chips that can be manufactured with reasonable yield and a minimum of re-spins. But they also make one vendor’s chip look very much like another’s, leaving software as the primary—and in some cases the only—differentiator. And that differentiation applies to how much power a chip consumes, how fast it runs, as well as the look and feel of a device.

“As we get into 32nm, there is no other option but double patterning with immersion,” said Joanne Itow, managing director for manufacturing at Semico Research. “Very restrictive rules are the only way to get to manufacturing. At 22nm, there is not much more we can do without either EUV or e-beam (electron beam) technology.”

That helps explain why Intel bought Wind River last week. If the application software can be written for a thin executable layer, then its performance and energy consumption can be tailored to one or more specifically sized cores.

Texas Instruments has been working on the same approach. Srik Gurrapu, TI’s C5000 product marketing manager, said TI’s open multimedia application platform (OMAP) uses real-time operating systems from Wind River to cut power and improve performance.

“We don’t want a single operating system,” Gurrapu said. “Medical, industrial and commercial products all need different operating systems. There are different ways of achieving power savings.”

How that relationship will change with Intel’s acquisition is uncertain. But the trend toward using software to differentiate power consumption and performance already is well established for some specialized processors and microcontrollers.

Chartered Semiconductor, part of the Common Platform triumvirate with IBM and Samsung, has been working much more closely with ARM in recent months. The reason, once again, is the lithography bottleneck.

“Intel is buying its way into solutions, but for the foundry model things are still disaggregated,” said Walter Ng, vice president of design enablement alliances at Chartered. “But down the road, we’ll be sitting at the same table with ARM as an IP provider, an EDA provider and a software provider.”

Ng called it a “natural progression” of the relationship the Common Platform has established with ARM and other software developers. The Common Platform companies have their ecosystem, and ARM has its own. Ng expects the two to begin merging at future process nodes.

“Everyone says there is a chasm between design and manufacturing, but with ARM included there is no chasm. Design expertise, process and manufacturing are all there. Libraries have gone through two to three architectural reviews. The architecture that ARM is implementing to is beneficial to the process,” he said.

TSMC has been working more closely with its software and IP partners, as well. The company has been imposing restrictive design rules since 55nm, according to Itow.

That makes software all the more interesting for the next few years. So how well can you program in C?