SAN FRANCISCO — In a move that may extend 28nm mode and attract low-power, low-margin wearables and smartphone markets, European semiconductor manufacturer STMicroelectronics is partnering with Samsung on the 28nm FD-SOI (fully depleted silicon on insulator) process.
Under the agreement announced Wednesday (May 14), Samsung will license from ST 28nm FD-SOI design platform, thus making its foundry services effectively accessible to the broader semiconductor industry. Moreover, the two fabs have agreed to maintain compatible design processes.
"It's not been a very well kept secret," Dean Freeman, Gartner's research vice president, told EE Times. ST even mentioned an agreement was signed in its earnings call in April. ST's investor day is tomorrow in New York.
Samsung brings reliable production capacity to 28nm FD-SOI, which the companies hope will encourage designers to adopt the process. While ST is already qualified for volume production at its Crolles facility, they needed more production volume. "ST couldn't support it [28nm FD-SOI] so they needed a partner," said Len Jelinek, IHS's research director for semiconductor manufacturing, in an interview with EE Times. "Choosing Samsung was a logical move."
Also part of the enticement to designers wanting to dive into FD-SOI is that staying with 28nm mode means, in theory, no new non-recurring engineering costs. In other words, the 28nm masked set transfers to the 28nm FD-SOI and no $50-million-plus redesign needs to happen as you would see with a jump to new process node.
The partnership, dubbed an "extended strategic collaboration," takes advantage of Samsung's experience with 28nm bulk CMOS. While Samsung aims for full qualification on the FD-SOI process in early 2015, the process design kit (PDK) is available now to get customers designing. The design platform Samsung is licensing includes the PDK, foundation libraries, advanced IP, and design flow. IP offered will be standard cells, memory, analog, advanced IP, among others.
Having the PDK immediately available for designers to start using while Samsung qualifies its process is "very opportunistic," said IHS' Jelinek.
"I suspect they are going for the burgeoning cheap smartphone market, especially in China and Taiwan" where the cheap smartphone are about to explode, said Jelinek. In a year while Samsung gets ready, its customers will also be ready to start production. "I found it to be very interesting, timely, and compelling announcement."
Smartphone chip manufacturers in China are still at 40nm process and weren't planning on going to 28nm because of cost, said Jelinek. The agreement makes it less of a risk for designers wanting to try the technology,
"We heard from customers asking for FD-SOI at 28nm," said Kelvin Low, senior director of marketing, Samsung Foundry, said on a call with EE Times.
Jean-Marc Chery, ST's chief operating officer, also said on a call with EE Times, that some of the naysaying had to do with the capacity not being there. Now that Samsung is on board with ST, that worry should go away, he implied.
Faster, cooler, simpler is ST/Samsung pitch. FD-SOI benefits over bulk CMOS are that transistors are 30% faster and end-user devices run cooler because power leakage is lower in FD-SOI. The manufacturing process is simpler, they claim, because they are using existing fab infrastructure and designers of devices don't have to reengineer their 28nm designs.
IHS' Jelinek concurs. "IBM also had the FD-SOI process [working with Global Foundaries] but didn't make it accessible [to a broader set of customers]." This agreement makes the process more accessible, he said.
Jury still out
But don't expect a stampede toward 28nm FD-SOI. "If SOI is all that it's cracked up to be, why isn't Intel and others on it? I acknowledge its technical possibilities, but will we see a stampede [toward 28nm FD-SOI]?" Gartner's Freeman, who admits being on the fence about FD-SOI for a long time, "We haven't seen it yet and probably won't unless ST comes up with device that blows everyone away."
28-nm FD-SOI is supposed to afford a 30% faster performance. "But that's at maximum frequency," said Freeman, "and no device operates at maximum frequency all the time. It's more likely 15 to 20%" performance increase."
"I would characterize it as an interim step for Samsung until they get to 14nm," Kevin Krewell of Tirias Research told EE Times. "FD-SOI offers power benefits but you don't get the strength." He explained that the process does work well for wearables where the idle power is most important. FD-SOI gives just enough performance to handle a wearable's work and small display but it reduces the power to extend the battery life that is more important in wearables, which spend most of their lives in sleep mode. Having an efficient sleep mode that doesn't leak power is ideal. FD-SOI, with its lower voltages than bulk CMOS, could achieve that.
"28nm hits a sweet spot," as process and wafer costs go up, Krewell said. "Especially in embedded and wearables, expect to see 28nm around for a long time."
The team estimates the next next formal announcement will in early 2015 when Samsung becomes qualified on the process.