Handel Jones, founder and CEO of International Business Strategies, Inc. (IBS), agrees. FDSOI has advantages over bulk CMOS, because it offers “low power consumption compared to bulk CMOS at 28 nm and 20 nm – roughly by 30 percent, while providing lower cost per transistor by 5 percent at 28 nm and 25 percent at 20 nm,” Jones explained. Further, he added, FDSOI’s “design flow is similar to bulk CMOS.” And “body biasing gives additional flexibility in design.”
Where things get tricky, though, is that FDSOI at 20nm (which ST calls
“14-nm FDSOI”) may have a relatively limited window to prove its worth.
Jones pegged that opportunity at 12 to 24 months.
The reason for
this one-to-two year window is because industry observers believe that
20-nm bulk CMOS – currently pursued by foundries – is unlikely to ramp
rapidly into high-volume production because of parametric yield
challenges. More specifically, Jones called control of leakage “very
difficult at 20 nm,” because of problems with doping uniformity and line
Similarly, IBS predicts that 16/14-nm FinFETs are
not likely to be in high-volume production until Q4/2016 or Q1/2017.
“The reason is due to challenges in getting lower cost per transistor
compared to 28-nm bulk CMOS,” said Jones. That again will create a fresh
opportunity for the FDSOI at 16/14-nm node, in his opinion.
Although many agree that migration to FinFETs is inevitable, they also point out that foundry challenges should not be ignored. Speaking of FinFET, Jones noted, “Multiple iterations of chip designs are required to get lower cost per transistor compared to 28 nm and potentially 20 nm.”
So, what makes a credible ecosystem with FDSOI?
If, as suspected, ST has a volume customer for its FDSOI process, the need for a second-source foundry becomes paramount. And that’s where GlobalFoundries comes in. A GlobalFoundries’ spokesman, when recently reached, reiterated, “We are the manufacturing partner for ST’s FDSOI technology.”
Asked about the transition to FDSOI, the GlobalFoundries’ spokesman said, “There is certainly work to be done with any new process technology, but FDSOI is a planar process using the same front end and back end as our 28-nm-SLP process. It also allows for IP reuse from bulk technology, which makes for a simpler transition.”
The devil is always in the details, however. ST’s ecosystem, according to IBS’ Jones, needs “design flows, support of body biasing and other” elements necessary to optimize the value of the technology.
Wayne Dai, CEO of VeriSilicon, acknowledged, “As a leading IC design foundry, for the past few years, we’ve been tracking technology development of FDSOI.” He told EE Times
, “VeriSilicon is designing semiconductor IPs for the technology, in particular, using body biasing techniques and providing turnkey service to the customers of ours who indicated interest on FDSOI.”
Dai was an early believer in the FDSOI technology. He said, “As planar bulk CMOS is approaching to a limit and 3D bulk CMOS (FinFETs) is not yet commercially available, 28-nm FDSOI provides an alternative to planar bulk CMOS beyond 28 nm.” In his opinion, FDSOI at 20 nm or beyond will help “build SOI substrate infrastructure for 3D FDSOI (FinFET on SOI), which will eventually become an alternative to 3D Bulk CMOS.
Hutcheson, however, cautioned. “FDSOI is more like dual-overhead cams … it’s a nice feature, but what the customer really cares about is how the finished design performs.”
For now, ST is keeping mum on the timing for launch of its customers’ FDSOI-based chips.
VLSI Research’s Hutcheson believes that “most foundries consider FDSOI to be too costly and problematic. GlobalFoundries is the one exception.”
It’s unclear if the industry landscape remains equally dubious.
ST, for one, clearly anticipates a growing demand for FDSOI, as Jean-Marc Chery, chief manufacturing and technology officer at ST, indicated in a recent interview with EE Times
. The company is considering plans to offer its FDSOI process to second-tier foundries United Microelectronics Corp. and SMIC.
IBM is also eager to license FDSOI technology far and wide. Mark McLeod, program manager, technology alliances and licensing at IBM, explained, “IBM has the licensing rights to ST's 28-nm FDSOI and the follow-on nodes that we are developing together.”