By Ronald M. Martino, Vice President, i.MX Applications Processor and Advanced Technology Adoption, NXP Semiconductors
At NXP, we’re very excited about the prospects for our new i.MX 7 and 8 series of applications processors, which we’re manufacturing on 28nm FD-SOI.
As noted in part 1 of this article series, the new i.MX 7 series, which leverages the 32-bit ARM v7-A core, is targeting the general embedded, e-reader, medical, wearable and IoT markets, where power efficiency is paramount. The i.MX 8 series leverages the 64-bit ARM v8-A series, targeting automotive applications, especially driver information systems, and well as high-performance general embedded and advanced graphics applications.
Choosing an FD-SOI solution gave our designers some specific tools that helped them to more easily and robustly deliver the features our customers are looking for. Here in part 2, we’ll look a little more deeply into the markets each of these chip families is targeting, and the role FD-SOI plays in helping us meet our specs.
Announced last June, the first members of our new 7 series — the i.MX 7Solo and i.MX 7Dual product families — will be hitting the market shortly. We’ve been shipping samples since last year, and the response has been tremendous. (You can read about the i.MX 7 IoT ecosystem we’re helping create for our customers here and support for wearable markets here.)
Our i.MX 7 customers are building products for power- and cost-sensitive markets. That of course includes a vast array of innovative IoT solutions and wearables, but also solutions for other parts of the embedded market like handheld point-of-sale (POS) and medical devices, smart home controls and industrial products. The i.MX 7 series also continues NXP’s industry leading support for the e-reader market via integration of an advanced, fourth-generation EPD controller.
For all these markets, excellent performance is very important, but both dynamic and static power figures are really key. When you’re creating a system with power efficient processing and low-power deep sleep modes, you enable a new tier of performance-on-demand, battery-operated devices that are lighter and cheaper, and in a virtuous cycle require smaller batteries.
The next members of the NXP i.MX 7 series combine ultra-low power (dynamically leveraging the reverse back biasing you can do with FD-SOI) and performance-on-demand architecture (boosted when needed with FD-SOI’s forward back-biasing). It’s the industry’s first general purpose microprocessor family to incorporate both the ARM® Cortex®-A7 and the ARM Cortex-M4 cores (customers can choose between single or dual A7 cores). These technologies, together with our new companion PF3000 power management IC, unleash the potential for dramatically innovative, secure and power efficient end-products for wearable computing and IoT applications.
The initial offering of i.MX 7 was designed (on 28nm bulk) with Cortex-A7 cores operating up to 1 GHz, while the Cortex-M4 core operates at up to 200 MHz. The Cortex-A7 and Cortex-M4 achieve processor core efficiency levels of 100 microWatts (μW) /MHz and 70 μW /MHz respectively.
A Low Power State Retention (LPSR), battery-saving mode can be improved by FD-SOI and consumes only 250 μW, representing a 3x improvement over our previous generation (on 40nm bulk). That’s almost 50% better than our competitors. Plus it minimizes wake up times without requiring Linux reboot, while supporting DDR self-refresh mode, GPIO wakeup, and memory state retention.
The next members of the i.MX 7 series, with FD-SOI dynamic back-biasing, enable different blocks to be reverse or forward back-biased on the fly to attain always-optimal power savings or performance. Additional power optimization features are enabled to achieve leadership power efficiency. We’ve optimized FD-SOI dynamic back-biasing to enable performance-on-demand architecture through which the i.MX 7 series meets the bursty, high-performance needs (this is when forward back-biasing kicks in) of running Linux, graphical user interfaces, high-security technologies like Elliptic Curve Cryptography, as well as wireless stacks or other high-bandwidth data transfers with one or multiple Cortex-A7 cores.
When high levels of processing are not needed, low-power modes kick in with reverse back biasing of the critical subsystems, and the ongoing, real-time work is carried on by the smaller, lower powered Cortex-M4.
All things considered, it’s perhaps no surprise that we expect i.MX 7 series solutions for cost-sensitive markets to be a key driver of our long-term i.MX portfolio expansion.
Our new i.MX 8 series portfolio, based on 28nm FD-SOI process technology, targets highly-advanced driver information systems and other multi-media intensive embedded applications. It incorporates those same key attributes as the i.MX 7, but extends them into realms the industry has never experienced. We believe the i.MX 8 series is poised to revolutionize interactivity in multimedia and display applications across all kinds of industries.
i.MX 8 incorporates innovations in the processor — complex graphics, vision, virtualization and safety to help revolutionize interactivity for a wide range of uses in many, many markets. The capabilities of this family is broad, but one of the places it’s going to be the biggest game-changer is in what is becoming the e-cockpit of your car.
For almost two decades, SOI has shone in the embedded processing world. In addition, NXP counts every major automotive maker in the world amongst its customers for our devices. Entering the new e-cockpit frontier, 28nm FD-SOI is the logical choice in making the i.MX 8 series meet and exceed the stringent requirements of top automotive OEMs for years to come.
The i.MX 8 series leverages ARM’s V8-A 64-bit architecture in a 10+ core complex that includes blocks of Cortex-A72s and Cortex-A53s. All the FD-SOI advantages discussed above for the i.MX 7 are also being brought to bear here (the power envelope for automotive designers being extremely strict). But in the hot and electrically noisy automotive environment, FD-SOI also plays an important role in ensuring robust operation.
The way we see it, your car’s multimedia centric e-cockpit will revolve around the i.MX 8, a single chip that drives all displays from infotainment to heads-up-displays (HUD) to instrument clusters. It’s optimized for the intelligent transfer of data and information management from multiple subsystems within the IC – as opposed to only delivering raw performance through one or two processing blocks.
For drivers and passengers alike, we’re looking at a very different world: one that includes the spread of advanced heads-up displays, intuitive gesture control, natural speech recognition, augmented reality, enhanced convenience and device connectivity. (I wrote a blog exploring the possibilities last fall – you can read it here.)
And of course, it will be secure from hackers, and fail-safe for critical systems.
From our customers’ standpoint, they can design a single hardware platform and scale it across multiple market segments with the unique approach to pin and software compatibility within the i.MX product families.
The i.MX family has been leveraged in over 35 million vehicles since it was first launched in vehicles in 2010. So with all these new features, and low-power and robust performance, we see a very bright future for FD-SOI and the i.MX 8 in automotive. It’s going to be a great ride.
By Ronald M. Martino, Vice President, i.MX Applications Processor and Advanced Technology Adoption, NXP Semiconductors
The latest generations of power efficient and full-featured applications processors in NXP’s very successful and broadly deployed i.MX platform are being manufactured on 28nm FD-SOI. The new i.MX 7 series leverages the 32-bit ARM v7-A core, targeting the general embedded, e-reader, medical, wearable and IoT markets, where power efficiency is paramount. The i.MX 8 series leverages the 64-bit ARM v8-A series, targeting automotive applications, especially driver information systems, as well as high-performance general embedded and advanced graphics applications.
Over 200 million i.MX SOCs have been shipped over six product generations since the i.MX line was first launched (by Freescale) in 2001. They’re in over 35 million vehicles today, are leaders in e-readers and pervasive in the general embedded space. But the landscape for the markets targeted by the i.MX 7 and i.MX 8 product lines are changing radically. While performance needs to be high, the real name of the game is power efficiency.
The bottom line in chip manufacturing is always cost. A move from 28nm HKMG to 14nm FinFET would entail up to a 50% cost increase. Would it be worth it? While FinFETs do boast impressive power-performance figures, for applications processors targeting IoT, embedded and automotive, we need to look beyond those figures, taking into account:
In fact, both NXP and the former Freescale have extremely deep SOI expertise. Freescale developed over 20 processors based on partially-depleted SOI over the last decade; and NXP, having pioneered SOI technology for high-voltage applications, has dozens of SOI-based product lines. So we all understand how SOI can help us strategically leverage power and performance. For us, FD-SOI is just the latest SOI technology, this time with a design flow almost identical to bulk, but on ultra-thin SOI wafers and some important additional perks like back-biasing.
When all the factors we care about for the new i.MX processor families are tallied up, FD-SOI comes out a clear winner for i.MX SOCs.
For our designers, here’s why FD-SOI is the right solution to the engineering challenges they faced in meeting evolving market needs.
In terms of power, you can lower the supply voltage (Vdd) – so you’re pulling less power from your energy source – and still get excellent performance. Add to that the dynamic back-biasing techniques (forward back-bias improves performance, while reverse back-bias reduces leakage) available with FD-SOI (but not with FinFETs), you get a very large dynamic operating range.
By dramatically reducing leakage, reverse back-biasing (RBB) gives you good power-performance at very low voltages and a wide range of temperatures. This is particularly important for IoT products, which will spend most of their time in very low-power standby mode followed by short bursts of performance-intense activity. We can meet the requirements for those high-performance instances with forward back-biasing (FBB) techniques. And because we can apply back-biasing dynamically, we can specify it to meet changing workload requirements on the fly. [Editor’s note: click here and here for helpful ASN articles with descriptions and discussions of back-biasing, which is also sometimes called body-biasing.]
Devices for IoT also have major analog and RF elements, which do not scale nearly so well as the digital parts of the chip. Furthermore analog and RF elements are very sensitive to voltage variations. It is important that the RF and analog blocks of the chip are not affected by the digital parts of a chip, which undergo strong, sudden signal switching. The major concerns for our analog/RF designers include gain, matching, variability, noise, power dissipation, and resistance. Traditionally they’ve used specialized techniques, but FD-SOI makes their job much easier and results in superior analog performance.
In terms of RF, FD-SOI greatly simplifies the integration of RF blocks for WiFi, Bluetooth or Zigbee, for example, into an SOC.
Soft error rates (SER)* are another important consideration, especially as the size and density of SOC memory arrays keep increasing. Bulk technology gets worse SER results with each technology node, while FD-SOI provides ever better SER reliability with each geometry shrink. In fact, 28nm FD-SOI provides 10 to 100 times better immunity to soft-errors than its bulk counterpart.
Our process development strategy has always been to leverage foundry standard technology and adapt it for our targeted applications, with a focus on differentiating technologies for performance and features. We typically reuse about 80% of our technology platform, and own our intellectual property (IP). Looking at the ease of porting existing platform technology and IP, and analyzing die size vs. die cost, again, FD-SOI came out the clear choice.
In terms of manufacturing, FD-SOI is a lower-risk solution. Integration is simpler, and turnaround time (TAT) is much faster. 28nm FD-SOI is a planar technology, so it’s lower complexity and extends our 28nm installed expertise base. Throughout the design cycle, we’ve worked closely with our foundry partner, Samsung. They provided outstanding support, and very quickly reached excellent yield levels, which is of course paramount for the rapid ramp we anticipate on these products.
In the second part of this article, we’ll take a look at the new i.MX product lines, and why FD-SOI is helping us make those game-changing plays for specific markets.
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* Soft errors occur when alpha or neutron particles hit memory cells and change their state, giving an incorrect read. These particles can either come from cosmic rays, or when radioactive atoms are released into the chips as materials decay.
ASN spoke with Kelvin Low, senior director of marketing for Samsung Foundry and Axel Fischer, director of Samsung System LSI business in Europe about the company’s FD-SOI offering. Here in part 1, we’ll talk about technology readiness. In parts 2 and 3, we’ll talk about design and the ecosystem.
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ASN: Where does Samsung stand in terms of rolling out your 28nm FD-SOI offer?
Kelvin Low: We have completed key milestones. Wafer level qualification was completed in September 2014, and then product level qualification in March 2015. So, the good news is the technology is fully qualified now.
What we have additionally in terms of overall technology readiness is production PDKs available right now. We have run a couple of MPWs already, and we’re scheduling more for next year. Silicon is really running in our fab. I think many may not have grasped that fact. Silicon is running, and we are running production for ST as one of our lead customers.
Axel Fischer: We already have a long relationship with ST – since 32 and 28nm HKMG bulk. We had a press release where we stated that more than a dozen projects had been taped out. EETimes published an article at the time. Adding 28 FD-SOI was a natural extension of an existing relationship
KL: That’s right –This is not a new customer scenario – it’s an existing customer, but an expansion of technology. And, in this case, it’s also a collaboration technology and IP solutions.
We are ST Micro’s primary manufacturing partner; this is one reason that it’s mutually beneficial for both of us. Crolles is not aiming for high volume. They prototype well. They do MPW and IP well, but they are not a high-volume fab. So, we complete the production rollout at Samsung Foundry.
ASN: Do you have other customers lined up?
KL: The short answer is yes. Beyond ST, Freescale can we talk about, since they have openly stated that they are using FD-SOI with us. Other customers, unfortunately, we just can’t say.But, they are in all the market segments (especially IoT) where the cost and ultra-low power combination is a very powerful one.
ASN: What about technology readiness and maturity?
KL: We have a couple of different 28 variants: the LPP, the LPH with more than a million wafers shipped. And because of that, our D0 – defect density – is at a very mature level. 28FD-SOI, sharing almost 75% of the process modules of 28 bulk, allows us to go to a very steep D0 reduction curve. We are essentially leveraging what we already know from the 28 bulk production experience. Defect density is essentially the inverse of yield. So, the lower the D0, the higher the yield.
This slide [[see above]] show the similarities between our FD-SOI and our 28 HKMG bulk. You can see how more than 75% of bulk modules are reused. The BEOL is identical, so its 100% reused. On the FEOL, some areas require some minor tuning and some minor modification, but anything that is specific to FD-SOI is less than 5% that we have to update from the fab perspective. All the equipment can be reused in the fab. There may be a couple of pieces related to the FD-SOI process that need to be introduced.Other than that, the equipment is being reused and can depreciated,.which is essential for any business. We leverage another lifetime for the tools.
ASN: When will we see the first high-volume FD-SOI chips? Next year?
KL: It depends on what market segment. Consumer, yes, I fully agree, they can ramp very fast. But other segments like infrastructure, networking or automotive, they’ll take a longer time to just qualify products.
AF: It’s not just us. If our customer needs to prove that the product is compliant with certain standards, you have to go through test labs and so on, this can be a very lengthy process. Product can actually be ready, and we’re all waiting to produce, but they’re still waiting for reports and the software that’s goes on top – this can be a very long cycle.
KL: We’re already starting to support the production ramp for ST. They’ll be on the market very soon.
[[Editor’s note: ST has announced three set-top box chips on 28nm FD-SOI– you can read about them here.]]
KL: Everyone’s waiting for ChipWorks or TechInsights to cut away an end-product device that has FD-SOI. It’s just a matter of time.
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A very successful two-day forum on FD-SOI and RF-SOI in Shanghai (September 2015) featured presentations from CEOs, CTOs and VPs at GF, ST, Leti, ARM, Verisilicon, Synapse Design, SITRI, Skyworks, Freescale, TowerJazz, Soitec, Qorvo and many more. Most of the presentations are now available on the SOI Consortium Website, and the rest are expected shortly, so keep checking back.
To download the “Design for FD-SOI” presentations, see the list here.
To download the “RF-SOI Workshop – Interconnected World” presentations, see the list here. (Presentations from all of the major SOI wafer suppliers are also available on this page.)
With much fanfare, GlobalFoundries has officially announced its 22nm FD-SOI offering. Dubbed “22FDX™”, GF says the platform delivers FinFET-like performance and energy-efficiency at a cost comparable to 28nm planar, targeting mainstream mobile, IoT, RF connectivity and networking markets.
Asked by EETimes why FD-SOI here and now, GF’s CEO Sanjay Jha responded, “The mass market is at 28nm/22nm. Really it is leading-edge pure digital that is the niche.” (Read Peter Clarke’s full piece here.)
And so a new paradigm is born.
With FinFETs relegated to the leading-edge-pure-digital niche, GF says FD-SOI provides the best path for cost-sensitive applications (which is everything else, right?!). Their pitch: 22FDX offers the industry’s lowest operating voltage (0.4 volt), enabling ultra-low dynamic power consumption, less thermal impact, and smaller end-product form-factors. Plus it delivers a 20 percent smaller die size and 10 percent fewer masks than 28nm, as well as nearly 50 percent fewer immersion lithography layers than foundry FinFET.
It’s been three years since ST announced (in June 2012) that GF would be providing high-volume sourcing for FD-SOI, but you never saw it on GF’s website — til now. As of 13 July 2015, it’s there in a big way. Today, you can finally go to the GF website and see the headline on the homepage, or find out all about the offer on dedicated tech solution pages (click here to check it out yourself).
“The 22FDX platform enables our customers to deliver differentiated products with the best balance of power, performance and cost,” said Jha, who was on hand for the big event in Dresden, Germany. “In an industry first, 22FDX provides real-time system software control of transistor characteristics: the system designer can dynamically balance power, performance, and leakage. Additionally, for RF and analog integration, the platform delivers best scaling combined with highest energy efficiency.”
And of course it’s good new for the folks at GF’s Fab 1 in Dresden, in the heart of Germany’s “Silicon Saxony” region. GF’s invested another $250 million for technology development and initial 22FDX capacity there (that’s on top of the >$5 billion they’ve invested there since 2009). Further investments to support additional customer demand are planned, plus partnering with R&D and industry leaders to grow a robust ecosystem and to enable faster time-to-market as well as a comprehensive roadmap for its 22FDX offering.
If you read the ASN coverage of the FD-SOI Workshop during LetiDays a few weeks ago, you saw that GF’s 22nm FD-SOI has a 14nm front end and 28nm back end (read it here if you missed it before). At LetiDays, they also talked about body-bias “generators”. In the 22FDX press release they’re referring to it as “…software-control of transistor characteristics to achieve real time tradeoff between static power, dynamic power and performance.”
Here are the offerings in the 22FDX platform, each one targeting a specific area of applications.
22FD-ulp: ulp aka ultra-low power is an alternative to FinFET for the mainstream and low-cost smartphone market. With body-biasing, 22FD-ulp delivers greater than 70 percent power reduction compared to 0.9 volt 28nm HKMG, as well as performance equivalent to FinFET, says GF. For certain IoT and consumer applications, the platform can operate at 0.4 volt, delivering up to 90 percent power reduction compared to 28nm HKMG.
22FD-uhp: uhp aka ultra-high performance – this offers networking applications with analog integration the capabilities of FinFET while minimizing energy consumption. 22FD-uhp customizations include forward body-bias, application optimized metal stacks, and support for 0.95 volt overdrive.
22FD-ull: ull aka ultra-low leakage targets wearables and IoT. It delivers the same capabilities of 22FD-ulp, while reducing static leakage to as low as 1pA/μm (pA = picoamp = one million millionth (10-12) of an amp, folks). This combination of low active power, ultra-low leakage, and flexible body-biasing can enable a new class of battery-operated wearable devices with an order of magnitude power reduction.
22FD-rfa: rfa aka integrated RF and analog. It delivers 50 percent lower power at reduced system cost to meet the stringent requirements of high-volume RF applications such as LTE-A cellular transceivers, high order MIMO WiFi combo chips, and millimeter wave radar. The RF active device back-gate feature can reduce or eliminate complex compensation circuits in the primary RF signal path, allowing RF designers to extract more of the intrinsic device Ft performance.
GF says they’ve been working closely with key customers and ecosystem partners to enable optimized design methodology and a full suite of foundational and complex IP. Design starter kits and early versions of process design kits (PDKs) are available now with risk production starting in the second half of 2016.
ST: “GLOBALFOUNDRIES’ FDX platform, using an advanced FD-SOI transistor architecture developed through our long-standing research partnership, confirms and strengthens the momentum of this technology by expanding the ecosystem and assuring a source of high-volume supply,” said Jean-Marc Chery, chief operating officer of STMicroelectronics. “FD-SOI is an ideal process technology to meet the unique always-on, low-power requirements of IoT and other power-sensitive devices worldwide.”
Freescale: “Freescale’s® next-generation i.MX series of applications processors is leveraging the benefits of FD-SOI to achieve industry leading ultra-low power performance-on-demand solutions for automotive, industrial and consumer applications,” said Ron Martino, vice president of applications processors and advanced technology adoption for Freescale’s MCU group. “GLOBALFOUNDRIES’ 22FDX platform is a great addition to the industry which provides a high volume manufacturing extension of FD-SOI beyond 28nm by continuing to scale down for cost and extend capability for power-performance optimization.”
ARM: “The connected world of mobile and IoT devices depend on SoCs that are optimized for performance, power and cost,” said Will Abbey, general manager, physical design group, ARM. “We are collaborating closely with GLOBALFOUNDRIES to deliver the IP ecosystem needed for customers to benefit from the unique value of 22FDX technology.”
Verisilicon: “VeriSilicon has experience designing IoT SoCs in FD-SOI technology and we have demonstrated the benefits of FD-SOI in addressing ultra-low power and low energy applications,” said Wayne Dai, president and CEO of VeriSilicon Holdings Co. Ltd. “We look forward to collaborating with GLOBALFOUNDRIES on their 22FDX offering to deliver power, performance and cost optimized designs for smart phones, smart homes, and smart cars especially for the China market.”
Imagination: “Next-generation connected devices, in markets from wearables and IoT to mobile and consumer, require semiconductor solutions that provide an optimal balance of performance, power and cost,” said Tony King-Smith, EVP Marketing, Imagination Technologies. “The combination of GLOBALFOUNDRIES’ new 22FDX technology with Imagination’s broad portfolio of advanced IP – including PowerVR multimedia, MIPS CPUs and Ensigma communications – will enable more innovation by our mutual customers as they bring differentiated new products to the market.”
IBS: “FD-SOI technology can provide a multi-node, low-cost roadmap for wearable, consumer, multimedia, automotive, and other applications,” said Handel Jones, founder and CEO, IBS, Inc. “GLOBALFOUNDRIES’ 22FDX offering brings together the best in low-power FD-SOI technology in a low-cost platform that is expected to experience very strong demand.”
Leti: “FD-SOI can deliver significant improvements in performance and power savings, while minimizing adjustments to existing design-and-manufacturing methodologies,” said CEA-Leti CEO Marie-Noëlle Semeria. “Together, we can collectively deliver proven, well-understood design-and-manufacturing techniques for the successful production of GLOBALFOUNDRIES’ 22FDX for connected technologies.”
Soitec: “GLOBALFOUNDRIES’ announcement is a key milestone for enabling the next generation of low-power electronics,” said Paul Boudre, CEO of Soitec. “We are pleased to be GLOBALFOUNDRIES’ strategic partner. Our ultra-thin SOI substrate is ready for high-volume manufacturing of 22FDX technology.”
Choice is a beautiful thing, don’t you agree?
Freescale is designing its next generation microprocessor, the iMX7, on 28nm FD-SOI, EETimes has just revealed. This was in an article by Chief International Correspondent Junko Yoshida entitled Freescale, Cisco, Ciena Give Nod to FD-SOI (read it here). Freescale microcontroller SVP & GM Geoff Lees told EETimes the chip’s designed for “’secure’ IoT applications, including automotive (telematics, V2V, entry-level infotainment) and smart devices (healthcare, home appliances and factory automation)”. Samsung’s being tapped as the foundry. Cisco and Ciena are also using FD-SOI, the article stated.
A new book by two giants in SOI – Jerry Fossum of U. Florida/Gainesville and Vishal Trivedi of Freescale – delves into the Fundamentals of Ultra-Thin-Body MOSFETs and FinFETs. Available from Cambridge University Press in both hardcover and eBook formats (click here for more information), it covers theory, design and applications of FD-SOI MOSFETs and FinFETs (you can review the Table of Contents here). The book is billed as “a must-have resource” for professional engineers in the CMOS IC field who need to know about optimal nonclassical device design and integration.
ASN readers will remember that Dr. Fossum won the IEEE/EDS J. J. Ebers Award in 2004 for ‘outstanding contributions to the advancement of SOI CMOS devices and circuits through modeling’. They also may remember his concise, elegant argument back in 2007 (see article here) as to why SOI represents a pragmatic approach to FinFETs.
Are FinFETs better on SOI? In a series of papers, high-profile blogs and subsequent media coverage, Gold Standard Simulations (aka GSS) has indicated that, yes, FinFETs should indeed be better on SOI.
To those of us not deeply involved in the research world, much of this may seem to come out of nowhere. But there’s a lot of history here, and in this blog we’ll take a look at what it’s all about, and connect a few dots.
GSS is a recent spin-off of Scotland’s University of Glasgow – but there’s nothing new to the research community about these folks. The core GSS-U.Glasgow team has been presenting important papers on device modeling at IEDM (which is one of the most prestigious of our industry’s conferences) and elsewhere for many years.
At the risk of stating the obvious, accurate simulations are incredibly important. Technologists need to be able to predict what results they can expect from different possible transistor design options before selecting the most promising ones. Then they also need to provide reliable models to designers who will use them before committing chips to silicon. One of the biggest challenges is predicting variability, which as we all know is getting worse as transistors scale to ever-smaller dimensions.
At IEDM ’11 last December, GSS-U.Glasgow presented Statistical variability and reliability in nanoscale FinFETs. This covered “A comprehensive full-scale 3D simulation study of statistical variability and reliability in emerging, scaled FinFETs on SOI substrate with gate-lengths of 20nm, 14nm and 10nm and low channel doping…”. Essentially they concluded that scaling FinFETs on SOI should be no problem – and in fact the statistical variability of a 10nm FinFET on SOI would be about the same as the industry’s currently seeing in 45nm bulk CMOS.
That paper was based on work that the GSS-U.Glasgow team had done on two major European projects: the EU ENIAC MODERN project, and the EU FP7 TRAMS project. It’s perhaps worth looking a little more closely at what those projects are about – and who’s involved:
A few months later, when Chipworks published pictures of the (bulk silicon) Intel 22nm FinFETs, the folks at GSS started a series of blogs that caught the attention of major tech pubs such as EE Times, Electronics Weekly and EDN. For reference, here are the blogs and basically what they concluded:
Specifically, the July 27th blog indicated that if FinFETs are rectangular in shape, drive current would be 12-15% better. Would that be easier to do on an SOI wafer? Soitec has argued that their “fin-first” SOI-based approach to FinFET manufacturing will save both time & money while getting better results (see Soitec’s Wafer Roadmap for Fully Depleted Planar and 3D/FinFET in Semiconductor Manufacturing & Design).
The GSS blog also reminded readers that the company’s CEO and founder, Asen Asenov (an extremely heavy hitter who’s published over 550 papers), has hinted that “…SOI FinFETs with an almost ideal rectangular shape may be a better solution for future FinFET scaling”. GSS has noted previously that “FinFETs built on an SOI substrate could have significant advantages terms of simpler processing, better process control and reduced statistical variability”.
Fin shape aside, GSS said that by virtue of the layer of insulation, SOI would give another 5% boost to FinFET drive current. But perhaps more importantly, that layer of insulation in SOI-based FinFETs would deliver on average 2.5 times less leakage – which would translate into a doubling of battery-life for your cell phone.
IBM has now entered into an agreement with GSS et al on a project called StatDES, for Statistical Design and Verification of Analogue Systems – see last month’s IBM blog by IBM Research Scientist Dr. Sani Nassif, entitled “Fins on transistors change processor power and performance”.
Dr. Nassif writes, “IBM, University of Glasgow and the Scottish Funding Council are collaborating on a project to simulate 3D microprocessor transistors at a mere 14 nanometer scale (the virus that causes the common cold is more than twice as large at 32 nanometers). Using a silicon-on-insulator (SOI) substrate, the FinFET (fin field-effect transistor) project, called StatDES, promises to keep improving microprocessor performance and energy conservation.”
The steering group also includes folks from ST, Freescale, Wolfson and Cadence, so one would guess we’ll be hearing more from this project – and others like it, to be sure – in the future, wouldn’t you think?