The Future of Very Large-Scale Integration (VLSI) Technology

The historical growth of IC computing power has profoundly changed the way we create, process, communicate, and store information. The engine of this phenomenal growth is the ability to shrink transistor dimensions every few years. This trend, known as Moore’s law, has continued for the past 50 years. The predicted demise of Moore’s law has been repeatedly proven wrong thanks to technological breakthroughs (e.g., optical resolution enhancement techniques, high-k metal gates, multi-gate transistors, fully depleted ultra-thin body technology, and 3-D wafer stacking). However, it is projected that in one or two decades, transistor dimensions will reach a point where it will become uneconomical to shrink them any further, which will eventually result in the end of the CMOS scaling roadmap. This essay discusses the potential and limitations of several post-CMOS candidates currently being pursued by the device community.

Steep transistors: The ability to scale a transistor’s supply voltage is determined by the minimum voltage required to switch the device between an on- and an off-state. The sub-threshold slope (SS) is the measure used to indicate this property. For instance, a smaller SS means the transistor can be turned on using a smaller supply voltage while meeting the same off current. For MOSFETs, the SS has to be greater than ln(10) × kT/q where k is the Boltzmann constant, T is the absolute temperature, and q is the electron charge. This fundamental constraint arises from the thermionic nature of the MOSFET conduction mechanism and leads to a fundamental power/performance tradeoff, which could be overcome if SS values significantly lower than the theoretical 60-mV/decade limit could be achieved. Many device types have been proposed that could produce steep SS values, including tunneling field-effect transistors (TFETs), nanoelectromechanical system (NEMS) devices, ferroelectric-gate FETs, and impact ionization MOSFETs. Several recent papers have reported experimental observation of SS values in TFETs as low as 40 mV/decade at room temperature. These so-called “steep” devices’ main limitations are their low mobility, asymmetric drive current, bias dependent SS, and larger statistical variations in comparison to traditional MOSFETs.

Spin devices: Spintronics is a technology that utilizes nano magnets’ spin direction as the state variable. Spintronics has unique properties over CMOS, including nonvolatility, lower device count, and the potential for non-Boolean computing architectures. Spintronics devices’ nonvolatility enables instant processor wake-up and power-down that could dramatically reduce the static power consumption. Furthermore, it can enable novel processor-in-memory or logic-in-memory architectures that are not possible with silicon technology. Although in its infancy, research in spintronics has been gaining momentum over the past decade, as these devices could potentially overcome the power bottleneck of CMOS scaling by offering a completely new computing paradigm. In recent years, progress has been made toward demonstration of various post-CMOS spintronic devices including all-spin logic, spin wave devices, domain wall magnets for logic applications, and spin transfer torque magnetoresistive RAM (STT-MRAM) and spin-Hall torque (SHT) MRAM for memory applications. However, for spintronics technology to become a viable post-CMOS device platform, researchers must find ways to eliminate the transistors required to drive the clock and power supply signals. Otherwise, the performance will always be limited by CMOS technology. Other remaining challenges for spintronics devices include their relatively high active power, short interconnect distance, and complex fabrication process.

Flexible electronics: Distributed large area (cm2-to-m2) electronic systems based on flexible thin-film-transistor (TFT) technology are drawing much attention due to unique properties such as mechanical conformability, low temperature processability, large area coverage, and low fabrication costs. Various forms of flexible TFTs can either enable applications that were not achievable using traditional silicon based technology, or surpass them in terms of cost per area. Flexible electronics cannot match the performance of silicon-based ICs due to the low carrier mobility. Instead, this technology is meant to complement them by enabling distributed sensor systems over a large area with moderate performance (less than 1 MHz). Development of inkjet or roll-to-roll printing techniques for flexible TFTs is underway for low-cost manufacturing, making product-level implementations feasible. Despite these encouraging new developments, the low mobility and high sensitivity to processing parameters present major fabrication challenges for realizing flexible electronic systems.

CMOS scaling is coming to an end, but no single technology has emerged as a clear successor to silicon. The urgent need for post-CMOS alternatives will continue to drive high-risk, high-payoff research on novel device technologies. Replicating silicon’s success might sound like a pipe dream. But with the world’s best and brightest minds at work, we have reasons to be optimistic.

Author’s Note: I’d like to acknowledge the work of PhD students Ayan Paul and Jongyeon Kim.

DEFCON for Kids—Giving Kids the r00tz to Learn

This summer may be coming to an end, but it’s never too early to start thinking about next year. If you have children between the ages of 8 and 18, you may be planning another year of summer camp. And, if you’re an engineer whose children are interested in electronics, figuring out how things work, and learning how to break things, r00tz Asylum may be the perfect fit.

r00tz Asylum (formerly known as DEFCON Kids) is a part of the widely attended DEFCON hacker convention, which takes place annually in Las Vegas, NV. Parents who attend DEFCON can bring their children to r00tz Asylum sessions where they can learn about white-hat hacking.

Electrical engineer Joe Grand is a former member of the well-known hacker collective L0pht Heavy Industries and now runs product development firm Grand Idea Studio. Grand instructs hardware hacking classes for computer security researchers and has taken a subset of that work to share with r00tz Asylum kids.

“I enjoy teaching kids because of the direct connection you have with them,” Grand said. “When you talk to them normally and explain things in simple ways, they get it!” he added. “It’s fun to see their eyes light up.”

But is teaching kids hacking a good thing? “Naysayers don’t understand the hacking mindset, which is about free thinking, circumventing limitations, and creating elegant solutions to tricky problems” Grand said. “Teaching kids to hack gives them super powers—with guidance.”

r00tz Asylum agrees. According its website, “Hacking gives you super-human powers. You can travel time and space. It is your responsibility to use these powers for good and only good.”

Teaching kids about white-hat hacking helps them learn to solve problems, be aware of the law, and understand the consequences for breaking it. And that’s where instruction in a positive and supportive environment comes in.

“Technology isn’t going away. We’re only going to become more immersed in it,” Grand said. “Kids need to be exposed to new things. It’s important to give them an environment where it’s okay to break things, that it’s okay if things fail.” But he stressed that, “Kids need boundaries. It’s our responsibility to teach them right from wrong.”

In addition to various classes, r00tz Asylum attendees have access to a hangout space of sorts with a soldering station and other resources. Last year the space featured a MakerBot 3-D printer, this year an Eggbot open-source art robot was available.

I asked Grand if either of his children would be attending r00tz Asylum in the future. He said he recently watched DEFCON: The Documentary with his four year old. When they watched the part about DEFCON Kids, his son’s reaction was: “I want to go!”

For more information about r00tz Asylum visit www.r00tz.org

Laurent Haas Wins the CC Code Challenge (Week 11)

We have a winner of last week’s CC Weekly Code Challenge, sponsored by IAR Systems! We posted a code snippet with an error and challenged the engineering community to find the mistake!

Congratulations to Laurent Haas of Paris, France for winning the CC Weekly Code Challenge for Week 11! Laurent will receive CC T-shirt and The CC25 Anniversary Edition.

Laurent’s correct answer was randomly selected from the pool of responses that correctly identified an error in the code. Laurent answered:

Line 6: reverse must be initialized to 0 => int reverse = 0;

You can see the complete list of weekly winners and code challenges here.

What is the CC Weekly Code Challenge?
Each week, Circuit Cellar’s technical editors purposely insert an error in a snippet of code. It could be a semantic error, a syntax error, a design error, a spelling error, or another bug the editors slip in. You are challenged to find the error.Once the submission deadline passes, Circuit Cellar will randomly select one winner from the group of respondents who submit the correct answer.

Inspired? Want to try this week’s challenge? Get started!

Submission Deadline: The deadline for each week’s challenge is Sunday, 12 PM ESTRefer to the Rules, Terms & Conditions for information about eligibility and prizes.

Multiband 4G LTE-Only Modules

The TOBY-L1 series is u-blox’s latest line of ultra-compact long-term evolution (LTE) modules. The TOBY-L100 and its European version, the TOBY-L110, are suitable for tablets, mobile routers, set-top boxes, and high-speed machine-to-machine (M2M) applications (e.g., digital signage, mobile health, and security systems).

Compared with multi-mode modules, LTE-only modules offer cost advantages. Therefore, the TOBY-L1 works well in networks with advanced LTE deployment applications.

The LTE modules are available in two versions: the TOBY-L100 for the US (bands 4 and 13 for Verizon) and the TOBY-L110 for Europe (bands 3, 7, and 20 for EU operators). Contained in a compact 152-pin LGA module, the TOBY-L1 series is layout-compatible with u-blox’s SARA Global System for Mobile (GSM) and LISA Universal Mobile Telecommunications System/Code Division Multiple Access (UMTS/CDMA) module series to facilitate easy product migration and low-cost regional end-device adaptation.

The TOBY-L1 modules are based on u-blox’s LTE protocol stack. The modules support smooth migration between 2G, 3G, and 4G technologies and feature small packaging and comprehensive support tools. The TOBY-L1 LGA modules measure 2.8 mm × 24.8 mm × 35.6 mm, which enables them to easily mount on any application board.

The modules support USB 2.0 and firmware update over the air (FOTA) technology. The TOBY-L1 series delivers ultra-fast data rates and operates from –40°C to 85°C. USB drivers for Windows XP and 7 plus Radio Interface Layer (RIL) software for Android 4.0 and 4.2 are available free of charge.

Contact u-blox for pricing.

u-blox
www.u-blox.com

AAR Arduino Autonomous Mobile Robot

The AAR Arduino Robot is a small autonomous mobile robot designed for those new to robotics and for experienced Arduino designers. The robot is well suited for hobbyists and school projects. Designed in the Arduino open-source prototyping platform, the robot is easy to program and run.

The AAR, which is delivered fully assembled, comes with a comprehensive CD that includes all the software needed to write, compile, and upload programs to your robot. It also includes a firmware and hardware self test. For wireless control, the robot features optional Bluetooth technology and a 433-MHz RF.

The AAR robot’s features include an Atmel ATmega328P 8-bit AVR-RISC processor with a 16-MHz clock, Arduino open-source software, two independently controlled 3-VDC motors, an I2C bus, 14 digital I/Os on the processor, eight analog input lines, USB interface programming, an on-board odometer sensor on both wheels, a line tracker sensor, and an ISP connector for bootloader programming.

The AAR’s many example programs help you get your robot up and running. With many expansion kits available, your creativity is unlimited.

Contact Global Specialties for pricing.

Global Specialties
http://globalspecialties.com