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April 05, 2010

The World Electric – Part III

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The future of semiconductors? Imagine that it’s now the year 2093, two hundred years after the Columbian World’s Exposition of 1893 where Westinghouse lit the event with 100,000 incandescent bulbs amazing the Victorian visitors with artificial electric light.  In this future at the end of the 21st century the electronics industry has greatly matured and also diverged.  Micro-electromechanical Systems (MEMS) have merged with analog semiconductor technology to create entire laboratories on silicon and diamond that fit on a pinhead, while digital functions have moved to the quantum mechanical realm of matter.

Digital chips are no longer referred to as microelectronics but rather nano-electronics utilizing groups of quantum dots to form interconnects and logic.  Small geometry CMOS processes faded away around 2020 (the last were sub 16 nanometer 3D structures) with the introduction of production grade high temperature Double Electron-layer Tunneling Transistors (DELTT) and some limited quantum interference devices.  These quantum well devices were unipolar having both positive and negative transconductance based on gate voltage. This eliminated the need for complementary device types ("n" and "p") resulting in greatly simplified structures. These devices were eventually replaced with Quantum Dot Transistor (QDT) variants.

Logic is no longer based on electron currents but rather on electron position... using this method molecular size gates and functions are common place.  Computers now run at equivalent clock speeds exceeding 40,000 GHz (although no clock is running) thanks in part to quantum effects and new quantum architectures.  The additional byproduct is extremely high energy-efficiency resulting in almost no waste heat.

Analog semiconductors on the other hand have merged with nano-scale machines to form complete sensor and analysis engines on a single device.  These devices are so small and consume so little power that a complete health monitor fits into a ring the size of a wedding band. Utilizing mechanical and thermal energy harvesting, no batteries are required and communication with the "net" is accomplished through large arrays of nano-access-points spread like fertilizer across the countryside.  Even structures have pea-size sensors embedded right in the concrete mix during construction that utilize RF energy harvesting to relay the state and stresses providing status in real time.

The world of 2093 as seen in this vision would not exist if not for the never ending march of semiconductor performance - both analog and digital.  Many of these "proposals" of our future are based on research going on right now across many disciplines.  Economic progress dictates growth and if there is to be growth in the semiconductor industry, engineers and researchers will find ways to navigate the physical laws of our world to make gains in performance.  My vision is not everyone’s, but with some historical review, a look at current technologies in production, and a little bit of imagination I’m sure you can imagine the world of 2093 as I do... potentially so far advanced that we (like our Victorian predecessors holding an iPhone) would not even recognize the technology!  Comments are always welcome - until next time...

March 17, 2010

The World Electric – Part II

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IStock_000000387396XSmall As I discussed in part one of this series, electrical power and lighting was débuted at the 1893 World’s Columbian Exposition by Westinghouse and Nicola Tesla.  Now, a little over 100 years later we carry in our pockets technology so advanced that the Victorian era population would not even recognize it as such -  in fact, it may have been considered magic or supernatural.

But what is the next stop beyond the current generation of digital and analog semiconductor devices? I recently had a chance to talk with National Semiconductor’s Chief Technology Officer and Director of NS Labs, Dr. Ahmad Bahai.  I asked him what he thought of today’s high performance processes and the never ending progress to smaller geometries.  He said, “Analog scaling doesn’t buy you any performance advantage” – primarily due to the way the transistors are used.  Analog functions still require isolation and moving things closer only complicates the issue.

Digital processes use transistors as switches avoiding the “in-between” or linear regions of the devices.  Analog semiconductors actually take advantage of the linear region to provide amplification and accurate control of voltage and current.  In mixed signal semiconductors such as Analog to Digital Converters (ADCs), there is a percentage of digital logic, but it is usually such as a small percentage of the function that shrinking it doesn’t provide great benefit.

I also asked him what he thought about digital process nodes below 22nm.  He made an interesting comment, “below 22nm is it (the semiconductor) electrical or mechanical?” This raises an interesting question… at these tiny geometries is it easier to build switches from mechanical functions? With so much research going on with carbon nano-tubes, it may remain in the realm of electrical for the near term. This along with the ability to stack circuits may continue to raise the transistor count to give Moore’s law another 10+ years.

For now the move in analog semiconductors will be to enhanced processes such as Silicon Nitride (SiN), Silicon Carbide (SiC), Gallium Nitride (GaN) and other familiar materials to increase the power handling capability – a property very important to energy management and technologies such as the Smart Grid. Beyond that, you’ll have to wait until part III… till next time…

February 24, 2010

The World Electric – Part I

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TWE At the 1893 World’s Columbian Exposition (aka: Chicago World’s Fair) Westinghouse and Nikola Tesla introduced the world to alternating current as well as the Westinghouse brand light bulb of which 100,000 were used to light the event. There was a great optimism with regards to technology and the future during that period and a little over 110 years later I believe that enthusiasm still survives.  The idea of an electric world where everything would be powered by this magical force won over many of the visitors to the fair and set in motion a technological revolution.

Today, electric power is so common, that it is considered ubiquitous and quickly obvious by its absence.  It is unthinkable that a residential or commercial structure would lack electric services.  Our very existence is dependant on electric power and without it much of the world would die due to starvation and disease.  We often take this modern marvel for granted and realize just how much we depend on it when it’s not there (I have first hand accounts during the 2004 Florida hurricane season when friends lost power for weeks).

So looking forward into the 21st century, how will electricity be viewed in 2093 - 200 years after the 1893 event? I think it will be considered the primary power source for everything including all transportation and personal vehicles.  The raw energy sources for the current state-of-the-art power plants come from many different forms and many rely on carbon based fuels.  This will shift eventually toward cleaner forms of energy such as harvesting (e.g. wind, solar, wave, etc) and other nuclear methods (e.g. LFTR technology, fusion, etc. - see my post, "The End Of The Carbon Age"). This shift will provide electrical power at lower costs, and combined with improved storage and transmission technologies will finally give us an all-electric infrastructure.

But what is the future of the semiconductor industry in an all-electric world? It is hard to fathom how semiconductors of the late 21st century might be fabricated or what functions they may provide.  Carbon nano-tubes may replace silicon as the material of choice in future devices - as Yoda might say, "The future, cloudy it is..."  But there can be no doubt that semiconductor nanotechnology will be central to the everyday life of the citizens of that era just as it is today. It is difficult in our modern world to avoid using something that does not contain electronics. So the next time you pick up your cell phone to text your friend, log-on to the W3 or play that game with your PS3, remember to thank a semiconductor engineer (or any engineer for that matter). 

Over the next several weeks I will be exploring possible technologies that may emerge as the functional device building blocks of the next wave of semiconductors.  There are so many candidates I will try to focus on the key technologies so reasonable predictions can be made.  So get out your virtual time machine and let’s take a look into the future... cloudy as it may be! Till next time...