Wednesday, December 28, 2016

What's Happening to Moore's Law?

By Wgsimon (Own work) [CC BY-SA 3.0 ( or GFDL (], via Wikimedia Commons
By Wgsimon (Own work) via Wikimedia Commons
The magical promise of electronics is in trouble. Moore's Law, the observation that the number of transistors in a dense integrated circuit (IC) doubles approximately every two years, has been straining at the seams. The problem is although  Richard Feynman assured us "There's Plenty of Room at the Bottom", those darn asymptotes sure do get in the way.

In this case, the asymptote is zero:

As you can see, things were really streaking along at first. However, as the years turn into decades and we get close to 50 years into it, things are getting extremely small. Look at this blow-up of the final 16 years:

What is causing all the problems? Amazing things, actually. Getting rid of waste heat from all of those transistors packed together is certainly one of them. That is why voltages have dropped from a "massive" 5V to a more manageable 3.3V and even 1.8V. Of course, when the signal voltage gets smaller, noise voltage becomes more of a problem. Also, the amount of charge being used for storing a bit gets smaller and smaller and alpha particles can cause problems.

Light has become way too big. Those "huge" 400 nm wavelength violet colored light beams are just too coarse for photolithography anymore. Ultraviolet (400 nm down to 125 nm wavelength) and then Extreme Ultraviolet (124 nm down to 10nm wavelength) radiation has become necessary.

Then there is contamination. A dust mote becomes a huge problem considering that a smoke particle only gets as small as 300 nm and face powder dust is 100 nm. This comparison chart should help put all of this into perspective:
By Cmglee (Own work) via Wikimedia Commons
When you get to the point that the HIV virus looks big in comparison, the clean room where you make your (ICs) had better be spotless. Consider this: the outside air in a typical urban area contains 35 million 0.5 μm and larger particles per cubic meter, corresponding to an ISO 9 cleanroom. However, an ISO 1 cleanroom allows only 12  0.3 μm and smaller particles per cubic meter.

Even with all of this, we're in trouble so where do we go from here? Well, just like builders in New York City and Chicago learned in the 1880s and beyond, at some point the only place left to go is up! So, ICs at long last have started to go 3D. Of course, 3D has lots of meanings in this arena. It is a broad term that includes technologies like 3D wafer-level packaging, 3D systems integration,  2.5D and 3D interposer-based integration, 3D stacked ICs, monolithic 3D ICs, and 3D integration of heterogeneous pieces. Whatever it is, it means we get to continue to reap the benefits of the cheap, plentiful computing that is driving civilization to amazing new things everyday.

Gordon Moore is no longer with us, but I think he'd be impressed if he were.

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