Moore’s Law, Part 2: More Moore and More than Moore

This is the second entry of a series focused on Moore’s Law and its implications moving forward, edited from a White paper on Moore’s Law, written by Google University Relations Manager Michel Benard. This series quotes major sources about Moore’s Law and explores how they believe Moore’s Law will likely continue over the course of the next several years. We will also explore if there are fields other than digital electronics that either have an emerging Moore's Law situation, or promises for such a Law that would drive their future performance.

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One of the fundamental lessons derived for the past successes of the semiconductor industry comes for the observation that most of the innovations of the past ten years—those that indeed that have revolutionized the way CMOS transistors are manufactured nowadays—were initiated 10–15 years before they were incorporated into the CMOS process. Strained silicon research began in the early 90s, high-κ/metal-gate initiated in the mid-90s and multiple-gate transistors were pioneered in the late 90s. This fundamental observation generates a simple but fundamental question: “What should the ITRS do to identify now what the extended semiconductor industry will need 10–15 years from now?”
- International Technology Roadmap for Semiconductors 2012

More Moore
As we look at the years 2020–2025, we can see that the physical dimensions of CMOS manufacture are expected to be crossing below the 10 nanometer threshold. It is expected that as dimensions approach the 5–7 nanometer range it will be difficult to operate any transistor structure that is utilizing the metal-oxide semiconductor (MOS) physics as the basic principle of operation. Of course, we expect that new devices, like the very promising tunnel transistors, will allow a smooth transition from traditional CMOS to this new class of devices to reach these new levels of miniaturization. However, it is becoming clear that fundamental geometrical limits will be reached in the above timeframe. By fully utilizing the vertical dimension, it will be possible to stack layers of transistors on top of each other, and this 3D approach will continue to increase the number of components per square millimeter even when horizontal physical dimensions will no longer be amenable to any further reduction. It seems important, then, that we ask ourselves a fundamental question: “How will we be able to increase the computation and memory capacity when the device physical limits will be reached?” It becomes necessary to re-examine how we can get more information in a finite amount of space.

The semiconductor industry has thrived on Boolean logic; after all, for most applications the CMOS devices have been used as nothing more than an “on-off” switch. Consequently, it becomes of paramount importance to develop new techniques that allow the use of multiple (i.e., more than 2) logic states in any given and finite location, which evokes the magic of “quantum computing” looming in the distance. However, short of reaching this goal, a field of active research involves increasing the number of states available, e.g. 4–10 states, and to increase the number of “virtual transistors” by 2 every 2 years.

More than Moore
During the blazing progress propelled by Moore’s Law of semiconductor logic and memory products, many “complementary” technologies have progressed as well, although not necessarily scaling to Moore’s Law. Heterogeneous integration of multiple technologies has generated “added value” to devices with multiple applications, beyond the traditional semiconductor logic and memory products that had lead the semiconductor industry from the mid 60s to the 90s. A variety of wireless devices contain typical examples of this confluence of technologies, e.g. logic and memory devices, display technology, microelectricomechanical systems (MEMS), RF and Analog/Mixed-signal technologies (RF/AMS), etc.

The ITRS has incorporated More than Moore and RF/AMS chapters in the main body of the ITRS, but is uncertain whether this is sufficient to encompass the plethora of associated technologies now entangled into modern products, or the multi-faceted public consumer who has become an influential driver of the semiconductor industry, demanding custom functionality in commercial electronic products. In the next blog of this series, we will examine select data from the ITRS Overall Roadmap Technology Characteristics (ORTC) 2012 and attempt to extrapolate the progress in the next 15 years, and its potential impact.

The opportunities for more discourse on the impact and future of Moore’s Law on CS and other disciplines are abundant, and can be continued with your comments on the Research at Google Google+ page. Please join, and share your thoughts.