Ever more from Moore

NEWS of the death of Moore’s law has always been greatly exaggerated. People started to pronounce it deceased not long after Gordon Moore, co-founder of Intel, a chipmaker, published on April 19th 1965 a paper arguing that the number of transistors that can be etched on a given surface area of silicon would double every year. In a later paper he corrected his forecast to every two years, which has come to be stated as his “law”. Regularly proving sceptics wrong, however, the exponential growth kept going (see chart), driving the digital revolution.

Yet signs are multiplying that half a century later, the law is running out of steam. It is not so much that physical limits are getting in the way—even though producing transistors only 14 nanometres (billionths of a metre) wide, the current state of the art can be quite tricky. Intel says that it can keep the law going for at least another ten years, eventually slimming its transistors down to 5nm, about the thickness of a cell membrane. Other than shrinking circuitry further, it has also started to stack components, in effect building 3D chips.

If Moore’s law has started to flag, it is mainly because of economics. As originally stated by Mr Moore, it was not just about reducing the size of transistors, but also lowering their price. And a few years ago, when transistors 28nm wide were the state of the art, chipmakers found their design and manufacturing costs beginning to rise sharply. New “fabs” (semiconductor fabrication plants) now cost more than $6 billion. In other words: transistors can be shrunk further, but they are now getting more expensive.

Makers of smartphones and other mobile devices will no doubt be keen for chipmakers to keep on packing ever more computing and storage power onto tiny slivers of silicon, and may even be prepared to accept their cost going up.

But compactness is less important for another fast-growing branch of the information-technology business, cloud computing. In cloud-service providers’ cavernous data centres, space is not at a premium, the way it is inside the latest iPhone. What increasingly matters most to cloud providers is energy efficiency: how much power their racks of servers consume, and how they can keep them sufficiently cool to ensure that their chips do not fry. Fortunately, one of the corollaries of Moore’s law is that the energy efficiency of transistors follows the same exponential law, doubling around every two years. And like the law itself, it’s not quite dead yet.