Moore’s law really is dead this time
The chip industry is no longer going to treat Gordon Moore’s law as the target to aim for.
By Peter Bright
Feb 10 2016
Moore’s law has died at the age of 51 after an extended illness.
In 1965, Intel co-founder Gordon Moore made an observation that the number of components in integrated circuits was doubling every 12 months or so. Moreover, as this site wrote extensively about in 2003, that the number of transistors per chip that resulted in the lowest price per transistor was doubling every 12 months. In 1965, this meant that 50 transistors per chip offered the lowest per-transistor cost; Moore predicted that by 1970, this would rise to 1,000 components per chip, and that the price per transistor would drop by 90 percent.
With a little more data and some simplification, this observation became “Moore’s law”: the number of transistors per chip would double every 12 months.
Gordon Moore’s observation was not driven by any particular scientific or engineering necessity. It was a reflection on just how things happened to turn out. The silicon chip industry took note and started using it not merely as a descriptive, predictive observation, but as a prescriptive, positive law: a target that the entire industry should hit.
Hitting this target didn’t happen by accident. Building a silicon chip is a complex process, and it uses machinery, software, and raw materials that are sourced from a number of different companies. To ensure that all the different players are aligned and working on compatible timetables to preserve Moore’s law, the industry has published roadmaps laying out the expected technologies and transitions that will be needed to preserve Moore’s law. The Semiconductor Industry Association, a predominantly North American group that includes Intel, AMD, TSMC, GlobalFoundries, and IBM, started publishing roadmaps in 1992, and in 1998 the SIA joined up with similar organizations around the world to produce the International Technology Roadmap for Semiconductors. The most recent roadmap was published in 2013.
Problems with the original formulation of Moore’s law became apparent at an early date. In 1975, with more empirical data available, Gordon Moore himself updated the law to have a doubling time of 24 months rather than the initial 12. Still, for three decades, simple geometric scaling—just making everything on a chip smaller—enabled steady shrinks and conformed with Moore’s prediction.
In the 2000s, it was clear that this geometric scaling was at an end, but various technical measures were devised to keep pace of the Moore’s law curves. At 90nm, strained silicon was introduced; at 45nm, new materials to increase the capacitance of each transistor layered on the silicon were introduced. At 22nm, tri-gate transistors maintained the scaling.
But even these new techniques were up against a wall. The photolithography process used to transfer the chip patterns to the silicon wafer has been under considerable pressure: currently, light with a 193 nanometre wavelength is used to create chips with features just 14 nanometres. The oversized light wavelength is not insurmountable but adds extra complexity and cost to the manufacturing process. It has long been hoped that extreme UV, with a 13.5nm wavelength, will ease this constraint, but production-ready EUV technology has proven difficult to engineer.
Even with EUV, it’s unclear just how much further scaling is even possible; at 2nm, transistors would be just 10 atoms wide, and it’s unlikely that they’d operate reliably at such a small scale. Even if these problems were resolved, the specter of power usage and dissipation looms large: as the transistors are packed ever tighter, dissipating the energy that they use becomes ever harder.
The new techniques, such as strained silicon and tri-gate transistors, took more than a decade to put in production. EUV has been talked about for longer still. There’s also a significant cost factor. There’s a kind of undesired counterpart to Moore’s law, Rock’s law, which observes that the cost of a chip fabrication plant doubles every 4 years. Technology may provide ways to further increase the number of transistors packed into a chip, but the manufacturing facilities to build these chips may be prohibitively expensive—a situation compounded by the growing use of smaller, cheaper processors.
Moore’s law really is dead this time