It's no secret that the clock speeds of processors have hit a glass ceiling. But until the latest iteration of the International Technology Roadmap for Semiconductors, we still expected them to increase by close to 10 per cent a year. Not anymore. The slow rise has been replaced by a crawl that acknowledges the need to keep both cost and power consumption under control.
The executive summary for the 2011 edition of the ITRS describes how an annual increase of 8 per cent is now down to 4 per cent, largely down to reductions in expected intrinsic transistor performance. Even this growth may be revised later this year, based on estimates of how improvements in transistor performance affect manufacturing cost.
One of the big problems is that scaling stopped contributing to transistor speed a while back and the possible upgrades will come through the use of multigate or fully depleted silicon on insulator transistors or the introduction of III/V materials. None of these options are cheap.
The upshot of the latest work is that clock speeds were predicted to exceed 10GHz by the end of the decade. In the latest ITRS, they are not expected to be greater than 6GHz even after another decade.
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