Plugging the leaks

MOORE’S LAW—the prediction made in 1965 by Gordon Moore, that the number of transistors on a chip of given size would double every two years—has had a good innings. The first integrated circuit (invented by Jack Kilby of Texas Instruments, see above) was a clunky affair. Now the size of transistors is measured in billionths of a metre. Moore’s law has yielded fast, smart computers, with pretty graphics and worldwide connections. It has thereby ushered in an age of information technology unimaginable when Dr Moore coined it. Not bad going for what was originally just an off-the-cuff observation.

That observation, however, is not truly a law. It is, rather, the description of a journey of many steps, each a specific technological change (see chart below). That new steps will happen is as much an article of faith as a prediction. Every time transistors shrink, they get closer to the point where they can shrink no further—for if the law continues on its merry way, transistors will be the size of individual silicon atoms within two decades.

More to the point, they have already shrunk to a size where every atom counts. Too few atoms can cause their insulation to break down, or allow current to leak to places it is not supposed to be because of a phenomenon called quantum tunnelling, in which electrons vanish spontaneously and reappear elsewhere. Too many atoms of the wrong sort, though, can be equally bad, interfering with a transistor’s conductivity. Engineers are therefore endeavouring to redesign transistors yet again, so that Dr Moore’s prediction can remain true a little longer.