The Predicted demise of microchip manufacturing using lithographic processes over the next 10 to 20 years may have been averted. A new technique has been devised that enables the continued miniaturisation of chips using a quantum physics phenomenon to adapt conventional lithographic processes.
Scientists have shrunk microchips, containing millions of transistors, to smaller and smaller sizes, resulting in faster processing speeds. Currently computer chips have transistors that are about 2,000 atoms wide.
Lithography is seen as the fastest and most efficient chip manufacturing technique available. Most chip designers believe it will be feasible to create features as small as 250 atoms wide, but that will not be possible for another 10–15 years.
Beyond this point an optical effect known as the Rayleigh criterion comes into play, which says that the deep ultraviolet light used to etch the surface of silicon cannot create transistors smaller than 124 atoms wide.
Until recently, this had been seen as the ultimate theoretical limit of chip miniaturisation using conventional lithographic processes. But now, physicists at NASA’s Jet Propulsion Laboratory and the California Technology Institute believe they can create features which are half this size.
They are convinced that features as tiny as 62 atoms wide could be created via a quantum physics process known as ‘entanglement’.
It works like this: the stream of particles in a light wave (the photons) are usually unaffected by one another, but sometimes two or more photons can become ‘entangled’, whereby the properties of one photon depend upon the properties of another — a phenomenon Einstein referred to as ‘spooky light’.
In the laboratory, entangled photons can be produced by passing a light beam through a special crystal, and could produce features on a silicon wafer much smaller than the wavelength of conventional ultraviolet light.
If successful, this technique could create chips with processing speeds thousands of times faster than existing microchips.