Analysis: The end of silicon?

By Barry Collins

Posted on 24 Mar 2005 at 13:41

If you marvel at the array of silicon circuitry wedged inside today's computers, prepare to be amazed. Semiconductors made out of the smallest particles known to man and plastic computer memory are two technologies that could feature in PCs just a decade from now.

As any seasoned techie will know, the days of conventional chips are numbered. Moore's Law, which states that the number of transistors you can fit on a silicon chip will double every two years, could expire within the decade. Chipmakers are frantically trying to find a substitute for silicon, and computing giant HP claims that it may have the answer - molecules.

HP says it can replace traditional transistors with grids of microscopic wires that have molecules of acid placed at the points where the wires intersect. Electrical signals will be passed through these so-called 'crossbar latches' so they can perform the logic functions that drive a computer.

The crossbar latches are the very definition of minute. Today's silicon-based transistors are roughly 90 nanometres long - the crossbar latch will work in a space of just 2-3 nanometres, meaning you could squeeze thousands of them into an area the width of a human hair.

Making semiconductors out of such nanotechnology will not only allow chipmakers to produce vastly more powerful chips, it will mean processing power can be squeezed into ever-tinier devices.

'The crossbar latches are intended to work at the molecular scale at which silicon transistors will no longer be able to operate, because of quantum effects,' said Dave Berman, manager of HP Labs' media relations department.

A move into semiconductor production would represent quite a departure for HP, which is better known for its printer and PC business. Yet, the expertise it has gained in the printing business could be applied in its new venture.

'There are proposals to use inkjet technology to create semiconductor chips,' said Berman. 'The present method proposed for creating the crossbar latches would involve a technology called nano-imprint lithography, essentially a type of "stamping" process at the molecular scale.'

The crossbar latches have another huge advantage over their flagging predecessors - flaws in manufacturing are easier to spot. The likes of Intel spend hundreds of millions on quality control, only for faulty batches of chips to occasionally slip through the net, resulting in expensive recalls.

HP claims its molecular chips could become commercially viable by 2012 - and by the time they reach the market, they could be driving a PC with memory made of plastic.

This is the vision of a team of researchers from Johannes Kepler University in Austria. They have adapted a technology used to make the tie-clip microphones worn by television presenters into a device capable of storing the millions of binary digits floating around a computer's memory.

The memory chip stores the 1s and 0s of computer information as one of two electric polarisation directions. A thin sliver of polyvinyl alcohol in the memory chip captures the electrical charges, essentially imprisoning the computer's data in the plastic material.

The prototype developed by the Austrian team stored data for 15 hours after power was switched off. However, there's much work to be done on improving plastic's conductivity, which is currently at the very weakest end of all the materials used for today's memory chips. As a result, it could be ten years before the technology can be turned into inexpensive computer memory, and in the meantime it's more likely to be found in ID tags or smart cards.