Placing components on microchips could be easier and cheaper with a new technique that exploits electric fields, writes John Moore.
Researchers in Cork have developed a "hands-free" way of putting tiny electronic components onto microchips. Electric fields rather than mechanical means guide the minute components into place.
The technique is under study at the National Microelectronics Research Centre, at University College Cork. Instead of using conventional robotic micro-tweezers to put components onto a silicone chip, they're using the electric fields to do the job much faster and cheaper.
The technique, called field configurable assembly, exploits the fact that, as most electronic devices are charged, an electric field generated at a specific site on a chip can be used to position the charged component.
Dr Gareth Redmond of the research centre's nanotechnology department is using the technique to manipulate mesoscale components - objects measuring from between a millimetre and a thousand-millionth of a metre.
"First of all, instead of having the chip in a dry environment, as is presently done in a commercial-assembly set-up, we place the chip under a specially prepared liquid solution," explains Redmond.
"We then take, say, a jam jar of identical components mixed up in a liquid and literally pour them randomly over the surface. As we switch on the electric fields each electrical receptor site acts as a kind of hook and pulls in a separate component, where they then localise."
Afterwards, says Redmond, they wash off the excess, pour on another batch of components for different receptor sites and repeat the process.
A typical commercial optoelectronic assembly machine can, in an hour, handle up to 250 components with a minimum size of 250 micrometres (a micrometre is a millionth of a metre). The new technique could handle up to 3,000 devices of as little as 50 micrometres in size.
The centre's research, which is supported by funding from the European Union and Enterprise Ireland, is the only work of its type in Europe.
"Our research was inspired by processes we observed in biology," says Redmond. "Most of us have chemistry backgrounds, and we were looking at things like, for example, how a DNA molecule was naturally pre-programmed to come together in a self-assembly process."
In the next few months Redmond and his team hope to publish research about another assembly technique they are working on, called capillary assembly. Instead of using electric fields, this method involves putting components into a vat of water, shaking them about and letting the components assemble together.
They then hope to broaden their research into assembly technology, extending it to the nanotechnology level, where engineering of future components will be at a scale and size approaching those of individual atoms.
"There are enormous challenges to integration and assembly of objects you can't physically see, and this technology is a potential manufacturing paradigm for future nanoscale integrated circuits."
You can find out more about the National Microelectronics Research Centre's work at www.nmrc.ie