Water could be the key to cheaper nanoelectronics!

Previously we saw that water could play a role in enhancing the density of memory storage devices. (http://nanosciencetech.blogspot.com/2008/11/ultra-dense-memory-storage-devices.html).

Now a recent study at the Kavli Institute of Nanoscience in DELFT, Netherlands shows that a splash of the wet stuff could help make nanoelectronic manufacturing both quicker and cheaper.

Now days, nanoscale components are embedded in the electronic circuit boards, but they are very difficult and they require superior level of accuracy. To get complicated nanostructures nanostructures on a silicon chip it is sometimes necessary to grow them in separate layers and then transfer these one by one onto the final chip (PDF) to build them into working components.

Often it takes strong chemicals to separate the layers from the surface on which they are grown, and high temperatures may be needed to activate the thermal adhesives that keep the components in place at their destination.

Researchers have found a way to use water to transfer layers quickly and easily from one surface to another. They exploit the fact that different materials have different hydrophilicity defined by the tendency to attract water through transient hydrogen bonds.

The team took a relatively hydrophilic silicon wafer onto which a graphene structure had been deposited in the desired pattern. Then they dipped it into a solution containing a hydrophobic polymer that dried to form a strong, solid hydrophobic layer on top of the wafer.

Next, they submerged the silicon wafer in water. Because graphene is equally hydrophobic, the water molecules wiped out both layers out of the way to wet the hydrophilic silicon beneath it, gradually "wedging" them off the silicon base. The polymer-graphene film then floated to the surface of the water.

Now the team placed a second silicon wafer beneath the floating film and used a needle to prod the film into position before draining away the water. Intermolecular forces between the graphene and silicon then provide a surprisingly stable attachment.

They then dissolved away the hydrophobic polymer to leave the graphene attached to the new wafer. Repeating the technique several times would allow graphene layers to be built up into a complex electronic nanostructure.