Collapsing Nanopillars Help To Build Chips - MIT

Producing Nano scale chips is the very thing which goes on in and out of a nanotechnology laboratory every day. Scientists sometimes achieve a certain break through and the only thing which remains is to shout "Eureka, Eureka". However no one was able to shout a 'Eureka' for developing a chip which is as small as the width of 30 atoms or 10 nm.

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Controlling the collapse of tiny pillars deposited on a silicon substrate can produce intricate patterns. | Image Credit: MIT

The feat is achieved by a group of researchers at #-Link-Snipped-# of Electronics and Singapore’s Engineering Agency for Science, Technology and Research. This is an unusual breakthrough because in Karl Berggren's own words they have made a hair to stand up straight which will try to wobble with every minute increase in its height. Karl Berggren an associate Professor of Electrical Engineering and Computer Science and also the person who led the group to the invention.

In making 10 nm wide chip, the researchers have tried to modify the photolithography technique which is conventionally used to produce minute nano scale chips. In this technique, a light sensitive material called resist is enveloped around the substrate. Then with the help of a stencil or Mask, the required part of resist is obstructed from view of light. The exposed part of resist hardens and the remaining part is removed through a process called as etching. In this way layer by layer is deposited on the surface and we get a chip.

However the main difficulty in doing this is the thickness of resist depends on the wavelength of light. A possible solution to this problem is to use a beam of light called e-beam. E- Beam is nothing but a narrow beam of light. However it takes much time in scanning the surface hence its efficiency is very low than had visible light been used in photolithography. Hence the light should be focused on a particular spot. For developing nano scale chips, the A*STAR scientists have to make arrangements that when the resist pillars are formed by the e-beam, the collapse in a direction opposite to each other.

Until now, they are not able to do that perfectly. Still, Joel Yang a PhD student working under Karl Berggren have shown that if a particular end of a pillar is flattened then the pillar falls in the intended direction. The process works with 98% reliability. The process is still not workable on an industrial scale but one day it will be. This marks an important step in production of chips and some time in near future we might have the mechanical systems in biosensors and in micro-fluidic and micro-mirror chips etc. It will be a matter of time that the group achieves a control over the nano structure assembly.