One of the biggest roadblocks to nanoscale engineering is the precise placement of individual atoms. To date, nanoscale manufacturing has been accomplished by randomly depositing, or growing, the desired materials onto substrates and hoping that they form the appropriate structures or by using various forms of lithography, an expensive and waste prone reductive process similar to sculpting.
Researchers at Boston University, in work recently published in “Nano Letters”, and described by some as spray painting with atoms, have lept over the precision roadblock with a cost effective and scaleable MEMS, Microelectromechanical system, device that can precisely place individual atoms.
Their device is comprised of a comb actuator, an aperture that ranges from .5µms to 2 µms in diameter, a high speed shutter that can open and close in less than 100 microseconds(100 millionths of a second)situated on a central plate that is suspended by four doubly folded flexure springs and tethers above a Silicon nitride chip.
The device is “packaged and ball bonded into an 8 pin
DIP chip holder and covered with a lid containing a ~75 µm hole centered over the plate.”
In other words, these researchers have created a “Fab on a chip”. The whole system is roughly 1/8th the size of a dime, has a current feature resolution of less than 50 nanometers (soon to be below 10 nm), and can be used to build the next generation of electronic circuits and structures from the bottom up.
The structure of the system lends itself to use in an array and will enable future researchers and manufacturers to write complex structures and circuits at the nanoscale. This will reduce the cost of electronics manufacturing and will enable increased complexity in chip design.
“In operation, we envision using an array of holes, writing larger structures first with larger apertures. The smaller holes are kept clean with the shutter until needed.”
This device is capable of producing features that are smaller than all but the most advanced nanoscale techniques at present. But instead of wasting tremendous amounts of material, this system will, when it is fully developed, be capable of producing even finer features, below 10 nm, something that the most advanced lithographic techniques available today simply cannot achieve.
“A MEMS shutter makes it possible to stochastically control the number of atoms passing through the aperture down to an order of one. This will enable new mesoscopic experiments of quench condensed films, quantum dots and single atom effects.”
By William Tatum