Scientists draw semiconductor circuits with super-fine ink-jet printers

Posted by Rick C. Hodgin

Urbana (IL) - Scientists at the University of Illinois have developed a new type of ink-jet printer capable of drawing 700 nm lines and 250 nm dots on circuit boards.  They've demonstrated the ability to reliably print circuit patterns which work, thereby ushering in a whole new generation of fast-cycle tools.

Several scientific disciplines have joined forces to create a practical form of nanoscale printer.  The electro-hydro-dynamic jet, or e-jet printers operate similarly to ink-jet printers.  They can produce remarkably higher resolutions, however.  So much higher they can even be used to "print" circuit boards and "draw" circuits onto displays and photovoltaic modules, as well as a host of similar devices.  Basically, if it exists in 3 dimensions, is comprised of layers, and can be drawn onto a substrate material, then this new printer can do it.

 

The e-jet printers uses an array of gold-plated, teflon-coated, 300 nm micro-nozzles.  The fluid is electrically induced to flow out of the nozzle.  This induction technique differs from traditional ink-jet printers which typically pulse out the ink mechanically.  While this form of electrically induced flow technology is not new, this particular application and the refinements they've developed are.  They now have the ability to deliver a wide range of "ink sources" and have produced a real-world product with much utility.

A member of the mechanical engineering team, Placid Ferreira, said "...this work opens up the possibility for low-cost and high-performance printed electronics and other systems that involve materials that cannot be manipulated with more common patterning methods derived from microelectronics fabrication."  A materials scientist named John Rogers said "We have invented methods ... that can produce patterns and functional devices that establish new resolution benchmarks for liquid printing, significantly exceeding those of established ink-jet technologies."

Wide applications are possible including even some unlikely uses, such as printing micro-arrays of DNA spots for different forms of bio-analysis.  Today, circuit-boards using arrays of single-walled carbon nanotubes as the semiconductor have already demonstrated that traditional transistors (with both source and drain electrodes) printed on plastic substrates work.  They not only functioned properly, but they had similar characteristics to products built using the more conventional lithography techniques.

Software has been created which allows for rapid duplication and even production line generation.  The technology is scalable and carries with it a programmable reservoir source for fluid delivery.  This enhanced fluid delivery system can allow last-second pre-processing before passing through the e-jet nozzles.  This might include mixing two materials together which might have a short liquid lifetime before setting.  Applications using a wide range of organic and inorganic "inks" have already been demonstrated.  These support the extremely fine 250 nm dot resolution.  Also, suspended solids have been demonstrated with resolutions below 1,000 nm (1 micron).

This technology was created by a team comprised of materials scientists, chemists, mechanical engineers, electrical engineers and physicists all working together at the Center for Nanoscale Chemical Electrical Manufacturing Systems in Urbana.  Their work was funded by the National Science Foundation.