Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:


2-photon absorbing molecules fabricate polymer features just 65 nanometers wide

Producing three-dimensional polymer line structures as small as 65 nanometers wide just became easier with new two-photon absorbing molecules that are sensitive to laser light at short wavelengths, allowing researchers to create them without highly sophisticated fabrication methods.
Fabricating such small features normally requires expensive electron beam or extreme ultraviolet lithography equipment. However, using a technique called 3D multi-photon lithography simplifies the process and reduces the cost. The technique could compete with existing processes for fabricating nanoscale electronic, photonic and microfluidic devices.

"Being able to obtain line widths down to 65 nanometers, which is substantially below prior published work of 100 nanometers, opens up new applications for multi-photon lithography," said Joseph Perry, a professor in the Georgia Tech School of Chemistry and Biochemistry and the Center for Organic Photonics and Electronics.

The technique scans a laser beam across a substrate coated with a polymer resin containing a unique dye to create a desired hardened polymer structure. The laser writing process takes advantage of the fact that the chemical reaction of cross-linking occurs only where molecules have absorbed two photons of light. Since the rate of two-photon absorption drops off rapidly with distance from the laser's focal point, only molecules at the focal point receive enough light to absorb two photons.

The fabrication method and dye were described in the March 19 issue of Optics Express. The research was supported by the Office of Naval Research APEX Consortium and the National Science Foundation, through the Science and Technology Center for Materials and Devices for Information Technology Research.

Seth Marder and Stephen Barlow, also researchers in the School of Chemistry and Biochemistry and the Center for Organic Photonics and Electronics, synthesized the unique molecule called DAPB, 4,4'-bis(di-n-butylamino)biphenyl, to initiate the chemical reaction leading to the hardening of the polymers when exposed to laser light.

"We needed a dye with good two-photon absorption at a wavelength of 520 nanometers, so we tried DAPB," explained Perry. "DAPB proved to be very effective in this kind of lithography."

The molecule developed by Marder and Barlow is about ten times more efficient at absorbing light by two photon absorption than commercial ultraviolet photoactive materials. That efficiency allowed Perry and graduate students Wojciech Haske and Vincent Chen, research scientist Joel Hales and postdoctoral associate Wenting Dong to create 3D patterns with nanoscale lines at light intensities low enough to avoid damaging the polymers.

For the experiments, a film of the polymer resin containing DAPB was formed. When the film was exposed to the focused laser, DAPB was excited and triggered cross-linking, leaving the insoluble scanned structure on the surface of a substrate when placed in a developer solution.

Since Perry controls where the Ti: Sapphire pulsed laser scans with a computer program, the polymers can be cross-linked in any pattern including 3D stacks of straight lines that are connected and sturdy. The laser beam is turned on to expose lines of polymer and off when no line should be drawn.

Conventional lithography involves creating a specific pattern on a mask for each new layer and exposing each layer to light and developing it. With this new technique, three-dimensional layered nanostructures can be created simply by having a computer program scan a different pattern for each layer. Mask templates become unnecessary and the coating, exposing and developing processes only have to be conducted once.

"We can create essentially any pattern we want. For this work, some of the patterns look like walls or lines suspended across walls and some are like a tall stack of crisscrossed lines," noted Perry.

Perry and Marder co-founded a company in 2003 called Focal Point Microsystems that is working to commercialize this fabrication technology.

"We can write very small lines and create stacked-up grids of lines called photonic crystals," explained Perry. "This work shows that we can fabricate functional photonic micro-devices with tailored transmission capabilities."

It takes only 10 minutes to create a 20 micron by 20 micron structure with 30 layers, Perry added. Perry envisions using this technology to create compact micro-spectrometers on a chip for use in telecommunications and sensors. It may also be used as a compact way to separate the multiple wavelengths traveling through a fiber optic cable.

This type of simple, table-top technology may also be useful to fabricate customized types of circuits with many layers, which would be extremely expensive with standard methods because each layer would require a special mask.

"With the combination of the right molecule and short wavelength light, we've demonstrated that we can obtain nanoscale features. We're at 65 nanometers now and we're still trying to go smaller," said Perry.

John Toon | EurekAlert!
Further information:

More articles from Physics and Astronomy:

nachricht Finding the lightest superdeformed triaxial atomic nucleus
20.10.2016 | The Henryk Niewodniczanski Institute of Nuclear Physics Polish Academy of Sciences

nachricht Innovative technique for shaping light could solve bandwidth crunch
20.10.2016 | The Optical Society

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: New 3-D wiring technique brings scalable quantum computers closer to reality

Researchers from the Institute for Quantum Computing (IQC) at the University of Waterloo led the development of a new extensible wiring technique capable of controlling superconducting quantum bits, representing a significant step towards to the realization of a scalable quantum computer.

"The quantum socket is a wiring method that uses three-dimensional wires based on spring-loaded pins to address individual qubits," said Jeremy Béjanin, a PhD...

Im Focus: Scientists develop a semiconductor nanocomposite material that moves in response to light

In a paper in Scientific Reports, a research team at Worcester Polytechnic Institute describes a novel light-activated phenomenon that could become the basis for applications as diverse as microscopic robotic grippers and more efficient solar cells.

A research team at Worcester Polytechnic Institute (WPI) has developed a revolutionary, light-activated semiconductor nanocomposite material that can be used...

Im Focus: Diamonds aren't forever: Sandia, Harvard team create first quantum computer bridge

By forcefully embedding two silicon atoms in a diamond matrix, Sandia researchers have demonstrated for the first time on a single chip all the components needed to create a quantum bridge to link quantum computers together.

"People have already built small quantum computers," says Sandia researcher Ryan Camacho. "Maybe the first useful one won't be a single giant quantum computer...

Im Focus: New Products - Highlights of COMPAMED 2016

COMPAMED has become the leading international marketplace for suppliers of medical manufacturing. The trade fair, which takes place every November and is co-located to MEDICA in Dusseldorf, has been steadily growing over the past years and shows that medical technology remains a rapidly growing market.

In 2016, the joint pavilion by the IVAM Microtechnology Network, the Product Market “High-tech for Medical Devices”, will be located in Hall 8a again and will...

Im Focus: Ultra-thin ferroelectric material for next-generation electronics

'Ferroelectric' materials can switch between different states of electrical polarization in response to an external electric field. This flexibility means they show promise for many applications, for example in electronic devices and computer memory. Current ferroelectric materials are highly valued for their thermal and chemical stability and rapid electro-mechanical responses, but creating a material that is scalable down to the tiny sizes needed for technologies like silicon-based semiconductors (Si-based CMOS) has proven challenging.

Now, Hiroshi Funakubo and co-workers at the Tokyo Institute of Technology, in collaboration with researchers across Japan, have conducted experiments to...

All Focus news of the innovation-report >>>



Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

Agricultural Trade Developments and Potentials in Central Asia and the South Caucasus

14.10.2016 | Event News

World Health Summit – Day Three: A Call to Action

12.10.2016 | Event News

Latest News

Innovative technique for shaping light could solve bandwidth crunch

20.10.2016 | Physics and Astronomy

Finding the lightest superdeformed triaxial atomic nucleus

20.10.2016 | Physics and Astronomy

NASA's MAVEN mission observes ups and downs of water escape from Mars

20.10.2016 | Physics and Astronomy

More VideoLinks >>>