Nanotechnology Now

Our NanoNews Digest Sponsors
Heifer International



Home > Press > Princeton engineers develop low-cost recipe for patterning microchips

Fracture-induced structuring results in the self-formation of periodic lines, or gratings, separated by as few as 60 nanometers -- less than one ten-thousandth of a millimeter -- on microchips. First, a thin polymer film is painted onto a rigid plate, such as a silicon wafer. Then, a second plate is placed on top, creating a polymer sandwich that is heated to ensure adhesion. Finally, the two plates are pried apart. As the film fractures, it automatically breaks into two complementary sets of nanoscale gratings, one on each plate.

Credit: Stephen Chou/Princeton University
Fracture-induced structuring results in the self-formation of periodic lines, or gratings, separated by as few as 60 nanometers -- less than one ten-thousandth of a millimeter -- on microchips. First, a thin polymer film is painted onto a rigid plate, such as a silicon wafer. Then, a second plate is placed on top, creating a polymer sandwich that is heated to ensure adhesion. Finally, the two plates are pried apart. As the film fractures, it automatically breaks into two complementary sets of nanoscale gratings, one on each plate.

Credit: Stephen Chou/Princeton University

Abstract:
Creating ultrasmall grooves on microchips -- a key part of many modern technologies -- is about to become as easy as making a sandwich, using a new process invented by Princeton engineers.

Princeton engineers develop low-cost recipe for patterning microchips

Princeton, NJ | Posted on September 2nd, 2007

The simple, low-cost technique results in the self-formation of periodic lines, or gratings, separated by as few as 60 nanometers -- less than one ten-thousandth of a millimeter -- on microchips. Features of this size have many uses in optical, biological and electronic devices, including the alignment of liquid crystals in displays. The researchers will publish their findings Sept. 2 in the online version of Nature Nanotechnology.

"It's like magic," said electrical engineer Stephen Chou, the Joseph C. Elgin Professor of Engineering. "This is a fundamentally different way of making nanopatterns."

The process, called fracture-induced structuring, is as easy as one-two-three. First, a thin polymer film is painted onto a rigid plate, such as a silicon wafer. Then, a second plate is placed on top, creating a polymer sandwich that is heated to ensure adhesion. Finally, the two plates are pried apart. As the film fractures, it automatically breaks into two complementary sets of nanoscale gratings, one on each plate. The distance between the lines, called the period, is four times the film thickness.

The ease of creating these lines is in marked contrast to traditional fabrication methods, which typically use a beam of electrons, ions, or a mechanical tip to "draw" the lines into a surface. These methods are serial processes which are extremely slow and therefore only suitable for areas one square millimeter or smaller. Other techniques suitable for larger areas have difficulties achieving small grating periods or producing a high yield, or they require complex and expensive processes. Fracture-induced structuring is not only simple and fast, but it enables patterning over a much larger area. The researchers have already demonstrated the ability of the technique to create gratings over several square centimeters, and the patterning of much large areas should be possible with further optimization of the technique.

"It's remarkable - and counterintuitive - that fracturing creates these regular patterns," said chemical engineering professor and dean of Princeton's graduate school William Russel. Russel and his graduate student Leonard Pease III teamed with Chou and his graduate students Paru Deshpande and Ying Wang to develop the technique.

A patent application has been filed on the process, which the researchers say is economically feasible for large-scale use in industry. The gratings generated by the fracturing process also could be used in conjunction with existing patterning methods. For example, the nanoimprinting method invented by Chou in the 1990s can use the gratings generated by fracture-induced structuring to create a mold that enables mass duplication of patterns with high precision at low cost.

As with many scientific discoveries, the fracture-induced structuring process was happened upon accidentally. Graduate students in the Chou and Russel groups were trying to use instabilities in various molten polymers (in essence, melted plastic) to create patterns when they discovered instead that fracturing a solid polymer film can generate the gratings automatically. The team seized upon this finding and established the optimal conditions for grating formation.

Next, the group plans to explore the fundamental science behind the process and investigate the interplays of various forces at such a small scale, according to Chou.

"And, we want to push the limit and see how small we can go," he said.

Abstract: Self-formation of sub-60-nm half-pitch gratings with large areas through fracturing

Periodic micro- and nanostructures (gratings) have many significant applications in electronic, optical, magnetic, chemical and biological devices and materials. Traditional methods for fabricating gratings by writing with electrons, ions or a mechanical tip are limited to very small areas and suffer from extremely low throughput. Interference lithography can achieve relatively large fabrication areas, but has a low yield for small-period gratings. Photolithography, nanoimprint lithography, soft lithography and lithographically induced self-construction all require a prefabricated mask, and although electrohydrodynamic instabilities can self-produce periodic dots without a mask, gratings remain challenging. Here, we report a new low-cost maskless method to self-generate nano- and microgratings from an initially featureless polymer thin film sandwiched between two flat relatively rigid plates. By simply prying apart the plates, the film fractures into two complementary sets of nonsymmetrical gratings, one on each plate, of the same period. The grating period is always four times the thickness of the glassy film, regardless of its molecular weight and chemical composition. Periods from 120 nm to 200 mm have been demonstrated across areas as large as two square centimeters.

####

About Princeton University
The School of Engineering and Applied Science at Princeton, like the University itself, is unique in combining the strengths of a world-leading research institution with the qualities of an outstanding liberal arts college. Princeton Engineering conducts about $50 million a year in research funded by government agencies and industry in areas ranging from biological sensors to aerospace engineering to next-generation Internet design. At the same time, every faculty member – from new professors to Nobel laureates – teaches undergraduate and graduate students. The school also is proud of the many humanities majors and other non-engineers who choose to take its numerous courses that connect technical subjects with business, history, public policy, entrepreneurship and the arts.

For more information, please click here

Contacts:
Hilary Parker

609-258-4597

Copyright © Princeton University

If you have a comment, please Contact us.

Issuers of news releases, not 7th Wave, Inc. or Nanotechnology Now, are solely responsible for the accuracy of the content.

Bookmark:
Delicious Digg Newsvine Google Yahoo Reddit Magnoliacom Furl Facebook

Related News Press

Chip Technology

New chip opens door to AI computing at light speed February 16th, 2024

HKUST researchers develop new integration technique for efficient coupling of III-V and silicon February 16th, 2024

Electrons screen against conductivity-killer in organic semiconductors: The discovery is the first step towards creating effective organic semiconductors, which use significantly less water and energy, and produce far less waste than their inorganic counterparts February 16th, 2024

NRL discovers two-dimensional waveguides February 16th, 2024

Discoveries

What heat can tell us about battery chemistry: using the Peltier effect to study lithium-ion cells March 8th, 2024

Researchers’ approach may protect quantum computers from attacks March 8th, 2024

High-tech 'paint' could spare patients repeated surgeries March 8th, 2024

Nanoscale CL thermometry with lanthanide-doped heavy-metal oxide in TEM March 8th, 2024

Announcements

What heat can tell us about battery chemistry: using the Peltier effect to study lithium-ion cells March 8th, 2024

Curcumin nanoemulsion is tested for treatment of intestinal inflammation: A formulation developed by Brazilian researchers proved effective in tests involving mice March 8th, 2024

The Access to Advanced Health Institute receives up to $12.7 million to develop novel nanoalum adjuvant formulation for better protection against tuberculosis and pandemic influenza March 8th, 2024

Nanoscale CL thermometry with lanthanide-doped heavy-metal oxide in TEM March 8th, 2024

NanoNews-Digest
The latest news from around the world, FREE




  Premium Products
NanoNews-Custom
Only the news you want to read!
 Learn More
NanoStrategies
Full-service, expert consulting
 Learn More











ASP
Nanotechnology Now Featured Books




NNN

The Hunger Project