Engineer shrinks 'U' logo

September 17, 2010
This electron microscope image shows a gilded University of Utah medallion -- one of several official symbols and logos for the university -- that measures only 70 microns across, which is about the diameter of a single blonde human hair. The medallion is magnified 3,000 times in this image. The gold-covered parts of the medallion appear white, while the silicon background is dark. The medallion was made using a process called electron-beam lithography. It was created by Randy Polson, a senior optical engineer at the university's Department of Physics and Astronomy, as part of his job adjusting the microscope for use by researchers and private businesses. Photo Credit: Randy Polson, The University of Utah

In an example of how a technology wonk displays school spirit, an engineer has created a golden University of Utah logo that is smaller than the width of an average human hair.

The gold etching is only 70 microns across - that's 70 millionths of a meter, or less than three one-thousandths of an inch, which is about the diameter of a blonde hair, among the thinnest types of human hair.

The etching was done on a silicon base using a thin beam of electrons from one of two electron microscopes bought by the university in 2008. While the technique of is not new, the medallion symbol is more complex than the patterns commonly made.

"People usually do things like lines and rectangles," says Randy Polson, who made the tiny medallion and is a senior optical engineer for the university's Department of Physics and Astronomy. "The software that came with the microscope included some stick-figure demos. I thought, 'Hey, I can do better than a stick figure.'"

The medallion is one of several official logos used by the university. It depicts the university's block U symbol and founding date, with a background of mountains and rays of sunshine.

It is engraved on a chip of silicon two-fifths of an inch square. To the naked eye it is a barely discernable speck. Under a conventional light microscope, it looks like a fuzzy circle. Its full detail is revealed only by a - the same device that was used to create it.

In the electron microscope image, the gold-covered parts appear white, while the silicon background appears black. The finest line on the medallion encircles the design. That line is a mere 20 thick. That's 20 billionths of a meter, or about eight ten-millionths of an inch wide. That is the length of chain of 75 gold atoms, Polson says.

Scanning electron microscopes are used most often to visualize the of objects. The microscope sends a thin beam of electrons onto the specimen, scanning back and forth over the surface.

The most common imaging mode detects "secondary electrons" released from the specimen's through reactions with the electron beam. Samples in the electron microscope that was used to create the medallion must be dry, but the department's other electron microscope can analyze wet samples - a useful feature for biological research.

Electron microscopes can create engravings using electron beam lithography because electron beams break certain large molecules into shorter chains of smaller molecules.

To create the tiny University of Utah medallion, Polson first coated the silicon chip with a thin layer of "photoresist," a polymer resin made of long chains of molecules. He then focused the electron beam on the resist surface, breaking the chains into short fragments everywhere he wanted metal to adhere.

He immersed the exposed chip in a solvent that washed away the short chains and left the long ones stuck to the silicon. Then he gilded the exposed surface - where the short chains had been removed - by placing the chip in a chamber of vaporized metal. There, nickel was deposited on the exposed silicon, and then a layer of was placed on the nickel. Polson used another solvent to wash away the remaining photoresist.

The process took about an hour. However, the bulk of the project consisted of adjusting and refining the microscope settings, part of Polson's job to make the microscope available for research. It took months for Polson to calibrate the microscope and figure out exactly what instructions to give it in order to obtain a crisp image of the university medallion.

Challenges included determining the length of time to expose the resist - too short and not enough resist washes off, too long and the image looks fuzzy - and adjusting the shape of the , which has a tendency to be elliptical instead of round.

In addition to maintaining the microscope, Polson assists university and private researchers who want to use it for a fee. People seek his help with the lithography feature for tasks such as fabricating nanowires and other components for nanoelectronics. The imaging capabilities are used in industries as diverse as pharmaceuticals and metallurgical engineering.

Explore further: Molecules could create tiny circuits on computer chips

Related Stories

Molecules could create tiny circuits on computer chips

March 16, 2010

( -- As the features on computer chips become increasingly smaller, finding ways to fabricate the chips has become a big challenge. In a new study, researchers from MIT have demonstrated that certain molecules ...

To peer inside a living cell

October 6, 2009

( -- Quantum mechanics could help build ultra-high-resolution electron microscopes that won't destroy living cells, according to MIT electrical engineers.

Experiments Prove Existence of Atomic Chain Anchors

February 3, 2005

Atoms at the ends of self-assembled atomic chains act like anchors with lower energy levels than the “links” in the chain, according to new measurements by physicists at the National Institute of Standards and Technology ...

New 'superlens' reveals hidden nanostructures

September 14, 2006

A microscope used to scan nanostructures can be dramatically enhanced by using a 'superlens,' reports an international team of scientists from the Max Planck Institute (MPI) for Biochemistry and The University of Texas at ...

PICO and SALVE: Understanding the subatomic world better

December 18, 2008

Two new high-resolution transmission electron microscopes, co-financed by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation), are set to open up new opportunities for research in physics and materials science. ...

Modified electron microscope identifies atoms

February 21, 2008

A new electron microscope recently installed in Cornell's Duffield Hall is enabling scientists for the first time to form images that uniquely identify individual atoms in a crystal and see how those atoms bond to one another. ...

Recommended for you

The microscopic origin of efficiency droop in LEDs

November 21, 2017

Light-emitting diodes—or LEDs, as they are commonly known—have been slowly replacing incandescent light bulbs in applications ranging from car taillights to indicators on electronics since their invention in the 1960s.

Borophene shines alone as 2-D plasmonic material

November 20, 2017

An atom-thick film of boron could be the first pure two-dimensional material able to emit visible and near-infrared light by activating its plasmons, according to Rice University scientists.


Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.