On a regular basis, David Vellenga helps scientists from across the nation operate multimillion dollar equipment for research projects whose details he isn’t even allowed to know about. Sensitive trade secrets and proprietary information are just a part of his job. Furthermore, everything Vellenga does at work is on a nanoscale level, about a million times smaller than the size of a pinhead.
Some might assume that a job this interesting could only be found in a top-secret government agency or underground laboratory. But in fact, David Vellenga works right here in our state, at the Triangle National Lithography Center (TNLC) at North Carolina State University.
This state-of-the-art, multi-million dollar facility, jointly founded by UNC Chapel Hill and NC State, is one of thirteen public user laboratories that make up the National Nanotechnology Infrastructure Network. This organizational network coordinates research and development efforts in nanotechnology across the United States, and the TNLC is “just one part of this much larger picture,” says Vellenga.
The TLNC is home to a 193-nanometer scanner lithography tool, the premier tool for advanced optical lithography in the nation. Optical lithography is a process used to create microelectronic circuits and optical devices on the nanoscale level.
Optical lithography, even on such a small scale, is similar to the process of photography, in which a chemical reaction involving light changes film, exposing pictures and images. The difference is that optical lithography images are not printed on photo paper, but on silicon wafers covered with a thin photo-sensitive film. Instead of typical 4x6 inch snapshots, these wafers are round disks about a millimeter thick and 6 to 12 inches in diameter, depending on the exposure tool used.
The scanner can fill the surface of these wafers with images typically 2 or 3 millimeters square. In turn, these images are made up of very small features, some of which are only tens of nanometers in size. This is incredibly small, considering that one nanometer is only about 1 one-hundred-thousandth of the width of a human hair.
The first step in optical lithography is the creation of a reticle, a glass and chrome template of the pattern that is to be transcribed. When light shines through the reticle onto the silicon wafer, the image is projected four times smaller and printed on the wafer surface. The image is then developed in a base solution, in order to dissolve away all of the areas where the light hit the film, and leave the pattern intact.
Depending on what they are creating, researchers may then use another tool to etch away the areas where the light hit the wafer. Repeating this lithography cycle over and over is one way to produce semiconductor chips and other very small objects with multiple layers of patterns, or circuits.
While there are older generations of optical lithography tools available for use elsewhere in the nation, NC State’s is one of the newest and most advanced versions, with very high resolution. The 193-nanometer tool allows patterning on the smallest scale currently possible. Just like in photography, resolution is important. In semiconductor lithography, resolution refers to the ability to write very small patterns on very small nanodevices and nanostructures.
There is a constant effort to develop new lithography tools with the capability to pattern smaller and smaller features on even smaller objects. Carlton Osburn, director of the TNLC, relates the evolution of lithography to Moore’s Law.
Moore’s Law is the prediction made by Gordon Moore, the co-founder of Intel, that computer processing power, measured by the number of transistors that could fit on an integrated circuit, would double every 18 months. So far, this law has held true. But it is unlikely to continue to hold true without the help of state-of-the-art devices like NC State’s lithography tool, which make it possible for researchers to continue creating these integrated circuits with smaller and smaller features and more and more processing power.
Optical lithography is not the only process that can be used to create nanoscale devices. E-beam lithography devices, which use electron beams instead of light to write patterns, can actually write smaller patterns than NC State’s equipment can. But because optical lithography is a faster process and has the ability to write a large number of patterns over a large area of film, it is often more useful for industrial research and production. The 193-nanometer lithography tool at NC State is not only one of the most advanced tools used for this purpose, it is the only one available for public use in the United States.
That makes the TNLC’s public user facility a very attractive site for researchers in both the public and private sector. According to Osburn, this optical lithography tool has become the “industrial workhorse of the semiconductor industry.”
Osburn estimates that about 70% of the projects being done at the Center are industrial projects, and that the other 30% are university projects.
Both the university and industrial research efforts at TNLC will generate new products and innovations in the years to come. Photonic devices designed for communication applications, nano-scale particles for use in enhanced drug delivery, and high-performance, low-cost nanowire based semiconductor devices are a few examples of current projects.
This state-of-the-art facility is an important economic resource for the area, and puts Raleigh, North Carolina among the top nanotechnology research centers in the nation.
“Where the new jobs will be concentrated for the emerging nanotech world will be where the infrastructure is available to support economic development. The past vision where companies were started in people’s garages won’t apply to nanotechnology because the tools and infrastructure to work at the nano-scale are very expensive,” says Joe DeSimone, director of the NSF Science and Technology Center at UNC. He was instrumental in initially convincing NC State and UNC to purchase the optical lithography tool, and his research group often travels to NC State to do research at the facility.
“The universities’ vision to invest in nanotechnology, through the formation of the TNLC and Carolina’s investment to start the Institute for Advanced Materials, Nanotechnology and Science is critical for the RTP region to be a powerhouse in the creation of new jobs related to this burgeoning field,” DeSimone adds. As someone who often does research of his own at this facility, DeSimone understands the value of TNLC, and the economic opportunities it creates in our state.
Those opportunities will help expand and strengthen sectors such as information technology, communication services, and software development – all of which are vital to North Carolina’s 21st century economy.
By Kate McDonald
Originally from Davidson, North Carolina, Kate is currently a senior majoring in public policy at the University of North Carolina at Chapel Hill. As part of her public policy studies, she is performing an internship for the Office of Science and Technology in the North Carolina Department of Commerce.
