Nanofabrication is the design and manufacturing of devices on a scale of nanometers (1) and, as technical manager of the Pritzker Nanofabrication Facility, Peter Duda keeps the facility’s sensitive tools running, engineers improvements for the machines, and answers all undergraduate and graduate students’ questions. Mr. Duda considers working on nanofabrication as one of the best experiences for an engineer because of its tiny scale and the numerous unknowns in each individual process. Damage to even the smallest feature of a nanomaterial could be detrimental to the entire device (1). Mr. Duda comments, “Fabrication is always a great engineering challenge because you’re constantly forced to think creatively using a very large suite of tools and techniques, [to be] able to pair techniques and tools with the process that you have, as well as [to be] able to address problems that you might incur during your process.”
Undergraduate and graduate students alike wait outside Mr. Duda’s office to ask for advice or to learn more about nanofabrication techniques. This winter quarter marked the launch of the University of Chicago’s first Introduction to Nanofabrication course, which Mr. Duda teaches. The course provides an overview of techniques in nanofabrication in order to help students develop a library of skills that can be used to perform their desired work.
While Mr. Duda’s background is in optoelectronics and infrared imaging, he also worked on and installed equipment for five facilities requiring cleanrooms, including the Pritzker Nanofabrication Facility. Much of Mr. Duda’s career was in industry, and he continued his work on infrared imagery, which primarily served the aerospace industry until he started two of his own businesses. After he had sold his second business, a fabrication facility that built infrared detectors for different infrared systems, Mr. Duda worked with David Awschalom, a professor currently at the Institute of Molecular Engineering (IME), in a cleanroom at The University of California, Santa Barbara. Later, Mr. Duda saw the facility in UChicago as a great opportunity to start a major facility project at a world-class university from scratch. He combined all his previous knowledge in facility construction and equipment purchase to build the cleanroom from the ground up.
The nanofabrication facility can produce materials as small as six nanometers (1). According to Mr. Duda, ten nanometers has a resolution comparable to the taking of “the average human hair and [slicing] it ten thousand times.” Nanofabrication allows for the creation of small devices that have mechanical, optical, and fluidic applications in biology. The facility also provides a space for the IME to conduct research on quantum physics using quantum computing devices and spintronic devices. Finally, the facility is developing sensors that could be deployed to areas around the globe, such as the South Pole, in order to detect the Cosmic Microwave Background (CMB), the electromagnetic remnants of the young universe (2). Moreover, unlike most university-based fabrication facilities, the Pritzker Nanofabrication Facility also offers support in the form of expertise and excellent tools to start-up companies and to other academic institutions. Some local institutions such as Purdue, Northwestern, and The University of Illinois at Chicago, as well as non-local institutions such as Princeton, use the facility due to their respective institutions’ lack of a complete toolset for nanofabrication.
While the Pritzker Nanofabrication Facility collaborates with several universities and industries, researchers cannot simply enter the facility’s ISO Class 5 cleanroom without permission. In order to access the facility on the subfloor level, visitors must be scanned in. The cleanroom’s Class 5 standard reduces the one million particles per cubic foot in atmospheric air, filled with dust, dirt, and smoke, to less than one hundred particles per cubic foot (1). This level of cleanliness is no small feat; in fact, the ceiling is lined with high-efficiency particulate air (HEPA) filters that ventilate the entire volume of air in the room at a rate of about six to ten times a minute. “In nano-fabrication, we’re fabricating devices on a really small scale, so any dust, any dirt, any particles are enormous relative to what we’re trying to produce,” Mr. Duda says. Most of the tools used in the facility are made of semiconducting material such as those found in iPhones, computer chips, and other integrated circuits. A semiconductor can have electrical properties like those in copper while also exhibiting insulating properties like those in glass (3). The tools and sensors made from semiconductors allow the researchers to complete three main tasks: add material, create patterns, and transfer the patterns.
In order to add and remove materials, the facility must control very thin films of material exhibiting a wide range of mechanical, optical, and electrical properties. One machine can deposit films at one atomic layer at a time, creating a self-limiting process in which the thickness of the material can be controlled by the number of times the machine runs its sequence (1).
As we move further into the facility, a researcher working on a computer sits dressed in a white cleanroom gown that completely encloses his body, including gloves and masks for his feet, hair, hands, and mouth. The researcher’s dress code minimizes any extra particles he might generate himself such as dust particles clinging to clothing. This section of the facility features bright yellow lighting to block out all external UV lighting. “The predominant way that we generate patterns is through using the controlled application of light,” Mr. Duda explains. “Our tools will shine UV either through a mask that projects the image onto our substrate…or we’ll write it directly with a blue light… laser.” This photolithographic technique allows the scientists to generate patterns on the device, which are used for many purposes such as making material connections that can generate currents (1).
Another especially sensitive (and expensive) machine, generating patterns as small as six nanometers, sits alone in a room partitioned by another wall of glass. The tool uses a beam of electrons to pattern the material and is sensitive enough to electromagnetic fields to sense the L train passing by miles away from the facility (1). The protective glass wall shields the machine from Earth’s electromagnetic fields, which may affect the electron beam’s movements. The facility’s underground location provides additional screening from other vibrational and electromagnetic noise. However, quantities of certain hazardous materials important to the facility are limited due to heightened safety concerns underground, while other explosive gases travel through long piping to reach the facility because they cannot be stored underground.
For Mr. Duda, the quality of the professors and students who use the facility daily makes the nanofabrication facility and the IME at UChicago stand out. Since the facility can provide space for this tremendous increase in the quantity of students and PIs, Mr. Duda hopes that the facility’s “user base [reflects] the strength and diversity of IME and UChicago’s research in general. IME is growing and we hope that our user base grows along with that.”
(1) Duda, P. (2018, February 16). Personal interview.
(4) Cover image by VIKTOR HANACEK