About

Dren Qerimi is a Research Assistant Professor and Associate Director of the Illinois Plasma Institute at the University of Illinois Urbana-Champaign. His research trajectory in Nuclear, Plasma, and Radiological Engineering is driven by a forward-thinking approach to advancing technology and fostering collaboration between academia and industry. He is particularly engaged with the mission of the Illinois Plasma Institute, which aims to reimagine traditional pathways to technology commercialization by creating a collaborative environment where academic researchers and industrial partners can work together closely. This model facilitates the transition from laboratory research to production-level implementation, ultimately shortening the time to adoption in high-volume manufacturing. His experience within the semiconductor industry has reinforced the importance of interdisciplinary collaboration and knowledge sharing. His research interests include digital twins, EUV photo-resist development, extreme ultraviolet sources, 3-D graphene production, plasma sources such as DBD, PVD, PECVD, ICP, CCP, microwave sources, and semiconductor processing techniques like deposition and etching. His work emphasizes the development and understanding of plasma physics and fusion, with a focus on plasma sources and their applications in advanced manufacturing processes.

Research topics

• Chemistry
• Optoelectronics
• Metallurgy
• Materials science
• Optics
• Environmental chemistry
• Physics
• Nanotechnology
• Organic chemistry
• Photochemistry
• Atomic physics

Selected publications

• Thermal and irradiation disorder in porous additively manufactured 316H steel: A molecular dynamics study

  Materials Letters · 2026-02-17

  articleOpen access

  This study uses molecular dynamics simulations to examine how temperature, irradiation, and porosity influence the atomic structure of additively manufactured 316H stainless steel. The first peak of the radial distribution function g ( r ) broadens, indicating increased disorder, while the first peak of the structure factor S ( q ) intensifies, reflecting stronger short-range order. We developed an additive model that separates temperature-driven vibrational effects from irradiation- and porosity-induced static disorder, providing a clear framework to quantify damage. These results offer key insights for designing radiation-tolerant materials with engineered porosity for nuclear applications.

  PublisherDOI

• University-Scale Extreme-Ultraviolet Lithography Source

  2025-06-15

  article

  To elevate our laboratory's research capabilities in Extreme-Ultraviolet (EUV) photoresist development, we have engineered a university-scale EUV light source designed for lithography applications at a fraction of the cost of commercial EUV tools. This innovative system leverages a Nd:YAG Laser-Produced Plasma (LPP) with a swappable Tin (Sn)-based target to generate EUV radiation, offering an economical alternative to the high-cost infrastructure typically required for EUV lithography. Departing from an earlier dual EUV Multilayer Mirror (MLM) configuration, the current setup employs direct EUV exposure facilitated by a 150 nm Zirconium (Zr)-based transmission filter to isolate the EUV spectrum with high efficiency. A broad-spectrum photodiode detector, tailored to EUV wavelengths, provides accurate dosimetry, and its measurements are corroborated through successful exposure of EUV-sensitive photoresist-coated wafers. Experimental investigations have explored a range of target materials, including pure Sn and Sn doped ceramics (typically 5 at%), utilizing Spectraflux 100B (Lithium Metaborate/Lithium Tetraborate 80/20) as a foundational component. Optical Emission Spectroscopy serves as an auxiliary diagnostic tool, enabling real-time monitoring of the LPP characteristics. Optimization efforts have focused on critical parameters-laser power, beam focus, operating pressure, and target composition-to achieve precise dose control and maximize EUV output while simultaneously addressing debris mitigation, a persistent challenge in LPP systems. The results demonstrate reliable photoresist exposure with adjustable EUV dosage, positioning this system as a cost-effective yet powerful platform for academic research. Compared to multimillion-dollar commercial EUV tools, this setup provides an accessible means to explore novel EUV photoresist modifications, with ongoing projects targeting enhancements in line-edge roughness and reductions in the minimum dose required for full development. This affordable, university-scale tool thus bridges a critical gap, enabling advanced EUV lithography studies without the prohibitive expense of industrial-grade equipment.

  PublisherDOI

• Multiple distinct plasmas in extreme ultraviolet lithography sources

  Journal of Micro/Nanopatterning Materials and Metrology · 2025-09-09

  article

  To create light at 13.5±0.2 nm for extreme ultraviolet (EUV) lithography, a plasma must be created that can excite ionized species, which will radiate in that band. This can be done by a laser hitting an appropriate solid or liquid material, creating a laser-produced plasma, or by heating up such a material in a discharge-produced plasma. The desired light is produced in the first tens of nanoseconds, and then the plasma expands. We address the effects of that expansion and the plasmas produced by it. If the source chamber is filled with hydrogen gas (which is typical in EUV sources), first, the photons can produce a plasma both in the gas and by photoelectron emission on the chamber surfaces. Then, fast electrons leave the expanding plasma, which could do the same things. Finally, fast ions lead the way and again can interact with the gas or surfaces. Finally, ambipolar diffusion takes place for the remaining bulk plasma. These plasmas were measured by a triple Langmuir probe as a function of distance from the initial plasma, gas pressure, and initial plasma source gas. The experimental results are consistent with diffusion theory, taking into account the higher initial temperature of the source plasma, and with estimates of the density given knowledge about the initial plasma.

  PublisherDOI

• Evolution of graphene nanoflake size and morphology in atmospheric pressure microwave plasma

  Journal of Vacuum Science & Technology B Nanotechnology and Microelectronics Materials Processing Measurement and Phenomena · 2025-07-01 · 2 citations

  article

  Graphenelike carbon was synthesized using an atmospheric pressure microwave plasma system, employing argon/nitrogen mixtures as carrier gases and methane as the carbon precursor. This study investigates the effects of varying methane flow rates and plasma power on carbon synthesis and final morphology. The process involves the decomposition and subsequent reorganization of carbon radicals into graphene sheets and graphitic nodules. Tungsten carbide rods with attached copper collection grids were strategically positioned at three distinct points along the plasma column to collect the synthesized carbon. The variations in particle diameter were systematically analyzed using scanning electron microscopy (SEM). Results indicate that particle diameter generally increases along the plasma column, influenced heavily by plasma length. Beyond the bulk-incandescent plasma boundary, the diameter distributions remain relatively constant, suggesting that the majority of the growth occurs in the bulk and incandescent regions. Further, an increase in methane flow rate correspondingly worsened the material quality and increased the mean particle diameter across all ports, attributed to higher carbon concentrations and lower gas temperature in the plasma. Conversely, an increase in plasma power resulted in better material quality and a decrease in particle diameter at each port, which can be attributed to the rise in gas and electron temperatures increasing favorable reaction rates. Higher thermal energy accelerates the kinetic activity of carbon species in the plasma, leading to increased fragmentation of carbon precursors. This elevated energy prevents the stable aggregation of larger graphene flakes, as higher temperatures destabilize larger particle assemblies, favoring the formation of smaller graphene structures due to enhanced atomic mobility and radical-driven fragmentation. These findings demonstrate that manipulating methane flow rates and plasma power can significantly influence carbonaceous particle size, allowing for the optimization of growth conditions to achieve industry-grade graphene. This study provides a deeper understanding of the thermodynamic and chemical mechanisms governing graphene synthesis in microwave plasma systems, offering a pathway to tailored graphene production for advanced material applications.

  PublisherDOI

• Rapid Quantification of Temperatures from Molecular Emission Spectra Using the Iso-Intensity Contour Method

  SSRN Electronic Journal · 2025-01-01

  preprintOpen access
  PublisherDOI

• Investigation of stannane (SnH4) decomposition and sticking coefficient on varied metal surfaces in EUV lithography environments

  2025-02-19

  article

  Extreme ultraviolet (EUV) lithography utilizes the evaporation of tin droplets, frequently leading to the deposition of tin on various chamber surfaces. A prevalent method to remove this tin deposition involves hydrogen plasma etching, which transforms the deposited tin into stannane (SnH₄). Stannane exists in a gaseous state under operating conditions. However, is characterized by its instability, tending to decompose and adhere to various surfaces within the chamber. This investigation aims to experimentally facilitate the quantitative determination of the sticking coefficient as a function of the surface material, the temperature, and the pressure.

  PublisherDOI

• Tin removal by an annular surface wave plasma antenna in an extreme ultraviolet lithography source

  Journal of Applied Physics · 2022 · 12 citations

  1st authorCorresponding
  • Materials science
  • Chemistry
  • Optoelectronics

  Tin contamination of the collector mirror surface remains one of the crucial issues of EUV (Extreme Ultraviolet) sources, directly impacting the availability of the tool. Hydrogen plasma-based tin removal processes employ hydrogen radicals and ions to interact with tin deposits to form gaseous tin hydride (SnH4), which can be removed through pumping. An annular surface wave plasma (SWP) source developed at the University of Illinois—Urbana Champaign is integrated into the cone and perimeter of the collection mirror for in situ tin removal. The SWP is characterized by high ion and radical densities, low electron temperature, and local generation where etching is needed. This method has the potential to significantly reduce downtime and increase mirror lifetime. Radical probe measurements show hydrogen radical densities in the order of 1019 m−3, while Langmuir probe measurements show electron temperatures of up to 6 eV and plasma densities on the order of 1017–18 m−3. The generated ions are essential to the tin cleaning and have sufficiently low energy to cause no damage to the collector capping layer. Tin etch rates of up to 270 nm/min were observed in a variety of experimental conditions, including various powers, pressures, flowrates, and temperatures. The high etch rates demonstrated in this study exceed the expected contamination rate of the EUV source.

  PublisherOA PDFDOI

• Single Electrode A.C. Plasma Anemometer in High Speed H2 Jet With Background RF Plasma

  AIAA AVIATION 2022 Forum · 2022-06-20

  article

  View Video Presentation: https://doi.org/10.2514/6.2022-3364.vid Measurements in a high-speed, low pressure hydrogen jet using a cylindrical single- electrode AC-driven glow discharge flow sensor are presented. These results examine the sensitivity and voltage-current characteristics of the plasma sensor with and without the presence of a background RF plasma. These results extend the utility of the plasma sensor to a regime of rarefied, high speed gases. This sensor is being developed to fill a gap in diagnostic capabilities for use in Extreme Ultra-Violet (EUV) lithography systems that use hydrogen as a purge gas within the main vacuum chamber. The plasma sensor utilizes a high frequency (0.05-2 MHz+) AC discharge between two electrodes as the main sensing element. The voltage drop across the discharge correlates to changes in the external flow which can be calibrated for mass-flux (ρU ) or velocity. Recent experiments examine the effects of electrode geometry, AC frequency, and background ionization on the plasma sensor response. The velocity sensitivity was improved by the new electrode geometry with good response even while operating in a background plasma.

  PublisherDOI

• Tin removal by annular surface wave plasma antenna in an extreme ultraviolet source

  2022-04-22

  article1st authorCorresponding

  Tin contamination of the collector mirror surface remains one of the main issues of EUV sources, directly impacting the availability of the tool. Hydrogen plasma based tin removal processes employ hydrogen radicals and ions to interact with tin deposits to form gaseous tin hydride (SnH 4 ), which can be removed through pumping. An annular surface wave plasma (SWP) source developed at the University of Illinois – Urbana Champaign is integrated into the cone and perimeter of the collection mirror for in-situ tin removal. The SWP is characterized by high ion and radical densities, low electron temperature, and local generation where etching is needed. This method has the potential to significantly reduce downtime and increase mirror lifetime. Radical probe measurements show hydrogen radical densities in the order of 10 13 cm -3 , while Langmuir probe measurements show electron temperatures of up to 4 eV and plasma densities on the order of 10 11-12 cm -3 . The generated ions are essential to the tin cleaning and have sufficiently low energy to cause no damage to the collector capping layer. Tin etch rates of up to 250 nm/min were observed in a variety of experimental conditions, including various powers, pressures, flowrates and temperatures. The high etch rates demonstrated in this study exceed the expected contamination rate of the EUV source.

  PublisherDOI

• Radical probe system for <i>in situ</i> measurements of radical densities of hydrogen, oxygen, and nitrogen

  Journal of Vacuum Science & Technology A Vacuum Surfaces and Films · 2021 · 11 citations

  1st authorCorresponding
  • Chemistry
  • Photochemistry
  • Atomic physics

  In this study, an in situ catalytic radical probe system together with a software platform is developed to measure concentrations of reactive species in low-temperature plasmas with high spatial resolutions. The radical probes can be used to determine radical densities of hydrogen, nitrogen, and oxygen independently, in pairs and often simultaneously in any continuous plasma source in a vacuum environment. The basic principle and advantage of a probe array is the capability to distinguish between different gas species due to several sensitive elements acting as recombination catalysts. Radical densities of hydrogen, nitrogen, and oxygen were measured in a helicon plasma source. Generally, it is observed that radical densities increase with respect to pressure and power. Additionally, the electron density and electron temperature were measured by Langmuir probes. The electron density increased with increasing power and pressure. Electron temperature increased with power but decreased with increasing pressure. The key to getting absolute numbers of radical densities is based on knowing the recombination coefficient of the given gas on the catalytic surface. The probe system measures densities in a broad range of reactive species’ concentrations varying from about 1013 to 1015 cm−3.

  PublisherDOI

Frequent coauthors

• D. N. Ruzic

  University of Illinois Urbana-Champaign

  12 shared

• Gianluca A. Panici

  University of Illinois System

  9 shared

• Arihant Jain

  3 shared

• David C. Brandt

  2 shared

• Daniel Jacobson

  University of Illinois Urbana-Champaign

  2 shared

• Niels Braaksma

  2 shared

• Jack Stahl

  2 shared

• Andrew C. Herschberg

  University of Illinois System

  2 shared

Awards & honors

• Engineering Vision Award
• Nguyen Thi Coung Fellowship
• AVS Young Investigator Award