M. Hendricks

IMPACT: A facility to study the interaction of low-energy intense particle beams with dynamic heterogeneous surfaces

The Interaction of Materials with Particles and Components Testing (IMPACT) experimental facility is furnished with multiple ion sources and in situ diagnostics to study the modification of surfaces undergoing physical, chemical, and electronic changes during exposure to energetic particle beams. Ion beams with energies in the range between 20 and 5000 eV can bombard samples at flux levels in the range of 10(10)-10(15) cm(-2) s(-1); parameters such as ion angle of incidence and exposed area are also controllable during the experiment. IMPACT has diagnostics that allow full characterization of the beam, including a Faraday cup, a beam imaging system, and a retarding field energy analyzer. IMPACT is equipped with multiple diagnostics, such as electron (Auger, photoelectron) and ion scattering spectroscopies that allow different probing depths of the sample to monitor compositional changes in multicomponent and/or layered targets. A unique real-time erosion diagnostic based on a dual quartz crystal microbalance measures deposition from an eroding surface with rates smaller than 0.01 nm/s, which can be converted to a sputter yield measurement. The monitoring crystal can be rotated and placed in the target position so that the deposited material on the quartz crystal oscillator surface can be characterized without transfer outside of the vacuum chamber.

Effect of xenon bombardment on ruthenium-coated grazing incidence collector mirror lifetime for extreme ultraviolet lithography

The effect of energetic xenon ion bombardment on the extreme ultraviolet (EUV) reflectivity performance of mirrors is of vital importance for the performance of discharge- and laser-produced plasma extreme ultraviolet lithography sources. To study these effects, we measured absolute and relative reflectivities at the National Institute of Standards and Technology and the Interaction of Materials with Particles and Components Testing facility to quantify the effects of singly ionized Xe ion bombardment on the reflectivity of Ru EUV collector mirrors. Results show that unity sputtering is reached at Xe+ energies near 400–500eV. The Xe+-induced sputter yield decreases an order of magnitude with only a 60% decrease in energy. Incident angle-dependent data of Xe+ bombardment show that the sputter yield is weakly dependent on angle at energies near 1keV. Dynamic measurements of in situ EUV reflectivity during Xe+ irradiation show that the oxygen state of the reflecting mirror has a significant effect on reflect...

Effect of charged-particle bombardment on collector mirror reflectivity in EUV lithography devices

EUV metallic light radiators such as Sn or Li used for lithography will limit the lifetime of collector optics in source devices by both contamination and irradiation. Generation of EUV light requires the use of hot, dense plasma. Pinch dynamics generates fast ions and atoms, such as metallic sources (Sn, Li) with energies ranging from 100 eV up to several keV. The expanding Sn plasma will thermalize and condense in nearby components, including the debris shield and collector optics. The incident distribution of debris onto the collector optics will likely include Sn fast ions. Sn contamination will lead to two different mechanisms. One is condensation and Sn thin-film buildup on the reflective optics surface (i.e., Ru or Pd mirror) from the thermalized Sn plasma. This mechanism will lead to performance failure after about 1-2 nm build up of Sn thin film whereby the at-wavelength EUV reflectivity will decrease 20% in magnitude for grazing incident angles less than 20-degrees. The second mechanism is more complex. Fast Sn ions generated at the pinch will reach the collector optics and induce mixing, sputtering, and implant at depths between 3 and 5 monolayers on the Ru or Pd surface. EUV light can also induce ionization in background Ar or He gas used for debris mitigation. Low-energy Ar or He ions therefore impinge on the collector mirror surface at threshold-level energies between 40 and 100 eV. A steady-state Sn surface concentration will be attained after a given fluence of both Sn debris and low-energy Ar ions. The amount of Sn implanted or deposited will affect EUV reflectivity as a function of ion and/or atom fluence. Sn contamination mechanisms, as well as threshold-level sputtering from inert ion species, are studied in the IMPACT (Interaction of Materials with charged Particles and Components Testing) experiment. Sn exposure conditions include incident singly charged particles between 500 and 1000 eV, oblique incidence and incident fluxes ranging from 1011 to 1014 ions/cm2/s. In-situ surface metrology includes sputter yield diagnosis, Auger electron spectroscopy, X-ray photoelectron spectroscopy, direct recoil spectroscopy and low-energy ion scattering spectroscopy, and at-wavelength EUV reflectivity.

Debris and radiation-induced damage effects on EUV nanolithography source collector mirror optics performance

Exposure of collector mirrors facing the hot, dense pinch plasma in plasma-based EUV light sources to debris (fast ions, neutrals, off-band radiation, droplets) remains one of the highest critical issues of source component lifetime and commercial feasibility of nanolithography at 13.5-nm. Typical radiators used at 13.5-nm include Xe and Sn. Fast particles emerging from the pinch region of the lamp are known to induce serious damage to nearby collector mirrors. Candidate collector configurations include either multi-layer mirrors (MLM) or single-layer mirrors (SLM) used at grazing incidence. Studies at Argonne have focused on understanding the underlying mechanisms that hinder collector mirror performance at 13.5-nm under fast Sn or Xe exposure. This is possible by a new state-of-the-art in-situ EUV reflectometry system that measures real time relative EUV reflectivity (15-degree incidence and 13.5-nm) variation during fast particle exposure. Intense EUV light and off-band radiation is also known to contribute to mirror damage. For example offband radiation can couple to the mirror and induce heating affecting the mirrors surface properties. In addition, intense EUV light can partially photo-ionize background gas (e.g., Ar or He) used for mitigation in the source device. This can lead to local weakly ionized plasma creating a sheath and accelerating charged gas particles to the mirror surface and inducing sputtering. In this paper we study several aspects of debris and radiation-induced damage to candidate EUVL source collector optics materials. The first study concerns the use of IMD simulations to study the effect of surface roughness on EUV reflectivity. The second studies the effect of fast particles on MLM reflectivity at 13.5-nm. And lastly the third studies the effect of multiple energetic sources with thermal Sn on 13.5-nm reflectivity. These studies focus on conditions that simulate the EUVL source environment in a controlled way.

Energetic and thermal Sn interactions and their effect on EUVL source collector mirror lifetime at high temperatures

Exposure of collector mirrors facing the hot, dense pinch plasma in plasma-based EUV light sources remains one of the highest critical issues of source component lifetime and commercial feasibility of EUV lithography technology. Studies at Argonne have focused on understanding the underlying mechanisms that hinder collector mirror performance under Sn exposure and developing methods to mitigate them. Both Sn ion irradiation and thermal evaporation exposes candidate mirrors tested (i.e., Ru, Rh and Pd) in the experimental facility known as IMPACT (Interaction of Materials with charged Particles and Components Testing). Studies have led to an understanding of how Sn energetic ions compared to Sn thermal atoms affect three main surface properties of the collector mirror: 1) surface chemical state, 2) surface structure and 3) surface morphology. All these properties are crucial in understanding how collector mirrors will respond to Sn-based EUV source operation. This is primarily due to the correlation of how variation in these properties affects the reflectivity of photons in the EUV spectral range of interest (in-band 13.5-nm). This paper discusses the first property and its impact on 13.5-nm reflectivity. Investigation in the IMPACT experiment has focused on Sn thermal and energetic particle exposure on collector mirrors (Ru, Pd and Rh) and its effect on mirror performance as a function of incident thermal flux, incident ion flux, incident angle and temperature. This is possible by a new state-of-the-art in-situ EUV reflectometry system that measures real time relative EUV reflectivity at 15-degree incidence and 13.5-nm during Sn exposure. These results are then compared to at-wavelength EUV reflectivity measurements using the newly upgraded NIST-SURF facility. Sn energetic ions at 1- keV and fluxes of about 1013 cm-2s-1 are used in conjunction with a moderate flux Sn evaporative source delivering Sn fluences ranging from 1015-1017 cm-2. The temperature of the mirror sample is locally varied between 25 and 200 C with the chemical state of the surface simultaneously monitored using X-ray photoelectron spectroscopy, and lowenergy ion scattering spectroscopy. Results demonstrate the balance between energetic and thermal Sn has on the total Sn surface fraction during exposure and its effect on the structural and reflective properties of the mirror surface.

Plasma‐material Interaction Studies On Lithium And Lithiated Substrates During Compact Tokamak Operation

The role of lithium on the modification of recycling regimes in fusion reactors has renewed interest of previous lithium supershot experiments carried out in TFTR. There is a need to understand the interaction between edge plasmas and lithiated plasma‐facing components (PFCs), which have the potential of enabling fusion reactors to operate at low‐recycling regimes. The Interaction of Materials with Particles and Components Testing (IMPACT) facility at Argonne National Laboratory is currently collaborating with Princeton Plasma Physics Laboratory (PPPL) to conduct lithiated surface studies for the National Spherical Tokamak Experiment (NSTX) and the Current Drive eXperiment — Upgrade (CDX‐U). IMPACT has the necessary tools to perform experiments that diagnose the surface dynamics of lithium thin films on metallic and non‐metallic substrates, and can be monitored with multiple in‐situ techniques (LEISS, AES, QMS and XPS) capturing real‐time surface dynamics. Therefore, these techniques are available during ...

Charge breeding of radioactive isotopes at the CARIBU facility with an electron beam ion source

An Electron Beam Ion Source Charge Breeder (EBIS-CB) has been developed at Argonne National Laboratory as part of the californium rare ion breeder upgrade. For the past year, the EBIS-CB has been undergoing commissioning as part of the ATLAS accelerator complex. It has delivered both stable and radioactive beams with A/Q < 6, breeding times <30 ms, low background contamination, and charge breeding efficiencies >18% into a single charge state. The operation of this device, challenges during the commissioning phase, and future improvements will be discussed.

Effect of tin bombardment and deposition on collector mirror reflectivity in dpp euv sources

Summary form only given. The effect of Sn exposure on extreme ultraviolet (EUV) reflective properties of candidate mirror materials is a critical issue for the commercial development of EUV lithography. Studies have been carried out at the interaction of materials with particles and components testing (IMPACT), a facility dedicated to the study of interactions of materials with energetic ions. Equipped with multiple in-situ diagnostics for interrogating the surface, information can be obtained from the sample being treated in real time, capturing dynamic effects that can not be observed with ex-situ measurements. The effect of Xe bombardment on the EUV reflectivity response of both single layer and multilayer mirrors has been studied in this facility, giving important insights regarding optics lifetime during EUV source operation. Two types of Sn exposures were performed in IMPACT: exposure to a thermal source and to an energetic source. The thermal source simulates the effect expected due to vapor condensation, while the energetic source simulates bombardment due to energetic ions coming from the pinch. The results obtained for the case of deposited Sn have confirmed previous knowledge about the behavior of EUV optics with Sn overlayers, which lead to a significant reflectivity loss. The case of energetic Sn bombardment has not been studied extensively. It is inherently different from Xe bombardment, since Sn can be assimilated by the sample, while Xe simply escapes provided the fluence is low. Mirrors subject to bombardment at different energies and angles show a saturation effect, also predicted by dynamic Monte Carlo computer simulations of the implantation. This saturation is a consequence of both Sn-induced mixing and sputtering. In-situ surface diagnostics include low-energy ion scattering spectroscopy (LEISS) and X-ray photoelectron spectroscopy (XPS) conducted in real time during Sn-ion irradiation. In addition, a new in-situ EUV real-time reflectometer that uses a Si target-based photon source at 15 degrees incident with respect to the mirror surface has been installed in IMPACT. Ex-situ diagnosis includes: X-ray reflectivity, electron microscopy and atomic force microscopy