The need for a highly scalable, low debris and long lifetime source of Extreme Ultraviolet (EUV) radiation has been well established in the previous years of this conference. Presented here is Starfire Industries' basic concept of a distributed microdischarge EUV light source which emits little debris, while at the same time achieving conversion efficiencies that can be optimized to approach the theoretical physical limit of ~1.6% in a 2% band centered at 13.5nm into 2&pgr; steradians for xenon plasma. Modeling results will be presented based on a variety of techniques including: advanced magneto hydrodynamics calculations that utilize Prism Computational
Science's HELIOS-CR, an improved discharge circuit model that interfaces with and extends HELIOS-CR, and ab initio calculations of optimization of EUV collector geometry. These simulations were used together to study the variation of circuit and geometrical parameters of the Starfire microdischarge EUV source array. The results of
this parameter study suggest the optimum control conditions that will allow the production of an array of high brightness and high stability EUV sources for image transfer and high-volume lithographic manufacturing.
The University of Illinois at Urbana-Champaign (UIUC) and several national laboratories are collaborating on an effort to characterize Xe plasma source exposure effects on extreme ultraviolet (EUV) collector optics. A series of mirror samples provided by SEMATECH were exposed for 10 million shots in an Xtreme Technologies XTS 13-35 commercial EUV discharge produced plasma (DPP) source at UIUC and 500,000 shots at the high-power TRW laser produced plasma (LPP) source at Sandia National Laboratory, Livermore (SNLL). Results for both pre- and post-exposure material characterization are presented for samples exposed in both facilities. Surface analysis performed at the Center for Microanalysis of Materials at UIUC investigates mirror degradation mechanisms by measuring changes in surface roughness, texture, and grain sizes as well as analysis of implantation of energetic ions, Xe diffusion, and mixing of multilayers. Materials characterization on samples removed after varying exposure times in the XTS source identify the onset of different degradation mechanisms within each sample over 1 million to 10 million shots. Results for DPP-exposed samples for 10 million shots in the XCEED (Xtreme Commercial EUV Emission Diagnostic) experiment show that samples are eroded and that the surface is roughened with little change to the texture. Atomic force microscopy (AFM) results show an increase in roughness by a factor of 2 to 6 times, with two exceptions. This is confirmed by x-ray reflectivity (XRR) data, which shows similar roughening characteristics and also confirms the smoothening of two samples. Scanning electron microscopy (SEM) pictures showed that erosion is from 5 to 54 nm, depending on the sample material and angle of incidence for debris ions. Finally, microanalysis of the exposed samples indicates that electrode material is implanted at varying depths in the samples. The erosion mechanism is explored using a spherical energy sector analyzer (ESA) to measure fast ion species and their energy spectra...
The production of plasmas that radiate efficiently in the Soft X-Ray (SXR) or in the Extreme Ultraviolet (EUV) regions of the electromagnetic (EM) spectrum can be accomplished through laser-material interaction or via gas discharge. This paper studies the expanding plasma dynamics of ions produced from a 5J Z-pinch xenon light source used for EUV lithography. Mixed fuel experiments are performed using a mixture of Xe, N2 and H2. Energy spectra show keV-range ion energies due to the self-generated electrostatic potential created by the expanding plasma. The average energy of the expelled Xe ions is significantly decreased if the mobile lighter gas species are present to mitigate this self generated potential. The magnitude of the Xe ion signal is reduced as well. This reduction in the quantity of heavy ions and their energy could greatly extend the lifetime of the collector optics used in EUV lithography. Also the study of the dynamic evolution and spectra of plasmas is directly applicable to many projects of interest, this work will focus primary on the production of EUV radiation for nano-scale lithography. Modeling results presented here were generated using a variety of codes some developed by the Plasma Materials Interaction (PMI) group at the University of Illinois, while others, namely PrismSPECT a spectral analysis suite, were developed by Prism Computational Sciences. Presented modeling results are compared to experimental data from XTREME Commercial EUV Emission Diagnostic (XCEED) experiment at the University of Illinois.
Extreme ultraviolet (EUV) light sources are needed for next-generation lithography. A critical consideration in the development of such a source is the lifetime of collector optics. Frequent replacement of the mirror system will detract from the economic feasibility of EUV lithography. The Xtreme Commercial EUV Exposure Device (XCEED) at the University of Illinois has been designed to test the performance of various EUV mirror materials during operation of a commercial EUV source, and to investigate the mechanisms behind observed losses in reflectivity over a varying number of shots. Recently, four Mo/Si multilayer mirror samples were exposed in XCEED for variable numbers of shots, up to 40 million. The samples were analyzed to determine how the surface roughness was effected and how much material was eroded vs. time. XCEED also includes photodiodes to measure light output and light reflected from mirror samples, as well as a time-of-flight energy sector analyzer (TOF-ESA) for debris characterization. The results of these time-dependent exposures are presented in this work.
Laser produced plasmas (LPP) can be used as a source of a wide variety of useful radiation in the Soft X-ray (SXR) and Extreme Ultraviolet (EUV) spectral regime. The specific spectral range emitted depends largely on the target material. Copper, the first material studied by this group, strongly emits X-rays in the 1.0 to 1.1 nm wavelength range. These X-rays have long been used in the biological sciences. Carbon and nitrogen rich targets emit in the 2.3-4.4nm range the so called "Soft X-ray Water Window," which is extremely useful in microscopy. Tin has been shown to emit with the greatest efficiency in EUV the range around 13.5 nm which is of great industrial interest for producing semiconductors in next generation lithography machines. Here we study the processes that are required to make a LPP that will emit radiation in these spectroscopic ranges. Presentation of a model will be made that looks at the formation of plasma by looking at the physics of the laser interaction with the target, conversion efficiency, debris generation, and the processes involved in producing SXR and EUV radiation.
The University of Illinois at Urbana-Champaign (UIUC) and several national laboratories are collaborating on an SEMATECH effort to characterize xenon plasma exposure effects on EUV condenser optics. A series of mirror samples provided by SEMATECH were exposed for 10M shots in an Xtreme Technologies XTS 13-35 commercial EUV discharge plasma source at UIUC and 5M at the high-power TRW laser plasma source at Sandia National Laboratories. Results for both pre and post-exposure material characterization are presented, for samples exposed in both facilities. Surface analysis performed by the Center for Microanalysis of Materials at UIUC investigates mirror degradation mechanisms by measuring changes in surface roughness, texture, and grain sizes as well as analysis of implantation of energetic Xe ions, Xe diffusion, and mixing of multilayers. Materials characterization on samples removed after varying exposure times in the XTS source, together with in-situ EUV reflectivity measurements, identify the onset of different degradation mechanisms within each sample over 1M-100M shots. Results for DPP-exposed samples for 10 million shots in our XCEED (Xtreme Commercial EUV Exposure Device) experiment showed, in general, that samples were eroded and the surfaces were roughened with little change to the texture. AFM results showed an increase in roughness by a factor of 2-5 times, with two exceptions. This was confirmed by x-ray reflectivity (XRR) data, which showed similar roughening characteristics and also confirmed the smoothening of two samples. SEM pictures showed that erosion was from 4-47 nm, depending on the sample material and angle of incidence for debris ions. Finally, microanalysis of the exposed samples indicated that electrode material was implanted at varying depths in the samples. The erosion mechanism is explored using a spherical sector energy analyzer (ESA) to measure ion species and their energy spectra. Energy spectra for ions derived from various chamber sources are measured as a function of the Argon flow rate and angle from the centerline of the pinch. Results show creation of high energy ions (up to E = 13 keV). Species noted include ions of Xe, the buffer gas, and various electrode materials. The bulk of fast ion ejection from the pinch includes Xe+ which maximizes at ~8 keV followed by Xe2+ which maximizes at ~5 keV. Data from samples analysis and ESA measurements combined indicate mechanism and effect for debris-optic interactions and detail the effectiveness of the current debris mitigation schemes.
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