Abstract:The XCEED chamber was designed to allow diagnostic access to the conditions experienced by collecting optics for a discharge produced plasma (DPP) source. The chamber provides access for EUV photodiodes, sample exposure tests, Faraday cup measurements, and characterization of the ion debris field by a spherical sector energy analyzer (ESA). The Extreme Ultraviolet (EUV) light source creates a xenon z-pinch for the generation of 13.5 nm light. Typical EUV emission is characterized though a control photodiode. T… Show more
“…The study explores the erosive effects on the collector mirror surfaces after the DPP EUV exposures, by microanalysis measurements using atomic force microscopy (AFM), auger electron spectroscopy (AES), and scanning electron microscopy (SEM) techniques. The former experiments are detailed elsewhere [4][5] , and the latter are presented in detail in the present manuscript. The XCEED utilizes a XTS 13-35 source which has recently been upgraded to an optimized source frequency to produce EUV light from Sn ions.…”
A critical issue for EUVL is the minimization of collector degradation from intense plasma erosion, debris deposition and hydrocarbon/oxide contamination. Collector optics reflectivity and lifetime heavily depends on surface chemistry and interactions between fuels and various mirror materials, such as silicon, in addition to high-energy ion and neutral particle erosion effects. As a continuation of our prior investigation of DPP and LPP Xe plasma interactions with collector optics surfaces, the University of Illinois has analyzed collector samples before and after exposure in a Sn-upgraded Xtreme Technologies EUV source. Sn DPP post-exposure characterization includes multiple samples, Si/Mo multilayer film with normal incidence, 200 nm thick Ru film with grazing incidence, as well as a Gibbsian segregated (GS) Mo-Au alloy developed on silicon using a DC dualmagnetron co-sputtering system at UIUC. Pre and post exposed sample characterization studies actually investigates the surface roughness properties, erosion resistance and self-healing characteristics to maintain reflectivity over a longer period of mirror lifetime. Surface analysis draws heavily on the expertise of the Center for Microanalysis of Materials at UIUC, and investigates mirror degradation mechanisms by measuring changes in surface roughness, texture, and grain sizes as well as analysis of the implantation of energetic Sn ions, Sn diffusion, and mixing of multi-layers. Results from atomic force microscopy (AFM) and auger electron spectroscopy (AES) measurements show exposure effects on surface roughness and contamination. The best estimates of thickness and the resultant erosion measurements are obtained from scanning electron microscopy (SEM). Implantation, diffusion, and mixing effects are analyzed with depth profiles using AES. Materials characterization on samples, removed after varying exposure times in the XTS source, together with in-situ EUV reflectivity measurements, can identify the onset of different degradation mechanisms within each sample. These samples are the first fully characterized materials to be exposed to a Sn-based DPP EUV source. Several valuable and interesting facts were noticed. First, hot mirrors exposed to SnCl 4 will cause decomposition of the gas and will result into a contamination layer build up on the mirror surface. Secondly, erosion is mitigated to some extent by the simultaneous deposition of material. Third and most important is that the Gibbsian segregation concept works and a thin Au layer is maintained during the entire exposure, even though overall erosion took place. This phenomenon could be very useful in the design and development of a collector optics surface. In addition, this paper will present Sn DPP collector erosion mechanisms, source debris spectra and provide insight into plasma-facing optics lifetime as HVM tool conditions are approached.
“…The study explores the erosive effects on the collector mirror surfaces after the DPP EUV exposures, by microanalysis measurements using atomic force microscopy (AFM), auger electron spectroscopy (AES), and scanning electron microscopy (SEM) techniques. The former experiments are detailed elsewhere [4][5] , and the latter are presented in detail in the present manuscript. The XCEED utilizes a XTS 13-35 source which has recently been upgraded to an optimized source frequency to produce EUV light from Sn ions.…”
A critical issue for EUVL is the minimization of collector degradation from intense plasma erosion, debris deposition and hydrocarbon/oxide contamination. Collector optics reflectivity and lifetime heavily depends on surface chemistry and interactions between fuels and various mirror materials, such as silicon, in addition to high-energy ion and neutral particle erosion effects. As a continuation of our prior investigation of DPP and LPP Xe plasma interactions with collector optics surfaces, the University of Illinois has analyzed collector samples before and after exposure in a Sn-upgraded Xtreme Technologies EUV source. Sn DPP post-exposure characterization includes multiple samples, Si/Mo multilayer film with normal incidence, 200 nm thick Ru film with grazing incidence, as well as a Gibbsian segregated (GS) Mo-Au alloy developed on silicon using a DC dualmagnetron co-sputtering system at UIUC. Pre and post exposed sample characterization studies actually investigates the surface roughness properties, erosion resistance and self-healing characteristics to maintain reflectivity over a longer period of mirror lifetime. Surface analysis draws heavily on the expertise of the Center for Microanalysis of Materials at UIUC, and investigates mirror degradation mechanisms by measuring changes in surface roughness, texture, and grain sizes as well as analysis of the implantation of energetic Sn ions, Sn diffusion, and mixing of multi-layers. Results from atomic force microscopy (AFM) and auger electron spectroscopy (AES) measurements show exposure effects on surface roughness and contamination. The best estimates of thickness and the resultant erosion measurements are obtained from scanning electron microscopy (SEM). Implantation, diffusion, and mixing effects are analyzed with depth profiles using AES. Materials characterization on samples, removed after varying exposure times in the XTS source, together with in-situ EUV reflectivity measurements, can identify the onset of different degradation mechanisms within each sample. These samples are the first fully characterized materials to be exposed to a Sn-based DPP EUV source. Several valuable and interesting facts were noticed. First, hot mirrors exposed to SnCl 4 will cause decomposition of the gas and will result into a contamination layer build up on the mirror surface. Secondly, erosion is mitigated to some extent by the simultaneous deposition of material. Third and most important is that the Gibbsian segregation concept works and a thin Au layer is maintained during the entire exposure, even though overall erosion took place. This phenomenon could be very useful in the design and development of a collector optics surface. In addition, this paper will present Sn DPP collector erosion mechanisms, source debris spectra and provide insight into plasma-facing optics lifetime as HVM tool conditions are approached.
“…The samples were characterized by microanalysis measurements using atomic force microscopy ͑AFM͒, auger electron spectroscopy ͑AES͒, and scanning electron microscopy ͑SEM͒ techniques. The former experiments are detailed elsewhere, [13][14][15] and the latter are presented in this paper.…”
A critical issue for EUV lithography ͑EUVL͒ is the minimization of collector degradation from intense plasma erosion, debris deposition, and hydrocarbon/oxide contamination. Collector optics reflectivity and lifetime heavily depend on surface chemistry and interactions between fuels and various mirror materials, such as silicon, in addition to highenergy ion and neutral particle erosion effects. As a continuation of our prior investigations of discharge-produced plasma ͑DPP͒ and laserproduced plasma ͑LPP͒ Xe plasma interactions with collector optics surfaces, the University of Illinois at Urbana-Champaign ͑UIUC͒ has analyzed collector samples before and after exposure in a Sn-upgraded Xtreme Technologies EUV source. Sn DPP postexposure characterization includes multiple samples, Si/ Mo multilayer film with normal incidence, 200-nm-thick Ru film with grazing incidence, as well as a Gibbsian segregated ͑GS͒ Mo-Au alloy developed on silicon using a dc dualmagnetron cosputtering system at UIUC for enhanced surface roughness properties, erosion resistance, and self-healing characteristics to maintain reflectivity over a longer period of mirror lifetime. Surface analysis draws heavily on the expertise of the Center for Microanalysis of Materials at UIUC, and investigates mirror degradation mechanisms by measuring changes in surface roughness and film thickness as well as analysis of deposition of energetic Sn ions, Sn diffusion, and mixing of multilayer. Results from atomic force microscopy ͑AFM͒ and auger electron spectroscopy ͑AES͒ measurements show exposure effects on surface roughness and contamination. The best estimates of thickness and the resultant erosion measurements are obtained from scanning electron microscopy ͑SEM͒. Deposition, diffusion, and mixing effects are analyzed with depth profiles by AES. Material characterization on samples removed after varying exposure times in the XTS source can identify the onset of different degradation mechanisms within each sample. These samples are the first fully characterized materials to be exposed to a Sn-based DPP EUV source. Several valuable lessons are learned. First, hot mirrors exposed to SnCl 4 gas will cause decomposition of the gas and build up a contamination layer on the surface. Second, erosion is mitigated to some extent by the simultaneous deposition of material. Third, and most important, Gibbsian segregation works and a thin Au layer is maintained during exposure, even though overall erosion is taking place. This phenomenon could be very useful in the design of a collector optics surface. In addition, we present Sn DPP collector erosion mechanisms and contamination and provide insight into plasma-facing optics lifetime as high-volume manufacturing ͑HVM͒ tool conditions are approached.
“…The chamber allows characterization of optic samples at varying exposure times for normal and grazing incidence reflection angles. [9][10][11] All DPP mirror samples discussed here are placed 56 cm from pinch and exposed for 10 million pulses ͑ϳ11 h exposure͒ with debris mitigation present. Au, C, Mo, Si, and ML1 are exposed at normal incidence ͑mirror plane is ϳ80 deg to the incoming light vector͒, while Pd and Ru are exposed at ϳ 20-deg grazing incidence.…”
Section: Experiments Setupmentioning
confidence: 99%
“…This paper covers the comparative surface analysis between optically exposed samples at the Sandia National Laboratory, Livermore, ͑SNLL͒ laser produced plasma ͑LPP͒ experimental facility 6,7 and the UIUC discharge produced plasma ͑DPP͒ experimental facility. [8][9][10][11] Film with a high reflectivity at 13.5 nm ͑the wavelength to be used for EUV lithography͒ and a high durability against erosion is needed to be the collector mirror in EUV applications. Based on the preceding criteria, seven samples are investigated consisting of one Si/ Mo multilayer mirror ͑MLM͒ and six single material films of thickness ϳ200 nm deposited on Si substrates.…”
The University of Illinois at Urbana-Champaign ͑UIUC͒ and several national laboratories are collaborating on an effort to characterize Xe plasma source exposure effects on extreme ultraviolet ͑EUV͒ 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 ͑DPP͒ source at UIUC and 500,000 shots at the high-power TRW laser produced plasma ͑LPP͒ source at Sandia National Laboratory, Livermore ͑SNLL͒. 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 Diagnostic͒ experiment show that samples are eroded and that the surface is roughened with little change to the texture. Atomic force microscopy ͑AFM͒ results show an increase in roughness by a factor of 2 to 6 times, with two exceptions. This is confirmed by x-ray reflectivity ͑XRR͒ data, which shows similar roughening characteristics and also confirms the smoothening of two samples. Scanning electron microscopy ͑SEM͒ 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 ͑ESA͒ to measure fast 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 highenergy ions ͑up to E = 13 keV͒. Species noted include ions of Xe, Ar ͑a buffer gas͒, and various materials from the electrodes and debris tool. The bulk of fast ion ejection from the pinch includes Xe + , which maximizes at ϳ8 keV, followed by Xe 2+ , which maximizes at ϳ5 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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