Experimental test chamber design for optics exposure testing and debris characterization of a xenon discharge produced plasma source for extreme ultraviolet lithography

Thompson, Keith C.; Antonsen, Erik L.; Hendricks, Matthew R.; Jurczyk, Brian E.; Williams, Michael; Ruzic, D. N.

doi:10.1016/j.mee.2005.11.012

Cited by 20 publications

(11 citation statements)

References 7 publications

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“…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.…”

Section: Experimental Exposurementioning

confidence: 99%

Optical exposure characterization and comparisons for discharge produced plasma Sn extreme ultraviolet system

Qiu

Thompson

Srivastava

et al. 2006

J. Micro/Nanolith. MEMS MOEMS

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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.

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Section: Experimental Exposurementioning

confidence: 99%

Optical exposure characterization and comparisons for discharge produced plasma Sn extreme ultraviolet system

Qiu

Thompson

Srivastava

et al. 2006

J. Micro/Nanolith. MEMS MOEMS

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“…XCEED experimental efforts are performed toward characterizing a commercial-scale DPP EUV source, including fast ion debris, debris mitigation techniques, methods to mitigate damage to collector mirrors, and exploring the characteristics and the erosive effects on the collector mirror surfaces after the DPP EUV exposures, by microanalysis measurements using atomic force microscopy ͑AFM͒, auger electron spectroscopy ͑AES͒, x-ray diffraction ͑XRD͒/x-ray reflectivity ͑XRR͒, x-ray photoelectron spectroscopy ͑XPS͒, and scanning electron microscopy ͑SEM͒ techniques. The former experiments are detailed elsewhere, 11 and the latter are presented in this paper.…”

Section: Experiments Setupmentioning

confidence: 99%

“…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.…”

Section: Introductionmentioning

confidence: 99%

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Characterization of collector optic material samples before and after exposure in laser produced plasma and discharge produced plasma extreme ultraviolet sources

Qiu

Alman

Thompson

et al. 2006

J. Micro/Nanolith. MEMS MOEMS

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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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“…1 This system is equipped with various diagnostics tools such as an electrostatic spherical sector analyzer (ESA) , a Faraday cup, and a neutral detector to detect ejected debris such as ions, neutrals, and charged particles from the Z-pinch. 2 More detailed descriptions about the working principle, calibration scheme of the ESA, and neutral detector are in our previous report. 3 A triple probe was used to detect secondary plasma formed during the pulse.…”

Section: Introductionmentioning

confidence: 99%

Measurement of particle flux at the intermediate focus of a DPP source

Sporre

Raju

Ruzic

et al. 2009

Alternative Lithographic Technologies

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The advancement of extreme ultraviolet lithography (EUVL) is shifting focus from the source to steps later in the lithographic process. Given the critical nature of preventing damage to the projection optics, source manufacturers must create clean EUV photons at the intermediate focus (IF). The same reflective surfaces that are capable of reflecting photons are also capable of reflecting potentially damaging ion and neutral debris. The Center for Plasma Material Interactions (CPMI) at the University of Illinois at ChampaignUrbana, in conjunction with SEMATECH, is developing a detector capable of measuring this debris at the intermediate focus of the source. At CPMI, we built a prototype portable, modified electrostatic spherical sector analyzer (ESA) device incorporating a neutral detector; investigated its capabilities for measuring energetic neutrals; and report results in this paper. This detector at the IF will contain a quartz crystal microbalance (QCM), Si witness plate for ex situ analysis, a set of microchannel plates (MCPs) with corresponding ion-diverting apparatus, Faraday cup as well as triple Langmuir probe. These detectors will be capable of quantifying total particle flux, neutral particle flux, and charged particle flux. To verify the capabilities of the detector, CPMI constructed a mock collector optic, which was placed inside the experimental chamber attached to CPMI's XTS 13-35 EUV source. This mock-up simulates the reflection of debris created by discharge-produced plasma (DPP), although it will not be capable of reflecting the EUV light. Recent results on the neutral, charged particle flux, and the carbon and oxygen contamination on a Si witness plate out of the line of sight of the Z-pinch are reported in this paper.

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Experimental test chamber design for optics exposure testing and debris characterization of a xenon discharge produced plasma source for extreme ultraviolet lithography

Cited by 20 publications

References 7 publications

Optical exposure characterization and comparisons for discharge produced plasma Sn extreme ultraviolet system

Optical exposure characterization and comparisons for discharge produced plasma Sn extreme ultraviolet system

Characterization of collector optic material samples before and after exposure in laser produced plasma and discharge produced plasma extreme ultraviolet sources

Measurement of particle flux at the intermediate focus of a DPP source

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