Reflectivity degradation of grazing-incident EUV mirrors by EUV exposure and carbon contamination

Shin, H.; Sporre, J.; Raju, R.; Ruzic, D. N.

doi:10.1016/j.mee.2008.10.009

Cited by 17 publications

(13 citation statements)

References 19 publications

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“…The gradual reflectivity loss was observed after the third cleaning step as well. From our previous study, the carbon contamination rate in our system is as high as 7×10 -5 nm/shot [7]. The theoretical calculation with the carbon contamination alone at the slow operation of the pinch, however, doesn't explain the observed reflectivity loss.…”

Section: Reflectivity Recovery By Sn Removal With Icp-rie Techniquementioning

confidence: 71%

“…For EUV light generation, a commercial XTS 13-35 DPP EVU system was used which is operated with 85 sccm of Xe gas in conjunction with a foil trap with 200 sccm of Ar gas as a buffer gas. Details about the XTS EUV source system can be found in the published literatures [7]. The pinch was operated with a very low frequency (10Hz) to minimize any EUV induced/assisted contamination during the measurement.…”

Section: Euv Reflectivity Recoverymentioning

confidence: 99%

“…Table 1 shows the sequence of the reflectivity measurement experiment and the description of each experiment step. Knowing that EUV exposure involves contamination in our system's cleanliness [7], the reflectivity was measured multiple times with different number of intentional exposure shots after cleaning. After each experiment step, the reflectivity was measured and normalized to the first value.…”

Section: Reflectivity Recovery By Sn Removal With Icp-rie Techniquementioning

confidence: 99%

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Remote plasma cleaning of Sn from an EUV collector mirror

Shin

Raju

Ruzic

2009

Alternative Lithographic Technologies

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Despite a higher conversion efficiency of Sn for extreme ultra violet (EUV) light generation at 13.5 nm, Sn contamination on collector optics in EUV source systems must be overcome before adopting Sn as EUV fuel. Considerable portion of debris from Sn source can be suppressed by various debris mitigation techniques. However, debris mitigation technique alone will not be sufficient for high volume manufacturing (HVM) scale light production. Sn contamination affects not only the light output but also cost of ownership because of costly and time-consuming cleaning or replacing. In order to solve this contamination issue, Center for Plasma Material Interactions (CPMI) at University of Illinois at Urbana-Champaign(UIUC) had been working on cleaning Sn from EUV collector mirror surface using inductively coupled plasma-reactive ion etching (ICP-RIE) method. Previously, our group showed the fast cleaning rate of >100±10 nm/min and the dependence of cleaning on plasma-source location. Atomic force microscopy (AFM) surface roughness scan after cleaning showed almost 95% recovery in root-mean-square roughness compared to beforecleaning. Sn debris contamination can also be cleaned by halogen gas at high pressure (several hundreds mTorr). However, cleaning rate is much slower so that longer cleaning time is needed and other components in the system can be harmed by high pressure of corrosive gas. In this study, a remote plasma cleaning method is newly investigated. We designed and fabricated a remote plasma cleaning system which operates with 13.56MHz RF. A residual gas analyzer is used to quantify the chlorine radicals generated in a remote plasma system. A comparative study on the chlorine radicals generated in ICP and remote plasma is carried out. The initial result with gas temperature control shows that more chlorine radicals generate by remote plasma than ICP. It is also reported that high power can produce more chlorine radicals as expected.

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Section: Reflectivity Recovery By Sn Removal With Icp-rie Techniquementioning

confidence: 71%

Section: Euv Reflectivity Recoverymentioning

confidence: 99%

Section: Reflectivity Recovery By Sn Removal With Icp-rie Techniquementioning

confidence: 99%

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Remote plasma cleaning of Sn from an EUV collector mirror

Shin

Raju

Ruzic

2009

Alternative Lithographic Technologies

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“…The materials used for manufacturing the EUVL mirrors must have some valuable properties, as [Shin et al, 2009], [Hecquet et al, 2007]: -manufacturing design freedom of shape and size; -sustaining of polishing procedures, up to a tenth of a nanometre for the final roughness, because the roughness became a very sensitive parameter to be considered, as the wavelength decreases; -low coefficient for thermal expansion (CTE), in order to reduce the optics distortion due to geometrical factors. There are several types of such materials, as the well known silica and quartz, or the recently developed zerodur (lithium aluminosilicate glass-ceramic) and ULE (a titania-silica binary glass with zero CTE).…”

Section: Materials For Euv Mirrorsmentioning

confidence: 99%

“…One requirement from the EUVL optics is to minimize the contamination of the Mo/Si sensible mirrors due to the debris or effluents resulted from the used components, e.g. resist, fixture materials, etc [Shin et al, 2009]. As a result, the use of any coating including carbon was dismissed for further work related to EUV mirrors [Braic et.…”

Section: Fig 8 Schematic View Of the Off-axis Optics And Vacuum Chamentioning

confidence: 99%