Extreme ultraviolet lithography at IMEC: Shadowing compensation and flare mitigation strategy

Lorusso, Gian; Goethals, Anne-Marie; Jonckheere, R.; Hermans, Jan; Ronse, Kurt G.; Myers, Alan M.; Kim, I.; Niroomand, Ardavan; Iwamoto, Fumio; Ritter, Daniel

doi:10.1116/1.2781516

Cited by 34 publications

(25 citation statements)

References 10 publications

(4 reference statements)

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“…The CSM results exhibited a good correlation with the CD-SEM measurements in the case of the vertical patterns (the difference in the average values was 0.3 nm); however, in the case of the horizontal patterns, the clear mask CD values measured by CSM were lower, owing to the shadowing effect. [26][27][28][29][30][31] The horizontal and vertical patterns were both measured at the best focus. Here, the horizontal-vertical (H-V) CD bias of the mask was 7.1 nm.…”

Section: Resultsmentioning

confidence: 99%

Actinic critical dimension measurement of contaminated extreme ultraviolet mask using coherent scattering microscopy

Lee

Hong

Ahn

et al. 2014

Journal of Vacuum Science &Amp; Technology B, Nanotechnology and Microelectronics: Materials, Processing, Measurement, and Phen

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The authors evaluated the feasibility of using coherent scattering microscopy (CSM) as an actinic metrology tool by employing it to determine the critical dimension (CD) and normalized image log-slope (NILS) values of contaminated extreme ultraviolet (EUV) masks. CSM was as effective as CD scanning electron microscopy (CD-SEM) in measuring the CD values of clean EUV masks in the case of vertical patterns (nonshadowing effect); however, only the CSM could detect shadowing effect for horizontal patterns resulting in smaller clear mask CD values. Owing to weak interaction between the low-density contaminant layer and EUV radiation, the CSM-based CD measurements were not as affected by contamination as were those made using CD-SEM. Furthermore, CSM could be used to determine the NILS values under illumination conditions corresponding to a high-volume manufacturing tool.

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Section: Resultsmentioning

confidence: 99%

Actinic critical dimension measurement of contaminated extreme ultraviolet mask using coherent scattering microscopy

Lee

Hong

Ahn

et al. 2014

Journal of Vacuum Science &Amp; Technology B, Nanotechnology and Microelectronics: Materials, Processing, Measurement, and Phen

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“…Optics contamination has been proven to be under control, and EUV-specific effects such as shadowing and flare, have been demonstrated to be quite predictable, hence, correctable. [7][8][9] All these factors, together with the intrinsic advantages of high resolution and extendibility, contributed to create a strong perception that EUVL is indeed happening.…”

Section: Introductionmentioning

confidence: 96%

Design correction in extreme ultraviolet lithography

Fenger

Lorusso

Hendrickx

et al. 2010

J. Micro/Nanolith. MEMS MOEMS

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Extreme ultraviolet (EUV) lithography is currently the most promising technology for advanced manufacturing nodes. This study aims to assess in detail the quality of a full chip optical correction for a EUV design, as well to discuss the available approaches to compensate for EUV-specific effects. Extensive data sets have been collected on the ASML EUV Alpha-Demo Tool using the latest Interuniversity Microelectronics Center baseline resist Shin-Etsu SEVR59. In total ∼1300 critical dimension (CD) measurements at wafer level and 700 at mask level were used as input for model calibration and validation. The smallest feature size in the data set was 32 nm. Both one-dimensional and twodimensional structures through CD and pitch were measured. The reticle used in this calibration exercise allowed one to modulate flare by varying tiling densities. The shadowing effect was modeled by means of a single bias correction throughout the design. Horizontal and vertical features of different types through pitch and CD were used to calibrate the shadowing correction. The model calibration yielded an root-mean square of ∼1 nm, which was observed to improve by including reticle CD data. An EUV mask fully corrected for optical proximity correction, flare and shadowing was fabricated and qualified, demonstrating the effectiveness of the implemented corrections. C 2010 Society of Photo-Optical Instrumentation Engineers.

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“…[1][2][3][4][5][6][7][8][9] The range of influence of flare in EUV is extremely broad ͑millimeters or more͒, thus implying that an effective full-chip compensation strategy is needed to be able to satisfy the requirements for the 32-nm node and beyond. 4,5 At the core of any strategy for flare correction is the ability to accurately and effectively calculate the local flare levels across the chip design, producing what is commonly known as a flare map.…”

Section: Introductionmentioning

confidence: 99%

“…4,5 At the core of any strategy for flare correction is the ability to accurately and effectively calculate the local flare levels across the chip design, producing what is commonly known as a flare map. [1][2][3] The calculation of flare maps in a reasonable time is not an obvious task, requiring the convolution of an extended point-spread function ͑PSF͒ at a reasonable resolution, but a great deal of progress has been made recently in this direction. 2,3 To confirm the correctness of flare calculation, the comparison to measured values is critical.…”

Section: Introductionmentioning

confidence: 99%

Flare in extreme ultraviolet lithography: metrology, out-of-band radiation, fractal point-spread function, and flare map calibration

Lorusso

Roey

Hendrickx

et al. 2009

J. Micro/Nanolith. MEMS MOEMS

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The critical role of flare in extreme ultraviolet ͑EUV͒ lithography is well known. In this work, the implementation of a robust flare metrology is discussed, and the proposed approach is qualified both in terms of precision and accuracy. The flare measurements are compared to full-chip simulations using a simplified single fractal point-spread function ͑PSF͒, and the parameters of the analytical PSF are optimized by comparing the simulation output to the experimental results. After flare map calibration, the matching of simulation and experiment in the flare range from 4 to 12% is quite good, clearly indicating an offset of about 3%. The origin of this offset is attributed to the presence of DUV light. An experimental estimate of the DUV component is found in good agreement with the predicted value.

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Extreme ultraviolet lithography at IMEC: Shadowing compensation and flare mitigation strategy

Cited by 34 publications

References 10 publications

Actinic critical dimension measurement of contaminated extreme ultraviolet mask using coherent scattering microscopy

Actinic critical dimension measurement of contaminated extreme ultraviolet mask using coherent scattering microscopy

Design correction in extreme ultraviolet lithography

Flare in extreme ultraviolet lithography: metrology, out-of-band radiation, fractal point-spread function, and flare map calibration

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