The influence of line edge roughness and CD uniformity on EUV scatterometry for CD characterization of EUV masks

Scholze, Frank; Laubis, Christian; Dersch, U.; Pomplun, Jan; Burger, Sven; Schmidt, Frank

doi:10.1117/12.726159

Cited by 23 publications

(24 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…If there is not enough angular range available to observe the interference fringes, the same measurement could be done at fixed angle with varying wavelength. On EUV masks, reflectometry allows to measure the silicon capping and oxide layer thickness in open fields at the mask and also to measure the total height of the absorber stack above the multilayer as shown elsewhere 8 . Parameters like the height of the absorber lines can therefore be measured independently 8 .…”

Section: Reflectometrymentioning

confidence: 99%

Use of EUV scatterometry for the characterization of line profiles and line roughness on photomasks

Scholze

Laubis

2008

SPIE Proceedings

Self Cite

View full text Add to dashboard Cite

Scatterometry is a versatile metrology for characterizing periodic structures, regarding critical dimension (CD) and other profile properties. With respect to small feature sizes on future lithography photomasks, the short wavelength of extreme ultraviolet (EUV) radiation is advantageous since it minimizes diffraction phenomena and increases the sensitivity to roughness. The advantage of the short wavelength can also be used for investigations of DUV photomasks. For EUV masks, only EUV radiation provides direct information on at-wavelength mask performance. The intensity of the measured diffraction orders carries information about the absorber line profile like top CD, sidewall angle, height, and top corner radius. It is shown that it is feasible to derive information on the absorber line profile in periodic areas of lines and spaces by means of rigorous numerical modeling with the finite element method (FEM). We demonstrate the determination of line profile parameters for chrome on glass (CoG) and EUV masks. EUV Reflectometry on CoG masks is successfully used to determine absorber line heights. A good correlation (0.2 nm rms) between CD values determined using EUV scatterometry and CD-SEM is demonstrated for an EUV mask. A clear correlation between diffuse scatter intensity and CD uniformity, respectively line roughness, is also obtained.

show abstract

Section: Reflectometrymentioning

confidence: 99%

Use of EUV scatterometry for the characterization of line profiles and line roughness on photomasks

Scholze

Laubis

2008

SPIE Proceedings

Self Cite

View full text Add to dashboard Cite

show abstract

“…Previously the solver has been used in scatterometric investigations of EUV line masks with 2D and 3D periodic absorber structures. 3,8,9 Recently we have reported on rigorous electromagnetic field simulations of 3D-periodic arrays of absorber structures on EUV masks. 10 This report contains a sensitivity study for horizontal and vertical scatterometry, focusing on the side wall angle for grating structures.…”

Section: Horizontal and Vertical Scatterometrymentioning

confidence: 99%

Scatterometry sensitivity analysis for conical diffraction versus in-plane diffraction geometry with respect to the side wall angle

2013

Self Cite

View full text Add to dashboard Cite

Extreme UV scatterometry using radiation in the extreme ultraviolet photon energy range, with wavelengths around 13.5 nm, provides direct information on the performance of EUV optical components, e.g. EUV photomasks, in their working wavelength regime. Scatterometry with horizontal diffraction geometry, parallel to the grating lines (conical), and vertical scattering geometry, perpendicular to the lines (in-plane), was performed on EUV lithography mask test structures. Numerical FEM based simulations, using a rigorous Maxwell solver, compare both experimental set-ups with focus on the sensitivity of the diffraction intensities particularly with respect to the side wall angle.

show abstract

“…LER and structure position deviations will significantly affect the diffraction patterns measured in scatterometry 30 . As scatterometry is widely applied for in-line measurements for process control in the semiconductor industry, it is very important to accurately measure the LER and the structure position deviation, and to study their influence on scatterometric measurements.…”

Section: Ler and Lwrmentioning

confidence: 99%

“…The x-and y-grating patterns in different dies have different nominal CDs (90 nm to 500 nm) and different line/space ratios (1:20 to 20:1). A detailed description of the mask architecture can be found in 30 . The mask layer structure is shown schematically in Figure 3.…”

Section: Scatterometrymentioning

confidence: 99%

Comparison of CD measurements of an EUV photomask by EUV scatterometry and CD-AFM

et al. 2013

Self Cite

View full text Add to dashboard Cite

EUV scatterometry is a potential high-throughput measurement method for the characterization of EUV photomask structures. We present a comparison of angle resolved extreme ultraviolet (EUV) scatterometry and critical dimension atomic force microscope (CD-AFM) as a reference metrology for measurements of geometrical parameters like line width (CD), height and sidewall angle of EUV photomask structures. The structures investigated are dense and semidense bright and dark lines with different nominal CDs between 140 nm and 540 nm. The results show excellent linearity of the critical dimension measured with both methods within a range of only 1.8 nm and an offset of the absolute values below 3 nm. A maximum likelihood estimation (MLE) method is used to reconstruct the shape parameters and to estimate their uncertainties from the measured scattering efficiencies. The newly developed CD-AFM at PTB allows versatile measurements of parameters such as height, CD, sidewall angle, line edge/width roughness, corner rounding, and pitch. It applies flared tips to probe steep and even undercut sidewalls and employs a new vector approaching probing (VAP) strategy which enables very low tip wear and high measurement flexibility. Its traceability is ensured by a set of calibrated step-height and reference CD standards.

show abstract

The influence of line edge roughness and CD uniformity on EUV scatterometry for CD characterization of EUV masks

Cited by 23 publications

References 0 publications

Use of EUV scatterometry for the characterization of line profiles and line roughness on photomasks

Use of EUV scatterometry for the characterization of line profiles and line roughness on photomasks

Scatterometry sensitivity analysis for conical diffraction versus in-plane diffraction geometry with respect to the side wall angle

Comparison of CD measurements of an EUV photomask by EUV scatterometry and CD-AFM

Contact Info

Product

Resources

About