Small angle x-ray scattering measurements of lithographic patterns with sidewall roughness from vertical standing waves

Wang, Chengqing C.; Jones, Ronald L.; Lin, Eric K.; Wu, Wen‐Li; Leu, Jim

doi:10.1063/1.2737399

Cited by 55 publications

(29 citation statements)

References 8 publications

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“…Researchers at NIST have published extensively on the experimental methodology and theoretical interpretation necessary to extract relevant parameters including line width, pitch, line height, phase shift, sidewall angle, and line edge roughness, primarily based on the transmission geometry. [2][3][4] They demonstrate that the cross section shape of the lines can be inferred from the two-dimensional scattering plots of q x and q z . Figure 3 illustrates the scattering pattern which would result from a trapezoidal cross section.…”

Section: Cd-saxsmentioning

confidence: 87%

Advances in CD-Metrology (CD-SAXS, Mueller Matrix based Scatterometry, and SEM)

Thiel¹,

Cepler²,

Matyi³

et al. 2011

AIP Conference Proceedings

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Scanning Electron Microscopy (SEM) has been a mainstay of critical dimension (CD) metrology since the inception of integrated microelectronics, due to its inherent high resolution capability and relative ease of interpretation. However, as device dimensions continue to shrink, and non-planar devices become integrated into process flows (e.g., finFETs), the need to identify and develop successor technologies becomes essential. Here, we report progress on the development of two innovative technologies proposed for CD measurement, and assess their viability for high volume manufacturing applications. Finally, we describe recent efforts to extend the life of conventional CD-SEM.Small Angle X-ray Scattering (SAXS) also offers Angstrom-level resolution, is non-destructive, and requires no additional preparation steps. Performed in either transmission or reflection mode, this method is particularly suitable for arrayed structures and non-planar devices. Whereas direct imaging methods provide a complete description of a single measurement site, SAXS probes a comparatively large area containing many sites, and effectively provides information on feature dimensions and the statistical variations within the sampled. The chief limitation to implementing CD-SAXS is throughput, gated by x-ray source brilliance. Conventional x-ray tube and rotating anode sources do not have the correct combination of brightness and stability required to obtain rapid, consistent measurements. Recent innovations in x-ray source technology, including plasma and liquid metal based sources, have shown promise for making CD-SAXS a viable HVM method.Scatterometry methods offer yet another attractive approach. Advances in the optical components and simulation software enable one to obtain most of the sixteen components of the Mueller Matrix for each wavelength of light instead of the typical < and '. This is great importance when measuring highly anisotropic 3D scatterometry test structures.Finally, it is worth considering the efforts to extend the life of CD-SEM. A series of advances such as drift correct frame averaging and 3D Monte Carlo models that improve metrology for nanoscale features are all under consideration. These improvements push CD-SEM resolution closer to its theoretical limits. Additionally, the use of contrast transfer functions (CTFs) as an improved means for achieving tool matching and assessing tool performance, is considered. When an image is collected from an ideal test specimen, such as a high resolution Fresnel Zone Plate or a pseudo-random dot array, the CTF can be used as a measure of the fidelity with which specimen topography is represented in the recorded signal, as a function of spatial frequency. Tuning SEM parameters to manipulate the CTF provides a richer feedback mechanism than simply using nominal resolution and signal-to-noise ratio.

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Section: Cd-saxsmentioning

confidence: 87%

Advances in CD-Metrology (CD-SAXS, Mueller Matrix based Scatterometry, and SEM)

Thiel¹,

Cepler²,

Matyi³

et al. 2011

AIP Conference Proceedings

View full text Add to dashboard Cite

show abstract

“…In recent years, CD-SAXS studies of FinFETs, 4,5 3-D NAND structures, 5 block copolymers, 6,7 photoresists, 8 nanoimprinted gratings, [9][10][11] and grating structures with programmed line edge roughness and line width roughness [12][13][14] have shown the capability of the technique to extract the 3-D structural parameters associated with a feature's average cross section with the low-uncertainty values necessary for semiconductor line shape process monitoring. CD-SAXS is a synchrotron technique that measures the average cross section of arrays of periodic surface features through a range of incident angles in the transmission geometry.…”

Section: Introductionmentioning

confidence: 99%

Assessment of critical dimension small-angle x-ray scattering measurement approaches for FinFET fabrication process monitoring

Settens

Cordes²,

Bunday³

et al. 2014

J. Micro/Nanolith. MEMS MOEMS

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We have used synchrotron-based critical dimension small-angle x-ray scattering (CD-SAXS) to monitor the impact of hydrogen annealing on the structural characteristics of silicon FinFET structures fabricated using self-aligned double patterning on both bulk silicon and silicon-on-insulator (SOI) substrates. H 2 annealing under different conditions of temperature and gas pressure allowed us to vary the sidewall roughness and observe the response in the two metrology approaches. In the case of the simpler bulk Si FinFET structures, the CD-SAXS measurements of the critical dimensions are in substantive agreement with the top-down critical dimension scanning electron microscopy metrology. Corresponding characterizations on SOI-based FinFET structures showed less agreement, which is attributed to the more complex structural model required for SOI FinFET CD-SAXS modeling. Because sidewall roughness is an important factor in the performance characteristics of Si FinFETs, we have compared the results of roughness measurements using both critical dimension atomic force microscopy (CD-AFM) and CD-SAXS. The measurements yield similar estimates of sidewall roughness, although the CD-AFM values were typically larger than those generated by CD-SAXS. The reasons for these differences will be discussed. Downloaded From: http://nanolithography.spiedigitallibrary.org/ on 05/15/2015 Terms of Use: http://spiedl.org/terms

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“…2 Recently, we have demonstrated the capabilities of critical dimension small angle X-ray scattering (CD-SAXS) to quantify CD, pitch, line edge roughness, and cross-sectional profile in periodic line and space (i.e., grating) structures. [3][4][5][6][7][8] This technique is based on transmission small angle X-ray scattering and uses a high energy X-ray beam to pass nondestructively through silicon substrates. As the beam passes through a periodic pattern, the diffracted intensity is recorded on a two-dimensional detector (see figure 1).…”

Section: Introductionmentioning

confidence: 99%

Nonplanar high-k dielectric thickness measurements using CD-SAXS

Wang

Choi

Chen

et al. 2009

Metrology, Inspection, and Process Control for Microlithography XXIII

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Non-planar transistor architectures, such as tri-gates or "FinFETs", have evolved into important solutions to the severe challenges emerging in thermal and power efficiency requirements at the sub-32 nm technology nodes. These architectures strain traditional dimensional metrology solutions due to their complex topology, small dimensions, and number of materials. In this study, measurements of the average dielectric layer thickness are reported for a series of structures that mimic non-planar architectures. The structures are line/space patterns (≈ 20 nm linewidth) with a conformal layer of sub-15 nm thick high-k dielectric. Dimensions are measured using a transmission X-ray scattering technique, critical dimension small angle X-ray scattering (CD-SAXS). Our test results indicate that CD-SAXS can provide high precision dimensional data on average CD, pitch, and high-k dielectric layer thickness. CD-SAXS results are compared with analogous data from both top-down scanning electron microscopy and cross-sectional transmission electron microscopy. In addition, we demonstrate the capability of CD-SAXS to quantify a periodic deviation in pitch induced by an imperfection in the phase shift mask.

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Small angle x-ray scattering measurements of lithographic patterns with sidewall roughness from vertical standing waves

Cited by 55 publications

References 8 publications

Advances in CD-Metrology (CD-SAXS, Mueller Matrix based Scatterometry, and SEM)

Advances in CD-Metrology (CD-SAXS, Mueller Matrix based Scatterometry, and SEM)

Assessment of critical dimension small-angle x-ray scattering measurement approaches for FinFET fabrication process monitoring

Nonplanar high-k dielectric thickness measurements using CD-SAXS

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