Phase retrieval between overlapping orders in coherent Fourier scatterometry using scanning

Kumar, Nitish; Gawhary, Omar El; Roy, S.; Pereira, S. E.; Urbach, H. P.

doi:10.2971/jeos.2013.13048

Cited by 15 publications

(12 citation statements)

References 15 publications

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“…In this way, the angular spectrum for all scattered waves is recorded at once for all incident plane waves within the focused spot. In the event of overlapping reflected orders in the lens pupil, there is interference between them and some phase information is also registered [23]. This is achieved by scanning the grating by means of a tightly focused beam, which allows resolving the phase information in practice.…”

Section: Coherent Fourier Scatterometrymentioning

confidence: 99%

Reconstruction of sub-wavelength features and nano-positioning of gratings using coherent Fourier scatterometry

et al. 2014

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Abstract:Optical scatterometry is the state of art optical inspection technique for quality control in lithographic process. As such, any boost in its performance carries very relevant potential in semiconductor industry. Recently we have shown that coherent Fourier scatterometry (CFS) can lead to a notably improved sensitivity in the reconstruction of the geometry of printed gratings. In this work, we report on implementation of a CFS instrument, which confirms the predicted performances. The system, although currently operating at a relatively low numerical aperture (NA = 0.4) and long wavelength (633 nm) allows already the reconstruction of the grating parameters with nanometer accuracy, which is comparable to that of AFM and SEM measurements on the same sample, used as reference measurements. Additionally, 1 nm accuracy in lateral positioning has been demonstrated, corresponding to 0.08% of the pitch of the grating used in the actual experiment.

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Section: Coherent Fourier Scatterometrymentioning

confidence: 99%

Reconstruction of sub-wavelength features and nano-positioning of gratings using coherent Fourier scatterometry

et al. 2014

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“…It is the same as for coherent Fourier scatterometry experiments [4,7,12]. The light is focused by an MO to the sample.…”

Section: Principle Of Detectionmentioning

confidence: 99%

“…In case of scanning spot Fourier scatterometry [4,6,7,12,13] and interferometric Fourier scatterometry [8,14] the phase is measured between the reflected orders and with regard to a reference beam, respectively, whereas ellipsometric Fourier scatterometry measures the phase between the reflections of perpendicular polarizations. Figure 2 shows the absolute values (left graph) and phases (right graph) of the complex reflection coefficient ratios for TE and TM polarizations (equivalent with tan(Ψ) and ∆ in Eq.…”

Section: Principle Of Detectionmentioning

confidence: 99%

“…In case of the scanning spot method a coherent light source is applied, and the coherent superposition of overlapping orders is measured and calculated. The phase modulation is achieved by scanning the focused spot [6,7], [12]- [14]. Since the interference pattern measured in the far field depends on the spot position very sensitively, this method can also be used for nanopositioning, i.e.…”

Section: Comparisonmentioning

confidence: 99%

“…By using coherent illumination and a scanning focused spot, the phase can be modulated and the phase difference between the overlapping orders can be determined [4,6,7], resulting in an increase in the sensitivity as compared to phase-insensitive incoherent Fourier scatterometry. A further advantage of the coherent illumination is that the size of the focused spot is much smaller (below one micron in the visible wavelength range).…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Fourier ellipsometry – an ellipsometric approach to Fourier scatterometry

Petrik

Kumar

Fried

et al. 2015

J. Eur. Opt. Soc.-Rapid Publ.

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An extension of Fourier scatterometry is presented, aiming at increasing the sensitivity by measuring the phase difference between the reflections polarized parallel and perpendicular to the plane of incidence. The ellipsometric approach requires no additional hardware elements compared with conventional Fourier scatterometry. Furthermore, incoherent illumination is also sufficient, which enables spectroscopy using standard low-cost light sources.

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Investigation of coherent Fourier scatterometry as a calibration tool for determination of steep side wall angle and height of a nanostructure

Paul,

Rafighdoost,

Dou

et al. 2024

Meas. Sci. Technol.

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Nanostructures with steep side wall angles (swa) play a pivotal role in various technological applications. Accurate characterization of these nanostructures is crucial for optimizing their performance. In this study, we propose a far-field detection method based on coherent Fourier scatterometry (CFS) for accurate quantification of steep swa and heights in cliff-like nanostructures. Our approach introduces a parameter termed “visibility”, derived from the unique far-field signatures of cliff-like nanostructures. This parameter serves as a quantitative metric for the calibration of swa and heights. The heightened sensitivity of our method is demonstrated, particularly when the incident polarization is perpendicular to the invariant direction of the nanostructure for swa calibration, while both polarization states exhibit sensitivity to height calibration. Furthermore, a comprehensive sensitivity analysis reveals the stable nature of our method, showcasing that even with fluctuations of ±10 nm in the position of the nanostructure, the resulting swa remains stable within a range of ±0.5°. The exponential variation of the visibility parameter with edge roundness is observed, with fluctuations in edge roundness within 10 nm resulting in swa variations within 1.7° for both polarization states. In experimental validations, our results demonstrate reasonable agreement between CFS-derived and AFM measurements. The AFM data for swa (77.99° ± 1.37°) and height (148.35 nm ±2.11 nm) are corroborated with CFS-derived value of swa (77.75° ± 3.61°, 78.36° ± 3.89°) and height (149.42 nm ±1.66 nm, 150.05 nm ±1.04 nm) obtained from calibration curves for TM and TE incident beams, respectively. Overall, our findings underscore CFS as a potential and reliable tool for nanostructure characterization, offering precise measurements that are pivotal for advancing nanotechnology.

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Phase retrieval between overlapping orders in coherent Fourier scatterometry using scanning

Cited by 15 publications

References 15 publications

Reconstruction of sub-wavelength features and nano-positioning of gratings using coherent Fourier scatterometry

Reconstruction of sub-wavelength features and nano-positioning of gratings using coherent Fourier scatterometry

Fourier ellipsometry – an ellipsometric approach to Fourier scatterometry

Investigation of coherent Fourier scatterometry as a calibration tool for determination of steep side wall angle and height of a nanostructure

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