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Title: Characterization of the shape and line-edge roughness of polymer gratings with grazing incidence small-angle X-ray scattering and atomic force microscopy

Abstract

Grazing-incidence small-angle X-ray scattering (GISAXS) is increasingly used for the metrology of substrate-supported nanoscale features and nanostructured films. In the case of line gratings, where long objects are arranged with a nanoscale periodicity perpendicular to the beam, a series of characteristic spots of high-intensity (grating truncation rods, GTRs) are recorded on a two-dimensional detector. The intensity of the GTRs is modulated by the three-dimensional shape and arrangement of the lines. Previous studies aimed to extract an average cross-sectional profile of the gratings, attributing intensity loss at GTRs to sample imperfections. Such imperfections are just as important as the average shape when employing soft polymer gratings which display significant line-edge roughness. Herein are reported a series of GISAXS measurements of polymer line gratings over a range of incident angles. Both an average shape and fluctuations contributing to the intensity in between the GTRs are extracted. Lastly, the results are critically compared with atomic force microscopy (AFM) measurements, and it is found that the two methods are in good agreement if appropriate corrections for scattering from the substrate (GISAXS) and contributions from the probe shape (AFM) are accounted for.

Authors:
 [1];  [2];  [3];  [4];  [4];  [4];  [1];  [3];  [1];  [1];  [1];  [1]
  1. Univ. of Chicago, Chicago, IL (United States); Argonne National Lab. (ANL), Argonne, IL (United States)
  2. Univ. of Chicago, Chicago, IL (United States)
  3. IMEC, Leuven (Belgium)
  4. Argonne National Lab. (ANL), Argonne, IL (United States)
Publication Date:
Research Org.:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22). Materials Sciences and Engineering Division
OSTI Identifier:
1267149
Grant/Contract Number:
AC02-06CH11357
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Journal of Applied Crystallography (Online)
Additional Journal Information:
Journal Name: Journal of Applied Crystallography (Online); Journal Volume: 49; Journal Issue: 3; Journal ID: ISSN 1600-5767
Publisher:
International Union of Crystallography
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; grazing-incidence small-angle X-ray scattering; GISAXS; polymer gratings; line-edge roughness; grating truncation rods

Citation Formats

Suh, Hyo Seon, Chen, Xuanxuan, Rincon-Delgadillo, Paulina A., Jiang, Zhang, Strzalka, Joseph, Wang, Jin, Chen, Wei, Gronheid, Roel, de Pablo, Juan J., Ferrier, Nicola, Doxastakis, Manolis, and Nealey, Paul F.. Characterization of the shape and line-edge roughness of polymer gratings with grazing incidence small-angle X-ray scattering and atomic force microscopy. United States: N. p., 2016. Web. doi:10.1107/S1600576716004453.
Suh, Hyo Seon, Chen, Xuanxuan, Rincon-Delgadillo, Paulina A., Jiang, Zhang, Strzalka, Joseph, Wang, Jin, Chen, Wei, Gronheid, Roel, de Pablo, Juan J., Ferrier, Nicola, Doxastakis, Manolis, & Nealey, Paul F.. Characterization of the shape and line-edge roughness of polymer gratings with grazing incidence small-angle X-ray scattering and atomic force microscopy. United States. doi:10.1107/S1600576716004453.
Suh, Hyo Seon, Chen, Xuanxuan, Rincon-Delgadillo, Paulina A., Jiang, Zhang, Strzalka, Joseph, Wang, Jin, Chen, Wei, Gronheid, Roel, de Pablo, Juan J., Ferrier, Nicola, Doxastakis, Manolis, and Nealey, Paul F.. Fri . "Characterization of the shape and line-edge roughness of polymer gratings with grazing incidence small-angle X-ray scattering and atomic force microscopy". United States. doi:10.1107/S1600576716004453. https://www.osti.gov/servlets/purl/1267149.
@article{osti_1267149,
title = {Characterization of the shape and line-edge roughness of polymer gratings with grazing incidence small-angle X-ray scattering and atomic force microscopy},
author = {Suh, Hyo Seon and Chen, Xuanxuan and Rincon-Delgadillo, Paulina A. and Jiang, Zhang and Strzalka, Joseph and Wang, Jin and Chen, Wei and Gronheid, Roel and de Pablo, Juan J. and Ferrier, Nicola and Doxastakis, Manolis and Nealey, Paul F.},
abstractNote = {Grazing-incidence small-angle X-ray scattering (GISAXS) is increasingly used for the metrology of substrate-supported nanoscale features and nanostructured films. In the case of line gratings, where long objects are arranged with a nanoscale periodicity perpendicular to the beam, a series of characteristic spots of high-intensity (grating truncation rods, GTRs) are recorded on a two-dimensional detector. The intensity of the GTRs is modulated by the three-dimensional shape and arrangement of the lines. Previous studies aimed to extract an average cross-sectional profile of the gratings, attributing intensity loss at GTRs to sample imperfections. Such imperfections are just as important as the average shape when employing soft polymer gratings which display significant line-edge roughness. Herein are reported a series of GISAXS measurements of polymer line gratings over a range of incident angles. Both an average shape and fluctuations contributing to the intensity in between the GTRs are extracted. Lastly, the results are critically compared with atomic force microscopy (AFM) measurements, and it is found that the two methods are in good agreement if appropriate corrections for scattering from the substrate (GISAXS) and contributions from the probe shape (AFM) are accounted for.},
doi = {10.1107/S1600576716004453},
journal = {Journal of Applied Crystallography (Online)},
number = 3,
volume = 49,
place = {United States},
year = {Fri Apr 22 00:00:00 EDT 2016},
month = {Fri Apr 22 00:00:00 EDT 2016}
}

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  • The need to characterize line edge and line width roughness in patterns with sub-50 nm critical dimensions challenges existing platforms based on electron microscopy and optical scatterometry. The development of x-ray based metrology platforms provides a potential route to characterize a variety of parameters related to line edge roughness by analyzing the diffracted intensity from a periodic array of test patterns. In this study, data from a series of photoresist line/space patterns featuring programmed line width roughness are measured by critical dimension small angle x-ray scattering (CD-SAXS). For samples with designed periodic roughness, CD-SAXS provides the wavelength and amplitude ofmore » the periodic roughness through satellite diffraction peaks. For real world applications, the rate of decay of intensity, termed an effective 'Debye-Waller' factor in CD-SAXS, provides an overall measure of the defects of the patterns. CD-SAXS data are compared to values obtained from critical dimension scanning electron microscopy (CD-SEM). Correlations between the techniques exist, however significant differences are observed for the current samples. A tapered cross sectional profile provides a likely explanation for the observed differences between CD-SEM and CD-SAXS measurements.« less
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  • New results are presented for the annealing behavior of ultrathin complementary-metal-oxide-semiconductor (CMOS) gate dielectric HfO{sub 2} films grown by atomic layer deposition (ALD). A series of ALD HfO{sub 2} dielectric films has been studied by a combination of x-ray reflectivity (XRR) and grazing-incidence small-angle x-ray scattering (GISAXS) measurements. By using these techniques together, we have shown that the surface, interfaces, and internal structure of thin ALD films can be characterized with unprecedented sensitivity. Changes in film thickness, film roughness, or diffuseness of the film/substrate interface as measured by XRR are correlated with the corresponding changes in the internal film nanostructure,more » as measured by GISAXS. Although the films are dense, an internal film structure is shown to exist, attributed primarily to {approx} 2 nm 'missing island' porosity features close to the substrate; these are most likely associated with coalescence defects as a result of initial ALD growth, as they are not observed in the upper regions of the film. Some 8-9 nm heterogeneities are also present, which may indicate a widespread modulation in the film density pervading the entire film volume, and which likely also give rise to surface roughness. Comparison of the data between different scattering geometries and among a carefully designed sequence of samples has enabled important insights to be derived for the annealing behavior of the ALD HfO{sub 2} films. The main effects of single, brief, high temperature excursions to above 900C are to anneal out some of the fine voids and reduce the mean roughness and interfacial diffuseness of the film. These changes are indicative of densification. However, depending on the film thickness, the annealing behavior at temperatures between 650 and 800C is quite different for single excursion and cyclic anneals. Particularly for thin, just-coalesced films, XRR indicates marked increases in the film thickness and in the mean roughness/diffuseness dimension for cyclic anneals. GISAXS also shows an increase, rather than a reduction, in the void microstructure under these conditions. These changes in the film microstructure appear sufficient to overcome the expected film densification at elevated temperatures with implications for the gate dielectric performance of the films after extended high temperature exposure and cycling, as may occur during gate dielectric fabrication.« less