Small angle x-ray scattering metrology for sidewall angle and cross section of nanometer scale line gratings

Hu, Tianyi; Jones, Ronald L.; Wu, Wen Li; Lin, Eric K.; Lin, Qinghuang; Keane, Denis T.; Weigand, Steve; Quintana, J. P.

doi:10.1063/1.1773376

Cited by 74 publications

(51 citation statements)

References 11 publications

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“…Some discrepancy is also to be expected since the sample is somewhat different. CD-SAXS [11,12] results come from a relatively large (around 100 µm by 100 µm) area of the sample, and provide excellent quality information on the placement, widths, sizes, 3D shape, etc. and in many cases on overall roughness of dense lines.…”

Section: Resultsmentioning

confidence: 99%

10nm three-dimensional CD-SEM metrology

Vladár

Villarrubia²,

Chawla

et al. 2014

SPIE Proceedings

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The shape and dimensions of a challenging pattern have been measured using a model-based library scanning electron microscope (MBL SEM) technique. The sample consisted of a 4-line repeating pattern. Lines were narrow (10 nm), asymmetric (different edge angles and significant rounding on one corner but not the other), and situated in a complex neighborhood, with neighboring lines as little as 10 nm or as much as 28 nm distant. The shape cross-section determined by this method was compared to transmission electron microscopy (TEM) and critical dimension small angle x-ray scattering (CD-SAXS) measurements of the same sample with good agreement. A recently-developed image composition method was used to obtain sharp SEM images, in which blur from vibration and drift were minimized. A Monte Carlo SEM simulator (JMONSEL) produced a model-based library that was interpolated to produce the best match to measured SEM images. Three geometrical and instrument parameterizations were tried. The first was a trapezoidal geometry. In the second one corner was significantly rounded. In the last, the electron beam was permitted to arrive with stray tilt. At each stage, the fit to the data improved by a statistically significant amount, demonstrating that the measurement remained sensitive to the new parameter. Because the measured values represent the average unit cell, the associated repeatabilities are at the tenths of a nanometer level, similar to scatterometry and other area-averaging techniques, but the SEM's native high spatial resolution also permitted observation of defects and other local departures from the average.

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Section: Resultsmentioning

confidence: 99%

10nm three-dimensional CD-SEM metrology

Vladár

Villarrubia²,

Chawla

et al. 2014

SPIE Proceedings

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“…A good approach for better understanding is then to make artificial periodic roughness that can produce well defined diffracted orders due to the roughness in addition to the normal diffracted orders due to the grating itself. This type of approach has already been proposed to take into account innovative critical dimension small angle x-ray scattering measurements (16)(17) and additional diffraction peaks due to the correlated roughness have been evidenced in some cases using this technique. In the present study, we have fabricated different grating samples with controlled periodic LER and LWR.…”

Section: Introductionmentioning

confidence: 98%

Optical Fourier transform scatterometry for LER and LWR metrology

et al. 2005

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We present an innovating instrument based on optical Fourier transform (OFT) capable to measure simultaneously the specular and non specular diffraction pattern of sub-micronic periodic structures. The sample is illuminated at fixed wavelength (green laser) versus a large angular aperture both in incidence (0 to 80°) and azimuth (0 to 180°). In the present paper we focus on the possibility to measure line edge roughness (LER) and line width roughness (LWR) using this new technique. To understand the problem, different gratings with artificial periodic LER and LWR roughness have been fabricated and characterized precisely by atomic force microscopy (AFM). Different light scattering measurements have been performed using the OFT instrument with different illuminations in order to understand precisely the optical behavior of these systems. We show that we can distinguish LER and LWR by measuring simultaneously the diffracted contributions coming from the grating and from the periodic roughness. In phase LER with small LWR does not give first order diffraction contribution for the periodic roughness. In contrast, LER in opposite phase with large LWR gives a strong contribution for the first order of diffraction of the periodic roughness. In any case, the sensitivity to LER and LWR is better than 5nm for 500nm period gratings measured at 532nm. This result can be extended to samples with real LER and LWR. It shows without ambiguity that simultaneous measurement of the specular and diffracted light diffraction patterns is necessary to extract separately the two parameters.

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“…As a consequence, over the years several methods have been designed to measure, as precisely as possible, the SWA value. [3][4][5] Available techniques try to exploit all the fundamental properties of light, e.g. the energy spectra and the energy density of light signals, but in the past few years much attention has been given to the study of the interaction between angular momentum and matter.…”

Section: Introductionmentioning

confidence: 99%

Spatial mode projection for side-wall angle measurements

et al. 2015

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Finding a fast and precise method to measure the side-wall angle of periodic (or non-periodic) structures is still a very challenging problem in lithographic applications. For this reason, over the years, many techniques have been proposed to circumvent this limitation, with the final goal to give the most precise geometrical description of particular targets. Recently, the investigation of the optical angular momentum, which is encoded in the light's spiral spectrum, has brought new ways to acquire information about objects. In this work, we built an optical setup to put forward a new method to detect the side-wall angle in a fast and reliable way. The novelty of this work is the use of the spiral spectrum of a light beam for angle measurements, i.e. the light transmitted by a particular structure is projected onto properly tailored spatial modes and only the most sensitive mode to the side wall angle is detected and processed.

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Small angle x-ray scattering metrology for sidewall angle and cross section of nanometer scale line gratings

Cited by 74 publications

References 11 publications

10nm three-dimensional CD-SEM metrology

10nm three-dimensional CD-SEM metrology

Optical Fourier transform scatterometry for LER and LWR metrology

Spatial mode projection for side-wall angle measurements

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