Measurements of an Effective Longitudinal Coherence Length in Transmission Small Angle X-ray Scatterings

Liu, Chun‐Ting; He, Bo-Ching; Chen, Guo-Dung; Chang, Alice C.; Wu, Wen‐Li; Fu, Wei‐En

doi:10.3390/nano10081549

Cited by 4 publications

(6 citation statements)

References 12 publications

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“…It is noteworthy that the effective coherence length is not just a measure of the specular purity of the incident x-ray and it also depends strongly on the scattering angle. 34…”

Section: X-ray Reflectivity As a Cdsaxs Toolmentioning

confidence: 99%

“…It is noteworthy that the effective coherence length is not just a measure of the specular purity of the incident x-ray and it also depends strongly on the scattering angle. 34 CDSAXS was a part of a joint effort between NIST and IBM on lithography materials, QH Lin was the initiating member from IBM side. This joint work was partially funded by a Lithography Project of DARPA for two years.…”

Section: X-ray Reflectivity As a Cdsaxs Toolmentioning

confidence: 99%

“…For 3D NAND and DRAM structures, a further increase in the number of layers beyond the current value will result in higher scattering intensity until the sample height reaches the effective longitudinal coherence length of the incident beam. It is noteworthy that the effective coherence length is not just a measure of the specular purity of the incident x-ray and it also depends strongly on the scattering angle 34 …”

Section: Prospects For Cdsaxsmentioning

confidence: 99%

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Review of the key milestones in the development of critical dimension small angle x-ray scattering at National Institute of Standards and Technology

Kline

Jones

et al. 2023

J. Micro/Nanopattern. Mats. Metro.

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An x-ray scattering based metrology was conceived over 20 years ago as part of a collaboration between National Institute of Standards and Technology (NIST) and International Business Machines Corporation (IBM) to evaluate the performance of lithographic patterning materials for the semiconductor industry. This methodology treated a periodic array of lithographic structures as a diffraction grating and focused on extracting the physical dimensions of the structures in the grating by analyzing the diffraction patterns. In the early stages of the work the focus was on developing the transmission small-angle x-ray scattering (tSAXS) as a metrology tool to measure the critical dimensions (CD) of the lithographic features vital to the integrated circuit chip fabrication. Later, the focus shifted to include grazing incident small-angle x-ray scattering and x-ray reflectivity as parts of the CD metrology tool due to their unique capabilities. Frequently the term critical dimension small-angle x-ray scattering (CDSAXS) has been used as a synonym for the metrology of using tSAXS for CD measurements without mentioning transmission. Various milestones in the CDSAXS development are reviewed in this article together with some prospects regarding the future growth of x-ray-based metrology for complex three-dimensional nanostructures important to semiconductor industries.

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“…It is noteworthy that the effective coherence length is not just a measure of the specular purity of the incident x-ray and it also depends strongly on the scattering angle. 34…”

Section: X-ray Reflectivity As a Cdsaxs Toolmentioning

confidence: 99%

Section: X-ray Reflectivity As a Cdsaxs Toolmentioning

confidence: 99%

Section: Prospects For Cdsaxsmentioning

confidence: 99%

See 1 more Smart Citation

Review of the key milestones in the development of critical dimension small angle x-ray scattering at National Institute of Standards and Technology

Kline

Jones

et al. 2023

J. Micro/Nanopattern. Mats. Metro.

Self Cite

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“…It is the purpose of this manuscript to quantitatively discuss the relation between the observed enhancement in scattering intensity and the number of layers or the sample thickness. The discussion will return to our previous work on the scattering intensities enhancement by placing an enhancement object close to the target object [10] as well as the effective longitudinal coherence length in tSAXS measurements [11,12]. Now it is a known fact that the observed tSAXS intensity, especially in the low angle region, gets enhanced significantly as the sample thickness or the number of layers goes up.…”

Section: Introductionmentioning

confidence: 98%

The intensity enhancement of transmission small angle x-ray scattering from nanostructures with a high aspect ratio

2023

Surf. Topogr.: Metrol. Prop.

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Transmission small angle X-ray scattering (tSAXS) has been developed as a metrology for the critical dimension (CD) measurements to facilitate integrated circuit (IC) chip fabrications. Synchrotron X-ray sources were used for their high brilliance and a wavelength less than one tenth of a nanometer was chosen for its high penetration power to enable transmission measurements through a silicon wafer with a nominal thickness of 0.7 mm. A major hold back preventing tSAXS from reaching wide applications in IC fabrication is the lack of high brilliance laboratory-based X-ray sources. Within the last few years, even without any major breakthrough in X-ray source technology, this tSAXS metrology has finally been used for 3D NAND and DRAM, i.e., memory chips with tall or high aspect ratio (HAR) architectures. The scattering intensities from HAR structures will be discussed quantitatively in terms of the sample height and the effective longitudinal coherence length of the incident X-ray.

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“…AFM has a high resolution and full 3D contouring capability 3 , but its ability to measure shallow structures' internal contours and maximum measurable aspect ratio is limited by the tip shape and insufficient stiffness, and its measurement throughput may not meet in-line measurement requirements. X-ray techniques such as small-angle X-ray scattering (SAXS) 4 or X-ray fluorescence (XRF) 5 can measure tiny devices, but require a high-power X-ray source and a specialized work environment, limiting their practicality. WLI offers nondestructive, full-field measurement with decent resolution, but accurately measuring the inner parameters of high-aspectratio structures remains a challenge 6 .…”

Section: Introductionmentioning

confidence: 99%

Artificial-neural-network-assisted DUV scatterometry for OCD on HAR sub-micron structures

Chein

Yang

et al. 2023

Metrology, Inspection, and Process Control XXXVII

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A neural network-assisted spectral scatterometry method is presented to measure multi-dimensional critical dimensions (CDs) on high aspect ratio (HAR) structures with micron or submicron scales. With the rise of 3D integrated circuit packaging, there is a need for accurate characterization of HAR sub-micron structures. This method uses DUV scatterometry and a broadband light source from DUV to visible light to gather multi-channel reflection data. The inverse modeling method and artificial neural network model enable accurate measurement of multiple CDs of test structures. The results showed accurate measurement of deep trench critical dimensions with a nominal line width of 0.6 μm and aspect ratio up to 5:1, with accuracy within a few nanometers comparable to SEM results using the same sample.

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Measurements of an Effective Longitudinal Coherence Length in Transmission Small Angle X-ray Scatterings

Cited by 4 publications

References 12 publications

Review of the key milestones in the development of critical dimension small angle x-ray scattering at National Institute of Standards and Technology

Review of the key milestones in the development of critical dimension small angle x-ray scattering at National Institute of Standards and Technology

The intensity enhancement of transmission small angle x-ray scattering from nanostructures with a high aspect ratio

Artificial-neural-network-assisted DUV scatterometry for OCD on HAR sub-micron structures

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