An evaluation of a new side-wall-angle measurement technique for mask patterns by CD-SEM

Hakii, Hidemitsu; Yonekura, Isao; Kawashita, Masashi; Kojima, Yosuke; Sakamoto, Yoshifumi; Tanaka, Keishi

doi:10.1117/12.824280

Cited by 1 publication

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“…If there is a large deviation in the final etched pattern, it will deteriorate the subsequent fabrication of further layers on the nanostructure, and it may even lead to the failure of the chip. The verticality of the SWA, therefore, has become a crucial factor in mask fabrication [2]. Non-destructive determination of the SWA, especially for reconstruction of steep SWA with high precision is obviously indispensable in nanostructure metrology.…”

Section: Introductionmentioning

confidence: 99%

Determination of steep sidewall angle using polarization-sensitive asymmetric scattering

Dou

Pereira

Min

et al. 2021

Meas. Sci. Technol.

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The sidewall angle (SWA) of a nanostructure exerts influence on the performance of the nanostructure and plays an important role in processing nano-structural chips. It is still a great challenge to determine steep SWAs from far field measurements especially when the SWAs are close to 90 • . Here, we propose a far-field detection system to determine steep SWA of a cliff-shape step structure on a silicon substrate by combining a split detector with a scanning method. The far-field radiation field is asymmetric due to the scattering of the step structure, and further numerical analysis demonstrates the reliability of this far-field measurement method. In the simulations, two key variables, i.e. the polarization state and the focus position of the incident laser beam, are considered to explore their impacts. By scanning over the structure laterally and longitudinally with both TE and TM polarizations, polarization effects on the far-field occur. These effects show higher sensitivity to steep SWA variation for TM polarization as compared to TE. Furthermore, with a comprehensive longitudinal scanning analysis for the TM polarization case, a feasible focus interval can be optimized to retrieve the steep SWA. As the proposed method is fast, highly sensitive and easy to implement, it provides a powerful approach to investigate the scattering behavior of nanostructures.

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Section: Introductionmentioning

confidence: 99%