Accuracy assessment of 3D SEM metrology of microlenses

Zeinab Abdallah; Aurélien Fay; Stéphane Bonnet

doi:10.1117/12.3028806

18 September 2024 Accuracy assessment of 3D SEM metrology of microlenses

Zeinab Abdallah, Aurélien Fay, Stéphane Bonnet

Proceedings Volume 13273, 39th European Mask and Lithography Conference (EMLC 2024); 132730C (2024) https://doi.org/10.1117/12.3028806
Event: 39th European Mask and Lithography Conference (EMLC 2024), 2024, Grenoble, France

Abstract

In the rapidly advancing field of microelectronics, accurate and non-destructive 3D metrology is crucial for both advanced nodes and More-than-Moore devices. We propose a novel strategy utilizing Scanning Electron Microscopy (SEM) to achieve fast and non-destructive topographical measurements of microscopic objects. Microlens-like 3D structures were patterned on 300nm wafers using grayscale i-line lithography. These structures were imaged using a SEM tool equipped with a four-quadrant secondary electron (SE) detector, and the resulting data were co-registered with high-resolution Atomic Force Microscopy (AFM) measurements for 3D reference. We analyzed the analytical forward-based SEM model and distinguished between two models, focusing first on Slowko’s model. The updated SEM model denotes as Vynnyk model better describes the SEM signal across the entire microlens surface, including regions oriented towards and opposite the active detector. We developed a method to compute the radius of the microlens directly from the SEM image and refined the height estimation process using this radius calculation. Our 3D reconstruction strategy yielded accurate results for various microlenses with radii ranging from 800nm to 1400nm, achieving a height error below 2%. In conclusion, 3D SEM metrology demonstrates good overall accuracy for microlenses and paves the way towards in-line statistical process control studies, offering a reliable method to compute critical dimensions and improve the precision of height estimation.

Citation Download Citation

Zeinab Abdallah, Aurélien Fay, and Stéphane Bonnet "Accuracy assessment of 3D SEM metrology of microlenses", Proc. SPIE 13273, 39th European Mask and Lithography Conference (EMLC 2024), 132730C (18 September 2024); https://doi.org/10.1117/12.3028806

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KEYWORDS

Scanning electron microscopy

Microlens

3D modeling

Sensors

3D image reconstruction

3D metrology

3D image processing

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