Measurement of W-recess profile in advanced node 3D NAND device with IRCD technology utilizing a specialized design-rule compliant target

Nick Keller; Zhuo Chen; Peter Wang; Rostislav Grynko; Troy Ribaudo; G. Andrew Antonelli; Youcheng Wang; Joshua Frederick; Sadao Takabayashi; John Hauck; Dan Engelhard

doi:10.1117/12.2657719

27 April 2023 Measurement of W-recess profile in advanced node 3D NAND device with IRCD technology utilizing a specialized design-rule compliant target

Nick Keller, Zhuo Chen, Peter Wang, Rostislav Grynko, Troy Ribaudo, G. Andrew Antonelli, Youcheng Wang, Joshua Frederick, Sadao Takabayashi, John Hauck, Dan Engelhard

Author Affiliations +

Proceedings Volume 12496, Metrology, Inspection, and Process Control XXXVII; 124961Z (2023) https://doi.org/10.1117/12.2657719
Event: SPIE Advanced Lithography + Patterning, 2023, San Jose, California, United States

Abstract

The W-Recess step for 3D NAND replacement gate process currently has no in-line process control solution. W replacement renders the structure opaque in the ultraviolet/visible/near-infrared (UV/VIS/NIR) region beyond just a few tier layers in the most advanced 3D NAND devices. Additionally, increased word line (WL) slit pitch scaling further reduces the already minimal optical signal from the top of the structure. Through finite-difference time-domain (FDTD) and optical critical dimension (OCD) simulations, we show that a specially designed, design rule-compliant (that is, possessing a slit pitch matching the device) ellipsometry target permits mid-IR light to completely penetrate through oxide metal (OM) pairs, enabling measurement of the W-Recess Z-profile. Furthermore, recent experimental data measured on the designed target in >200 pair 3D NAND node prove that mid-IR light has sensitivity to the slit bottom. An OCD model was developed and showed good design of experiment (DOE) discrimination capability and reference correlation.

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Nick Keller, Zhuo Chen, Peter Wang, Rostislav Grynko, Troy Ribaudo, G. Andrew Antonelli, Youcheng Wang, Joshua Frederick, Sadao Takabayashi, John Hauck, and Dan Engelhard "Measurement of W-recess profile in advanced node 3D NAND device with IRCD technology utilizing a specialized design-rule compliant target", Proc. SPIE 12496, Metrology, Inspection, and Process Control XXXVII, 124961Z (27 April 2023); https://doi.org/10.1117/12.2657719

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