Scaled-down deposited underlayers for EUV lithography

Mihir Gupta; Joao Antunes Afonso; Philippe Bezard; Remi Vallat; Roberto Fallica; Hyo Seon Suh; Sandip Halder; Danilo De Simone; Zecheng Liu; Fanyong Ran; Hideaki Fukuda; Yiting Sun; David De Roest; Daniele Piumi

doi:10.1117/12.2660376

30 April 2023 Scaled-down deposited underlayers for EUV lithography

Mihir Gupta, Joao Antunes Afonso, Philippe Bezard, Remi Vallat, Roberto Fallica, Hyo Seon Suh, Sandip Halder, Danilo De Simone, Zecheng Liu, Fanyong Ran, Hideaki Fukuda, Yiting Sun, David De Roest, Daniele Piumi

Author Affiliations +

Proceedings Volume 12498, Advances in Patterning Materials and Processes XL; 124980R (2023) https://doi.org/10.1117/12.2660376
Event: SPIE Advanced Lithography + Patterning, 2023, San Jose, California, United States

Abstract

To further enable device scaling in HVM, new patterning materials are needed to meet the more stringent requirements such as line width and edge roughness (LWR and LER), dose sensitivity, pattern collapse, etch resistance and defectivity. The continuous progression of the shrinking of resist feature sizes will be accompanied by the scaling-down of the resist film thickness to prevent pattern collapse and to compensate for low depth-of-focus for high-NA EUV lithography. However, if we reduce the resist film thickness, we must also reduce the underlayer (UL) hardmask film thickness for optimum pattern transfer. As an alternative to spin-on underlayers, deposited ULs can be a potential candidate as it is possible to produce very thin uniformly deposited ULs, with the freedom to incorporate different elements to improve adhesion and modify etch selectivity. In this paper, we will discuss deposited ULs with film thickness scaled down to 3.5 nm for EUV lithography patterning as well as etch performance for pitch 32 and 28 line/space structures. We will also discuss about the possibility to modify the ULs to match the surface energy of the photoresist in use in order to minimize pattern collapse. Additionally, with scaled-down deposited ULs, we were able to obtain very similar post-litho unbiased roughness values (LWR 2.23 nm and LER 1.7 nm) as 10 nm spin-on reference UL (LWR: 2.26 nm and LER 1.66 nm). We will discuss more such details in terms of surface roughness, dose sensitivity, post-litho and post-etch LWR, LER, pattern collapse and defectivity in the presentation. Such ULs could become useful for high-NA EUV lithography when the litho stack is expected to scale down in thickness.

Conference Presentation

Citation Download Citation

Mihir Gupta, Joao Antunes Afonso, Philippe Bezard, Remi Vallat, Roberto Fallica, Hyo Seon Suh, Sandip Halder, Danilo De Simone, Zecheng Liu, Fanyong Ran, Hideaki Fukuda, Yiting Sun, David De Roest, and Daniele Piumi "Scaled-down deposited underlayers for EUV lithography", Proc. SPIE 12498, Advances in Patterning Materials and Processes XL, 124980R (30 April 2023); https://doi.org/10.1117/12.2660376

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