Optimal phase shift and reflectance for high numerical aperture EUV phase shift mask

Kang, In-Hwa; Park, Jang-Gun; Kim, Minwoo; Lee, Junhyeong; Oh, Hye−Keun

doi:10.1117/12.2602035

Cited by 1 publication

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“…As the semiconductor circuit has been miniaturized, the error tolerance has decreased. [1][2][3] However, the dose performance needed to form the pattern still requires more than the sensitivity that the photo-acid generator and quencher can react to. 4,5) If thermal strain at the nanometer level occurs in the EUV process targeting a critical dimension (CD) of 10 nm or below, it will seriously affect patterning.…”

Section: Introductionmentioning

confidence: 99%

Overlay and CD uniformity variation due to wafer thermal deformation caused by EUV exposure

Ko¹,

Choi²,

Kim³

et al. 2023

Jpn. J. Appl. Phys.

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Extreme ultraviolet lithography (EUVL) process allows for the manufacturing of better- performance chips. However, the EUV exposure process might contribute to significant variations in the patterns of circuits, which cause serious image placement and flatness change. And, during the exposure, the EUV absorption might cause local wafer thermal deformation that might cause the overlay and local critical dimension (CD) variation. In this study, we investigated the wafer thermal deformation with different CDs and pitches with EUV exposure and the thermo-mechanical behavior of the photoresist using the finite element method (FEM) simulation. It is found that the thermal deformation caused during EUV exposure is different inside a die. In the direction along the scan, thermal deformation is increased as it is nearer to the center of the slit. The deformation in the perpendicular direction is increased as it approaches the edges and deforms in the opposite direction relative to the center of the slit. In both directions, the thermal deformation increases gradually as the scan progresses, and it could be as large as ~ 1.5 nm in a die. There was no difference in thermal deformation by CD change, but it is changed with pitch.

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