Dependence of dose rate on the sensitivity of the resist under ultra-high flux extreme ultraviolet (EUV) pulse irradiation

Okamoto, Kazumasa; Kawai, Shunpei; Ikari, Yuta; Hori, Shinya; Konda, Akihiro; Ueno, Koki; Arai, Yohei; Ishino, Masahiko; Dinh, Thanh-Hung; Nishikino, Masaharu; Kon, Akira; Owada, Shigeki; Inubushi, Yuichi; Kinoshita, Hiroo; Kozawa, Takahiro

doi:10.35848/1882-0786/abfca3

Cited by 4 publications

(4 citation statements)

References 31 publications

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“…[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. The wafer stage operates the temperature control to minimize in-plane distortion problems.…”

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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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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“…There were a lot of efforts to improve the critical features’ sizes of the chemically amplified resist (CAR) profile. Optimizing the process conditions is always a traditional and convenient way 1 – 5 as most of the process conditions are available in the recipes on the tracker. For example, optimizing the exposure energy can help improve the line width roughness, 4 and optimizing the focal position or exposure energy can reduce the line width error 5 .…”

Section: Introductionmentioning

confidence: 99%

Optimization of chemically amplified resist formulation based on simple random sampling and kernel density estimation

Kong

Dong

et al. 2023

J. Micro/Nanopattern. Mats. Metro.

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Formulation optimization plays an important role in the research and development of chemically amplified resist (CAR). However, the CAR profile after development process is influenced by multiple resist parameters and process conditions, so it is hard to determine the optimal CAR formulation in the multivariate problem. An optimization method for the CAR formulation is developed. The simple random sampling is applied to each CAR parameter's value range independently, and the combinations of these samples from different parameters are used in the simulation of lithography profiles. Kernel density estimation is applied to analyze the simulation results. Then the CAR formulation is optimized based on the probability density distribution from the analysis results. The verification results show that the proposed optimization method can greatly improve the stability of the CAR formulation and thus generating acceptable critical features' sizes of the CAR profile.

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“…Prior to etching and patterning, defects such as line edge roughness (LER) could be attributed to (1) the multistep fabrication processes for high-volume manufacturing which include spin-coating, varied sensitivities to EUV source, mask implementation, and multiple thermal treatments, and (2) the multicomponent formulation used in these chemically amplified resists (CARs) for modified solubility to attain patterns with critical dimensions. 1,2 Optimizing these intermediate variables by tuning external parameters of these treatments may be one possible solution, however, understanding and refining the molecular structure that sets the foundation of irradiation sensitivity is key to produce a latent image with high resolution. [3][4][5] In particular, the additive loadings in positive-tone CARs, such as the photoacid generator (PAG) and quencher, are key components for controlled acid-catalyzed film deprotection and inadvertently produce statistical variations.…”

Section: Introductionmentioning

confidence: 99%

“…Film stochastics in extreme ultraviolet (EUV) lithography remain an elusive challenge to mitigate due to the range of defect sources and the lack of metrologies to accurately describe these processes. Prior to etching and patterning, defects such as line edge roughness (LER) could be attributed to (1) the multistep fabrication processes for high-volume manufacturing which include spin-coating, varied sensitivities to EUV source, mask implementation, and multiple thermal treatments, and (2) the multicomponent formulation used in these chemically amplified resists (CARs) for modified solubility to attain patterns with critical dimensions 1 , 2 . Optimizing these intermediate variables by tuning external parameters of these treatments may be one possible solution, however, understanding and refining the molecular structure that sets the foundation of irradiation sensitivity is key to produce a latent image with high resolution 3 …”

Section: Introductionmentioning

confidence: 99%

Evaluating nanoscale molecular homogeneity in extreme ultraviolet resists with nanoprojectile secondary ion mass spectrometry

Cruz

Verkhoturov

et al. 2022

J. Micro/Nanopattern. Mats. Metro.

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.Characterizing chemical changes in photoresists during fabrication processes is critical to understanding how nanometric defects contribute to film stochastics. We used nanoprojectile secondary ion mass spectrometry (NP-SIMS) to evaluate the nanoscale homogeneity of components in positive-tone extreme ultraviolet resists. NP-SIMS was operated in the event-by-event bombardment/detection mode, where a suite of individual gold nanoprojectiles separated in time and space stochastically bombard the surface. Each impact ejects secondary ions from a volume 10 to 15 nm in diameter and up to 10 nm in depth allowing for analysis of colocalized moieties with high spatial resolution. Individual partially exposed extreme ultraviolet resists were analyzed after light exposure, postexposure bake, and development. Results showed an expected increase in protonated quencher versus exposure dose, while after development, we observed increased abundance in the remaining film. The latter, we attribute to poor solubility in the developing solvent. Examining the photoacid generator (PAG), we found decreased PAG cation abundance versus exposure dose in the exposed films, likely due to photodecomposition of the PAG cation. Moreover, after the development, we observed decreased homogeneity of PAG ions, which we attribute to preferential extraction caused by ion-exchange interactions with the developer. We found that the insoluble moieties persisting on the surface after the development were relatively rich in the protecting group, likely due to uneven deprotection of the polymer. Overall, NP-SIMS allows to characterize the resist at the nanoscale and identify conditions that lead to defect formation.

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Dependence of dose rate on the sensitivity of the resist under ultra-high flux extreme ultraviolet (EUV) pulse irradiation

Cited by 4 publications

References 31 publications

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

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

Optimization of chemically amplified resist formulation based on simple random sampling and kernel density estimation

Evaluating nanoscale molecular homogeneity in extreme ultraviolet resists with nanoprojectile secondary ion mass spectrometry

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