Stochastic defect generation depending on tetraalkylhydroxide aqueous developers in extreme ultraviolet lithography

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The high-volume production of semiconductor devices with extreme ultraviolet (EUV) lithography started in 2019. During the development of EUV lithography, the resist materials had always been ranked high in the focus area for its realization. The trade-off relationships between resolution, line width roughness, and sensitivity were the most serious problem. The EUV lithography started with the use of chemically amplified resists after the material chemistry was optimized on the basis of radiation chemistry. The increase of numerical aperture has been scheduled to enhance the optical resolution. For the realization of next-generation lithography, the suppression of stochastic effects is the most important issue. A highly absorptive material is a key to the suppression of stochastic effects. The development of next-generation EUV resists has progressed around chemically amplified resists, metal oxide resists, and main-chain-scission type resists. EUV resists are reviewed from the viewpoint of material design for the suppression of stochastic effects.

Section: Developmentmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Design strategy of extreme ultraviolet resists

Kozawa

2024

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“…In the development of resist materials and processes, the suppression of stochastically generated defects 5) is the most important issue. [6][7][8][9][10] The development process (i.e., the dissolution of resist films by a developer) is a key process in the suppression of stochastic effects. 11) To suppress stochastic effects, an increase in the number of absorbed photons is essential.…”

Section: Introductionmentioning

confidence: 99%

Effects of substituents in triphenylsulfonium cation on its radiation-induced decomposition and dissolution kinetics of chemically amplified resists

Tsuda,

Muroya,

Okamoto

et al. 2024

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The suppression of stochastic effects is the most important issue in the development of resist materials. To suppress the stochastic effects in chemically amplified resists, a high acid generator concentration is required, which, however, likely affects the dissolution kinetics of resist films. In this study, the effects of substituents in the phenyl group of triphenylsulfonium triflate (TPS-TF) on the decomposition and dissolution kinetics of poly(4-hydroxystyrene) (PHS) films dispersed with monosubstituted TPS-TF were investigated using electron pulse radiolysis, γ-radiolysis, electron radiolysis, and quartz crystal microbalance. The phenyl group of TPS-TF was substituted with fluorine, iodine, or methyl groups at the fourth position. The electronegativity of the substituents had little effect on the reaction rate of the methanol-solvated electrons. The dipole moment of the TPS cation affected the C-S bond cleavage. The monosubstitution of the phenyl group of the TPS cation significantly affected the dissolution rate of the PHS films.

“…Although the trade-off relationships are still a problem, the suppression of stochastic defects is currently the most serious issue in the development of EUV resists. [5][6][7][8][9][10] The stochastic defects are generated because the formation of resist patterns is a consequence of stochastic processes.…”

Section: Introductionmentioning

confidence: 99%

Defect risks at interfaces of chemically amplified resists in extreme ultraviolet lithography process

Kozawa

2023

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In extreme ultraviolet (EUV) lithography, stochastically generated defects (stochastic defects) are a significant issue. In this study, the formation of the latent images of line-and-space resist patterns was simulated to assess the dependence of defect risks on the conditions of resist interfaces. The protected unit distribution was calculated on the basis of the sensitization and reaction mechanisms of chemically amplified EUV resists using a Monte Carlo method. The pinching and bridging risks were calculated to be 7.4×10-3-2.0×10-2 and 1.5×10-3-2.6×10-1, respectively, depending on the boundary conditions of low-energy secondary electrons at the interfaces. Using the obtained defect risks, we roughly estimated that the impacts of interfacial effects on pinching and bridging probabilities for low-energy secondary electrons were more than one order of magnitude and more than six orders of magnitude, respectively. Controlling the low-energy electrons at the interfaces is important for the suppression of stochastic defects.