Relationships between quencher diffusion constant and exposure dose dependences of line width, line edge roughness, and stochastic defect generation in extreme ultraviolet lithography

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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.

Section: Simulation Methodsmentioning

confidence: 99%

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

Kozawa

2023

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“…[19][20][21][22][23][24] This calculation procedure has been reported in detail, elsewhere. 25) The periodic boundary condition was applied in the horizontal direction. The reflective boundary condition was applied in the vertical direction.…”

Section: Simulation and Analysis Methodsmentioning

confidence: 99%

Application of machine learning to stochastic effect analysis of chemically amplified resists used for extreme ultraviolet lithography

Azumagawa

Kozawa

2021

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Chemically amplified resists will be used in the high numerical aperture (NA) tools of extreme ultraviolet lithography. However, stochastic defects are a serious problem for their application to the high NA tools. In this study, the stochastic defect generation was simulated on the basis of the sensitization mechanisms and analyzed to clarify the contribution of process and material parameters using machine learning. The half-pitch HP, the sensitivity s, the total sensitizer concentration C s, the effective reaction radius for deprotection R eff, and the initial standard deviation of the number of protected units per polymer molecule σ i were used as variables. As a result, the exponential function reproduced the simulation results well. s and HP had dominant effects in LER formation. For pinching, s and HP were dominant. σ i had a major effect. For bridging, s and HP were also dominant, the effect of σ i was not major and C s and R eff effects were major.

“…The details of the simulation method including boundary conditions have been reported elsewhere. 29) The effective reaction radii for neutralization and deprotection were set to be 0.5 and 0.1 nm, respectively. Note that the effective reaction radii of chemically amplified EUV resists have been evaluated to be 0.06-0.16 nm.…”

Section: Simulation Model and Methodsmentioning

confidence: 99%

Formulation of trade-off relationships between resolution, line edge roughness, and sensitivity in sub-10 nm half-pitch region for chemically amplified extreme ultraviolet resists

Kozawa¹

2021

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The manufacturing of semiconductor devices using extreme ultraviolet (EUV) lithography started in 2019. A high numerical aperture (NA) tool under development is capable of resolving 8 nm line-and-space optical images and will extend the application of EUV lithography. However, resist materials have not been yet applicable to the production with 8 nm resolution. In this study, the relationships among the half-pitch of line-and-space patterns (resolution), chemical gradient [an indicator of line edge roughness (LER)], and sensitivity were investigated in the sub-10 nm half-pitch region for chemically amplified EUV resists. The chemical gradient was simulated on the basis of their sensitization and reaction mechanisms. The relationship was formulated as a function of total sensitizer concentration (the sum of photoacid generator and photodecomposable quencher concentrations) and the thermalization distance of secondary electrons. The effect of thermalized electrons was well incorporated into the trade-off relationships between resolution, LER, and sensitivity.