Statistical simulation of photoresists at EUV and ArF

Biafore, John J.; Smith, Mark D.; Mack, Chris A.; Thackeray, James W.; Gronheid, Roel; Robertson, Stewart A.; Graves, Trey; Blankenship, David

doi:10.1117/12.813551

Cited by 48 publications

(40 citation statements)

References 4 publications

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“…3 Acid or photon shot noise models appear 1932-5150/2011/$25.00 C 2011 SPIE to mathematically describe the general trend between LWR and acid concentration. 4,5 These models typically assume that the initial distribution of photo-acid generator (PAG) in the film is random and uniform. However, our studies at ArF have indicated that PAG segregation can create a nonuniform acid profile through the thickness of a film, especially in thin films with high PAG loadings.…”

Section: Introductionmentioning

confidence: 99%

Resolution–linewidth roughness–sensitivity performance tradeoffs for an extreme ultraviolet polymer bound photo-acid generator resist

Gronheid

2011

J. Micro/Nanolith. MEMS MOEMS

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The goal of this work is to use a combination of experiment and calibrated resist models to understand the impact of photo-acid generator (PAG) and sensitizer loading on the performance of a polymer bound PAG resist based processes for extreme ultraviolet (EUV) lithography. This paper describes construction of a chemically amplified resist model across 248 nm, 193 nm, and EUV imaging wavelengths. Using resist absorbance input as obtained from experiment and modeling, only the acid formation kinetics are allowed to vary across imaging wavelengths. This constraining system affords very good fitting results, which provides high confidence that the extracted parameters from the model have actual physical significance. The quantum efficiency for acid formation in EUV is found to be ∼8× higher than at 248 or 193 nm, due to the excitation mechanism by secondary electrons. Most notably for the polymer bound PAG system under study the model provides an extremely low acid diffusion length (∼8 nm), suggesting an excellent inherent resolution for this material. Next, resist models are created for a series of sensitizer containing polymer bound PAG formulations, where the sensitizer loading is systematically varied. Compared to the reference polymer bound PAG resist without sensitizer the efficiency of acid formation is significantly increased, without a negative impact on either resolution or linewidth roughness. For these materials the quantum efficiency of acid formation in EUV is found to be ∼12× higher than at 248 nm. In these formulations the impact of sensitizer loading on the sizing dose is found to be rather moderate. This may suggest that even at the lowest sensitizer loading studied the energy of the secondary electrons is already efficiently transferred to the PAGs. C 2011 Society of Photo-Optical Instrumentation Engineers (SPIE).

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Section: Introductionmentioning

confidence: 99%

Resolution–linewidth roughness–sensitivity performance tradeoffs for an extreme ultraviolet polymer bound photo-acid generator resist

Gronheid

2011

J. Micro/Nanolith. MEMS MOEMS

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“…The stochastic exposure and resist model used in this work is described in detail by Biafore et al [1,3] elsewhere, so there follows only a brief description.…”

Section: Stochastic Resist Modelmentioning

confidence: 99%

“…Last year, a stochastic exposure and resist model was proposed [1], the model accurately described some basic, experimentally observed, lithographic behaviors, specifically mean CD and 3σ LWR through exposure dose (i.e. exposure latitude) for one photoresist irradiated at two different exposure wavelengths (ArF and EUV).…”

Section: Introductionmentioning

confidence: 99%

Predictive linewidth roughness and CDU simulation using a calibrated physical stochastic resist model

et al. 2010

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A recently developed stochastic resist model, implemented in the PROLITH X3.1 lithography simulation tool, is fitted to experimental data for a commercially available immersion ArF photoresist, EPIC 2013 (Dow Electronic Materials). Calibration is performed using the mean CD and LWR values through focus and dose for three line/space features of varying pitch (dense, semi-dense and isolated). An unweighted Root Mean Squared Error (RMSE) of approximately 1.6 nm is observed when the calibrated model is compared to the experimental data. Although the model is calibrated only to mean CD and LWR values, it is able to accurately predict highly accurate CDU distributions at fixed focus and dose conditions for 1D and 2D(line end shortening) pattern. It is also shown how the stochastic model can be used to describe the bridging behavior often observed at marginal focus and exposure conditions.

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“…There have been several recent studies that have investigated the effects of PAGs that segregate to the top of a resist film 16,17,18 . Again as a means of validating the mesoscale model, a PAG concentration profile in which the PAG segregates to the top of the film was programmed into the simulator.…”

Section: Pag Segregation Impact On Resist Profilementioning

confidence: 99%

Extension of 248 nm Monte Carlo, mesoscale models to 193 nm platforms

et al. 2010

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Current minimum feature sizes in the microelectronics industry dictate that molecular interactions affect process fidelity and produce stochastic excursions like line edge roughness (LER). The composition of future resists is still unknown at this point, and so simulation of various resist platforms should provide useful information about resist design that minimizes LER. In the past, researchers developed a mesoscale model 1, 2 for exploring representative 248 nm resist systems through dynamic Monte Carlo methods and adaptation of critical ionization theory 3 . This molecular modeling uses fundamental interaction energies combined with a Metropolis algorithm to model the full lithographic process (spin coat, PAB, exposure, PEB, and development). Application of this model to 193 nm platforms allows for comparison between 248 and 193 nm resist systems based on molecular interactions. This paper discusses the fundamental modifications involved in adapting the mesoscale model to a 193 nm platform and investigates how this new model predicts well-understood lithographic phenomena including the relationship between LER and aerial image, the relationship between LER and resist components, and the impact of non-uniform PAG distribution in the resist film. Limited comparisons between the 193 nm system and an analogous 248 nm platform will be discussed.

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Statistical simulation of photoresists at EUV and ArF

Cited by 48 publications

References 4 publications

Resolution–linewidth roughness–sensitivity performance tradeoffs for an extreme ultraviolet polymer bound photo-acid generator resist

Resolution–linewidth roughness–sensitivity performance tradeoffs for an extreme ultraviolet polymer bound photo-acid generator resist

Predictive linewidth roughness and CDU simulation using a calibrated physical stochastic resist model

Extension of 248 nm Monte Carlo, mesoscale models to 193 nm platforms

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