Vectorial pupil optimization to compensate for a polarization effect at full exposure field in lithography

Semiconductor processing is becoming more challenging as integrated circuit dimensions shrink. An increasing number of technologies are being developed for the purpose of ensuring pattern fidelity, and source and mask optimization (SMO) method has outstanding performances. In recent times, owing to the development of the process, more attention has been paid to the process window (PW). As a crucial parameter in lithography, the normalized image log slope (NILS) is strongly correlated with the PW. However, previous methods ignored the NILS in the inverse lithography model of the SMO. They regarded the NILS as the measurement index for forward lithography. This implies that the optimization of the NILS is the result of passive rather than active control, and the final optimization effect is unpredictable. In this study, the NILS is introduced in inverse lithography. The initial NILS is controlled by adding a penalty function to ensure that it continuously increases, thus increasing the exposure latitude and enhancing the PW. For the simulation, two masks typical of a 45-nm-node are selected. The results indicate that this method can effectively enhance the PW. With guaranteed pattern fidelity, the NILS of the two mask layouts increase by 16% and 9%, and the exposure latitudes increase by 21.5% and 21.7%.

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Initiative global NILS control in source and mask optimization for process window enhancement

duo

Peng

Song

et al. 2023

Appl. Opt.

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High efficiency regulation method to generate an illumination source by adopting the micromirror array in DUV lithography

Chen,

Li,

Liu

2024

Appl. Opt.

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Source and mask optimization (SMO) is an important lithography resolution enhancement technique for 22 nm technology nodes and beyond in lithography. This technique generates freeform sources by adjusting the inclination angle of the micromirror array (MMA). In this paper, a high efficiency regulation method to generate an illumination source by adopting the micromirror array in DUV lithography is proposed. The number and inclination angles of micromirrors required for adjustment to convert the initial source into any illumination source are quickly and accurately obtained by using the proposed method. The illumination source is obtained on the pupil plane by adjusting the inclination angles of some micromirrors. The simulation results show that the initial source is converted into another illumination source with different complexities by adjusting some micromirrors. Compared with the traditional MMA allocation method, when the initial source is the freeform source, the regulation efficiency of micromirrors has been improved by at least 20%. The method reduces the regulation time of micromirrors and the number of micromirrors required for adjustment. Moreover, the number of micromirrors required for adjustment is positively correlated with the coherence coefficient. The results illustrate that this method is effective and has significant engineering implications.

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Tatian polynomial-based annular pupil wavefront optimization method for high-NA extreme ultraviolet lithography

Yuan,

Li,

et al. 2024

Appl. Opt.

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The advanced technology node has an exact error tolerance. The effect of projection objective aberration on imaging cannot be neglected. In order to reduce the effect of aberration, considering the central obscuration of the high-NA extreme ultraviolet projection objective, we propose a Tatian polynomial-based annular pupil wavefront optimization (TBAPWO) method. An active pupil consisting of 64-term Tatian polynomials is incorporated into the imaging model. The suitable coefficients of the Tatian polynomials are solved using the gradient iteration method. The optimized active pupil can improve lithographic imaging quality. Simulation results show that the TBAPWO method can effectively reduce the pattern error of imaging by more than 30%, which indicates that the effect of aberration on imaging is controlled.

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Vectorial pupil optimization to compensate for a polarization effect at full exposure field in lithography

Cited by 3 publications

References 29 publications

Initiative global NILS control in source and mask optimization for process window enhancement

Initiative global NILS control in source and mask optimization for process window enhancement

High efficiency regulation method to generate an illumination source by adopting the micromirror array in DUV lithography

Tatian polynomial-based annular pupil wavefront optimization method for high-NA extreme ultraviolet lithography

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