Optimum mask and source patterns to print a given shape

Rosenbluth, Alan E.; Bukofsky, S.; Hibbs, M.; Lai, Kafai; Molless, Antoinette F.; Singh, Rama N.; Wong, Alfred K. K.

doi:10.1117/12.435748

Cited by 117 publications

(83 citation statements)

References 7 publications

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“…Therefore, it is a requirement that the optical integrator does preserve the shape of the input pupil. This is of particular importance in the case of more complex illumination pupils, as, e.g., used in source mask optimized lithographic processes, where very complex masks and also very complex illumination pupils are used [19] .…”

Section: Lithography Systemsmentioning

confidence: 99%

“…Since the beginning of microlithography optical arrays are used for lithography illumination systems and mask aligners. Only recently the use of high performance optical arrays allowed the improvement of mask aligners [17] , as well the design of lithographic illumination systems with very complex and variable pupil shapes, as, for example, used in modern source-mask optimized lithographic processes [18,19] . Moreover, variations of optical arrays in terms of gratings and holographic elements have been suggested [20,21] .…”

Section: Introductionmentioning

confidence: 99%

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Phase space approach to the use of integrator rods and optical arrays in illumination systems

Rausch

Herkommer

2012

Advanced Optical Technologies

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Integrator rods and optical arrays are the most frequently used components in illumination design for homogenizing radiation fi elds. However, these two standard components are very different in their performance and characteristics. This tutorial is aimed to illustrate the operation principle, basic design rules and the performance of those components. It should guide the optical designer towards the optimum choice for the individual illumination application. To illustrate the functionality of integrator rods and optical arrays simultaneously in angle and position, the concept of phase space is introduced. Here the effect of the homogenizing components can nicely be illustrated in the form of phase space transformations. This offers new insight and a different perspective onto the employment and characteristics of those elements.

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Section: Lithography Systemsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Phase space approach to the use of integrator rods and optical arrays in illumination systems

Rausch

Herkommer

2012

Advanced Optical Technologies

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“…Rosenbluth et al used a Fourier Transform method to calculate the mask pattern that provides the optimized wave front, thus performing joint source and mask optimization. This method was able to greatly enhance the process window [2]. However, source optimization is limited to controlling the magnitude and placement of diffraction energy in the lens pupil, and phase control is limited to that made available through phase shifting at the mask plane.…”

Section: Introductionmentioning

confidence: 99%

Extending SMO into the lens pupil domain

et al. 2011

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As semiconductor lithography is pushed to smaller dimensions, the process yields tend to suffer due to subwavelength imaging effects. In response, resolution enhancement technologies have been employed together with optimization techniques, specifically source mask optimization (SMO), which finely tunes the process by simultaneously optimizing the source shape and mask features. However, SMO has a limitation in that it fails to compensate for undesired phase effects. For mask features on the order of the wavelength, the topography of the mask can induce aberrations which bring asymmetry to the focus-exposure matrix (FEM) and ultimately decrease the process window. This paper examines the dependency of FEM asymmetry on factors such as the illumination coherency and lens induced spherical aberration. It is shown that lens induced primary spherical aberration strongly impacts the symmetry of the FEM. In this work, phase correction is achieved by incorporating the pupil plane in an optimization. It is shown that primary spherical aberration can correct for effects including the degraded depth of focus and the tilt in the FEM for a dual trench mask. A pupil function with an optimized coefficient of primary spherical aberration balances the spherical aberration induced by the mask topography.

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“…3,4 In 2002, Rosenbluth et al proposed the first source mask optimization (SMO) method that exploits the synergy between the source and mask to achieve a higher resolution. 5 Since then, a number of SMO methods have been proposed in the literature. [6][7][8][9] Most methods are based on a scalar imaging model that is no longer accurate for a numerical aperture ðNAÞ > 0.…”

Section: Introductionmentioning

confidence: 99%

Parametric source-mask-numerical aperture co-optimization for immersion lithography

Guo

Dong

et al. 2014

J. Micro/Nanolith. MEMS MOEMS

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Abstract. Source mask optimization (SMO) is a leading resolution enhancement technique in immersion lithography at the 45-nm node and beyond. Current SMO approaches, however, fix the numerical aperture (NA), which has a strong impact on the depth of focus (DOF). A higher NA could realize a higher resolution but reduce the DOF; it is very important to balance the requirements of NA between resolution and the DOF. In addition, current SMO methods usually result in complicated source and mask patterns that are expensive or difficult to fabricate. This paper proposes a parametric source-mask-NA co-optimization (SMNO) method to improve the pattern fidelity, extend the DOF, and reduce the complexity of the source and mask. An analytic cost function is first composed based on an integrative vector imaging model, in which a differentiable function is applied to formulate the source and mask patterns. Then, the derivative of the cost function is deduced and a gradient-based algorithm is used to solve the SMNO problem. Simulation results show that the proposed SMNO can achieve the optimum combination of parametric source, mask, and NA to maintain high pattern fidelity within a large DOF. In addition, the complexities of the source and mask are effectively reduced after optimization. © The Authors. Published by SPIE under a Creative Commons Attribution 3.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI.

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Optimum mask and source patterns to print a given shape

Cited by 117 publications

References 7 publications

Phase space approach to the use of integrator rods and optical arrays in illumination systems

Phase space approach to the use of integrator rods and optical arrays in illumination systems

Extending SMO into the lens pupil domain

Parametric source-mask-numerical aperture co-optimization for immersion lithography

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