Grouping design method with real ray tracing model for extreme ultraviolet lithographic objective

Cao, Zhen; Li, Yanqiu; Liu, Fei

doi:10.1117/1.oe.52.12.125102

Cited by 12 publications

(5 citation statements)

References 10 publications

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“…An illumination system for a given projection objective 20 was designed with the configuration described above. Parameters of the objective are listed in Table 1.…”

Section: Design Of the Illumination Systemmentioning

confidence: 99%

Illumination system with freeform fly’s eye to generate pixelated pupil prescribed by source-mask optimization in extreme ultraviolet lithography

Jiang

Mei

et al. 2017

Opt. Eng

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Abstract. Source-mask optimization (SMO) has emerged as a key technique for 7-nm node and beyond in extreme ultraviolet (EUV) lithography. The pupil required by SMO is usually pixelated, with a free choice of intensity per pixel. However, due to the discrete nature of the EUV illumination system, pupil intensity in current EUV SMO must also be discretized. An illumination system with a freeform fly's eye that is able to generate the pixelated pupil is proposed. Clear apertures of the field facets in the fly's eye are different from each other so that the intensity of each pixel on the pupil can meet the requirements of SMO. Each of the field facets is constructed with a freeform surface to get the required arc-shaped illuminated area on the reticle. A method integrated with a numerical method and an optimization process is used to design the freeform surface of the field facets. The simulation result of the design for a prescribed freeform pixelated pupil shows that the uniformity on the reticle is 96.4%, and the pupil intensity error is approximated to be 0.035. The results indicate that the system is effective in generating the required freeform pixelated pupil and reducing the restrictions imposed on the SMO process in EUV lithography.

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“…An illumination system for a given projection objective 20 was designed with the configuration described above. Parameters of the objective are listed in Table 1.…”

Section: Design Of the Illumination Systemmentioning

confidence: 99%

Illumination system with freeform fly’s eye to generate pixelated pupil prescribed by source-mask optimization in extreme ultraviolet lithography

Jiang

Mei

et al. 2017

Opt. Eng

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“…c j x m y n j ¼ 1 þ ðm þ nÞ 2 þ m þ 3n 2 ðm ¼ 0;1; 2; · · · ; 10 n ¼ 0;1; 2; · · · ; 10Þ; (16) where c is the vertex curvature, k is the conic constant, and c j is the freeform coefficient. The process of optimization starts to optimize the surface with a rotationally symmetric aspheric type, and then the aspheric surface is converted to the XY-polynomial type through a fitting algorithm for the final stage of optimization.…”

Section: Optimizingmentioning

confidence: 99%

“…11 However, few design methods have been proposed for off-axis EUV lithographic objective. [14][15][16] But because these designs are based on the imaging principle of the coaxial optical system, these design methods cannot be used to directly design an off-axis system. [14][15][16] But because these designs are based on the imaging principle of the coaxial optical system, these design methods cannot be used to directly design an off-axis system.…”

Section: Introductionmentioning

confidence: 99%

Design method of off-axis extreme ultraviolet lithographic objective system with a direct tilt process

Liu

Cao

2015

Opt. Eng

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Downloaded From: http://opticalengineering.spiedigitallibrary.org/ on 08/17/2015 Terms of Use: http://spiedigitallibrary.org/ss/TermsOfUse.aspxAbstract. An off-axis extreme ultraviolet (EUV) lithographic objective can achieve a high numerical aperture (NA) beyond 0.33 with only six mirrors due to the efficient separation of the ray path, which greatly improves the resolution and energy utilization. A method is developed to design an off-axis lithographic objective with six mirrors. The method starts with a coaxial system with ray vignetting caused by increase of the NA. To avoid the ray vignetting, a reasonable range of solution for the tilt angle of each mirror is determined by real ray calculation. A set of optimal solutions for tilt angles of mirrors, which corresponds to the minimal composite root-mean-square wavefront error, is found from the reasonable ranges of solutions by a search program. In this way, an initial off-axis configuration without ray vignetting can be directly obtained and it is suitable for further optimization. To demonstrate the practicability of the method, an off-axis design example is given which shows that the presented method provides an efficient process to get to initial configuration for off-axis EUV lithographic objective with six mirrors. Downloaded From: http://opticalengineering.spiedigitallibrary.org/ on 08/17/2015 Terms of Use: http://spiedigitallibrary.org/ss/TermsOfUse.aspx Zhen Cao received his BS degree in optoelectronic information engineering from Xi'an Technological University in 2008. He is currently a PhD candidate directed by Prof. Yanqiu Li in the School of Optoelectronics at Beijing institute of Technology. His current interests include the optical system design for EUVL. Optical Engineering 075102-7 July 2015 • Vol. 54(7) Liu, Li, and Cao: Design method of off-axis extreme ultraviolet lithographic objective system. . . Downloaded From: http://opticalengineering.spiedigitallibrary.org/ on 08/17/2015 Terms of Use: http://spiedigitallibrary.org/ss/TermsOfUse.aspx

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“…Compared with the optical system of Excimer Laser lithographic facility [2] , the objective researched in this article especially points on the large exposure square. Figure.1 is the original large field objective lens designed by Glatzel [3] in 1980s.…”

Section: Introductionmentioning

confidence: 99%

Design of a projection objective with high numeric aperture and large view field

Liu

Gao

et al. 2014

SPIE Proceedings

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As the primary facility for the manufacturing of integrated circuit(IC), and MEMS devices [1] , the lithographic equipment's improvement is restricted by the projection objective which can decide the capacity of the image transmission of the facility and make the facility be capable of reaching the higher precision or beyond. On the basis of the function, increasing the numeric aperture is coupled with the raising of resolution of the projection objective. In this paper, a design of a projection objective with high numeric aperture and large view field for I-line lithography is proposed. Owning a dual-telecentric structure this optical system owns an angular magnification of -1.25, an effective image field of 90×90mm and an image numeric aperture of 0.2. Two aspheric surfaces are adopted in this projection objective to enhance the quality of imaging that will insure the field curvature lower than a half of the DOF, restrict the distortion lower than 5 σ ± and make the MTF approximate the diffraction limits.

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Grouping design method with real ray tracing model for extreme ultraviolet lithographic objective

Cited by 12 publications

References 10 publications

Illumination system with freeform fly’s eye to generate pixelated pupil prescribed by source-mask optimization in extreme ultraviolet lithography

Illumination system with freeform fly’s eye to generate pixelated pupil prescribed by source-mask optimization in extreme ultraviolet lithography

Design method of off-axis extreme ultraviolet lithographic objective system with a direct tilt process

Design of a projection objective with high numeric aperture and large view field

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