Design and optimization of collectors for extreme ultraviolet lithography

Zocchi, Fabio E.; Buratti, Enrico; Rigato, V.

doi:10.1117/12.656417

Cited by 13 publications

(12 citation statements)

References 13 publications

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“…It can be shown that the total reflectivity is maximized when the two grazing incidence angles [15], and thus the reflectivity of the two reflections, are equal, at least when the coating reflectivity is a strictly monotonic function of the grazing incidence angle. This condition can not be satisfied for all rays in a type I Wolter design.…”

Section: Introductionmentioning

confidence: 98%

An alternative optical design for x-ray telescopes

Zocchi

Vernani

2007

SPIE Proceedings

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A two-reflection optical design for nested X-ray telescopes is described in which the two grazing incidence angles are equal for each ray collected by each mirror, so that the total reflectivity is maximized. A specific design is discussed and its optical performances are compared to a reference type I Wolter optics. In the selected design scenario, a 16% reduction in the number of mirror shells and a 6% increase of the effective area between 1 keV and 10 keV is achieved, along with a small 2.6% decrease of the angular resolution over 12 armin field of view.

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Section: Introductionmentioning

confidence: 98%

An alternative optical design for x-ray telescopes

Zocchi

Vernani

2007

SPIE Proceedings

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“…The wavelength of 13.5nm was chosen because it was found that Mo/Si multilayer mirrors could be fabricated with very high reflectivity (~70%) at this wavelength and stable in time [5][6][7][8]. Many of the sources under consideration use radiation from multicharged xenon ions [9,10] excited by a large number of sources like: the laser produced plasma [11,12], the synchrotron wiggler, Z-pinch [13], plasma focus [14] and capillary discharge produced plasma [9,10,15].…”

Section: Introductionmentioning

confidence: 99%

Observations and analysis of extreme ultraviolet emission by capillary discharge with Xe as target

Zhao

Zhi-liang

et al. 2010

2010 Academic Symposium on Optoelectronics and Microelectronics Technology and 10th Chinese-Russian Symposium on Laser Physics

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The first capillary discharge produced plasma extreme ultraviolet source has been started in China. Fundamental characteristics of DPP including current, Xe gas pressure, extreme ultraviolet energy and spectrum in extreme ultraviolet region have been studied. A high voltage power source is employed, which voltage can be changed from 20kV to 30kV, and the current is from 25kA to 45kA with a FWHM of 120ns. The high voltage is loaded between the capillary which is 3mm in diameter and 12mm in length by injected Xe gas to achieve extreme ultraviolet radiation mostly in the region 10nm~18nm developed in framework of an extreme ultraviolet lithograph program. It is founded that the in-band (13.5nm, 2% bandwidth) energy is increasing with decreasing Xe gas pressure and/or increasing the current in the region 5~10Pa and 25kA~45kA.And 0.56J/2π sr/pulse energy (13.5nm, 2% bandwidth) can be got when the input energy is 47.7J, and the conversion efficiency is 0.56%.

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“…Collectors that have been implemented in EUVL tools today are Wolter Type1 designs that have been adapted from x-ray telescopes [2]. However, these designs use a long format suitable for imaging distant light sources.…”

Section: Introductionmentioning

confidence: 99%

“…However, these designs use a long format suitable for imaging distant light sources. As applied to industrial equipment and very bright nearby sources, the Wolter collectors tend to be expensive and require significant debris shielding and integrated cooling solutions due to the source proximity and length of the collector shells [2].…”

Section: Introductionmentioning

confidence: 99%

Low-cost EUV collector development: design, process, and fabrication

et al. 2007

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Cost of ownership (COO) is an area of concern that may limit the adoption and usage of Extreme Ultraviolet Lithography (EUVL). One of the key optical components that contribute to the COO budget is the collector. The collectors being fabricated today are based on existing x-ray optic design and fabrication processes. The main contributors to collector COO are fabrication cost and lifetime. We present experimental data and optical modeling to demonstrate a roadmap for optimized efficiency and a possible approach for significant reduction in collector COO. Current state of the art collectors are based on a Wolter type-1 design and have been adapted from x-ray telescopes. The Wolter collector design uses a long format that is suitable for imaging distant light sources such as stars. As applied to industrial equipment and very bright nearby sources, however, a Wolter collector tends to be expensive and requires significant debris shielding and integrated cooling solutions due to the source proximity and length of the collector shells.Three collector concepts are discussed in this work. The elliptical collector that has been used as a test bed to demonstrate alternative cost effective fabrication method has been optimized for collection efficiency. However, this fabrication method can be applied to other optical designs as well. The number of shells and their design may be modified to increase the collection efficiency and to accommodate different EUV sourcesThe fabrication process used in this work starts with a glass mandrel, which is elliptical on the inside. A seed layer is coated on the inside of the glass mandrel, which is then followed by electroplating nickel or nickel alloys. The inside/exposed surface of the electroformed nickel is then diamond turned and/or polished to meet the figure and finish requirements for the particular shell and finally coated with Ru or a multilayer film depending on the angle of incidence of EUV light. Finally the collector shell is released from the inside surface of the mandrel.There are several potential cost and fabrication advantages to this process. There is flexibility in the choice of material for producing the mandrel -this allows for optimizing the cost of fabrication of the mandrel. Moreover, since the final surface and figure of the collector optic can be modified, after electroforming the optic, the mandrel, in principle does not have a limited lifetime. Finally, the mandrel provides mechanical support to the electroformed optic throughout the fabrication process, thereby reducing deformation of the optic during diamond turning and/or polishing and coating.The optical design, optimization of collection efficiency, fabrication and characterization results is discussed in this work.

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Design and optimization of collectors for extreme ultraviolet lithography

Cited by 13 publications

References 13 publications

An alternative optical design for x-ray telescopes

An alternative optical design for x-ray telescopes

Observations and analysis of extreme ultraviolet emission by capillary discharge with Xe as target

Low-cost EUV collector development: design, process, and fabrication

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