An optimization of conditions for excitation of xenon laser plasma in a source of extreme ultraviolet radiation for nanolithography in order to increase its efficiency

For Russian citation (Opticheskii Zhurnal):

Буторин П.С., Калмыков С.Г. Оптимизация условий возбуждения ксеноновой лазерной плазмы в источнике экстремального ультрафиолетового излучения для нанолитографии с целью повышения его эффективности // Оптический журнал. 2024. Т. 91. № 5. С. 95–104. http://doi.org/10.17586/1023-5086-2024-91-05-95-104

Butorin P.S., Kalmykov S.G. An optimization of conditions for excitation of xenon laser plasma in a source of extreme ultraviolet radiation for nanolithography in order to increase its efficiency [in Russian] // Opticheskii Zhurnal. 2024. V. 91. № 5. P. 95–104. http://doi.org/10.17586/1023-5086-2024-91-05-95-104

For citation (Journal of Optical Technology):

Abstract:

Subject of study. Laser plasma excited by the xenon gas jet of a target. Goal of the work. Increasing the output of extreme ultraviolet radiation from such a plasma, used as a source of working radiation in a new branch of lithography with a wavelength near 11.2 nm, to a level that meets the requirements of industrial production. Method. The main method used was to change the diameter of the laser beam by moving Xe of the gas-jet target along its axis, which led to a change in the size of the area of interaction of the beam with the target and, accordingly, to a change in the size of the laser spark. The intensity of plasma radiation with wavelengths of 11.2 and 13.5 nm was measured using a surfacebarrier Si photosensor and a Bragg mirror, and the laser radiation energy absorbed by the plasma was also measured. Main results. When the diameter of the laser beam illuminating the target increases from 46 to 344 μm, the energy emitted in the extreme ultraviolet range increases approximately
5 times. In the found irradiation mode, the efficiency of conversion of laser radiation into radiation with a wavelength of 11.2 nm was 3.9%. Recent measurements of the plasma lifetime have shown that it depends on the size of the plasma and in a number of experiments turns out to be significantly shorter than the laser pulse, which makes it possible to use this parameter (plasma lifetime) as an optimization parameter when choosing the laser pulse duration. Practical significance. The results obtained demonstrate a record efficiency for laser-plasma radiation sources with a gas target for the conversion of laser pulse energy into the energy of extreme ultraviolet radiation, which opens up the prospect of using such a source in the industrial production of microcircuits.

Keywords:

laser plasma, extreme ultraviolet, conversion factor, nanolithography, laser breakdown

Acknowledgements:

this work was carried out in accordance with the State Assignment of Ioffe Institute (№ 0040-2019-0001)

OCIS codes: 140.3440, 350.5400, 260.7200

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