Demonstration of a foil trap technique to eliminate laser plasma atomic debris and small particulates

Abstract

A novel method of filtering out atoms and small particulates, emitted from a laser plasma EUV radiation source, has been developed and experimentally characterized. The method consists of elimination of debris species by an optically transparent assembly of foils positioned in a buffer gas environment near the source. A high trapping efficiency is achieved due to retardation and scattering of particles in the gas and subsequent deposition on the foils. The method imposes no limitations of the radiation acceptance angle. The foil trap technique, a debris suppression method universally applicable for different EUVL radiation sources, has been investigated in combination with a fast rotating laser plasma target. A target unit with a disk edge velocity of up to 500 rn/s enabling nearly full elimination of large particulates, served as a source of different debris components for experiments on foil trapping atoms and sub-micron particulates. An integrated suppression coefficient of 500 has been measured for debris with sizes of up to a micrometer using a pilot trap cooled down to -90 °C. Extrapolation of this data to conditions when debris of sub-micron size only is produced, resulted in a suppression coefficient of 2000.

Characterization and optimization of the laser-produced plasma EUV source at 13.5 nm based on a double-stream Xe/He gas puff target

“…EUV metrology growth should keep up with the development of other EUV technologies. To address these problems, debris-free sources and droplet mitigation systems are under construction for EUV metrology purposes [5][6][7][8][9][10][11][12][13]. Nevertheless, much work remains to be done in this field.…”

Numerical modeling of tin jet motion after interaction with laser pulse

“…Таким образом, математическая модель состоит из эволюционного уравнения на фазовую долю (1), уравнения непрерывности (3) и уравнения движения (4). Отметим, что необходимым условием является ортогональность скорости сжатия (2) границе раздела фаз (интерфейсу).…”

“…Так, например, в плазменных источниках капли могут возникать в результате фрагментации струи под воздействием импульсов давления плазмы. Для оптимальной работы источника необходимо подавлять потоки капель, поэтому разрабатываются специальные механические системы защиты [4,5], для проектирования которых необходимо знать угловое и энергетическое распределение потоков жидкого вещества.…”

Characterization of collector optic material samples before and after exposure in laser produced plasma and discharge produced plasma extreme ultraviolet sources

“…The ellipsoid pinch geometry is ϳ1.5 mmϫ 0.5 mm. A foil trap-based debris mitigation tool with Ar buffer gas curtain, 14 which is similar to a collimator consisting of flat metal pieces placed with their normal direction perpendicular to the light path, is applied radially to reduce particle transfer from the pinch to the collector optics. Furthermore, an Ar buffer gas curtain flows through the debris tool at a high flow rate to enhance the scattering possibility for ejected particles from the pinch plasma.…”