EUV Labs (Russia)

A sealed compact system based on two series-connected magnetohydrodynamic pumps for pumping liquid metal media with an operating temperature as high as 450°C is described. The system is designed to produce a renewable target in the form of a liquid lithium jet in a pulsed-repetition rate source of extreme ultraviolet (EUV) radiation based on laser plasma. The system provides a head pressure of 2 bar and a flow rate of up to 80 cm3/s and is characterized by reliability, simplicity of design, the absence of moving parts, convenient handling, and the ability to pump aggressive conductive liquids. The system is easily scalable in both the head pressure and the flow rate. The long-term operation of the system has been demonstrated in a laser-produced plasma EUV source, where it provided a jet velocity of up to 22 m/s.

The progress of EUVL and the introduction of HVM scanners demands advanced actinic metrology especially for the EUV mask supply chain. For stand alone field use reliable metrology sources for EUV inband emission around 13.5 nm are critically needed. For nanometer resolution the effective "inband brightness" is extremely important. Laser produced EUV sources (LPP) are cost effective with efficient energy use thus providing a reliable approach for real-life industrial applications. However, apart from the Cymer/ASML LPP scanner source no such source is available. One reason is that realizing a reliable tin droplet target is beyond the technical and financial scope of a metrology source. In this paper, we propose a path to make industrial laser produced plasma based EUV sources reliable and with easy renewable targets a reality.

A centrifugal pump for transmitting molten metals and other liquids with a working temperature as high as 380°C is described. The pump ensures a head pressure of up to 9 atm and a flow rate of up to 1 m3/h. A rotary torque is transmitted from the electric motor to the turbine of the pump by means of the alternatingpole magnetic coupling. The compactness of the design is ensured by a vacuum gap between the “hot” inner and “cold” outer half-couplings. The pump is applied in high-power X-ray and extreme ultraviolet sources for forming liquid tin jets used as updated electrodes (in sources based on a discharge plasma) or a updated target (in sources based on a laser plasma), where it ensures velocities of tin jets of up to 15 m/s.