Tin-fueled high-repetition-rate Z-pinch EUV source for semiconductor lithography

Gas-discharge Z-pinch plasma was researched for the sake of EUV source development for semiconductor lithography. A low-inductance, high-repetition-rate magnetic pulsed compression generator was coupled with a discharge electrode. In order to fulfill the requirements from the semiconductor lithography exposure tool, up to 8 kHz of discharge repetition frequency was tested with 15 J/pulse of energy storage. In addition to the improvement of electrical energy input, it is necessary to increase conversion efficiency (CE) from electrical to in-band (within 2 % bandwidth around λ=13.5 nm) radiation energy. Therefore tin hydride gas (SnH4) was utilized in this research. Radiation characteristics were investigated through the radiation measurements. In-band radiation power reached 700 W/2πsr/2%BW at 8 kHz, with plasma size of φ0.75×L4.6 mm and CE of 1.2 %.