Laser-plasma x-ray source using gas-target mixed fine particle

We are developing laser plasma x-ray source for the extreme UV lithography. Our main idea is than fine particles, which sizes ar much smaller than the laser focal spot size, are used for the target of LPS. It is possible that this method has the higher x-ray conversion efficiency and low debris effect. Before the verification of this idea, the characteristics of LPS using the only gas puff target were investigated and tried the 100 Hz gas puff continuous operation until 106 shots. In this operation, the long- term stability of the x-ray signal from 105 shots to 106 shots was about +/- 8 percent. In order to confirm our idea, we have selected SnO2 fine particle that had a strong peak at 13.8 nm. It has found that the target of the gas mixed SnO2 fine particle had two times higher x-ray intensity than the only Xe gas target at 13.6-14.0 nm. Therefore, it seems suitable for the Mo/Si multi-layer mirror system.