Deposited debris characteristics and its reduction of a laser-produced plasma extreme ultraviolet source using a colloidal tin dioxide jet target

Abstract

Debris characteristics and their reduction have been investigated for a laser-produced plasma extreme ultraviolet source by using a colloidal jet target containing tin dioxide nanoparticles. The amounts of deposited debris on a witness plate were determined by total laser energy irradiated onto a target. In situ low-temperature (100°C) heating of a plate was effective to reduce the amounts of deposited debris, since colloidal debris was easily vaporized by the heat.

EUV and debris characteristics of a laser-plasma tin dioxide nano-particle colloidal jet target

“…Although the evaluated deposition rate was approximately a half of the measured one, it is natural to consider that the vaporized volume would have been enhanced by approximately a factor of two by the target heating. These results indicate that the deposited debris amount was not determined by the plasma regulation verified by double pulse laser irradiation [9], but more simply by a vaporized amount of the target determined by the irradiated laser energy [11]. …”

“…Electromagnetic methods may not be always effective for such non-charged debris. Time- deposited debris characteristics should, therefore, be investigated to construct realistic debris mitigation system [11].…”

Debris characteristics and mitigation of a laser plasma tin-contained liquid jet/droplet targets

“…Figure 5(a) shows a typical XPS spectrum of a silicon witness plate placed at a distance of 15 cm from the target without laser irradiation [12]. The O-1s and O-2s signals were originated from an oxidized layer of the silicon surface.…”

“…The amount of deposited debris on a silicon witness plate was simply determined by a total laser energy irradiated onto a target. In situ low-temperature heating of the witness plate was effective to reduce the amount of deposited debris [12]. Room-temperature photon processing using an incoherent vacuum ultraviolet (VUV) excimer lamp at 126 nm deoxidized a deposited tin oxide layer.…”

Steady-State and Time-Dependent LPP Modeling

“…A range of mitigation measures has been proposed including magnetic fields, plasma shutters, buffer gases, sacrificial layers, and combinations of these. In addition, the reduction of debris emission by target design has resulted in the proposed use of masslimited targets, targets containing nanoparticles (Kaku et al, 2008), cavity targets (Ueno et al, 2007), etc. However, it is most likely that a combination of these measures will be required in addition to a cleaning routine based on scavenger gases flushed through the system.…”