We have demonstrated ablation of holes with diameter as small as 82 nm in polymethyl methacrylate (PMMA) by
focusing the output of a capillary discharge soft x-ay laser with a Fresnel zone plate. We also report the first
demonstration of laser induced breakdown spectroscopy with soft x-ray laser light.
The implementation of a Laser Produced Plasma Extreme Ultra-Violet (LPP EUV) source requires a high-power laser focused onto a target. In order to minimize the required laser input power the target material must have a high conversion efficiency to 13.5 nanometer radiation. Ideally, a pulsed laser is used and the target should be delivered in small uniform volumes to a point in space at high repetition rates. The small volumes minimize the amount of debris, the high repetition rates enable higher power systems and the free space delivery alleviates thermal issues and allows large collection angles. It has been demonstrated that lithium and tin have very high conversion efficiencies and system solutions exist to use these materials. In this paper we describe the requirements and performance of a liquid metal micro-droplet target generator capable of dispensing both lithium and tin. Finally it is shown that the current generator performance is sufficient to support stable source operation.
We have demonstrated a new electron-impact hard-x-ray source based on a liquid-metal-jet anode in a proof-of-principle experiment. Initial calculations show that this new anode concept potentially allows a >100x increase in source brightness compared to today's compact hard-x-ray sources. In this paper we report on the scale up of the system to medium electron-beam power resulting in a brightness comparable to current state-of-the-art sources. The upgraded system combines a ~20-μm diameter liquid-tin jet operating at ~60 m/s with a 50 kV, 600 W electron beam focused to ~150 μm FWHM. We describe the properties of the current system, experimental results, as well as a brief discussion of key issues for future high-power scaling.
We describe a novel electron-impact x-ray source based on a high-speed liquid-metal-jet anode. Thermal power load calculations indicate that this new anode concept potentially could increase the achievable brightness in compact electron-impact x-ray sources by more than a factor 100 compared to current state-of-the-art rotating-anode or microfocus sources. A first, successful, low-power proof-of-principle experiment is described and the feasibility of scaling to high-brightness and high-power operation is discussed. Some possible applications that would benefit from such an increase in brightness are also briefly described.
We introduce a novel electron-impact x-ray source based on a high-speed liquid-metal-jet anode. Basic thermal power load calculations indicate that this new anode concept potentially could increase the achievable brightness in compact electron-impact x-ray sources by more than a factor 100 compared to current state-of-the-art rotating-anode or micro-focus sources. A first, successful, low-power proof-of-principle experiment is described and the feasibility of scaling to high-brightness and high-power operation is discussed. Some possible applications that would benefit from such an increase in brightness are also briefly described.
The liquid-xenon-jet laser-plasma source is one of the extreme-ultraviolet (EUV) source technologies under development for EUV lithography. This paper presents some recent improvements of the technology, including the ability to operate a stable plasma at a distance of 50 mm from the nozzle, the first positive mirror-lifetime results, and improved laser-to-EUV conversion efficiency of 0.75 percent at lambda equals 13.45 nm.
The liquid-xenon-jet laser-plasma source is one of the
extreme-ultraviolet (EUV) source technologies under development
for EUV lithography. This paper discuss the basic, demanding,
requirements of a source for EUV lithography including high
in-band EUV power, absence of mirror contamination and high
stability. It is further discussed how the liquid-xenon-jet can
meet these requirements, and specifically how the ability to
operate the plasma far from any mechanical details such as the
nozzle will facilitate high power operation with low resulting
mirror degradation. Furthermore, a new laser-to-EUV conversion
efficiency result of 0.55%/(2%BW 2pisr) at lambda=13.45 nm is presented together with a detailed
description of the method for calibrated EUV-power measurement.
In this paper the speed of microscopic droplets used as targets for laser-plasma soft x-ray generation is investigated. The speed is measured for a variety of liquids with different hydrodynamic properties and at different pressures. A theoretical model is then adapted to predict the speed of the jet, given the applied pressure and the physical properties of the liquid. Since certain liquids with low surface tension and cryogenic liquids are interesting for laser-plasma generation, obtaining a model for the speed of the liquid is important, as the speed cannot be easily measured for these liquids.
We describe a laser-plasma source based on a cryogenic xenon liquid-jet target suitable for extreme ultraviolet (EUV) projection lithography. Recent improvements in the stability of the xenon jet allows efficient laser-plasma operation several millimeters away from the nozzle orifice. We present the first preliminary laser-to-EUV conversion efficiencies, although under non-optimized conditions, for the source.
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