We describe studies of the debris produced from a high-repetition-rate laser plasma EUVL source based on the mass-limited target concept. hi particular, we are developing mass-limited target designs based on complex targets containing tin. Comprehensive analysis of witness-plate detection techniques can reveal many interesting details of the interaction regime, and the impact of the debris. These techniques include Optical Microscopy, Scanning Electron Microscopy, Atomic Force Microscopy, X-ray Photoelectron Spectroscopy, Auger Electron Spectroscopy, and Auger Electron Microscopy. We also describe developments of the repeller field concept of debris inhibition. This technique uses electrostatic fields to reduce the flux of plasma ions impinging on the EUV collimating optics. Here, the first measurements of debris mitigation of a tin-doped target are described, and comparisons with earlier measurements of the impact of repeller fields on ion emission from a mass-limited water-droplet target are made.

One of the key leverage factors in determining the viability of laser-plasma sources for EUVL is the conversion efficiency of laser light to EUV emission in the 13-nm region. We describe experiments and theoretical calculations on a mass-limited laser target design using tin that offers high conversion efficiency.

A compact laser-produced plasma x-ray source radiates 1 nm x rays with an average power of 24 W in 2π steradians. The x-ray conversion efficiency is 9% of the laser power delivered on target. The 300 W laser power is generated by a compact diode-pumped, solid-state Nd:YAG laser system. The point source x-ray radiation is collimated with a polycapillary optic to a parallel x-ray beam. The collimated plasma source (CPS) is used to demonstrate proximity x-ray lithography of 100 nm lines with a 16 μm gap between the mask and wafer. The CPS is optimized for integration with an x-ray stepper to provide a complete collimated plasma lithography exposure tool for the manufacture of high-speed GaAs devices.

The most efficient use of radiation point sources for x-ray lithography requires a collimator to capture a large fraction of spherically emitted radiation and deliver the rays with acceptable divergence properties. We describe an x-ray point source utilizing a polycapillary collimator. The optical performance of the collimator was measured and is described. Dense line-space patterns (∼100 nm lines) were printed in poly(methylmethacrylate) using a mask-wafer gap of 16 μm. Lithography results are consistent with modeling analysis.

A compact x-ray source radiates 24 Watts average power of 1nm x-rays in 2 (pi) steradians. The laser produced plasma x-ray source has a 300 W laser driver which is a compact, diode-pumped solid-state Nd:YAG laser system. The x-ray conversion efficiency is 9 percent of the laser power delivered on target. The x-ray source was used to demonstrate x-ray lithography of 75 nm lines. The x-ray source is optimized for integration with a x-ray stepper to provide a complete x-ray lithography exposure tool for the manufacture of high-speed GaAs devices.

X-ray spectra of Cu plasmas at the focus of a four-beam, solid-state diode-pumped laser have been recorded. This laser-plasma X-ray source is being developed for JMAR's lithography systems aimed at high- performance semiconductor integrated circuits. The unique simultaneous overlay of the four sub-nanosecond laser beams at 300 Hertz produces a bright, point-plasma X-ray source. PIN diode measurements of the X-ray output indicate that the conversion efficiency (ratio of X-ray emission energy into 2π steradians to incident laser energy) was approximately 9 percent with average X-ray power yields of greater than 10 Watts. Spectra were recorded on calibrated Kodak DEF film in a curved-crystal spectrograph. A KAP crystal (2d = 26.6 Angstroms) was used to disperse the 900 eV to 3000 eV spectral energies onto the film. Preliminary examination of the films indicated the existence of Cu and Cu XX ionization states. Additional spectra as a function of laser input power were also recorded to investigate potential changes in X-ray yields. These films are currently being analyzed. The analysis of the spectra provide absolute line and continuum intensities, and total X-ray output in the measured spectral range.

Summary form only given. A compact laser produced plasma X-ray source generates 24 Watts average power of 1.1 nm X-rays in 2/spl pi/ steradians. The laser-plasma source is driven by a compact, diode-pumped, solid-state 300 Watt Nd:YAG laser system.

Laser to x-ray conversion efficiencies from solid targets irradiated by KrF laser pulses of wavelength 248 nm are measured. A 16-bit front illuminated open electrode 1024×256 pixel x-ray CCD camera working in single photon counting mode is used to record the x-ray output from Al, Cl, Ag, and Ti emitting in the 1.5-4.5 keV photon energy range. X-ray conversion efficiencies up to values of ~0.2{%} (2π sr)-1 are obtained with pulses of duration 2 ps irradiating the targets at 12 Hz with peak irradiance of 1.9×1016 W cm-2.

Mass spectrometry identifies atomic and molecular species and relative concentrations in a given atmosphere. The analysis of the composition and of the atmosphere variations in a batch system, that contains a suspension of yeast cells or lymphocytes, allows to identify and to track cell metabolic processes. Such a technique has proven to be efficient in radiobiology experiments to investigate soft X-ray non-nuclear damages, as complementary to other physical and chemical assessments.

A high power picosecond soft x-ray source is generated by a compact, modular, diode pumped solid state laser BriteLightTM. Three x-ray source version are constructed from laser modules with increasing power. The power of the x-ray sources is tailored to potential applications. The building block of such a modular system is a 3 Watt x-ray power source with 1.1 keV x-ray photon energy. The laser system is very compact with dimensions of 4 ft X 3 ft X 1 fit. It is composed of a laser master oscillator, pre-amplifier and one power amplifier. A four laser amplifier system was also constructed in order to generate 12 W of x-rays for application to x-ray lithography.

The characteristics of an extreme-ultraviolet (XUV) continuum light source and its application to a dual-laser plasma (DLP) photoabsorption experiment are described. The continuum emitting plasma was formed by focusing a 7 ps, 248 nm, 15 mJ laser pulse onto a number of selected targets known to be good XUV continuum emitters (Sm, W, Au and Pb), while the second absorbing plasma was produced by a 15 ns, 1064 nm, 300 mJ pulse. The duration of the continuum emission for these plasmas has a mean value of ~150 ps, but depends on both the target material and the picosecond laser pulse energy. Using this picosecond DLP set-up we have been able to measure the photoabsorption spectrum of an actinide ion (thorium) for the first time.

Collimating of the x-ray beam is essential to point source proximity x-ray lithography for controlling radial magnification and increasing the beam intensity. Polycapillary optic collimators were developed to meet the challenges of point source proximity x-ray lithography. Sophisticated modeling software was developed for design and optimization of polycapillary collimators to meet specific requirements. Using this software, a highly efficient collimator was designed to deliver a well-collimated beam centered at 1.1 keV for a 20 mm X 20 mm field. The collimator was constructed and was tested with both an electron bombardment source and a laser generated plasma source. The design goals of intensity gain and divergence controls have been achieved. The intensity variation within the printing field can be less than 2%.

The 5-50-eV spectral range appears to be absent from the planned third generation synchrotron radiation sources (SRS) and the science requiring this radiation can be jeopardized once the second generation SRS light sources are switched off worldwide. Molecular photochemistry, photobiology, atomic physics, solid-state physics are but a few sciences requiring powerful VUV sources. We demonstrate that a compact, laser heated plasma light source can generate efficiently radiation in this spectral region, and that this radiation can be coupled very efficiently from the plasma to the exposure cell, by three simple VUV beam-lines, each providing a different spectral bandwidth.

An x-ray power of 2.8 Watts at the 1 nm x-ray lithography wavelength was generated by a copper plasma formed by a single laser beam focused to an intensity of >10(14) W/cm(2) on a copper tape target. The all solid state Britelight(TM) YAG laser has 700 ps pulse duration, 300 Hz pulse repetition rate, average power of 75 Watts, and <2 times diffraction limited beam quality at the fundamental 1.064 mu m wavelength. The single beam laser system has a master oscillator, a preamplifier and one power amplifier, all diode pumped. Measurements confirmed negligible copper vapor debris at 8 cm from the laser-plasma source with atmospheric pressure He gas and modest gas flow. The point source x-ray radiation was collimated with either a polycapillary or grazing mirror collimator. The near-parallel beam of x-rays has good divergence both globally (0.5mrad) and locally (<3 mad), good uniformity (2% achievable goal) and large uniform field size (20 mm x 20 mm full field and 25mm x 36mm scanning system). High-resolution lithography was performed for the first time with collimated I nm point source x-rays. A power scaling system is being built with eight amplifred beams in parallel on the x-ray target, and is expected to achieve 24-30 Watts of x-rays. A 16 beam laser plasma x-ray lithography system could achieve a throughput of 24 wafer levels per hour using 300 mm diameter wafers.

A novel imaging low-energy x-ray fluorescence spectrometer with no moving parts, based on a microchannel plate relay optic and an open electrode charge-coupled device with good sub-keV quantum efficiency, is described. Results from a proof of principle experiment using the Rutherford Appleton Laboratory picosecond pulsed laser plasma x-ray source are described and the performance limits of the spectrometer explored. Copyright © 1999 John Wiley & Sons, Ltd.

A new technique of Focused Ion Beam (FIB) microscopy-nanomachining is proposed for life sciences. Its performances are compared with those of currently available ultramicroscopy apparatuses. Ultra-high resolution tridimensional tomography can be performed on whole cells without preparation. This can be achieved by sequentially etching layers of material and subsequently viewing the result of the operation under a different perspective. Very fast imaging times (minutes) allow quasi real time microscopy. The complementary technique of nano-biology can be performed on the same apparatus. The use of the ion beam allows to imaging both the surface and the inner part of the sample along any desired plane that can be chosen while the observation is on.

A large volume excimer laser, HERCULES, has been successfully applied as pump for a soft X-ray plasma source. The laser pulse duration has been varied from the natural value of 120 ns down to 10 ns, reaching different emission spectra from the plasma which have resulted to be optimum for different applications of the plasma source itself.Some experimental results on the applications of the source to different fields (X-ray microscopy, radio-biology, X-ray micro-lithography, basic plasma physics research) are presented; the choice of the best laser parameters in relation to the applications of the plasma source are also discussed.

High-resolution commercial photomasks and x-ray masks are at present manufactured by a multistep process which involves the use of etching. This route imposes a limitation on the resolution that can be achieved. We describe here a new approach to the fabrication of x-ray masks involving the use of organometallic compounds which undergo direct conversion to metal under the influence of electron beam irradiation. This approach permits fabrication of both x-ray masks and extreme ultraviolet masks in essentially a single processing step. The attainable resolution is unaffected by any limitation incurred by etching processes and is dependent only on such factors as electron scattering and electron beam diameter. We describe here the production of a gold x-ray mask, which was used in conjunction with a compact laser plasma source to demonstrate the lithographic process.

Two laboratory scale x-ray microscopes using laser generated plasma sources are being developed at King's College. One system uses dark field imaging while the other is a scanning x-ray microscope and progress with both is described. In particular, preliminary results from an extensive characterization of the laser plasma source at the Lasers for Science Facility, CLRC Rutherford Appleton Laboratory, are discussed. This characterization has shown that the source is eminently suitable for x-ray microscopy.

A picosecond excimer laser-plasma source has been constructed which generates an x-ray average power of 2.2 Watt and 1.4 Watt at the wavelengths required for proximity x-ray lithography: 1.4 nm (steel target) and 1 nm (copper target), respectively. The plasma source could be scaled to the 50 - 75 W x-ray average power required for industrial lithographic production by scaling the total average power of the commercial excimer laser system up to 1 kW. The 1 nm x-ray source is used to micromachine a 2.5 THz microwave waveguide-cavity package with a 48 micrometers deep, 3D structure, using the LIGA technique.