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The SWIFTS integrated waveguide device (Stationary Wave Integrated Transform Spectrometer) has been designed on top of a 1D parallel array of 50-nm-width single stripe Superconducting Nanowire Single Photon Detectors (SNSPD). Colored light, around 1.55-μm wavelengths, is introduced inside PE-CVD deposited and patterned Si3N4 monomode rib waveguides, in order to produce a counter-propagative stationary wave over the Nanowire array. Optical power losses are reported, mainly due to waveguide sidewall roughness scattering, end-fire fiber coupling and mode coupling mismatch. Simulations and measurements over waveguide bending, coupling and roughness quantify the loss contributions of the different factors. E-beam lithography has been re-optimized on 4-inch sapphire and NbN passivating nano-layers added for elaborating SWIFTS devices with 24 Nanowires each of 50-nm widths, capable of directly sampling the stationary wave profile. Process compatibility has been demonstrated, thanks to the MgO layer protecting NbN Nanowires before SiN deposition. Each SNSPD should operate separately at 4K in the single photon counting regime for sampling the guided standing wave, introduced by the high precision mechanical alignment of a fiber in the test set-up.

International audience; Radiative shocks can be produced in gases using high-energy lasers. As the electron density may be higher than the critical density for visible light, radiography with soft x-ray radiation becomes very promising technique to probe these shocks. Feasibility of this method has been proven employing zinc soft x-ray laser at 21.2 nm as backlighter. The experiment has shown high requirements on quality of the imaging optics and windows of the gas filled cell.

International audience; This report presents the results from experiments at PALS Centre using a Zn X-ray laser with the pulse length of 0.15 ns and the wavelength of 21.2 nm, working in single or double pass regime with the output energy of 0.4 mJ or 4 mJ per pulse, respectively. The current X-ray laser was experimentally examined to obtain its temporal coherence and spectral width using a path-difference interferometer. The double pass regime shows that QSS plasma based source-amplifier is promising for "short" fs soft X-ray pulses. The X-ray laser is commonly used for user's experiments. Its advantages can be shown in applications such as probing of dense plasmas (up to 2.5 x 10(24) cm(-3)) or single shot experiments (4 x 10(14) photons/pulse). The simple technique based on Talbot effect was used to obtain the gradients of electron densities of line plasmas produced under conditions corresponding to XRL's amplifiers operating in TCE and QSS regime. To investigate radiative shock wave in laboratory is challenging in aspects of the optimization of experimental parameters. Due to the high electron density (10(22) cm(-3)) produced in the gas medium propagated by the shock wave, the velocity of the shock wave, and the absorption losses on optical elements, it is necessary to use the energetic single shot probe.

The challenge of the Integrated Circuit size reducing leads to the development of new processes for future years. In the lithography domain, since several years, the EUV Lithography appears as a possible technique to reach the ITRS roadmap requirements. The EUV interferometry Lithography is still nowadays an efficient way to study and improve the EUV resist behaviors. Although the interferometer principle seems to be obvious, the optimization of its use is only reached regarding some huge constraints. In this work accurate numerical models and experimental studies have been developped. It shows that some undesirable effects can reduce the interference region and disturb the contrast of the resist printed lines. The EUV light is identified as the first issue. The beam divergence of EUV light affects the contrast quality of the fringes. The photometry computation, taking into account the optimum angular source light width is then detailed. The second cause is the Fresnel diffraction of light due to boundaries of the grating windows. Its superimposition with diffraction orders induces a damage of local printed interferences. This phenomenon leads to an edge disturbance of the interference fringes. The third cause addressed is the decrease of the interference area by the position of the wafer out of the focal distance. Possible shadowing effects are also shown.

EUV lithography is expected to be inserted for the 32/22 nm nodes with possible extension below. EUV resist availability remains one of the main issues to be resolved. There is an urgent need to provide suitable tools to accelerate resist development and to achieve resolution, LER and sensitivity specifications simultaneously. An interferometer lithography tool offers advantages regarding conventional EUV exposure tool. It allows the evaluation of resists, free from the deficiencies of optics and mask which are limiting the achieved resolution. Traditionally, a dedicated beam line from a synchrotron, with limited access, is used as a light source in EUV interference lithography. This paper identifies the technology locks to develop a stand alone EUV interferometer using a compact EUV source. It will describe the theoretical solutions adopted and especially look at the feasibility according to available technologies. EUV sources available on the market have been evaluated in terms of power level, source size, spatial coherency, dose uniformity, accuracy, stability and reproducibility. According to the EUV source characteristics, several optic designs were studied (simple or double gratings). For each of these solutions, the source and collimation optic specifications have been determined. To reduce the exposure time, a new grating technology will also be presented allowing to significantly increasing the transmission system efficiency. The optical grating designs were studied to allow multi-pitch resolution print on the same exposure without any focus adjustment. Finally micro mechanical system supporting the gratings was studied integrating the issues due to vacuum environment, alignment capability, motion precision, automation and metrology to ensure the needed placement control between gratings and wafer. A similar study was carried out for the collimation-optics mechanical support which depends on the source characteristics.

In this work, we demonstrate a full process for fabricating high aspect ratio diffraction optics for extreme ultraviolet lithography. The transmissive optics consists in nanometer scale tungsten patterns standing on flat, ultrathin (100 nm) and highly transparent (>85% at 13.5 nm) silicon membranes (diameter of 1 mm). These tungsten patterns were achieved using an innovative pseudo-Bosch etching process based on an inductively coupled plasma ignited in a mixture of SF6 and C4F8. Circular ultra-thin Si membranes were fabricated through a state-of-the-art method using direct-bonding with thermal difference. The silicon membranes were sputter-coated with a few hundred nanometers (100-300 nm) of stress-controlled tungsten and a very thin layer of chromium. Nanoscale features were written in a thin resist layer by electron beam lithography and transferred onto tungsten by plasma etching of both the chromium hard mask and the tungsten layer. This etching process results in highly anisotropic tungsten features at room temperature. The homogeneity and the aspect ratio of the advanced pattern transfer on the membranes were characterized with scanning electron microscopy after focus ion beam milling. An aspect ratio of about 6 for 35 nm size pattern is successfully obtained on a 1 mm diameter 100 nm thick Si membrane. The whole fabrication process is fully compatible with standard industrial semiconductor technology.

EUV lithography is expected to be inserted for the 32 nm node and extended for the 22 nm and below. Phase shift masks (PSM) are evaluated as a possible option to push the resolution limit of the Extreme Ultra violet lithography. This paper will focus on designs and measurements of PSM implemented by etching into the Mo/Si multilayer (ML). The design and the technological developments to elaborate PSM by etching is described. Phase shift Sample (PSS) have been carried out to calibrate in "true operating conditions", i.e. through the measurement of the phase shift they produce on a reflected wavefront, at the wavelength (λ=13.5nm). The method of calibration have been investigated with a Fresnel bimirror interferometer installed on the PSI Swiss Light Source Synchrotron to measure directly the value of interest, i.e the optical phase.

The purpose of this article is to present a model which describes completely in a very simple way the physics of field-effect emission for an ensemble of tips located on a two-dimensional lateral resistive sheet. Given the well-known a and b parameters of each tips, the geometry of the mesh and the square resistance of the resistive sheet, we have determined exactly the voltage on each tip as a function of its position in the mesh and then calculated each current effectively emitted. Thanks to this theory some simple questions, as the following, could be answered: (1) When a specified number of tips is needed, and the mesh geometry fixed, where do we have to put the tips in order to get the most uniform emission or the maximum of current? (2) When a tip has a short with the grid, how many tips are affected by the increase of potential in the region near the tip? (3) Is it «better» to have some big meshes with a great number of tips or numerous small ones with a few tips? Is it «better» to have lines of tips or compact arrays of tips distributed on a resistive sheet? (4) What is the «equivalent» resistance of this ensemble? What is its exact meaning?

We report results on the field emitters’ electrical properties uniformity, directly measured by an electrostatic-lens projector apparatus. First, we describe the experimental setup and its resolution capability. Then, we present the emission characteristics of two 1 mm2 microtip arrays measured in ultrahigh vacuum and we compare these characteristics to the results of a numerical approach by taking into account a Gaussian distribution of β (the tip sharpness). From these experimental data, fitted by a numerical description of the probably emitting tips, it is possible to deduce the mean and the standard deviation of tip sharpness in our samples. A comparison between these experiments and microtip atomic force microscopy characterizations coupled to field-emission simulations, shows a good agreement. Finally, we show the effect of hydrogen on the tips’ emissive properties by using the standard Fowler–Nordheim analysis and we explore the induced changes on their statistical emission characteristics. All the...

A microtip field‐emission electron microgun of a few cm3 has been developed for a novel type of semiconductor laser. The electron source is provided by an array of a field emissive microtips cathode each of 1.4 μm base diameter. The source current–voltage characteristic has been determined and its geometrical characteristics have been measured by collecting electrons on a phosphor screen in a region of constant electric field. We have observed that about 100 μA are typically emitted for gate‐cathode voltage (VGC) of 80 V with a half‐aperture angle of 28°. Beam focusing is then realized by two electrostatic lenses: a ‘‘thin hole lens’’ and a quadrupole lens. Using a cathode a 70×500 μm2 rectangular spot on a 10 kV biased anode has been obtained which yields a power density of about 3 kW/cm2. Less than 20% of the total electron beam (current) is lost in the electrostatic optics.

Downsizing and compatibility with MEMS silicon foundries is an attractive path towards a large diffusion of photoacoustic trace gas sensors. As the photoacoustic signal scales inversely with the chamber volume, a trend to miniaturization has been followed by several teams. We review in this article the approach initiated several years ago in our laboratory. Three generations of components, namely a 40 mm3 3D-printed cell, a 3.7 mm3 silicon cell, and a 2.3 mm3 silicon cell with a built-in piezoresistive pressure sensor, have been designed. The models used take into account the viscous and thermal losses, which cannot be neglected for such small-sized resonators. The components have been fabricated either by additive manufacturing or microfabrication and characterized. Based on a compilation of experimental data, a similar sub-ppm limit of detection is demonstrated. All three versions of photoacoustic cells have their own domain of operation as each one has benefits and drawbacks, regarding fabrication, implementation, and ease of use.