C. Khan Malek

Experimental and theoretical performances of an etched lamellar multilayer grating in the 1 keV region

Abstract The performance of a lamellar multilayer amplitude grating with a 0.24 μm pitch produced using holography and reactive ion etching is assessed in the 1 keV region with synchrotron radiation. The position and efficiency of the various orders of grating diffraction are compared to values calculated within the framework of kinematical or dynamical models. The unique properties of these optical devices are discussed.

Reactive ion etching of multilayer mirrors for X-ray projection lithography masks

Abstract Reflection masks for use in X-ray projection lithography can be obtained by etching synthetic multilayer interference mirrors. Reactive ion etching of such mirrors was investigated with respect to the etch rate and etch profile. Patterned Mo/C, W/C, Mo/Si, and W/Si multilayer mirrors were reactive ion etched in a fluorinated (SF 6 /CHF 3 ) gas mixture. Ni/C and Cr/C multilayer mirrors could be etched in a chlorinated gas (Cl 2 /Ar). The etching speed varied from 0.02 nm/s to 3 nm/s depending on the material and the process parameters. The groove depth could be controlled within one layer by following the reflectivity of the multilayer mirror with an helium-neon laser during the transfer process. Multilayer mirror features in the 0.1 μm range could be produced.

Performance of Etched Laminar Multilayer Gratings in the Soft X-ray Region

Mo/C laminar multilayer amplitude gratings for use in the 1 keV or 250 eV region were fabricated by holography or electron beam lithography followed by reactive ion etching. The gratings were tested with monochromatized synchrotron radiation and their performance was compared to theoretical values.

X-ray lithography at the Super-ACO storage ring of Orsay (France)

Abstract The implementation of an X-ray lithography facility using the synchrotron radiation delivered by Super-ACO is described and results concerning our X-ray mask technology are reported.An extensive study of two low-temperature SiC deposition methods (sputtering and PECVD) has allowed the optimization of a strong amorphous membrane technology. These membranes are 45×45 mm 2 large with a tensile stress of about +100 MPa. The in-absorber stress minimization for gold electroplating or tungsten RF sputtering has been combined with thick single resist pattern transfer methods to manufacture masks with critical dimensions as low as 100 nm.

Tests of 250‐nm pitch multilayer gratings in the XUV low‐energy range on the Super‐ACO Storage Ring at LURE

Two laminar amplitude multilayer gratings with 250‐nm pitch were produced using UV holography and reactive ion etching. The diffraction properties of these structures were measured at 150 eV using synchrotron radiation. The experimental results, giving the position and absolute reflectivity of the various orders, are discussed within a kinematical model.

Modeling and Simulation of the Flow of a Thermoplastic Polymer during Filling of a Cylindrical Micro‐Cavity

This work is related to experiments and modelling concerning viscous polymer flow such as cyclo‐olefin polymer (COP) and cyco‐olefin copolymer (COC) arising in the hot embossing process in order to understand and predict the filling of microcavities. The simulation results are obtained for axisymmetric geometries. The filling time and the dimensions of polymer with the rheological and experimental process parameters are obtained. From the variations of the radius characterizing the squeeze flow of the polymers between plates with or without cavities, it is possible to relate the rheological properties (fluidity index, consistency, melt flow index and viscosity) to the aptitude of the polymers to reproduce the geometrical shape and surface asperities of a microstructured mould. The flow imposed to the polymeric material in shear or elongational mode was correlated to the rheological approach. This approach allows to better understand the compression of thermoplastic disks as well as the filling mechanism o...

Modelling and experimental determination of the replication of a cylindrical shape relief

In that paper, one uses the concepts of contact mechanics to describe the quality of reproduction of cylindrical cavity shape by hot embossing. It results in a negative replica of the initial shape. This model takes into account the deformation of the polymer material imposed by the forming process. These results point out the influence of experimental parameters (temperature, pressure) as well as those of the elastic modulus (Young’s modulus and Poisson’s ratio). The analytical data are compared with the metrology results obtained using a scanning mechanical microscope in two or three‐dimensional mode. The set of data enables a predictive approach of the engraving quality depending on the polymer mechanical properties. The final goal is to adapt this model to the hot embossing process.

On the use of hot embossing for the reproduction of the surface topography of mould microreliefs

Abstract This article describes the quality of reproduction of microcavities structured into mould substrates which were filled by the imposed flow of amorphous polymeric materials. The rheology of the selected materials (cyclic olefin copolymer, COC) depends on the experimental parameters (temperature, pressure) used for the hot embossing process. To support the experimental data, the polymers were qualified by their melt flow index, flow index and consistency. The efficiency of the filling procedure into microcavities with smaller and smaller size is described using the potentialities of a customized Scanning Mechanical Microscope (SMM).

Microfluidics on foil

Abstract The concept of microfluidics on foil opens up new opportunities for combining the advantages of having a flexible substrate with reel to reel processing which have the potential to be the basis for extremely cheap micro products. To reach this goal foil substrates must be combined with micro manufacturing technologies well adapted to these substrates. Some technologies are already available, some are subject of current research and some still have to be conceived. Here, technologies like reel to reel embossing, reel to reel laminating and laser ablation/cutting as well as laser welding will be discussed. A polymer electronics based alcohol sensor is presented and aspects of combining polymer (opto-)electronics and microfluidics on one foil based substrate will be discussed.

Fabrication of Multilayer Mirror Zone Plates and Gratings for Use with Soft X-Rays

Multilayer mirror gratings and Fresnel zone plates were produced using a multistep process utilizing microfabrication techniques. The gratings were generated by holography and the zone plates by electron beam lithography on Mo/C multilayer mirrors. The pattern transfer was performed by reactive ion etching in a fluorinated plasma after an intermediate lift-off step. Gratings with pitches down to 0.24 µm as well as linear, circular (with 0.3 µm outer zone), and elliptical Fresnel zone plates (with 0.8µm outer zones) were produced.