Showing papers by "Joachim Schulz published in 2009"

Comparison of measurement methods for microsystem components: application to microstructures made by the deep x-ray lithography process (x-ray LIGA)

Abstract: The LIGA (a German acronym for lithography, electroplating and molding) process using highly parallel x-rays permits the production of a microstructure with still unique characteristics: high aspect ratio, high accuracy, high perpendicularity and lower roughness of the side wall. From a marketing point of view, this qualitative description might suffice to attract users to the technology. Regarding widespread commercialization and standardization of x-ray LIGA products, our goal is to establish a rigorous dimensional metrology for which we need to understand and quantify uncertainty, which is the key to accuracy. We report on our metrological study using a coordinate measurement machine (CMM) equipped with a fibre probe (3D measurements) which will be compared to two versions of lateral top-view measurements (2D/surface measurements): an optical microscope provided with a micrometric table and a CMM with an image processing sensor; these two types of measurement methods being complementary. In fact, microsystem technology requires measurements to be performed with precision and accuracy within the range of 0.1 µm. In this paper, we present an analysis and a discussion of both types of measurement systems. The precision and reproducibility of the CMM (with fibre probe) during a two-year study will be exposed; a calibrated series part is being measured every time the machine is used. In this case, the CMM is used as a comparator. Its accuracy and the calibration of the ball diameter using an etalon (ceramic gage block) will be exposed. Furthermore, by taking into account the results obtained by the measurement system analysis (MSA), we will show the measurement's impact on the process by taking as an example the fabrication of mm gold gears for watch industry; a quantitative description of process reproducibility and of the influence of processing parameters influence will be possible in the future.

Short-pulse laser induced transient structure formation and ablation studied with time-resolved coherent XUV-scattering

Abstract: The structural dynamics of short-pulse laser irradiated surfaces and nano-structures has been studied with nm spatial and ultrafast temporal resolution by means of single-shot coherent XUV-scattering techniques. The experiments allowed us to time-resolve the formation of laser-induced periodic surface structures, and to follow the expansion and disintegration of nano-objects during laser ablation.

Metrology study of high precision mm parts made by the deep x-ray lithography (LIGA) technique

Abstract: Microcomponents are increasingly applied in industrial products, e.g. smallest gears, springs or the watch industry. Apart from their small dimensions, such components are characterized by a high contour accuracy. Industry requires the tolerances to be in the µm range. Measurement of lateral dimensions in the mm range with submicrometer accuracy and precision, however, results in high requirements on measurement technology. The relevance of this problem is illustrated by the fact that the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) has launched the Collaborative Research Center 1159 on 'New Strategies of Measurement and Inspection for the Production of Microsystems and Nanostructures'. The Institut fur Mikrostrukturtechnik, Karlsruhe (Institute of Microstructure Technology, Karlsruhe), produces microstructures by means of the LIG(A) technique (German acronym for lithography, electrodeposition, molding). Presently, a coordinate measurement machine equipped with an optical fiber probe to measure these microstructures is being tested. This paper will particularly focus on the precision and accuracy of the machine. The rules of measurement system analysis will be applied for this purpose. Following the elimination of the systematic error, reproducibility of deep-etch x-ray lithography will be highlighted using the LIGA production of gold gears as an example.

Electron-correlation-induced interchange of lifetime broadenings of 5s -1 multiplet states in atomic Cs

Abstract: The lifetime broadenings of the most intense 5s photolines of Cs were studied. The aim of this study was to understand the origin of the remarkable differences in the lifetime widths of different 5s{sup -1} multiplet states. The 5s photoelectron spectra of the 6s{yields}6p{sub 1/2,3/2} laser-excited states are presented in the binding energy region of 30-34 eV showing the main 5s photolines of the ground state and laser-excited states as well as the 5s5p{sup 6}6p shakeup satellites. The lifetime widths of the states were determined. The Hartree-Fock calculations were carried out to predict the 5s photoelectron spectrum. The lifetime broadenings of the 5s photolines were found to be due to the transition rates of the subsequent Coster-Kronig transitions to the 5s{sup 2}5p{sup 5} states. It was found that a straightforward single-configuration explanation cannot be given for the lifetime differences. Instead, electron correlation plays an essential role and the lifetime broadenings were found to be predicted well only when configuration interaction between the 5s{sup -1} and 5p{sup -2}5d configurations is taking into account.