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Aims: To develop a new type of microbiological Reference Materials (RMs), displaying long-term stability at room temperature. The purpose was to produce and validate two batches of RMs for the enumeration of Bacillus cereus and Clostridium perfringens. Methods and Results: The RMs were based on spores of B. cereus and Cl. perfringens, adsorbed on calcium carbonate pellets. Two batches of 1000 units were manufactured and validated in compliance with ISO guide 35. After verification of their homogeneity, the stability of the 'RM-B. cereus' and 'RM-Cl. perfringens' batches was proven during at least 36 and 9 months, respectively, at room temperature. The validation study was completed by international collaborative trial involving 12 laboratories, allowing the validation of the assigned values. Conclusions: The methodology developed in this work enabled to produce easy-to-handle and cost-effective RMs, displaying an unprecedented stability at room temperature, a good homogeneity and a precise and validated assigned value. Significance and Impact of the Study: This study revealed new paths for the development of stable microbiological RMs. Overcoming the intrinsic instability of the living cells makes it possible to produce valuable tools for the quality assurance of microbiology laboratories.

Agar contact microbiological sampling techniques, based on a transfer of the microorganisms present on a surface to a culture medium, are widely used to assess and control surface cleanliness and to evaluate microbial contamination levels. The effectiveness of these techniques depends on many environmental parameters that influence the strength of attachment of the bacteria to the surface. In the present study, stainless steel and high density polyethylene surfaces were inoculated with known concentrations of Staphylococcus epidermidis. Following an experimental design, the surfaces were sampled with different types of replicate organism direct agar contact plates and Petrifilm; results indicated that recovery rates were influenced by the presence of egg white albumin or Tween 80 in the inoculum solutions or by the introduction of surfactants into the contact agar of the microbiological sampling techniques. The techniques yielded significantly different results, depending on sampling conditions, underlining the need for a standardization of laboratory experiments to allow relevant comparisons of such techniques.

The main feature of the thermomigration of Al/Si liquid droplets in silicon for the realization of isolation walls in bi-directional power devices is its low thermal budget. Therefore, it is compatible with the utilization of epitaxial substrates for innovative power devices, for example, with reduced on-state resistance. This paper describes the design and realization of a medium power SCR on epitaxy. After structure presentation and voltage blocking capability simulation, the specific issue of thermomigration on (1 1 1)-orientated epitaxial substrates is considered. Limitations to migration are found due to the off-axis cut necessary for good epitaxial growth. Electrical characterization exhibits great agreement with simulation, demonstrating the great potential of thermomigration as a low thermal budget technique for isolation walls processing for both standard structures and new devices on epitaxy.

The copper precursor N,N'-diisopropylacetamidinate has been decomposed at low temperature (80-110°C) in a liquid process under a moderate H2 pressure. Depending on the choice of the solvent, the process leads to a colloidal solution of well controlled copper nanoparticles or the deposition of composite Cu-SiO2 films on the surfaces. The latter layer is highly adhesive to silica surface, behaves as an active seed layer for electroless copper deposition and allows a conformal covering inside deep trenches.

A new method for creating deep junctions extending through the whole thickness of a wafer has recently been demonstrated. Applications are in the field of high power devices. The method uses the thermomigration of melted Al/Si droplets in silicon and allows function electrical isolation. This process requires a specific Rapid Thermal Processing equipment. The purpose of this paper is to discuss the control of the process by end-point detection, that is the optical in situ detection of the emergence of the melted alloy once thermomigration is completed. For this purpose, in situ laser reflectometry and video observation have been used. Experimental results are presented and discussed.

The aim of this study is to develop a new electrical insulating technique available for power devices and specific application devices. The classical process for the fabrication of insulating walls, consists in the diffusion of doping boron atoms from the surface of the wafer. An alternative way to perform this insulating structure is to create deep doping sources located in the region of the future insulating wall, to diffuse these doping atoms until the overlapping of the different diffusion zones and thus to achieve a continuous junction wall. These doping sources are realized by filling small adjacent deep trenches with doped material. This technique was applied on insulating boxes which were made by this way inside an n-type epitaxial layer grown on a p-type substrate. Trenches of 4 micrometers wide have been etched to a depth of approximately 50 micrometers by a high density low pressure helicon plasma reactor at an average rate of 5 micrometers /min. Process is based on an SF6/O2 mix as feed gas and a cryogenic chuck. Then these trenches are filled with in-situ boron doped polycrystalline silicon deposited by low pressure chemical vapor deposition technique using a gaseous mix of silane and diborane. The structures are then annealed in order to create a continuous wall between the adjacent filled trenches. These insulated boxes were electrically tested. The first results showed that it is possible to get a breakdown voltage higher than 200 Volts. This technique is thus promising.

We present a facile, room temperature and “fully liquid” method to specifically produce either copper nanoparticles or thin conductive copper films on silicon substrates by using a dedicated reduction process of mesitylcopper by H2 or an aminoborane.