Is Switzerland Still a Lucrative Place for Manufacturers of Drug Substances to Produce Their Products?

Pharmaceutical manufacturers are coming under increasing pricing pressure as a result of healthcare reforms and are therefore looking to low wage countries in the Far East. Often, the outcome is a process that is not fully mature in economic terms. Contract synthesis manufacturers, such as Siegfried, offer assistance here with its comprehensive pharmaceutical know-how in order to establish efficient and low-cost processes at an early stage. Siegfried's strengths lie in its many years experience in the pharmaceutical industry and in the network of contacts it has built up over the years with technical and material suppliers. Therefore, as far as Switzerland as a location for manufacturing is concerned, Siegfried looks to the future with confidence

Laser cleaning of silicon wafers : mechanisms and efficiencies

Laser Cleaning (SLC) process. Using a frequency doubled, Q-switched Nd:YAG laser (FWHM=8 ns) we removed polystyrene (PS) particles with diameters from 110-2000 nm from industrial silicon wafers by the DLC process. The experiments have been carried out both in ambient conditions as well as in high vacuum (10-6 mbar) and the cleaned areas have been characterized by atomic force microscopy for damage inspection. Besides the determining the cleaning thresholds in laser fluence for a large interval of particle size we could show that particle removal in DLC is due to a combination of at least three effects: thermal substrate expansion, local substrate ablation due to field enhancement at the particle and explosive evaporation of adsorbed humidity from the air. Which effect dominates the process is subject to the boundary conditions. For our laser parameters no damage free DLC was possible, i.e. whenever a particle was removed by DLC we damaged the substrate by local field enhancement. In our SLC experiments we determined the amount of superheating of a liquid layer adjacent to surfaces with controlled roughness that is necessary for bubble nucleation. On smooth surfaces high superheatins were necessary, in good agreement with theoretical predictions. Rough surfaces exhibited only a much smaller superheating

Laser assisted particle removal from Silicon wafers

We have studied the removal of submicrometer particles from silicon wafers by the steam laser cleaning (SLC) and dry laser cleaning (DLC) processes. These processes are currently being investigated as new promising cleaning technologies for complementing traditional methods in industrial applications. For SLC a thin liquid layer (e.g. a water-alcohol mixture) is condensed onto the substrate, and is subsequently evaporated by irradiating the surface with a short laser pulse. The DLC process, on the other hand, relies only on the laser pulse, without application of a vapor jet. Using well-characterized monodisperse polystyrene and silica particles as well as irregularly shaped alumina particles with diameters down to 60nm we have systematically investigated the efficiency of the two processes. The influence of laser pulse duration from the nanosecond to the femtosecond range was studied. For the DLC we were able to measure the acceleration of the silicon surface due to thermal expansion for DLC. Our results demonstrate that for the gentle cleaning of silicon wafers the SLC is a very efficient method and for particles smaller in diameter than 400nm it is superior to DLC. This is due to lower cleaning thresholds in laser fluence for SLC compared to DLC for the removal of small particles. DLC may cause serious surface damage by field enhancement under the contaminants, an effect that hasonly rarely been taken into account in laser cleaning studies so far and is also discussed here

Optical near field effects in surface nanostructuring and laser cleaning

We present a method for directly imaging the undisturbed near field of a particle resting on a surface. A comparison with numerical computations shows good agreement with the results of our experiments. These results have important consequences for laser-assisted particle removal where field enhancement may cause local surface damage and is one of the physical key processes in this cleaning method. On the other hand, the application of near fields at particles allows structuring of surfaces with structure dimensions in the order of 100 nm and even below

Laser-induced Particle Removal from Silicon Wafers

The cleaning of silicon surfaces from submicron dust particles has been studied by means of the Steam Laser Cleaning (SLC) process and compared to Dry Laser Cleaning (DLC) which is used nowadays in many applications. For SLC a thin liquid layer (e.g. a water-alcohol mixture) is condensed onto the substrate, and is subsequently evaporated by irradiating the surface with a short laser pulse. The DLC process, on the other hand, only relies on the laser pulse, without application of a vapor jet. We have systematically investigated the efficiency of these two processes for the removal of well-characterized polymer, silica and alumina particles of various sizes down to 60 nm in diameter, and have also studied the influence of light wavelength and laser pulse duration for nanosecond and picosecond pulses. The results demonstrate that for the gentle cleaning of silicon wafers SLC is a very efficient method and is superior to DLC. An effect which so far has only rarely been taken into account for laser cleaning is the field enhancement under the particles, which can give rise to serious surface damage, in particular when cleaning pulses in the picosecond and femtosecond range in the DLC are applied