Very deep trenches (up to 200 pm) with high aspect ratios (up to 10) in silicon and polymers are etched using a fluorine-based plasma (SFd02/CHF3). Isotropic, positively and negatively (i.e. reverse) tapered as well as.fully vertical walls with smooth suriaces are achieved by controlling the plasma chemistry. A convenient way to find the processing conditions needed for a vertical wall is described the black silicon method. This new procedure is checked for three different reactive ion etchers (RIE), two parallel-plate reactors and a hexode. The influence of the RF power, pressure and gas mixture on the profile will be shown. Scanning electron microscope (SEM) photos are included to demonstrate the black silicon method, the influence of the gases on the profile, and the use of this method in fabricating microelectromechanical systems (MEMS).

This paper discusses the modeling, design and realization of micromachined Coriolis mass flow sensors. A lumped element model is used to analyze and predict the sensor performance. The model is used to design a sensor for a flow range of 0-1.2 g h −1 with a maximum pressure drop of 1 bar. The sensor was realized using semi-circular channels just beneath the surface of a silicon wafer. The channels have thin silicon nitride walls to minimize the channel mass with respect to the mass of the moving fluid. Special comb-shaped electrodes are integrated on the channels for capacitive readout of the extremely small Coriolis displacements. The comb-shaped electrode design eliminates the need for multiple metal layers and sacrificial layer etching methods. Furthermore, it prevents squeezed film damping due to a thin layer of air between the capacitor electrodes. As a result, the sensor operates at atmospheric pressure with a quality factor in the order of 40 and does not require vacuum packaging like other micro Coriolis flow sensors. Measurement results using water, ethanol, white gas and argon are presented, showing that the sensor measures true mass flow. The measurement error is currently in the order of 1% of the full scale of 1.2 g h −1 .

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This article presents nano-slit electrospray emitters fabricated by a micro-to nanofluidic via technology. The main advantage of the technology is the ability to position freely suspended nanochannels anywhere on a microfluidic chip, where leak-tight delivery of fluid from a fluid reservoir can be established through long microchannels. The technology has proven to be useful in creating electrospray emitters coupled to freely suspended microchannels. It was observed that filling of nanochannels through via connections with integrated microchannels occurs not only due to bulk capillary action. These observations lead to a redesign of the electrospray chips. Repeatable electrospray IV-curves could be obtained from fabricated nano-slit electrospray emitters. Moreover, integration of on-chip microfluidic components is one of the possibilities of the fluidic via technology presented.