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Porous-Si-micromachining technique was used for the formation of single-crystalline force-sensor elements, capable of resolving the three vector components of the loading force. Similar structures presented so far are created from deposited polycrystalline Si resistors embedded in multilayered SiO2/Si3N4 membranes, using surface micromachining technique for a cavity formation. In this paper, the authors implanted four piezoresistors in an n-type-perforated membrane, having their reference pairs on the substrate in order to form four half bridges for the transduction of the mechanical stress. They successfully combined the HF-based porous-Si process with conventional doping and Al metallization, thereby offering the possibility of integration with readout and amplifying electronics. The 300times300 mum2 membrane size allows for the formation of large tactile arrays using single-crystalline-sensing elements of superior mechanical properties. They used the finite-element method for modeling the stress distribution in the sensor, and verified the results with real measurements. Finally, they covered the sensors with different elastic silicon-rubber layers, and measured the sensor's altered properties. They used continuum mechanics to describe the behavior of the rubber layer

The paper deals with the analytical estimation of bandwidth and device sensitivity of cantilever- and bridge-type monolithic piezoresistive and capacitive accelerometers using different beam models and of their design sensitivity due to the change of geometrical parameters. Using a simplified two-beams model, closed-form formulae have been derived to give the relationship between the rates of length, width and thickness of the beams and the lowest eigenfrequency characterizing the bandwidth as well as the physical sensitivity of the accelerometers. By means of symbolic derivation, a structural design sensitivity analysis has been carried out to obtain information for the optimal selection of the geometrical parameters.

The deformation of Si/SiN x based square membrane structures are measured by Makyoh topography. The results are compared to finite-element modelling of the structure, and the thermal expansion coefficient of SiN x is extracted.