| Popis: |
The main body of this thesis focuses on the fabrication of micro-electro-mechanical (MEM) fluidic flow sensor for integration with large scale integration (LSI) neuron circuit and robot. The proposed MEM sensor consists of a) piezoresistive wheatstone bridge circuits consisting of p-type boron doped regions in n-type single crystalline silicon, integrated with patterned metallization, b) silicon cantilever beams that are integrated with the aforementioned piezoresistive wheatstone bridge/metallization circuits, c) out of plane flaps that are integrated at the free end of the silicon cantilever beams. The p-type piezoresistive wheatstone bridge microfeatures are fabricated by boron implantation in n-type single crystalline silicon, forming p-n junction. Patterned metallizations have been integrated with boron doped microfeatures and the circuits have been characterised by electrical probing. The electrical circuits and microcantilever beams have been fabricated on the device layer of silicon on insulator (SOI) wafers, followed by release of the microstructures by bulk micromachining step, where the silicon handle wafer and buried silicon oxide of the SOI wafer beneath the pre-defined cantilever beams has been removed. However, devices fabricated in the first design iteration did not meet the specifications and therefore could not be integrated with the LSI neuron circuit. In an attempt to address this issue, the MEM device has been redesigned to meet the specifications. For the fabrication of out of plane flaps, the plastic deformation magnetic assembly (PDMA) method has been developed. The final part of this thesis focuses on amorphous silicon carbide thin films and investigation of their suitability for application in SiC membrane based pressure sensors. As amorphous SiC films have been found to not be robust, circular membranes of thermally grown polycrystalline 3C-SiC films for application in absolute pressure sensing devices have been fabricated. Boron doped polycrystalline silicon strain gauges in half active wheatstone bridge arrangement have been integrated with SiC released membranes to transduce pressure induced mechanical deformation of the membranes into electrical signal. |
