A surface micromachined polysilicon membrane, compatible with IC technology, was technologically designed and mechanically and thermally simulated by 3D finite element 'COSMOS' program in order to investigate its capability to work as micro hot plates for gas sensing applications. The optimized lay-out of hot plate consists of a polysilicon membrane of area of 110 by 110 micrometers 2 supported by four 'poly' suspended bridges and a central 'poly' pillar (MWCP). The air gap between membrane and substrate is equal to 1 micrometers . Within this paper, the simulation results are shown as a function of input power and surface area of the membrane. At room temperature the following results were obtained. The maximum normal stress has a value of 151.12 N/m2 and is situated at a distance of 20 micrometers around the central pillar. Also, the maximum displacement has a value of 3.81 by 10-4 micrometers and it is located at about half distance between the center of the membrane and its lateral edge. At an input power of 100 mW applied to the MWCP structure, the strain-stress spatial distributions have been qualitatively preserved with respect to RT situation but all the values increased by about 1300 times. The value of this normal stress for the MWCP structure is now about 196.45728 by 103 N/m2. For an input power of 100 mW, the maximum displacements of the membrane are located in the same place as in the RT case, and their values are lower than 0.1 micrometers .
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