Authors: J. Jakovenko, M. Husak, E. Burian and T. Lalinsky
Affilation: Czech Technical University, Czech Republic
Pages: 332 - 335
Keywords: MEMS, modeling, simulation, technology
In this project we discuss the thermomechanical simulations performed in the aim of optimising the GaAs based Micromechanical Thermal Converter that creates heart of Microwave Transmitted power sensor. Conception of the absorbed power measurement is based on thermal conversion where absorbed RF power is transformed into thermal power inside a thermally isolated system. By means of thermal simulations we propose a GaAs Micromechanical Thermal Converter design and layout of the HFET heater and temperature sensor placed on thermally isolated cantilever beam or bridge. Spatial temperature dependences, thermal time constant and power to temperature dependences at different ambient atmospheres are calculated from the heat distribution. The 3D thermal and thermo-mechanical simulations of the sensor structures were performed using CoventorWare from Microcosm Technologies. Thermo-mechanical numerical modelling and simulation have significant influence on optimal topology design of the thermo converter. The main thermo converter characteristics have been optimised and evaluated. The most important ones are the temperature distribution over the sensing area, thermal time response, sensitivity analysis and evaluation of the mechanical stresses caused by deposition (initial stress) and by temperature changes in thermo converter structure. GaAs multilayer cantilever beam creates optimal conditions for both the monolithic integration of GaAs based Heterostructure Field Effect Transistors (HFETs) and thermal isolation of the microwave sensor elements.