Calculation of the dynamic characteristics of micro-mirror element based on thermal micro-actuators

Paper presents a structure of a micro-mirror element driven by thermal micro-actuators. Micro-mirror dimensions are 100x100 um and it was manufactured by a surface micromachining using microelectronics technologies. Thermal microactuator is a bimorph structure consisting of aluminum and silicon dioxide layers with a polysilicon heater between them. The description of manufacturing process for micro-mirror element is given. The micro-mirror motion is achieved by passing an electric current through the heater. The actuator structure is heated and rotates the mirror. The processes of heating and cooling of thermal micro-actuator structure directly affects the characteristics of manufactured micro-mirror, thus the studying of these processes is essential. The report proposes a method for calculating the heating and cooling time, taking into account the influence of the structure geometry, electrical characteristics of external influence and the environment conditions. Also a method for the experimental determination of the dynamic characteristics is proposed, along with the method of electro-thermal analogy. The results of calculation are in good agreement with the experimental data, which allows one to use it to determine the dynamic characteristics of micro-devices based on thermal microactuators.