Metal Films for MEMS Pressure Sensors: Comparison of Al, Ti, Al-Ti Alloy and Al/Ti Film Stacks

Thermo-mechanical stability of metal structures is one of the key factors affecting accuracy of micro-electromechanical (MEMS) piezoresistive pressure sensors. In this work, we present the measurement results of stress and hysteresis for the following metals deposited in the same sputtering equipment -Al, Ti, Al-Ti alloy and stacks of Al/Ti films-enabling, for the first time, a direct comparison between their thermo-mechanical properties supported with analysis of surface morphology (grain size, hillocks and voids).