Thermal Hysteresis Analysis of MEMS Pressure Sensors

Thermal hysteresis reduction is usually a difficult task to tackle for micromachined pressure sensors especially when shrinking piezoresistive transducer (PRT) sensing elements. Since thermal hysteresis involves the entire thermal cycling history and complicated material properties that vary with temperatures, viscoplastic deformation makes the problem very complicated when dealing with high-precision sensor signals. The approach to simplify and quickly resolve the thermal hysteresis problem is the key methodology proposed by this paper. It is found the layout and volume of metal pads and runners have significant impact on the thermal hysteresis voltage shift. Strategically, we may move the aluminum bond pads away from the transducer and reduce the bond pad size to lower down the effect from the thermal stress hysteresis of aluminum on a silicon sensing element.