FINITE-ELEMENT ANALYSIS OF THERMAL-STRESSES IN A SILICON PRESSURE SENSOR FOR VARIOUS DIE-MOUNT MATERIALS

The performance of a silicon micromachined pressure sensor can be sign ificantly affected by the die-attach material and the mounting configu ration of the die in its package. Packaging stresses transmitted to th e piezoresistive element implanted in the sensing die can induce an er ror in the voltage output of the sensor. A finite-element model is dev eloped to analyse the effects of different die-mounting configurations , die-attach materials and sensor-element constraints. The model calcu lates the temperature-induced stress affecting the piezoresistive elem ent ion-implanted on the surface of the pressure-sensing die. Aluminiu m nitride produces the minimum offset. The 110 mil glass constraint pr ovides better mechanical isolation from the stresses produced by the t hermal mismatch between the silicon/glass component and the substrate.