Calibration and optimization of interconnect based MEMS test structures for predicting thermo-mechanical stress in metallization

We have shown that the in-plane stress in aluminium metallisation can be observed using a rotating beam sensor structure. This shows that the extrinsic stress from the mismatch in expansion coefficient between the aluminium and the silicon substrate dominates over the compressive stress from the sputter growth. Sintering the layers at temperatures above 150/spl deg/C reduces this compressive stress due to the action of creep. Calibration of the rotation of the device has been undertaken by direct comparison to high resolution x-ray diffraction measurements and these show that the sensor has a resolution better than 2.8MPa.