Design and Calibration of Optimized (111) Silicon Stress Sensing Test Chips

The (111) surface of silicon offers unique advantages for fabrication of piezoresistive stress sensors. Resistive sensor elements fabricated on this particular surface respond to all six components comprising the state of stress. Hence, a multi-element rosette has the capability of measuring the complete stress state at a point in the material. Four of the stress component measurements are temperature compensated. This is in contrast to standard sensors fabricated on traditional (100) silicon, where only four stress components can be measured (two in a temperature compensated manner). Several generations of (111) silicon test chips have been designed, fabricated, and calibrated to demonstrate the capabilities of these advanced sensors