A High Sensitive Piezoresistive Sensor for Stress Measurements in Packaged Semiconductor Die

The authors have developed new two-dimensional piezoresistive stress sensors that replace conventional serpentine resistor rosettes. These sensors are named van der Pauw (VDP) sensors as they are based upon four-terminal van der Pauw type resistance measurements. The resistance of such a sensor is size independent, and hence can be made as small as lithographically possible to capture stresses in critical areas on the surface of a packaged semiconductor die. It was predicted theoretically that the VDP sensor should exhibit a greater than three times improvement in sensitivity relative to resistor sensor rosettes. Then the response of actual VDP structures fabricated on (111) silicon surface was characterized under uniaxial load using four-point-bending tests. These experimental results confirm that the VDP stress sensitivities are more than three times higher than those of their corresponding resistor sensor counterpart