Using 3D Hall Sensors to Measure Mechanical Stress for Planar Sensor's Sensitivity Compensation

A new method to measure and compensate for changes in mechanical in-plane stress in CMOS-integrated 3D Hall sensors is presented. Changes in stress induce a significant degradation of the planar Hall sensor's sensitivity. Encapsulated sensors in industry-typical plastic packages are especially affected by environmental variations (e.g., temperature, humidity, etc.), leading to a loss in angular resolution and reduced repeatability. A complete second-order model is determined considering in-plane stress between 0 MPa and 150 MPa, temperatures of -35-65°C, and 3D magnetic fields up to 22 mT. Package-related stress changes are obtained with the model so that the planar Hall sensor's sensitivity gets quantized and compensated. The sensitivity error is reduced to an average value below 0.35% for 24 samples without additional stress sensors.