HALLSENSOR, EINGEBAUT IN EINER CMOS INTEGRIERTEN SCHALTUNG

A Hall-effect sensor HS' incorporated in a CMOS integrated circuit IC' is formed with a well 2' as the sensor active layer in a substrate 1'. Heavily doped regions 31' to 34' in the well 2' are connected to respective sensor metal contacts 41' to 44'. The upper surface S' of the substrate 1' is covered by a field oxide layer 5' having a thickness between 0.8 mu m and 1.0 mu m. Over the field oxide layer 5' in a region 50' surrounding the sensor contacts 41' to 44', a polysilicon blocking layer 6' is provided to block the disturbing influence of ions migrating in the field oxide layer 5'. In another embodiment, the blocking layer is formed under the field oxide layer.