Monolithically integrated GMR angle sensors for automotive applications with extended magnetic stability

Abstract:
A monolithically integrated GMR angle sensor for automotive applications is presented. The vertical integration concept allows a combination of our spin-valve type GMR angle sensors with conventional CMOS or bipolar base technologies providing the signal conditioning. The PtMn based sensor stack exhibits an excellent thermal stability. A combination of temperature and magnetic field, however, leads to a drift of the magnetization direction of the reference system and therefore, to an increased angular error. A reduction of the net magnetic moment as well as the film thickness of the pinned and reference layer of the artificial antiferromagnet leads to a significant improvement of the robustness against thermo-magnetic stress. As a result, an overall angular error of <1deg over lifetime at magnetic inductions up to 90mT and 150deg C is obtained.