Piezo-hall effect in CMOS-based vertical hall devices

This paper reports on the piezo-Hall effect in CMOS-based five-contact vertical Hall sensors (VHS) able to measure in-plane magnetic field components. The geometry of such devices and the characteristic current flow in the deep n-wells strongly differ from those of structures used so far to characterize the piezo-Hall response. In contrast to standard planar Hall plates, homogeneous mechanical in-plane stress was found to cause a weak change in the magnetic sensitivity of the VHS. The paper presents the custom-made measurement setup and its detailed characterization as well as experimental results acquired using single VHS and coupled sensor systems comprising four VHS connected in parallel. The experimental results are supported by finite element simulations. It is concluded, that the low sensitivity change is due to the vertical current density changes induced by the applied mechanical stress.