  The output signal of classical symmetrical Hall plates is an odd function of
the magnetic field component acting perpendicular to the plate. At weak
magnetic field the Hall plate output is linearly proportional to the
perpendicular magnetic field. Magnetic field components parallel to the plate
may also contribute to the output signal via the planar Hall effect. It leads
to even order terms of the in-plane magnetic field in the output signal. At
moderate magnetic field the planar Hall effect adds to the output signal a term
proportional to the square of the in-plane magnetic field. This paper reports
on linear terms of the in-plane magnetic field component to the output signal
of Hall-plates, when they are subjected to mechanical shear stress. The effect
is small for Hall plates but large for Vertical Hall devices in (100)-silicon.
It is fully described by piezo-resistance and piezo-Hall tensors. We present
results of numerical simulations and measurements. Thin devices are less
affected than thick devices. If magnetic angle sensors are made of Vertical
Hall devices, in-plane shear stress leads to a small orthogonality error which
- in contrast to the planar Hall effect - cannot be cancelled out by spinning
current schemes. We propose a compensation circuit to eliminate this
shear-stress induced orthogonality error.
