Single-chip bridge-type magnetic field sensor and preparation method thereof

A method to make a single-chip full-bridge magnetic field sensor, comprising the steps of:

• interconnecting one or more GMR or MTJ magnetoresistive sensing elements electrically interconnected in series to produce a sensor arm, wherein the full-bridge sensor comprises four sensor arms respectively;
• Interconnecting the four sensor arms are electrically to form a Wheatstone bridge;
• and
• patterning the GMR or MTJ magnetoresistive sensing element into a shape that has a magnetic easy axis, wherein the magnetization direction of a free layer points into the direction of said easy axis of said patterned GMR or MTJ magnetoresistive sensing element.

A single-chip half-bridge magnetic field sensor, comprising

• two magnetoresistive sensor arms, each of which includes one or more GMR or MTJ magnetoresistive sensing elements;
• each GMR or MTJ magnetoresistive sensing element is configured as a spin-valve comprising a free layer and a pinned layer;
• the magnetization direction of the pinned layer of each GMR or MTJ magnetoresistive sensing element is set in the same direction;
• an angle for the magnetization direction of the free layer of each GMR or MTJ magnetoresistive sensing element, such that in the absence of an applied magnetic field, all free layers have the same absolute value of the magnetization angle;
• and
• the polarities of the magnetization directions of the free layers of the adjacent magnetoresistive sensor arms have are different with respect to the pinned layer magnetization direction.