Active shielding for a circuit comprising magnetically sensitive materials
View Patent ↗Magnetic shielding is provided using a variety of methods, systems, devices and circuits. Aspects of present invention provide a method for providing magnetic shielding for a circuit comprising magnetically sensitive materials. The circuit is actively shielded from a disturbing magnetic field. A corresponding semiconductor device is also provided. The method and device can provide shielding for strong disturbing magnetic fields.
1. A method for providing magnetic shielding for an integrated circuit die having magnetically sensitive materials that use a magneto-resistive effect to store data, the magneto-resistive effect controlled using a local magnetic field, the method comprising:
sensing a disturbing magnetic field near the magnetically sensitive material; and
responsive to the sensing, actively shielding the magnetically sensitive materials from the disturbing magnetic field by generating a compensating magnetic field;
wherein, measuring a disturbing magnetic field includes determining a direction of the disturbing magnetic field, and the compensating magnetic field is in a primarily opposite direction from the disturbing magnetic field; and
wherein compensating for the measured disturbing magnetic field includes generating a spin-polarized current through the circuit.
2. A semiconductor device comprising:
a storage circuit comprising magnetically sensitive materials that use a magneto-resistive effect to store data, the magneto-resistive effect controlled using a local magnetic field;
a sensor for measuring the disturbing magnetic field; and a protective layer for actively shielding the magnetically sensitive materials from a disturbing magnetic field in response to measuring the disturbing magnetic field,
wherein the protective layer for actively shielding the circuit includes:
a compensation generator for generating a magnetic field in the protective layer for compensating for the disturbing magnetic field; and
wherein the compensation generator comprises a magnetic field source for generating a magnetic compensation field for compensating for the disturbing magnetic field.
3. The semiconductor device according to claim 2 , wherein the magnetic field source is a planar coil.
4. The semiconductor device according to claim 2 , wherein the magnetic field source is a current carrying conductor.
5. The semiconductor device according to claim 2 , wherein the magnetic field source is integrated in the storage circuit.
6. The semiconductor device according to claim 2 , wherein the compensation generator includes a decision circuit for determining whether active feedback is needed.
7. The semiconductor device according to claim 6 , wherein the decision circuit includes a comparator for comparing the measured disturbing magnetic field with a pre-set threshold value.
8. The semiconductor device according claim 2 , the storage circuit being an MRAM device including MRAM elements, wherein the sensor is an MRAM element.
9. The semiconductor device according to claim 8 , wherein the MRAM element used for the sensor has a same stack composition as the MRAM elements in the storage circuit.
10. The semiconductor device according to claim 8 , wherein the MRAM element used for the sensor is more sensitive to magnetic fields than the MRAM elements used in the storage circuit.
11. The semiconductor device according to claim 8 , wherein the write lines of the MRAM device are used for the magnetic field source.
12. The semiconductor device according to claim 2 , further including passive magnetic shielding.