Static information storage and retrieval – Systems using particular element – Magnetoresistive
Reexamination Certificate
2001-12-21
2003-02-25
Tran, Andrew Q. (Department: 2824)
Static information storage and retrieval
Systems using particular element
Magnetoresistive
C365S171000, C365S173000, C438S003000
Reexamination Certificate
active
06525957
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to electronics, in general, and to electronic components and methods of manufacture, in particular.
BACKGROUND OF THE INVENTION
The density of a magnetic memory component can be increased by reducing the lateral dimension of each magnetic memory cell in the magnetic memory component. As the lateral dimension is reduced, the volume of the magnetic memory cell decreases. Eventually, the volume of the magnetic memory cell will be decreased to the point where the energy barrier for switching the memory state of the magnetic memory cell will be comparable to the thermal energy. At this point of volume reduction, data stored within the magnetic memory cell will be lost.
One technique for alleviating this problem involves keeping the volume of the magnetic memory cell constant by increasing the thickness of the magnetic layer of the magnetic memory cell in which the data is stored. There is an upper physical limit, however, to the thickness of this magnetic layer, due to a trade-off between the magnetic exchange interaction between spins within the magnetic layer and the dipolar interaction between spins within the magnetic layer. The magnetic exchange interaction causes electron spins to align parallel to each other. The dipolar interaction causes spins in different regions of the magnetic layer to be anti-aligned. Below a critical thickness, the exchange interaction is dominant and the memory cell has all spins substantially aligned which is a single magnetic domain. If the thickness of the magnetic layer is increased above its critical thickness, then the dipolar interaction becomes dominant and the magnetic energy of the magnetic layer will be reduced by the formation of undesirable magnetic domains so that regions of the memory cell have spins aligned in substantially different directions. One specific domain structure that forms are magnetic vortices, which are circular domains with no net moment. The removal of these undesirable magnetic vortices requires a magnetic field with a high magnitude, which is incompatible with operating a magnetic memory component.
Accordingly, a need exists for a magnetic memory component with magnetic memory cells having volumes that are increased to, or at least kept above, that necessary for non-volatile data retention while increasing the density of the magnetic memory cells.
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patent: 5659499 (1997-08-01), Chen et al.
patent: 6211090 (2001-04-01), Durlam et al.
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patent: WO 00/58970 (2000-10-01), None
Engel Bradlfy N.
Goronkin Herbert
Rizzo Nicholas D.
Koch William E.
Motorola Inc.
Tran Andrew Q.
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