Magnetic random access memory

Abstract

In an MRAM, a current with high current density flows in a line in write operation. When write operation is to be performed with respect to a memory cell existing at the intersection of a write word line and a bit line, a current flows in the write word line from a WWL driver to a voltage down converter. Thereafter, a current flows in the write word line in a direction opposite to the direction of the current flowing in the write operation, i.e., from the voltage down converter to the WWL driver. The same applies to a bit line. For example, after write operation, a current flows in the bit line in a direction opposite to the direction of a current flowing in the write operation.

Description

technical field [0001] The present invention relates to a magnetic random access memory, and more particularly to a method for improving the reliability of a circuit in which a large current flows during writing. Background technique [0002] In recent years, as the phenomenon that the Magnetic Tunnel Junction (MTJ) has a large magnetoresistance ratio (Magneto-Resistive (MR) Ratio) at room temperature has been discovered by researchers, the application of tunneling magnetoresistance effect (Tunneling Magneto- Resistive (TMR)) MRAM realization, began to become a reality. [0003] Even before applying the TMR effect to the MRAM, people have already known the MRAM using the giant magnetoresistance effect (Giant Magneto-Resistive (GMR)). However, the MR ratio of MRAM to which the GMR effect is applied starts from a few percent and is about 10% at most. In addition, in the MRAM using the GMR effect, since a current flows in a low-resistance metal thin film, there is a problem t...

AI Technical Summary

Problems solved by technology

[0027] As described above, in order to prevent the occurrence of electron migration and improve the reliability of the wiring, for example, measures to thicken the wiring have been considered, but this measure is not sufficient for reducing the current density of the wiring. To prevent write errors in unselected cells, the thickness of the wiring must be formed as thin as possible, so that the intensity distribution of the magnetic field generated by the current flowing on the wiring becomes a steep distribution with as narrow a width as possible.

[0028] That is, in the conventional MRAM, it is impossible to realize the increase in storage capacity by miniaturization of the memory cell, the improvement of the reliability of the wiring, and the prevention of writing errors at the same time.

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