Thin film magnetic memory device including memory cells having a magnetic tunnel junction

1. A thin film magnetic memory device, comprising:

a plurality of memory cells for storing data, wherein

each memory cell includes

a magnetic storage portion having an electric resistance value varying according to storage data, and

a read access element for allowing a data read current to be selectively supplied to said magnetic storage portion corresponding to a memory cell selected for a read operation,

said magnetic storage portion includes

a first magnetic layer having a fixed magnetization direction,

second and third magnetic layers that are magnetized in opposite directions according to an applied data write magnetic field,

a non-magnetic, conductive intermediate layer formed between said second and third magnetic layers, and

an insulating layer formed between one of said second and third magnetic layers and said first magnetic layer, and

in data write operation, at least part of said data write magnetic field is generated by a first data write current flowing through said intermediate layer.

2. The thin film magnetic memory device according to claim 1 , wherein said intermediate layer is shared by at least two of said plurality of memory cells.

3. The thin film magnetic memory device according to claim 2 , wherein

said plurality of memory cells are arranged in a matrix, and

said intermediate layer has a strip-shaped planar shape so as to correspond to one of a memory cell row and a memory cell column.

4. The thin film magnetic memory device according to claim 1 , wherein

said plurality of memory cells are arranged in a matrix,

said thin film magnetic memory device further comprising:

a plurality of first data write lines respectively corresponding to one of memory cell rows and memory cell columns, for passing said first data write current therethrough, each of said plurality of first data write lines being formed using said intermediate layer; and

a plurality of second data write lines respectively corresponding to the other of said memory cell rows and said memory cell columns, for passing therethrough a second data write current for generating said data write magnetic field in said data write operation, wherein

respective magnetization directions of said second and third magnetic layers are rewritable in a memory cell having said first and second data write currents being respectively supplied to corresponding first and second data write lines.

5. The thin film magnetic memory device according to claim 4 , wherein

each said magnetic storage portions are formed in a layer located above said read access element, and

each said data write line are formed in a layer located above said magnetic storage portion.

6. The thin film magnetic memory device according to claim 1 , wherein

in said data read operation, said access element electrically couples said magnetic storage portion to a fixed voltage, and

said data read current is supplied to said magnetic storage portion through said intermediate layer.

7. The thin film magnetic memory device according to claim 1 , further comprising:

a read data line for passing said data read current therethrough in data read operation, wherein

said access element electrically couples said magnetic storage portion to said read data line in said data read operation, and

said intermediate layer is set to a fixed voltage in said data read operation.

8. The thin film magnetic memory device according to claim 1 , wherein

said plurality of memory cells are arranged in a matrix, and

said intermediate layer extends in a memory cell column direction as a plurality of data lines corresponding to the respective memory cell columns,

said thin film magnetic memory device further comprising:

a data write circuit for setting one end of one of a pair of data lines to a first voltage and one end of the other data line to a second voltage according to a write data level in data write operation; and

a current switch provided for every pair of data lines, for electrically coupling the other ends of a corresponding pair of data lines to each other in said data write operation.

9. The thin film magnetic memory device according to claim 1 , wherein each said memory cell further includes a write access element for allowing said first data write current to be selectively supplied to said intermediate layer corresponding to a memory cell selected for said data write operation.

10. The thin film magnetic memory device according to claim 9 , wherein

said plurality of memory cells are arranged in a matrix,

said thin film magnetic memory device further comprising:

first and second data lines provided for every memory cell column, wherein

in said data write operation, one of said first and second data lines that correspond to a memory cell column including a selected memory cell is set to one of first and second voltages and the other of said first and second data line is set to the other of said first and second voltages according to a write data level, and

each said write access element is connected in series with said intermediate layer between corresponding first and second data lines, and turned ON in a memory cell row including said selected memory cell.

11. The thin film magnetic memory device according to claim 10 , wherein said read access element includes a transistor for electrically connecting the magnetic storage portion of a memory cell selected for data read operation between a prescribed voltage and one of corresponding first and second data lines that receives said data read current.

12. The thin film magnetic memory device according to claim 10 , further comprising:

a read word line provided for every memory cell row, and set to a voltage higher than a prescribed voltage in a memory cell row including a memory cell selected for data read operation, wherein

in said data read operation, said intermediate layer is coupled to said prescribed voltage through one of said first and second data lines, and

said read access element has a diode element electrically coupled between a corresponding read word line and said magnetic storage portion and having a forward direction from said corresponding read word line toward said magnetic storage portion.

13. A thin film magnetic memory device, comprising:

a plurality of memory cells for storing data, wherein

each said memory cell includes

a magnetic storage portion having an electric resistance value varying according to storage data, and

an access transistor for allowing a data read current to be selectively supplied to said magnetic storage portion corresponding to a memory cell selected for a data read operation, and

said magnetic storage portion includes

a first magnetic layer having a fixed magnetization direction,

second and third magnetic layers that are magnetized in opposite directions according to an applied data write magnetic field and have different magnetic moments,

a non-magnetic intermediate layer formed between said second and third magnetic layers, and

an insulating layer formed between one of said second and third magnetic layers and said first magnetic layer,

said thin film magnetic memory device further comprising:

a data write line for passing therethrough a data write current for generating said data write magnetic field in data write operation, wherein said intermediate layer is formed as a planar layer so as to be shared by at least two of said plurality of memory cells.

14. The thin film magnetic memory device according to claim 13 , wherein said intermediate layer is formed of a conductive material and fixed to a prescribed voltage.