Thin film magnetic memory device having a highly integrated memory array
View Patent ↗Read word lines and write word lines are provided corresponding to the respective MTJ (Magnetic Tunnel Junction) memory cell rows, and bit lines and reference voltage lines are provided corresponding to the respective MTJ memory cell columns. Adjacent MTJ memory cells share at least one of these signal lines. As a result, the pitches of signal lines provided in the entire memory array can be widened. Thus, the MTJ memory cells can be efficiently arranged, achieving improved integration of the memory array.
1. A thin film magnetic memory device, comprising:
a memory array having a plurality of magnetic memory cells arranged in rows and columns, each of said plurality of magnetic memory cells including
a magnetic storage portion having a resistance value that varies according to a level of storage data to be written by first and second data write currents, and
a memory cell selection gate for passing a data read current therethrough into said magnetic storage portion in a data read operation;
a plurality of read word lines provided corresponding to the respective rows of the magnetic memory cells, for actuating the corresponding memory cell selection gate according to a row selection result in said data read operation;
a plurality of signal lines provided corresponding to the respective columns of the magnetic memory cells, a corresponding one of said plurality of signal lines being shared by adjacent magnetic memory cells in the row direction;
a read/write control circuit for supplying said first data write current and said data read current to said signal lines in a data write operation and said data read operation, respectively;
a plurality of write word lines provided corresponding to the respective rows, and selectively activated according to a row selection result in said data write operation so as to cause said second data write current to flow therethrough; and
a plurality of control switches provided respectively corresponding to said plurality of signal lines, for electrically coupling a reference voltage that is used in said data read operation to a corresponding one of said plurality of signal lines, wherein
said plurality of control switches each couples a selected one of two signal lines corresponding to the respective magnetic memory cells to said reference voltage, according to said column selection result.
2. The thin film magnetic memory device according to claim 1 , wherein adjacent magnetic memory cells in the column direction share a corresponding one of at least one of said plurality of read word lines and said plurality of write word lines.
3. The thin film magnetic memory device according to claim 1 , wherein
said adjacent magnetic memory cells share one of the corresponding write word line and the corresponding signal line, which is located farther from the respective magnetic storage portions, and
said one of the write word line and the signal line has a larger cross-sectional area than that of the other of the write word line and the data line.
4. The thin film magnetic memory device according to claim 1 , wherein one of each write word line and each signal line, which is located farther from the corresponding magnetic storage portions, is formed from a material having higher electromigration resistance than that of the other of each write word line and each signal line.