STT-MRAM cell structures

#1. Field of Invention

#The invention relates generally to magnetic random access memory, and more particularly, to Spin Torque Transfer Magnetic Random Access Memory (STT-MRAM).

#2. Description of Related Art

#Certain embodiments are described in the following detailed description and in reference to the drawings in which:

#FIG. 1 depicts a block diagram of a processor-based system in accordance with an embodiment of the present technique;

#FIG. 2 depicts a schematic diagram of a portion of a memory array having memory cells fabricated in accordance with embodiments of the present invention;

#As previously discussed, a spin torque transfer magnetic random access memory (STT-MRAM) cell is programmed by switching the magnetization of the free layer in the cell's magnetic cell stack. Switching occurs when the current density passing through the memory cell is larger than the critical switching current density. Thus, to program the cell, the programming current density need only be slightly higher than the critical switching current density. Since passing a larger programming current increases the energy consumption and the thermal profile in the cell stack, which affects the integrity and reliability of the cell, it is desirable to decrease the critical switching current without affecting the cell's thermal stability. Applying a lower programming current while maintaining a programming current density that is above the critical switching current density would allow a smaller current to switch the free layer of the cell. The following discussion describes the systems and devices, and the operation of such systems and devices in accordance with the embodiments of the present technique.

#FIG. 1 depicts a processor-based system, generally designated by reference numeral 10. As is explained below, the system 10 may include various electronic devices manufactured in accordance with embodiments of the present technique. The system 10 may be any of a variety of types such as a computer, pager, cellular phone, personal organizer, control circuit, etc. In a typical processor-based system, one or more processors 12, such as a microprocessor, control the processing of system functions and requests in the system 10. As is explained below, the processor 12 and other subcomponents of the system 10 may include resistive memory devices manufactured in accordance with embodiments of the present technique.

#The system 10 typically includes a power supply 14. For instance, if the system 10 is a portable system, the power supply 14 may advantageously include a fuel cell, a power scavenging device, permanent batteries, replaceable batteries, and/or rechargeable batteries. The power supply 14 may also include an AC adapter, so the system 10 may be plugged into a wall outlet, for instance. The power supply 14 may also include a DC adapter such that the system 10 may be plugged into a vehicle cigarette lighter, for instance.