摘要:
The present invention is directed to a method for reading and writing an STT-MRAM multi-level cell (MLC), which includes a plurality of memory elements coupled in series. The method detects the resistance states of individual memory elements in an MLC by sequentially writing at least one of the plurality of memory element to the low resistance state in order of ascending write current threshold. If a written element switches the resistance state thereof after the write step, then the written element was in the high resistance state prior to the write step. Otherwise, the written element was in the low resistance state prior to the write step. The switching of the resistance state can be ascertained by comparing the resistance or voltage values of the plurality of memory elements before and after writing each of the plurality of memory elements in accordance with the embodiments of the present invention.
摘要:
The present invention is directed to a spin transfer torque (STT) MRAM device having a perpendicular magnetic tunnel junction (MTJ) memory element. The memory element includes a perpendicular MTJ structure in between a non-magnetic seed layer and a non-magnetic cap layer. The MTJ structure comprises a magnetic free layer structure and a magnetic reference layer structure with an insulating tunnel junction layer interposed therebetween, an anti-ferromagnetic coupling layer formed adjacent to the magnetic reference layer structure, and a magnetic fixed layer formed adjacent to the anti-ferromagnetic coupling layer. At least one of the magnetic free and reference layer structures includes a non-magnetic perpendicular enhancement layer, which improves the perpendicular anisotropy of magnetic layers adjacent thereto.
摘要:
The present invention is directed to a semiconductor memory device including a plurality of first level contacts arranged in an array with every third row vacant along a first direction, thereby forming multiple contact regions separated by multiple vacant regions along the first direction with each of the multiple contact regions including a first row and a second row of the first level contacts extending along a second direction; a first and second plurality of second level contacts formed on top of the first level contacts with the second plurality of second level contacts having elongated shape extending into the vacant regions adjacent thereto; and a first and second plurality of memory elements formed on top of the first and second plurality of second level contacts, respectively, thereby permitting the memory elements to have greater center-to-center distance between two closest neighbors than the first level contacts.
摘要:
The present invention is directed to a spin transfer torque (STT) MRAM device having a perpendicular magnetic tunnel junction (MTJ) memory element. The memory element includes a perpendicular MTJ structure in between a non-magnetic seed layer and a non-magnetic cap layer. The MTJ structure comprises a magnetic free layer structure and a magnetic reference layer structure with an insulating tunnel junction layer interposed therebetween, an anti-ferromagnetic coupling layer formed adjacent to the magnetic reference layer structure, and a magnetic fixed layer formed adjacent to the anti-ferromagnetic coupling layer. At least one of the magnetic free and reference layer structures includes a non-magnetic perpendicular enhancement layer, which improves the perpendicular anisotropy of magnetic layers adjacent thereto.
摘要:
The present invention is directed to a method for reading and writing an STT-MRAM multi-level cell (MLC), which includes a plurality of MTJ memory elements coupled in series. The method detects the resistance states of individual MTJ memory elements in an MLC by sequentially writing each memory element to the low resistance state in order of ascending parallelizing write current threshold. If a written element switches the resistance state thereof after the write step, then the written element was in the high resistance state prior to the write step. Otherwise, the written element was in the low resistance state prior to the write step. The switching of the resistance state can be ascertained by comparing the resistance or voltage values of the plurality of memory elements before and after writing each of the plurality of memory elements in accordance with the embodiments of the present invention.