Ultrahigh density vertical magnetoresistive random access memory (invited)

In this paper, we present the vertical magnetoresistive random access memor y (VMRAM) design based on micromagnetic simulation analysis. The design uti lizes the vertical giant magnetoresistive effect of the magnetic multilayer . By making the memory element into a ring-shaped magnetic multilayer stack with orthogonal paired word lines, magnetic switching of the memory device becomes very robust. The design also adopts the readback scheme in pseudo spin valve MRAM so that only one transistor is needed for each bit line whi ch can connect hundreds of memory elements, yielding a very high area densi ty. It is estimated that the ultimate area density for the VMRAM is 400 Gbi ts/in.(2). It is suggested that this memory design has the potential to not only replace the present semiconductor memory devices, such as FLASH, but also the potential to replace DRAM, SRAM, and even disk drives. (C) 2000 Am erican Institute of Physics. [S0021-8979(00)66708-7].