Magnetic random access memory with multiple memory layers and improved memory cell selectivity

Abstract

A magnetic random access memory (MRAM) has multiple stacked memory layers, with each memory layer being a plurality of alternating rows of memory cells and electrically conductive access lines. The access lines in each layer are aligned with the access lines in the layers above and below. Similarly the memory cell rows in each layer are aligned with the memory cell rows in the layers above and below, with the memory cells in adjacent layers forming memory cell columns that extending perpendicularly from the MRAM substrate. The memory cells are connected to bit and word lines for addressing selected cells. The MRAM includes electrical circuitry connected to the access lines for directing currents through the access lines in the memory layer of the selected cell and in the access lines directly above or below to generate magnetic fields that switch the magnetic state of the selected cell without switching the magnetic state of non-selected cells in the memory layers above and below.