A novel U-shaped magnetic shield for perpendicular MRAM

We have developed a U-shaped magnetic shield for packaging perpendicular magnetoresistive random access memories (MRAMs) and have determined that a non-oriented silicon steel is best suited for this shield in terms of fabrication and magnetic properties. Use of this shield material suppressed magnetic flux saturation for an external magnetic field of up to 300[Oe], which exceeds the target of 250[Oe]. A magnetic source can thus be placed as close as 1 cm to a shielded MRAM. An MRAM chip is packaged by separating the shield into two parts and then mounting the lower part, the chip, and the upper part in sequence. If the gap between the parts is 20[μm] and the permeability of the gap is 30, the target performance is still achieved. This shield is thus promising for high-speed, low-power MRAMs.