Patent ID: 8058696
Filing Date: 2011-11-15
Classification: B82Y,G11C,H01L

Abstract:
1. A magnetic memory element comprising: a stack of at least two magnetic tunneling junctions (MTJs), each of the at least two MTJs of the stack separated from another of the at least two MTJs of the same stack by a non-magnetic layer, the non-magnetic layer being amorphous, each of the at least two MTJs of the stack having a unique resistance associated therewith, the stack capable of storing more than one bit of information, each of the at least two MTJs including a barrier layer having a thickness associated therewith, each of the at least two MTJs further including a free layer and a fixed layer, the barrier layer of a first one of the at least two MTJs directly contacting and formed on top of the fixed layer of the first one of the at least two MTJs and the free layer of the first one of the at least two MTJs directly contacting and formed on top of the barrier layer of the of the first one of the at least two MTJs, the non-magnetic layer directly contacting and formed on top of the free layer of the first one of the at least two MTJs, the free layer of a second one of the at least two MTJs directly contacting and formed on top of the non-magnetic layer and the barrier layer of the second one of the at least two MTJs formed on top of the free layer of the second one of the at least two MTJs and the fixed layer of the second one of the at least two MTJs directly contacting and formed on top of the barrier layer of the second one of the at least two MTJs, the barrier layer of each of the at least two MTJs of the stack having a thickness that is different from the thickness of the barrier layers of all of the other MTJs of the stack, the thickness of the barrier layer of each of the at least two MTJs of the stack being at least in part indicative of the resistance of each of the MTJs of the stack, the non-magnetic layer being made of a material selected from a group comprising: Nickel niobium(NiNb), Nickel phosphorous(NiP), Nickel vanadium(NiV), Nickel bororn(NiB) and copper-zirconium(CuZr), the stack being capable of storing one bit in each of the MTJs of the stack wherein when current is applied to the magnetic memory element, the multiple bits stored in the stack define the state of the stack and are based on the level of the current applied to the magnetic memory element so that when current is changed from one level to another, the state of the stack is switched accordingly.