STT-MRAM MTJ manufacturing method with in-situ annealing

摘要

A spin transfer torque magnetic random access memory (STTMRAM) element and a method of manufacturing the same is disclosed having a free sub-layer structure with enhanced internal stiffness. A first free sub-layer is deposited, the first free sub-layer being made partially of boron (B), annealing is performed of the STTMRAM element at a first temperature after depositing the first free sub-layer to reduce the B content at an interface between the first free sub-layer and the barrier layer, the annealing causing a second free sub-layer to be formed on top of the first free sub-layer and being made partially of B, the amount of B of the second free sub-layer being greater than the amount of B in the first free sub-layer. Cooling down the STTMRAM element to a second temperature that is lower than the first temperature and depositing a third free sub-layer directly on top of the second free layer, with the third free sub-layer being made partially of boron (B), wherein the amount of B in the third sub-free layer is less than the amount of B in the second free sub-layer.

主权项

1. A method of manufacturing a spin transfer torque magnetic random access memory (STTMRAM) magnetic tunnel junction film stack comprising:
a) first depositing a magnetic interface layer on top of a barrier layer to form a magnetic tunnel junction (MTJ), the magnetic interface layer being made partially of boron (B) b) after the first depositing step, annealing the STTMRAM MTJ film stack at a first temperature after depositing the magnetic interface layer, the annealing being in-situ within a deposition system without breaking the vacuum thereby avoiding oxidization and contamination of the surface of the magnetic interface layer; c) after the annealing step, cooling down the STTMRAM MTJ film stack to a second temperature that is lower than the first temperature; and d) after the cooling down step, second depositing a top layer on top of the magnetic interface layer, wherein the top layer is made of a single layer or has a multi-layer structure necessary to make the MTJ stack function in the STTMRAM MTJ film stack, wherein the top layer comprises at least one magnetic sub-layer.