Patent attributes
A MRAM structure is disclosed that includes a metal contact bridge (MCB) which provides an electrical connection between a MTJ top electrode and an overlying bit line. The MCB has a width greater than a MTJ top electrode and serves as an etch stop during bit line etching to prevent sub-trenches from forming adjacent to the top electrode and causing shorts. MCBs also prevent insufficient etching that causes open circuits. A MCB is preferably a metal, metal compound, or alloy such as Ta with low resistivity and high conductivity. The MCB layer is patterned prior to using a dual damascene process to form a bit line contacting each MCB and a bit line pad connection to a word line pad. MCB thickness is thin enough to allow a strong bit line magnetic field for switching a free layer and large enough to function as an efficient oxide etch stop.
