Planarization method of MRAM device

Abstract

The invention provides a planarization method of an MRAM device. The MRAM device comprises a substrate, and the substrate is provided with a storage unit structure; the storage unit structure at leastcomprises a bottom electrode and a magnetic tunnel junction located on the bottom electrode, and the upper surface of the magnetic tunnel junction is provided with a metal film protection layer. Themethod comprises the following steps: sequentially depositing a polishing barrier layer and a dielectric layer on the substrate; chemically and mechanically polishing the dielectric layer until all the polishing barrier layers above the metal film protective layer are exposed; etching the polishing barrier layer, and removing all the polishing barrier layer on the upper surface of the metal thin film protection layer and part of the polishing barrier layer on the two sides of the metal thin film protection layer. According to the planarization method provided by the invention, the control capability of the polishing end point in the CMP process can be improved, and the electrical interconnection between the MTJ unit and the top electrode in the MRAM device is improved.

Description

technical field [0001] The invention relates to the technical field of magnetic memory, in particular to a method for planarizing an MRAM device. Background technique [0002] Magnetic Random Access Memory (MRAM) is a new type of non-volatile memory. Compared with other types of memory at present, it has fast read and write speeds, can achieve unlimited erasing and writing, and is easy to integrate with current semiconductor processes. In addition, the spin transfer torque (Spin transfer torque, STT) MRAM array using spin current to achieve magnetic moment reversal can realize the miniaturization of the memory cell size. These advantages make MRAM the main development direction of new memory in the future. [0003] The main functional unit in the MRAM device is the MTJ unit, and its structure mainly includes a magnetic free layer / nonmagnetic oxide layer (MgO) / magnetic pinning layer. Driven by an external magnetic field or current, the direction of the magnetic moment of th...

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Problems solved by technology

Due to the different selection ratios of different thin film materials, and there is no mature slurry product for TEOS / SiN / Ta on the market at the same time, therefore, in the actual CMP process, it is necessary to accurately stop the polishing end point above the magnetic tunnel junction The metal thin film protective layer is very challenging, and the surface of the wafer is often uneven, which affects the function of the MRAM device

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