Method for preparing magnetic random access memory conductive hard mask

Abstract

The invention provides a method for preparing a magnetic random access memory conductive hard mask, comprising the steps of: (1) providing a surface-polished CMOS substrate having a metal through hole, and depositing a bottom electrode, a magnetic tunnel junction multilayer film, the etching stop layer of a conductive hard mask layer, a conductive hard mask, and the mask layer of the conductive hard mask on the substrate; (2) patterning a conductive hard mask pattern, and transferring the pattern to the top of the mask layer of the conductive hard mask; (3) partially etching the conductive hard mask and removing the residues; and (4) continuing etching the remaining conductive hard mask, stopping the etching on the etching stop layer and maintaining partial over-etching. Since the conductive hard mask is etched and post-processed in two steps during the etching process, the excessively low etching selection ratio during the etching process, and the potential influence on the performance of the magnetic tunnel junction caused by the introduction of Cl are solved, thereby contributing to the improvement in the magnetic property, the electrical property and the yield of the magnetic random access memory.

Description

technical field [0001] The invention relates to a method for preparing a conductive hard mask (C-HM, Conductive Hard Mask) of a magnetic random access memory (MRAM), belonging to the technical field of magnetic random access memory (MRAM, Magnetic Radom Access Memory). Background technique [0002] In recent years, MRAM using Magnetic Tunnel Junction (MTJ) is considered to be the future solid-state non-volatile memory, which has the characteristics of high-speed reading and writing, large capacity and low energy consumption. Ferromagnetic MTJ is usually a sandwich structure, which includes: a magnetic memory layer, which can change the magnetization direction to record different data; an insulating tunnel barrier layer in the middle; a magnetic reference layer, located on the other side of the tunnel barrier layer, Its magnetization direction does not change. [0003] In order to record information in this magnetoresistive element, it is suggested to use a writing method ba...

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Problems solved by technology

[0008] In order to solve the above-mentioned technical problems, the present invention provides a method for preparing the conductive hard mask of magnetic random access memory, select Cl 2 etc. as the main gas to etch the conductive hard mask, and keep the etching depth at 80% to 95% of the thickness of the entire conductive hard mask, which not only forms a good hard mask shape, but also solves the problem of C / F In the base gas, the etching selectivity ratio is too low; then, high temperature H 2 O vapor for Cl removal

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