A method for preparing a magnetic tunnel junction using tantalum oxide as a hard mask

Abstract

The invention provides a method for preparing a magnetic tunnel junction using tantalum oxide as a hard mask, the steps are as follows: S1: providing a substrate including an MTJ film layer; S2: sequentially forming a tantalum film layer and a tantalum oxide film on the substrate layer; S3: pattern transfer MTJ pattern to the tantalum oxide film layer; S4: etch the tantalum oxide film layer to transfer the pattern to the tantalum film layer; S5: selectively etch the tantalum oxide film layer and the tantalum film layer to make The MTJ pattern is transferred to the MTJ film layer; S6: Use ashing process to remove residual organic matter; S7: Use tantalum oxide as a hard mask to etch the MTJ film layer; S8: Use CVD to grow a layer of SiN to protect the etched surface. MTJ edge exposed after etching; S9: SiO grown by CVD method 2 Fill the etched MTJ part; S10: SiO 2 The filled MTJ surface is ground down until Ta on Ta 2 o 5 Grind it all off.

Description

technical field [0001] The present invention relates to a kind of preparation method of magnetic tunnel junction (MTJ, Mag1netic Tunnel Junction), particularly relate to a kind of tantalum oxide (Ta 2 o 5 ) is a method for preparing a magnetic tunnel junction with a hard mask, belonging to the technical field of integrated circuit manufacturing. Background technique [0002] In recent years, Magnetic Random Access Memory (MRAM, Magnetic Radom Access Memory) using the magnetoresistance effect of Magnetic Tunnel Junction (MTJ) is considered to be the future solid-state non-volatile memory, which has high-speed reading and writing, large capacity and low energy consumption. specialty. Ferromagnetic MTJ is usually a sandwich structure, which has 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, which ...

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Problems solved by technology

Therefore, with CF 4 As an etching gas, it is difficult to form a clear and sharp sidewall of the Ta mask, resulting in an ill-defined mask, which affects the patterning of the MTJ; at the same time, because the Ta film is not protected by a dielectric layer, the Ta film The thickness will be further reduced and an oval-shaped membrane cap will be formed, which will increase the risk of short circuit between bit line and MTJ

Before the Ta film layer is etched, in order to prevent the dielectric layer from being completely etched away, the thickness of the dielectric layer can usually be increased. However, when using a thicker dielectric layer, the size of the MTJ pattern will decrease when the dielectric layer is transferred. It will become larger, which is very unfavorable for the miniaturization of MTJ, especially not suitable for the preparation of MRAM circuits of 65nm and below

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