Etching method of magnetic tunnel junction double-layer conductive hard mask

Abstract

The invention provides an etching method of a magnetic tunnel junction double-layer conductive hard mask. The method comprises the following steps of S1, supplying a substrate which comprises a magnetic tunnel junction multi-layer film; S2, successively forming a tantalum film layer and a titanium nitride film layer; S3, performing patterned transferring of a magnetic tunnel junction pattern to the titanium nitride film layer, and finishing patterned definition of the pattern by means of photoresist and an organic anti-reflection layer; S4, performing dry etching on the titanium nitride film layer by means of Cl2 / CH4 mixed gas, thereby transferring the pattern to the tantalum film layer; S5, performing selective etching on the titanium nitride film layer and the tantalum film layer by means of HCl / He / O2, thereby finishing patterning of a double-layer conductive hard mask; and S6, eliminating the superfluous photoresist and the superfluous organic anti-reflection layer by means of an oxygen ashing process. The etching method effective prevents problems such as size increase of the magnetic tunnel junction pattern in double-layer mask transferring and advanced excessive consumption of the tantalum film layer. Furthermore the etching method reduces a shortcircuit risk of an MRAM circuit bit line and an MTJ unit.

Description

technical field [0001] The invention relates to a magnetic tunnel junction (MTJ, Magnetic Tunnel Junction) hard mask, in particular to an etching method for a magnetic tunnel junction conductive double-layer hard mask, and belongs 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. consumption characteristics. 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 The direction of magnetization remains u...

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Problems solved by technology

[0007] The invention provides a magnetic tunnel junction (MTJ) double-layer conductive hard mask and an etching method thereof, which is particularly suitable for preparing MRAM circuits of 65nm and below, in order to solve the problem of Ta on SiN (or SiO 2 ) selection ratio is too low; the MTJ pattern changes in size when the double-layer mask is transferred; SiN (or SiO 2 ) film is thinner, the Ta film layer is excessively consumed in advance; in CH 3 Preparation of MTJ units under OH / Ar dry etching conditions, SiN (or SiO 2 ) film is thicker, as the sacrificial layer of SiN (or SiO 2 ) The selection ratio of MTJ is not high; it reduces the risk of MRAM circuit bit line and MTJ cell short circuit

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