KR20020057762A - TMR device and the fabricating method thereof - Google Patents

Abstract

PURPOSE: A tunnel ring magneto-resistance element and a method for fabricating the same are provided to fabricate efficiently an oxide tunneling barrier by improving a lowering phenomenon of a magneto-resistive ratio. CONSTITUTION: An anti-ferromagnetic layer(110) is deposited on a silicon substrate. A fixing layer(120) is deposited on the anti-ferromagnetic layer(110). An oxide tunneling barrier(130) is deposited on the fixing layer(120). A free layer(140) is deposited on the oxide tunneling barrier(130). An FeN layer(150) is formed between the fixing layer(120) and the oxide later tunnel barrier(130). The fixing layer(120) is formed by ferromagnetic material such as CoFe or NiFe. The FeN layer(150) is formed by implanting nitrogen gas into the fixing layer(120) and combining Fe ions with N ions on a surface of the fixing layer(120).

Description

Tunneling magnetoresistive element and manufacturing method thereof

The present invention relates to a tunneling magnetoresistive device and a method of manufacturing the same, and more particularly, to tunneling in which a nitride film is formed to prevent a decrease in the MR ratio that may occur during the manufacturing of the oxide tunneling barrier of the tunneling magnetoresistive device. A magnetoresistive element and a method of manufacturing the same.

Tunneling magnetoresistive (TMR) elements, which are the basic elements of conventional magnetic random access memory (MRAM) cells, are shown with an antiferromagnetic layer (AFM) 10 as shown in the schematic structure of FIG. A ferromagnetic (FM) 20 formed of CoFe, NiFe, or the like, a ferromagnetic material in which magnetization is fixed by an exchange bias coupling, and freely in response to a magnetic field from a medium (signal field) in which magnetization is not fixed. A free layer 40 which is a rotating ferromagnetic material and an oxide tunneling barrier 30 which is an insulating layer separating the fixed layer 20 and the free layer 40 are formed.

The operation of the TMR element will be described with reference to the schematic diagram of FIG. 2. In FIG. 2A, when the magnetization spins of the pinned layer and the free layer are in opposite directions, when a current is applied, a small current flows through the tunnel barrier due to the high magnetoresistance of the TMR element. On the contrary, in FIG. 2B, since the direction of spin of the pinned layer 20 and the free layer 40 is the same, the magnetoresistance is low, and a large amount of current flows when a current is applied. In this case, the magnetoresistive ratio (MR ratio) is expressed by the following equation.

In this case, a high MR ratio makes it easier to determine the direction of spin of the pinned layer 20 and the free layer 40, thereby making it possible to make an excellent MRAM for reading and writing information of " 1 " and " 0 ".

However, in the conventional TMR device, when the oxide tunnel barrier 30 is formed, an aluminum thin film of about 10 mW is usually coated on the fixed layer 20, and then an insulator of alumina (Al ₂ O ₃ ) is formed by plasma oxidation. When the oxidation is insufficient (Fig. 3 (a)), a portion of the aluminum metal (Al) of the lower layer remains, the tunneling current is reduced, and if the oxidation is excessively progressed (Fig. 3 (b)), the surface of the fixed layer 20 The surface oxide layer 50 is oxidized to form spin fluctuations, and the spin reaction of the free layer 40 is reduced, thereby reducing the MR ratio.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a method of manufacturing a tunneling magnetoresistive element for efficiently manufacturing an oxide tunnel barrier.

Another object of the present invention is to provide a tunneling magnetoresistive element manufactured by the above manufacturing method.

1 is a schematic cross-sectional view of a conventional tunneling magnetoresistive element;

2 is a schematic diagram of an operation of a tunneling magnetoresistive element;

3A is a schematic cross-sectional view of a TMR element when plasma oxidation is insufficient, and (b) is a schematic cross-sectional view of a TMR element when plasma oxidation is excessive.

4 is a schematic diagram of a manufacturing process of a tunneling magnetoresistive element according to the present invention;

5 is a schematic cross-sectional view of a tunneling magnetoresistive element according to the present invention.

Explanation of symbols on the main parts of the drawings

10,110: antiferromagnetic layer 20,120: fixed layer

30,130: tunnel barrier 40,140: free layer

50: oxide layer 150: FeN layer

In order to achieve the above object, in the method of manufacturing a tunneling magnetoresistive element in which an antiferromagnetic layer, a pinned layer, an oxide tunnel barrier and a free layer are sequentially stacked on a silicon substrate,

The method may further include a nitriding step of forming a FeN layer by treating nitrogen gas on the fixed layer, and the forming of the oxide tunnel barrier may include forming an aluminum thin film on the FeN layer and forming an oxide tunnel tunnel by plasma oxidation. Step included. In addition, after the nitriding step, it is preferable to further include the step of heating the substrate.

In the tunneling magnetoresistive element in which an antiferromagnetic layer, a pinned layer, an oxide tunnel barrier, and a free layer are sequentially stacked on a silicon substrate in order to achieve the above another object,

The FeN layer by nitrogen gas treatment was included between the fixed layer and the oxide tunnel tunnel barrier.

Hereinafter, with reference to the accompanying drawings will be described in detail an embodiment according to the tunneling magnetoresistive element and the method of manufacturing the present invention.

4 is a schematic manufacturing process diagram of a tunneling magnetoresistive element according to the present invention.

According to Figure 4, the method of manufacturing a TMR device of the present invention comprises the steps of preparing a substrate to form a TMR device; Forming a buffer layer on the substrate; Forming an antiferromagnetic layer on the buffer layer; Forming a pinned layer of ferromagnetic material on the antiferromagnetic layer; Treating the fixed layer with nitrogen gas to form a FeN layer; Forming an aluminum thin film on the FeN layer; Oxidizing the aluminum thin film with plasma to form an oxide tunnel barrier as an insulating layer; And forming a free layer of ferromagnetic material on the oxide tunnel barrier.

The manufacturing process will be described in detail through examples.

First, a silicon wafer substrate having a thermal oxide of about 2000 GPa was deposited in a vacuum chamber, and a tantalum buffer layer was coated with about 300 GPa by a sputtering method, and then about 200 GPa of IrMn serving as pinning of the TMR element. (Antiferromagnetic layer) and CoFe (fixed layer) of about 50 GPa is formed. Then, the surface is treated at 200 ° C. in an N ₂ atmosphere to form a FeN layer on top of CoFe. Subsequently, an aluminum metal of about 10 mW is coated and a very thin alumina (Al ₂ O ₃ ) tunnel barrier is formed by plasma oxidation. At this time, the thin FeN layer on the fixed layer prevents the phenomenon of CoFe (fixed layer) is oxidized. A 200 nm NiFe (free layer) is formed on the tunnel barrier to complete the TMR element. In addition, after forming the FeN layer, annealing (annealing) in the range of 200 ~ 300 ℃ to reduce the crystal defect (lattice defect) and strain (strain) at the interface to obtain a stronger spin polarization (spin polarization).

5 is a schematic cross-sectional view of a tunneling magnetoresistive element according to the present invention.

Referring to FIG. 5, the antiferromagnetic layer 110, the pinned layer 120, the oxide tunnel barrier 130, and the free layer 140 are sequentially stacked, and between the pinned layer 120 and the oxide tunnel barrier 130. The FeN layer 150, which is a soft magnetic material by nitrogen gas treatment, is formed.

The pinned layer 120 is made of a ferromagnetic material such as CoFe or NiFe, the FeN layer 150 is formed by combining the unstable Fe ions and N ions on the surface of the pinned layer by flowing nitrogen gas to the pinned layer 120.

In the TMR device, when the power is applied, the MR ratio is increased by differentiating high or low magnetoresistance according to the directions of magnetic spins of the pinned layer 20 and the free layer 40 which are two ferromagnetic materials.

As described above, the TMR device according to the present invention can be effectively used for MRAM fabrication because the fixed layer is protected from lack or excessive plasma oxidation during oxide tunnel barrier formation.

Although the present invention has been described with reference to the embodiments with reference to the drawings, this is merely exemplary, it will be understood by those skilled in the art that various modifications and equivalent embodiments are possible. Therefore, the true technical protection scope of the present invention will be defined only by the appended claims.

Claims (3)

In the method of manufacturing a tunneling magnetoresistive element in which an antiferromagnetic layer, a pinned layer, an oxide tunnel barrier and a free layer are sequentially stacked on a silicon substrate, Further comprising a nitriding step of forming a FeN layer by treating nitrogen gas on the fixed layer, The forming of the oxide tunnel barrier may include forming an aluminum thin film on the FeN layer and forming an oxide tunnel tunnel by plasma oxidation. The method of claim 1, Subsequent to the nitriding step, further comprising the step of heating the substrate. In a tunneling magnetoresistive element in which an antiferromagnetic layer, a pinned layer, an oxide tunnel barrier, and a free layer are sequentially stacked on a silicon substrate, Tunneling magnetoresistance device, characterized in that the FeN layer by nitrogen gas treatment between the fixed layer and the oxide tunnel tunnel barrier.