KR20040000886A - MRAM device and methof for manufacturing thereof - Google Patents

Abstract

PURPOSE: A magnetic random access memory(MRAM) device and a fabrication method thereof are provided to solve problems due to alien substances and etching damage of a tunnel insulation film. CONSTITUTION: A word line(51) is arranged on a substrate(50) along one direction. The first ferromagnetic material film(53) is formed on an area of the above word line. The second ferromagnetic material film(57a) is formed on an upper part of the first ferromagnetic material film. A tunnel insulation film(56) is formed on the first ferromagnetic material film to cover a bottom plane and sides of the second ferromagnetic material film. And a bit line(58) is arranged along one direction orthogonal to the above word line by being adjacent to the tunnel insulation film and the second ferromagnetic material film.

Description

Magnetic random access memory (MRRAM) device and manufacturing method thereof {MRAM device and methof for manufacturing technique}

BACKGROUND OF THE INVENTION Field of the Invention The present invention relates to a semiconductor memory device, and more particularly, to a magnetic random access memory (MRAM) device formed from magnetic tunnel junction (MTJ) cells that can be written as magnetic stimulation, and a method of manufacturing the same. It is about.

Recently, a magnetic technology (MRAM: Magnetic Random Access Memories) technology is rapidly emerging as a new technical application of the magnetic material.

This is an attempt to implement a memory device by using a large magnetoresistance (GMR) phenomenon or spin polarization magnetic permeation phenomenon caused by spin having a great effect on electron transfer.

The former is to implement a GMR magnetic memory device using a phenomenon in which the resistance in the case where the spin directions are different in the two magnetic layers between the nonmagnetic layers is significantly different.

The latter is to implement a magnetically transparent junction memory device using the phenomenon that the transmission of current is much better than the case where the same spin direction is different in the two magnetic layers with the insulating layer interposed therebetween.

The success of this MRAM will enable nonvolatile memory that combines the advantages of today's semiconductor SRAM with the speed and density of DRAM.

In addition, the success of MRAM will emerge as a new memory technology with significantly lower power consumption, lower cost, and simpler production process than semiconductor memory devices.

Such a magnetic random access memory (MRAM) has a known memory effect on the electrical resistance of a magnetically variable memory cell.

As shown in FIG. 1, the MRAM includes a word line 1 arranged in a row direction, and a bit line arranged in a column direction so as to be orthogonal to the word line 1 at regular intervals ( 6) and a magnetic tunnel junction junction (MTJ) cell 2 at the intersection of the word line 1 and the bit line 6.

In this case, the magnetic tunnel junction cell 2 is composed of a fixed layer or a first magnetic layer 3, a tunnel barrier layer 4 and a free layer or a second magnetic layer 5.

In the MTJ cell, information storage is performed by changing the magnetization direction of the second magnetic layer 5 opposite to the magnetization direction of the first magnetic layer 3.

The magnetic field required for this is generated by the current at the word line and the current at the bit line.

The magnetic field overlaps in the MTJ cell region, which is the intersection of the word line and the bit line.

When the magnetization directions of the two magnetic layers are set to be the same, the MTJ cell has a low electrical resistance, and conversely, the MTJ cell has a high resistance when the magnetization directions of the two magnetic layers are not the same or antiparallel.

This resistance variation between the parallel and antiparallel magnetization directions in the two magnetic layers is used for information storage in digital memory applications.

There is a need for a reliable MTJ cell for more efficient information storage of a magnetic random access memory (MRMA) device exhibiting such characteristics.

Hereinafter, a magnetic random access memory (MRAM) device and a method of manufacturing the same according to the related art will be described with reference to the accompanying drawings.

2 is a cross-sectional structural view of a magnetic random access memory device including an MTJ cell according to the prior art.

The prior art relates to a magnetic tunnel junction (MTJ) cell formed at the intersection of a word line and a bit line in an MRAM.

In the magnetic random access memory device according to the related art, the first ferromagnetic layer 22, the tunnel insulation layer 23, and the second ferromagnetic layer 24 are stacked on one region of the word line 21 as illustrated in FIG. 2. The bit lines 26 are formed in contact with the second ferromagnetic film 24 and orthogonal to the word lines 21.

In the method of manufacturing a magnetic tunnel junction cell of a conventional magnetic random access memory device having the above configuration, as shown in FIG. 2, the word line WL 21 is formed on the substrate 20 so as to be arranged in one line direction. do.

The first ferromagnetic material, the tunnel insulating film, and the second ferromagnetic material are sequentially deposited on the entire surface of the substrate including the word line 21.

Thereafter, the second ferromagnetic material, the tunnel insulating film, and the first ferromagnetic material are sequentially dry-etched so as to remain in only one region (cell region) of the word line 21.

As a result, an MTJ cell in which the first ferromagnetic film 22, the tunnel insulating film 23, and the second ferromagnetic film 24 are stacked is formed.

Next, after the interlayer insulating layer 25 is deposited on the entire surface of the substrate 20 including the MTJ cell, the planarization process is performed to expose the upper portion of the second ferromagnetic layer 24.

The bit line 26 is formed to be in contact with the second ferromagnetic layer 24 and to be arranged in a direction orthogonal to the word line 21.

If manufactured according to the method described above, the tunnel insulating film having a very thin thickness (about several tens of micrometers) between the first and second ferromagnetic films must be dry-etched together with the first and second ferromagnetic films. This may cause a problem that the tunnel insulating film loses its original insulating properties.

In addition, foreign matter may adhere to the tunnel insulating layer, which may cause a short problem between the first and second ferromagnetic layers.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to provide a magnetic random access memory device and a method of manufacturing the same capable of preventing problems caused by etching damage of a tunnel insulating film and problems caused by foreign matter adhesion. .

The magnetic random access memory device of the present invention for achieving the above object comprises a word line arranged in one direction on a substrate; A first ferromagnetic film formed on one region of the word line; A second ferromagnetic film formed on the first ferromagnetic film; A tunnel insulating film formed on the first ferromagnetic film to surround a lower surface and a side surface of the second ferromagnetic film; And a bit line in contact with the tunnel insulating layer and the second ferromagnetic layer and arranged in a direction orthogonal to the word line.

Sidewall spacers may be further provided on both side surfaces of the first ferromagnetic layer and the tunnel insulating layer.

Further, a first interlayer insulating film is further provided on the substrate on both sides of the word line, and a second interlayer insulating film is further provided on both sides of the first ferromagnetic film and the tunnel insulating film.

A method of manufacturing a magnetic random access memory device of the present invention having the above configuration includes the steps of: forming a word line to be arranged in one direction on a substrate; Stacking a first ferromagnetic layer and a sacrificial layer on one region of the word line; Depositing and planarizing an interlayer insulating film on both sides of the first ferromagnetic film and the sacrificial film; Removing the sacrificial layer to form a groove on the first ferromagnetic layer; Forming a tunnel insulating film in a groove on the first ferromagnetic film, and simultaneously forming a second ferromagnetic film having a lower surface and a side surface covered by the tunnel insulating film; And forming a bit line in contact with the tunnel insulating layer and the second ferromagnetic layer and arranged in a direction orthogonal to the word line.

The tunnel insulating film and the second ferromagnetic film may be formed by sequentially depositing an insulating film and a ferromagnetic material on the interlayer insulating film including grooves on the first ferromagnetic film, and the ferromagnetic material and the ferromagnetic material to expose the upper portion of the interlayer insulating film. Planarizing the insulating film.

In addition, sidewall spacers may be further formed on both side surfaces of the first ferromagnetic layer and the sacrificial layer before forming the interlayer insulating layer.

1 is a schematic diagram of an MTJ cell between a wordline and a bitline

2 is a structural cross-sectional view of a magnetic random access memory device including an MTJ cell according to the prior art;

3 is a structural cross-sectional view of a magnetic random access memory device including an MTJ cell according to a first embodiment of the present invention;

4A through 4E are process cross-sectional views illustrating a method of manufacturing a magnetic random access memory device including an MTJ cell according to a first embodiment of the present invention.

5 is a structural cross-sectional view of a magnetic random access memory device including an MTJ cell according to a second embodiment of the present invention;

6A through 6E are cross-sectional views illustrating a method of manufacturing a magnetic random access memory device including an MTJ cell according to a second embodiment of the present invention.

Explanation of symbols on the main parts of the drawings

50, 60: substrate 51, 61: word line

52, 62: first interlayer insulating film 53, 63: first ferromagnetic film

54, 64 tunnel insulating film 55, 66 second interlayer insulating film

65 side wall spacer 56, 67 tunnel insulating film

57, 68: second ferromagnetic material 57a, 68a: second ferromagnetic film

58, 69: bitline

Hereinafter, a magnetic random access memory device and a method of manufacturing the same according to an exemplary embodiment of the present invention will be described with reference to the accompanying drawings.

The present invention relates to a magnetic tunnel junction cell of a magnetic random access memory device, in order to prevent the tunnel insulation layer from being etched at the surface where the first and second ferromagnetic layers of the magnetic tunnel junction cell meet.

Hereinafter, description will be made for each embodiment.

First embodiment

A magnetic random access memory device and a method of manufacturing the same according to the first embodiment of the present invention will be described with reference to the accompanying drawings.

3 is a structural cross-sectional view of a magnetic random access memory device including an MTJ cell according to a first embodiment of the present invention, and FIGS. 4A to 4E are magnetic random access memory devices including an MTJ cell according to a first embodiment of the present invention. The process cross section which shows the manufacturing method of.

The magnetic random access memory device according to the first embodiment of the present invention has a word line 51 arranged in one direction on the substrate 50 as shown in FIG. 3, and the substrate is exposed so that the top of the word line 51 is exposed. The first interlayer insulating film 52 is formed on both sides of the 50.

In addition, a first ferromagnetic film 53 is formed on one region (cell region) of the word line 51, and a tunnel insulating film 56 and a second ferromagnetic film 57a are formed on the first ferromagnetic film 53. Formed.

In this case, the tunnel insulating layer 56 is formed to surround the lower surface and the side surface of the second ferromagnetic layer 57a.

A second interlayer insulating layer 55 is formed on the entire surface of the substrate 50 except for the upper portions of the tunnel insulating layer 56 and the second ferromagnetic layer 57a.

The bit line 58 is arranged in contact with the upper portion of the tunnel insulating layer 56 and the second ferromagnetic layer 57a and orthogonal to the word line 51.

In the method of manufacturing the magnetic random access memory device according to the first embodiment of the present invention having the above configuration, the word lines 51 are formed on the substrate 50 so as to be arranged in one line direction as shown in FIG. 4A. do.

Thereafter, a first interlayer insulating layer 52 is deposited on the entire surface of the substrate 50 including the word line 51.

The first interlayer insulating film 52 is planarized so that the upper portion of the word line 51 is exposed by a chemical mechanical polishing process.

Next, the first ferromagnetic material and the sacrificial film are sequentially deposited on the first interlayer insulating film 52 including the word line 51, and then the sacrificial film and the first ferromagnetic material are sequentially dry-etched by a photo process, and then the first ferromagnetic material is first etched in the cell region. The ferromagnetic film 53 and the sacrificial film 54 are laminated.

At this time, the first ferromagnetic material is an oxide ferromagnetic material, and the sacrificial film 54 is a material that does not contain oxygen, such as TiN.

Next, as shown in FIG. 4B, a second interlayer insulating film 55 is deposited on the entire surface of the substrate 50 including the first ferromagnetic film 53 and the sacrificial film 54.

The second interlayer insulating film 55 is planarized to expose the sacrificial film 54 by a chemical mechanical polishing process.

As shown in FIG. 4C, only the sacrificial layer 54 is selectively removed by wet etching to form grooves on the first ferromagnetic layer 53 as much as the cell region.

When the sacrificial layer 54 is removed by wet etching as described above, the first ferromagnetic layer 53 is partially oxidized, and thus the TMR (Tunneling Magneto-Resistance) characteristics may be degraded. A part of the surface of the first ferromagnetic film 53 surface-oxidized by a dry etching method is removed.

Subsequently, a tunnel insulating film 56 is deposited in the same chamber as shown in Fig. 4D.

In this case, since the oxide ferromagnetic material is used as the first ferromagnetic film 53, the problem of oxidizing the first ferromagnetic film 53 during the air exposure or the wet process can be prevented.

In this case, the tunnel insulating layer 56 is formed using an Al 2 O 3 material.

Next, a second ferromagnetic material 57 is deposited on the tunnel insulating film 56 including the grooves on the first ferromagnetic film 53.

Subsequently, as shown in FIG. 4E, the second ferromagnetic material 57 and the tunnel insulating layer 56 are etched back to expose the second interlayer insulating layer 55 to divide the magnetic tunnel junction cell into cell units. And planarization by a chemical mechanical polishing (CMP) process to form the tunnel insulating film 56 and the second ferromagnetic film 57a in the grooves above the first ferromagnetic film 53.

In this case, the tunnel insulating layer 56 surrounds the lower surface and the side surface of the second ferromagnetic layer 57a.

As described above, since the tunnel insulating layer 56 is in contact with the lower surface of the second ferromagnetic layer 57a, the tunnel insulating layer 56 is etched by etching the first and second ferromagnetic layers and the tunnel insulating layer therebetween. It is possible to prevent the problem that the damage or the foreign matter attached to lose the original characteristics of the insulating film in advance.

In addition, an additional electrode material may be formed on the second ferromagnetic material before the planarization process to fill the space from which the sacrificial film is removed.

Thereafter, the bit line 58 is formed in one line direction that is in contact with the tunnel insulating layer 56 and the second ferromagnetic layer 57a and is orthogonal to the word line 51.

Second embodiment

Hereinafter, a magnetic random access memory device and a method of manufacturing the same according to a second embodiment of the present invention will be described with reference to the accompanying drawings.

5 is a structural cross-sectional view of a magnetic random access memory device including an MTJ cell according to a second embodiment of the present invention, and FIGS. 6A to 6E are magnetic random access memory devices including an MTJ cell according to a second embodiment of the present invention. The process cross section which shows the manufacturing method of.

The magnetic tunnel junction cell of the magnetic random access memory device according to the second embodiment of the present invention has a word line 61 arranged in one direction on the substrate 60, as shown in FIG. The first interlayer insulating film 62 is formed on both sides of the substrate 60 so that the top thereof is exposed.

In addition, a first ferromagnetic layer 63 is formed on one region (cell region) of the word line 61, and a tunnel insulating layer 67 and a second ferromagnetic layer 68a are formed on the first ferromagnetic layer 63. Formed.

In this case, the tunnel insulating layer 67 is formed to surround the lower surface and the side surface of the second ferromagnetic layer 68a.

Sidewall spacers 65 are formed on both sides of the first ferromagnetic film 63 and the tunnel insulating film 67, and the entire surface of the substrate 60 is removed except for the upper portions of the tunnel insulating film 67 and the second ferromagnetic film 68a. A second interlayer insulating film 66 is formed on the substrate.

The bit line 69 is arranged in contact with the upper portion of the tunnel insulating layer 67 and the second ferromagnetic layer 68a and orthogonal to the word line 61.

In the method of manufacturing the magnetic random access memory device according to the second embodiment of the present invention having the above structure, the word lines 61 are formed on the substrate 60 so as to be arranged in one line direction. do.

Thereafter, a first interlayer insulating layer 62 is deposited on the entire surface of the substrate 60 including the word line 61.

The first interlayer insulating layer 62 is planarized to expose the upper portion of the word line 61 by a chemical mechanical polishing (CMP) process.

Subsequently, the first ferromagnetic material and the sacrificial film are sequentially deposited on the first interlayer insulating layer 62 including the word line 61, and then the sacrificial film and the first ferromagnetic material are sequentially dry-etched by a photo process, and then the first ferromagnetic material is etched in the cell region. The ferromagnetic film 63 and the sacrificial film 64 are laminated.

In this case, the first ferromagnetic material uses an oxide ferromagnetic material, and the sacrificial film 64 uses a material that does not contain oxygen such as TiN.

Next, as shown in FIG. 6B, an insulating film is deposited on the entire surface of the substrate 60 including the first ferromagnetic film 63 and the sacrificial film 64, and then etched back to form the first ferromagnetic film 63 and the sacrificial film 64. Sidewall spacers 65 are formed on both sides of the substrate.

At this time, the sidewall spacer 65 is an oxygen blocking layer for protecting the MTJ cell in an oxidizing atmosphere, and is formed using a material such as SiN.

Subsequently, a second interlayer insulating layer 66 is deposited on the entire surface of the substrate 60 including the first ferromagnetic layer 63, the sacrificial layer 64, and the sidewall spacers 65.

The second interlayer insulating film 66 is planarized to expose the sacrificial film 64 by a chemical mechanical polishing process.

As shown in FIG. 6C, only the sacrificial layer 64 is selectively removed by wet etching to form grooves on the first ferromagnetic layer 63 as much as the cell region.

When the sacrificial layer 64 is wet-etched and removed as described above, the first ferromagnetic layer 63 may be partially oxidized to reduce the TMR (Tunneling Magneto-Resistance) characteristics. Thus, the surface may be dried. The surface of the oxidized first ferromagnetic film 63 is partially removed.

Thereafter, the tunnel insulating film 67 is deposited in-situ continuously as shown in FIG. 6D.

At this time, since the oxide ferromagnetic material is used as the first ferromagnetic film 63, the problem of oxidizing the first ferromagnetic film 63 during the air exposure or the wet process can be prevented.

Next, a second ferromagnetic material 68 is deposited on the tunnel insulating film 67 including the grooves on the first ferromagnetic film 63.

Subsequently, as shown in FIG. 6E, the second ferromagnetic material 68 and the tunnel insulating layer 67 are etched back to expose the second interlayer insulating layer 66 to divide the magnetic tunnel junction cell into cell units. In addition, the tunnel insulating film 67 and the second ferromagnetic film 68a are formed in the grooves above the first ferromagnetic film 63 by planarization by a chemical mechanical polishing (CMP) process.

By such a process, the tunnel insulating film 67 covers the lower surface and the side surface of the second ferromagnetic film 68a.

As described above, since the tunnel insulating layer 67 is in contact with the lower surface of the second ferromagnetic layer 68a, the tunnel insulating layer is etched by etching the first and second ferromagnetic layers and the tunnel insulating layer therebetween. It is possible to prevent the problem that the damage or the foreign matter attached to lose the original characteristics of the insulating film in advance.

The additional electrode material may be formed on the second ferromagnetic material before the planarization process to fill the space from which the sacrificial film is removed.

Thereafter, the bit line 69 is formed to be in contact with the tunnel insulating layer 67 and the second ferromagnetic layer 68a and to be aligned in one line direction perpendicular to the word line 61.

The present invention is not limited to the above embodiments, and includes various forms that can be easily derived by those skilled in the art from the above embodiments.

The magnetic random access memory (MRAM) device of the present invention as described above and a manufacturing method thereof have the following effects.

First, since the first and second ferromagnetic films are not adjacent to the portions of the tunnel insulating layer, the problem of changing the characteristics of the tunnel insulating layer due to etching damage or adhesion of foreign matters can be prevented. have.

Second, by providing sidewall spacers on both sides of the first ferromagnetic film and the tunnel insulating film, the MTJ cell can be protected in an oxidizing atmosphere.

Claims (13)

Word lines arranged in one direction on the substrate; A first ferromagnetic film formed on one region of the word line; A second ferromagnetic film formed on the first ferromagnetic film; A tunnel insulating film formed on the first ferromagnetic film to surround a lower surface and a side surface of the second ferromagnetic film; And a bit line in contact with the tunnel insulating film and the second ferromagnetic film and arranged in a direction orthogonal to the word line. The magnetic random access memory device of claim 1, further comprising sidewall spacers on both sides of the first ferromagnetic layer and the tunnel insulation layer. 2. The magnetic random access memory device of claim 1, further comprising a first interlayer insulating film on the substrate on both sides of the word line. 2. The magnetic random access memory device of claim 1, further comprising a second interlayer insulating film on both sides of the first ferromagnetic film and the tunnel insulating film. Forming a word line to be arranged in one direction on the substrate; Stacking a first ferromagnetic layer and a sacrificial layer on one region of the word line; Depositing and planarizing an interlayer insulating film on both sides of the first ferromagnetic film and the sacrificial film; Removing the sacrificial layer to form a groove on the first ferromagnetic layer; Forming a tunnel insulating film in a groove on the first ferromagnetic film, and simultaneously forming a second ferromagnetic film having a lower surface and a side surface covered by the tunnel insulating film; And forming a bit line in contact with the tunnel insulating film and the second ferromagnetic film and arranged in a direction orthogonal to the word line. The method of claim 5, wherein the tunnel insulating film and the second ferromagnetic film is formed, Sequentially depositing an insulating film and a ferromagnetic material on the interlayer insulating film including the grooves on the first ferromagnetic film; Planarizing the ferromagnetic material and the insulating film so that an upper portion of the interlayer insulating film is exposed. 7. The method of claim 6, wherein the planarization uses a chemical mechanical smoke deposition process or an etch back process. 6. The method of claim 5, further comprising forming sidewall spacers on both sides of the first ferromagnetic film and the sacrificial film before forming the interlayer insulating film. 6. The method of claim 5, further comprising dry etching the surface of the first ferromagnetic film by a predetermined amount after selectively removing the sacrificial film. 6. The method of claim 5, wherein the sacrificial film is formed of a film containing no oxygen such as a TiN film. The method of claim 5, wherein the sacrificial layer is removed by wet etching. 6. The method of manufacturing a magnetic random access memory device according to claim 5, wherein the tunnel insulating film is formed of an Al2O3 film. 9. The method of claim 8, wherein the sidewall spacer is formed of SiN.