WO2006100779A1

WO2006100779A1 - Magnetic memory device and method for manufacturing same

Info

Publication number: WO2006100779A1
Application number: PCT/JP2005/005390
Authority: WO
Inventors: Chikako Yoshida; Osamu Shimizu
Original assignee: Fujitsu Limited
Priority date: 2005-03-24
Filing date: 2005-03-24
Publication date: 2006-09-28

Abstract

A magnetic memory device is provided with a first magnetic layer (66) formed on a substrate (10); a tunnel insulating film (68) formed on the first magnetic layer (66); a second magnetic layer (74) formed on the tunnel insulating film (68); and a magnetic resistor element (52) having an electrode (78) formed on the second magnetic layer (74). Further, the magnetic memory device is provided with a ruthenium film (76) formed between the second magnetic layer (74) and the electrode (78). Since the ruthenium film is formed between the second magnetic layer and the electrode, the ruthenium film functions as an etching stopper at the time of forming the electrode by etching a conductive layer. The ruthenium film formed between the second magnetic layer and the electrode also functions as a diffusion preventing film for preventing mutual diffusion of atoms composing the second magnetic layer and atoms composing the electrode, in heat treatment for matching spinning directions in the first magnetic layer or the second magnetic layer. Therefore, the magnetic memory device having a fine magnetic resistor element can be manufactured at a high yield.

Description

Specification

Magnetic memory device and manufacturing method thereof

Technical field

The present invention relates to a magnetic memory device and a manufacturing method thereof, and more particularly, to a magnetic memory device having a magnetoresistive element and a manufacturing method thereof.

Background art

In recent years, a magnetic random access memory (hereinafter referred to as MRAM: Magnetic Random Access Memory) in which magnetoresistive elements are arranged in a matrix is drawing attention as a rewritable nonvolatile memory. MRAM stores information using a combination of magnetization directions in two magnetic layers, and changes in resistance (i.e., current or current) when the magnetic directions between these magnetic layers are parallel and antiparallel. The stored information is read by detecting the voltage change).

As a magnetoresistive element constituting MRAM, a magnetic tunnel junction (hereinafter referred to as MTJ: Magnetic)

A device called Tunnel Junction is known. An MTJ element has two ferromagnetic layers stacked via a tunnel insulating film, and the tunnel current that flows through the tunnel insulating film is based on the relationship between the magnetic directions of the two ferromagnetic layers. It uses a changing phenomenon. That is, the MTJ element has a low element resistance (low resistance state) when the magnetic directions of the two ferromagnetic layers are parallel, and has a high element resistance (high resistance state) when the two ferromagnetic layers are antiparallel. By associating these two states with data “0” and data “1”, they can be used as a memory element.

A proposed method for manufacturing a magnetic memory device will be described with reference to FIG. FIG. 10 is a process cross-sectional view illustrating the proposed method of manufacturing a magnetic memory device.

First, as shown in FIG. 10A, a conductive layer 154, an antiferromagnetic layer 158, a fixed layer 166, a tunnel insulating film 168, a free layer 174, and a conductive layer 178 are sequentially formed on a substrate 110. . Thus, a laminated film 179 including the conductive layer 154, the antiferromagnetic layer 158, the fixed layer 166, the tunnel insulating film 168, the free layer 174, and the conductive layer 178 is formed. The conductive layer 154 serves as the lower electrode of the MTJ element 152, and the conductive layer 176 serves as the upper electrode of the MTJ element 152. Next, a photoresist film 186 is formed on the conductive layer 178. Thereafter, the photoresist film 186 is patterned using photolithography technology.

Next, as shown in FIG. 10B, the laminated film 179 is etched by argon ion milling using the photoresist film 186 as a mask until the surface of the conductive layer 154 is exposed. In this way, an MTJ element (magnetoresistance element) 152 is formed.

[0008] Note that the background art of the present invention includes the following.

Patent Document 1: Japanese Patent Laid-Open No. 11-92971

Patent Document 2: JP 2002-76470 A

Patent Document 3: Japanese Patent Laid-Open No. 2003-31776

Patent Document 4: Japanese Patent No. 2677321

Patent Document 5: JP 2000-322710 A

Patent Document 6: Japanese Patent Laid-Open No. 2002-38285

Non-Patent Document 1: Noriyuki Fukumoto, Hideaki Numata, Katsumi Suemitsu, Seigo Nagahara, Norikazu Oshima, Hiromitsu Hata, Shuichi Tahara, Minoru Amano, Yoshiaki Asao, Hiroaki Kajita, `` High heat resistance NiXFel-X / Al-oxide / Magnetization reversal characteristics of ferromagnetic tunnel junctions using Ta-free layers ", 28th Annual Meeting of the Japan Society of Applied Magnetics, 2004, p. 218

Non-Patent Document 2: GH Yu, HC Zhao, MH Li, and FW Zhu, "Interface reaction of Ta / Ni81Fel9or Ni81Fel9 / Ta and its suppression", Applied Physics Letters, Volume 80, Number 3, 21 January (2002), p . 455-457

Disclosure of the invention

Problems to be solved by the invention

When the laminated film 179 is etched by ion milling with a force, the material of the laminated film 1 79 reattaches to the side surface of the etched laminated film 179, and the free layer 166 and the fixed layer 1 74 May be short-circuited. A force that has been devised to make the ions incident obliquely to remove the material reattached to the side wall. In this case, it becomes difficult to achieve uniform processing and high density of elements. In addition, when the laminated film 179 is etched by ion milling, the selectivity of the laminated film 179 with respect to the photoresist film 186 is not necessarily high enough, so that the photoresist film 186 must be formed very thick. I got it. F The fact that the photoresist film 186 has to be formed very thick has been an impediment to miniaturization of the magnetoresistive element. In addition, when the laminated film 179 is etched by ion milling, the sputtering speed varies depending on the incident angle of ions (depending on the incident angle of the sputtering rate), so the laminated film is etched perpendicular to the wafer surface. Is difficult. This has also been an impediment to miniaturization of magnetoresistive elements.

An object of the present invention is to provide a magnetic memory device capable of forming fine magnetoresistive elements with a high yield, and a method for manufacturing the same.

Means for solving the problem

[0011] According to one aspect of the present invention, a first magnetic layer formed on a substrate; a tunnel insulating film formed on the first magnetic layer; and formed on the tunnel insulating film A magnetic memory device having a second magnetic layer; and a magnetoresistive element having an electrode formed on the second magnetic layer, the ruthenium formed between the second magnetic layer and the electrode A magnetic memory device further comprising a film is provided.

[0012] According to another aspect of the present invention, a step of forming a first magnetic layer on a substrate, a step of forming a tunnel insulating film on the first magnetic layer, and the tunnel insulating film A step of forming a second magnetic layer thereon, a step of forming a ruthenium film on the second magnetic layer, a step of forming a conductive layer on the ruthenium film, and a photoresist mass on the conductive layer. Using the photoresist mask, using the ruthenium film as an etching stopper, etching the conductive layer to form an electrode made of the conductive layer, and using the electrode as a mask, There is provided a method of manufacturing a magnetic memory device including a step of etching at least the ruthenium film and the second magnetic layer. The invention's effect

According to the present invention, since the ruthenium film is formed between the second magnetic layer and the electrode, the ruthenium film functions as an etching stopper when the electrode is formed by etching the conductive layer. Therefore, according to the present invention, it is possible to prevent receiving the second free layer damage when etching the conductive layer. Also, since the conductive layer is etched using the ruthenium film as an etching stopper, the patterning of the conductive layer can be performed uniformly in the wafer surface. Therefore, according to the present invention, the magnetoresistive element can be manufactured at a high yield. Can be formed.

Further, according to the present invention, since the second magnetic layer and the like are patterned using the electrode as a mask, it is not necessary to form a very thick photoresist film. Since it is not necessary to form a very thick photoresist film, the photoresist film can be finely patterned. Therefore, according to the present invention, the magnetoresistive element can be formed finely.

[0015] According to the present invention, since the ruthenium film functions as an etching stopper, it is not necessary to detect the end point of etching using a plasma spectroscopic analyzer or the like. For this reason, according to the present invention, the conductive layer can be patterned easily and reliably.

Further, according to the present invention, the ruthenium film formed between the second magnetic layer and the electrode is subjected to heat treatment when aligning the spin direction in the first magnetic layer or the second magnetic layer. It also functions as a diffusion prevention film (barrier film) that prevents the atoms constituting the second magnetic layer and the atoms constituting the electrode from interdiffusion. Therefore, according to the present invention, the ruthenium film can prevent the atoms constituting the electrode and the atoms constituting the first magnetic layer from interdiffusion.

As described above, according to the present invention, a magnetic memory device having a minute magnetoresistive element can be manufactured with a high yield.

Brief Description of Drawings

FIG. 1 is a cross-sectional view showing a magnetic memory device according to an embodiment of the present invention.

FIG. 2 is a process sectional view showing the method for manufacturing the magnetic memory device according to the embodiment (part 2).

1).

FIG. 3 is a process sectional view showing the method for manufacturing the magnetic memory device according to the embodiment (part 3).

2).

FIG. 4 is a process sectional view showing the method for manufacturing the magnetic memory device according to the embodiment (part 4).

3).

FIG. 5 is a process sectional view showing the method for manufacturing the magnetic memory device according to the embodiment (part 1).

4).

FIG. 6 is a process sectional view showing the method for manufacturing the magnetic memory device according to the embodiment (part 6).

5). [FIG. 7] FIG. 7 is a graph (No. 1) showing a concentration profile in the depth direction obtained by Auger electron spectroscopy.

[FIG. 8] FIG. 8 is a graph (part 2) showing the concentration profile in the depth direction obtained by the Auger electron spectroscopy.

FIG. 9 is a graph showing a magnetic field curve measured by a sample vibration type magnetometer.

FIG. 10 is a process sectional view showing the proposed method for manufacturing a magnetic memory device.

FIG. 11 is a process cross-sectional view showing a case where a laminated film is etched by the RIE method. Explanation of symbols

10 ··· Semiconductor substrate

12 ··· Gate insulation film

14… Gate electrode (read word line)

16a, 16b ... Source Z Drain region

18 · "Transistor

20… Interlayer insulation film

22 ··· Contact hole

24… Conductor plug

26… Interlayer insulation film

28a, 28b ... groove

30a… Conductive layer

30b ... Ground layer

32… Interlayer insulation film

34 ··· Contact hole

36… Conductor plug

38… Interlayer insulation film

40a, sumi… groove

41a… Conductive layer

41b ... Write word line 42 ··· NiFe film, cladding layer

44 · • Cu film

46 ··-Interlayer insulation film

48 ·· 'Contact hole

50 ··-Conductor plug

52 · · · magnetoresistive element

54-Conductive layer, lower electrode

• NiNi film

58 ... Antiferromagnetic layer

60 ... 'Ferromagnetic layer

62 ...- Non-magnetic layer

64 ...- Ferromagnetic layer

66--Fixed layer

68 'Tunnel insulation film

70 ...- Ferromagnetic layer

72 ...-Ferromagnetic layer

74 ...-Free layer

76 ... Ruthenium film

78--Conductive layer, upper electrode

80 ...-Interlayer insulation film

82 ·· 'Contact hole

84-Bit line

86 ·· • Photoresist film

110… Board

152 · '· Qi IS

154 ... Conductive layer, lower electrode

158 ... Antiferromagnetic layer

166 '... fixed layer 168 ... Tunnel insulating film

174 ··· Free layer

178… Conductive layer, upper electrode

179 ··· Laminated film

186 ... Photoresist film

BEST MODE FOR CARRYING OUT THE INVENTION

As described above, when the laminated film 179 is etched by ion milling, the etched material of the laminated film 179 reattaches to the side surface of the laminated film 179, and the free layer 166 and the fixed layer 174 May be short-circuited. In addition, when the laminated film 179 is etched by ion milling, the selectivity of the laminated film 179 with respect to the photoresist film 186 is not necessarily high enough, so that it is necessary to form the photoresist film 186 sufficiently thick. I got it. The fact that the photoresist film 186 had to be formed sufficiently thick was an obstacle to miniaturization of the magnetoresistive element. In addition, when the laminated film 179 is etched by ion milling, the sputtering speed varies depending on the incident angle of ions (depending on the incident angle of the sputtering rate). Is difficult. This has also been an impediment to miniaturization of magnetoresistive elements.

[0021] Here, etching of the laminated film using the RIE (Reactive Ion Etching) method is also considered.

FIG. 11 is a process cross-sectional view showing the case where the laminated film is etched by the RIE method.

First, as shown in FIG. 11 (a), a conductive layer 154, an antiferromagnetic layer 158, a fixed layer 166, a tunnel insulating film 168, a free layer 174, and a conductive layer 178 are sequentially formed on a substrate 110. . Thus, a laminated film 179 including the conductive layer 154, the antiferromagnetic layer 158, the fixed layer 166, the tunnel insulating film 168, the free layer 174, and the conductive layer 178 is formed. The conductive layer 154 serves as the lower electrode of the magnetoresistive element, and the conductive layer 176 serves as the upper electrode of the magnetoresistive element.

Next, a photoresist film 186 is formed on the conductive layer 178. Thereafter, the photoresist film 186 is patterned using photolithography technology.

Next, as shown in FIG. 11B, the conductive layer 178 is etched by the RIE method using the photoresist film 186 as a mask. As the etching gas, for example, a halogen-based gas is used. o In this way, an upper electrode made of the conductive layer 178 is formed.

Next, as shown in FIG. 11 (c), the free layer 174, the tunnel insulating film 168, the fixed layer 166, by the RIE method using the upper electrode 178 as a hard mask and the conductive layer 154 as an etch stopper. The antiferromagnetic layer 158 is anisotropically etched. For example, a mixed gas of CO gas and NH gas is used as the etching gas. The end point of etching is, for example, a plasma spectrometer

Three

To detect.

[0027] Even when the laminated film 179 is etched using the RIE method, the material of the etched laminated film 179 reattaches to the sidewall of the laminated film 179, but does not adhere to the sidewall of the laminated film 179. The kimono is removed as follows. That is, using a mixed gas of CO gas and NH gas

Three

When the laminated film 179 is anisotropically etched, the laminated film 179 is etched in a direction substantially perpendicular to the substrate surface, and the lower electrode 154 functioning as an etching stopper is exposed. After the laminated film 179 is etched and the lower electrode 154 is exposed, the laminated film 179 that is a raw material of the deposit is not etched, so that the material of the laminated film 179 may be reattached to the side wall of the laminated film 179. Disappear. Deposits adhering to the side walls of the laminated film 179 are gradually removed by etching. In this manner, if the laminated film 179 is etched using the RIE method, it is possible to prevent the free layer 174 and the fixed layer 166 from being short-circuited. Further, since the free layer 174 and the like are etched using the upper electrode 178 as a node mask, it is not necessary to form the photoresist film 186 very thick. Further, when the laminated film 179 is etched using the RIE method, the laminated film 179 can be etched almost perpendicularly to the wafer surface. Therefore, if the etching is performed using the RIE method, the magnetoresistive element 152 can be miniaturized.

[0028] However, since a halogen-based gas is used when etching the conductive layer 178 using the RIE method, the halide force generated during the etching is applied to the side wall of the upper electrode 178 and the surface of the free layer 174. It may adhere. If halogenated substances adhere to the side walls of the upper electrode 178 or the surface of the free layer 174, the adhered halogenated substances may react with the wiring material, resulting in corrosion of the wiring (after-corrosion). For this reason, it is difficult to form a magnetoresistive element with a sufficiently high yield.

In addition, when the conductive layer 178 is etched to form the upper electrode, plasma spectroscopic analysis is performed. Force to detect the end point of etching using an apparatus It is not always easy to stop etching accurately when the surface of the free layer 174 is exposed. When the free layer 174 is exposed to a halogen-based gas, the free layer 174 is damaged, making it difficult to obtain a magnetoresistive element having good characteristics.

[0030] Further, since the etching rate is not necessarily uniform within the wafer surface, it is not always easy to pattern the conductive layer 178 uniformly within the wafer surface.

[0031] As a result of intensive studies, the inventors of the present application have come up with the idea of forming a ruthenium film between the free layer and the conductive layer (upper electrode).

According to the present invention, since the ruthenium film is formed between the free layer and the conductive layer (upper electrode), when the upper electrode is formed by etching the conductive layer, the ruthenium film is used as an etching stopper. It becomes possible to etch the layer. Therefore, the ruthenium film can prevent the free layer from being damaged by being exposed to the halogen-based gas used when etching the conductive layer. In addition, since the ruthenium film functions as an etching stopper when the conductive layer is etched to form the upper electrode, the conductive layer can be patterned uniformly. Therefore, according to the present embodiment, a magnetic memory device having a fine magnetic resistance element can be manufactured with a high yield.

[0033] According to the present invention, the ruthenium film formed between the free layer and the conductive layer (upper electrode) is heat-treated while applying a magnetic field to align the spin direction in the fixed layer. At this time, it also functions as a diffusion prevention film (barrier film) that prevents the atoms constituting the free layer and the atoms constituting the upper electrode from interdiffusion. Therefore, according to the present invention, it is possible to provide a magnetic memory device having a magnetoresistive element with better characteristics.

[0034] [One Embodiment]

A magnetic memory device and a manufacturing method thereof according to an embodiment of the present invention will be described with reference to FIGS.

[0035] (Magnetic memory device)

First, the magnetic memory device according to the present embodiment will be explained with reference to FIG. FIG. 1 is a sectional view of the magnetic memory device according to the present embodiment. Figure 1 (a) is according to this embodiment. It is sectional drawing which shows the structure of a magnetic memory device. FIG. 1B is a cross-sectional view showing a part of the magnetic memory device according to the present embodiment.

As shown in FIG. 1, a gate electrode (read word line) 14 is formed on a semiconductor substrate 10 via a gate insulating film 12. As the semiconductor substrate 10, for example, a silicon substrate is used.

In the semiconductor substrate 10 on both sides of the gate electrode 14, source Z drain regions 16a and 16b are formed. Thus, the transistor 18 having the gate electrode 14 and the source / drain regions 16a and 16b is formed.

An interlayer insulating film 20 is formed on the semiconductor substrate 10 on which the transistor 18 is formed. In the interlayer insulating film 20, contact holes 22 reaching the source Z drain regions 16a and 16b are formed. A conductor plug 24 is embedded in the contact hole 22.

An interlayer insulating film 26 is formed on the interlayer insulating film 20 in which the conductor plugs 24 are embedded. In the interlayer insulating film 26, grooves 28a and 28b are formed. The groove 28a is for embedding the conductive layer 28a. The groove 28b is for embedding the wiring 30b. The upper surface of the conductor plug 24 is exposed in the grooves 28a and 28b.

[0040] A conductive layer 30a is embedded in the groove 28a. The conductive layer 30a is connected to the conductor plug 24. A wiring (ground line) 30b is embedded in the groove 28b. Wiring 3 Ob functions as a ground line. The ground line 30b is electrically connected to the source / drain region 16b of the transistor 18 through the conductor plug 24 !.

An interlayer insulating film 32 is formed on the interlayer insulating film 26 in which the conductive layer 30a and the wiring 30b are embedded. A contact hole 34 reaching the conductive layer 30a is formed in the interlayer insulating film 32. A conductor plug 36 is embedded in the contact hole 34. The conductor plug 36 is connected to the conductive layer 30a.

An interlayer insulating film 38 is formed on the interlayer insulating film 32 in which the conductor plugs 36 are embedded. Grooves 40 a and 40 b are formed in the interlayer insulating film 38. In the groove 40a, the upper surface of the conductor plug 36 is exposed!

[0043] A conductive layer 41a is embedded in the groove 40a. The conductive layer 41a is connected to the conductor plug 36. A wiring (write word line) 41b is embedded in the groove 40b. The conductive layer 41 a and the write word line 41 b are each composed of a laminated film composed of a Ta (tantalum) film (not shown), a NiFe film 42, and a Cu (copper) film 44. The Ta film functions as a barrier metal film. The NiFe film 42 functions as a cladding layer for obtaining a strong magnetic field when writing.

An interlayer insulating film 46 having a film thickness of lOOnm is formed on the interlayer insulating film 38 in which the conductive layer 41a and the write word line 41b are embedded.

In the interlayer insulating film 46, a contact hole 48 reaching the conductive layer 41a is formed. A conductor plug 50 is embedded in the contact hole 48. The conductor plug 50 is electrically connected to the conductive layer 41a.

A lower electrode 54 of the magnetoresistive element 52 is formed on the interlayer insulating film 46 in which the conductor plug 50 is embedded. As a material of the lower electrode 54, for example, a Ta film is used. The lower electrode 54 is electrically connected to the source / drain region 16a of the transistor 18 through the conductor plug 50, the conductive layer 41a, the conductor plug 36, the conductive layer 30a, and the conductor plug 24.

A NiFe film 56 is formed on the lower electrode 54. The NiFe film 56 is for forming an antiferromagnetic layer 58 with good crystallinity on the upper side.

[0049] On the NiFe film 56, an antiferromagnetic layer 58 made of a PtMn film is formed.

[0050] On the antiferromagnetic layer 58, a ferromagnetic layer 60 made of a CoFe film is formed. On the ferromagnetic layer 60, a nonmagnetic layer 62 made of a Ru film is formed. A ferromagnetic layer 64 made of a CoFe film is formed on the nonmagnetic layer 62. The ferromagnetic layer 60, the nonmagnetic layer 62, and the ferromagnetic layer 64 constitute a fixed layer (first magnetic layer) 66 of the magnetoresistive element 52.

[0051] On the fixed layer 66, a tunnel insulating film 68 made of an alumina (AIO) film is formed.

X

[0052] C on the tunnel insulating film 68; A ferromagnetic layer 70 made of an Fe film is formed. On the ferromagnetic layer 70, a ferromagnetic layer 72 made of a NiFe film is formed. The ferromagnetic layer 70 and the ferromagnetic layer 72 constitute a free layer (second magnetic layer) 74 of the magnetoresistive element 52.

A Ru (ruthenium) film 76 is formed on the free layer 74. As will be described later, the Ru film 76 functions as an etching stopper film. The Ru film 76 will be described later. In other words, it also functions as a diffusion preventing film (barrier film).

An upper electrode (cap layer) 78 is formed on the Ru film 76. As a material of the upper electrode 78, for example, a Ta film is used. The upper electrode 78 also functions as a hard mask when the free layer 76 and the like are etched.

Thus, a magnetoresistive element (MTJ element) 52 including the lower electrode 54, the antiferromagnetic layer 58, the fixed layer 66, the tunnel insulating film 68, the free layer 74, the Ru film 76, and the upper electrode 78 is formed.

An interlayer insulating film 80 is formed on the interlayer insulating film 46 on which the magnetoresistive element 52 is formed.

A contact hole 82 reaching the upper electrode 78 is formed in the interlayer insulating film 80.

A bit line 84 is formed in the contact hole 82 and on the interlayer insulating film 80. The bit line 84 is connected to the upper electrode 78 of the magnetoresistive element 52.

Thus, the magnetic memory device according to the present embodiment is constituted.

The magnetic memory device according to the present embodiment is mainly characterized in that a Ru film 76 is formed between the free layer 74 and the upper electrode 78.

[0060] According to the present embodiment, since the Ru film 76 is formed between the free layer 74 and the upper electrode 78, the conductive layer 78 is etched to form the upper electrode, as will be described later. In this case, the Ru film 76 functions as an etching stopper. Therefore, according to the present embodiment, it is possible to prevent the free layer 74 from being damaged when the conductive layer 78 is etched. However, since the conductive layer 78 is etched using the Ru film 76 as an etching stopper, the patterning of the conductive layer 78 can be performed uniformly in the wafer surface. Therefore, according to the present embodiment, the magnetoresistive element can be formed with a high yield.

Further, according to the present embodiment, since the free layer 74 and the like are patterned using the upper electrode 78 as a mask, it is not necessary to form the photoresist film 86 very thickly. Since it is not necessary to form the photoresist film 86 very thickly, the photoresist film 86 can be finely patterned. Therefore, according to the present embodiment, the magnetoresistive element can be formed finely.

Further, according to the present embodiment, as will be described later, the Ru film 76 serves as an etching stopper. Therefore, it is not necessary to detect the end point of etching using a plasma spectroscopic analyzer or the like. Therefore, according to the present embodiment, the conductive layer 78 can be patterned easily and reliably.

Further, according to the present embodiment, the Ru film 76 formed between the free layer 74 and the upper electrode 78 is self-treated in the heat treatment when aligning the spin direction in the fixed layer 66 as described later. It also functions as a diffusion prevention film (noria film) that prevents mutual diffusion between the constituent atoms of the base layer 76 and the constituent atoms of the upper electrode 78. For this reason, according to the present embodiment, the Ru film 76 can prevent the atoms constituting the upper electrode 78 and the atoms constituting the free layer 76 from interdiffusion.

As described above, according to this embodiment, a magnetic memory device having a minute magnetoresistive element can be manufactured at a high yield.

Next, the operation of the magnetic memory device according to the present embodiment will be explained with reference to FIG.

[0066] When data is written to the magnetoresistive element 52, currents are passed through the bit line 84 and the write word line 41b, respectively. When the thickness of the interlayer insulating film 46 is, for example, about lOOnm, and the current passed through the bit line 84 and the write word line 41b is, for example, about 1 mA, a magnetic field of, for example, about 70-80 (Oe) is generated. The magnetic field necessary to invert the spin of the free layer 74 is, for example, about 50 (Oe). Thus, data can be written to the magnetoresistive element 52.

When reading data written in the magnetoresistive element 52, a voltage is applied to the read word line 14, and a current is passed through the bit line 84 with the transistor 18 turned on. Since the current flowing through the bit line 84 differs depending on the data written to the magnetoresistive element 52, the data written to the magnetoresistive element 52 can be read.

[0068] (Method for Manufacturing Magnetic Memory Device)

Next, the method for manufacturing the magnetic memory device according to the present embodiment will be explained with reference to FIGS. 2 to 6 are process cross-sectional views illustrating the method of manufacturing the magnetic memory device according to the present embodiment.

First, as shown in FIG. 2A, a transistor 18 having a gate electrode 14 and source Z drain regions 16a and 16b is formed on a semiconductor substrate 10. For example, the semiconductor substrate 10 For example, a silicon substrate is used.

Next, an interlayer insulating film 20 made of a silicon oxide film having a thickness of lOOOnm is formed on the entire surface by, eg, CVD.

Next, the surface of the interlayer insulating film 20 is planarized by, eg, CMP.

Next, a contact hole 22 reaching the source Z drain regions 16a and 16b is formed in the interlayer insulating film 20 by using a photolithography technique.

Next, a 30 nm-thickness Ti film (not shown) is formed on the entire surface by, eg, sputtering.

Next, a TiN film (not shown) having a thickness of lOnm is formed on the entire surface by, eg, CVD.

. Thus, a barrier metal film (not shown) made of a Ti film and a TiN film is formed.

Next, a 300 nm-thickness tungsten film is formed on the entire surface by, eg, CVD.

Next, the tungsten film and the barrier metal film are polished by, for example, a CMP method until the surface of the interlayer insulating film 20 is exposed. Thus, the conductor plug 24 made of a tungsten film or the like is embedded in the contact hole 22.

Next, an interlayer insulating film 26 made of a silicon oxide film having a thickness of 300 nm is formed on the entire surface by, eg, CVD.

Next, the surface of the interlayer insulating film 26 is flattened by, eg, CMP.

Next, trenches 28 a and 28 b are formed in the interlayer insulating film 26 by using a photolithography technique. Groove 2

8a is for embedding the conductive layer 30a. The groove 28b is for embedding the ground line 30b.

Next, a seed layer (not shown) is formed on the entire surface by, eg, sputtering.

Next, a 600 nm-thickness Cu film is formed on the entire surface by, eg, electroplating.

Next, the Cu film and the seed layer are polished by, for example, a CMP method until the surface of the interlayer insulating film 26 is exposed. Thus, the conductive layer 30a made of a Cu film or the like is buried in the groove 28a, and the ground line 30b made of the Cu film or the like is buried in the groove 28b.

Next, an interlayer insulating film 32 made of a silicon oxide film having a thickness of 200 nm is formed on the entire surface by, eg, CVD.

Next, the surface of the interlayer insulating film 32 is planarized by, eg, CMP. Next, a contact hole 34 reaching the conductive layer 30a is formed in the interlayer insulating film 32 by using a photolithography technique.

Next, a 20 nm-thick TiN film (not shown) is formed on the entire surface by, eg, CVD.

Next, the tungsten film and the barrier metal film are polished by, eg, CMP method until the surface of the interlayer insulating film 32 is exposed. Thus, the conductor plug 36 made of a tungsten film or the like is embedded in the contact hole 34.

Next, an interlayer insulating film 38 made of a silicon oxide film having a thickness of 400 nm is formed on the entire surface by, eg, CVD.

Next, the surface of the interlayer insulating film 38 is planarized by, eg, CMP.

Next, grooves 40a and 40b are formed in the interlayer insulating film 38 by photolithography. Groove 4

Oa is for embedding the conductive layer 41a. The groove 40b is for embedding the write word line 41b.

Next, a 20 nm-thickness Ta film (not shown) is formed on the entire surface by, eg, sputtering.

. The Ta film functions as a noria metal film.

Next, a 50 nm-thickness NiFe film 42 is formed on the entire surface by, eg, sputtering. The NiFe film 42 functions as a clad layer for obtaining a strong magnetic field when writing.

Next, a Cu film 44 having a film thickness of 800 nm is formed by an electroplating method.

Next, the Cu film 44, the NiFe film 42, and the Ta film are polished by, for example, CMP until the surface of the interlayer insulating film 38 is exposed. Thus, the conductive layer 4 la made of the Cu film 44 or the like is buried in the groove 40a, and the write word line 41b made of the Cu film 44 or the like is buried in the groove 40b.

Next, as shown in FIG. 2B, an interlayer insulating film 46 is formed on the entire surface by, eg, CVD. Next, a contact hole 48 that reaches the conductive layer 41 a is formed in the interlayer insulating film 46 by using a photolithography technique.

Next, a 30 nm-thick Ti film (not shown) is formed on the entire surface by, eg, sputtering.

Next, a TiN film (not shown) having a thickness of 20 nm is formed by, eg, CVD. Thus, a barrier metal film (not shown) made of a Ti film and a TiN film is formed.

Next, a 300 nm-thickness tungsten film is formed by, eg, CVD.

Next, the tungsten film and the barrier metal film are polished by CMP, for example, until the surface of the interlayer insulating film 46 is exposed. In this way, the conductor plug 50 made of tungsten or the like is embedded in the contact hole 48.

Next, as shown in FIG. 3 (a), a conductive layer 54 made of a Ta film is formed on the entire surface by, eg, sputtering. The conductive layer 54 becomes a lower electrode of the magnetoresistive element 52. In FIG. 3A, the components existing below the interlayer insulating film 46 are omitted.

Next, a NiFe film 56 having a thickness of 2 nm is formed by, eg, sputtering. The NiFe film 56 is for forming an antiferromagnetic layer 58 with good crystallinity on the upper side.

Next, an antiferromagnetic layer 58 made of a PtMn film having a thickness of 20 nm is formed by, eg, sputtering.

Next, the ferromagnetic layer 60 made of a CoFe film having a thickness of 3 nm is formed by, eg, sputtering.

Next, the nonmagnetic layer 62 made of a Ru film having a thickness of 0.9 nm is formed by, eg, sputtering.

Next, the ferromagnetic layer 64 made of a CoFe film having a thickness of 3 nm is formed by, eg, sputtering. The ferromagnetic layer 60, the nonmagnetic layer 62, and the ferromagnetic layer 64 constitute a fixed layer 66.

[0109] Next, tunnel insulation made of lnm-thick alumina (AIO) is formed by, for example, sputtering.

X

A film 68 is formed.

Next, a ferromagnetic layer 70 made of a CoFe film having a thickness of 2 nm is formed by, eg, sputtering. Next, a ferromagnetic layer 72 made of a NiFe film having a thickness of 4 nm is formed by, eg, sputtering. The ferromagnetic layer 70 and the ferromagnetic layer 72 constitute a free layer 74.

Next, a Ru (ruthenium) film 76 having a thickness of 1 nm is formed by, eg, sputtering. As will be described later, the Ru film 76 functions as an etching stopper when the conductive layer 78 is patterned to form the upper electrode. In addition, as will be described later, when the Ru film 76 is heat-treated while applying a magnetic field to align the spin direction in the fixed layer 66, the atoms in the upper electrode 78 and the atoms in the free layer 74 are interdiffused. It also functions as a diffusion preventive film (nore film) that prevents this.

Next, the conductive layer 78 made of a Ta film with a thickness of 30 nm is formed by, eg, sputtering.

The conductive layer 78 becomes an upper electrode. Further, as will be described later, the conductive layer 78 functions as a hard mask (cap layer) when the free layer 74 and the like are patterned.

[0114] Next, a photoresist film 86 is formed on the entire surface by, eg, spin coating.

[0115] Next, the photoresist film 86 is patterned using a photolithography technique (see FIG. 3B). When exposing the photoresist film 86, for example, it is exposed using an electron beam.

Next, as shown in FIG. 4 (a), the conductive layer 78 is formed by the RIE (Reactive Ion Etching) method using the photoresist film 86 as a mask and the Ru film 76 as an etching stopper. Etch. As the etching apparatus, for example, an inductively coupled plasma (ICP) etching apparatus is used. The inductively coupled plasma etching apparatus is a plasma etching apparatus using a high-density plasma generated by accelerating electrons by generating an induction electric field in plasma by a high frequency induction magnetic field generated by an antenna. The etching conditions are as follows, for example. Halogen gas is used as the etching gas. More specifically, a mixed gas of halogen gas and Ar gas is used. For example, C1 gas is used as the halogen-based gas. C1 gas flow

2 2 The amount is, for example, 20 sccm. The flow rate of Ar gas is, for example, 17 sccm. The pressure in the chamber when performing etching is, for example, 0.7 Pa. The power applied to the upper electrode of the etching apparatus is 800 W, for example. The power applied to the lower electrode of the etching apparatus is 60 W, for example. The etching time is 20 seconds, for example. For example, the conductive layer 78 is patterned by etching for about 15 seconds. One bar etch is performed. The over-etching is performed in order to pattern the conductive layer 78 uniformly in the wafer surface.

[0117] Since the Ru film 76 functions as an etching stopper when the conductive layer 78 is etched, the conductive layer 78 can be uniformly patterned in the wafer surface. Further, since the selection ratio of the conductive layer 78 to the Ru film 78 is sufficiently high, even the Ru film 76 is not etched when the conductive layer 78 is etched. Therefore, the Ru film 76 can prevent the free layer 74 from being damaged when the conductive layer 78 is etched.

[0118] Although the case where a Ta film is used as the material of the conductive layer 78 has been described as an example here, the material of the conductive layer 78 is not limited to the Ta film. For example, a Ti film or a TiN film may be used as the material for the conductive layer 78. Even when a Ti film or a TiN film is used as the material of the conductive layer 78, the conductive layer 78 can be etched with a high selectivity with respect to the Ru film 76.

[0119] The halogen-based gas is not limited to the C1 gas. For example, halogen-based gas

2

As gas, CF gas or the like may be used. Even when CF gas is used,

4 4

The conductive layer 78 can be etched at a high selectivity.

[0120] As described above, the material of the conductive layer 78, the etching gas, and the like may be appropriately set so that the conductive layer 78 can be etched with a high selection ratio with respect to the Ru film 76.

Thus, the upper electrode made of the conductive layer 78 is formed. As will be described later, the upper electrode 78 also functions as a hard mask when the free layer 74 and the like are etched.

Next, as shown in FIG. 4 (b), the upper electrode 78 is used as a node mask, the conductive layer 54 is used as an eztin dust flange, a Ru film 76, a free layer 74, a tunnel insulating film 68, a fixed layer 66, The ferromagnetic layer 58 and the NiFe film 56 are etched. The etching conditions are as follows. As the etching gas, for example, a mixed gas of CO gas and NH gas is used. CO gas flow rate

Three

For example, 5 sccm. The flow rate of NH gas is 40 sccm, for example. Etching rate

Three

Is, for example, lOnmZ.

Next, as shown in FIG. 5 (a), the conductive layer 54 is patterned using a photolithography technique. Thereby, a lower electrode made of the conductive layer 54 is formed.

Next, as shown in FIG. 5B, an interlayer insulating film 80 made of a silicon oxide film is formed by a low temperature plasma CVD method. The film formation temperature is, for example, 300 ° C or lower. Next, the surface of the interlayer insulating film 80 is planarized by CMP.

Next, as shown in FIG. 6A, a contact hole 82 reaching the upper electrode 78 is formed by using a photolithography technique.

Next, the direction of spin in the fixed layer 66 is aligned by performing heat treatment while applying a magnetic field. The heat treatment temperature is, for example, 260 ° C. The strength of the magnetic field is 2T, for example. Since the Ru film 76 is formed between the free layer 74 and the upper electrode 78, even if such a heat treatment is performed, the atoms in the free layer 74 and the atoms in the upper electrode 78 are interdiffused. The

It can be prevented by the Ru film 76.

Next, as shown in FIG. 6B, a conductive layer 84 made of, eg, aluminum is formed on the entire surface by, eg, sputtering.

[0129] Next, the conductive layer 84 is patterned using a photolithography technique. Thus, a bit line made of the conductive layer 84 is formed. The bit line 84 is electrically connected to the upper electrode of the magnetoresistive element.

Thus, the magnetic memory device according to the present embodiment is manufactured.

According to the present embodiment, the main feature is that the Ru film 76 is formed between the free layer 74 and the conductive layer 78.

[0132] According to the present embodiment, the Ru film 76 is formed between the free layer 74 and the upper electrode 78. Therefore, when the upper electrode is formed by etching the conductive layer 78, the Ru film 76 is etched. Functions as a stock. Therefore, according to the present embodiment, it is possible to prevent the free layer 74 from being damaged when the conductive layer 78 is etched. In addition, since the conductive layer 78 is etched using the Ru film 76 as an etch stopper, the patterning of the conductive layer 78 can be performed uniformly in the wafer surface. Therefore, according to the present embodiment, the magnetic resistance element can be formed with a high yield.

Further, according to the present embodiment, since the free layer 74 and the like are patterned using the upper electrode 78 as a mask, it is not necessary to form the photoresist film 86 very thickly. Since it is not necessary to form the photoresist film 86 very thickly, the photoresist film 86 can be finely patterned. Therefore, according to the present embodiment, the magnetoresistive element can be formed finely. Further, according to the present embodiment, as will be described later, since the Ru film 76 functions as an etching stopper, it is not necessary to detect the etching end point using a plasma spectroscopic analyzer or the like. Therefore, according to the present embodiment, the conductive layer 78 can be patterned easily and reliably.

Further, according to the present embodiment, the Ru film 76 formed between the free layer 74 and the upper electrode 78 is formed by the constituent atoms of the free layer 76 in the heat treatment when aligning the spin direction in the fixed layer 66. It also functions as a diffusion prevention film (barrier film) that prevents mutual diffusion between the upper electrode 78 and the constituent atoms of the upper electrode 78. Therefore, according to the present embodiment, the Ru film 76 can prevent the atoms constituting the upper electrode 78 and the atoms constituting the free layer 76 from interdiffusion.

As described above, according to the present embodiment, a magnetic memory device having a fine magnetoresistive element can be manufactured at a high yield.

[0137] (Evaluation result)

Next, evaluation results of the magnetic memory device and the manufacturing method thereof according to the present embodiment will be described with reference to FIGS.

7 and 8 are graphs showing concentration profiles in the depth direction obtained by Auger Electron Spectroscopy (AES). The AES method is a method for identifying and quantifying elements on the surface of a sample by irradiating a solid surface with an electron beam and measuring the electron energy distribution emitted by the Auge transition. When performing the analysis, the analysis was performed while sputtering the surface of the laminated film. The horizontal axis indicates the sputtering time, and the vertical axis indicates the atomic concentration.

FIG. 7 shows the case of the present embodiment, that is, the case where the Ta film is formed on the NiFe film via the Ru film. The thickness of the NiFe film was 10 nm. The film thickness of the Ru film was lnm. The thickness of the Ta film was 30 nm. The dotted line in Fig. 7 shows the case of analysis by AES method without heat treatment. The solid line in Fig. 7 shows the case of analysis by AES method after heat treatment at 330 ° C for 30 minutes.

[0140] FIG. 8 shows the case of the comparative example, that is, the case where the Ta film without forming the Ru film is directly formed on the NiFe film. The thickness of the NiFe film was 10 nm. The thickness of the Ta film was 30 nm. The dotted line in Fig. 8 shows the case of analysis by AES method without heat treatment. The solid line in Fig. 8 shows the case of analysis by AES after heat treatment at 330 ° C for 30 minutes.

[0141] As shown in FIG. 8, in the case of the comparative example, that is, when the Ta film is directly formed on the NiFe film without forming the Ru film, the laminated film is obtained by performing heat treatment. The Ta concentration in the vicinity of the surface becomes lower. In the case of the comparative example, the Ni concentration in the vicinity of the surface of the laminated film is increased by performing the heat treatment. From these, it can be seen that in the case of the comparative example, the atoms constituting the NiFe film and the atoms constituting the Ta film are mutually diffused by heat treatment.

On the other hand, as can be seen from FIG. 7, in the case of this embodiment, when a Ta film is formed on a NiFe film via a Ru film, even if heat treatment is performed, it is in the vicinity of the surface of the laminated film. The Ta concentration has hardly changed. In the present embodiment, even when heat treatment is performed, the Ni concentration in the vicinity of the surface of the laminated film is hardly changed. From these facts, it can be seen that in the case of the present embodiment, the atoms constituting the NiFe film and the atoms constituting the Ta film can be prevented from interdiffusion.

From these facts, according to the present embodiment, the atoms constituting the free layer 76 and the atoms constituting the upper electrode 78 are mutually diffused in the heat treatment for aligning the spin direction in the fixed layer 66. It can be seen that the Ru film 76 can prevent this.

[0144] FIG. 9 is a graph showing a magnetization curve (Magnetization Curve) measured by a sample vibration magnetometer (VSM). In Fig. 9, the horizontal axis indicates the external magnetic field, and the vertical axis indicates the magnetic field. In FIG. 9, the thin solid line shows the case of the comparative example, that is, the case where the Ta film is formed directly on the NiFe film without forming the Ru film. In FIG. 9, the thick solid line shows the case of the present embodiment, that is, the case where the Ta film is formed on the NiFe film via the Ru film.

As shown in FIG. 9, in this embodiment, the saturation magnetization is increased by about 15% compared to the comparative example.

[0146] From this, it can be seen that according to the present embodiment, a magnetoresistive element having good characteristics can be formed. In the present embodiment, such good characteristics can be obtained because the atoms constituting the free layer 76 and the atoms constituting the free layer 76 are subjected to heat treatment when aligning the spin direction in the fixed layer 66. This is because the Ru film 76 can prevent the atoms constituting the upper electrode 78 from interdiffusion.

[Modified Embodiment]

The present invention is not limited to the above embodiment, and various modifications can be made.

For example, in the above embodiment, the case where the antiferromagnetic layer 58, the fixed layer 66, the tunnel insulating film 68, and the free layer 74 are sequentially stacked on the lower electrode 54 has been described as an example. The laminated structure of 52 is not limited to this. For example, the free layer 74, the tunnel insulating film 68, the fixed layer 66, and the antiferromagnetic layer 58 may be sequentially stacked on the lower electrode 54. In this case, a Ru film 76 may be formed between the antiferromagnetic layer 58 and the upper electrode 78.

In the above embodiment, the case where the upper electrode 78 remains on the Ru film 76 has been described as an example. However, after patterning the free layer 74 and the like, the upper electrode 78 is polished and removed. May be. In this case, the bit line 84 also serves as the upper electrode of the magnetoresistive element 52. In this case, it is preferable that the Ru film 76 be formed thick so that when the upper electrode 78 is removed by polishing, even the Ru film 76 is removed and the free layer 74 is not damaged.

[0150] In the above-described embodiment, the Ru film 76 and the mixed gas of CO gas and NH gas are used.

Three

Although the case where the free layer 74 and the like are etched has been described as an example, the etching gas used for etching the Ru film 76 and the free layer 74 and the like is not limited thereto. For example, use methanol gas as the etching gas. Even when methanol gas is used, it is possible to etch the Ru film 76, the free layer 74, and the like with a high selectivity.

[0151] In the above embodiment, the case where a CoFe film or a NiFe film is used as the material of the free layer 74 has been described as an example. However, the material of the free layer 74 is not limited to the CoFe film or the NiFe film. . Any magnetic material that can be etched at a high selectivity with respect to the upper electrode 78 can be used as the material of the free layer 74 as appropriate. For example, a magnetic material containing at least one of Co (cobalt), Fe (iron), and Ni (nickel) can be used as the material of the free layer 74.

[0152] In the above embodiment, the case where a CoFe film or the like is used as the material of the fixed layer 66 has been described as an example. However, the material of the fixed layer 66 is not limited to the CoFe film or the like. Any magnetic material that can be etched at a high selectivity with respect to the upper electrode 78 is used as the material of the fixed layer 66. It can be used as appropriate. For example, a magnetic material containing at least one of Co, Fe, and Ni can be used as the material of the fixed layer 66.

[0153] In the above embodiment, the case where a PtMn film is used as the material of the antiferromagnetic layer 58 has been described as an example. However, the material of the antiferromagnetic layer 58 is not limited to the PtMn film. Any antiferromagnetic material that can be etched at a high selectivity with respect to the upper electrode 78 can be appropriately used as the material of the antiferromagnetic layer 58. For example, an IrMn (Ir: iridium, Mn: manganese) film may be used as the material of the antiferromagnetic layer 58.

[0154] In the above embodiment, the case where an alumina film is used as the material of the tunnel insulating film 68 has been described as an example. However, the material of the tunnel insulating film 68 is not limited to the alumina film. Any insulating material that can be etched with a high selectivity with respect to the upper electrode 78 can be used as the material of the tunnel insulating film 68 as appropriate. For example, MgO (Mg: Magnesium), HfO (Hf: Hafnium), HfAlO (A1: Aluminum), TiO, etc. can be tunneled.

2 X X

It can also be used as a material for the edge film 68.

Industrial applicability

The magnetic memory device and the manufacturing method thereof according to the present invention are useful for manufacturing a magnetic memory device having fine magnetoresistive elements with a high yield.

Claims

The scope of the claims

[1] a first magnetic layer formed on a substrate; a tunnel insulating film formed on the first magnetic layer; a second magnetic layer formed on the tunnel insulating film; A magnetic memory device having a magnetoresistive element having an electrode formed on a second magnetic layer,

A magnetic memory device further comprising a ruthenium film formed between the second magnetic layer and the electrode.

[2] In the magnetic memory device according to claim 1,

The electrode comprises tantalum, titanium or titanium nitride

A magnetic memory device.

[3] In the magnetic memory device according to claim 1 or 2,

The second magnetic layer includes cobalt, iron, or nickel

A magnetic memory device.

[4] In the magnetic memory device according to claim 1 or 2,

The second magnetic layer includes a CoFe film or a NiFe film

A magnetic memory device.

[5] forming a first magnetic layer on the substrate;

Forming a tunnel insulating film on the first magnetic layer;

Forming a second magnetic layer on the tunnel insulating film;

Forming a ruthenium film on the second magnetic layer;

Forming a conductive layer on the ruthenium film;

Forming a photoresist mask on the conductive layer;

Etching the conductive layer by using the photoresist mask and using the ruthenium film as an etching stopper to form an electrode made of the conductive layer; and using the electrode as a mask, at least the ruthenium film and the second layer Etching the magnetic layer of

A method of manufacturing a magnetic memory device, comprising:

[6] In the method of manufacturing a magnetic memory device according to claim 5,

The conductive layer includes tantalum, titanium, or titanium nitride. A method of manufacturing a magnetic memory device.

[7] In the method of manufacturing a magnetic memory device according to claim 5 or 6,

The second magnetic layer includes cobalt, iron, and nickel

A method of manufacturing a magnetic memory device.

[8] In the method of manufacturing a magnetic memory device according to claim 5 or 6,

The second magnetic layer includes a CoFe film or a NiFe film

A method of manufacturing a magnetic memory device.

[9] In the method of manufacturing a magnetic memory device according to any one of claims 5 to 8,

In the step of etching the conductive layer, the conductive layer is etched using a halogen-based gas.

A method of manufacturing a magnetic memory device.

[10] In the method of manufacturing a magnetic memory device according to any one of claims 5 to 9,

In the step of etching the ruthenium film and the second magnetic layer, CO gas and NH gas are etched.

Etching the ruthenium film and the second magnetic layer using a mixed gas with 3 s. A method of manufacturing a magnetic memory device, comprising:

[11] In the method of manufacturing a magnetic memory device according to any one of claims 5 to 9,

In the step of etching the ruthenium film and the second magnetic layer, the ruthenium film and the second magnetic layer are etched using methanol gas.

A method of manufacturing a magnetic memory device.

[12] In the method of manufacturing a magnetic memory device according to any one of claims 5 to 11,

After the step of etching the ruthenium film and the second magnetic layer, the first magnetic layer is subjected to a heat treatment while applying a magnetic field to the first magnetic layer or the second magnetic layer. Alternatively, the method of manufacturing a magnetic memory device, further comprising the step of aligning spin directions in the second magnetic layer.