JP5277629B2 - Memory element having magnetoresistive effect, method for manufacturing the same, and nonvolatile magnetic memory device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a memory device having magnetoresistive effect, which enables micro fabrication of a laminated structure having a recording layer. <P>SOLUTION: The memory device has magnetoresistive effect and includes: the laminated structure 50 containing the recording layer 53; a first wiring 41 electrically connected to the lower portion of the laminated structure 50; and a second wiring 62 connected to the upper portion of the laminated structure 50 via a junction portion 62. The method for manufacturing the memory device comprises steps of: (A) forming an unpatterned laminated structure 50A on the first wiring 41; (B) forming a resist layer 71 having an opening portion 73 at a place for forming a junction portion 62 on the laminated structure 50A; (C) forming a junction portion 62 in the opening portion 73 provided in the resist layer 71 and removing the resist layer 71; and then (D) patterning a recording layer 53A constituting at least the laminated structure 50A by using the junction portion 62 as a mask. <P>COPYRIGHT: (C)2009,JPO&amp;INPIT

Description

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

  With the rapid spread of information communication equipment, especially small personal devices such as portable terminals, various semiconductor devices such as memory elements and logic elements constituting them are becoming more integrated, faster, lower power, etc. There is a demand for higher performance. In particular, nonvolatile memories are considered essential in the ubiquitous era. Even when power is consumed or troubled, or the server and the network are disconnected due to some kind of failure, important information can be stored and protected by the nonvolatile memory. Also, recent portable devices are designed to keep unnecessary circuit blocks in standby state and reduce power consumption as much as possible, but if non-volatile memory that can serve as both high-speed work memory and large-capacity storage memory can be realized , Power consumption and memory waste can be eliminated. In addition, an “instant-on” function that can be instantly started when the power is turned on is possible if a high-speed and large-capacity nonvolatile memory can be realized.

Examples of the nonvolatile memory include a flash memory using a semiconductor material and a ferroelectric nonvolatile semiconductor memory (FERAM, Ferroelectric Random Access Memory) using a ferroelectric material. However, the flash memory has a drawback that the writing speed is on the order of microseconds and the writing speed is slow. On the other hand, in FERAM, the number of rewritable times is 10 ¹² to 10 ¹⁴ , and the number of rewritable FERAMs is not sufficient to replace SRAM or DRAM with FERAM, and fine processing of the ferroelectric layer is difficult. The problem is pointed out.

  As a non-volatile memory that does not have these drawbacks, a non-volatile magnetic memory element called MRAM (Magnetic Random Access Memory) has attracted attention. Among these MRAMs, the MRAM using the TMR (Tunnel Magnetoresistance) effect has been attracting attention due to the recent improvement in characteristics of the TMR material (for example, see Non-Patent Document 1). The TMR type MRAM has a simple structure, is easy to scale, and performs recording by rotating a magnetic moment, so that the number of rewritable times is large. Furthermore, the access time is expected to be very high, and it is said that it can already operate at 100 MHz (for example, see Non-Patent Document 2).

  A schematic partial cross-sectional view of a TMR type MRAM (hereinafter simply referred to as MRAM) is shown in FIG. This MRAM is composed of a tunnel magnetoresistive effect element TMJ connected to a selection transistor TR made of a MOS type FET.

  The tunnel magnetoresistive element TMJ has a laminated structure of a first ferromagnetic layer 151, a tunnel insulating film 152, and a second ferromagnetic layer. More specifically, the first ferromagnetic layer 151 has, for example, a two-layer configuration of an antiferromagnetic layer 151A and a ferromagnetic layer (also referred to as a fixed layer or a fixed magnetization layer 151B) from the bottom. , Due to the exchange interaction acting between these two layers, it has a strong unidirectional magnetic anisotropy. The second ferromagnetic layer whose magnetization direction rotates relatively easily is also called a free layer or a recording layer. In the following description, the second ferromagnetic layer may be referred to as a recording layer 153. The tunnel insulating film 152 plays a role of cutting the magnetic coupling between the recording layer 153 and the magnetization fixed layer 151B and flowing a tunnel current. A bit line BL (second wiring) for connecting the MRAM and the MRAM is formed on the interlayer insulating layer 26. The cap layer 161 provided between the bit line BL and the recording layer 153 prevents interdiffusion between atoms constituting the bit line BL and atoms constituting the recording layer 153, reduces contact resistance, and the recording layer 153. It is responsible for preventing oxidation. A connection portion 162 is provided between the cap layer 161 and the bit line BL. In the figure, reference numeral 141 indicates a first wiring connected to the lower surface of the antiferromagnetic material layer 151A.

  Further, a write word line RWL is arranged below the tunnel magnetoresistive effect element TMJ via the second lower insulating layer 24. Note that the direction in which the write word line RWL extends (first direction) and the direction in which the bit line BL (second wiring) extends (second direction) are usually orthogonal.

  On the other hand, the selection transistor TR is formed in the portion of the silicon semiconductor substrate 10 surrounded by the element isolation region 11 and covered with the first lower insulating layer 21. One source / drain region 14B is connected to the first wiring 141 of the tunnel magnetoresistive effect element TMJ through a connection hole 22 made of a tungsten plug, a landing pad portion 23, and a connection hole 25 made of a tungsten plug. ing. The other source / drain region 14 A is connected to the sense line 16 through a tungsten plug 15. In the figure, reference numeral 12 indicates a gate electrode (functioning as a so-called word line), and reference numeral 13 indicates a gate insulating film. In the MRAM array, the MRAM is arranged at the intersection (overlapping area) of the lattice composed of the bit line BL and the write word line RWL.

  In writing data to the MRAM having such a configuration, a positive or negative current is supplied to the bit line BL, and a constant current is supplied to the write word line RWL. As a result, a resultant magnetic field is generated. By changing the magnetization direction of the recording layer 153, “1” or “0” is recorded in the recording layer 153.

  On the other hand, data reading is performed by turning on the selection transistor TR, passing a current through the bit line BL, and detecting a change in tunnel current due to the magnetoresistive effect by the sense line 16. When the magnetization directions of the recording layer 153 and the magnetization fixed layer 151B are the same, the resistance is low (this state is set to “0”, for example). When the magnetization directions of the recording layer 153 and the magnetization fixed layer 151B are antiparallel, the resistance is high. (This state is set to “1”, for example).

  Thus, in order to stably hold recorded information in the MRAM, the recording layer 153 for recording information needs to have a certain coercive force. On the other hand, in order to rewrite recorded information, a certain amount of current must be passed through the bit line BL. However, as the MRAM is miniaturized, the bit line BL becomes thinner, and it is becoming difficult to pass a sufficient current. Therefore, a spin-injection magnetoresistive effect element using magnetization reversal by spin injection has attracted attention as a configuration capable of reversing magnetization with a smaller current (see, for example, Japanese Patent Laid-Open No. 2003-17782). Here, magnetization reversal by spin injection is a phenomenon in which magnetization reversal occurs in another magnetic material when electrons that have been spin-polarized through the magnetic material are injected into the other magnetic material. .

FIG. 9A shows a conceptual diagram of the spin injection type magnetoresistive effect element. In this spin injection type magnetoresistive element, a laminated film having a GMR (Giant Magnetoresistance) effect or a magnetoresistive laminated film made of a laminated film having a TMR effect is sandwiched between two wirings 41 and 42. Has a structure. That is, a recording layer (also referred to as a magnetization reversal layer or a free layer) 53 having a function of recording information and a magnetization reference layer (also referred to as a fixed layer) 51 having a fixed magnetization direction and functioning as a spin filter are provided. The magnetic film 52 has a laminated structure, and current flows perpendicularly to the film surface (see FIG. 9A). The size of the recording layer 53 is shown in a schematic plan view in FIG. 9B, and depends on the type and film thickness of the magnetic material constituting the recording layer 53, but promotes the formation of a single magnetic domain, and In order to reduce the critical current I _c of the spin transfer magnetization reversal, it is approximately 200 nm or less. The recording layer 53 has a plurality of magnetization directions of two or more due to appropriate magnetic anisotropy (for example, a first direction and a second direction which are two directions indicated by horizontal arrows in FIG. 9A). And each magnetization direction corresponds to recorded information. FIG. 9B shows an example in which shape magnetic anisotropy is imparted by making the planar shape of the recording layer 53 into an elliptical shape. In other words, the recording layer 53 has an easy magnetization axis parallel to the first direction and the second direction, and a hard magnetization axis orthogonal to the easy magnetization axis, and the recording layer 53 along the easy magnetization axis. Is longer than the length of the recording layer 53 along the hard axis of magnetization.

FIG. 11 shows the relationship between the memory cell size and the write current. Here, the right vertical axis in FIG. 11 indicates the memory cell size (F ² ), the left vertical axis indicates the write current, and the horizontal axis indicates the short side size of the MTJ (Magnetic Tunneling Junction) element. As apparent from FIG. 11, the spin injection magnetization switching type has a smaller write current as the element size is reduced. In addition, the write current is about the same cell size as the embedded DRAM, and the write current is as low as 100 μA. On the other hand, in the conventional MRAM, the write current greatly increases as the element size is reduced. In addition, when the cell size is about the same as that of a 6-transistor type SRAM (6TSRAM), the write current is about 1 mA.

  In such a spin injection type magnetoresistive effect element, the device structure can be simplified as compared with the MRAM. Further, by using magnetization reversal by spin injection, there is an advantage that the write current does not increase as described above even if the device is miniaturized as compared with the MRAM that performs magnetization reversal by an external magnetic field.

  With reference to FIGS. 12A to 12C and FIGS. 13A and 13B, an outline of a method for obtaining the patterned laminated structure 50 in the spin injection magnetoresistive element will be described below. explain.

[Step-10]
First, an unpatterned laminated structure 50A, a cap layer 61A, and a connection portion 62A are sequentially formed on the first wiring 41A based on a sputtering method. The laminated structure 50A has a structure in which a magnetization reference layer, a nonmagnetic film, and a recording layer 53A are laminated from the bottom (see FIG. 12A).

[Step-20]
After that, an oxide film 301 functioning as a hard mask is formed on the connection portion 62A, and then a resist layer 302 is formed on the oxide film 301 based on a photolithography technique (see FIG. 12B). The resist layer 302 is made of a positive resist material. Therefore, the shape of the resist layer 302 is usually a shape that spreads downward as shown in FIG. The width of the top surface of the resist layer 302 is defined as W ₀ ′.

[Step-30]
Next, after etching the oxide film 301 using the resist layer 302 as an etching mask, the resist layer 302 is removed. Thus, the state shown in FIG. 12C can be obtained.

[Step-40]
Thereafter, using the patterned oxide film 301 as an etching mask, the connecting portion 62A is etched by the RIE method to obtain a patterned connecting portion 62 (see FIG. 13A). The planar shape of the patterned connection portion 62 is, for example, an ellipse. After that, the oxide film 301 is removed (see FIG. 13B).

[Step-50]
Next, the cap layer 61A and the laminated structure 50A are etched using the patterned connection portion 62 (the width of the top surface is W ₁ ′) as an etching mask. Thus, a patterned laminated structure can be obtained.

JP2003-17782A Wang et al., "Feasibility of Ultra-Dense Spin-Tunneling Random Access Memory", IEEE Transactions on Magnetics, Vol.33, November 1997, pp.4498-4512 R. Scheuerlein et al., "A 10ns Read and Write Non-Volatile Memory Array Using a Magnetic Tunnel Junction and FET Switch in each Cell", 2000 IEEE International Solid-State Circuits Conference Digest of Technical Papers, Feb. 2000, pp. 128-129

By the way, as the spin injection magnetoresistive element is miniaturized, the length along the hard axis of the recording layer 53 is becoming 100 nm or less. Usually, when the connection part 62 patterned in the above [Step-40] is obtained, the side wall (side surface) of the connection part 62 becomes a shape (forward taper shape) that spreads downward. In forming the recording layer 53, a relatively large dimensional conversion difference is likely to occur (that is, W ₀ ′ <W ₁ ′), and the size of the recording layer 53 is likely to vary. Further, in [Step-20], a dot-like resist layer 302 made of a positive resist material is formed. However, since the size of the resist layer 302 is small, the resist layer 302 is easily inclined and has high dimensional accuracy. Therefore, it is difficult to form the resist layer 302. In order to prevent the inclination of the resist layer 302, the thickness of the resist layer 302 may be reduced. However, in this case, the resist layer 302 disappears during the etching of the oxide film 301.

  Accordingly, an object of the present invention is to provide a method of manufacturing a memory element having a magnetoresistive effect that enables microfabrication of a laminated structure having a recording layer, and a magnetoresistive effect obtained by a method of manufacturing a memory element having such a magnetoresistive effect. And a nonvolatile magnetic memory device including the memory element having the magnetoresistive effect.

In order to achieve the above object, a method for manufacturing a memory element having a magnetoresistive effect according to the first and second aspects of the present invention includes:
(A) a laminated structure having a recording layer;
(B) a first wiring electrically connected to the lower part of the laminated structure; and
(C) a second wiring connected to the upper part of the laminated structure via a connection part;
A method for manufacturing a memory element having magnetoresistive effect.

And the manufacturing method of the memory element which has a magnetoresistive effect concerning the 1st mode of the present invention,
(A) After forming an unpatterned laminated structure on the first wiring,
(B) On the laminated structure, a resist layer in which an opening is provided in a portion where a connection portion is to be formed is formed.
(C) After forming the connection portion in the opening provided in the resist layer, the resist layer is removed, and then
(D) patterning at least the recording layer constituting the laminated structure using the connection portion as a mask;
It comprises the process.

A method for manufacturing a memory element having a magnetoresistance effect according to the second aspect of the present invention includes:
(A) After forming an unpatterned laminated structure on the first wiring,
(B) forming an opening forming layer on the laminated structure;
(C) By forming a resist layer having an opening at a portion where a connection portion is to be formed on the opening forming layer, and then selectively removing the opening forming layer using the resist layer as a mask. Then, after providing the opening where the connection portion is to be formed in the opening forming layer, the resist layer is removed,
(D) After forming the connecting portion in the opening provided in the opening forming layer, removing the opening forming layer,
(E) patterning at least the recording layer constituting the laminated structure using the connection portion as a mask;
It comprises the process.

  In the method for manufacturing a memory element having a magnetoresistive effect according to the first aspect or the second aspect of the present invention, at least the recording layer constituting the laminated structure is patterned using the connection portion as a mask. In the patterning of the laminated structure using as a mask, only the recording layer may be patterned or other layers constituting the laminated structure may be patterned in addition to the recording layer. The first wiring may be patterned at the time of forming an unpatterned stacked structure, or may be patterned after patterning at least the recording layer constituting the stacked structure using the connection portion as a mask. .

In order to achieve the above object, a memory element having a magnetoresistive effect of the present invention includes:
(A) a laminated structure having a recording layer;
(B) a first wiring electrically connected to the lower part of the laminated structure; and
(C) a second wiring connected to the upper part of the laminated structure via a connection part;
A memory element having a magnetoresistive effect, comprising:
When the area of the lower end surface of the connecting portion in contact with the laminate structure S _D, the area of the upper surface of the connection portion in contact with the second wiring and the S _U,
S _D / S _U <1
It is characterized by satisfying.

In order to achieve the above object, the nonvolatile magnetic memory device of the present invention is
(A) a laminated structure having a recording layer;
(B) a first wiring electrically connected to the lower part of the laminated structure; and
(C) a second wiring connected to the upper part of the laminated structure via a connection part;
A magnetoresistive memory device comprising:
A non-volatile magnetic memory device having a selection transistor made of a field effect transistor below a first wiring,
When the area of the lower end surface of the connecting portion in contact with the laminate structure S _D, the area of the upper surface of the connection portion in contact with the second wiring and the S _U,
S _D / S _U <1
It is characterized by satisfying.

A method of manufacturing a memory element having a magnetoresistive effect according to the first aspect of the present invention (hereinafter, sometimes referred to as “manufacturing method according to the first aspect of the present invention”), or a second aspect of the present invention In the method for manufacturing a memory element having a magnetoresistive effect according to the embodiment (hereinafter, sometimes referred to as “manufacturing method according to the second embodiment of the present invention”), the lower end surface (bottom surface) of the connection portion in contact with the laminated structure area of S _D) of, when the upper end surface of the connecting portion in contact with the second wiring area (the top surface) was S _U,
S _D / S _U <1
Preferably,
0.7 ≦ S _D / S _U ≦ 0.9
It is desirable to satisfy Similarly, in the memory element having the magnetoresistive effect of the present invention and the nonvolatile magnetic memory device of the present invention, preferably,
0.7 ≦ S _D / S _U ≦ 0.9
It is desirable to satisfy

  In the manufacturing method according to the first aspect of the present invention including the above preferred embodiment, a sidewall is provided on the side wall of the opening provided in the resist layer between the step (B) and the step (C). By forming, it can be set as the form which reduces the magnitude | size of an opening part, and in the manufacturing method which concerns on the 2nd aspect of this invention containing said preferable form, said process (C) and During the step (D), the size of the opening can be reduced by forming the side wall on the side wall of the opening provided in the opening forming layer, thereby further reducing the size. It is possible to provide a simplified recording layer.

  Furthermore, in the manufacturing method according to the first aspect of the present invention including the preferred embodiment described above, the formation of the connection portion in the opening provided in the resist layer in the step (C) is performed by plating. It is preferable to be based on a method or a physical vapor deposition method (PVD method). Further, in the manufacturing method according to the second aspect of the present invention including the preferred embodiment described above, the formation of the connection portion in the opening provided in the opening forming layer in the step (D) It is preferable to use a plating method or a PVD method. Examples of the plating method include an electrolytic plating method, an electroless plating method, and a combination of the electroless plating method and the electrolytic plating method. When using the plating method, the same kind of material as the plating film is generally used as the seed film, but a different material may be used. For example, Au or Pt may be formed as a plating film on a seed film made of Cu or Ti, or Cu or Ni may be formed as a plating film on a seed film made of Ru or Rh. Further, as the PVD method, various vacuum deposition methods such as an electron beam heating method, a resistance heating method, and a flash deposition method; a plasma deposition method; a bipolar sputtering method, a direct current sputtering method, a direct current magnetron sputtering method, a high frequency sputtering method, and a magnetron sputtering method Various sputtering methods such as ion beam sputtering and bias sputtering; DC (Direct Current) method, RF method, multi-cathode method, activation reaction method, HCD (Hollow Cathode Discharge) method, field evaporation method, high-frequency ion plating And various ion plating methods such as reactive ion plating method; IVD method (ion vapor deposition method).

  Furthermore, in the manufacturing method according to the first aspect of the present invention including the preferred embodiment described above, in the step (D), a dry etching method (specifically, for example, reactive ion etching ( (RIE) method) or ion milling method (ion beam etching method), and in the manufacturing method according to the second aspect of the present invention including the preferred embodiment described above, In the step (E), patterning can be performed by a dry etching method (specifically, for example, an RIE method) or an ion milling method.

  Further, in the manufacturing method according to the second aspect of the present invention including the preferred embodiment described above, the opening forming layer can be made of a silicon-based oxide film.

  Furthermore, the manufacturing method according to the first aspect or the second aspect of the present invention including the preferred embodiment described above, the memory element having the magnetoresistive effect according to the present invention including the preferable embodiment described above, or the nonvolatile magnetic field In the memory device, the memory element having a magnetoresistive effect can be configured by a spin injection type magnetoresistive effect element using magnetization reversal by spin injection, but is not limited to this. For example, the TMR effect It can also be comprised from the tunnel magnetoresistive effect element using this.

  In the nonvolatile magnetic memory device of the present invention including the preferable configuration described above, the extending direction of the second wiring (for example, bit line) is parallel to the extending direction of the gate electrode constituting the field effect transistor. However, the present invention is not limited to this, and the projected image in the extending direction of the second wiring may be orthogonal to the projected image in the extending direction of the gate electrode constituting the field effect transistor. it can. A selection transistor made of a field effect transistor is formed below the first wiring. Specifically, the selection transistor is covered with an interlayer insulating layer, and the first transistor is covered on the interlayer insulating layer. A wiring is formed, and one source / drain region of the selection transistor is connected to the first wiring through a connection hole (or a connection hole and a landing pad portion or a lower layer wiring) provided in the interlayer insulating layer. It can be set as a structure. The interlayer insulating layer may cover the lower insulating layer and the first wiring, surround the stacked structure and the connection portion, and the second wiring may be formed on the interlayer insulating layer. In some cases, a selection transistor is not required.

The manufacturing method according to the first aspect or the second aspect of the present invention including the preferred embodiment described above, the memory element or the nonvolatile magnetic memory device having the magnetoresistive effect of the present invention including the preferable embodiment described above ( Hereinafter, these may be collectively referred to simply as “the present invention”), and the first wiring and the second wiring (for example, function as a so-called bit line) may be Cu, Au, It may have a single layer structure such as Pt, or may have a laminated structure of an underlayer made of Cr, Ti, etc., and a Cu layer, Au layer, Pt layer, etc. formed thereon, Can be composed of a single layer of W, Ru, Ta or the like or a laminated structure of Cu, Cr, Ti or the like. As a material constituting the connection portion that also functions as a hard mask, a noble metal such as Ru, Rh, Au, Pt, or Ag, a metal such as Cr, Ti, W, Cu, Ni, or Zn, or any one of these is included. Mention may be made of alloys. As the material constituting the interlayer insulating layer, SiO _2, NSG (non-doped silicate glass), BPSG (boron phosphorus silicate glass), PSG, BSG, AsSG, SbSG, SiO X system such as SOG (spin on glass) Material (material constituting silicon-based oxide film), SiN, SiON, SiOF, low dielectric constant SiO _x- based material (for example, polyaryl ether, cycloperfluorocarbon polymer and benzocyclobutene, cyclic fluororesin, polytetrafluoroethylene, Examples thereof include fluorinated aryl ether, fluorinated polyimide, amorphous carbon, and organic SOG). Moreover, as a material which comprises a sidewall, an organic material, specifically, TSAR-100 by Tokyo Ohka Kogyo Co., Ltd. can be illustrated. By configuring the side wall from such a material, the side wall can be formed only on the resist layer, and on the connection portion exposed at the bottom of the opening provided in the resist layer or the opening forming layer. No side wall is formed. Alternatively, examples of the material constituting the sidewall include the material constituting the interlayer insulating layer described above. In addition, examples of the material that forms the opening forming layer include the same materials as the material that forms the interlayer insulating layer described above. However, it is not essential to have an insulating property, and the material may be made of a conductive material. In short, the opening forming layer may be made of a material that can reliably remove the opening forming layer without adversely affecting other layers. When the sidewall is formed by the etch back method, it is desirable that there is a high etching selectivity between the material constituting the sidewall and the material constituting the opening forming layer. In other words, when the material constituting the sidewall is etched back in order to form the sidewall, it is desirable that the opening forming layer is formed of a material that is difficult to be etched.

  As the planar shape of the recording layer or laminated structure, an ellipse, an ellipse (a figure in which two semicircles and two line segments are combined), a shape surrounded by a parabola or a hyperbola, a quadratic function or Shapes composed of figures that can be expressed by functions of cubic or higher, regular polygons (rectangles, regular pentagons or more, polygons with rounded vertices, regular pentagons with rounded vertices or more (Including regular polygons), flat circles (shapes that are crushed from one direction), combinations of ellipses and line segments, combinations of parabola and line segments, hyperbolas A combination with a line segment, broadly, a combination of a quadratic function and a linear function, or a combination of a function of cubic or higher and a linear function can be included. Alternatively, it can be a curved shape.

  Here, in the spin-injection magnetoresistive element, a magnetization reference layer (also referred to as a pinned layer), a nonmagnetic film, and a recording layer for storing information (also referred to as a magnetization reversal layer or a free layer) It can be set as the structure in which the laminated structure which has a TMR effect or a GMR effect is comprised. A laminated structure having a TMR effect is constituted by the magnetization reference layer, the nonmagnetic film, and the recording layer. A tunnel insulating film is provided between the magnetization reference layer made of a magnetic material and the recording layer made of a magnetic material. A non-magnetic film functioning as a structure is sandwiched. As a state of electrical connection between the magnetization reference layer and the first wiring (or second wiring), the first wiring (or second wiring) is directly connected to the magnetization reference layer. Alternatively, the first wiring (or the second wiring) may be connected to the magnetization reference layer through the antiferromagnetic material layer. When the magnetization reference layer is connected to the first wiring, the magnetization is generated from the first wiring through the magnetization reference layer, and when the magnetization reference layer is connected to the second wiring, the magnetization from the second wiring. By injecting a polarized spin current into the recording layer through the reference layer, the magnetization direction in the recording layer is changed to the first direction (direction parallel to the easy axis of magnetization) or the second direction (first direction). In the opposite direction), information is written to the recording layer. The magnetization reference layer can be configured to have a stacked ferrimagnetic structure (a stacked structure having antiferromagnetic coupling), or the magnetization reference layer can be configured to have a magnetostatic coupling structure. The laminated ferri structure is, for example, a three-layer structure of magnetic material layer / ruthenium (Ru) layer / magnetic material layer (specifically, for example, a three-layer structure of CoFe / Ru / CoFe, CoFeB / Ru / CoFeB 3 Layer structure), and the interlayer exchange coupling between the two magnetic material layers is antiferromagnetic or ferromagnetic depending on the thickness of the ruthenium layer. A structure in which the interlayer exchange coupling between the two magnetic material layers becomes ferromagnetic is called a laminated ferro structure. In addition, a structure in which antiferromagnetic coupling is obtained by the leakage magnetic field from the end face of the magnetic material layer in the two magnetic material layers is called a magnetostatic coupling structure. Examples of the material constituting the antiferromagnetic material layer include iron-manganese alloys, nickel-manganese alloys, platinum-manganese alloys, iridium-manganese alloys, rhodium-manganese alloys, cobalt oxides, and nickel oxides. A base film made of Ta, Cr, Ru, Ti or the like is formed between the first wiring (or the second wiring) and the antiferromagnetic material layer in order to improve the crystallinity of the antiferromagnetic material layer. May be.

As a material constituting the recording layer (magnetization switching layer) and the magnetization reference layer in the spin injection type magnetoresistive effect element, ferromagnetic materials such as nickel (Ni), iron (Fe), cobalt (Co), and the like of these ferromagnetic materials Alloys (for example, Co-Fe, Co-Fe-Ni, Ni-Fe, etc.), alloys in which these alloys are mixed with nonmagnetic elements (for example, tantalum, boron, chromium, platinum, silicon, carbon, nitrogen, etc.) For example, a group of intermetallic compounds called Heusler (such as Co—Fe—B), an oxide containing one or more of Co, Fe, and Ni (eg, ferrite: Fe—MnO), a half-metallic ferromagnetic material. _{alloy: NiMnSb, Co 2 MnGe, Co} 2 MnSi, Co 2 CrAl etc.), oxides (e.g., (La, Sr) be exemplified _{MnO 3, CrO 2, Fe 3} O 4 , etc.) It can be. The crystallinity of the recording layer and the magnetization reference layer is essentially arbitrary, and may be polycrystalline, single crystal, or amorphous. Furthermore, various magnetic semiconductors can be used, and may be soft magnetic (soft film) or hard magnetic (hard film).

Magnesium oxide (MgO), magnesium nitride, aluminum oxide (AlO _x ), aluminum nitride are used as materials constituting the non-magnetic film constituting the multilayer structure having the TMR effect in the spin injection type magnetoresistive effect element. Insulating materials such as (AlN), silicon oxide, silicon nitride, TiO ₂ or Cr ₂ O ₃ , Ge, NiO, CdO _x , HfO ₂ , Ta ₂ O ₅ , BN, and ZnS can be given. On the other hand, examples of the material constituting the non-magnetic film constituting the laminated structure having the GMR effect include conductive materials such as Cu, Ru, Cr, Au, Ag, Pt, Ta, and alloys thereof. If it has high conductivity (resistivity is several hundred μΩ · cm or less), any non-metallic material may be used, but a material that does not easily cause an interface reaction with the recording layer or the magnetization reference layer should be appropriately selected. Is desirable.

  These layers are formed by, for example, a chemical vapor deposition method represented by a physical vapor deposition method (PVD method) ALD (Atomic Layer Deposition) method exemplified by a sputtering method, an ion beam deposition method, and a vacuum deposition method ( (CVD method).

  The nonmagnetic film can be obtained, for example, by oxidizing or nitriding a metal film formed by a sputtering method. More specifically, when magnesium oxide (MgO) is used as an insulating material constituting the nonmagnetic film, for example, a method of oxidizing magnesium formed by a sputtering method in the atmosphere or a sputtering method is used. A method of oxidizing plasma magnesium, a method of oxidizing magnesium formed by sputtering with IPC plasma, a method of naturally oxidizing magnesium formed by sputtering in oxygen, and a method of magnesium formed by sputtering A method of oxidizing with oxygen radicals, a method of irradiating ultraviolet rays when magnesium formed by sputtering is naturally oxidized in oxygen, a method of forming a film of magnesium by reactive sputtering, and a magnesium oxide (MgO) Illustrates the method of forming a film by sputtering It is possible.

  On the other hand, when the memory element having the magnetoresistive effect is a tunnel magnetoresistive effect element using the TMR effect, the stacked structure includes the first ferromagnetic layer, the tunnel insulating film, and the recording layer (second ferromagnetic material). Layer or free layer). Here, more specifically, the first ferromagnetic layer has, for example, a two-layer configuration of an antiferromagnetic layer and a ferromagnetic layer (also referred to as a fixed layer or a fixed magnetization layer). Preferably, this can have a strong unidirectional magnetic anisotropy due to the exchange interaction acting between these two layers. Note that the magnetization fixed layer is in contact with the tunnel insulating film. Alternatively, the magnetization fixed layer more specifically includes, for example, a multilayer structure (for example, ferromagnetic material layer / metal layer / ferromagnetic material layer) having a synthetic antiferromagnetic coupling (SAF). You can also Synthetic antiferromagnetic coupling is reported, for example, in S. S. Parkin et al., Physical Review Letters, 7 May, pp 2304-2307 (1990). In the recording layer, the magnetization direction rotates relatively easily. The tunnel insulating film breaks the magnetic coupling between the recording layer and the magnetization fixed layer and plays a role for flowing a tunnel current.

  The first ferromagnetic layer (pinned layer, magnetization fixed layer) and recording layer (second ferromagnetic layer, free layer) in the tunnel magnetoresistive element are, for example, transition metal magnetic elements, specifically, Ferromagnetic material composed of nickel (Ni), iron (Fe) or cobalt (Co), or an alloy thereof (for example, Co-Fe, Co-Fe-Ni, Ni-Fe, etc.) It can be comprised from a magnetic body. In addition, a so-called half-metallic ferromagnetic material or an amorphous ferromagnetic material such as CoFe-B can be used. Examples of the material constituting the antiferromagnetic material layer include iron-manganese alloys, nickel-manganese alloys, platinum-manganese alloys, iridium-manganese alloys, rhodium-manganese alloys, cobalt oxides, and nickel oxides. . These layers can be formed by, for example, a PVD method exemplified by a sputtering method, an ion beam deposition method, and a vacuum evaporation method.

Aluminum oxide (AlO _x ), aluminum nitride (AlN), magnesium oxide (MgO), magnesium nitride, silicon oxide, and silicon nitride are used as the insulating material constituting the tunnel insulating film in the tunnel magnetoresistive effect element. it can be mentioned, further, there can be mentioned _{Ge, NiO, CdO X, HfO} 2, Ta 2 O 5, BN, and ZnS. The tunnel insulating film can be obtained, for example, by oxidizing or nitriding a metal film formed by a sputtering method. More specifically, when aluminum oxide (AlO _x ) is used as an insulating material constituting the tunnel insulating film, for example, a method of oxidizing aluminum formed by a sputtering method in the atmosphere or a sputtering method is used. A method of oxidizing aluminum formed by sputtering, a method of oxidizing aluminum formed by sputtering with IPC plasma, a method of naturally oxidizing aluminum formed by sputtering in oxygen, and an aluminum formed by sputtering. A method of oxidizing with oxygen radicals, a method of irradiating ultraviolet rays when aluminum formed by sputtering is naturally oxidized in oxygen, a method of depositing aluminum by reactive sputtering, and a method of sputtering aluminum oxide Explain how to deposit It can be. Alternatively, the tunnel insulating film can be formed by an ALD method.

  In the MRAM (tunnel magnetoresistive element), the lower insulating layer has a structure in which a first lower insulating layer and a second lower insulating layer are stacked, and the write word line is the first lower insulating layer. The second lower insulating layer is formed on the insulating layer, and has a configuration covering the write word line and the first lower insulating layer.

The selection transistor can be constituted by, for example, a well-known MIS type FET or MOS type FET. The connection hole for electrically connecting the first wiring and the selection transistor is made of polysilicon doped with impurities, tungsten, Ti, Pt, Pd, Cu, TiW, TiNW, WSi ₂ , MoSi ₂ or the like. It can be composed of a melting point metal or a metal silicide, and can be formed based on a CVD method or a PVD method exemplified by a sputtering method. Examples of the material constituting the lower insulating layer include silicon oxide (SiO ₂ ), silicon nitride (SiN), SiON, SOG, NSG, BPSG, PSG, BSG, or LTO. In addition, the lower layer wiring and the write word line in the tunnel magnetoresistive effect element are made of, for example, aluminum, an aluminum alloy such as Al-Cu, or copper (Cu), and are formed by, for example, a PVD method exemplified by a sputtering method. can do.

  In the method of manufacturing a memory element having a magnetoresistive effect according to the first aspect or the second aspect of the present invention, after forming the connection portion in the opening provided in the resist layer or the opening formation layer, Using the connection portion as a mask, at least the recording layer constituting the laminated structure is patterned. That is, since a minute opening (hole shape) may be formed to form the connection portion, the resist layer does not tilt as in the conventional technique. And since the shape of the opening provided in the resist layer or the opening formation layer becomes a shape narrowed downward, the shape of the obtained connection part is also narrowed downward (reverse taper shape) Furthermore, the shape of the recording layer obtained when patterning at least the recording layer constituting the laminated structure using the connection portion as a mask is a shape (forward taper shape) spreading downward. As a result, a difference in dimensional conversion hardly occurs in the size of the finally obtained recording layer, and variations in the size of the recording layer hardly occur. In addition, the number of processes can be reduced. In addition, since it is not necessary to form a dot-like resist layer in order to obtain a connection portion, a fine connection portion can be formed with high dimensional accuracy. Since the shape and dimensions of the connecting portion are defined only by controlling the pattern of the resist layer, there is almost no difference in dimensional conversion compared to the conventional technique, and the variation can be made extremely small. In addition, since it is not necessary to form a connection portion that also functions as a hard mask by an etching method, not only the number of processes can be reduced, but also variations due to etching and damage to the stacked structure can be reduced. Since the reverse tapered shape of the connecting portion can be easily formed, it is possible to make the dimensional conversion difference negative, that is, to make it smaller than the size of the resist layer.

  Hereinafter, the present invention will be described based on examples with reference to the drawings.

Example 1 relates to a method of manufacturing a memory element having a magnetoresistive effect according to the first aspect of the present invention, a memory element having a magnetoresistive effect of the present invention, and a nonvolatile magnetic memory device of the present invention. FIG. 1 shows a schematic partial cross-sectional view of a nonvolatile magnetic memory device of Example 1 or Example 2 to Example 4 described later. Here, a memory element having a magnetoresistive effect (hereinafter referred to as a magnetoresistive effect element 30). Specifically, in the embodiment, a spin injection type magnetoresistive effect element using magnetization reversal by spin injection is used. Is)
(A) a laminated structure 50 having a recording layer 53;
(B) a first wiring 41 electrically connected to the lower portion of the laminated structure 50, and
(C) a second wiring 42 (functioning as a bit line) connected to the upper portion of the laminated structure 50 via a connecting portion 62;
It has. Further, in the nonvolatile magnetic memory device of Example 1 or Examples 2 to 4 described later, a selection transistor TR made of a field effect transistor is further provided below the first wiring 41. Have.

In Example 1 or Examples 2 to 4 to be described later, the area of the lower end surface (bottom surface) of the connection portion 62 that contacts the laminated structure 50 is in contact with S _D and the second wiring 42. when the area of the upper surface of the connecting portion 62 (the top surface) was S _U,
S _D / S _U <1
Satisfied. Specifically, for example,
S _D / S _U = 0.8
It is.

  In the schematic partial cross-sectional view shown in FIG. 1, the cross section of the nonvolatile magnetic memory device is shown in the upper “A” region and the lower “B” region of the alternate long and short dash line because of the drawing. The viewing direction is 90 degrees different. That is, the area “A” is a cross section of the nonvolatile magnetic memory device viewed from a direction parallel to the hard axis, and the area “B” is a cross section of the nonvolatile magnetic memory device parallel to the easy axis. Looking from the direction. Therefore, in FIG. 1, the projection image in the extending direction of the second wiring (bit line in the first embodiment) 42 and the projection image in the extending direction of the gate electrode 12 constituting the field effect transistor are orthogonal to each other. However, in reality, they are parallel.

  Here, the recording layer 53 constituting the stacked structure 50 has an easy magnetization axis and a hard magnetization axis orthogonal to the easy magnetization axis. In the first embodiment, the easy axis of magnetization is parallel to the second wiring 42. Further, as described above, the connection portion 62 is provided between the upper portion of the multilayer structure 50 and the second wiring 42. Here, the connecting portion 62 is made of ruthenium (Ru). A cap layer 61 made of a Ta layer having a thickness of about 5 nm is formed between the laminated structure 50 and the connection portion 62 by a sputtering method. The cap layer 61 is responsible for preventing interdiffusion between the atoms constituting the wiring and connecting portion 62 and the atoms constituting the recording layer 53, reducing the contact resistance, and preventing the recording layer 53 from being oxidized. In addition, examples of the cap layer include a Ru layer, a Pt layer, a MgO layer, and a laminated structure of a Ru film / Ta film.

  Furthermore, as described above, the selection transistor TR made of a field effect transistor is provided below the first wiring 41, and the extending direction of the second wiring (bit line) 42 is the field effect transistor. Is parallel to the extending direction of the gate electrode 12 constituting the. Specifically, the selection transistor TR is formed in a portion of the silicon semiconductor substrate 10 surrounded by the element isolation region 11 and covered with the lower insulating layers 21 and 24. One source / drain region 14B is connected to the first wiring 41 through a connection hole 22 made of a tungsten plug. The other source / drain region 14 A is connected to the sense line 16 through a tungsten plug 15. In the figure, reference numeral 12 indicates a gate electrode (functioning as a so-called word line), and reference numeral 13 indicates a gate insulating film.

  As shown in the conceptual diagram of FIG. 9A, the laminated structure 50 has the following configuration and structure, and is formed by a sputtering method. In the magnetization fixed layer, the magnetization direction is pinned by exchange coupling with Pt—Mn of the antiferromagnetic material layer constituting the upper bottom layer. In the recording layer 53, the magnetization direction is changed to be parallel or antiparallel to the magnetization fixed depending on the direction in which the current flows.

Specifically, the spin-injection magnetoresistive effect element according to the first embodiment includes two magnetoresistive effect multilayer films having a GMR (Giant Magnetoresistance) effect or a multilayer effect having a TMR effect. It has a structure sandwiched between two wirings 41, 42. That is, a recording layer (also referred to as a magnetization reversal layer or a free layer) 53 having a function of recording information and a magnetization reference layer (also referred to as a fixed layer) 51 having a fixed magnetization direction and functioning as a spin filter are provided. The magnetic film 52 has a laminated structure, and current flows perpendicularly to the film surface (see FIG. 9A). The size of the recording layer 53 is shown in a schematic plan view in FIG. 9B, and depends on the type and film thickness of the magnetic material constituting the recording layer 53, but promotes the formation of a single magnetic domain, and In order to reduce the critical current I _c of the spin transfer magnetization reversal, it is approximately 200 nm or less. The recording layer 53 has a plurality of magnetization directions of two or more due to appropriate magnetic anisotropy (for example, a first direction and a second direction which are two directions indicated by horizontal arrows in FIG. 9A). And each magnetization direction corresponds to recorded information. FIG. 9B shows an example in which shape magnetic anisotropy is imparted by making the planar shape of the recording layer 53 into an elliptical shape. That is, the recording layer 53 has an easy magnetization axis parallel to the first direction and the second direction and a hard magnetization axis, and the length of the recording layer 53 along the easy magnetization axis is difficult to magnetize. It is longer than the length of the recording layer 53 along the axis.

  The magnetization reference layer 51 is typically fixed in the magnetization direction by exchange coupling with the antiferromagnetic material layer 54 (see FIG. 9C). There is also known a double spin filter structure in which the magnetization reference layers 51A and 51B are arranged above and below the recording layer 53 via non-magnetic films 52A and 52B to improve the efficiency of spin injection magnetization reversal ( (See FIG. 9D). Here, reference numerals 54A and 54B are antiferromagnetic layers. In the example shown in FIGS. 9A, 9C, and 9D, the recording layer 53 and the magnetization reference layer 51 (in the case where the magnetization reference layer is the two layers 51A and 51B, either one of them) Layer) may have a laminated ferri structure. The nonmagnetic films 52, 52A and 52B are made of a metal material or an insulating material. In the structure shown in FIG. 9A or 9C, in order to suppress the leakage magnetic field from the magnetization reference layer 51 to the recording layer 53, that is, the magnetization reference layer 51 and the recording layer 53 are static. In order to prevent magnetic coupling, a structure in which the magnetization reference layer 51 is sufficiently larger than the recording layer 53 is also employed. In any case, a nonvolatile magnetic memory element (spin injection type magnetoresistive effect element) to which spin injection magnetization reversal is applied has a two-terminal spin transfer element structure in which a magnetoresistive layered film is sandwiched between wirings.

[Laminated structure 50]
Recording layer 53
Co-Fe-B layer with a thickness of about 3 nm Non-magnetic film (tunnel insulating film) 52
MgO film having a thickness of 1.0 nm Magnetized reference layer (multilayer film having SAF) 51 (shown as one layer in the drawing)
Upper layer: Co—Fe—B layer Middle layer: Ru layer Lower layer: Co—Fe layer,

The first wiring 41 has a two-layer structure of an upper layer made of an antiferromagnetic material layer made of a Pt—Mn alloy having a thickness of 20 nm and a lower layer made of a Ta layer having a thickness of 10 nm. In the drawing, the first wiring 41 is displayed in one layer. The second wiring 42 is made of, for example, Ta, Ti, or Al—Cu. The interlayer insulating layer 26 surrounding the laminated structure 50 is made of SiN or SiO ₂ .

  Hereinafter, with reference to FIGS. 2A to 2C and FIGS. 3A to 3D, which are schematic partial end views of the lower insulating layer 24 and the like, the magnetoresistive effect of Example 1 will be described. A method for manufacturing a memory device having the above will be described. 2 to 7, the selection transistor TR is not shown, and the connection hole 22 provided in the lower insulating layer 24 is also omitted.

[Step-100]
First, based on a well-known method, an element isolation region 11 is formed in a silicon semiconductor substrate 10, and a gate oxide film 13, a gate electrode 12, and source / drain regions are formed in a portion of the silicon semiconductor substrate 10 surrounded by the element isolation region 11. A selection transistor TR composed of 14A and 14B is formed. Next, a first lower insulating layer 21 is formed, a tungsten plug 15 is formed in the portion of the first lower insulating layer 21 above the source / drain region 14A, and the sense line 16 is further formed on the first lower insulating layer 21. Form. Thereafter, a second lower insulating layer 24 is formed on the entire surface, and a connection hole 22 made of a tungsten plug is formed in the lower insulating layers 21 and 24 above the source / drain regions 14B. Thus, the selection transistor TR covered with the lower insulating layers 21 and 24 can be obtained.

[Step-110]
After that, an unpatterned stacked structure is formed over the first wiring (see FIG. 2A). Specifically, the first wiring 41A, the laminated structure 50A, and the cap layer 61A having a non-patterned two-layer structure are formed on the entire surface by sputtering and continuous film formation in vacuum. Since these layers are not patterned, “A” is added to the end of the reference number.

[First wiring 41A having a two-layer structure]
Process gas: Argon = 100 sccm
Deposition atmosphere pressure: 0.6 Pa
DC power: 200W
[Magnetization reference layer 51A]
Lower layer process gas: Argon = 50 sccm
Deposition atmosphere pressure: 0.3 Pa
DC power: 100W
Middle process gas: Argon = 50 sccm
Deposition atmosphere pressure: 0.3 Pa
DC power: 50W
Upper layer process gas: Argon = 50 sccm
Deposition atmosphere pressure: 0.3 Pa
DC power: 100W
[Non-magnetic film 52A]
Process gas: Argon = 100 sccm
Deposition atmosphere pressure: 1.0 Pa
RF power: 500W
[Recording layer 53A]
Process gas: Argon = 50 sccm
Deposition atmosphere pressure: 0.3 Pa
DC power: 200W
[Cap layer 61A]
Process gas: Argon = 100 sccm
Deposition atmosphere pressure: 0.6 Pa
DC power: 200W

[Step-120]
Thereafter, a resist layer 71 in which an opening 73 is provided in a portion where the connection portion 62 is to be formed is formed on the stacked structure 50A based on a well-known photolithography technique. The resist layer 71 is made of a positive resist material, and the side surface of the opening 73 provided in the resist layer 71 is inclined as shown in FIG. 2B, and the size of the upper end of the opening 73 ( Width: W ₀ ) is larger than the size of the lower end portion of the opening 73. That is, the opening 73 has a shape narrowed downward. The thickness of the resist layer 71 is set to 0.2 μm, for example. The planar shape of the opening 73 is an ellipse.

[Step-130]
Next, the connection part 62 is formed in the opening 73 provided in the resist layer 71. Specifically, based on the electrolytic plating method, ruthenium (Ru) is formed on the laminated structure 50A exposed to the bottom of the opening 73 (more specifically, on the cap layer 61A in the first embodiment). The connection part 62 which consists of is formed (refer (C) of FIG. 2). Thereafter, the resist layer 71 is removed based on the ashing process (see FIG. 3A). The connection portion 62 thus obtained has a shape (reverse taper shape) in which the side wall (side surface) is narrowed downward. That is, the value of S _D / S _{U is} a value less than 1 as described above. Further, the planar shape of the connecting portion 62 is an ellipse.

[Step-140]
Thereafter, at least the recording layer 53 constituting the laminated structure 50 is patterned using the connection portion 62 as a mask. Specifically, based on the reactive ion etching (RIE) method which is a kind of dry etching method, in Example 1, the stacked structure 50A including the cap layer 61A and the recording layer 53A is etched. Thus, the recording layer 53 and the cap layer 61 having an elliptical planar shape can be obtained. Here, the side walls (side surfaces) of the recording layer 53 and the cap layer 61 obtained usually have a shape (forward taper shape) that expands downward. Thus, the structure shown in FIG. 3B can be obtained. Note that the cap layer 61A and the stacked structure 50A can be patterned based on an ion milling method (ion beam etching method) instead of patterning by the RIE method. In some cases, etching is performed up to the recording layer 53 in the laminated structure 50, and at this time, the nonmagnetic film (tunnel insulating film) 52A and the magnetization reference layer 51A may not be etched. When the width of the recording layer 53 is W ₁ , W ₀ > W ₁ . That is, the dimensional conversion difference is negative.

[Step-150]
Next, a resist layer (not shown) that covers the first wiring 41A to be left is formed, the first wiring 41A is etched, and the resist layer is removed to obtain the patterned first wiring 41. (See FIG. 3C). If the nonmagnetic film 52A and the magnetization reference layer 51A are not etched in [Step-140], the nonmagnetic film 52A and the magnetization reference layer 51A are etched in [Step-150]. Just do it.

[Step-160]
Next, after an interlayer insulating layer 26 is formed on the entire surface by a CVD method, the interlayer insulating layer 26 is planarized by a chemical mechanical polishing method (CMP method) to expose the connection portion 62 ((( D)).

[Step-170]
Thereafter, the second wiring 42 in contact with the connection portion 62 is formed on the interlayer insulating layer 26 by a well-known method, whereby the nonvolatile magnetic memory device shown in FIG. 1 can be obtained.

  In Example 1, after forming the connecting portion 62 in the opening 73 provided in the resist layer 71 in [Step-130], in [Step-140], at least using the connecting portion 62 as a mask. The recording layer 53 constituting the laminated structure 50 is patterned. That is, since a minute opening 73 (hole shape) may be formed in order to form the connection portion 62, the resist layer does not tilt as in the conventional technique. Since the shape of the opening 73 provided in the resist layer 71 becomes a shape narrowed downward, the shape of the obtained connection part 62 is also a shape narrowed downward (reverse taper shape). It becomes. Further, the shape of the recording layer 53 obtained by patterning at least the recording layer 53A constituting the laminated structure with the connection portion 62 as a mask is a shape (forward taper shape) spreading downward. As a result, a difference in size conversion hardly occurs in the size of the finally obtained recording layer 53, and the size of the recording layer 53 does not easily vary. Further, since it is not necessary to form a dot-like resist layer in order to obtain the connection portion 62, a fine connection portion can be formed with high dimensional accuracy. In addition, since the shape and dimensions of the connecting portion 62 are defined only by controlling the pattern of the resist layer 71, there are almost no dimensional conversion differences and variations can be made extremely small as compared with the conventional technique. Furthermore, since it is not necessary to form the connection portion 62 that also functions as a hard mask by an etching method, not only the number of processes can be reduced, but also variations due to etching and damage to the laminated structure 50 can be reduced.

Specifically, for example, the width of the upper end W ₀ of the opening 73 provided in the resist layer 71 is 100 nm, and the width of the lower end of the opening 73 is 80 nm. In the case of patterning the recording layer 53A, the connection portion 62 having an inversely tapered shape is formed, and the dimension of the lower end surface of the connection portion 62 as a mask is 80 nm as a reference. Therefore, in patterning the recording layer 53A, 10 nm Even when the forward tapered shape is obtained (processing conversion difference 10 nm), the dimension W ₁ of the recording layer 53 is 90 nm, and the width of the upper end portion of the opening 73 provided in the resist layer 71 is 100 nm. The conversion difference is -10 nm, and a dimensional conversion difference minus can be realized.

  The second embodiment is a modification of the method for manufacturing the memory element having the magnetoresistive effect of the first embodiment. Hereinafter, with reference to FIGS. 4A and 4B which are schematic partial end views of the lower insulating layer 24 and the like, a method for manufacturing a memory element having a magnetoresistive effect of Example 2 will be described.

[Step-200]
First, the structure shown in FIG. 2B can be obtained by executing the same steps as [Step-100] to [Step-120] of the first embodiment.

[Step-210]
Thereafter, a side wall 74 is formed on the side wall of the opening 73 provided in the resist layer 71 to reduce the size of the opening 73. Specifically, a sidewall forming layer 74A made of an organic material (specifically, TSAR-100 manufactured by Tokyo Ohka Kogyo Co., Ltd.) is formed on the entire surface including the inside of the opening 73 based on a coating method. The sidewall forming layer 74A is not formed on the laminated structure 50A exposed to the bottom of the opening 73 (more specifically, on the cap layer 61A in the first embodiment), but the top of the resist layer 71 is not formed. It is formed only on the face and side walls. Thus, as shown in FIG. 4A, the side wall 74 is formed on the side wall of the opening 73.

[Step-220]
Next, in the same manner as in [Step-130] of Example 1, after forming the connection portion 62 in the opening 73 provided in the resist layer 71 (see FIG. 4B), the resist layer 71 and By removing the side wall 74 and the side wall forming layer 74A, a structure substantially similar to that shown in FIG. 3A can be obtained.

[Step-230]
Thereafter, by performing the same steps as [Step-140] to [Step-170] of Example 1, the nonvolatile magnetic memory device of Example 2 can be obtained.

  In Example 2, the sidewall 74 is formed on the side wall of the opening 73 provided in the resist layer 71 in [Step-210], so that an extremely small opening that is hardly resolvable by lithography. An extremely fine connecting portion 62 based on 73 (hole shape) can be obtained.

  Example 3 relates to a method of manufacturing a memory element having a magnetoresistive effect according to the second aspect of the present invention, a memory element having a magnetoresistive effect of the present invention, and a nonvolatile magnetic memory device of the present invention. The configuration and structure of the magnetoresistive effect element 30 and the nonvolatile magnetic memory device in the third embodiment can be the same as the configuration and structure of the magnetoresistive effect element 30 and the nonvolatile magnetic memory device described in the first embodiment. Detailed description will be omitted.

  Hereinafter, with reference to FIGS. 5A and 5B and FIGS. 6A and 6B which are schematic partial end views of the lower insulating layer 24 and the like, the magnetoresistive effect of Example 3 will be described. A method for manufacturing a memory device having the above will be described.

[Step-300]
First, the selection transistor TR, the lower insulating layers 21 and 24, and the like are formed in the same manner as in [Step-100] of the first embodiment, and then the first step is performed in the same manner as in [Step-110] of the first embodiment. An unpatterned laminated structure 50A and a cap layer 61A are formed on one wiring 41A.

[Step-310]
Thereafter, an opening forming layer 80 is formed on the laminated structure 50A (more specifically, on the cap layer 61A in the third embodiment). Specifically, an opening forming layer 80 made of a silicon-based oxide film such as SiO ₂ is formed on the entire surface based on the CVD method.

[Step-320]
Next, a resist layer 81 in which an opening 82 is provided in a portion where the connection portion 62 is to be formed is formed on the opening forming layer 80 based on a well-known photolithography technique. The resist layer 81 is made of a positive resist material, and the side surface of the opening 82 provided in the resist layer 81 is inclined as shown in FIG. 5 (A). It is larger than the size of the lower end portion of 82. That is, the opening 82 has a shape narrowed downward. The planar shape of the opening 82 is an ellipse.

[Step-330]
Thereafter, the opening formation layer 80 is selectively removed based on, for example, the RIE method using the resist layer 81 as a mask, thereby providing the opening 83 for forming the connection portion 62 in the opening formation layer 80. Then, the resist layer 81 is removed based on the ashing process (see FIG. 5B and FIG. 6A). The side wall of the opening 83 provided in the opening forming layer 80 is inclined as shown in FIG. 6A, and the size of the upper end of the opening 83 is the size of the lower end of the opening 83. Bigger than that. That is, the opening 83 has a shape narrowed downward. The planar shape of the opening 83 is an ellipse.

[Step-340]
Next, after the connection portion 62 is formed in the opening 83 provided in the opening forming layer 80, the opening forming layer 80 is removed. Specifically, on the laminated structure 50A exposed to the bottom of the opening 73 based on the electroless plating method and the electrolytic plating method (more specifically, even on the cap layer 61A in Example 3). After the ruthenium layer is formed on the opening forming layer 80 including the ruthenium layer, the ruthenium layer on the opening forming layer 80 is removed by a CMP method. Thus, the structure shown in FIG. 6B can be obtained. Thereafter, by removing the opening forming layer 80 based on a wet etching method, a structure similar to that shown in FIG. 3A can be obtained.

[Step-350]
Thereafter, in the same manner as in [Step-140] in Example 1, the recording layer 53 constituting at least the laminated structure 50 is formed using the connection portion 62 having a shape narrowed downward (reverse taper shape) as a mask. Pattern. Specifically, based on the RIE method, in Example 3, the laminated structure 50A including the cap layer 61A and the recording layer 53A is etched, whereby the recording layer 53 and the cap layer having an elliptical planar shape are etched. 61 can be obtained. Here, the side walls (side surfaces) of the recording layer 53 and the cap layer 61 obtained usually have a shape (forward taper shape) that expands downward. Thus, the structure shown in FIG. 3B can be obtained. Note that the cap layer 61A and the stacked structure 50A can be patterned based on an ion milling method (ion beam etching method) instead of patterning by the RIE method. In some cases, etching is performed up to the recording layer 53 in the laminated structure 50, and at this time, the nonmagnetic film (tunnel insulating film) 52A and the magnetization reference layer 51A may not be etched.

[Step-360]
Next, by performing [Step-150], [Step-160], and [Step-170] of Example 1, the nonvolatile magnetic memory device of Example 3 can be obtained.

  In Example 3, after the connection portion 62 is formed in the opening 83 provided in the opening formation layer 80 in [Step-340], the connection portion 62 is used as a mask in [Step-350]. Then, at least the recording layer 53 constituting the laminated structure 50 is patterned. That is, since a minute opening 82 (hole shape) may be formed to form the connection portion 62, the resist layer does not tilt as in the conventional technique. Since the shape of the opening 83 provided in the opening forming layer 80 is narrowed downward, the shape of the obtained connecting portion 62 is also narrowed downward (reverse taper shape). ) Further, the shape of the recording layer 53 obtained by patterning at least the recording layer 53A constituting the laminated structure with the connection portion 62 as a mask is a shape (forward taper shape) spreading downward. As a result, a difference in size conversion hardly occurs in the size of the finally obtained recording layer 53, and the size of the recording layer 53 does not easily vary. Further, since it is not necessary to form a dot-like resist layer in order to obtain the connection portion 62, a fine connection portion can be formed with high dimensional accuracy. Further, since the shape and size of the connecting portion 62 are defined only by controlling the pattern of the resist layer 81, there is almost no dimensional conversion difference and variation can be made extremely small as compared with the conventional technique. Furthermore, since it is not necessary to form the connection portion 62 that also functions as a hard mask by an etching method, not only the number of steps can be reduced, but also variations due to etching and damage to the laminated structure can be reduced.

  The fourth embodiment is a modification of the method of manufacturing the memory element having the magnetoresistive effect of the third embodiment. Hereinafter, with reference to FIGS. 7A and 7B which are schematic partial end views of the lower insulating layer 24 and the like, a method for manufacturing a memory element having a magnetoresistive effect of Example 4 will be described.

[Step-400]
First, by performing the same steps as [Step-300] to [Step-330] in Example 3, the structure shown in FIG. 6A can be obtained.

[Step-410]
Thereafter, the side wall 84 is formed on the side wall of the opening 83 provided in the opening forming layer 80, thereby reducing the size of the opening 83. Specifically, a sidewall forming layer made of SiN or polysilicon is formed on the entire surface including the inside of the opening 83 based on the CVD method, and then etched back, whereby the sidewall on the opening forming layer 80 is formed. By removing the formation layer and leaving the sidewall formation layer only on the side wall of the opening 83, the sidewall 84 can be obtained. In this way, the structure shown in FIG. 7A can be obtained.

[Step-420]
Next, in the same manner as in [Step-340] in Example 3, the connection portion 62 is formed in the opening portion 83 provided in the opening portion formation layer 80 (see FIG. 7B), and then the opening portion. By removing the formation layer 80 and the sidewall 84, a structure substantially similar to that shown in FIG. 3A can be obtained.

[Step-430]
Thereafter, by performing the same steps as [Step-350] and [Step-360] of Embodiment 3, the nonvolatile magnetic memory device of Embodiment 4 can be obtained.

  In the fourth embodiment, the sidewall 84 is formed on the side wall of the opening 83 provided in the opening forming layer 80 in [Step-410]. An extremely fine connection 62 based on the opening 82 (hole shape) can be obtained.

  As mentioned above, although this invention was demonstrated based on the preferable Example, this invention is not limited to these Examples. Various laminated structures described in the examples, materials used, and the like are examples, and can be changed as appropriate. In each of the embodiments, the spin-injection magnetoresistive element having a structure in which the recording layer is positioned in the uppermost layer of the multilayer structure has been described. A spin-injection magnetoresistive effect element having the following can also be used. Further, the magnetization reference layer 51, the nonmagnetic film 52, and the recording layer 53 constituting the stacked structure are not made to have the same shape and size, but the magnetization reference layer 51 and the nonmagnetic film 52 are formed on the first wiring 41. You may extend to. The projected image in the extending direction of the second wiring (bit line) 42 may be orthogonal to the projected image in the extending direction of the gate electrode 12 constituting the selection transistor TR. In the embodiment, the planar shape of the recording layer is an ellipse, but it may be a shape disclosed in Japanese Patent Application Laid-Open No. 2005-353788 (Japanese Patent Application No. 2004-172122) instead.

Further, in addition to the spin-injection magnetoresistive effect element described in the embodiment, for example, as shown in FIG. 8, a nonvolatile magnetic memory device provided with a tunnel magnetoresistive effect element using the TMR effect is provided. You can also. The nonvolatile magnetic memory device having the tunnel magnetoresistive effect element of the present invention shown in FIG. 8 and the conventional nonvolatile magnetic memory device having the tunnel magnetoresistive effect element shown in FIG. The shape of the body 150 (from the bottom, the first ferromagnetic layer 151 composed of the antiferromagnetic layer 151A and the magnetization fixed layer 151B, the tunnel insulating film 152, and the recording layer 153) and the connecting portion 162 are different. Yes. That is, in the conventional tunnel magnetoresistive effect element,
S _D / S _U > 1
It is. On the other hand, in the present invention,
S _D / S _U <1
It is. Except for this point, the nonvolatile magnetic memory device provided with the tunnel magnetoresistive effect element of the present invention shown in FIG. 8 is the same as the nonvolatile magnetic memory device provided with the conventional tunnel magnetoresistive effect element shown in FIG. The detailed description is omitted.

  In the tunnel magnetoresistive effect element, a current in one direction is supplied to the write word line RWL which is the data write method described in the prior art, and a current in the positive direction or the negative direction is applied to the bit line depending on the data to be written. The toggle mode described in US Pat. No. 6,545,906 B1 and US Pat. No. 6,633,498 B1 can be employed. Here, the toggle mode refers to the data recorded in the magnetoresistive element by flowing a current in one direction to the write word line RWL and flowing a current in one direction to the bit line without depending on the data to be written. This is a method of writing data to the magnetoresistive effect element only when the data to be written is different. In addition, the data read line can be used for the data read without using the bit line. In this case, the bit line is electrically insulated from the recording layer (second ferromagnetic layer) above the recording layer (second ferromagnetic layer) via the upper interlayer insulating layer. It forms in the state. A data read line electrically connected to the recording layer (second ferromagnetic layer) may be provided separately.

FIG. 1 is a schematic partial cross-sectional view of the nonvolatile magnetic memory device of the example. 2A to 2C are schematic partial end views of a lower insulating layer and the like for explaining a method for manufacturing a memory element having a magnetoresistive effect according to the first embodiment. 3A to 3D are schematic partial views of the lower insulating layer and the like for explaining the method of manufacturing the memory element having the magnetoresistive effect of the first embodiment, following FIG. 2C. It is an end view. 4A and 4B are schematic partial end views of a lower insulating layer and the like for explaining the method of manufacturing the memory element having the magnetoresistive effect of the first embodiment. 5A and 5B are schematic partial end views of a lower insulating layer and the like for explaining a method of manufacturing a memory element having a magnetoresistive effect according to the third embodiment. 6 (A) and 6 (B) are schematic partial views of a lower insulating layer and the like for explaining the method of manufacturing the memory element having a magnetoresistive effect of Example 3 following FIG. 5 (B). It is an end view. 7A and 7B are schematic partial end views of a lower insulating layer and the like for explaining a method for manufacturing a memory element having a magnetoresistive effect according to the fourth embodiment. FIG. 8 is a schematic partial sectional view of a TMR type nonvolatile magnetic memory device of the present invention. FIGS. 9A and 9B are a conceptual diagram of a spin-injection magnetoresistive effect element to which spin-injection magnetization reversal is applied, and a schematic plan view of a magnetization reversal layer. FIG. FIG. 9 is a schematic diagram showing a state in which the magnetization direction of the magnetization reference layer is fixed by exchange coupling with the antiferromagnetic material layer in the spin-injection magnetoresistive effect element. FIG. It is a conceptual diagram of a spin injection type magnetoresistive effect element having a spin filter structure. FIG. 10 is a schematic partial cross-sectional view of a conventional TMR type nonvolatile magnetic memory device. FIG. 11 is a graph showing the relationship between the memory cell size and the write current. 12A to 12C are schematic partial end views of a lower insulating layer and the like for explaining a conventional method of manufacturing a memory element having a magnetoresistive effect. 13A and 13B are schematic partial end views of a lower insulating layer and the like for explaining a conventional method for manufacturing a memory element having a magnetoresistive effect, following FIG. 12C. It is.

Explanation of symbols

TMJ: Tunnel magnetoresistive effect element, TR: Selection transistor, BL: Bit line, RWL: Write word line, 10: Semiconductor substrate, 11: Element isolation region, 12. ..Gate electrode, 13 ... Gate insulating film, 14A, 14B ... Source / drain region, 15 ... Contact hole, 16 ... Sense line, 21, 24 ... Lower insulating layer, 22, 25... Connection hole, 23... Landing pad, 26... Interlayer insulating layer, 30... Magnetoresistive effect element (spin injection type magnetoresistive effect element), 41. 42 ... second wiring, 50, 50A, 150 ... stacked structure, 51, 51A, 51B ... magnetization reference layer, 52, 52A, 52B ... non-magnetic film (tunnel insulating film) 53, 53A, recording layer, 4, 54A, 54B ... antiferromagnetic layer, 61, 61A, 161 ... cap layer, 62, 62A ... connection, 151 ... first ferromagnetic layer, 151A ... Antiferromagnetic layer, 151B ... magnetization fixed layer, 152 ... tunnel insulating film, 153 ... second ferromagnetic layer, 71, 81 ... resist layer, 73, 83 ... opening 74, 84 ... side wall, 74A ... side wall forming layer, 80 ... opening forming layer

Claims (5)

(A) a laminated structure having a recording layer;
(B) a first wiring electrically connected to the lower part of the laminated structure; and
(C) a second wiring connected to the upper part of the laminated structure via a connection part;
A method for manufacturing a memory element having a magnetoresistive effect, comprising:
(A) After forming an unpatterned laminated structure on the first wiring,
(B) On the laminated structure, a resist layer in which an opening is provided in a portion where a connection portion is to be formed is formed, and then
(C) After forming the connection portion in the opening provided in the resist layer, the resist layer is removed, and then
(D) patterning at least the recording layer constituting the laminated structure using the connection portion as a mask;
Comprising steps ,
When the area of the lower end surface of the connecting portion in contact with the laminate structure S _D, the area of the upper surface of the connection portion in contact with the second wiring and the S _U,
S _D / S _U <1
A method for manufacturing a memory element that satisfies the requirements. The magnetoresistive effect according to claim 1, wherein between the step (B) and the step (C), the size of the opening is reduced by forming a sidewall on the side wall of the opening provided in the resist layer. A method for manufacturing a memory device having The method of manufacturing a memory element having a magnetoresistive effect according to claim 1, wherein the formation of the connection portion in the opening provided in the resist layer in the step (C) is based on a plating method. The method of manufacturing a memory element having a magnetoresistive effect according to claim 1, wherein patterning is performed by a dry etching method or an ion milling method in the step (D). 2. The method of manufacturing a memory element having a magnetoresistive effect according to claim 1, wherein the memory element having a magnetoresistive effect comprises a spin injection type magnetoresistive effect element.

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