JP2002280526A - Reluctance storage element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem of a current-drive device, i.e., a reluctance storage element, that an operation becomes instable as a pulse waveform is disturbed, a high speed operation becomes difficult due to the mismatch of impedance of a line for applying a field and the element is susceptible to magnetic crosstalk as the degree of integration is increased. SOLUTION: The reluctance storage element comprises a reluctance element and a wire for applying a field to the element wherein the line comprises two or more conducting wires extending in the same direction. By applying a field to one element using a plurality of lines of conducting wires, high speed response can be attained while suppressing the magnetic crosstalk.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetoresistive storage element utilizing a magnetoresistance effect, and more particularly to a magnetoresistive storage element suitable for high-speed pulse transmission.

[0002]

2. Description of the Related Art Solid state using a magnetoresistive element (MR element)
Magnetic random access memory as storage device
(MRAM) is being studied. MRAM is an MR element
Word line for generating a recording magnetic field to
And a conductive line including a sense line. Conventionally, M
The RAM has a magnetoresistance change rate (MR change rate) of about 2%.
A NiFe film or the like exhibiting an anisotropic MR effect (AMR) is used.
However, improvement of output was a problem. Through non-magnetic film
Giant magnetism made of artificial lattice film consisting of magnetic film exchange-coupled
After it was discovered to exhibit a resistance effect (GMR), G
An MRAM using an MR film has been proposed. But anti
A GMR film made of a ferromagnetic exchange-coupled magnetic film has a large size.
Despite showing the MR change rate, the applied voltage is larger than that of the AMR film.
Large information recording current and readout due to need of magnetic field
Requires current. For the exchange-coupled GMR film,
As a coupling type GMR film, there is a spin valve film.
A configuration using a conductive film or a configuration using a (semi) hard magnetic film is proposed.
Is being planned. From spin valve film, same as AMR film
With a low magnetic field, a higher MR ratio than the AMR film can be obtained.
You. Further, a GMR film in which the nonmagnetic layer is a conductor film of Cu or the like
On the other hand, the non-magnetic layer _TwoO_ThreeUsing an insulating film such as
MRAM using a GMR (TMR) film has also been proposed.
I have. RAM utilizing the magnetoresistance effect is, in principle,
Non-volatile memory can be configured, which is advantageous for high speed and high integration.
Therefore, it is regarded as a promising next-generation memory.

[0003] Non-volatile memories currently mainly used include:
Although this is a flash memory, this write operation requires MO
A so-called voltage drive in which the S transistor is driven by a high-speed voltage pulse is used. Voltage drive is also applied to ferroelectric memories at the research and development level.

[0004]

In contrast, MRAM
Is a current driven device. In order to record information on an MR element, it is necessary to generate a pulse magnetic field by applying a pulse current to a conductive line (word line) arranged around the element. Therefore, the operation of the MRAM becomes unstable when the pulse waveform is disturbed. Therefore, the impedance mismatch of the word line makes it difficult to operate the MRAM at high speed.

[0005] Further, in the MRAM, magnetic crosstalk is likely to occur as the degree of integration increases. The magnetic crosstalk is a magnetic field noise applied to an MR element by a pulse current transmitted on an adjacent word line. Since this noise may cause loss of recorded information, it becomes an obstacle to improving the integration degree.

[0006]

As in the prior art, one M
If a single-line word line is used for writing information to the R element, the impedance matching of this line is limited, and magnetic crosstalk cannot be sufficiently suppressed. Therefore, in the present invention, a word line for one element includes a double line extending in the same direction. That is, the magnetoresistive storage element of the present invention includes a magnetoresistive element and a wiring for applying a magnetic field to the magnetoresistive element, and the wiring includes two or more conductive lines extending in the same direction. Features.

According to the present invention, the impedance matching of the pulse transmission line is facilitated, the delay coefficient is reduced, and the distortion of the pulse waveform can be suppressed. Therefore, MR
High-speed response in AM becomes possible. Further, according to the present invention, the coupling between adjacent word lines can be relatively weakened. Therefore, magnetic crosstalk in the MRAM can be easily reduced.

[0008]

Embodiments of the present invention will be described below with reference to the drawings.

In FIG. 1, a magnetoresistive element (MR element) 10
Word lines 11 and 12 composed of two conductive lines are provided for writing information to the memory cells. The sense line 20 is arranged so that its extending direction forms an angle of 90 degrees with the extending direction of the word line. Each of the word lines 11 and 12 is composed of two conductive films that are spaced apart from each other via an insulating film (not shown). In the following drawings, well-known members such as an insulating film are omitted as appropriate for simplification.

[0010] Since the conventional word line is a single line, its coupling with another conductive line or the like adjacent to each part becomes dominant. For this reason, it has been difficult to achieve impedance matching. However, when two or more conductive lines are used for translation, the characteristic impedance of the word line can be easily controlled.

The conductive lines 11 and 12 only need to extend in the same direction as each other at a portion where a pulse magnetic field for writing information is applied to the element, and the arrangement in the remaining regions is not limited. In order to obtain a predetermined characteristic impedance, the conductive wires 11 and 12 are preferably maintained at a predetermined distance from each other in the above-described portion.

[0012] The use of a double line can realize a low characteristic impedance that cannot be realized by a conventional single line. The characteristic impedance of the multiple line composed of two or more conductive wires is not particularly limited, but is preferably 5 kΩ or less, and particularly preferably about 1 Ω to 1 kΩ. In order to realize such a characteristic impedance, it is preferable that the interval between two or more conductive lines forming the multiple line is maintained, for example, in a range of 0.05 to 10 μm.

In order to impart shape anisotropy to the magnetic film of the MR element 10, the surface shape of the element is preferably L ₁ ≠ W ₁ . However, the shape of the MR element is not limited to the illustrated rectangular parallelepiped, and may be various prisms, cylinders, truncated cones, truncated pyramids, or the like.

FIGS. 2A to 2C show examples of the dependence of line impedance on the number of pulse clocks in a transmission line for generating a pulse magnetic field. Here, the width of the conductive line forming the line was 0.2 μm. In order to integrate the elements, the width and the thickness of the conductive line are each preferably 1 μm or less. As a material of the interlayer insulating film (Layer-I, Layer-II, LayerIII), aluminum oxide (dielectric ratio: about 8.
5, dielectric loss tangent: about 0.01). The distances d1 and d2 between the upper and lower ground planes 30 (the upper ground plane is not shown) and the conductive lines were both 100 μm.

When a single-layer conductive line 31 is used (FIG. 2)
(A), (B)), in order to set the characteristic impedance to 50Ω, it was necessary to reduce the distance d1 between the conductive wire 31 and the ground plane 30 to about 0.2 μm (FIG. 2).
(A)). In the MRAM, since a multilayer film is required for forming elements and wirings, the distance d1 must be large. However, when d1 was set to 100 μm in consideration of this, the impedance greatly shifted to the high impedance side (FIG. 2B).

When the double conductive lines 31 and 32 are used, even if the distance d1 between the conductive line 32 and the ground plane 30 is increased to about 100 μm, the distance d3 between the two conductive lines is maintained at about 0.2 μm. And the characteristic impedance Z could be matched to 50Ω. In the arrangement shown in FIG. 2 (C), it was confirmed that even when the frequency of the pulse current reached about 10 GHz, the consistency was almost maintained.

A preferable value of d3, that is, a preferable distance between a pair of conductive lines arranged so as to face each other differs depending on the width w of the conductive line. This range is generally defined by the formula: w
/ 10 ≦ d3 ≦ 5w (where w ≦ 1 μm).

When silicon oxide or magnesium fluoride is used as the interlayer insulator instead of aluminum oxide, the dielectric constant and the dielectric loss tangent change.
Although the optimum value slightly changed, there was no change in that the two layers of conductive wires facilitated impedance matching.

It has been confirmed that the magnetization reversal operation of the ferromagnetic material has a response at several hundred MHz. For high-speed operation utilizing such characteristics, it is desirable to transmit a current pulse without distortion or delay. When a multi-line word line is used, even in pulse transmission of ns order or less, for example, 0.1 ns or less,
Waveform distortion and the like can be suppressed.

At the time of writing information, the sense line 2
A current may flow through zero. The element 10 has word lines 11,
This is because the use of the composite magnetic field H _R of the magnetic field H _W by the magnetic field 12 and the magnetic field H _S by the sense line 20 requires a small magnetic field for writing. As shown in FIG. 3, when a magnetic field is applied such that the magnetic field H _W and the magnetic field H _S are 1: 1 at the operating point (in other words, the angle θ of the magnetic field H _R with respect to the magnetic field H _W) .
Is 45 °), the write magnetic field can be minimized.

The conductive lines constituting the double line are not limited to the arrangement shown in FIG. 1, but may be arranged so as to sandwich the MR element, for example. When an MR element using a pair of conductive lines arranged so as to sandwich the efficient magnetic field H _W can be applied. FIG.
As shown in FIG. 5, the direction in which the element 10 is sandwiched between the conductive lines 12 and 13 is preferably the lamination direction of the multilayer film constituting the MRAM. However, as shown in FIG. The conductive wires 14 and 15 may be arranged so as to sandwich the wire 10.

When only the MR element 10 and the conductive lines 12 and 13 are displayed, the arrangement of FIG. 4 is as shown in FIG.
A pair of conductive wires 12, 1 arranged to sandwich the element
3 is preferably coupled in an odd mode. This is because when a pulse current is applied to one conductive line, a pulse having an opposite phase propagates to the other conductive line, and a pulse magnetic field in the same direction is applied to the element from both conductive lines.

The number of conductive lines extending in the same direction may be three or more. For example, in FIG. 7, additional conductive lines 16,
17 are arranged. In this case, four conductive wires 1
It is preferable to arrange the conductive wires so that a desired characteristic impedance is obtained in the whole of 2, 13, 16, and 17.

A signal line (signal drive line) for inputting a current for applying a magnetic field and a passive line (coupled passive line) held at a predetermined potential are connected to two or more conductive lines constituting the double line.
Is preferably included. The passive line is preferably dropped to ground potential, but need not be at ground potential as long as it is maintained at a predetermined potential. The signal line and the passive line are preferably capacitively coupled so that a pulse current corresponding to the pulse current input to the signal line is generated in the passive line.

FIGS. 8B to 8F show examples of the arrangement of the signal lines 31 and the passive lines 32. For simplicity, the illustration of the MR element is omitted, but in these figures, one signal line 31 is shown.
, And this element is disposed between the signal line 31 and the passive line 32 facing the signal line 31 (thus, three MR elements are not shown in each drawing. There).

As shown in FIG. 8A, the conventional single conductive line 31 is more easily coupled to another signal line adjacent to the ground plane 30. This coupling causes a malfunction. On the other hand, in FIGS. 8B to 8F, two or more conductive lines extend in the same direction for one MR element, and the two or more conductive lines include the signal line 31 and the ground. At least one passive wire 3 located closer to the signal line than surface 30
2, 33 are included. The illustrated configuration is an array that is particularly effective for high-speed pulse transmission and suppression of magnetic crosstalk.

In each of the embodiments shown in FIGS. 8B to 8F, the passive line 32 is disposed at a position facing the signal line 31 via an element not shown. In contrast, the passive wire 33
Are arranged on the same side as the signal line 31 as viewed from the element, and are interposed between the signal lines 31 and 31. The presence of the passive wire 33 is effective in further suppressing magnetic crosstalk.
That is, a first signal line and a second signal line for inputting a current for applying a pulse magnetic field to the first MR element and the second MR element are provided, and the first signal line and the second signal line extend in the same direction. In this case, at least one passive line held at a predetermined potential is connected to the first signal line and the second signal line.
It is good to arrange between signal lines. The preferred arrangement of the passive line 33 includes in the same plane as the adjacent signal lines 31, 31 (first signal line and second signal line). Here, the term "within the same plane" refers more precisely to the same plane of the multilayer film constituting the MRAM.

As described above, the passive line 32 is connected to the signal line 31.
And in an odd mode. On the other hand, in order to more effectively suppress magnetic crosstalk, the passive line 33 may be coupled to at least one of the adjacent signal lines 31 (more preferably, both) in an even mode.

If the passive line 33 is regarded as a first passive line, the passive line 32 is a second passive line, and this second passive line is adjacent to the first passive line, preferably along the stacking direction of the multilayer film. The signal line 31 is arranged so as to sandwich the MR element with either one of the signal lines 31.

In the embodiment shown in FIG. 8B, a pulse magnetic field can be effectively applied from the signal line 31 and the passive line 32 to the MR element therebetween. 8C is slightly inferior to the embodiment of FIG. 8B from the viewpoint of improving the degree of integration of the element, but the passive line 33 disposed between the adjacent signal lines 31 has an effect of magnetic crosstalk. Restrained. Each of the embodiments shown in FIGS. 8D to 8F has the advantages of both embodiments. In FIG. 8 (E), the line width of the passive line 32 is wider than that of the signal line 31 so that
In FIG. 8F, by arranging a plurality of passive lines 33 between adjacent signal lines, magnetic field leakage is further suppressed.

The arrangement of the signal lines and the passive lines is not limited to the above-described embodiment. For example, as shown in FIGS. 9A to 9C, the signal lines 31 do not necessarily need to be formed in the same plane. As shown in these figures, by arranging the signal lines 31 in two or more planes and arranging the passive lines 34 and 35 between the signal lines in those planes, the magnetic crosstalk is suppressed while increasing the degree of integration. can do.

For example, in FIG. 9B, the passive line 34a is
MR element (not shown) sandwiched between opposing signal lines 31a
To apply a pulsed magnetic field to the adjacent signal line 31
b, 31c can simultaneously play the role of suppressing the leakage magnetic field. In this manner, the passive line may be arranged so as to sandwich the MR element together with the signal line and to be in the same plane as another adjacent signal line. Again, the passive wire 34a
Is an odd mode with respect to the signal line 31a, and the in-plane signal line 31
Preferably, b and c are coupled in even mode.

The odd mode or even mode coupling can be realized by adjusting the distance between the conductive lines and the terminating resistance value.
When the driving capability of the input driver is increased, impedance mismatch is likely to occur, but this mismatch may be removed by adding a terminating resistor. As shown in FIG.
The terminating resistor includes a resistor 41 arranged in parallel with the driver 40,
It is preferable to use a latch type having a driver 42 and a resistor 42 interposed in series between the word line 45 and the driver 40. Here, the terminating resistance can be represented by the sum of the resistances 41 and 42. The value of the terminating resistance value may be adjusted as appropriate, but is generally adjusted to approximately Z ² / R using the characteristic impedance Z and the driver resistance R (for example,
It is preferable to adjust so as to fall within a range of ± 10% from this value).

As shown in FIG. 11, in the MRAM, a plurality of magneto-resistive elements are arranged, for example, in a matrix. In this MRAM, a sense line 54 extends along a column constituted by the elements 50, and a word line 51 and a bit line 53 extend along a row direction orthogonal to the column. Recording and reading of information from and to elements arranged in a predetermined number of columns and rows are performed by decoding function units 55 and 56 and data exchange units 57 and 5 arranged around the element group.
8 is performed.

As shown in FIG. 12, the word line 51 is
Actually, it is an impedance-matched double line extending in the same direction. Word lines 51 are preferably coupled to each other in an odd mode, and elements 50
Then, a combined magnetic field is applied together with the sense line 54.

As described above, the present invention includes a plurality of MR elements arranged in a matrix in a predetermined plane and a wiring for applying a magnetic field to the plurality of MR elements. And the wiring includes a magnetoresistive storage element including, for each of the plurality of element rows, two or more conductive lines extending along the element row. It is preferable that the two or more conductive wires include a pair of conductive wires 51 arranged so as to sandwich the predetermined surface. As shown in FIG. 12, the two or more conductive lines may be constituted by only a plurality of conductive lines arranged apart from the element 50.

A specific configuration when the MR element is used in combination with a MOS transistor will be described below. The MR element 50 shown in FIG. 13 is connected to a MOS transistor 60 having a gate portion 61, a source region 62, and a drain region 63, and forms a storage cell. The MOS transistors are separated from each other by a thermal oxide film 64. FIG. 14 shows an equivalent circuit of the element group in FIG. In order to prevent electrostatic breakdown of the element, it is preferable to configure the circuit shown in FIG. In this circuit, the MR element 50 is connected to the sense line 54 via the MOS transistor 60. In order to realize this circuit, for example, as shown in FIG.
M may be formed.

In order to more efficiently apply a magnetic field to the MR element, a ferromagnetic material may be arranged around the conductive wire. If a ferromagnetic material is arranged between the conductive line made of a non-magnetic material and the MR element, a magnetic field can be efficiently applied to the MR element. When a ferromagnetic material is arranged on the opposite side to the MR element when viewed from the conductive line made of a nonmagnetic material, leakage of a magnetic field can be suppressed. In order to suppress magnetic crosstalk, a ferromagnetic material may be arranged between an adjacent MR element or a conductive line for applying a magnetic field to this element. It is preferable that the ferromagnetic material is arranged so as to be in contact with the conductive line constituting the pulse transmission line. FIG. 17 shows an example in which a ferromagnetic material is added to the configuration of FIG.
(A) to (F). The ferromagnetic material 90 of FIG.
Improves the efficiency of applying a magnetic field to an element (not shown) between the conductive lines 31 and 32, and the ferromagnetic material 90 in FIGS. 17A, 17E, and 17F suppresses magnetic crosstalk. FIG.
As shown in (B) and (D), a ferromagnetic material 90 may be added so that both of the above effects are achieved.

In order to efficiently apply a magnetic field, the cross section of at least one conductive line forming the multiple line may be shaped so that the width increases as it approaches the element. For example, when the cross section of the conductive wire 11 (FIG. 1) is a trapezoid whose base angles h and h ′ contacting the base on the element 10 side are acute angles as shown in FIG. 18, efficient application of a pulse magnetic field is possible. Becomes

As the MR element constituting the MRAM, a conventionally used MR element can be used without any particular limitation. FIGS. 19A to 19G illustrate the configuration of the MR element. A magnetic layer 71 whose magnetization is relatively unlikely to be reversed and a magnetic layer 73 whose magnetization is relatively easily reversed may be laminated via an intermediate layer 72 (FIG. 19A). In order to fix the magnetization of the fixed magnetic layer 74, the antiferromagnetic layer 76 is fixed.
May be used to form a spin-valve element (FIG. 19).
(B)). A fixed magnetic layer 74 may be disposed on both sides of the free magnetic layer 75 (FIG. 19C). A pair of magnetic films 81 and 83 that are antiferromagnetically exchange-coupled to each other via the intermediate film 82
A ferrimagnetic layer composed of a layer 71 having a relatively high coercive force (FIG. 19D) or a pinned magnetic layer (FIG. 19D).
(E) may be used. Similarly, a pair of magnetic films 8 anti-ferromagnetically exchange-coupled to each other via the intermediate film 85.
A stacked ferrimagnetic layer composed of 4, 86 may be used as the free magnetic layer 75 (FIG. 19F). A double junction element may be formed by using the laminated ferri-fixing layer 74 and the laminated ferri-free layer 75 (FIG. 19G).

In these MR elements, the magnetic layers 73 and 75
The change in the resistance of the element due to the rotation of the magnetization in is detected. Even if the MR element is a TMR element, the CPP (Curr)
entPerpendicular to the Plane)-It may be a GMR element. Note that the thickness of one magnetic layer is preferably 1 nm or more and 10 nm or less.

The magnetic material constituting the MR element is not particularly limited. “(Semi) hard” magnetic materials suitable for the high coercivity layer 71 and the pinned magnetic layer 74 include Co, CoFe, N
iFe, NiFeCo and the like are suitable. In particular, Co or CoFe is suitable for achieving a large MR ratio.
Therefore, it is preferable to use Co or CoFe at least at the interface with the nonmagnetic layer. The preferred composition of CoFe is CoyFez, where 0.2 ≦ y ≦ 0.
95, 0 ≦ z ≦ 0.5.

XMnSb (X
Is preferably a metal element, particularly at least one selected from Ni, Pt, Pd and Cu).
The ratio is obtained.

MFe ₂ O ₄ (M is F
e, at least one element selected from Co and Ni) is also preferable. This material exhibits ferromagnetism up to a relatively high temperature, and Co and Ni rich have extremely high resistance compared to Fe rich. Co-rich has large magnetic anisotropy. Desired characteristics can be realized by adjusting the enemies composition ratio.

As a “soft” magnetic film suitable for the free magnetic layer 75 and the like, a NiCoFe alloy is generally suitable.
The atomic composition ratio of the NiCoFe film is Ni _x Co _y Fe
Represented by _z , 0.6 ≦ x ≦ 0.9, 0 ≦ y ≦ 0.
4, Ni-rich film of 0 ≦ z ≦ 0.3 or Ni _{x ′} Co
Display by _{y 'Fe z', 0 ≦} x '≦ 0.4,0.2 ≦
A Co-rich film with y ′ ≦ 0.95 and 0 ≦ z ′ ≦ 0.5 is suitable.

Materials suitable for the antiferromagnetic layer 76 include IrMn, RhMn, RuMn, and CrPt of an irregular alloy type.
Mn and the like. For these materials, a process that can be exchange-coupled with a magnetic film by forming a film in a magnetic field is simple. Ordered alloy NiMn, Pt (Pd)
Mn and the like require heat treatment for ordering, but are excellent in thermal stability. Of these materials, PtMn is preferred. Α-Fe ₂ O ₃ , N which is an oxide antiferromagnetic material
iO and LTO ₃ (L is at least one selected from rare earth elements other than Ce, and T is at least one selected from Fe, Cr, Mn and Co) may be used. In the case of using an oxide having a high resistivity, it is necessary to form an electrode portion so as to make direct contact with the magnetic layer so that the electrical characteristics do not reflect the high resistivity.

The materials of the word lines, sense lines, and bit lines are not particularly limited, and Al, Cu, Pt, Au, or the like may be used.

[0048]

(Embodiment 1) FIG.
An MR element having the multilayer configuration shown in FIG. 9 (F) was manufactured. The film configuration of this substrate is shown below.

Ni _0.81 Fe _0.19 (2) / Ru (0.
7) / Ni _0.81 Fe _0.19 (3) / Al ₂ O ₃ (1.
2) / Co _0.75 Fe _0.25 (2) / Ru (0.7) /
_{Co 0. 75 Fe 0.25 (2)} / PtMn (20) ( However, the display from the membrane top in this order. Parentheses thickness (n
Here, the Al ₂ O ₃ layer serving as a tunnel insulating layer is prepared by oxidizing Al formed by a sputtering method (type A) or by sputtering Al ₂ O ₃ as it is. (Type B) was prepared. In type A, oxidation was performed by any of natural oxidation in a vacuum tank, natural oxidation under heating in a vacuum tank, and oxidation by oxygen-containing plasma in a vacuum tank. A non-magnetic insulating film functioning as a tunnel barrier was obtained by any of the steps. Also,
A type B non-magnetic insulating film functioning as a good tunnel barrier was obtained. Each film thickness was controlled by a shutter. The element area (junction area) was 0.12 μm ^{2 for} each type.

The MR characteristics of the MR element thus manufactured were measured at room temperature, at an applied magnetic field of 100 Oe (about 7.96 kA / m),
When measured at a bias voltage of 100 mV, an MR ratio of about 30% was obtained. The magnetic field width in which MR occurs was 10 Oe.

Using this MR element, an MRAM having the structure shown in FIGS. 11 and 12 was manufactured. As the substrate, a silicon substrate on which a MOS transistor was formed for each MR element by a semiconductor process in advance was used. Silicon oxide is used as an interlayer insulating film between the transistor and the magnetoresistive element,
Aluminum oxide was used for insulation between the MR element and the word line.

Copper was used for the sense lines and the bit lines, and copper was also used for the word lines. The distance between a pair of conductive lines arranged as word lines is 0.35 μm, the width of each conductive line is about 0.5 μm, the thickness of each conductive line is about 0.5 μm, and the distance between conductive lines between adjacent element columns. Was about 0.6 μm.
A terminating resistor was arranged at the end of the wiring, and the characteristic impedance of the word line was adjusted to about 75Ω. For the wiring, one of the conductive lines was dropped to ground potential to be a passive line, and the other was a signal line.

In this MRAM, recording and reading operations of 16 bits of information per word were confirmed.

Using the MRAM, transmission of a pulse signal to a word line was examined in detail. 1 for signal line
When a pulse current was input under the input conditions of a pulse rise from V to 5V of 1 ns and a propagation time of 0.5 ns (wiring length: about 10 cm), the signal rose at 1 ns. Further, as compared with the case where a single-line word line was used, large reflection of a signal at the near end and the far end of the word line was not observed from the pulse transmitting side.

Under the above input conditions, the influence of crosstalk between wirings was investigated. In this investigation, an MRAM in which the distance between adjacent conductive lines was about 0.6 μm was used. At this time, as compared with the case where the word line was a single line, the appearance of a large signal at the near end and the far end as viewed from the pulse transmitting side was not recognized in the adjacent conductive line.

In this arrangement, it was confirmed that even-mode coupling appeared by changing the distance between adjacent conductive lines. Further, it was confirmed that by adjusting the terminating resistance, the odd mode coupling also appeared.

(Embodiment 2) As in Embodiment 1, FIG.
0 (A) to M (F) where word lines are arranged as shown in (F).
A RAM was manufactured. The word line includes the signal line 91 and the passive line 9
2,93. Passive line 92 is connected to signal line 91 and M
An R element (not shown) is arranged so as to sandwich the passive element 9.
3 is formed in the same plane as the signal line 91. FIG.
In (F), one signal line corresponds to one MR element.

The line width of each of the signal line 91 and the passive line 92 was 0.2 μm. In any of the MRAMs, the lower ground plane 100 and the nearest conductive line 91
To 93, and the distance between the upper ground plane (not shown) and the signal line 91 were 100 μm.

In these MRAMs, when a one-word signal was sent, malfunctions of adjacent non-selected memories were evaluated for a population of 1,000. Table 1 shows the results.
In Table 1, d is the distance between the signal line 91 and the passive line 92;
w is the interval between adjacent signal lines 91, 91, and Wm is the passive line 9
3 is the line width.

[0060]

[Table 1]

(Embodiment 3) MRA is performed in the same manner as in Embodiment 1.
M was produced. However, here, as shown in FIG. 8D, in addition to the pair of conductive lines 31 and 32, the conductive line 33 was formed between adjacent elements.

Using this MRAM, word lines 31 to 3
Experiment 3 was conducted. Line width is about 0.5μ
m, the line thickness was about 0.3 μm, and the distance between adjacent conductive lines was about 0.3 μm. A terminating resistor for adjustment was provided at the end of the wiring, and the characteristic impedance was adjusted to about 75Ω.

The rise of the applied pulse from 1 to 5 V is 1 ns, and the propagation time is 0.5 ns (wiring length: about 10 c
Under the input condition of m), the signal showed a rise at 1 ns. Also in the present embodiment, compared to the case of the single wiring, no large signal reflection or the like was observed at the near end and the far end of the wiring when viewed from the pulse transmitting side.

Next, under the above-mentioned input conditions, the influence of crosstalk between adjacent wirings was evaluated. Here, the distance between adjacent conductive lines is about 0.35 μm, and the distance between the signal lines 31 is 31 μm. As compared with the case of the single wiring, no large signal appeared at the near end and the far end of the adjacent wiring when viewed from the pulse transmission side. 8D, the appearance of a large signal at the near end and the far end of the adjacent wiring was suppressed as compared with the configuration of FIG. 8C that was tested for comparison.

In this wiring, even mode coupling appeared when the distance between adjacent conductive lines was in the range of about 0.1 to 1 μm. Further, when the terminating resistance was adjusted in the range of 10Ω to 100kΩ, odd mode coupling appeared.

[0066]

As described above, according to the present invention,
Since the impedance matching of the pulse transmission line is facilitated, the delay coefficient is reduced and the distortion of the pulse waveform can be suppressed. Therefore, a high-speed response in the MRAM is possible. Further, according to the present invention, the coupling between adjacent word lines can be relatively weakened. Therefore, MRA
Magnetic crosstalk at M can be easily reduced.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an example of wiring around an MR element according to the present invention.

FIGS. 2A to 2C are diagrams showing the relationship between the pulse clock dependence of the impedance of a pulse transmission conductive line and the arrangement of the conductive lines. FIGS. (C) shows the above relationship in a conventional single line, and (C) shows the above relationship in an example of the present invention.

FIG. 3 is a diagram showing operating points when a combined magnetic field of a magnetic field by a word line and a magnetic field by a sense line is used.

FIG. 4 is a perspective view showing another example of the wiring around the MR element according to the present invention.

FIG. 5 is a perspective view showing another example of the wiring around the MR element according to the present invention.

6 is a simplified cross-sectional view of the arrangement example of FIG.

FIG. 7 is a cross-sectional view showing still another example of the wiring around the MR element according to the present invention.

FIGS. 8A to 8F show wiring examples of conductive lines (signal lines and passive lines). (A) is 1 for one element.
(B) to (B) indicate conventional wirings corresponding to only the signal lines.
(F) is a wiring example according to the present invention, in which one signal line and at least one passive line correspond to one element, and these conductive lines extend in the same direction. Is shown.

FIGS. 9A to 9C show another example of the arrangement of signal lines and passive lines in the present invention.

FIG. 10 shows an example of a termination resistor arrangement.

FIG. 11 is a plan view showing an example of an MRAM to which the present invention is applied.

FIG. 1 is a diagram showing the vicinity of an element together with a generated magnetic field.
FIG. 2 is a partially enlarged view of FIG.

FIG. 13 is a sectional view showing a connection example between a MOS transistor and an MR element.

14 is a partial wiring diagram of an MRAM to which the arrangement of FIG. 13 is applied.

FIG. 15 is a cross-sectional view showing another example of the connection between the MOS transistor and the MR element.

16 is a partial wiring diagram of an MRAM to which the arrangement of FIG. 15 is applied.

FIGS. 17A to 17F respectively show FIGS.
FIG. 4 is a cross-sectional view showing an example in which a ferromagnetic material is added to a pair of signal lines.

FIG. 18 is a cross-sectional view illustrating an example of a conductive line having a cross section other than a rectangle.

FIGS. 19A to 19G are cross-sectional views each showing an example of a film configuration of an MR element applicable to the present invention.

20 (A) to 20 (F) show M produced in Example 2. FIG.
FIG. 2 is a simplified perspective view showing wiring of word lines of a RAM.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 Magnetic resistance element (MR element) 11, 12, 13, 14, 15, 16, 17 Conductive line (word line) 20 Conductive line (sense line) 30 Ground plane 31 Conductive line (signal line) 32, 33, 34, 35 conductive line (passive line) 40 driver 41, 42 resistor 45 conductive line (word line) 50 magnetoresistive element (MR element) 51 conductive line (word line) 54 conductive line (sense line) 55, 56 decoding function unit 57, 58 Data exchange unit 60 MOS transistor 71, 73 Magnetic layer 72 Intermediate layer 74 Fixed magnetic layer 75 Free magnetic layer 76 Antiferromagnetic layer 90 Ferromagnetic material

Continuation of the front page (72) Inventor Nozomi Matsukawa 1006 Kazuma Kadoma, Kazuma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. F term (reference) 5F083 BS13 BS37 FZ10 JA02 JA36 JA37 JA38 JA60 KA01

Claims (13)

[Claims] 1. A magnetoresistive storage element comprising: a magnetoresistive element; and a wiring for applying a magnetic field to the magnetoresistive element, wherein the wiring includes two or more conductive lines extending in the same direction. 2. The magnetoresistive storage element according to claim 1, wherein the two or more conductive lines have a characteristic impedance of 5 kΩ or less. 3. The magnetoresistive storage element according to claim 1, wherein the two or more conductive lines include a pair of conductive lines arranged so as to sandwich the magnetoresistive element. 4. The magnetoresistive storage element according to claim 3, wherein said pair of conductive lines are coupled in an odd mode. 5. The device according to claim 1, wherein the two or more conductive lines include a signal line for inputting a current for applying a magnetic field, and a passive line maintained at a predetermined potential. Magnetoresistive storage element. 6. A magnetoresistive element as a first magnetoresistive element, further including a second magnetoresistive element, for inputting a current for applying a magnetic field to each of the first and second magnetoresistive elements. A first signal line and a second signal line, wherein the first signal line and the second signal line extend in the same direction, and at least one passive line held at a predetermined potential is connected to the second signal line. 6. The magnetoresistive storage element according to claim 5, wherein said magnetoresistive storage element is arranged between one signal line and said second signal line. 7. The magnetoresistive storage element according to claim 6, wherein at least one of said first signal line and said second signal line is coupled to said passive line in an even mode. 8. The signal line according to claim 6, wherein the first signal line, the second signal line and the passive line are arranged in the same plane.
3. The magnetoresistive storage element according to 1. 9. The semiconductor device according to claim 9, further comprising a second passive line, wherein the passive line is a first passive line, wherein the second passive line connects one of the first magnetoresistive element and the second magnetoresistive element to the element. 9. The magnetoresistive storage element according to claim 6, wherein said magnetoresistive storage element is arranged so as to be sandwiched between said signal line and a signal line for applying a magnetic field. 10. The magnetoresistive storage element according to claim 9, wherein said second passive line and a signal line sandwiching said element together with said second passive line are coupled in an odd mode. 11. A semiconductor device comprising: a plurality of magneto-resistive elements arranged in a matrix in a predetermined plane; and wiring for applying a magnetic field to the plurality of magneto-resistive elements; A magnetoresistive storage element forming an element row, wherein the wiring includes, for each of the plurality of element rows, two or more conductive lines extending along the element row. 12. The magnetoresistive storage element according to claim 11, wherein the two or more conductive lines include a pair of conductive lines arranged so as to face each other via the predetermined surface. 13. The magnetoresistive storage element according to claim 11, wherein said wiring further includes a conductive line arranged so as to be orthogonal to said element row.