JPS62124690A - Magnetic memory element - Google Patents

Abstract

PURPOSE:To remove the ununiformity of potential well in the magnetic domain walls at the time of stabilizing of stripe domain by making ion implantation in an annular area in which an annular striped main is made to exist on the surface of a striped main holding layer. CONSTITUTION:A stripe domain holding layer 1 is attached on a substrate 2. A mask made of gold or silicon dioxide is formed on the holding layer 1 outside of the area in which the annular stripe domain 6 is to be held to prevent the irradiation of ion at the time of ion implantation, and then neon or hydrogen ion is implanted. Inside magnetic domain walls of the stripe domain are attracted to the boundary 4 of the inside ion implantation area. Outside boundary 5 of the ion implantation area is made to prevent inside magnetic domain walls from becoming too off from 4 at the time of initial setting the annular striped main 6. Thus, generation of difference in level is eliminated by ion implantation, and thereby ununiformity of potential well of the magnetic domain walls at the time of stabilizing of the stripe domain can be removed.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to nonvolatile ultra-high density solid state magnetic storage elements.

(Prior Art) Development of magnetic bubble elements using high-density solid-state magnetic memory elements is actively being carried out in various places. However, with the currently used garnet materials, the minimum attainable bubble diameter is said to be 0.3 μm.

Therefore, a bubble material that retains zero bubbles with a diameter of 03 μm or less must be found in a variety of materials other than garnet material. This is easy and fast, and is even considered to be the limit of bubble density.

We have developed an ultra-high-density magnetic memory element that is magnetized in the direction perpendicular to the film surface, which can significantly improve the density limit based on the characteristics of the bubble retention layer, and at the same time maintain the information readout time at the same level as conventional elements. A Bloch line pair (hereinafter referred to as a Bloch line pair) consists of two vertical Bloch lines that statically and stably exist within a Bloch domain wall that is the boundary of a stripe domain formed in a ferromagnetic (including ferrimagnetic) film with easy direction. VBL
It is called a pair. ) was invented as a storage unit. (Japanese Patent Application No. 57-182346) The present magnetic storage element includes an information reading means, an information writing means, and an information storage means, and the VBT.

It has means for transferring within the entire Bloch domain wall.

One of the most important parts of this device is the information storage section (hereinafter referred to as the minor loop).

In such a magnetic memory element, it is essential to stably hold the VBL pair of the striped domain domain wall, which is written as information, and to be able to selectively transfer bit by bit. As a method of maintaining stability,
-065826, along the Bloch domain wall around the stripe domain that constitutes the minor loop,
Locally changes the direction of magnetic anisotropy within the film plane. By doing so, it is possible to create positions where ■BL pairs stably exist and positions where they are most likely to exist along the stripe domain domain wall.

Regarding the other condition, selective transfer of each bit of the VBL pair, in principle it is necessary to provide means for applying a force to drive the VBL pair along the domain wall. In reality, VB
A method of applying a local in-plane magnetic field in the form of a traveling wave along the domain wall surface to the L pair existing region, and applying a pulse bias magnetic field to the stripe domain domain wall to cause the domain wall to move entirely and VDT accordingly.

It has been considered to utilize gyroscopic force, which is one of the reactions caused by the position of the pair, but the former is currently only achieved by using conductor patterns, so it is difficult to achieve high density elements. There's a problem. On the other hand, in the latter case, the domain wall driving force provided by the externally applied pulsed bias magnetic field is very important. In order to make this domain wall driving force constant at each part on the chip, it is important to determine how to stabilize the stripe domain, that is, to optimize the potential wool shape of the stripe domain domain wall.

Conventionally, as shown in Figure 3, this method involves hollowing out a region in the stripe domain holding layer l in which the stripe domain 6 is to be stabilized, and inserting a vertical A region with magnetization 8 in the opposite direction to the bias magnetic field 10 is created at the periphery of the hollowed out part by embedding magnetized material 19 and using the magnetic field leaking from that part to the outside, and minor loops drive the domain wall 7 around the outside of the region. It was used as a domain domain wall.

Alternatively, as shown in FIG. 4, grooves 3 may be formed by reductively digging only the portions of the striped domain holding layer 1 where it is desired to hold the striped domains 6 in a ring shape.

Among the boundaries of the groove, boundary 4 has a convex portion inside it with a boundary of 4, so the inner domain wall of the stripe domain 6 is
The boundary 5 serves as a stripe domain 6
When initializing , it serves as a guide so that the inner domain wall is not too far away from 4.

Furthermore, the width of the convex portion having the boundary 4 is the natural width W of the stripe domain. It is necessary to keep it above. In this way, when the striped domain 6 is held in a ring shape in the groove, the repulsive interaction between the linear domains on both sides of the convex part with the boundary 4 is strong, and the inner domain wall of the ring-shaped striped domain is fixed directly below boundary 4 and is forcefully applied. When the grooves 3 are formed so as to satisfy the above conditions, the striped domains are fixed in a ring shape with the groove boundary 4 as the inner diameter as shown in FIG.

When the striped domain is maintained in this way, the profile of the potential cool in the domain wall outside the ring-shaped domain (the domain wall that exists away from boundary 4) in the normal direction to the domain wall surface is mainly due to the demagnetizing field effect determined by the width of the striped domain. ? Therefore, it is possible to apply force without being affected by minute unevenness at the boundary of the grooved part.

When an externally applied pulsed bias magnetic field is applied to such a domain wall, the domain wall is driven uniformly over the entire domain wall 7. Therefore, when the information stored in the domain wall in the form of the presence or absence of the VBL pair is moved using the gyroscopic force generated on the VBL pair every 10 times the pulse bypass magnetic field is applied, the amount of movement is determined by the shape of the pulse bypass magnetic field. Easy to control by force.

In the figure, numerals 8 and 9 indicate the directions of magnetization inside and outside the domain, respectively.

(Problems to be Solved by the Invention) Among these stripe domain retention methods, the method of hollowing out the stripe domain retention layer and burying a perpendicular magnetization film having high saturation magnetization and high coercive force is perpendicular to the hollowed out part. Embedding the magnetized material was technically difficult and posed manufacturing problems.

Furthermore, in order to retain all the stripes in a ring shape, the method of selectively groove-cutting the area where the ring-shaped stripe domains exist requires searching for grooves in at least five stripe domain retaining layers. Due to this difference in film thickness at the groove boundary,
Difficulties have arisen in the process of forming a conductor pattern for the stripe domain formation operation, the transfer of Bloch line pairs, or the gate function, and the formation process of the insulating layer, which are laminated on the stripe domain holding layer.

The purpose of the present invention is to eliminate the drawbacks of the conventional method and to create a V B
The object of the present invention is to provide an ultrahigh-density storage element that uses VBL pairs as information units, which can stably hold the VBL pairs and selectively transfer them one bit at a time.

(Means for solving the problem) From two adjacent VBLs created in the Bloch domain wall at the stripe domain boundary existing in a ferromagnetic film whose easy direction of total magnetization is perpendicular to the film surface ■B T In a magnetic memory element used as a total storage unit, ions are implanted into the ring-shaped region where the ring-shaped stripe domains exist on the surface of the stripe domain retention layer, thereby solving the conventional manufacturing problems. Can hold ring-shaped striped domains.

A striped domain holding layer 1i is formed on the substrate 2 shown in 11th R1fa). A mask made of gold or silicon dioxide is formed on the area other than the area where the ring-shaped striped domain 6 is desired to be held, and after preparing to prevent ion irradiation during ion implantation, neon or hydrogen ions are implanted.

After the ion implantation, the smoothness of the surface of the retention layer is lost by removing the manure. Therefore, the difficulty caused by the step difference in the process of forming a conductor on the holding layer is extremely great.

The width of the ring-shaped ion implantation region is the natural width W of the ring-shaped domain. It should be larger and about 2Wo or less.

The inner domain wall of the stripe domain is attracted to the boundary 4 of the inner ion implantation region. Outer boundary of ion implantation region 5
When initializing the ring-shaped stripe domain 6,
It serves as a guide to prevent the inner domain wall from being too far away from 4. The width of the island-shaped non-ion implanted region is W.

A certain degree or more is necessary.

This is because the inner domain walls of opposing striped domains are forced to separate from each other due to repulsion, which is too strong.

As shown in FIG. 1(b), the stripe domain is fixed in a ring shape with the entire inner diameter of the ion implantation boundary 4.

When the ring-shaped striped domain 6 is held with its inner domain wall at the inner injection boundary 4, the potential of the outer domain wall (domain wall existing away from the boundary) of the ring-shaped domain is mainly determined by the demagnetizing field determined by the width of the striped domain. Determined by effect.

In this way, when the entire externally applied pulsed bias magnetic field is applied to the Hiko domain wall, the domain wall movement becomes uniform over the entire domain wall 7.

Therefore, when we store the presence or absence of the VBL pair in this domain wall and move it using the gyroscopic force generated on the VBL pair by applying the friendship@total pulse bias magnetic field 10, the amount of movement (total pulse no. Easy to control.

In the figure, numerals 8 and 9 indicate the directions of magnetization inside and outside the domain, respectively.

(Example) Examples are shown below.

Figure 2 shows the process of forming striped domains into a ring shape, and the bubble domain conversion or writing of information stored in VBL pairs within the striped domain magnetic wall, which is a necessary condition for this device, when reading. A specific example of the shape of the ion implantation pattern including the gate portion 18 for performing the function of storing data expressed in the form of the presence or absence of nodules in the major line 17 in the form of VBL pairs within the stripe domain domain wall will be explained in detail. Shows the operating process. A bubble generator consisting of a conductive pattern 12 is placed at the tip 11 of the ion implantation region 3. In advance, a bias magnetic field of 10 is applied to the entire effective chip surface.
Apply a magnetic field in the same direction as , and saturate the whole in the direction of 10. After that, an appropriate bias magnetic field H2 is applied. Thereafter, when a pulse current 13 having the shape shown in the figure is applied to this bubble generator, a bubble is generated in ll, and the bubble is injected into a stripe domain extending along region 3, and the tips of the bubbles are introduced into guide guides 14 and 4', respectively. It is shaped like a U with a K in it. For such a stripe domain, a pulse current 16 is applied to the conductor pattern 15 in the direction of the arrow, and in the region between the two conductor patterns, the part extending into the stripe domain 14 and the part 14' Join the stretched part. The joined stripe domains contract under the action of the bias magnetic field H2 and the domain wall surface tension that tries to minimize the domain wall surface energy, and finally become the first
As shown in the figure, a square stripe domain IcI is created with the ion-implanted region boundary 4 as its inner edge.The information carrier V B T is completely written into the outer domain wall 7 of this domain 6.

Groove 18.18' is a ring-shaped striped domain that stores information in the form of a pair of major line 17°17' and V RT, which expresses the emotion in the Bloch line memory with no bubble control. This is for the gate connecting the Although the depth of the ion implantation region was actually evaluated in the range from 0.5 to 40 inches of the total film thickness of the striped domain holding layer, there were many problems regarding the formation of ring-shaped striped domains.

(Effects of the Invention) The present invention eliminates the need for embedding perpendicular magnetization material, which has been a problem in the past, and allows conductor patterns, etc. By implanting ions, it is possible to reduce the problem of steps during the stacking process, and to reduce the problem of steps that previously existed during the stacking process. Kali, (+
21 The stability of Bloch line pair transfer is high, thus improving the reliability of Bloch line memory.

[Brief explanation of drawings]

1(a), (b) and 2 are diagrams showing an example of the structure of the striped domain holding layer of the present invention, and FIGS. 3 and 4 are diagrams showing a conventional example. In the figure, l varnish drive domain holding layer, 2: substrate, 3: ion implantation region, 4: inner boundary of ion implantation region, 5: outer boundary of ion implantation region, 6: ring-shaped stripe domain, 7
: Stripe domain outer peripheral domain wall, 8 inner magnetization direction of two domains, 9 outer magnetization direction of two domains, 10: bias magnetic field direction, ll: tip of grooved part (bubble generation part), 1
2: Bubble generator conductor pattern, 13: Bubble generation current, 14.14' Varnish drive domain tip introduction guide, 15 Conductor pattern for varnish drive domain fusion, 16
: Stripe domain fusion current, 17° 17': Major line (bubble transfer path), 18.18' Nidoransphage part (groove part), 19: Hard magnetic perpendicular magnetization film (material), 20: Hard magnetic perpendicular Magnetization direction of magnetized film (material), 2
1: Ion implantation layer. $ 1 Diagram A /
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Claims (1)

[Claims] In a Bloch domain wall at the boundary of a stripe domain existing in a ferromagnetic (including ferrimagnetic) film that has information reading means, information writing means, and information storage means and whose easy magnetization direction is perpendicular to the film surface. In a magnetic memory element that uses a vertical Bloch line pair consisting of two adjacent vertical Bloch lines created in the magnetic body as a storage information unit and has means for transferring the vertical Bloch line pair within a Bloch domain wall, the ring in the magnetic material A magnetic memory element characterized in that a ring-shaped stripe domain is retained in a shaped ion-implanted region.