JPS6145311B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of manufacturing a magnetic bubble storage device in the form of a continuous disk device, and more particularly to an improvement in the ion implantation process.

BACKGROUND OF THE INVENTION Supported by the remarkable development of electronic technology including semiconductor integrated circuit technology, electronic computers are rapidly becoming smaller and faster. Furthermore, the reliability has been significantly improved by making the circuit elements solid-state. Furthermore, as the use of electronic computers progresses, the storage capacity of storage devices continues to increase year by year, and there is a strong desire to reduce the unit cost and access time required for storage.

In order to reliably store and retain large amounts of information, a highly reliable non-volatile large-capacity memory device is required, but this is impossible to achieve with volatile semiconductor memory; However, magnetic tape devices, magnetic disk devices, and the like have a fatal flaw in that they have moving parts, and it is difficult to say that these are memory devices that meet needs in terms of reliability.

The magnetic bubble was invented in view of the above technical background.

When a bias magnetic field of an appropriate magnitude is applied perpendicularly to the surface of a magnetic thin film such as garnet or orthoferrite having uniaxial magnetic anisotropy, cylindrical magnetic domains, so-called magnetic bubbles, are generated.

A magnetic bubble utilization device that uses these magnetic bubbles to store information, perform logical operations, etc. must be non-volatile, be an all-solid-state element, have a large capacity, and be relatively fast. For these reasons, its practical application is rapidly progressing in fields that take advantage of these characteristics.

This magnetic bubble utilization device requires various functions such as generating, transferring, dividing, enlarging, detecting, and erasing magnetic bubbles. Furthermore, means for applying a bias magnetic field to make the magnetic bubbles stably exist within the magnetic thin film, and means for applying a rotating magnetic field to move the magnetic bubbles within the magnetic thin film are required.

FIG. 1 shows a typical configuration example of a magnetic bubble chip used in a magnetic bubble utilization device.

The illustrated configuration is a so-called major/minor loop configuration, and in the figure, 1 is a major loop, 2 is a minor loop, 3 is a detector, 4 is a generator, 5 is a replicator, 36 is an annihilator, and 7 indicate transfer gates. In the figure, solid lines indicate magnetic bubble transfer paths formed on the magnetic thin plate, and broken lines indicate conductive patterns made of gold or the like also formed on the thin plate.

The operation is performed as follows.

First, the generated magnetic valve generates a magnetic bubble in the loop of the conductor pattern forming the generator 4 by supplying a current in a direction that effectively weakens the bias magnetic field in the loop of the conductor pattern that constitutes the generator 4 according to the information to be written.
The information is transferred over the major loop 1 by a driving magnetic field rotating in the in-plane direction of the magnetic thin film, and the information (for example, one word) is aligned at the opposing position of each minor loop 2. At this time, transfer gate 7
A current is supplied to the conductor pattern constituting the magnetic bubble group on the major loop 1 into each minor loop 2. The magnetic valve sent into each minor loop 2 begins to circulate within the minor loop 2 due to the driving magnetic field, and storage of information is completed.

Next, information is read out when the magnetic bubble group in each minor loop 2 to be read reaches a position facing the transfer gate 7, and the conductor pattern is energized to transfer the information onto the major loop 1. The magnetic pebble train transferred onto the major loop is sequentially transferred by the driving magnetic field and reaches the replicator 5. The plurality unit 5 divides the incoming magnetic bubble into two parts, sends one part to the detector 3 along the permalloy pattern, and sends the other part through the major loop 1 to the minor loop again. The detector 3 is enlarged to increase the detection effect of the magnetic bubbles that arrive one after another, and reads out, for example, a change in the electrical resistance of the magnetoresistive element due to the arrival of the bubbles. If you want to erase the information after reading it and write new information, the divided magnetic bubble is erased by the extinguisher 6 on the Mejjarp, and the new information is written by the generator 4. Write.

FIG. 2 is a block diagram of a package containing the magnetic bubble chip shown in FIG. 1. In the figure, 8
9 is a magnetic bubble chip, 9 is a chip mounting plane,
10 is an XY coil for generating a driving magnetic field, 11 is a ferrite yoke, 12 is a thin plate magnet for applying a bias magnetic field, and 13 is a shield case. Triangular wave currents having a phase shift of 90 DEG as shown in FIG. 3A are applied to each of the XY coils for generating a driving magnetic field to obtain a rectangular rotating magnetic field locus as shown in FIG. 3B. Driving with triangular wave current has various advantages over driving with sine wave current, such as a simple drive circuit, a small number of parts, low drive voltage, and easy integration. There is.

By the way, the above-mentioned magnetic bubble storage devices are classified into the following two types.

The first method is to transfer magnetic bubbles using a permalloy pattern, which has been relatively well researched and is beginning to be put into practical use.

The second method is to conduitively transfer magnetic bubbles.
This is achieved by a magnetized wall (charged wall) generated around a non-magnetic pattern called a disk, and has the advantage that it is easier to increase the density compared to the first type. Research on this type has only recently begun.

The present invention relates to a method of manufacturing a magnetic bubble storage device of the second type, that is, a continuous disk device type, and particularly relates to an ion implantation step, which is one of the steps.

Conventionally, this type of ion implantation proposed uses highly permeable ions such as H ⁺ and He ⁺ , thereby forming a thick and uniform ion implantation layer.

That is, FIG. 4 shows a cross-sectional view a and a plan view b of a chip subjected to such ion implantation.
In the figure, 20 is a GGG substrate, which is a non-magnetic substrate, and 30
31 is a magnetic layer made of a magnetically anisotropic thin film formed on a GGG substrate by liquid phase growth, and 31 is the magnetic layer 30.
A part of the ion implanted part,
40 is a pattern made of gold (Au) for blocking ions and is called a continuous disk, 50 is a moving magnetization wall (charged wall), Bub is a magnetic bubble, and A-A is Fig. 4a.
, H _R is a rotating magnetic field in a plane parallel to the GGG substrate 20 .

As shown in the figure, this contiguous disk device has an ion shielding pattern (contiguous disk) 4 having a bead-like shape.
Ions are implanted into the magnetic layer 30, except for only the portion immediately below the magnetic layer 30, so that the direction of anisotropic magnetization in the portion 31 near the surface lies in the in-plane direction.
The thickness of the ion-implanted portion 31 at this time is approximately 1/3 of the thickness of the entire magnetic layer 30, specifically 3500 Å to 10000 Å. As described above, since the ion implantation portion 31 is thick, ions such as H ⁺ and He ⁺ , which have high permeability, are conventionally used.

In the ion-implanted portion 31 obtained in this way, a magnetization wall is generated in the direction according to the rotating magnetic field H _R , and the magnetic bubble Bub is attracted to this wall and transported.

However, while the above-mentioned H ⁺ and He ⁺ ions have high permeability, they have the disadvantage that the desired effect cannot be obtained unless the amount of ion implantation is increased, and the time required for ion implantation is correspondingly large. are doing.

Specifically, the implantation amount for H ⁺ is 70~
^{He _ _}
In the case of , it is 3.0×10 ¹⁵ pieces/cm ² . in this way,
It is presumed that the larger the ions, the smaller the required implantation amount.

On the other hand, in order to obtain a sufficiently thick ion implantation layer, it is necessary to use highly permeable and therefore small ions.

The present invention was made in view of the above facts, and it is possible to reduce the amount of ion implantation,
The purpose is to obtain a magnetic layer that has sufficient characteristics at the same time.

This purpose is achieved in the present invention in a method for manufacturing a magnetic bubble device in the form of a continuous disk device, in which a first magnetic layer having a bubble magnetic domain on a non-magnetic substrate and having perpendicular magnetic anisotropy is provided. , a second magnetic layer having a smaller magnetic anisotropy in the direction than the first magnetic layer and a material composition different from the first magnetic layer was formed, and an ion shielding pattern of a predetermined shape was formed on the second magnetic layer. This is achieved by subsequently implanting at least Ne ⁺ ions into the exposed second magnetic layer so that the anisotropic magnetization direction of the exposed portion of the second magnetic layer is directed in-plane. One embodiment will be described in detail below with reference to the drawings.

FIG. 5 shows a cross-sectional view a and a plan view b of a chip subjected to ion implantation according to the present invention.

As is clear from comparison with FIG. 4, the ion-implanted layer 35 and the layer 30 containing the magnetic bubbles Bub are made of different composition materials, and other parts are the same as in FIG. 4. .

The ion implantation layer 35 is made of a material that has a smaller magnetic anisotropy in the perpendicular direction than the magnetic bubble holding layer 30 and a larger magnetic anisotropy in the in-plane direction due to ion implantation.

Specifically, the magnetic bubble holding layer 30 is, for example,
It is made of YSmLuCaGeI garnet, and the ion implantation layer 35 is made of YGaYbGaI garnet or the like.

In the present invention, such a two-layer magnetic layer is formed on the GGG substrate 20 by liquid phase growth, and gold (Au) is deposited on the GGG substrate 20.
An ion shielding pattern 40 consisting of the like is arranged, and then Ne is ion-implanted.

As a result, the amount of ion implantation was reduced to 0.5 to 30×10 ₁₄
^{H + ,} He ⁺
Compared to , it becomes 1/100, 1/10.

Moreover, the ion implantation layer 35 has a tendency to respond sharply to ion implantation and direct the anisotropic magnetization direction in-plane, and is sufficient even though Ne ⁺ is used, which does not have high permeability. It is possible to obtain the following characteristics.

That is, FIG. 6 is one of the most important characteristics required of a magnetic bubble storage device.
The operating margin characteristics are shown, and the ion implantation conditions are H ⁺ (75KeV, 39×10 ¹⁶ /cm ² ) and He +
(100KeV, 3.0×10 ¹⁵ /cm ² ), Ne ⁺ (300KeV, 0.6
×10 ¹⁴ /cm ² ) respectively 〇,●,◎
It is expressed in

In FIG. 6, the horizontal axis represents the rotating magnetic field H _R and the vertical axis represents the permissible range (maximum value - minimum value) of the bias magnetic field. As is clear from the figure, even if Ne ⁺ is used, it is possible to provide a magnetic bubble storage device with characteristics that are no better than those of H ⁺ and H ⁺ .

As explained above, according to the present invention, the amount of ion implantation can be reduced to 1/1 of the conventional amount without deteriorating the characteristics.
10, it can be reduced to 1/100. For example, conventional 40mm
It took 4 hours to implant ions into a chip with a diameter of 1/10th or 1/100th of that time.
It can be done with just a few steps, and the effect is enormous.

In addition, in the above description, the in-implantation layer 35 is Y,
Although the present invention has been described as being a GdYbGaI garnet, the present invention is not limited thereto, and the present invention can be similarly applied to any crystal with small uniaxial magnetic anisotropy.

[Brief explanation of the drawing]

1 to 3 are diagrams for general explanation of a magnetic bubble storage device, FIG. 4 is a diagram showing a chip with conventional ion implantation, and FIG. 5 is a diagram showing a chip with ion implantation according to the present invention. The sixth figure is a figure showing the characteristics of the magnetic bubble memory according to the present invention. 20...GGG substrate, 30...magnetic layer, 35...
...Ion implantation layer, 40...Ion shielding pattern, 50...Magnetization wall, Bub...Magnetic bubble.

Claims (1)

[Claims] 1. In a method for manufacturing a magnetic bubble device in the form of a conduitous disk device, a first magnetic layer having a bubble magnetic domain on a non-magnetic substrate and having perpendicular magnetic anisotropy is After forming a second magnetic layer having a smaller magnetic property than the first magnetic layer and having a different material composition from the first magnetic layer, and forming an ion shielding pattern of a predetermined shape on the second magnetic layer, the exposed second magnetic layer is formed. 1. A method of manufacturing a magnetic bubble device, characterized in that ions of at least Ne ⁺ are implanted into a second magnetic layer so that the anisotropic magnetization direction of an exposed portion of the second magnetic layer is directed in-plane.