JPS59127291A - Magnetic bubble memory element - Google Patents

Abstract

PURPOSE:To correct a weak-point part in a transfer pattern and to improve transfer characteristics by positioning at least part of one thin film at least part of where a bubble domain passes through an interpattern gap of the other thin film. CONSTITUTION:A transfer pattern 8 as the 1st layer is formed of ''Permalloy '' simultaneously with a detector pattern and its film thickness is, for example, 500Angstrom . In a figure, 9 is transfer a pattern as the 2nd layer and formed of ''Permalloy'' with, for example, a 3,500Angstrom thickness; and insulating layers 5, 6, and 7 are formed of silicon oxide to, for example, 2,000, 3,000, and 6,000Angstrom and a nonmagnetic conductor thin film pattern 4 consists of 100Angstrom tantalum and 3,000Angstrom gold. In this case, when a bubble domain passes through a 2nd layer interpattern gap, the attacting magnetic field of the 1st layer pattern is formed the 2nd layer interpattern gap parts 44'-45' in addition to a bubble domain attracting magnetic field produced in the 2nd layer patterns according to, for example, directions 14-11 of the rotating magnetic field, so the bubble domain moves through the gap parts relatively smoothly as shown an arrow.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnetic bubble memory device with good transfer characteristics.

Generally, in a bubble device, a puzzle domain created by applying a full bias magnetic field perpendicular to the substrate to a magnetic garnet thin film formed on a gadolinium gallium garnet substrate is transferred onto the thin film using a soft magnetic thin film such as permalloy. A widely used method is to magnetize the entire pattern using a rotating magnetic field within the plane of the substrate and transfer the pattern. Bubble main detection is carried out by sensing the change in magnetic resistance of a detector pattern made of a soft magnetic material such as bubble domain sound enlargement permalloy using a part of the transfer pattern for expansion. Although the detector pattern may be formed of the same thin film as the transfer pattern, it is advantageous in terms of detection efficiency to form the detector pattern with a thinner film.

FIG. 1 shows a cross-sectional view of a conventionally used bubble memory element. 1 is GG on which a magnetic garnet thin film is formed.
It is a G board, 2 is a detector pattern, and 3 is a transfer pattern. A non-magnetic conductive thin film pattern 4 and electrical insulation between each thin film are used to control bubble domain generation, erasure, nine divisions, transition, etc.

Insulating layers 5, 6.7 for protection etc. are formed.

FIG. 3 is a plan view showing an example of a typical transfer pattern that has been used in the past. Here, the direction of the in-plane rotating magnetic field of the substrate is shown in FIG. 4, and assuming that the positive magnetic pole attracts the bubble domains, they move sequentially in the directions of arrows 11 to 14, so the bubble domains 20 also move sequentially in the direction of the arrows. I will be moving. Next, in the rotating magnetic field direction 14-11, the bubble domain moves from 24 to the nearby attractive magnetic field (24'
.

25 minutes). In this way, the bubble domains are transferred sequentially, but in general, the transfer along the pattern is relatively stable along the movement of the attractive magnetic field as described above, but in the case of inter-pattern gears such as 26, the bubble domains are The domain has to jump between places where the attractive magnetic field is discontinuous, which tends to cause malfunctions such as disappearance or jumping out to other cylinder locations, which causes deterioration of operating characteristics.

! Figure @5 is a plan view showing an example of a bubble domain expansion pattern near the detector pattern. In this case, the bubble domains are transferred sequentially in the direction of the arrow in an elongated state as shown in 31, but in the gap between patterns 32 and in the middle part like 33 where the attractive magnetic field is relatively weak, the bubble domains shrink. This has the disadvantage of being easy to use, which causes instability in the detection characteristics.

The present invention provides a bubble memory element that improves the distance m point as described above, and improves the transfer characteristics by correcting the weak point in the conventional transfer turn.

That is, the present invention provides a magnetic bubble memory element having a transfer pattern for bubble domain transfer, wherein the transfer pattern includes a two-layer soft magnetic thin film pattern, and a portion of the gap between the patterns of one of the thin films through which the bubble domain should pass. The magnetic bubble memory element is characterized in that at least one part of the other is located in at least one part of the magnetic bubble memory element. Here, when forming the bubble detection pattern and the transfer pattern separately as in the conventional example shown in FIG.
It is effective to form the transfer pattern of the VC first layer at the same time as forming the detector. In this case, the film thickness of the first layer is appropriate to be 200 to 700λ due to detection efficiency constraints, and the film thickness of the second layer dedicated to transfer is appropriate to be 1500 to 4500A, @1 layer pattern corrects the weak point of the 2nd layer pattern It is effective to use

Hereinafter, an embodiment in which the present invention is applied to a bubble memory element with a domain diameter of 2 μm will be described in detail with reference to the drawings. FIG. 2 shows a cross-sectional view of Example 1°2.3 to which the present invention was applied. The first layer transfer pattern 8 was formed of permalloy at the same time as the detector pattern, and the film thickness was 500A. 9
is the second layer transfer pattern made of 350 OA permalloy, and the insulating layer 5°6.7 is made of silicon oxide and has a thickness of 2000 amp each.
, 3000A.

6000A], and the non-magnetic conductor thin film pattern 4 is tantalum 100 deposited and 300OA, and these have the same structure as the conventional one. In this case, the present invention can be easily implemented since the same manufacturing method as the conventional one may be used.

Figure WJ6 is a plan view showing the first embodiment of the present invention,
The second layer transfer pattern has the same shape as the conventional one and is shown by a solid line. The first layer transfer patterns were arranged as shown by broken lines so as to fill the gaps between the second layer transfer patterns. In this case, when the bubble domain passes through the gap between the two-layer patterns, the second
In addition to the bubble domain attraction magnetic field created by the layer pattern, the first
The attractive magnetic field of the layer pattern is applied to the gap portion 4 between the second layer patterns.
4' to 45', the bubble domain extends relatively smoothly through these parts as shown by the arrow. As described above, in the present invention, the discontinuity of the bubble domain attraction magnetic field is alleviated, and therefore malfunctions such as puzzle domains disappearing or popping out are reduced, and better transfer characteristics than in the past can be obtained.

FIG. 7 is a plan view showing a second embodiment of the present invention. Even in the case of non-example, the second layer pattern has the same Ic shape as the conventional shape.
The first layer pattern has a similar shape to the conventional one.
It was arranged so as to fill the gap between the layer patterns. In the case of this example as well, it was confirmed that the transfer characteristics were improved by correcting the substantial gap between patterns. Normally, the transfer characteristics of a bubble domain are expressed by the size of an allowable range in which transfer between a rotating magnetic field in the plane of the substrate and a bias magnetic field perpendicular to the substrate is normally performed. The permissible bias magnetic field width when bubble domains are packed in each pattern is 200 for conventional rotating magnetic fields of 500e and 600e Ic.
e and 250e, but in the non-inventive Example 1, each increased by about 50e, and it was confirmed that the effect was large.

FIG. 8 shows a third embodiment in which the present invention is applied to a pattern for expanding a bubble domain near a detector.

In this embodiment, not only the gap 51 between patterns in the transfer direction of the bubble domain but also the gap 52 above and below the pattern
Vc also has a first layer pattern indicated by a broken line, and strengthens the bubble domain attraction C1 magnetic field created in response to the rotating magnetic field over the entire pattern.

In this bubble domain extension pattern Vct, the bubble domain attraction magnetic field created in response to the rotating magnetic field over the entire pattern is strengthened, and the phenomenon of shrinkage of the extended bubble domain at the position 51 and 52 is eliminated, and the bubble domain is removed. We were able to obtain more stable detection efficiency than before.

As described above, the magnetic bubble memory element of the present invention can correct the drawbacks of conventional transfer characteristics and obtain good drive characteristics, and can be applied not only to the embodiments but also to a wide range of characteristics improvement. be.

Furthermore, if the first layer pattern is formed at the same time as all the detector patterns, no new process is required and the characteristics can be easily improved, which is very effective. In addition, in the example, a bubble memory element with a domain diameter of 2 μm was used, but in a bubble memory element with a finer domain diameter, the gears and gaps between turns should be adjusted in proportion to the domain diameter due to ftflJ during pattern formation. Since it cannot be made smaller, it becomes increasingly difficult to obtain sufficient transfer characteristics. In such a case, the configuration of the present invention is particularly effective.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view showing a conventional bubble memory device, FIG. 2 is a cross-sectional view of a bubble memory device according to an embodiment of the present invention, and FIG. 3 is a plane view showing a typical transfer pattern shape of a conventional bubble memory device. 4 is a diagram showing the direction of the rotating magnetic field in the plane of the substrate, FIG. 5 is a plan view showing the shape of a transfer pattern bubble domain expander of a conventional bubble memory element, and FIG. FIG. 7 is a plan view showing the shape of the bubble memory element transfer pattern in the embodiment. FIG. 8 is a plan view showing the shape of the bubble memory element transfer pattern in Example i, and FIG. 8 is a plan view showing the shape of the bubble main expander of the bubble memory element in the third embodiment of the present invention. In the figure, 1... GGG board, 2... detector pattern, 3... conventional transfer pattern, 4...
・Non-magnetic 4-body thin film pattern h 5* 6, 7・Old...P
3 Edge layer, 8...First layer transfer pattern of the present invention, 9
...@2-layer rotation pattern of the present invention, 20.21.
・Group/bubble domain, 11-14... Rotating magnetic field direction, 21-24.24', 25° 26.32, 33
．． 43, 44.44', 45°45', 51.52...
...It is ffi. Figure 1 Figure 6 Figure 4 Figure 5 Figure 7 542-

Claims (2)

[Claims] (1) In a magnetic bubble memory element rC having a transfer pattern for bubble domain transfer, the transfer pattern includes a two-layer soft magnetic thin film pattern. A magnetic bubble memory element, wherein at least a portion of the other thin film pattern is located in at least a portion of a portion through which the bubble domain of the interpattern gap of the one thin film should pass. (2) The magnetic bubble memory device according to the above, wherein the transfer pattern is formed simultaneously with the bubble detector pattern and has a thickness of 200 to 700λ.