JPS61204887A - Magnetic bubble transfer path - Google Patents

Abstract

PURPOSE:To make a stable operation possible by patterning the first transfer path on a magnetic garnet and providing the second auxiliary transfer path on an insulating layer provided on the first transfer path. CONSTITUTION:A transfer path is formed on a wafer where the first insulating layer 8 is formed on a magnetic garnet substrate 7. A 'Permalloy(R)' thin film is formed on the first insulating layer, and this thin film is used to form a transfer path consisting of half disc transfer bits 9. The second insulating layer 13 is formed with about 4,500Angstrom thickness on the first transfer path 12 formed in this manner, and bar patterns 14 are formed on the second layer on the layer 13. Bar patterns 14 are formed on gaps 11 of transfer bits 9 formed in the transfer path of the first layer and are across leg parts 10 of two transfer bits 9. Thus, transfer paths in the two-layered constitution are used to transfer bubbles easily.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is directed to the 3L1 magnetic bubble with an expanded operating margin.
This invention relates to the configuration of a minute magnetic bubble transfer path of I4 μm or less.

With improvements in magnetic garnet and advances in fine pattern formation technology, the storage capacity of magnetic bubble memory per chip gradually increased, dramatically increasing from 64 bits to 256 bits and from 1 Mbit to 4 Mbit. Practical use of bookmarks and such large-capacity memories is progressing.

Here, since the area of the chip is only slightly different from the original 101 square to about 10 x 14 + u of 4M bits, each transfer bit pattern made of a soft magnetic thin film such as permalloy has been made extremely small. For those with a capacity of 4 Mbits, the pattern period has been reduced to about 4 μm, and the pattern gap has been reduced to 0.8 μm or less.
Therefore, as the demagnetizing field coefficient of the soft magnetic thin film increases, the interaction between the magnetic bubbles increases, and as a result, the operating margin of the magnetic bubbles decreases.

[Conventional technology]

Figure 3 shows the shape and arrangement of the bubble transfer path used in large-capacity memory where the storage capacity of one chip exceeds IM bits. Bubbles (hereinafter simply referred to as bubbles) 2 are sequentially transferred from right to left on the paper along a transfer path 3 made of a soft magnetic film such as permalloy, but when the driving magnetic field 1 changes from downward to rightward, bubbles 2 An error 1y is likely to occur when transferring to transfer bit 5, and the limit of the operating margin is determined by this operation.

-゛In particular, when the transfer path 3 is made of permalloy and there are bubbles 2 in each of the adjacent transfer bits 4 and 5 as shown in the figure, the interaction of the bubbles 2 narrows the operating margin, causing the bubbles to disappear. Sit down. 11.
,． 5. As a way to prevent this, for example, a herbatan is inserted in a position where malfunctions are likely to occur, such as a 180 degree curved part of a transfer path consisting of a half-disk transfer bit, to expand the operating margin and improve the characteristics. However, if this method is widely applied, the pattern period becomes long, making it difficult to achieve high density.

In addition, the bubble transfer path has a two-layer structure with an insulating layer in between, and the ends of the transfer bits in the upper and lower layers are alternately overlapped to eliminate gaps between adjacent bits and thereby expand the operating margin. Sometimes.

However, although this method is advantageous in terms of the overlapping dimensions of the ends, it does not contribute much to increasing capacity.

[Problem that the invention seeks to solve]

As shown in Figure 3, the operating margin decreases as the transfer bit pattern that forms the bubble transfer path becomes smaller, but if we try to improve this, the pattern period becomes longer, which goes against the trend of higher density. be.

[Means for solving problems]

The above problem can be solved by forming a transfer path in the first layer, which is made of a soft magnetic film on a magnetic garnet substrate and forming one period, and then forming the transfer path so that it overlaps the gap position of each bit forming the transfer path. This problem can be solved by a magnetic bubble transfer path characterized by forming a second layer bar pattern made of a soft magnetic film through an insulating layer.

[Effect]

The present invention provides a method for improving the operating margin of a bubble without reducing the degree of integration of transfer bits constituting a transfer path. A bar pattern is provided with a part of the bar pattern extending over the transfer bit.

The difference from the two-layer structure transfer path described here as a conventional example is that in the conventional transfer path, bubble transfer is impossible unless either the upper layer or the lower layer transfer path is removed, whereas the structure of the present invention The difference is that the transfer path in the lower layer remains the same as before, so bubble transfer is possible, and the bubble operation margin is improved by providing a transfer path in the upper layer.

Further, while the conventional two-layer structure has transfer bits of the same shape arranged, the upper layer transfer path according to the present invention differs in that bar patterns are arranged.

〔Example〕

Figure 1 shows a half-disk transfer path in which the present invention is implemented.
The same figure (A) is a plan view, and the same figure (B) is a sectional view at the x-x' position.

In other words, the present invention can be applied by adding a first layer onto a magnetic garnet as in the conventional
After patterning a transfer path, a second auxiliary transfer path is provided on an insulating layer provided thereon, and an example will be described below.

As shown in FIG. 1, silicon dioxide (Si0
The first insulating layer 8 consisting of
A transfer path is formed on a wafer formed to a thickness of 0.00 mm.

First, a permalloy thin film of approximately 3,000 layers in thickness is formed on the first insulating layer 8 by a method such as electron beam evaporation, and then photolithography is used to form a permalloy thin film as shown in FIG.
A transfer path consisting of half disk type transfer bits 9 as shown in (B) is then formed.

The width of the leg portion 10 of the half disk type transfer bit 9 is 0.5 to 0.8 μm.

The gap 11 between transfer bits is 0.2 μm, and the repetition period is 2.5 μm.

A second insulating layer 13 is formed to a thickness of approximately 4,500 mm on the first layer transfer path 12 formed in this way, and a second
A bar pattern 14 is formed in each layer.

Here, the second insulating layer 13 is formed by P L
It may be formed by applying a silicon resin such as OS (polyladder organosiloxane) and then heating it, or it may be formed by a CVD method.

Further, the bar pattern 14 was formed under the same conditions as the first layer, and had a width of 1 μm and a thickness of 3000 μm.

Here, the bar pattern 14 is formed over the gap 11 between the transfer bits 9 formed in the first layer transfer path 12, and straddles the legs 10 of the two transfer bits 9.

By using a transfer path with a two-layer structure in this way, bubble transfer becomes easy.

FIG. 2 shows the operating margin, with the horizontal axis representing the drive magnetic field and the vertical axis representing the bias magnetic field.

Here, the solid line 15 indicates the upper and lower limits of the operating margin for the bubble transfer path to which the present invention is applied, while the broken line 16 indicates the upper and lower limits of the conventional transfer path.

As is clear from this figure, by implementing the present invention, the upper limit has been improved and bubble transfer has become easier.

〔Effect of the invention〕

As described above, the bubble operation margin is reduced due to the high density of the bubble transfer path, and malfunctions are likely to occur when bubbles move to adjacent transfer bits. However, by implementing the present invention, stable operation is possible.

[Brief explanation of the drawing]

Figure 1 shows an embodiment of the present invention; Figure (A) is a plan view, Figure (B) is a sectional view, Figure 2 is an explanatory diagram of the operating margin, and Figure 3 is a plan view of a conventional transfer path. , is. In the figure, 2 is a bubble, 3 is a transfer path, 4, . 5.9
is a transfer bit, 8 is a first insulating layer, 10 is a leg portion,
11 is the gap, 12 is the first layer transfer path,
13 is a second insulating layer, and 14 is a pattern. Mine 3senno\7noshi

Claims (1)

[Claims] After forming a first layer transfer path made of a soft magnetic film and forming one period on a magnetic garnet substrate, an insulating layer is formed so as to overlap the gap position of each bit forming the transfer path. A magnetic bubble transfer path characterized by forming a second layer bar pattern made of a soft magnetic film.