JPS6149754B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention configures a bubble memory element with two layers of a circular chain-like magnetic material pattern and a bar-shaped magnetic material pattern facing the concave portion thereof, and uses conventional light exposure technology to form a bubble memory element. This invention relates to a magnetic bubble memory device in which bubbles smaller than conventional ones are operated.

Recently, efforts have been made to miniaturize the diameter of magnetic bubbles in connection with higher density bubble memories, but the pattern dimensions are limited by light exposure technology. Figure 1a
is an example of a conventionally frequently used transfer circuit pattern, in which a plurality of half-disk-shaped transfer patterns made of permalloy or the like are arranged on a crystal substrate for magnetic bubbles.

In this case, the minimum limit dimension W is W = 2/3d for the magnetic bubble diameter d. Therefore, if the bubble diameter is set to 1.5 μm or less to achieve high density, the pattern width and gap shown in the figure will be 1 μm or less. Therefore, it cannot be created using conventional light exposure technology.

In order to solve this problem, a new transfer circuit pattern using the ion implantation method shown in FIG. That is, ion implantation is performed by covering a pattern of connected circles with a metal mask, and an ion implantation layer is formed on the surface of the crystal substrate other than this pattern. When the magnetic bubbles are driven with such a configuration by applying a bias and a rotating magnetic field, the magnetic bubbles are transferred along the outer periphery of the connected disk pattern. In this case, the minimum limit dimension of the pattern is the magnetic bubble diameter d
1 to 1.5 times. Therefore, even if the bubble diameter is set to 1.5 μm or less, it is possible to sufficiently create the bubble. Although this method is excellent in principle, it has several unresolved problems in practice.

First, when forming an ion implantation layer on the surface of a crystal substrate, the process becomes complicated because many types of ion implantation are required to obtain good characteristics.

Second, although various proposals have been made for methods of performing switching, division, detection functions, etc. when applied to bubble memory circuits, no practically effective method has been established.

FIG. 2 is a schematic explanatory diagram of the configuration of a conventional magnetic bubble memory device used for writing and reading magnetic bubbles. That is, the magnetic bubble, which is composed of one major loop 1 and a plurality of minor loops 2 by a magnetic material pattern formed on a crystal substrate for magnetic bubbles and corresponds to address and data, is driven by bias and rotating magnetic field applying means,
Write and read.

Therefore, the main loop 1 includes a generator (G) 4, a replicator (R) 5, a detector (D) 3, and a conductor pattern.
An eraser (A) 6 and the like are provided. Magnetic bubbles corresponding to addresses and data generated by the magnetic bubble generator 4 are transferred over the major loop 1, and one piece of information (for example, one word) is arranged at a position facing each minor loop 2. At this time, a current is supplied to the conductor pattern constituting the transfer gate 7 to send the magnetic bubble group on the major loop 1 into each minor loop 2 in parallel. The magnetic bubble sent into each minor loop 2 begins to circulate within the minor loop 2 due to the driving magnetic field and finishes storing information.

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 bubble array transferred onto the medium loop 1 is sequentially transferred by the driving magnetic field and reaches the replicator (D) 5. The replicator 5 splits the incoming magnetic bubble into two, and sends one to the detector 3.
Next, the other one is sent out again to the minor loop 2 via the major loop 1. The detector 3 magnifies the magnetic bubbles that arrive one after another, enters a magnetoresistive element, and reads them out as voltage changes. If it is desired to erase the information after reading and write new information, the eraser 6 is used to erase the information, and the generator 4 writes new information.

A magnetoresistive element detects the change in resistance value that occurs when the magnetization of the element, which is set in the same way as the current, rotates in a direction perpendicular to the current due to the stray magnetic field from the magnetic bubble, as a change in the voltage across the element. be.

Major loop 1 and minor loop 2 as above
However, if the connected disk pattern shown in Fig. 1b is applied, the magnetic bubble diameter can be reduced to 1.5 μm or less, so each loop, especially the minor loop 2
This makes it possible to significantly increase the storage density in . However, there is a simple and reliable method for dividing or switching the magnetic bubble between the major loop 1 and the minor loop 2, for dividing the magnetic bubble transferred onto the major loop 1 by the replicator 5, and for the detection function in the detector 3. Not discovered. The reason for this is that the time it takes to trap magnetic bubbles in the connecting recesses (cusps) of the connecting disk pattern is short and the driving force in this part is weak, making it difficult to reliably stretch or split microbubbles. That's true. In addition, for the detection function after division, it has been proposed to guide the microbubbles to the detector 3 in a large chevron pattern with a strong driving force and to sufficiently enlarge them using the same method as in the past, but this is not possible, as shown in Figure 1. a
Since the patterns of and b are used together, a problem arises in that the range of margin characteristics is different. In any case, since the practicality of the connected disk pattern is still insufficient, it is desirable to use the conventional method to at least increase the density of the minor loop.

An object of the present invention is to provide a magnetic bubble memory device that uses conventional light exposure technology to operate smaller magnetic bubbles than conventional ones.

In order to achieve the above object, the magnetic bubble memory device of the present invention includes a first layer consisting of a circular chain-shaped magnetic material pattern on a magnetic bubble crystal substrate, and a first layer comprising a circular chain-shaped magnetic material pattern in each concave portion. It is characterized by providing a second layer consisting of opposing bar-shaped magnetic material patterns, and further comprising a second layer consisting of opposing bar-shaped magnetic material patterns.
The present invention is characterized in that the circular pattern at the end of the circular chain pattern of the layer is enlarged, and a third layer consisting of a hairpin-shaped conductor pattern facing the circular pattern is provided.

The principle and embodiments of the present invention will be explained in detail below.

To briefly explain the principle of the present invention, the present invention basically uses a conventional method as shown in FIG. 1a. First, we considered transferring magnetic bubbles with a diameter of 1.5 μm or less by forming a circular chain-like pattern similar to that shown in Figure b on a crystal substrate for magnetic bubbles using permalloy.

However, when a driving magnetic field is actually applied, the magnetic bubbles stop at the connecting parts of the circular pattern and do not move. This is because the driving force at the articulation is even weaker than in the case of the articulating disk pattern of FIG. 1b. Therefore, we thought of providing a permalloy bar pattern in the concave part facing the connecting part and driving it using this, but in order to form it on the same surface as the circular pattern, we had to make a gap of 1 μm as shown in Figure 1a.
This is necessary, and as long as this driving force is utilized, the magnetic bubble diameter cannot be reduced to 1.5 μm or less.

On the other hand, in order to make the gap between such magnetic patterns appear zero, the applicant has created two patterns.
It was proposed that it be formed in layers. This makes it possible to eliminate the gap that cannot be eliminated with a single layer in relation to the magnetic bubble. This method is applied to the present invention, and the bar pattern facing the connecting portion is formed in a separate layer so that the apparent gap therebetween is zero.

Of course, it goes without saying that an actual gap exists between both patterns with a spacer interposed therebetween. With this configuration, even magnetic bubbles with a diameter of 1.5 μm or less can be driven by the bar pattern at the connecting part,
Similar to the concatenated disk pattern of FIG. 1b, it can be operated as a high density bubble memory device.

Furthermore, a great advantage of the circular chain pattern of the present invention is that since the entire pattern constitutes a long magnetic material, strong magnetic bubbles are generated in the circular pattern at the ends due to the effects of shape anisotropy and demagnetizing field. Therefore, according to the present invention, it is possible to enlarge the circular pattern at the end and create conditions convenient for stretching the magnetic bubble along the edge and dividing it with the hairpin conductor.

By applying the circular chain pattern having the above-mentioned dividing function to the minor loop shown in FIG. 2, a high-density bubble memory element using microbubbles can be realized. In this case, it may be applied to a medium loop, but since there is no need for high-density packaging, a large pattern with a large pattern period may be used as the transfer circuit in order to transfer magnetic bubbles with a diameter of 1.5 μm or less. It is sufficient to use a conventional detection function with this point in mind.

FIG. 3 is an explanatory diagram showing the configuration of an embodiment of the present invention according to the above-described principle. In the figure, a first layer of circular chain-shaped permalloy patterns 11 is formed on a magnetic bubble crystal substrate, and a second layer of bar-shaped permalloy patterns 13 is provided in the recesses on both sides of the connecting part 12 with spacers interposed therebetween. . The minimum dimensions of the connecting portion 12 and the bar pattern 13 are made to be, for example, about 1 μm, which is possible using light exposure technology. bar pattern 1
Reference numeral 3 applies a driving force to the concave portions on both sides of the connecting portion 12, and the gap between the connecting portion 12 and the bar pattern 13 is apparently zero as described above. This allows stable driving of the minute magnetic bubbles 10 and reliable transfer. With this configuration, a high-density bubble memory element consisting of a first layer of circular chain-like permalloy patterns 11 with a minimum limit size of, for example, 1 μm and a second layer of bar-shaped permalloy patterns 12 can be used for the minor loop 2 in FIG. This enables high-density accumulation.

FIG. 4 is an explanatory diagram showing the configuration of another embodiment of the present invention.

In this figure, only the circular pattern 14 at the end of the high-density bubble memory device of the embodiment of FIG. 3 is made larger than the other chain-like patterns 11.
A third layer hairpin conductor 15 is provided facing the hairpin conductor 15, and a bar pattern 1 is provided on one side of the hairpin conductor 15.
6 constitutes a magnetic bubble divider. That is, since the magnetic bubble 10 transferred to the large circular pattern 14 spreads over a wide range at the tip of the circular pattern 14 due to strong magnetizing force, the pulse current of the hairpin chain 15 causes the magnetic turn 10 to
is split, one is returned to the circular chain pattern 11, and the other is led via the bubble 16 to another transfer circuit.

FIG. 5 shows a cross-sectional view of a magnetic bubble memory device according to an embodiment of the present invention.

In the same figure, a crystal substrate 21 for magnetic bubbles is formed by growing an epitaxial crystal film on a garnet (GGG) surface, performing ion implantation thereon to suppress hard bubbles, and then forming a SiO ₂ spacer 22.
be coated with. On top of that is a hairpin conductor pattern 15.
is provided at the end of the circular chain permalloy pattern 11 at a position opposite to the circular pattern 14, and covered with a SiO ₂ spacer 23. A circular chain permalloy pattern 11 is formed on the top surface, and SiO ₂ spacers 24 are formed.
As described above, the barpermalloy pattern 13 is formed so as to face the concave portions on both sides of each connecting portion 12, and the outer surface thereof is covered with a SiO ₂ protective film 25. In this way, the circular chain permalloy pattern layer and the bar permalloy pattern layer are formed separately so that the gap between the patterns is apparently zero.

As explained above, according to the present invention, a bubble memory element is constructed with two layers of a circular chain-like magnetic material pattern and a bar-shaped magnetic material pattern facing the concave portion thereof, and a bubble memory element is constructed using conventional light exposure technology. It was created using a method that operates a smaller bubble than the conventional one. For example, it is possible to realize a high-density bubble memory device in which the minimum dimension of a pattern, a gap, is made to be about 1 μm, and magnetic bubbles with a diameter of 1.5 μm or less are operated. Furthermore, by utilizing the magnetization characteristics of this circular chain pattern, the circular pattern at the end can be enlarged to obtain a good dividing function, making it possible to apply it to a complete high-density minor loop.

[Brief explanation of the drawing]

1A and 1B are explanatory diagrams of a conventional transfer pattern system, FIG. 2 is a schematic explanatory diagram of a conventional magnetic bubble memory device, FIG. 3 is an explanatory diagram showing the configuration of an embodiment of the present invention, and FIG. 5 is an explanatory diagram showing the configuration of another embodiment of the present invention, and FIG. 5 is a sectional view of the configuration of the embodiment of the present invention. In the figure, 10 is a magnetic bubble, 11 is a circular chain pattern, and 12 is a continuous pattern. 13 is a bar pattern, 14 is an end circular pattern, 15 is a hairpin conductor, and 16 is a bar pattern.

Claims (1)

[Scope of Claims] 1. On a crystal substrate for magnetic bubbles, a first layer consisting of a circular chain-shaped magnetic material pattern, and a bar-shaped magnetic material pattern facing each concave portion of the circular chain-shaped magnetic material pattern. A magnetic bubble memory device comprising a second layer comprising: 2. On a magnetic bubble crystal substrate, a first layer consisting of a circular chain-shaped magnetic substance pattern, and a second layer consisting of a bar-shaped magnetic substance pattern facing each recess of the circular chain-shaped magnetic substance pattern. Further, the circular pattern at the end of the circular chain pattern of the first layer is enlarged, and a third layer consisting of a hairpin-shaped conductor pattern facing the circular pattern is provided. Magnetic bubble memory device.