JPH02304794A - Magnetic bubble memory device - Google Patents

Abstract

PURPOSE:To enlarge a common bias magnetic field operating area and to obtain the stable transfer characteristic of magnetic bubble by employing an asymmetrizing means into an ion injection transfer path. CONSTITUTION:The asymmetrizing means is provided to relieve difference between the right and left bias magnetic field margins of a magnetic bubble transfer path and preferably, as the asymmetrizing means, a cross angle is provided between the triaxially symmetric crystal shaft direction of a magnetic bubble magnetic film, to which ion is injected, and a magnetic bubble transfer direction. The means to asymmetrize the transfer path is a parameter to strong ly affect the bubble transfer of the ion injection transfer path and an unbalanced state of the right and left bias magnetic field margins of the transfer path can be reduced. Thus, the common bias magnetic field operating area can be enlarged and the stable transfer characteristic can be obtained.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a magnetic bubble memory device, and particularly to a magnetic bubble memory device having a transfer path using an ion implantation method. [Conventional technology]

By using an ion implantation type transfer path pattern instead of the conventional permalloy thin film pattern for the magnetic bubble transfer path, which is a basic component of a magnetic bubble memory device, a highly integrated device can be realized. The transfer path of the ion implantation method has a structure as illustrated in FIG. In the figure, reference numeral 1 denotes a magnetic film that is a medium for magnetic bubbles, and a magnetic bubble B exists within this magnetic film. By selectively implanting ions such as H, ", He", Ne+, etc. into the surface of this magnetic film, the magnetic bubble transfer path 1
form 0. The outer region 20 of No. 10 is an implanted region into which ions are implanted, and the inner region thereof is a non-ion implanted region into which ions are not implanted. magnetic bubble B
is transferred along the boundary between this non-ion implantation region pattern (magnetic bubble transfer path 10) and the ion implantation region 20 at its periphery. That is, by applying a bias magnetic field Hs from the outside in a direction perpendicular to this film, the magnetic bubble B is made to exist stably. Transfer of the magnetic bubble is performed by applying a rotating magnetic field HH rotating within the film surface from the outside. The ion implantation region 20 is
By magnetizing the bubbles and generating bubble attracting magnetic poles at the boundaries of the magnetic bubble transfer path 10, the bubbles are transferred to the magnetic bubble transfer path 1.
Transfer along the 0 boundary. When the rotating magnetic field HR rotates counterclockwise, the direction of bubble transfer is in the direction of arrow P, which is opposite on the left and right sides of the magnetic bubble transfer path 10. In a magnetic bubble memory device, a large number of magnetic bubble transfer paths 1o in FIG. 6 are formed in parallel and used as a minor loop m for storing and accumulating information. In an actual device, a major line M forming an information input/output path is formed outside of this minor loop m in a direction perpendicular to the minor loop m. In FIG. 6, furthermore. The magnetic bubble magnetic film 1 is made of a garnet magnetic film and has a three-axis symmetrical crystal axis orientation, and the bubble transfer direction axis A of the minor loop m is aligned with the crystal axis orientation [1Ryo2] or [Ryo2Ryoco]. Or, it has been conventionally done to match [21 End]. Magnetic bubble memory devices equipped with such ion implantation transfer paths are already known, and an example of this type is disclosed in Japanese Patent Application Laid-Open No. 60-226089.

[Problem to be solved by the invention]

Now, in order to put into practical use a magnetic bubble memory device equipped with such an ion implantation transfer path, it is necessary to realize an ion implantation transfer path that can stably transfer the magnetic bubbles B along the ion implantation transfer path 10. There is. For this reason, in the past, optimization studies have been conducted by changing the ion implantation process conditions, such as the amount of ion implantation, acceleration voltage, type of ions, stabilizing beta temperature, etc., as well as the shape of the transfer path pattern. It's here. As a result, relatively stable transfer characteristics are obtained for the left and right sides of the bubble transfer path 10 in FIG. 6, respectively. However, as illustrated in FIG. 5, the bias magnetic field margin area ΔHa for stable operation of the left and right transfer paths causes a large imbalance between the left and right sides, and the common margin area becomes narrow. This unbalance amount is on the low temperature side (0℃→-40℃)
°C), it becomes extremely bad, and the common margin area is halved. As a result, stable transfer characteristics sufficient for practical use cannot be obtained using these parameters alone. Therefore, an object of the present invention is to solve such conventional problems, and to provide improved transfer that reduces the unbalance between the left and right transfer path characteristics, expands the common bias magnetic field operating region, and provides stable transfer characteristics. An object of the present invention is to provide a magnetic bubble memory device with a magnetic bubble channel.

[Means to solve the problem]

As a means for achieving the above object of the present invention, the present invention is characterized in that, in order to improve the transfer path characteristics, asymmetrical means is introduced into the left and right transfer paths, which were conventionally symmetrical. That is, the object of the present invention is as follows: (1) In a magnetic bubble memory device equipped with a magnetic bubble transfer path using an ion implantation method, the bias magnetic field margin in the left and right opposite transfer directions in the magnetic bubble transfer path is improved. This is achieved by a magnetic bubble memory device that is provided with an asymmetrical means for alleviating the difference in bias magnetic field margins on the left and right sides of the magnetic bubble transfer path, as a means for reducing the imbalance in transfer characteristics based on the difference. Preferably, (2), as the asymmetrical means, an intersecting angle is provided between the three-axis symmetrical crystal axis orientation of the ion-implanted magnetic bubble magnetic film and the magnetic bubble transfer direction (1). More preferably, in the magnetic bubble memory device described above, (3), the magnetic bubble transfer path is composed of a major line for information input/output and a minor loop for information storage, and the magnetic bubble transfer path is formed of the three-axis symmetric magnetic bubble magnetic film Also, by the magnetic bubble memory device according to (2) above, in which the crystal axis is shifted by 2 to 15 degrees with respect to the bubble transfer direction axis of the minor loop. (4) As the above-mentioned asymmetrical means, the shape of the magnetic bubble transfer path pattern is formed by an ion implantation method. The above (1) is made asymmetrical with respect to the magnetic bubble transfer direction.
), and preferably (5) the shape of the magnetic bubble transfer path pattern. By the magnetic bubble memory device described in (4) above, which has a sawtooth shape, and (6), the ion implantation transfer path is formed between an implanted region where ions are implanted into the surface of the magnetic substrate and a non-ion implanted region where ions are not implanted. As the asymmetrical means, a first magnetic thin film pattern is provided in the non-ion implanted region, and at least in the vicinity of the recess around the transfer path pattern on the implanted region where the ions are implanted. is achieved by the magnetic bubble memory device described in (1) above, in which the second magnetic thin film pattern is formed adjacently. Furthermore, in the present invention, the above (2), (4), (
It is also effective to combine at least two of 6).

[Effect]

The ion implantation transfer path utilizes the magnetic stress effect created by mechanical stress and strain. By making the transfer path asymmetrical in order to expand the common bias magnetic field operating region, it is possible to reduce the imbalance between the bias magnetic field margins on the left and right sides of the transfer path. As mentioned above, there are basically three methods (2), (4), and (6) as specific methods for making this transfer path asymmetrical, and all have similar effects. Therefore, it is also possible to combine two or three of these methods. This means of making the transfer path asymmetric is a parameter that has a strong magnetic effect on bubble transfer in the ion implantation transfer path, and is effective in reducing the imbalance between the bias magnetic field margins on the left and right sides of the transfer path. do.

[Embodiment 1] An embodiment of the present invention will be described below with reference to the drawings. Example 1 Figures 1 (a) and (b) show the results of the present invention when the three-axis symmetrical crystal axis direction is shifted from the bubble transfer direction axis A of the minor loop m by an intersection angle θ to make it asymmetric. FIG. 2 is an explanatory diagram showing a plan view of a main part of a transfer path according to an embodiment. First, in FIG. 1(a), 1 is a magnetic film that is a medium for magnetic bubbles, 1 is a magnetic garnet film formed on a non-magnetic garnet substrate (not shown) by a well-known method, and 20 is a magnetic film that is a medium for magnetic bubbles.
H2'', He'' on the surface of the magnetic film. The region 10 in which ions such as Ne'' are selectively implanted is a transfer path constituting a minor loop m, and the inner region is a non-ion implantation region where ions are not implanted. FIG. 2 is a diagram illustrating the relationship between the bubble transfer direction axis A of the minor loop m and the crystal axis orientation of the three-axis symmetrical magnetic film 1. ] or [21 completed] and the transfer direction axis A of the bubble transfer path 10 is θ. Conventionally, θ=0'' is selected, and the left and right transfer paths of the bubble transfer path 10 are It had a symmetrical configuration. On the other hand, in the present invention, a crossing angle θ is provided, preferably a crossing angle of θ=2 to 15°. Figure 2 is a characteristic curve showing an example of the experimental results of this intersection angle θ and the unbalance loss amount ΔL of the left and right transfer paths described in Figure 5. The smaller the loss amount ΔL, the better the characteristics. As is clear from Figure 1, the intersection angle θ=±(2 to 15
Excellent properties were obtained within the range 6). Embodiment 2 FIGS. 3(a), (b), and (c) each show a transfer path pattern in which the shape of the transfer path pattern is made asymmetric with respect to the bubble transfer direction, which is another embodiment of the present invention. It shows a plan view. Figure (a) shows an example of asymmetrical upward and downward directions;
b) is an example that is asymmetrical in the left-right direction, and similarly (c
) shows an example of a sawtooth pattern. In either case, the unbalance loss amount ΔL was able to be halved compared to the conventional symmetrical pattern. Embodiment 3 FIG. 4 shows an example of another embodiment according to the present invention, in which the first soft magnetic thin film pattern 40 is placed in the non-ion implantation region of the transfer path 10, and the second soft magnetic thin film pattern 40 is 2 is a plan view of an asymmetric transfer path pattern in which a thin film pattern 50 is provided adjacent to the concave portion around the transfer path 10. FIG. Normally, this soft magnetic thin film pattern can be formed in the same place and in the same process as the magnetic thin film pattern forming the bubble detector, for example. Permalloy thin films are often used as this magnetic thin film pattern. By utilizing the magnetic field generated by this pattern, bubble transfer is assisted. In other words, the first soft magnetic thin film pattern 40 described above is an auxiliary pattern that strengthens the driving force for bubble transfer, and the second soft magnetic thin film pattern 50 is a pattern provided between adjacent transfer paths that allows bubbles to be transferred. This is an auxiliary pattern introduced to prevent so-called transfer malfunctions in which a transfer path jumps to an adjacent transfer path. By introducing these patterns, the unbalance loss amount ΔL on the left and right sides of the transfer path could be halved as in the second embodiment. Note that in this embodiment, the second soft magnetic thin film pattern 5
0 is provided as an independent hexagonal pattern between two adjacent transfer paths as shown in the figure, but it is also possible to have a pattern shape in which adjacent patterns 50 are connected to each other instead of being provided as independent patterns. In addition, in the present invention, the above-mentioned Examples 1 to
It goes without saying that it is also possible to implement the transfer path asymmetrical means shown in 3 in combination. Effects of the Invention As detailed above, according to the present invention, by introducing an asymmetry means into the ion implantation transfer path, the imbalance between the left and right transfer path characteristics that occurs during bubble transfer can be reduced, and the common bias magnetic field can be reduced. The operating range (commonly known as bias margin) can be expanded, and stable magnetic bubble transfer characteristics sufficient for practical use can be obtained, making it possible to put magnetic bubble memory devices with ion implantation transfer paths into practical use. And so.

[Brief explanation of drawings]

FIG. 1 shows an embodiment of the present invention; FIG. The figure is a characteristic curve diagram showing the relationship between the crossing angle θ in FIG. 1(b) and the unbalance loss amount ΔL (%) of the left and right transfer paths, and FIG. 3 shows another embodiment of the present invention. FIG. 4 is a plan view of a transfer path pattern in which the shape of the transfer path of the ion implantation path is made asymmetric, and FIG. FIG. 5 is a plan view of the asymmetric transfer path pattern, and FIG. 5 is an explanatory diagram showing the difference in the bias magnetic field margins on the left and right sides of the transfer path and how the common margin changes with temperature, and FIG. 6 is a diagram of the conventional magnetic bubble memory device. FIG. 2 is a partially cross-sectional perspective view of an ion implantation transfer path in FIG. 1... Magnetic film, 10... Ion implantation transfer path 2
0... Ion implantation region, 40... First soft magnetic thin film pattern, 50... Second soft magnetic thin film pattern, A... Bubble transfer direction axis of transfer path, B.
...Magnetic bubble y HB...Bias magnetic field +HR・
...Rotating magnetic field, P...Magnetic bubble transfer direction.

Claims (1)

[Claims] 1. In a magnetic bubble memory device equipped with a magnetic bubble transfer path using an ion implantation method, transfer based on a difference in bias magnetic field margins in opposite transfer directions on the left and right sides of the magnetic bubble transfer path. A magnetic bubble memory device comprising, as a means for reducing characteristic imbalance, an asymmetry means for alleviating the difference between the bias magnetic field margins on the left and right sides of the magnetic bubble transfer path. 2. The magnetic bubble memory device according to claim 1, wherein the asymmetrical means comprises providing an intersection angle between the three-axis symmetrical crystal axis orientation of the magnetic bubble magnetic film into which ions are implanted and the magnetic bubble transfer direction. 3. The magnetic bubble transfer path is composed of a major line for information input/output and a minor loop for information storage, and the crystal axis of the 3-axis symmetrical magnetic bubble magnetic film is aligned with the bubble transfer direction axis of the minor loop. 3. The magnetic bubble memory device according to claim 2, wherein the magnetic bubble memory device is shifted by 2 to 15 degrees. 4. The magnetic bubble memory device according to claim 1, wherein the asymmetrical means makes the shape of the magnetic bubble transfer path pattern formed by ion implantation asymmetrical with respect to the magnetic bubble transfer direction. 5. The magnetic bubble memory device according to claim 4, wherein the magnetic bubble transfer path pattern has a sawtooth shape. 6. The ion implantation transfer path is composed of an interface between an implanted region where ions are implanted into the surface of the magnetic substrate and a non-ion implanted region where ions are not implanted. 2. A magnetic thin film pattern according to claim 1, wherein a first magnetic thin film pattern is formed, and a second magnetic thin film pattern is formed adjacently at least in the vicinity of the recess around the transfer path pattern on the implanted region where the ions are implanted. Magnetic bubble memory device.