JPS635837B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (1) Technical Field of the Invention The present invention relates to a transfer pattern for a magnetic bubble memory device created by ion implantation.

(2) Background of the technology Magnetic bubble utilization devices that use magnetic bubbles to store information, perform logical operations, etc. have various features such as non-volatile high storage density and low power consumption, and furthermore, they do not require any mechanical elements. Since it is a solid-state device that does not contain any The recent increase in the amount of information in such magnetic bubble memory devices
There is a demand for increased storage density due to demands for smaller devices. For this reason, recently, a method has been developed to form bubble transfer paths by ion implantation to improve storage density. This method uses gadolinium as shown in the plan view in Figure 1 and the cross-sectional view in Figure 2.
A thin film 2 of magnetic garnet, which will become a crystal for bubbles, is formed on a gallium garnet substrate 1 by liquid phase epitaxial growth, and ions of hydrogen, neon, helium, etc. It is injected with. In the element in which the pattern 3 is formed in this way, the direction of the easy axis of magnetization of the ion-implanted part 4 coincides with the in-plane direction as shown by arrow a, and the direction of the easy axis of magnetization of pattern part 3 is the same as the original direction as shown by arrow b. It is perpendicular to the in-plane direction. Therefore, the bubble 5 is transferred along the periphery of the pattern 3 as shown by the arrow c by the rotating magnetic field. This pattern has a shape in which circles and squares are arranged in a row so that some of them overlap, and unlike conventional permalloy patterns, it does not require a gap, so the dimensional accuracy can be loose, and the pattern is small. This results in higher density.

The magnetic thin film patterned by this ion implantation method has axes that are easily striped out at 120° intervals in three directions (), (), and (), as shown in Figure 3. Depending on in which direction the connected disk patterns 3 are lined up in a line with respect to the axis of easy magnetization which forms the interval , there are three bubble movement paths: super track s, butt track b, and good track g.

(3) Prior Art and Problems FIG. 4 is a diagram showing an example of a bubble transfer pattern of a conventional ion implantation bubble device. In the figure, numeral 6 indicates a transfer pattern formed in a U-shaped folded portion where ions are not implanted, and numeral 7 indicates an ion implantation region.

As shown in Figure 4, when conventionally designing a pair of positive and negative corners on the super side or butt side of a minor loop, the area of the non-ion implanted region inevitably becomes large due to restrictions on the geometric pattern shape. Parts A and B are generated. In such a case, bubble 8 transferred from the direction of arrow P is
A malfunction such as moving from a point to the R point of an adjacent pattern may occur.

(4) Object of the Invention In view of the above-mentioned conventional problems, it is an object of the present invention to provide a transfer pattern that is less likely to cause malfunctions in an ion implantation bubble device.

(5) Structure of the Invention According to the present invention, the object is to reduce the area of the non-ion-implanted region in the bubble transfer path of an ion-implanted bubble device in which a bubble transfer path is formed in a magnetic bubble crystal by ion implantation. This is achieved by providing a transfer pattern for an ion-implanted bubble device, which is characterized in that a hole for an ion-implanted region is provided in a wide portion in addition to a transfer path.

(6) Examples of the invention Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 5 is a diagram showing a transfer pattern for an ion implantation bubble device according to the present invention. The figure shows the case where the application is applied to a pair of super-side positive corners and butt-side reverse corners on the 121 side (211 or 112 are equivalent directions) of the crystal, and 10 is a non-ion implanted region (hatched). 11 indicates the ion implantation region (the part without hatching).

In the transfer pattern 10 according to the present invention, holes 12 and 13 for ion implantation regions are provided in the large area of the non-ion implantation region.

FIG. 6 is a diagram showing a bias margin of a positive corner of a transfer pattern according to the present invention in comparison with a conventional example. In this figure, the vertical axis represents the bias magnetic field, and the horizontal axis represents the driving magnetic field. Curves A and A' represent the case according to the present invention, and curves B and B' represent the conventional characteristics.

From the figure, the lower limit in the case of the present invention (indicated by curve A')
It can be seen that this is improved by about 60e compared to the conventional model (shown by curve B'). This is because the lower limit malfunction mode is a malfunction in which the bubble 8 coming from the direction of arrow P moves to the adjacent loop as shown in FIG.
This is because it is improved by providing 3.

(7) Effects of the Invention As explained in detail above, the transfer pattern for an ion-implanted bubble device of the present invention prevents malfunction by providing a hole in the ion-implanted region in a wide part of the non-ion-implanted region. This has a significant effect in that it contributes to improving the reliability of ion-implanted bubble devices.

[Brief explanation of the drawing]

Fig. 1 is a plan view of a magnetic bubble memo element formed by ion implantation, and Fig. 2 is a - of Fig. 1.
3 is a diagram for explaining the relationship between the crystal direction of a magnetic thin film bubble crystal and a transfer path, and FIG. 4 is a diagram showing an example of a bubble transfer pattern of a conventional ion implantation bubble device. FIG. 5 is a diagram showing a transfer pattern for an ion implantation bubble device according to the present invention, and FIG. 6 is a diagram showing the characteristics of the transfer pattern according to the present invention in comparison with a conventional transfer pattern. In the drawing, reference numeral 10 indicates a transfer pattern, reference numeral 11 indicates an ion implantation region, and reference numerals 12 and 13 indicate holes in the ion implantation region.

Claims (1)

[Claims] 1 In the bubble transfer path of an ion-implanted bubble device in which a bubble transfer path is formed in a magnetic valve crystal by ion implantation, a hole for the ion implantation region is provided separately from the transfer path in a large area of the non-ion implanted region. A transfer pattern for an ion implantation bubble device characterized by: