JPS6040116B2 - Outside turn shape of drive pattern in ion implantation bubble device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION {1' Technical Field of the Invention The present invention relates to an outside turn shape of a drive pattern in a magnetic bubble memory device fabricated by ion implantation.

{2} Background of the technology Magnetic bubble utilization devices that use magnetic bubbles to store information, perform logical operations, etc. have the following advantages: they are nonvolatile, have high storage density, have low power consumption, and are solid-state devices that do not contain any mechanical elements. It has the following characteristics and is expected to have a promising future as a large-capacity memory.

Such magnetic bubble memory devices are also required to have improved storage density due to the recent increase in the amount of information and the demand for smaller devices. For this reason, a method has recently been developed to improve the storage density by forming bubble transfer paths by ion implantation. As shown in the plan view of FIG. 1a and the cross-sectional view of FIG. Then, ions such as hydrogen, neon, helium, etc. are implanted into a portion 4 of the magnetic thin film 2 other than the drive pattern 3.

In the device in which the drive pattern 3 is formed in this way, the direction of the easy axis of magnetization of the ion-implanted portion 4 coincides with the in-plane direction as shown by arrow a, and the direction of the easy axis of magnetization of the drive pattern portion 3 is as shown by arrow B. It is perpendicular to the original in-plane direction. Therefore, by applying a bias magnetic field and a rotary driving magnetic field, the bubble 2 is transferred along the periphery of the driving pattern 3 as shown by the arrow c. This pattern is a shape in which small area patterns consisting of circles, squares, etc. are arranged in a row so that some of them overlap (continuous disk pattern), and does not require gaps like conventional permaloid patterns. Therefore, the dimensional accuracy does not need to be loose, and therefore the pattern can be made small and high density can be achieved. Further, when this driving pattern 3 by ion implantation is used, the bubble naturally moves along the circumference of the driving pattern 3 when a rotating magnetic field is applied as shown in FIG. In addition, such a magnetic thin film has a stripe out pattern, and its axes are in three directions [121], [112], [
211] with 1200 intervals, and these 12
Depending on the relative position shown in the figure of the direction of the drive pattern 3 with respect to the axis of easy magnetization which is spaced by 0o, three bubble movement paths are created: a super track s, a pad track b, and a good track g. {3' Prior art and problems FIGS. 3 to 5 show that when such an ion implantation bubble device has a major-minor loop configuration, the bubble stripes in the difficult direction (opposite to the easy stripe direction) [121 ], [112], [211] direction),
In other words, this is a diagram showing the outside turn shape of a minor loop with a cusp on the super track side. Figures 3 and 4 show a minor loop in which two loops are connected in a U-shape, with a cusp on the outside turn part. Fig. 3 shows a pattern with two diamonds, Fig. 4 shows one with one diamond pattern, and Fig. 5 shows a diamond-shaped pattern with four connected squares.

In each figure, 3 indicates the pattern, a indicates the bubble, arrow b indicates the traveling direction of the bubble, and 6 indicates the crystal axis direction. Conventionally, in any of these types, the distance between the tips is L. was equal to the distance L between the other tips. For this reason, these corner patterns have the disadvantage that when the bias magnetic field is low, an error occurs in which a bubble jumps between tips c to tip d of the adjacent loop. Purpose of the Invention In view of the above-mentioned conventional drawbacks, an object of the present invention is to provide an outside turn shape of a drive pattern in an ion implantation bubble device that avoids the error of bubbles jumping to adjacent loops and expands the lower limit of the operating margin. That is.

■Structure and object of the invention According to the present invention, an ion-implanted layer is formed on the entire surface of the crystal for magnetic bubbles except for the region that becomes the bubble driving pattern, so that a non-ion-implanted small region pattern can be formed. In an ion implantation bubble device in which a bubble transfer path is a driving pattern in which the driving patterns are connected, at least one of the small area patterns formed at the end of the driving pattern on the [121], [211], or [112] side is adjacent to To provide an outside turn shape of a drive pattern in an ion implantation bubble device, characterized in that the height of the tip is formed to be lower by at least the diameter of the bubble so that the distance between the tip and the drive pattern is increased. achieved by

Embodiment of '6' invention Embodiments of the present invention will be described in detail below with reference to the drawings.

6 to 8 are diagrams for explaining the outside turn shape of the drive pattern in the ion implantation bubble device according to the present invention, and FIGS. 6 and 7 show the two drive patterns in a U-shape. FIG. 6 shows a connected minor loop drive pattern with two cubs in the outside turn portion, FIG. 7 shows one with one cusp, and FIG. 8 shows a diamond mode pattern with connected quadrangles. In each figure,
Reference numeral 7 indicates a U-shaped minor loop drive pattern, a indicates a cusp, arrow b indicates a bubble traveling direction, 8 indicates a small area pattern of the drive pattern 7, and 9 indicates a crystal axis direction. In this embodiment, [121
] side (the same applies to the [211] or [112] side), the tips c and d are arranged so that the distance L between the tips is large between the pattern 8 formed at the end of the [211] or [112] side. The height is made lower by at least the bubble diameter.

Note that it is also possible to leave L as it is and lower only either tap c or tap d. In this embodiment formed in this manner, the distance between the tips at the tips of the corner portions is large, so errors caused by bubble jumping are reduced, and the lower limit of the bias margin is expanded.

FIG. 9 is a diagram comparing the bias margins of the embodiment of the present invention and the conventional example. In the same figure, the driving magnetic field is plotted on the machine axis, and the bias magnetic field is plotted on the vertical axis. Curve A shows the characteristics of this embodiment, and curve B shows the characteristics of the subordinate example. In the case of this embodiment, the shape is shown in FIG. 6, and P=201 m, L. =5Am, L=L. 13 Buddhas m = 8 mountains m, and the conventional example is P = 20rm, L = L, =
This is the case when it is 5 m. It can be seen from the figure that the lower limit of the margin and the minimum driving magnetic field have been improved.

'7 - Effects of the Invention As explained in detail above, the outside turn shape of the drive pattern in the ion implantation bubble device of the present invention reduces the bubble flow to the adjacent drive patterns by narrowing the small region pattern at the tip. This is highly effective in preventing jump errors, increasing the lower limit of the bias margin, and reducing the minimum drive magnetic field.

[Brief explanation of the drawing]

Figure 1 is a diagram for explaining an ion implantation bubble device, Figure 2 is a diagram for explaining the relationship between its crystal direction and transfer path, and Figures 3 to 5 are for conventional ion implantation bubble devices. A diagram to explain the outside sunset shape,
Figures 6 to 8 are diagrams for explaining the outside turn shape for an ion implantation bubble device according to the present invention, and Figure 9 compares the bias margin of the outside turn for an ion implantation bubble device according to the present invention with a conventional example. FIG. In the drawings, 7 indicates a driving pattern, 8 indicates a small area pattern, 9 indicates a crystal axis direction, and arrow b indicates a bubble transfer direction. Figure 1 Figure 2 Figure 5 Figure 3 Figure 4 Figure 6 Figure 7 Figure 8 Figure 9

Claims (1)

[Claims] 1. An ion-implanted layer is formed on the entire surface of a ceramic bubble crystal except for a region that becomes a bubble drive pattern, and a drive pattern in which non-sulfur-implanted small region patterns are connected is formed into a bubble. In the ion implantation bubble device used as a transfer path, at least one of the small area patterns formed at the end of the drive pattern on the [121], [211], or [112] side has a taper with the adjacent drive pattern. An outside turn shape of a drive pattern in an ion implantation bubble device, characterized in that the height of the tape is formed to be lower by at least the diameter of the bubble so that the distance between the tapes is increased. 2. The outside turn shape of the drive pattern in the ion implantation bubble device according to claim 1, wherein the drive pattern is a pattern forming a minor loop.