JPS6038788B2 - ion implantation bubble device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION {1} Technical Field of the Invention The present invention relates to a magnetic bubble memory device fabricated by ion implantation.

[2- Background of the Technology Recently, a method has been developed to improve the storage density of magnetic bubble memory devices by forming bubble transfer paths by ion implantation.

This ion implantation bubble device has a thin film 2 of magnetic garnet grown epitaxially in liquid phase on a gadolinium gallium garnet (OGG) substrate 1, as shown in the plan view of FIG. 1 and the cross-sectional view of FIG. Ions such as hydrogen, neon, helium, etc. are implanted into a region 4 other than the pattern 3. In the device in which pattern 3 is formed in this way, the direction of the easy axis of magnetization of region 4 into which ions are implanted coincides with the in-plane direction as shown by arrow a, and the direction of the easy axis of magnetization of pattern 3 remains the same as shown by arrow b. is perpendicular to the in-plane direction of . Therefore, the bubble 5 is transferred along the periphery of the pattern 3 as shown by the arrow c by the rotating magnetic field. Since this pattern 3 has a shape in which circles and squares are arranged in a row so that some of them overlap, the dimensional accuracy can be less strict compared to conventional permalloy patterns that require gaps, so the pattern can be made smaller. High density is achieved. In such an ion-implanted bubble device, when the bubble transfer path has a major-minor configuration, it has conventionally been done to have one minor loop each.
It has not been realized to turn the transfer path into a U-shape.

This is because there is only an inside corner that gently converts 1800 directions as shown in FIG. 3, and with this, it is impossible to achieve a high density of minor loops.
[3] Purpose of the Invention In view of the above-mentioned problems, it is an object of the present invention to provide an ion implantation bubble device having a minor loop in which a transfer path is turned back in a minimum space, for example, by 1800 turns.

t4) Structure of the invention and its object is that, according to the present invention, in an ion-implanted bubble device in which a bubble transfer path is formed by ion implantation into a magnetic bubble crystal, the transfer path that turns back the baffle transfer path has a pattern of turning points. The shape has at least one cusp part, and the inclination around the cusp apex of the side from which the baffle is pulled out from the triangular cusp part is deviated 30 degrees clockwise or counterclockwise from the crystal stripe easy direction. Applicable when rotating the magnetic field in the same direction with an angle in the range of 60 to 110 degrees measured in the same direction from the same direction, and the cusp at the turning point is relative to the adjacent cusp on the entry and exit sides. This is achieved by providing an ion implantation bubble device that always has a peak in the ion non-implanted region so that it is impossible to see straight from the apex of a cusp at a turning point to the apex of an adjacent cusp.

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

First, if we consider connecting two adjacent minor loops at an inside corner of 1800 turns with a cusp on the pad side, the shape with the minimum space will be as shown in Figure 4. However, in this shape, the bubble enters from the direction of A due to the rotating magnetic field counterclockwise to B and reaches D, and then when the rotating magnetic field turns in the direction of 6, the bubble returns to cusp B and ends up at B. It only vibrates between −○. The present invention improves this point. FIG. 5 is a diagram showing the shape of the 1800 folded portion in the transfer path of the ion implantation bubble device according to the present invention.

As shown in FIG. 5, the present invention provides at least one or more cusps 6 between the entrance side (the side where the bubble enters the corner) and the exit side (the side where the bubble exits), and the most concave portion of the cusp 6. The apex is offset from the center line of the cusp in the direction of travel.

This bias was explained by C.C. Shir (IBM) and J.A.P.
This method utilizes the fact that ``the side on which the bubble is drawn from the cusp is closer to perpendicular to the bubble stripe direction, the better the margin can be obtained'' reported in 2388 (1981).Therefore, the present invention In order to obtain this deviation, the center of rotation is the cusp apex of side 7, which pulls out the bubble from cusp part 6, in a direction deviated clockwise or counterclockwise by 30 degrees from the crystal stripe easy direction K (straight line
, X') in the same direction from 60 to 110 degrees. The figure shows the case when measured counterclockwise.
Applied when the rotating magnetic field HR rotates counterclockwise,
When the rotating magnetic field HR rotates clockwise, 8 is 60~
The range shall be 11 people. In addition, the entrance and exit sides adjacent to the cusp 6 of the turning point are designed so that the apex of the cusp 6 at the turning point cannot be seen in a straight line from the apex of the adjacent cusps 8 and 9 (if it is visible, it will be the same as in Figure 4). cusp 8
and 9, mountains 10 and 11 of ion non-implanted regions are formed. Fig. 6 is a diagram obtained by experiment with the relationship between the bias magnetic field HB and the drive magnetic field HR when a is changed in Fig. 5. Curve A is for 8 = 1100, and curve B is for 8 = 900. , curve D shows the case where 8=600, and curve C shows the case where the apex of the cup is placed on the center line of the cup.

It can be seen from the figure that when 8=60 to 1100 of the present invention, the margin is increased compared to the case where the apex of the cusp is located on the center line of the cusp. Figure 7 shows the driving magnetic field H
This is a diagram showing the relationship between 8 and the bias margin ΔHB when R=50, where 8 is 600, that is, the margin width increases as the side that draws out the bubble becomes perpendicular to the stripe easy direction.

Note that when 8 is less than 600, it is difficult to form a pattern in terms of phosphorography technology, and at the same time, it is assumed that the margin will deteriorate because the pattern will deviate from the direction perpendicular to the easy stripe direction. Therefore, the range of 60 to 1100 is appropriate. Fig. 8 shows another embodiment of the present invention, and the difference from the embodiment shown in Fig. 5 is that the corners of the pattern are curved, and the effect is the same as that in Fig. 5. It is similar to '6} Effects of the Invention As explained in detail above, the ion implantation bubble device of the present invention realizes the inside corner of the folded bubble transfer path in a simple shape and in the minimum space, and has major minor problems. This has a great effect in that the structure can be made smaller.

[Brief explanation of drawings]

Fig. 1 is a diagram for explaining the ion implantation bubble device, Fig. 2 is a cross-sectional view taken along the Rolo line in Fig. 1, Fig. 3 is a diagram illustrating the conventional 1800 folded bubble transfer, and Fig. 4 is a diagram for explaining the ion implantation bubble device.
The figure shows the case where the inside corner of the 180° folded bubble transfer path has the minimum space, FIG. 5 shows the shape of the 1800 folded part in the bubble transfer path of the ion implantation bubble device according to the present invention, and FIG. Figure 7 shows the bias magnetic field-drive magnetic field characteristics when changing 8 at the 180° turning point of the bubble transfer path.
The figure shows the bias margin, and FIG. 8 shows another embodiment. Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8

Claims (1)

[Claims] 1. In an ion-implanted bubble device in which a bubble transfer path is formed by ion implantation into a magnetic bubble crystal, the inside corner where the bubble transfer path is folded has at least one cusp portion in the pattern shape of the folding point, and The inclination around the cusp apex of the side that pulls out the bubble from the triangular cusp of the cusp part is 30 degrees clockwise or counterclockwise from the crystal stripe easy direction.
° It is applied when the angle is in the range of 60 to 110 degrees measured in the same direction from the deflection direction, and the magnetic field is rotated in the same direction, and the cusp part at the turning point is the same as the cusp part on the adjacent entry and exit sides. An ion-implanted bubble device characterized in that it always has a peak in the non-ion-implanted region for each part, so that it is impossible to see straight from the vertex of a cusp at a turning point to the vertex of an adjacent cusp.