JPS6037549B2 - magnetic bubble memory element - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnetic bubble memory device, and more particularly to a transfer gate portion of a magnetic bubble memory device using an ion implantation method.

Magnetic bubble utilization devices that use magnetic bubble memory elements to store information, perform logical operations, etc. have various features such as non-volatile high storage density and low power consumption, and are solid-state devices that do not contain any mechanical elements. Therefore, it has extremely high reliability.

Such magnetic bubble memory devices are also required to have increased storage density due to the recent increase in the amount of information and the demand for smaller devices. However, in the elements used in conventional magnetic bubble memories, the bubble transfer pattern is formed by photo-etching permalloy deposited on a magnetic thin film, so its dimensional accuracy is limited to the accuracy of exposure to visible light, and the pattern is It is becoming difficult to increase the storage density by reducing the size of the memory. For this reason, a method of forming a transfer pattern using ion implantation has recently been developed. 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 bubble crystal, is formed on a gallium garnet (Q°C) substrate 1 by liquid phase epitaxial growth, and a pattern 3 is formed on this magnetic thin film 2.
Ions such as hydrogen, neon, helium, etc. are implanted into the other parts 4.

In the device in which the 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 pattern portion 3 is the same as the original direction as shown by arrow b. It is perpendicular to the same in-plane direction. Therefore, the bubble 5 is moved along the periphery of the pattern 3 by the rotating magnetic field as indicated by the arrow c.
It is transferred as follows. This pattern has a shape in which parts of circles and hexagons are overlapped and arranged in a continuous manner, and unlike the subordinate permalloy pattern, it does not require gaps, so the dimensional accuracy does not need to be loose, so the pattern can be small and high density. will be realized. Further, in the pattern formed by this ion implantation, when a rotating magnetic field is applied to the connected disk pattern 3, the bubbles move along the periphery of the disk pattern 3, as shown in FIG. In addition, such a magnetic thin film has a stripe out pattern, and its axes are in three directions (1), (D), and (m).
), and super tracks s and There are three bubble movement paths: , pad track b, and good track g. Here, super track s refers to the relationship between the K, direction of the magnetic thin film bubble crystal and the traveling direction of the transfer path as shown in Figure 3, and is generally said to have a large bias margin in the transfer path. This is the path through which bubbles are easily transferred.

Pad track b is a transfer path where the bias margin is 4.degree., which is the highest according to the relationship shown in FIG. 3, and is the path where bubbles are difficult to be transferred. Good track g is a path with intermediate operating margin for bubble transfer. As shown in FIG. 3, the path on the opposite side to the super track s becomes a pad track b. Also, the connected disk pattern 3 in the K direction of the magnetic thin film bubble crystal.
′ is a good track g.
This is because the peculiarity of bubble transfer appears due to the magnetocrystalline anisotropy of the magnetic thin film bubble crystal. FIG. 4 is a principle diagram explaining the basic operating principle of a continuous disk pattern transfer path having a super track s and a pad track b, in which 6-1 is not provided, 6-8 is a disk pattern, and 3 is a transfer path. The transfer path pattern 3 includes four disk patterns 6-1, no adjacent disk patterns 6-4, and four disk patterns 6-5.
It is assumed that the adjacent disk patterns of None, 6 and 8 form a connected disk pattern arranged in a row with a gap in between.

And these disk patterns 6-1 to 6-8
The relationship between the disk pattern 6-1 and the magnetic thin film is such that the lower bubble path of the disk pattern 6-1 is a super track s and the upper bubble path is a pad track b. ing. 5 is a bubble that exists in the super track s of the transfer path pattern 3 before the rotating magnetic field is applied, but as the rotating magnetic field is applied, the bubble 5'
Baffle 7 is a bubble that is transferred as shown in FIG.
' represents a bubble transferred to super track s.

Note that the same direction represents the direction of easy magnetization with respect to the disk pattern of a magnetic thin film bubble crystal, such as a garnet film. As shown in FIG. 4, when the bubble 5 exists in the path below the disk pattern 6-1 of the transfer path pattern 3, that is, in the super track s, when a rotating magnetic field is applied in the counterclockwise direction, the bubble 5 is 1 for a mirror that rotates once in a rotating magnetic field.
Bit-by-bit adjacent disk patterns 6-2, 6-3
By repeating this process, bubble 5 is transferred to disk pattern 6-3.

The bubble 5 transferred to the disk pattern 6-3 moves along the periphery of the disk pattern 6-4- with the rotating magnetic field of the next cycle, but the bubble 5 rotates once and transfers to the disk pattern 6-4. It does not rotate to the upper path or pad track b, but is transferred across the gap to the next disk pattern 6-5 by the application of the next rotating magnetic field. In this way, even if there is a gap between the disk patterns, the bubble on the super track s will be transferred on the super track s across the gap if the width is within a predetermined gap. I have a tendency to go. Then, as the rotating magnetic field is applied, the bubble 5 moves and is transferred to the bubble 5'. On the other hand, when a rotating magnetic field is applied in the counterclockwise direction, the bubble 7 existing in the upper path of the disk pattern 6-6, that is, the pad track b, will cause the disk pattern 7 to move toward the adjacent disk patterns 6-5. be transferred.

When a rotating magnetic field is applied in the next period, the bubble 7 is unable to cross the gap and rotates along the periphery of the disk pattern 6-5 as shown by the broken line in FIG. 4, resulting in a super track s. will be introduced in Then, with the application of a rotating magnetic field, the bubble 7 is transferred on the super track s,
Move to bubble 7'. In this way, when there is a predetermined gap between disk patterns in the transfer path pattern 3, the bubble 5 on the super track s is transferred across the gap, whereas the bubble 7 on the pad track b is transferred. It has the property of not being able to cross the gap, but moving along the periphery of the disk pattern and being introduced into the super track s. Writing from the major loop to the minor loop or minor loop of a magnetic bubble device with a concatenated disk pattern transfer path known in the art.

Transfer gates for reading from the main loop to the major loop can be roughly divided into the following two types. The first
In FIG. 5, it is assumed that the information bubble 5 is transferred from the left to the right in the lower transfer path wholesaler s of the major loop transfer path 8 as shown in the figure. When the main loop reaches a predetermined position, a pulse current is applied to the hairpin-shaped conductor pattern 101 that transfers between the transfer path 8 of the major loop and the transfer pattern (transfer path) 9 of the minor loop that stores information. The bubble 5 is pulled by the hairpin conductor pattern 10 and transferred to the minor loop transfer pattern 9. That is, information is written into the minor loop. At this time, the bubble 5 extends across the major loop pattern, in other words the transfer path 8 of the major loop, and is transferred to the minor loop transfer path 9. Nucleation is likely to occur and the bias margin is small. The second transfer gate has the configuration shown in FIG. 6, in which a striped conductor 13 is provided between the transfer path 11 of the major loop and the transfer pattern 12 of the minor loop, and the information bubble 5 is formed. When it reaches a predetermined position, a pulse current is applied to the striped conductor 3, and the magnetic field gradient causes the bubble 5 to be measured.
Data is transferred and written from the upper path of the loop transfer path 11, ie, the super track s, to the minor loop transfer pattern 12. In this transfer gate, the bubble 5 does not need to cross the pad track b of the transfer path 11 of the major loop, but
At the time of reading, the position of the bubble transferred from the minor loop transfer pattern 12 to the major loop transfer path 14 is read out to the lower path, ie, pad track b, of the major loop transfer path 14 via the conductor 15. ,
There is a drawback that the time series of writing and reading is reversed. In response to this, the following transfer gate has been proposed.

To explain this with reference to FIG. 7, 16-1 and 16-2 represent major loops, 17-1 to 17-N represent minor loops, and 18 and 19 represent conductor patterns, respectively. The lower side of the major loop 16-1 is a super track s to which bubbles are easily transferred, and the upper side is formed as a pad track b. The lower side of the major loop 16-2 is a super track s, and the upper side is a pad track b. and minor loop 17-1 to 17
Both sides of 1N are good tracks g. A bubble train corresponding to the address information is generated from a bubble generator (not shown), and the bubble train is passed through the medium loop 16.
-1 super track s with the application of a counterclockwise rotating magnetic field.

And the bubble row is a minor loop 17-1 to 17
1N, when a pulse current is passed through the conductor loop of the conductor pattern 18, the bubble train is introduced into each of the minor loops 17 through 171N disk patterns. Ru. In other words, the information bubble is from the major loop 16-1 to the minor loop 17-
1 and 17-N' will be written. Further, reading is performed when a pulse current is applied to the conductor loop of the conductor pattern 19 when the information bubble comes to the appropriate position of the minor loops 17-1 to 17-N.
The bubbles of the loops 17-1 and 17-N are attracted to the disk patterns of the corresponding measure loops 16-2, and a bubble train is introduced into the super track s of the measure loops 16-2. These bubbles are then transferred along with the rotating magnetic field onto the super track s of the major loop 16-2. FIG. 8 is a principle diagram for explaining the operation of this transfer gate, and is a partially enlarged view of FIG. 7 during writing.

Reference numerals 16-1, 17-1 to 17-N, and 18 in the figure correspond to those in FIG. Two baffles, 21 and 22 are disk patterns forming a transfer path with a predetermined gap, and 24 is a transfer disk pattern of the minor loop 17-2.

Now consider the case where the bubble 20 is stored in the minor loop 17-2.

When the rotating magnetic field HR is directed in the direction C, the bubble 20 of interest is the super track s below the disk pattern 21 of the major loop 16, as shown in FIG.
As the rotating magnetic field HR rotates counterclockwise, the bubble 20 will also move along the periphery of the disk pattern 21, and when the rotating magnetic field HR is approximately in the direction D, the bubble 20 will be located at 20'. transferred to the location. While the rotating magnetic field HR is further rotated and its directions are directed to A and B, the bubble 20 does not move along the periphery of the disk pattern 21 as explained in FIG. 4, but remains at the position 20'. It is stopped. When the rotating magnetic field HR rotates and is directed from B to C, the two bubbles are transferred along the periphery of the disk pattern 21 and come to a position of 20''.
When R starts one rotation and faces in the direction of ◯, the bubble 20 is transferred to position A between disk patterns 21 and 22. A conductor loop of a hairpin conductor pattern 18 is formed between the disk patterns 22 and 23, and the conductor pattern 18 has a minor conductor pattern.
Loop 17-2 transfer disk pattern 2
4 constitutes a transfer gate. When the bubble 20 is transferred to the position A in FIG. 8, a pulse current is applied to the conductor loop of the pin-shaped conductor pattern 18 to weaken the bias magnetic field locally, and the bubble 20 is striped out. The edge of the stripe magnetic domain then reaches the transfer disk pattern 24 of the minor loop 17-2. Eventually, when the direction of the rotating magnetic field HR turns from the direction B to the direction C, a magnetic pole that attracts the bubble 20 is formed in the transfer disk pattern 24, so that the conductor loop of the pin-shaped conductor pattern 18 is formed above. Even when the flowing pulse current is turned off, the bubble 20 remains in the transfer disk pattern 24.
The periphery of the mouth is transferred directly to the oral position. Then, as the rotating magnetic field HR rotates in the direction D, the minor
The bubbles 20 transferred to the disk patterns 17-2 move to positions C and D around the transfer disk pattern 24. In this way, if transfer paths are configured at predetermined intervals in the disk patterns configuring the major loop 16-1, the transfer path from the major loop 16-1 to the minor loop 17-N without the minor loop 17-1 is possible. In this case, it is not necessary to cross the pattern of the measure loop itself as in the case shown in FIG.
・It's small enough.

When lecturing, as explained in Figure 7,
Since there is no loop 17-1 and the issue bubble from 17-N goes to the super track s below the major loop 16-2, the time series of writing and issue coincide.

Such a transfer gate has the above-mentioned advantages, but on the other hand, the minor loops 17-1 to 17-N
Since the shape of the corner transfer pattern is circular or triangular, the residence time of the charged wall is short, and therefore the phase margin for bubble transfer is narrow, and the current bias margin is also small.

The present invention has been devised to improve this drawback. Therefore, in the present invention, an ion implantation layer is formed on the entire surface of the crystal substrate for magnetic bubbles except for a plurality of connected disk pattern areas, and the disk pattern area is used as a bubble transfer path. A major loop that transfers information bubbles by a transfer mechanism and a plurality of minor loops that store the bubbles are configured, and the major loop and the minor loop are placed opposite to each other through an insulating layer so as to overlap with the major loop and the minor loop. In an ion-implanted magnetic bubble memory element in which a write conductor pattern and a logical conductor pattern are stacked to form a transfer gate,
It is characterized by partially removing or flattening the transfer pattern at the corner of the minor loop.

Embodiments of the present invention will be described in detail below based on the accompanying drawings.

FIG. 9 shows a first embodiment.

In the figure, numeral 25 is a medium loop, 26-1 to 26
1N is a minor loop, 27 is a hairpin conductor.
It's a pattern. The major loop 25 is formed by connecting two triangular patterns, and minor loops 26-1 to 26-N are formed opposite the gap b between the major loops 25. The minor loops 26-1 to 26-M are formed in a shape in which rectangular disks are connected, and their tips a have a triangular concave notch in a part of the pattern. Also, conductor pattern 27 has its hairpin part
It is formed to match the gap b of the pattern of the loop 25, and to provide a gap d between it and the tips of the minor loops 26-1 to 26-N. In this embodiment formed in this way, the bubble is connected to the conductor from the medium loop 25.
When transferred to minor loops 26-1 to 26-N by the pattern, minor loops 26-1 to 26
Since the tip a of the 1N is cut out in a concave shape, the time it stays in that part becomes longer.

This widens the phase margin of the transfer and also increases the current bias margin. The size of the notch at the tip a of these minor loops 26-1 to 26-N is as follows:
The bubble may be transferred from c to a to e in one cycle of the rotating magnetic field. FIG. 10 is an embodiment of FIG. 2.

This embodiment differs from the previous embodiment in the minor loop 2.
6-1 to 26-1N have a flat notch shape as shown in the figure. Note that the effects of this embodiment are similar to those of the previous embodiment. In addition, in the first and second embodiments, the shape of the minor loop was a pattern of connected rectangles,
Even if this is a circular connected pattern, its operation and effect are the same as in the embodiment.

As explained above, the magnetic bubble memory element of the present invention is capable of widening its operating margin by devising the shape of the tip of the minor loop in its transfer gate. This contributes to improving memory reliability.

[Brief explanation of drawings]

Figure 1 is a plan view of a magnetic bubble memory element formed by ion implantation, Figure 2 is a cross-sectional view taken along the 0-Ro line in Figure 1, and Figure 3 is a diagram showing the crystal direction and transfer path of a magnetic thin film bubble crystal. FIG. 4 is an explanatory diagram illustrating the basic operating principle of a connected disk pattern transfer path having super tracks s and pad tracks b. FIGS. 5 and 6 are Explanatory diagram of transfer gate for slave write request in pattern transfer path, No. 7
The figure is an explanatory diagram explaining the track of major loop and minor loop bubbles, FIG. 8 is an operation principle diagram explaining the operation of a conventional transfer gate, and FIG. 9 is a first implementation according to the present invention. FIG. 10 is a plan view of the transfer gate of the example magnetic bubble memory element, and FIG. 10 is a plan view of the transfer gate of the second embodiment. 25...Major loop, 261-261N...Minor loop, 27...Conductor pattern. Figure 1 Figure 2 Figure 3 Figure 5 Figure 6 Figure 7 Figure 9 Figure 8 Figure 10

Claims (1)

[Claims] 1. An ion implantation layer is formed on the entire surface of a crystal substrate for magnetic bubbles except for a plurality of continuous disk pattern areas, and the disk pattern area is used as a bubble transfer path, and information bubbles are transferred through the bubble transfer path. A writing conductor pattern and a writing conductor pattern are formed at opposing positions of the major loop and the minor loop through an insulating layer so as to overlap with the major loop and the minor loop. An ion-implanted magnetic bubble memory element in which readout conductor patterns are laminated to form a transfer gate, and the magnetic bubble memory element is characterized in that the transfer pattern at the corner of the minor loop is partially removed or flattened inward. .