JPS6037548B2 - 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 very 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 vaporized permalloy 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 illusion) substrate 1 by liquid phase epitaxial growth, and a portion 4 other than the pattern 3 of this magnetic thin film 2 is coated with hydrogen, neon, This involves implanting ions such as helium.

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 caused by the rotating magnetic field to move along the green circumference of the pattern 3 as shown 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 made small. High density is achieved. 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 a transfer path where the direction of K of the magnetic thin film bubble crystal and the direction of travel of the transfer path have the relationship shown in Figure 3, and it is generally said that the bias margin of the transfer path is large. This is the path through which bubbles are easily transferred.

Pad track b is a transfer path where the bias margin is said to be the smallest in the relationship shown in FIG. 3, and it is a path to which 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, any path of the continuous disk pattern 3' in the direction K of the magnetic thin film bubble crystal becomes a good track g. This is because the peculiarity of bubble transfer appears due to the magnetocrystalline anisotropy and properties 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 absent, 6-8 is a disk pattern,
3 is a transfer path pattern, and the transfer path pattern 3 is 4.
There is no disk pattern 6-1, and the adjacent disk pattern 6-4 and the adjacent disk patterns 6-5 to 6-8 are lined up with a gap in between. It is assumed that a connected disk pattern is formed.

And these disk patterns 6-1 without, 6-
8 and the magnetic thin film is the disk pattern 6-1.
The lower bubble paths 6-8 are configured as super tracks s, and the upper bubble paths as pad tracks b. 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'
Bubble 7, which is transferred as shown in FIG.
' represents a bubble transferred to super track s.

In addition, Hiroshi, the same ward. represents the easy axis direction of magnetization for 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 per rotation of the 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 together with the rotating magnetic field of the next cycle, but the bubble 5 rotates once and moves around the disk pattern 6-4. Upper passage or pad track b
The disk pattern 6-5 is transferred across the gap to the next disk pattern 6-5 by 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 can cross the gap and move onto the super track s. It has the property of being transferred. 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 a counterclockwise direction to the bubble 7 existing in the upper path of the disk pattern 6-6, that is, the pad track b, the bubble 7 is moved to the adjacent disk pattern 6-5. will be forwarded to.

Then, when the next cycle of rotating magnetic field is applied, 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. will be introduced in Then, as a rotating magnetic field is applied, the bubble 7 is transferred on the super track s and moves to the baffle 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. 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. Transfer gates for writing from a major loop to a minor loop or reading from a minor loop to a major loop in a conventionally known magnetic bubble device having a concatenated disk pattern transfer path can be broadly classified into the following types. It can be divided into two types. The first
In FIG. 5, when the lower transfer path 8 of the major loop is 0 and the super track s is assumed that the information bubble 5 is being transferred from left to right as shown in the figure, the bubble 5 is When reaches a predetermined position, the transfer path 8 of the major loop and the transfer pattern of the minor loop that stores information (
A pulse current is applied to the hairpin-shaped conductor pattern 10 that transfers between the bubble 5 and the transfer path 9, and the bubble 5 is pulled through the hairpin-shaped conductor pattern 10' and transferred to the minor loop transfer pattern 9. be done. That is, information is written to 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 13, and the magnetic field gradient causes the bubble 5 to move from the upper path shell of the major loop transfer path 11 to the minor loop transfer pattern. - The data is transferred and written to the main line 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 the bubble 5 crosses the pad track b of the transfer path 11 of the major loop at the time of logic. The position of the bubble to be transferred is read out to the lower path of the transfer path 14 of the medium loop, ie, the pad track b, via the conductor 15, and there is a disadvantage that the time sequence 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 no major loop 17-1, 17-N represents a minor loop, and 18 and 19 represent conductor patterns, respectively. The lower side of the measure 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
-N has good tracks g on both sides. 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.
The signal is transferred on the speed track s of -1 with the application of a counterclockwise rotating magnetic field.

And the bubble row is a minor loop 17-1 to 17
- When the bubble train is immediately transferred to the corresponding position, when a pulse current is passed through the conductor loop of the conductor pattern 18, the bubble train is introduced into each of the disc patterns of the minor loops 17-1 to 17-N. . In other words, the information bubble is written from the major loop 16-1 to the minor loop 17-1-17-N. Also, when the information bubble comes to the appropriate position of the readout minor loops 17-1 to 17-N, when a pulse current is applied to the conductor loop of the conductor pattern 19, the minor
The bubbles of the loops 17-1 to 17-N are attracted to the corresponding disk pattern of the major loop 16-2, and a bubble train is introduced into the super track s of the major loop 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 17-3, and 18 in the figure correspond to those in FIG. 2 river bubbles, 21 is a disk pattern, 22 and 23 are oval disk patterns forming a transfer path with a predetermined gap, and 24 is a transfer path of the minor loop 17-2. Represents a disk pattern.

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 a major loop 16- as shown in FIG.
1 disc pattern 21 lower super track s
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. The rotating magnetic field HR rotates further and the two bubbles whose directions are oriented in directions A and B do not move along the periphery of the disk pattern 21 as explained in FIG. It is stopped at. When the rotating magnetic field HR rotates and heads in the direction from B to C, it is transferred along the periphery of the elliptical disk pattern 22 with two bubbles and comes to the 20'' position.Furthermore, the rotating magnetic field HR starts one rotation and the ○ As the direction is turned, the bubble 20 is transferred to the position A between the oval disk patterns 22 and 23.
A conductor loop of a hairpin-like conductor pattern 18 is formed between the conductor pattern 1 and the conductor pattern 1.
8 overlaps the transfer disk pattern 24 of the minor loop 17-2 to form 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 other end of the striped magnetic domain 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 directed upward. Even when the flowing pulse current is turned off, the bubble 20' is transferred to the mouth position of the periphery of the transfer disk pattern 24. Next, as the rotating magnetic field HR rotates in directions C and D, the bubble 20 transferred to the minor loop 17-2 moves to this position around the transfer disk pattern 24. By configuring transfer paths at predetermined intervals in the disk pattern configuring the major loop 16-1 in this way, the major loop 16-1
1 to minor loop 17-1 and 17-N, there is no need to cross the major loop pattern itself as in the case shown in FIG. The creation of bubbles in the department is less likely to occur.

And when it comes to modesty, as explained in Figure 7,
Since there is no loop 17-1 and the read bubble from 17-N goes to the super track s below the medium loop 16-2, the time series of writing and reading coincide. In a transfer gate using such crystal anisotropy, as shown in FIG. They are provided individually.

Therefore, there is a drawback that gate resistance increases as the number of minor loops increases. 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 disk pattern areas, the connected disk pattern area is used as a bubble transfer path, and information bubbles are transferred from the bubble transfer path. A major loop and a plurality of minor loops that store the bubbles are configured, and a conductor pattern for writing these bubbles into the core minor loop and the bubbles written in the minor loop are In a magnetic bubble memory element in which a conductor pattern exposed in a major loop is stacked on opposite sides of the major loop and the minor loop with an insulating layer interposed therebetween, the bubble constituting each minor loop The transfer path is formed by arranging two rows of connected disk patterns and connecting them at the end near the writing final gear loop to form a U-shaped arrangement. A hairpin loop is arranged so as to transfer bubbles to the cusp, and a conductor pattern for lowering is arranged so as to transfer bubbles from one end of the U-shaped disk pattern of the minor loop to the major loop. It is characterized by being arranged and formed.

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

An example is shown in FIG.

In the figure, reference numeral 25 indicates a transfer-in gate;
6 is a transfer out gate, 27 is a write closing loop, 28 is a reading closing loop, 29-1 to 29-N are minor loops, and 30 is a transfer out gate.
The in-gate conductor pattern 31 is the transfer-out gate conductor pattern. The disk patterns in each of the minor loops 29-1 to 29-1M are arranged in two rows and connected at the side closer to the write closing jar loop 27 to form a U-shape. The writing finisher loop 27 has a pattern in which two semicircular disks are connected with a gap arranged therebetween, and the gap a
is opposed to the cusp b of the U-shaped connected portion of the minor loops 29-1 to 29-N. Transfer-in-gate conductor pattern 3 is arranged through an insulating layer so that its hairpin loop portion overlaps gap portion a of write closing jar loop 27, and minor loops 29-1 to 29-N The transfer gate is formed separately from the transfer gate. In the transfer out gate 26, a conductor pattern 31 is formed by overlapping the reading major loop 28 and the minor loops 29-1 to 29-N with an insulating layer interposed therebetween. Slit-like notches 31a and 31b are formed in the portions that overlap with the cusp of the closing jar loop 28 and the portions that overlap with the cusps of the closing jar loop 28, respectively.

In this embodiment formed in this way, each minor loop 29
11 to 291N each consist of two rows of patterns, and the bubble transfer path goes around the outside and inside of the U-shaped pattern as shown by the arrow, so the storage capacity per unit area is lower than that of the conventional one. However, the conductor pattern of the transfer gate has only half the number of hairpin loops compared to the conventional one, so the electrical resistance is reduced.

Furthermore, since the bubble transfer utilizes the cusp of the transfer pattern, the residence time of the bubble becomes longer, resulting in an advantage that the operating margin is larger than that of the conventional method. As explained above, in the magnetic bubble memory element of the present invention, the minor loop is formed into a U-shape by connecting two rows of patterns, and the transfer gate is constructed using the cusp. The electrical resistance of the conductor pattern of the transfer gate can be reduced compared to the conventional one, and the operating margin can be increased.

[Brief Description of the Drawings] Fig. 1 is a plan view of a magnetic bubble memory element formed by ion implantation, Fig. 2 is a cross-sectional view taken along the low-n line in Fig. 1, and Fig. 3 is a magnetic thin film bubble crystal direction. FIG. 4 is an explanatory diagram illustrating the relationship between the super track s and the pad track b, and FIGS.
The figure is an explanatory diagram of a transfer gate for a conventional write request in a concatenated disk pattern transfer path, FIG. FIG. 9 is an explanatory diagram of the transfer gate of the magnetic bubble memory element according to the embodiment of the present invention. 25...transfer in gate, 26.
...Transfer out gate, 27, 28...
Major loop, 29-1 to 29-1N...minor loop, 30,31...conductor pattern. Figure 1 Figure 2 Figure 3 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9

Claims (1)

[Claims] 1 Forming an ion implantation layer on the entire surface of the crystal substrate for magnetic bubbles except for a plurality of disk pattern areas, and using the connected disk pattern areas as bubble transfer paths;
A conductor pattern and a minor loop for configuring a major loop for transferring information bubbles from the bubble transfer path and a plurality of minor loops for storing the bubbles, and for writing these bubbles into the minor loops. In a magnetic bubble memory element, a conductor pattern for reading out bubbles written in the major loop into the major loop is laminated with an insulating layer interposed so as to overlap the major loop and the minor loop at opposing positions. , the bubble transfer path constituting the minor loop is formed by arranging the connected disk patterns in two rows and connecting them at the end near the write major loop to form a U-shaped arrangement, and the write conductor pattern is as described above. A hairpin loop is arranged to transfer a bubble to the cusp of the connection part of the major loop, and the read conductor pattern is connected to the major loop from one end of the U-shaped disk pattern of the minor loop. A magnetic bubble memory element characterized in that bubbles are arranged and formed so as to be transferred.