JPS6329358B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (1) Technical Field of the Invention The present invention relates to an ion implantation bubble device, and particularly to its start/stop direction and hold magnetic field.

(2) Background of the technology Magnetic bubble utilization devices that use magnetic bubbles to store information, perform logical operations, etc. are nonvolatile, high storage density, low power consumption, small and lightweight, and are solid-state devices that do not contain any mechanical elements. It has various characteristics such as.

As shown in Fig. 1, this magnetic bubble memory device is a magnetic bubble memory device in which a magnetic bubble generator, a bubble transfer path, a bubble detector, etc. are formed on a magnetic thin film having uniaxial anisotropy formed on a substrate. It includes a memory element 1, magnets 2 and 3 for generating a bias magnetic field to keep the bubbles generated in the element stable, and coils 4 and 5 for generating a rotating magnetic field to move the bubbles along a transfer path. It is composed of
A magnetic field is applied in the plane of the element (this is called a hold magnetic field) to ensure stop operation and subsequent start operation during magnetic bubble transfer.
is being applied.

(3) Prior Art and Problems In the magnetic bubble memory device as described above, the bubble transfer path has conventionally been formed using a permalloy thin film using a photolithography method. However, recently, due to the demand for higher storage density, the accuracy of permalloy pattern formation has exceeded that of photolithography, and a method of forming bubble transfer paths using ion implantation has been developed.
In this ion implantation bubble device, the technology regarding the start/stop direction and hold magnetic field has not yet been established.

(4) Object of the Invention In view of the above-mentioned conventional problems, an object of the present invention is to provide an ion implantation bubble device in which the start-stop direction and the hold magnetic field are optimally determined.

(5) Structure of the Invention According to the present invention, this object is to form an ion implantation layer on the entire surface of a crystal substrate for magnetic bubbles except for a plurality of disk pattern areas, and to form the connected disk pattern areas. As a bubble transfer path, the major loop formed by the transfer path is in the <101> direction of the crystal substrate, and the minor loop is in the <101> direction of the crystal substrate.
In the ion implantation bubble device formed in each of the <112> directions, the start and stop direction of the bubble is set at 0 degrees with respect to the <112> direction of the crystal, and the hold magnetic field is set to 150e or less. This is achieved by providing

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

FIG. 2 is a diagram for explaining the memory element of the ion-implanted bubble device according to the present invention, in which (a) shows the crystal axis direction, and (b) shows the pattern configuration. In the figure, 6 is a minor loop for storing bubbles, 7 is a major loop for writing to transfer bubbles 11 generated from a bubble generator (not shown) to the corresponding position of the minor loop 6, and 8 is a major loop from the major loop 7 to the minor loop 6. 9 is a reading major loop for transmitting the bubble 12 to a bubble detector (not shown); 10 is a conductor pattern for transmitting the bubble from the minor loop 6 to the major loop 9; Conductor pattern for transfer outgate, H _D indicates rotational drive magnetic field, respectively.

The major loops 7 and 9 for writing and reading are arranged in the <101> direction of the substrate crystal, and the minor loop 6 is arranged in the <112> direction. When a major loop and a minor loop are formed in this way, in the present invention, the start and stop directions are set to 0°, and the hold magnetic field is set to 150e or less.

By setting the above conditions, the bubble stops at the cusp of the minor loop, so a good operating margin can be obtained in the start-stop operation in the minor loop.

FIG. 3 is a diagram showing the relationship between the hold magnetic field H _h and the bias magnetic field H _B , which was obtained as a result of experiments conducted by the inventors. In the same figure, the horizontal axis is the hold magnetic field H _h
The bias magnetic field H _B is plotted on the vertical axis, and curve A shows the start-stop characteristics in the 0° direction, and curves B and B' show the start-stop characteristics in the 180° direction. This experiment was performed using a rotational driving magnetic field for an ion-implanted bubble memory element as shown in Figure 2.
The start-stop characteristics when the bubble is driven by applying 750e of _HDD (the device ambient temperature is approximately 35℃) are as follows:
Hold magnetic field H _h is 9.50e, 6.50e in 180° direction,
3.20e, and H _h = 0, and 1.30e in the 0° direction,
The relationship with the bias magnetic field H _B was investigated for eight types: 3.30e, 40e, and 6.50e. In the case of start-stop at 180° in the figure, the operating margin (region where the bubble between the upper limit curve B and lower limit curve B' stably starts and stops) is constant regardless of the hold magnetic field H _h . However, in this case, the hold magnetic field in the 0° direction is an interfering magnetic field and is not desirable. On the other hand, if you start and stop at 0°,
When a hold magnetic field is applied in the 0° direction, an operating margin (region where the bubble within curve A stably starts and stops) is obtained.

FIG. 4 is a diagram showing the relationship between the hold magnetic field and the minimum drive magnetic field, which was also obtained as a result of experiments by the inventors. In the same figure, the horizontal axis represents the hold magnetic field H _h ,
The minimum driving magnetic field _HD is plotted on the vertical axis, and curve C indicates a start/stop case in the 0° direction, and curve D indicates a start/stop case in the 180° direction. In addition to the above-mentioned eight types of hold magnetic field H _h , the relationship between the minimum drive magnetic field HD _and the case where 80e and 100e were applied in the 0° direction was also investigated. As shown in the figure, the experimental results show that when the hold magnetic field is set in the 0° direction, the minimum drive magnetic field becomes smaller in both the 0° and 180° start/stop directions. When the hold magnetic field is in the 0° direction and the start/stop direction is 180°, the hold magnetic field becomes a disturbing magnetic field. Therefore, by setting the start/stop direction to 0° and setting the hold magnetic field to 100e or less, preferably 2 to 80e, the bias margin can be increased.
Both the minimum driving magnetic field can be improved. The upper limit of the hold magnetic field in the 0° direction was 100e in experiments, but it seems that it can be used sufficiently up to about 150e without the minimum drive magnetic field increasing so much.

Fig. 5 is a diagram showing the operating margin at points a and b in Fig. 4, and the horizontal axis shows the driving magnetic field H _D
The vertical axis shows the bias magnetic field H _B , and the start/stop direction is 0° and the hold magnetic field is expressed by the curve E.
The case of 6.50e (point a in Figure 4) is shown, and the start/stop direction is 180° according to curve F, and the hold magnetic field is
The operating margin for 9.50e (point b in Figure 4) is shown. From the figure, it can be seen that the start-stop direction is better when it is 0°.

(7) Effects of the Invention As explained above in detail, the ion implantation bubble device of the present invention can obtain a good operating margin in start-stop operation by defining the start-stop direction and the hold magnetic field conditions. This has been made possible and has a great effect in contributing to improved reliability.

[Brief explanation of the drawing]

Figure 1 is a diagram for explaining the structure of a conventional magnetic bubble memory device, Figures 2a and b are diagrams for explaining an ion implantation bubble device according to the present invention, and Figure 3 is a diagram for explaining the structure of a conventional magnetic bubble memory device. FIG. 4 is a diagram showing the relationship between the hold magnetic field and the minimum drive magnetic field, and FIG. 5 is a diagram showing the operating margin. In the drawing, 6 indicates a minor loop, 7 indicates a write major loop, 8 indicates a transfer in gate conductor pattern, 9 indicates a read major loop, and 10 indicates a transfer out gate conductor pattern.

Claims (1)

[Claims] 1. 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 a major loop constituted by the transfer path is formed as a crystal substrate. In an ion implantation bubble device in which a minor loop is formed in the <101> direction of the substrate and a minor loop is formed in the <112> direction, the bubble start/stop direction is set at 0° with respect to the <112> direction of the crystal, and the hold magnetic field is set to 15 Oe or less. An ion implantation bubble device characterized by: