JPS6369090A - Magnetic bubble memory element - Google Patents

Abstract

PURPOSE:To obtain a stable bubble transfer characteristic by allowing the pattern curvature of the part to transfer a bubble from a cusp part on the transfer pattern of an ion implantation transfer path to a step part larger than the pattern curvature from the step part to the cusp part. CONSTITUTION:For the transfer pattern IPT of an ion implantation transfer path I, the pattern curvature of a transfer part P0 from the cusp part C to a step part T is formed larger than the pattern curvature of a transfer part P1 from the step part T to the cusp part C along a transfer direction P of the bubble. When the pattern curvature of the transfer part P0 is larger, the sufficient driving force to pull out the bubble from the cusp part C is given. Wheares, since the small driving force is sufficient at the transfer part P1, it is unnecessary to enlarge the pattern curvature so much. Consequently, the stable bubble transfer characteristic can be obtained by the pattern shape.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a magnetic bubble memory element having an ion implantation transfer path, and particularly to the configuration of the transfer path.

[Conventional technology]

The transfer path of the magnetic bubble memory element includes a permalloy transfer path that transfers magnetic bubbles by magnetizing a permalloy thin film pattern with a rotating magnetic field that rotates within the pattern plane, and a permalloy transfer path that transfers magnetic bubbles by magnetizing a permalloy thin film pattern with a rotating magnetic field that rotates within the pattern plane. An ion implantation transfer path is known in which magnetic bubbles are transferred by a charged wall that is magnetized by a rotating magnetic field and generated at the boundary of an ion implantation pattern (US Pat. No. 3,618,054).

The permalloy transfer path has approximately 2 bubble diameters between magnetic bubble transfer patterns to prevent backward movement of magnetic bubble transfer.
Since a gap of /3 or less is required, there is a limit to increasing the density of elements due to restrictions on pattern formation by photolithography technology.

In the ion implantation circuit, the charged wall that occurs at the boundary between the ion implantation part and the non-ion implantation part is used to transfer the bubbles, so there is no need for a gap to prevent the bubbles from moving backwards, and the gap is extremely small, about 1 μm or less. You can transfer bubbles.

Therefore, we adopted two types of magnetic bubble transfer paths: an ion implantation transfer path suitable for high density in the minor loop section that stores and holds information, and a permalloy transfer path suitable for this in the information input/output section. It has been proposed as a method to realize high-density and high-speed information by using a combined magnetic bubble memory element (Japanese Patent Laid-Open No. 5
7-186287).

[Problem that the invention seeks to solve]

However, when a magnetic bubble memory element configured in this way performs a memory operation using an ion implantation transfer path, there is a range in which the bubble transfer operation of this ion implantation transfer path can be performed with good stability, the so-called bias magnetic field margin. The problem was that it was restricted.

SUMMARY OF THE INVENTION An object of the present invention is to provide a magnetic bubble memory device equipped with an ion implantation transfer path whose stable operating characteristics can be improved by improving a portion of the ion implantation transfer path.

[Means for solving the problem] According to an embodiment of the present invention, the pattern curvature of the portion of the transfer pattern constituting the ion implantation transfer path where bubbles are transferred from the cusp portion to the tip portion is changed from the tip portion to the tip portion. By configuring the ion implantation transfer path with a pattern shape that is larger than the pattern curvature of the portion that transfers bubbles to the cusp portion, a magnetic bubble memory element that can obtain a stable bias magnetic field margin is provided.

[Effect]

The magnitude of the driving force that pulls out the bubbles at the cusp portion of the ion implantation transfer pattern corresponds to the magnitude of the pattern curvature of the portion that transfers the bubbles from the cusp portion to the tip portion.By increasing this curvature, a large driving force can be obtained. can occur, and stable bubble transfer is achieved.

〔Example〕

The present invention will be described in detail below using one drawing.

FIG. 2 is an enlarged plan view illustrating a magnetic bubble memory device according to the present invention. In the figure, m is a minor loop that stores information, RML is a read major line that transfers read information, and WML is a write major line that transfers write information. Further, D is a bubble detector that converts magnetic bubbles into electrical signals, G is a bubble generator that generates magnetic bubbles, and R is a replicate game 1 that copies or transfers the information of the minor loop m to the read measure line RML. TS is a transfer gate that transfers information on the light major line WML to the minor loop m, or a swap gate that simultaneously sweeps information on the minor loop m to the major line WML at the same time as the transfer, and exchanges information between the two. Further, GR surrounding these outer peripheries is a guardrail for preventing magnetic bubbles from entering from the outer periphery, BP is a bonding pad for connecting these transfer circuits with an external circuit, and MP is a monitor pattern. Also, Replicate Gate R.

The swap gate TS and the bubble generator G are controlled by whether or not a current flows in a certain direction through a conductor in a separate layer arranged in a special relationship with the permalloy transfer pattern, and in the figure, the conductor portion is indicated by a thick solid line. The thin solid line indicates the permalloy transfer pattern.

Further, in the figure, the area within the minor loop m indicated by the broken line is formed by an ion implantation transfer path, and the area outside thereof is formed by a barmy transfer path.

FIGS. 3(a) and 3(b) show the permalloy transfer path described above.

The ion implantation transfer paths are shown, and the permalloy transfer path shown in Figure (a) is made of bubble magnetic material L.
A soft ferromagnetic thin film pattern PT such as permalloy is formed on the PH via a spacer film SP such as SiO2. A moving magnetic pole is formed by magnetizing this pattern PT with a rotating magnetic field Hn that rotates within the plane of this pattern. Magnetic bubble B is attracted to this moving magnetic pole and transferred in the direction of arrow P along pattern PT. In contrast, the same figure (b
) The ion implantation transfer path ■ shown in ) is made of bubble magnetic material L.
Ion implantation of H2", Ha", Ne, etc. is partially applied to the surface of the PH. (2) ON is the ion implantation layer implanted in this manner. The area around the ion implantation transfer pattern IPT is the region where the ion implantation + is implanted. By magnetizing this ion implantation layer ION with a rotating magnetic field (IR) that rotates within the pattern plane, a magnetic pole called a charged wall is generated that moves along the pattern IPT. The magnetic bubble B is attracted to this charged wall and transferred in the direction of arrow P along the pattern IPT. That is, in detail, as shown in FIG. 4, the transfer portion P! from the tip portion T to the cusp portion C of the pattern IPT!
is transferred in the direction of arrow P along the rotating magnetic field) (H
Corresponding to the rotation of , the next pattern IPT is sequentially transferred along the transfer section PO from the cusp section C to the tip section T.

As shown in the figure, the ion implantation transfer path does not have a gap g between patterns compared to the permalloy transfer path, and the ion implantation layer ION is formed inside the bubble magnetic material LPE, resulting in magnetic bubbles. Its feature is that it is closely spaced from B, and this provides excellent characteristics for high density.

FIG. 5 shows an example in which a minor loop m is constructed using an ion implantation transfer path having such characteristics and suitable for high density. This figure is an enlarged plan view of a main part showing a part of the minor loop m group, and the same parts as in FIG. 3 are given the same reference numerals. In the figure, the transfer patterns IPT are arranged in the inner direction of the minor loop with a period of λ to form ion implantation transfer paths I (It, Ix, Iδ), respectively.
Such an ion implantation transfer path I 1v I xHI
a is arranged in the inter-loop direction with a period of 2λ0,
Since two round trip bubble transfer paths are formed for one minor loop transfer path, two magnetic bubbles B can be packed into the area represented by the product of period λ and 2λD. Therefore, the memory bit size (cell size) in this case is λ, XλD, and the smaller the area, the higher the density. Furthermore, the sizes of these periods λ1 and λD are usually λI≠λ due to restrictions on transfer characteristics due to mutual interference between magnetic bubbles with respect to the diameter d of the magnetic bubble B used.
Selected in the range of D ridge 3-4d.

However, such ion implantation transfer paths If, Iz
, Is with period λ1. When increasing the density by reducing λD, the following problems occur.

FIG. 6 shows the transfer section Pt of the pattern IPT described above.

Bias magnetic field HB that can stably transfer bubbles to PO
The graph shows the results of determining the range of . The wider the range, the more stable the transfer operation is, and in practice, a margin of about 10% or more is usually sufficient. However, as is clear from the figure, the transfer section P! Although the bias margin of the transfer section Po is practically sufficient, it has become clear that the bias margin of the transfer section Po is insufficient in practice. That is, in order to stably transfer the bubbles through the ion implantation transfer path, there was a problem in the transfer section PO where the bubbles were pulled out from the cusp portion C, and a sufficient bias margin could not be obtained in practice.

Therefore, in the present invention, the ion implantation transfer path m1. m2. m3 is the ion implantation transfer pattern IPT as shown in FIG. It is formed by increasing the pattern curvature (reciprocal of the radius of curvature RO) of the transfer portion Pa from the cusp portion C to the tip portion T (the radius of curvature is R<>Ro). The pattern curvature of the transfer portion Po is large enough to provide sufficient driving force to pull out the bubble from the cusp portion C, and the pattern curvature of the transfer portion P+ is large enough to transfer the bubble from the tip portion T to the cusp portion C. Since the required driving force is small, there is no need to increase it so much. Although the pattern curvature structure of these transfer portions P2 and Po is provided in the left transfer path of the pattern IPT, the right transfer path is also formed to have the same pattern shape as described above.

In addition, in the above-mentioned embodiment, the case where the pattern shape of the ion implantation transfer path IPT was circular was explained, but the idea of the present invention is not limited to this pattern shape, and other basic patterns, Of course, the same effect as described above can be obtained even if the shape is applied to, for example, a snake shape, a diamond shape, or a triangle shape.

〔Effect of the invention〕

As explained above, according to the present invention, the pattern curvature of the transfer section that transfers bubbles from the cusp section to the tip section of the ion implantation transfer path, which is formed by alternately and continuously repeating the tip section and the cusp section.

Since the pattern curvature is made larger than the pattern curvature of the transfer section that transfers bubbles from the tip section to the cusp section, the driving force for bubble transfer from the cusp section to the tip section can be increased.
It has an extremely excellent effect of providing stable bubble transfer characteristics.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of an ion implantation transfer path for explaining one embodiment of the magnetic bubble memory element according to the present invention, and FIG.
The figure is a plan view showing a magnetic bubble memory element according to the present invention.
FIGS. 3(a) and 3(b) are enlarged perspective views of essential parts explaining the permalloy transfer path and the ion implantation transfer path, and FIG. 4 is a schematic diagram illustrating the state in which bubbles are transferred to the ion implantation transfer pattern. FIG. 5 is an enlarged plan view of a main part showing a minor loop group constituted by ion implantation transfer paths, and FIG. 6 is a characteristic diagram showing bias magnetic field margins at the tip and cusp portions of the ion implantation transfer pattern. m""Minor loop, I, Ii, It, Ia...Ion implantation transfer path, IPT...Ion implantation transfer pattern, T...Tep portion, C...Cusp portion, Py
, po... Transfer unit. 1st toe ('i-7 quick transfer connection IPT...Ion implantation H transfer try-"il...
Step bitterness C=・Cusp” part T't, Fo...Transfer AI 2nd eye 4th eye ■) IR early S mouth FIF.

Claims (1)

[Claims] 1. A transfer section that includes an ion implantation transfer path configured by connecting a plurality of ion implantation transfer patterns formed by alternately and continuously repeating a tap section and a cusp section, and transfers bubbles from the cusp section to the tip section. A magnetic bubble memory element characterized in that a pattern curvature is made larger than a pattern curvature of a transfer section that transfers bubbles from a tip section to a cusp section.