JPS622386B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field of the Invention The present invention relates to a magnetic bubble memory device that is a combination of an ion implantation bubble device and a permalloy bubble device.

Background of the Technology Recently, in magnetic bubble memories, a method has been used to improve the storage density by forming bubble transfer paths by ion implantation. However, the bubble transfer path using this ion implantation method has the disadvantage that the driving force of its driving pattern is smaller than that of the conventional permalloy pattern, and is particularly useful for function gates that require a relatively strong driving force and, in turn, a strong bubble trapping force. The design was difficult. Therefore, it is considered that a permalloy pattern can be used in such a location, and a magnetic bubble memory device that is a combination of an ion implantation bubble device and a permalloy bubble device has been developed.

Prior Art and Problems FIG. 1 is a diagram for explaining a function gate portion of a magnetic bubble memory device which is a combination of a conventional ion implantation bubble device and a permalloy bubble device. In the figure, the hatched area 1 is the ion implanted region, 2 is the non-ion implanted region, 3 is the boundary thereof, 4 is the minor loop formed in the ion implanted region, and 5 is the permalloy pattern in the non-ion implanted region. The formed major line, 6 indicates a permalloy pictorial pattern constituting a gate portion, and 7 indicates a gate conductor.

Conventionally, ion implantation has been performed so that a minor transfer path consisting of a non-ion implanted region is formed within a certain area on the surface of such a bubble crystal, and outside the certain area on the bubble crystal where the ion implantation has not been performed. A major transfer path is formed by a permalloy pattern in the magnetic bubble memory element in which magnetic bubbles are transferred between the major transfer path and the minor transfer path. There is a boundary 3 that separates the non-ion-implanted region 1 from the non-ion implanted region 2, and the bubble operated in the gate section always passes through this boundary once. However, due to the unique potential shown in Figure 2, this boundary has the disadvantage that the bubble is easily trapped at the boundary (due to attraction) or is difficult to cross over (due to repulsion), which prevents the original gate operation. It was hot.

Purpose of the Invention In view of the above-mentioned conventional drawbacks, the present invention provides a magnetic bubble memory device in which an ion-implanted bubble device and a permalloy bubble device are combined, so that bubbles can easily pass through the boundary between an ion-implanted region and a non-ion-implanted region. The object is to provide a magnetic bubble memory element.

Structure of the Invention According to the present invention, ion implantation is performed so that a minor transfer path consisting of a non-ion implanted region is formed at least within a certain region of the surface of the bubble crystal, and A major transfer path is formed by a permalloy pattern outside a certain area where ions are not implanted, and in a magnetic bubble memory element in which magnetic bubbles are transferred between the major transfer path and the minor transfer path, A bubble passage path is provided at the boundary between the ion implantation region and the non-ion implantation region outside the predetermined region so that the ion implantation profile changes gently only in a narrow range sufficient for the bubble to pass through. This is achieved by providing a magnetic bubble memory device characterized by:

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

FIG. 3 is a diagram for explaining the magnetic bubble memory element according to the present invention, in which a shows a metal mask for projection exposure, a′ shows the state of the photoresist after being exposed and developed using the mask, and b shows a metal mask for projection exposure. The state of the metal vapor deposited film (ion implantation mask) after etching is shown, and c shows the bubble passage formed so that the ion implantation profile changes smoothly.
In the figure, 10 is a bubble crystal, 11 is a metal vapor deposited film, 12 is a photoresist, and 13 is a metal mask.

The metal mask 13 has a triangular protrusion 1 as shown in figure a.
3a, and its design dimensions are such that the base W of the triangle is greater than or equal to the bubble diameter, and the height H is such that the portion of the pattern width that is less than the resolution of the exposure apparatus is at least greater than the bubble diameter.

When this metal mask 13 is used to expose the photoresist 12 deposited on the metal film 11 deposited on the bubble crystal 10, as shown in figure a', the light goes around the part below the light resolution of the protruding part of the triangle 13a, so the so-called The image is blurred and exposed. As a result, the photoresist 12 has an extremely tapered triangular portion 12.
a is formed.

When the metal vapor deposited film 11 is ion-etched in this state, a tapered triangular pattern 11a similar to the triangular part of the photoresist is formed as shown in Figure b.
is formed. When ion implantation 15 is performed using this metal pattern as a mask 14, the amount of ions to be blocked differs depending on the thickness of the mask 14 as shown in Figure c. 14, and as a result, the projected range of the ion in the crystal under the tapered portion changes with a certain slope.) The projected range L of the ion has a distribution. As a result, the strained region of the ion-implanted layer 16 changes gently at the boundary (section a). When the distribution of strain in the ion-implanted layer is stepwise, the potential distribution is as shown in Fig. 2 described above, but when it changes gradually, the distribution of potential 17 also changes gradually, as shown in Fig. 4. do. Therefore, the potential wall 18 that the bubble must overcome when passing through the boundary is lower when the bubble changes gradually than when it changes stepwise, and therefore the margin for the bubble to cross the boundary is wider. .

As a method of intentionally "blurring" a part of the boundary between the ion-implanted region and the non-ion-implanted region, a pattern having the following shape can be used. FIG. 5 shows a boundary 21 between an ion-implanted region 19 and a non-ion-implanted region 20 instead of providing a triangular protrusion.
In this case, a triangular recess 22 is provided, and in FIG. 6, a large number of fine patterns 23 below the resolution are provided close to each other, so that the entire image becomes a halftone. The effects of the embodiment shown in FIGS. 5 and 6 are similar to those of the embodiment shown in FIG.

Effects of the Invention As described above in detail, the magnetic bubble memory element of the present invention reduces distortion in that portion by “blurring” only the portion where the bubble passes through the boundary separating the ion-implanted region and the non-ion-implanted region. The profile can be changed smoothly, and as a result, the potential wall is lowered, making it easier for bubbles to pass, which is a great effect.

[Brief explanation of the drawing]

Figure 1 is a diagram for explaining the function gate part of a magnetic bubble memory device that combines an ion-implanted bubble device and a permalloy device, and Figure 2 shows the potential at the boundary between the ion-implanted region and the non-ion-implanted region. FIG. 3 is a diagram for explaining the magnetic bubble memory element according to the present invention, FIG. 4 is a diagram showing the potential at the boundary between the ion-implanted region and the non-ion-implanted region, and FIGS. 5 and 6. FIG. 3 is a diagram for explaining another embodiment. In the drawings, 10 is a bubble crystal, 11 is a metal vapor deposited film, 12 is a photoresist, and 13 is a metal mask.

Claims (1)

[Scope of Claims] 1. Ion implantation is performed so that a minor transfer path consisting of a non-ion implanted region is formed at least in a certain region on the surface of the bubble crystal, and the ion implantation is performed on the bubble crystal. In a magnetic bubble memory element in which a major transfer path is formed by a permalloy pattern outside the fixed area, and magnetic bubbles are transferred between the major transfer path and the minor transfer path, the ion implantation area within the certain area and the A bubble passage path is provided at the boundary with a non-ion implantation region outside the region, the bubble passage being formed so that the ion implantation profile changes gently only in a narrow range sufficient for the bubble to pass through. magnetic bubble memory element.