JPS60251589A - Formation of magnetic bubble memory element - Google Patents

Abstract

PURPOSE:To form the magnetic bubble memory element where fine pattern gaps can be formed by providing projections and recesses to the base of a ''Permalloy(R)'' layer. CONSTITUTION:The base layer 11 of the ''Permalloy(R)'' layer is vapor-deposited on a crystal 10 for bubbles in a projection and recess shape, and then cut layers are formed at boundary parts owing to the projections and recesses. Then, the ''Permalloy(R)'' layer is coated with photoresist to form a resist pattern and unnecessary parts are etched to obtain a ''Permalloy(R)'' pattern with gaps. Thus, the magnetic bubble memory element where the fine pattern gaps can be formed is manufactured.

Description

DETAILED DESCRIPTION OF THE INVENTION TECHNICAL FIELD OF THE INVENTION The present invention relates to a method for making a magnetic bubble memory element used in a storage device such as an electronic computing device.

Background of the Technology As semiconductor technology advances, magnetic bubble memory devices are constantly required to have higher storage densities.

For this reason, permalloy patterns, which are storage elements of memory devices, are becoming increasingly finer.

Prior Art and Problems Conventionally, gaps in permalloy patterns have been created by photolithography. Therefore, the gap size is determined by the resolution limit of photolithography, and the limit is about 0.5 μm, and there is a problem in that it is difficult to form a gear knob smaller than this.

OBJECTS OF THE INVENTION In view of the above-mentioned conventional problems, an object of the present invention is to provide a method for manufacturing a magnetic bubble memory element that can form a fine pattern gap.

According to the present invention, a magnetic bubble memory element has a fine soft magnetic material pattern and magnetizes the soft magnetic material pattern by a rotating in-plane magnetic field to drive a bubble. To provide a method for producing a magnetic bubble memory element, characterized in that unevenness is provided on a soft magnetic material layer base at a location corresponding to a gap in between, and a soft magnetic material pattern spanning the boundaries of the uneven portion is cut. This is achieved by

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

FIG. 1 is a diagram for explaining the present invention in detail, where 1 is a bubble crystal, 2 is a first base layer, 3°3' is a second base layer, and 4 and 4' are permalloy layers. are shown respectively.

In the figure, a first base layer 2 is partially shaved to form a concave portion a and a convex portion a. Although the second underlayer 4 is provided between the first underlayer 2 and the permalloy layer 4 in the figure, it is not necessarily necessary in reality. Generally, when the boundary between the uneven parts of the first base layer 2 has a steep taper angle (θ in the figure), the film laminated thereon by vapor deposition or the like cannot maintain its cross-sectional shape, as shown in the figure. It is then cut into two parts 3, 3'. The same applies to the case where it is laminated on top of this. This phenomenon is related to the thickness T2 and taper angle θ of the first underlayer 2 and the thickness T4 of the permalloy layers 4 and 4'. According to our experience, when a permalloy film with a thickness of 3,000 layers is formed by vapor deposition, if θ has a steepness of 60° or more, the thickness T2 of the first base layer 2 may be about 2,000 to 3,000 layers. . or,
The width of this custom-made cutting groove is so narrow that it cannot be measured. However, the existence of this groove can be confirmed by transmitting light from below the wafer.

FIG. 2 is a diagram for explaining the method for producing a magnetic bubble memory element according to the present invention, in which a is a top view of the element and b is a sectional view taken along line bb in diagram a.

In the figure, 10 indicates a bubble crystal, 11 a permalloy base layer, 12 a permalloy pattern, and 13 a gap.

In this embodiment, as shown in FIG. 2, 5i02 and the like are formed in an island shape as the base layer 11 of the permalloy layer every other bit. Next, a permalloy layer is deposited thereon.

At this time, cutting grooves are formed in the permalloy layer at the boundary due to the unevenness caused by the base 11. Next, a photoresist is applied onto this permalloy layer, and a resist pattern is created by a photolithography process. In this case, since gaps are already formed in the permalloy layer, the resist pattern may be continuous without gaps. Next, unnecessary portions of the permalloy layer are removed by etching to create a permalloy pattern 12.

In this embodiment method of creating a magnetic bubble memory element in this way, gaps are already formed when creating a resist pattern, and the pattern can be continuous like the permalloy pattern 12 in FIG. Photolithography is easy, and formation of fine gaps is also easy.

Furthermore, since the magnetic bubble memory element produced by the method of this embodiment has a very narrow gap, the memory operation is good.

In the method of the present invention, when a physical etching method such as ion etching is used for etching permalloy,
Permalloy residue may occur at the sharply uneven boundaries of the base. For this reason, it is desirable that the taper angle θ outside the gear part be made gentle. Such a method of forming a part of the taper angle steeply and the other part gently has already been proposed in ``Japanese Patent Application No. 114164/1981 (filed on June 27, 1988).

FIG. 3 is a diagram showing an example in which the method of the present invention is applied to a dual spacer system, in which a is a plan view and b is an enlarged sectional view taken along line bb in diagram a. In the figure, 20 is a bubble crystal, 21 is a first spacer layer using 5i02,
22 is a second spacer layer using POLS resin, 23 is a third spacer layer using 5i02, 24 is a permalloy pattern with a large period, and 25 is a permalloy pattern with a small period.

This application example uses a permalloy pattern 25 with a small period in the information storage part and a permalloy pattern 24 with a large period in the other parts, and in order to make the bubble driving force the same in both patterns, the thickness of the spacer is changed to make a so-called dual pattern. In this case, the first and second spacers 2
A gap 26 is formed by a steep difference between the points 1 and 22.

Effects of the Invention As explained in detail above, the method for producing a magnetic bubble memory element according to the present invention makes it possible to easily form minute gaps in a permalloy pattern by providing unevenness on the base of a permalloy layer. This has a great effect in that it contributes to increasing the storage density of bubble memory elements.

[Brief explanation of drawings]

Fig. 1 is a diagram for explaining the principle of the method for producing a magnetic bubble memory element of the present invention, Fig. 2 is a diagram for explaining the method for producing a magnetic bubble memory element according to the present invention, and Fig. 3 is an application of the present invention. It is a figure which shows an example. In the drawing, 10 is a crystal for bubbles, 11 is a base layer, 1
2 indicates a permalloy pattern, and 13 indicates a gap. Patent applicant Fujitsu Limited Patent application agent Akira Aoki Patent attorney Kazuyuki Nishidate Patent attorney Yukio Uchida Patent attorney Akira Yamaguchi Figure 1 Figure 2 Figure 3

Claims (1)

[Claims] 1. In a magnetic bubble memory element that has a fine soft magnetic material pattern and uses a rotating in-plane magnetic field to magnetize the soft magnetic material pattern and drive a bubble, a gap between the soft magnetic material patterns is provided. 1. A method for producing a magnetic bubble memory element, which comprises providing irregularities on a soft magnetic material layer base at corresponding locations, and cutting a soft magnetic material pattern that straddles boundaries of the irregularities. 2. The method of manufacturing a magnetic bubble memory element according to claim 1, characterized in that the taper angle of the unevenness is made steep to 60° or more. 3. Adjust the taper angle of the above unevenness only to the soft magnetic gap 6
2. The method of manufacturing a magnetic bubble memory element according to claim 1, wherein the magnetic bubble memory element is made larger than 0°, and other portions are made looser than the gap portion.