JPS6342352B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to ion implantation bubble memory devices, particularly
The present invention relates to a method for manufacturing a high-density ion-implanted bubble memory device with a period of 4 μm or less.

[Conventional technology]

Figure 7 shows a continuous disk magnetic bubble element constructed with a conventional ion implantation pattern, where A is a plan view, B is a cross-sectional view taken along line B-B in figure A, and C is a cross-sectional view taken along line C-C in figure A. It is. 1p... is a disk-shaped pattern, which is continuous without being independent. These disk patterns 1
p... is made of a deposited film such as gold (Au), etc., and when ions are implanted into the surface of the bubble crystal 2 to about 30% of the film thickness using this disk pattern 1p... as a mask, the disk pattern 1p... By ion implantation, the direction of magnetization is tilted in the plane only in the region 3 other than below. The magnetization direction of the disk pattern portion where ions are not implanted remains perpendicular to the surface.

In a magnetic bubble element having such an ion implantation pattern, when a rotating magnetic field in an in-plane direction is applied from the outside, the bubble B moves along the outer periphery of the disk pattern due to movement of the charged wall.

Such a continuous disk type magnetic bubble element is characterized in that a disk pattern can be easily produced. Adjacent patterns in ion implantation devices are not separated, and the pattern itself is relatively simpler than that of permalloy devices, so it is possible to achieve higher densities than permalloy devices using the same exposure technology. It is expected that they will have sex. However, as the bubble diameter becomes smaller and the period of each disk becomes finer, especially less than 2 μm, it is difficult to form a sharp gap G at the corner between adjacent disk patterns, resulting in a rounded shape. .

Normally, to form such a fine pattern,
The method shown in Figure 8 is adopted. A and B in FIG. 8 are cross-sectional views showing a conventional fine pattern forming method. First, as shown in A, a pattern material layer 1 is formed on the bubble crystal 2 by vapor deposition or the like,
A resist pattern 4p of thickness t ₂ made of a photoresist material is formed thereon by photolithography. The symbol _g1 indicates the gap width (lower base width) of the resist pattern 4p. After that, the pattern material layer 1 is etched and the resist pattern 4p is removed, and a mask pattern 1p for ion implantation is formed on the bubble crystal 2, as shown in FIG.
The symbol _g2 indicates the gap width (lower base width) of the pattern 1p.

When forming this pattern 1p using chemical etching technology, the gap width g ₂ is limited to 1 μm. If the pattern exposure time of the photoresist material is made shorter than the standard time, the gap width g ₁ of the mask pattern can be made smaller than 1 μm, but the gap g ₂ is at most 0.5 μm. Therefore, it is difficult to form a pattern in which the dimensions of the gap G gradually change as shown in FIG. 7 and the gap is extremely small at the innermost portion using the conventional method as described above.

Therefore, in order to actually realize a device with a period of 2 μm, reproducibility at fine points in the pattern becomes an issue, and if mass production is considered, it is expected that problems will occur with the conventional light exposure technology, such as yield. Ru.

The technical problem of the present invention is to solve such problems in the conventional contiguous disk type bubble memory device, and to solve the problem in the conventional continuous disk type bubble memory device. The object of this invention is to make it possible to create a high-density ion-implanted bubble memory element with stable pattern quality by applying the fine gap creation method disclosed in Publication No. 137023 (filed on December 26, 1981).

[Means for solving problems]

The technical means of the present invention taken to solve this problem is to create an ion implantation pattern on the surface of a bubble crystal and propagate a bubble magnetic domain using the pattern. At least one layer of mask film is formed thereon, a first resist pattern having a substantially circular shape which is independent of each other at a period of 1 bit length is formed thereon, and then a pattern width enlarging layer is further formed thereon, and then a pattern width enlarging layer is formed thereon. A method is adopted in which the resist layer and the pattern width enlarging layer are etched by an etching method using ions to complete a resist pattern, and ions are implanted using a mask pattern created using the resist pattern as a mask.

That is, the present invention uses a circular shape, which is the simplest to photolithography and is easy to obtain reproducibility, as a basic bubble propagation path, and uses a method of thickening the pattern established by the fine gap forming technology to create a circular shape that is similar to the adjacent one. It connects independent patterns to finally complete a continuous disk pattern.

[Effect]

According to this technical means, the contagious
formed on the layer to constitute the disk,
A pattern width enlarging layer is laminated on the circular independent resist patterns. At this time, the distance between adjacent patterns is narrowed by the pattern width enlarging layer, and the circular resist pattern becomes thicker.

Next, patterning is performed by ion etching or the like, but at this time, the periphery of each circular resist pattern becomes thicker due to redeposition from the pattern width enlarging layer material generated during etching.

As the outer periphery becomes thicker in this way, a resist pattern in the form of a continuous disk, in which the outer peripheries slightly touch each other, is completed. By using this resist pattern as a mask and etching the layer of contiguous disk material, a contiguous disk with a sharp outline is completed.
By implanting ions using this contagious disk as a mask, contagious
Even a high-density ion-implanted magnetic bubble element with a small disk period can be manufactured with good reproducibility and high yield.

[Example] Next, how the method for manufacturing an ion-implanted bubble memory device according to the present invention is actually implemented will be explained using an example. Figure 1 shows gold (Au) as above.
This shows the shape of a continuous disk pattern 1p consisting of, etc. In order to finally form this pattern, the resist layer 4 on the Au layer 1 shown in FIG. 2 is patterned to form isolated circular patterns 4p as shown in FIG.
rays or ion beam exposure). If the pattern period is 2 .mu.m, the diameter of the circular resist pattern 4p is 1 to 1.25 .mu.m, and the gap _g1 is about 1 to 0.75 .mu.m.

The thickness of the mask layer 1 made of Au etc. is approximately 4000 mm.
Å, and the thickness of the resist layer 4 is 6000 Å. A pattern width enlarging layer 5 is laminated thereon as shown in FIG. Pattern width expansion layer 5 is made of Cu or NiFe
The film was formed by a vapor deposition method. Film thickness is 6000
It is about Å. At this time, the pattern shape is as shown in Figure 4B.
As shown in FIG. 2, the thickness of the pattern width enlarging layer 5 increases to a degree that the gap g ₂ <g ₁ .

This is further etched into the first and second layers by ion etching.
When the layer is etched, the upper side disappears from the position indicated by dashed line 6 in FIG. 4B. At this time, the area around the bottom of the resist pattern 4p is
In addition to being in the shadow of P and making etching difficult, the pattern width expanding layer 5 is reattached during etching, making the pattern thicker in the area indicated by 5P in FIG. 5B, resulting in continuous contiguous patterns.
Disc-shaped patterns 4p, 5p, . . . are completed.
In this case, since the circular pattern 4p is made thicker as it is, the shape at the point where the circles intersect becomes much sharper than when a continuous disk pattern is formed by exposure technology.

Using the thus completed contiguous disk-shaped patterns 4p and 5p as a mask, the Au layer 1 is etched by a technique such as ion etching, resulting in a contiguous disk pattern 1.
p... is formed into a sharp shape.

By using the thus produced sharp mask pattern 1p as a mask, ion implantation is performed by the method explained in FIG. 7, thereby producing a continuous disk type magnetic bubble element.

In the embodiment, a case where the circles overlap each other is shown, but if the gap between the two patterns is very narrow, they do not necessarily need to overlap as shown in FIG. 6A. Furthermore, as shown in FIG. 6B, each disk pattern 1p can be completely separated. In this case, the allowable limit for the interval between adjacent patterns 1p...
It is approximately 1/2 of the bubble diameter. Further, in the embodiment, a typical circular shape is used because it is the easiest to create, but other shapes such as an ellipse can also be used.

〔Effect of the invention〕

As described above, according to the present invention, a circular resist pattern, which is the simplest pattern, is used, and etching is performed with a pattern width expanding layer laminated thereon to thicken the circular resist pattern. It is possible to complete a resist pattern. Then, by patterning a continuous disk pattern using this sharp resist pattern as a mask, a sharp continuous disk pattern can be created. Therefore, dense contiguous
A disk-type ion-implanted bubble memory element can be manufactured with good reproducibility and high yield.

[Brief explanation of the drawing]

1 to 6 show examples of the present invention, in which FIG. 1 is a plan view of a continuous disk pattern, FIG. 2 is a cross-sectional view of a laminated state of resist layers, and FIG. 3 is a cross-sectional view of a resist pattern. A plan view and a cross-sectional view after fabrication, Fig. 4 is a plan view and a cross-sectional view after the pattern width enlarging layer is laminated, Fig. 5 is a plan view and a cross-sectional view after the pattern width enlarging layer is etched, and Fig. 6 is a contiguous view. - It is a top view which shows another Example of a disk pattern. FIG. 7 is a plan view and a sectional view showing a conventional continuous disk type ion-implanted magnetic bubble element, and FIG. 8 is a sectional view showing a conventional disk pattern forming method. In the figure, 1p is a continuous disk, 2 is a bubble crystal, 4p is a resist pattern,
5 indicates a pattern width expansion layer, and 5p indicates a thickened portion.

Claims (1)

[Claims] 1. When manufacturing a so-called ion-implanted bubble memory element in which an ion implantation pattern is created on the surface of a bubble crystal and a bubble magnetic domain is propagated by the pattern, at least one layer of mask film is formed on the bubble crystal, and 1. Approximately circular resist patterns that are independent of each other at a period of the bit length are created, and then a pattern width enlarging layer is further formed thereon, and then the resist pattern and the pattern width enlarging layer are etched by an etching method using ions to form a resist pattern. A method for manufacturing an ion implantation bubble memory element, comprising completing a pattern and performing ion implantation using a mask pattern created using the resist pattern as a mask.