JPS6134781A - Magnetic bubble memory element - Google Patents

Abstract

PURPOSE:To improve a ''Permalloy(R)'' pattern bubble transfer characteristic by heat-treating an insulation film between a conductor layer and a ''Permalloy(R)'' layer with a high polymer resin including a resist having thermal fuidity and decreasing level difference of a ''Permalloy(R)'' pattern. CONSTITUTION:On a substrate, a bubble magnetic film 1, the first insulation film 2 forming a spacer and a conductor layer 3 are layered. The second insulation film 4 between the layer and a ''Permalloy(R)'' pattern 5 is formed by a high polymer resin including a resist with thermal fluidity and heat-treated with an electromagnetic wave, etc. Then, the surface of the film 4 becomes flatter. Consequently, the level distance of the pattern 5 formed on a layer 4 is decreased and a ''Permalloy(R)'' pattern magnetic bubble transfer characteristic is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a magnetic bubble memory device suitable for high density and high integration.

[Background of the invention]

An example of the laminated structure of the main part of a conventional magnetic bubble memory element is shown in FIG. With the increasing density and integration of bubble elements,
Since the bubble diameter is also miniaturized, the saturation magnetic flux density 4πMs, which is a characteristic of the bubble material, and the bubble extinguishing magnetic field H0 increase. Therefore, an extra magnetic pole is generated at the stepped portion of the permalloy pattern 5 that intersects with the conductor pattern 3 due to the influence of the bias magnetic field. There was a drawback that the bubble transfer characteristics at the step portion of the permalloy pattern 5 deteriorated due to the influence of this magnetic pole. A second spacer 4 is used as a solution to this level difference.
By increasing the thickness of the film, the step difference that occurs in permalloy can be eliminated. However, permalloy pattern 5 and bubble magnetic film 1
Because the distance between them increases, the rotating magnetic field for driving the bubbles increases. This poses a major problem in the practical application of high-density bubble devices.

In order to solve the above problem, it is necessary to create a planar structure that keeps the distance between the permalloy pattern and the bubble magnetic film as small as possible, and reduces as much as possible the step difference that occurs on the permalloy pattern that intersects with the conductor pattern. One method for solving this problem is disclosed in Japanese Patent Laid-Open No. 55-22293. This method is
A heat-resistant polymer resin such as a polyimide resin is used as the second spacer film, and this method is currently the mainstream of magnetic bubble element planar processes. but,
At a practical level of the second spacer film thickness, a step, albeit gradual, is formed on the permalloy pattern that intersects with the conductor pattern. Up to a magnetic bubble with a diameter of 1 μm, the influence of this level difference is small and there is no problem. However, when the magnetic bubbles become even smaller, the influence of the above-mentioned step difference becomes noticeable and becomes a big problem when increasing the density of the magnetic bubble element.

[Object of the Invention] An object of the present invention is to provide a magnetic bubble memory element having a laminated structure that solves the above-mentioned conventional problems and particularly contributes to improving permalloy pattern transfer characteristics that intersect with a conductor pattern.

[Summary of the invention]

As a method of eliminating the step difference that occurs in the permalloy pattern at the portion that intersects with the conductor pattern, the step difference that occurs in the permalloy pattern can be eliminated by increasing the thickness of the second spacer layer between the conductor layer and the permalloy layer. However, if this film thickness is made too thick,
In particular, this is not a good idea as it may cause problems such as deterioration of the bubble transfer characteristics of the minor loop section that stores information or a decrease in the detection signal output of the bubble detector.

Therefore, by applying a heat-flowable polymer resin material onto the conductor pattern as the second spacer material, it is possible to avoid using the heat-resistant polymer resin disclosed in JP-A-55-22293. Similarly, the level difference that occurs on the permalloy pattern that intersects with the conductor pattern becomes gentle. Furthermore, the stepped portion becomes even gentler due to the heat flow phenomenon that occurs during subsequent heat treatment. However, in this state, the strength as a spacer film cannot be obtained. here.

AZ1350J (
Figure 2 shows the results of implanting P ions into a product manufactured by Shipley. As can be seen from this figure, the etching rate decreases as the ion implantation dose increases.

This means that the strength of the resist film increases. Therefore, by performing ion implantation into the spacer film described above, strength as a spacer film can be obtained. It goes without saying that similar effects can be obtained not only with P ions but also with other ions, and similar effects can be obtained with other thermofluid polymer resins such as 0FPR (product of Tokyo Ohka Kogyo Co., Ltd.). Effects can be obtained. Furthermore, as another method of obtaining strength as a spacer film, it is also possible to apply electromagnetic waves.

[Embodiments of the invention]

Hereinafter, one embodiment of the present invention will be explained with reference to the process diagram shown in FIG.

(8) First spacer (Stow) on the surface of the bubble magnetic film 1
) 2, conductor pattern (A u / M
o) Form 3. On top of this, an AZ1350J resist is spin-coated as the second spacer 4.

(b) Thereafter, heat treatment is performed at 150° C. for 30 minutes to further flatten the resist using the thermal fluidity of the AZ1350J resist. Then, in order to obtain strength as a spacer film, 10'2/c112 P ions are implanted.

(c) After forming the second spacer film described above, a permalloy pattern 5 is formed.

In this example, (YSmLuGd) a(
FeGa), 012 garnet film (film thickness 0.8 μm
, bubble diameter approximately 0.8 μI! 1) was used to fabricate a bubble element with a major line/minor loop configuration in which the minor loop bit period is 4 μm and the major line bit period is 16 μm. When 500e or more, an operating margin of 10% or more was obtained, and it was confirmed that the device obtained by the present invention has a good margin.

Furthermore, in this example, photoresist A is used as the second spacer layer.
Although the case where Z1350J is used has been described, the present invention can be applied to any other polymeric resin that has fluidity by applying heat after coating, not just a resist.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to reduce the level difference in the permalloy pattern that intersects with the conductor pattern, which is effective in improving the bubble transfer characteristics of the permalloy pattern at the intersection of the conductor pattern.

[Brief explanation of drawings]

Fig. 1 is a cross-sectional view of a conventional permalloy element, and Fig. 2 is a sectional view of a conventional permalloy element.
A diagram showing the relationship between the dose of ion implantation and the etching rate of AZ1350J resist, FIG. 3 is a process chart showing an embodiment of the present invention. '1... Bubble magnetic film, 2... First spacer, 3... Conductor,
4...Second spacer, 5...Permalloy pattern. 1st Figure □----2nd z Z Figure

Claims (1)

[Claims] 1. A magnetic film capable of holding magnetic bubbles laminated and deposited on a non-magnetic substrate, a first insulating film, a conductive pattern, a second
A magnetic bubble memory element comprising at least an insulating film and a soft magnetic material pattern, characterized in that the second insulating film is made of a polymer resin containing a resist having thermal fluidity. 2. The magnetic bubble memory device according to claim 1, wherein after the second insulating film is deposited, the second insulating film is thermally fluidized to become planarized. 3. After depositing the second insulating film, the second insulating film is planarized by heat fluidization, and then treated by ion implantation or by applying electromagnetic waves to the second insulating film. The magnetic bubble memory device according to scope 2.