JPS6036088B2 - Method for manufacturing magnetic bubble memory element - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnetic bubble memory device, and more particularly, to a magnetic bubble memory device that uses a cured film of a heat-resistant polymer resin as an insulating film to reduce the step difference and expand the operating margin. Regarding the manufacturing method.

Generally, a magnetic bubble memory element has a cross-sectional structure as shown in FIG.

That is, a first insulating film 2 and a conductive pattern 3 used for generating and extinguishing magnetic bubbles are formed on a magnetic film 1 that holds magnetic bubbles and is deposited on a non-magnetic substrate (not shown). ,
A second insulating film 4 and a soft magnetic material pattern 5 for transferring and detecting magnetic bubbles are successively deposited in a thin layer.

In a magnetic bubble memory element having such a structure, a step as shown in FIG. 1 occurs at a place where a part of the soft magnetic material pattern 5 overlaps with the luteal guide pattern 3, and the magnetic bubble is The disadvantage was that the operability decreased.

In order to eliminate these drawbacks and increase the transfer margin, as shown in Figure 2, for example, PIQ (Hitachi Chemical Co., Ltd. trade name, Polyimideisoin) is used.
The use of the second insulating film 6 made of a cured film of a heat-resistant polymer resin such as Droqumazolindion is extremely effective in reducing the level difference.

However, although using PIQ or the like for the second insulating film is extremely effective in reducing the level difference, there are problems as described below in manufacturing the element having the structure shown in FIG. 2 with high precision. That is, since the European magnetic material pattern 5 must have an extremely fine and accurate shape, the soft magnetic material film is processed by physical dry etching such as ion milling using a resist pattern as a mask, and then oxygen plasma By chemical dry etching using
The remaining resist pattern is removed to form a soft magnetic material pattern.

When the remaining resist pattern is removed by chemical dry etching using oxygen plasma, the second insulating film 6 made of a cured film of polymer resin such as PIQ will also be etched at the same time, and if the etching is severe, There is even a possibility that the European magnetic material pattern 5 may peel off.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for manufacturing a magnetic bubble memory element that solves the above-mentioned conventional problems and can reliably form a magnetic bubble memory element with small steps and a large operating margin.

In order to achieve the above object, the present invention uses a heat-resistant polymer resin film as a second insulating film to reduce the level difference, and on this second insulating film, a material selected from alumina, silicon dioxide, etc. A third insulating film made of an inorganic insulating film is deposited to prevent the second insulating film from being etched.

The present invention will be explained in detail below. FIG. 3 is a process diagram showing an embodiment of the present invention.

First, as shown in FIG. 3a, a silicon dioxide film with a thickness of 20 mm is deposited as a second insulating film 2 on a magnetic net film 1 capable of holding magnetic bubbles by high-frequency sputtering. Then, the Mo and Au films are deposited by a normal vapor deposition method such as an electron beam heating method or a resistance heating method, and a photoresist pattern is processed by ion milling using a mask to form a conductor pattern 3.

Next, a solution prepared by dissolving PIQ in a 1:1 mixture of N-methyl-2-pyrrolidone and N.N-dimethylacedeamide is spin-coated and cured by heat treatment at, for example, 350 oo for 1 hour.
As shown in FIG. 3b, a second insulating film 6 is formed.

Furthermore, a third insulating film 7 made of an alumina film is deposited over the entire surface using a normal vapor deposition method or a high frequency sputtering method. In the present invention, the thickness of the second insulating film is important.

If the film thickness is too thin, the effect of reducing the level difference will be insufficient, and in extreme cases, the electrical insulation between the conductive pattern 3 and the soft magnetic pattern 5 will become poor. On the other hand, if it becomes too thick, the distance between the garnet film 1 and the soft magnetic material pattern 5 becomes too large, which causes various troubles such as bubble detection. On the other hand, in a magnetic bubble memory element, the margin of the bias magnetic field needs to be 10% or more in practice, but if the thickness of the second insulating film 6 is 10% or less, the effect of reducing the step difference is not effective. The above margin does not fall below 10% due to insufficient capacity.

Moreover, in this case, the electrical insulation between the conductor pattern 3 and the magnetically sensitive pattern 5 will also be poor, so in the present invention, the thickness of the second insulating film 6 is 10 mm or more. There is a need. However, since the detector for detecting magnetic bubbles is placed on the third insulating film 7, if the second insulating film 6 is too thick, the output of the detector will drop significantly. Resulting in.

Therefore, the distance between the net film and the detector must be below a certain value, and the film thicknesses of the first, second and third insulating films 2, 6 and 7 should be Approximately 140
It is preferable that it be less than the enemy.

The first insulating film 2 needs to have a certain degree of thickness in order to relieve the stress of the garnet film 1, but if it is too thick, the current required for bubble generation will increase significantly. .

For this reason, the film thickness of the first insulating film 2 is approximately 100~
The thickness range is approximately the same whether the film is made of Si02 or a heat-resistant resin. The third insulating film 7 serves as a mask for physical dry etching such as ion milling used for etching soft magnetic films and oxygen plasma etching (chemical dry etching) used for removing the remaining photoresist pattern. act.

Therefore, for example, a film made of an inorganic insulating material having high resistance to the above etching, such as aluminum oxide, chromium oxide, titanium oxide, silicon dioxide, silicon monoxide, and silicon nitride, is used as the third insulating film. The thickness of the third insulating film needs to be about 2 times thicker or more as a mask for self-etching, and if it is thinner than this, its effect as a mask will be insufficient.

As described above, the sum of the thicknesses of the first, second, and third insulating films is 140 mm or less, and the thickness of the second insulating film is approximately 100 to 40 mm.

Therefore, the second insulating film (more than 10 layers) and the third
The thickness of the insulating film (2 mm or more) is appropriately selected based on these values. After forming the third insulating film 7 by the above method, as shown in FIG. A photoresist pattern 9 is formed.

Using the photoresist pattern 9 as a mask, the exposed portion of the permalloy film 8 is removed by ion milling using Ar ions, and the remaining photoresist pattern 9 is removed by plasma etching using oxygen plasma, as shown in FIG. As shown in d, a European magnetic material pattern 10 made of a permalloy film is formed.

In the etching process described above, it is inevitable that the alumina film 7 is etched and its thickness is slightly reduced, but since the alumina film 7 has high resistance to etching, the surface of the second insulating film 6 will not be exposed and etched.

As is clear from the above description, according to the present invention, since a cured film of a heat-resistant polymer resin such as PIQ is used as the second insulating film, the level difference caused by the thickness of the conductor pattern can be significantly reduced. , the operating margin can be significantly increased.

Moreover, since the third insulating film is deposited on the second insulating film and the soft magnetic film is etched and the remaining photoresist pattern is removed, the second insulating film is etched during the etching process. Therefore, an extremely reliable magnetic bubble memory element can be formed.

In addition, in the present invention, the heat-resistant polymer resin is 200
It refers to a resin that is stable for a long time in CO, and further preferably has a viscosity of 200 PS or less and no deformation such as cracking during curing.

Those that satisfy these conditions and can be used in the present invention include PIQ polyimide resin, epoxy resin, phenol resin, polycarbonate resin,
Examples include polyamide/imide resins and polybenzimidazole resins, and two or more of these may be used in combination.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the structure of the main part of a subordinate magnetic bubble memory element, FIG. 2 is a diagram showing that the step is reduced in the present invention, and FIG. 3 is a diagram showing an embodiment of the present invention. It is a process diagram. 1: Magnetic one-net film, 2: First insulating film, 3: Conductor pattern, 4, 6: Second insulating film, 5: Soft magnetic material pattern, 7: Third insulating film. Sai/Zouzai 2zuzaijizai

Claims (1)

[Claims] 1. A method for manufacturing a magnetic bubble memory element including the following steps. (a) A step in which a magnetic film capable of holding magnetic bubbles is deposited by laminating a first insulating film, a conductive pattern, and a second insulating film made of a cured film of a heat-resistant polymer resin.(b)
Step (c) of depositing a third insulating film on the entire surface of the second insulating film; Step (d) of depositing a soft magnetic film on the third insulating film; and (d) Desired coating on the soft magnetic film. Step (e) of forming a partial photoresist pattern; Step (f) of removing the exposed portion of the soft magnetic film by physical dry etching; Step 2 of removing the resist pattern by chemical dry etching; 2. The method of manufacturing a magnetic bubble memory element according to claim 1, wherein the third insulating film is selected from the group consisting of an aluminum oxide film, a chromium oxide film, a titanium oxide film, and a silicon nitride film. 3. The method of manufacturing a magnetic bubble memory device according to claim 1 or 2, wherein the physical etching is ion milling, and the chemical dry etching is plasma etching using oxygen plasma. 4 The total thickness of the first, second, and third insulating films is approximately 1400 nm or less, the thickness of the first insulating film is approximately 100 to 400 nm, and the total thickness of the third insulating film is approximately 1400 nm or less, and Claim 1: The film thickness is approximately 20 nm or more.
A method for manufacturing a magnetic bubble memory element according to item 1, 2 or 3.