JPS634487A - Magnetic bubble memory element - Google Patents

Abstract

PURPOSE:To remarkably reduce the stress of a protection film and to prevent the insulation breakdown between upper/lower lead writes by using a two-layer film obtained by laminating SiO2 film and a high polymeric resin film having specific film thickness respectively as a protection film. CONSTITUTION:The film obtained by laminating SiO2 film whose film thickness is 0.1-0.3mum and the high polymeric resin film 6'' whose film thickness is 1.5-10.0mum is used as the protection film. The SiO2 film is formed on a magnetic garnet 1 as a 1st layer insulation film 2, Au/Mo is vapor-deposited as a 1st layer conductor 3 to form a pattern by a photoetching process. Then a polyimide resin film is formed as a 2nd layer insulation film 4 to remove undesired polyimide film by photoetching. In order to form a 'Permally(R)' transfer line 5, the 'Permally(R)' film is coated by vacuum vapor-deposition, the pattern is formed by photoetching, then a SiO2 film 6' is coated to form the pattern by photoetching, the SiO2 film 6' is coated, surface treatment is applied to form a polyimide film 6''. After a connection hole is made by photoetching, a 2nd layer conductor 7 is formed, Al subjected to vacuum vapor deposition used for the 2nd layer conductor to form the pattern by photoetching.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a magnetic bubble memory device, and particularly to a magnetic bubble memory device that has good memory characteristics and is suitable for reducing defects in device fabrication.

[Conventional technology]

In the conventional magnetic bubble memory element, as shown in FIG. 2, the protective film is an 8jCh film 6 having a thickness of about 1 μm. This is mainly due to the excellent moisture resistance of the SiOx film.
This was chosen to ensure reliability against the external environment.

[Problem that the invention seeks to solve]

However, when this 5i02 film (thickness: 1 μm) is used as a protective film, there are the following problems. The first problem is that the characteristics of the permalloy transfer path 5 may deteriorate due to stress on the 5jOz film. This is thought to be because the magnetic properties of Shihermalloy change due to the stress of 5 iOz, but the details are unknown.

The second problem is that the first layer conductor 3 or permalloy 5
There is a problem of inevitable destruction between the conductor 7 and the second conductor 7. This occurs when the lead wire of the second conductor 7 and the lead wire of the first layer conductor 3 or permalloy 5 intersect, and occurs at each step of the process. In order to avoid this problem, it is necessary to adopt a planar arrangement so that the lead wires do not intersect, or to increase the thickness of the protective film. However, the former method increases the chip area, and the latter method increases stress.

[Means for solving problems]

In the present invention, in order to solve these problems, a film that is thick and has low stress is used as the protective film. Specifically, a 21-film is used in which SiO2 with a thickness of 0.1 to 0.3 μm and a polymer resin with a thickness of 1.5 to 10.0 μm are laminated thereon.

[Effect]

In this 211 film, the film thickness of 5jO2 is thin and its stress is significantly small. In addition, polymer resins have low stress, so even if the film thickness is increased, no problem arises. 1 more
According to the present invention, the thickness of the protective film can be set to 1.6 μm or more, making it possible to prevent dielectric breakdown between the upper and lower lead wires.

It is also possible to form the protective film using only a polymer resin, but in this case, the reaction between the polymer resin and the permalloy surface progresses, causing a problem in long-term reliability.

〔Example〕

An embodiment of the present invention will be described below with reference to FIG. On the magnetic garnet 1, a SiO2 film having a thickness of 1,000 yen is formed as a first I-insulating film 2 by sputtering. Then A u/M as the first layer conductor 3.

(Thickness: 3300/200) is deposited, and a pattern is formed by a photo-etching process. Next, a polyimide resin film (thickness: 3000 mm) is formed as the second layer insulating film 4, and unnecessary portions of the polyimide film are removed by photo-etching. Next, in order to form the permalloy transfer path 5, a permalloy film is deposited by vacuum evaporation, and a pattern is formed by photoetching. Next, a film with a thickness of 1500 was obtained by sputtering.
After applying the human 5jCh film 6' and further surface treatment, 1. A polyimide film with a thickness of 2 μm is formed. Next, after making a connection hole by photo-etching, the 21st conductor 7
form. Here, the second layer conductor is vacuum-deposited At(
A pattern was formed by photoetching using a film having a thickness of 1 μm.

〔Effect of the invention〕

According to the present invention, the thickness of 5i02 used as a part of the protective film can be set to 0.1 to 0.3 μm, and the stress can be significantly reduced. That is, the conventional film thickness 1
Compared to 5i (h) of μm, the stress can be reduced to less than i. Therefore, no deterioration in the characteristics of the permalloy transfer path was observed during the formation of the protective film.

Moreover, according to the present invention, S! The total film thickness of Os and polymer resin is 1.158 m or more. Therefore, the vertical distance between each lead wire of the 5g single-layer conductor or permalloy and the second layer conductor increases, and dielectric breakdown between the lead wires can be completely prevented.

Note that in the conventional 5i02 protective film (film thickness: 1 μm), when lead wires cross, there is a very high probability that dielectric breakdown will occur. For this reason, the upper and lower lead wires have an undesirable planar arrangement, and the chip area has also increased by about 10 inches.

That is, according to the present invention, the chip area can be reduced by about 10% compared to the conventional device.

Here, the basis of film thickness in the present invention can be explained.

The thickness of the 5tO2 film used as part of the protective film is required to be 0.1 μm or more to protect the permalloy surface, and preferably 0.3 μm or less to keep the stress below a predetermined value. The film thickness of the polymer resin laminated on 5j02 is required to be 1.5 μm or more in order to prevent dielectric breakdown, and it is practically desirable to be 10 μm or less in order to open connection holes.

Although the main effects of the present invention have been described above, the following effects are also expected according to the present invention. When mounting a memory chip, magnetic foreign matter often adheres to the chip surface. This foreign material may cause memory malfunction due to its magnetic interaction with the bubble. However, according to the present invention, the protective film on the chip surface can be made thicker. Therefore, the distance between the magnetic foreign matter attached to the chip surface and the bubble becomes large, and there is no negative effect.

In addition, in the present invention, the stress caused by the protective film has a negative effect on the permalloy transfer characteristics! # said to give. but,
This stress also affects the bubble garnet film.

In other words, the stress in the protective film is transmitted to the bubble garnet film through the first layer conductor and the first layer e-edge film, etc., and has a significant effect on the bubble garnet, especially at the ends of the first layer conductor pattern. . For this reason, bubble transfer is inhibited in the same portion, and the characteristics tend to deteriorate.

According to the present invention, the stress on the protective film is significantly reduced, so that it is also effective in solving this problem.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a magnetic bubble element showing an embodiment of the present invention;
FIG. 2 is a sectional view of a conventional magnetic bubble element. DESCRIPTION OF SYMBOLS 1... Magnetic garnet, 2... First layer insulating film, 3...
...Layer conductor, 4...Second layer insulating film, 5...Permalloy, 6.6'...3iαb6"...Polymer resin,
7...2nd l mouth 2nd

Claims (1)

[Claims] 1. In a magnetic bubble memory element having at least a first layer conductor and a second layer conductor via an insulating film on a magnetic film holding a magnetic bubble, and a protective film between the first layer conductor and the second layer conductor. , the thickness of the protective film is 0.1 to 0.3
A magnetic bubble memory element characterized by using a layered film of a .mu.m thick SiO_2 film and a 1.5 to 10.0 .mu.m thick polymer resin film.