JPS59112485A - Preparation of magnetic bubble memory - Google Patents

Abstract

PURPOSE:To flatten a permalloy pattern of a gate part so as not to generate a step difference by using an inorganic film whose adhesive strength is good, as a spacer layer on an electric conductor, and executing an exposure and a development by utilizing a good positioning accuracy of a projection type exposer. CONSTITUTION:An electric conductor layer whose film thickness is hAngstrom is formed through the first spacer on a magnetic bubble crystal, it is formed at an electric conductor pattern 14 by a photolithographic method, subsequently, an inorganic insulating film is formed as the second spacer to the film thickness of >=hAngstrom by spattering, vapor deposition, a CVD method, etc., and next, by using a photoresist 16, patterning is executed so that the resist 16 is left only on the second spacer part 16 under which the electric conductor pattern does not exist, in the lower part of a permalloy pattern part 17 which crosses the electric conductor pattern 14, and thereafter, this second spacer layer is etched by depth of the same degree as hAngstrom , the resist 16 is peeled off, a permalloy film is formed on said layer, and subsequently, this permalloy film is formed to a desired driving pattern.

Description

DETAILED DESCRIPTION OF THE INVENTION (1) Technical Field of the Invention The present invention relates to a magnetic bubble memory device used as a storage device in an electronic computing device or a terminal thereof.

(2) Background of the technology Magnetic bubble utilization devices that use magnetic bubbles to store information, perform logical operations, etc. are nonvolatile, have high storage density, low power consumption, are small and lightweight, and have no mechanical components. Because it is a solid-state device that does not contain any metal, it has high reliability and is therefore expected to have a promising future as a large-capacity memory.

The memory element used in this magnetic bubble memory device is
For example, a thin film of magnetic garnet is formed as a magnetic bubble crystal by liquid phase epitaxial growth on a single crystal substrate of gadolinium, gallium, and garnet, and then a permalloy thin film is used to form a pattern of T-bars, 1d bars, 7 disks, etc. on top of the thin film to form bubbles. A propagation path is formed and the area where there is a bubble is
Information is recorded as 1.

In such a magnetic bubble memory, a bubble generator,
A function cell such as a transfer gate is constructed by combining a conductor pattern and a hermalloy pattern.

(3) Prior art and problems Figure 1 is a diagram showing an example of a function gate of a conventional magnetic bubble memory, where a is a plan view and b is a plan view of figure a.
-B sectional views taken along the line are shown. In the same figure,
1 is a magnetic bubble crystal, 2 is a spacer, 3 is a conductor pattern, 4 is a spacer, and 5 is a permalloy pattern.

In this function gate, since the permalloy pattern 5 is formed after the conductor pattern 3 and the spacer 4 are formed, the conductor pattern 3 causes a step at the arrow a portion, deteriorating the operating characteristics. For this reason, it is necessary to flatten the permalloy pattern, and currently the lift-off method and the method of using resin for the spacer are employed.

As shown in FIG. 2, in the lift-off method, first, when forming the conductor pattern 3 as shown in FIG. After the photoresist 6 is deposited to a thickness similar to that of the photoresist 6 and the spacer 4 on it is
Then, as shown in Figure d, a spacer 4' is further deposited, and a permalloy pattern 5 is formed thereon.

However, in this case, a gap 7 is likely to occur between the conductor pattern 3 and the SlO spacer 4, which causes distortion in the permalloy pattern and impairs the operating characteristics.

In addition, in the method using a resin spacer, as shown in FIG. 3, the permalloy pattern 5 is flattened by the resin layer 8, but if the resin is polyimide, there is a problem in adhesion, which may cause peeling of the permalloy layer. , it has the disadvantage of lack of reliability.

(4) Purpose of the Invention In view of the above-mentioned conventional problems, the present invention provides a method for producing a magnetic bubble memory that forms a permalloy pattern with flattened steps caused by a conductor pattern in a highly reliable manner without impairing operating characteristics. The purpose is to provide

(5) Structure and object of the invention According to the present invention, in a method for producing a magnetic bubble memory having a function gate formed by combining a conductor pattern and a permalloy pattern, the function gate is formed on a magnetic bubble crystal. 1st to
A conductor layer with a thickness of hA is formed through a spacer, and this is formed into a conductor pattern by photolithography, and then an inorganic insulating film is used as a second spacer by sputtering, vapor deposition, CVD, etc. to form a conductor layer with a thickness of hA or more. Then, patterning is performed using photoresist so that the resist is left only on the second spacer part where there is no conductor pattern underneath at the bottom of the permalloy pattern part that intersects with the conductor pattern, and then sputter etching, This second spacer layer is etched to a depth similar to hA by a dry process such as ion milling, the resist is peeled off, and a permalloy film is formed on it.Then, the permalloy film is formed into a desired driving pattern. This is achieved by providing a method for creating a magnetic bubble memory characterized by forming a magnetic bubble memory.

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

FIG. 4Bxg is a diagram for explaining the magnetic bubble memory manufacturing method according to the present invention. In the figure, 10 magnetic bubble crystals, 11 a first spacer made of SiO2, etc.
12 is a conductor layer using Al-Cu or the like, 13 is photoresist, 14 is a conductor pattern, 15' is 5102, 810,
5iaN4. A second spacer made of an inorganic insulating film such as Al2O3, 16 a photoresist, 17 a permalloy pattern, and 18 a protective film made of SiO2.

To explain the method of the present invention with reference to the drawings, first, as shown in Fig. A, 8102 is placed on the magnetic bubble crystal 10 as the first spacer 11.
1000^, and then Al as the conductor layer 12.
-Cu to 4000. Formed by A vapor deposition. Next, as shown in Figure b, a photoresist is applied, exposed and developed 7 times to form a pattern 13. Next, as shown in FIG. 0, the conductor layer is etched by ion milling and the resist is peeled off to form a conductor pattern 14.

Next, as shown in figure d, the 5I02 film 15 was heated to 400OA (j7
1. Sputtering is performed to a thickness greater than the film thickness of the body pattern 14). Next, as shown in Fig. e, a photoresist 16 is applied, and exposed and developed so that only the portions below the permalloy pattern on the conductor pattern of the gate portion, where there is no conductor pattern below, remain resist.

This part will be explained in more detail using FIG. 5. When forming a gate pattern as shown in FIG.
A resist pattern 16 is formed as shown in the figure. At this time, the resist is positioned so that the gap G is approximately 0 to 0.2 μm so that the resist does not cover the conductor pattern 14. The outer periphery of the permalloy pattern 17 that is not in contact with the conductive pattern 14 is approximately 1 μm larger than the resist pattern 16.
form. That is, a photomask is prepared in advance in this manner.

Next, as shown in Fig. 4 f, 8
The thickness of the 102 film 15 is equal to the thickness of the conductive pattern 14.
Etching is performed to approximately 0OA, and the resist is peeled off to form second spacers 15'. In this case, as shown in FIG. 5, since the gap is at most 0.2 .mu.m, this portion is hardly removed and there is no problem in planarization.

Finally, as shown in figure g, permalloy is vaporized at 400OA to form a driving pattern 17, and a protective film 18 is formed using SiO2.
is sputtered to a thickness of 1 μm.

In the magnetic bubble memory device produced in this manner, the permalloy pattern 17 at the gate portion has no step and is flattened, as shown in FIG. 4g.

Since an inorganic insulating material is used for the trench second spacer 15', the adhesion between the upper layer and the lower layer is also good. Furthermore, since the minor loose permalloy pattern is closer to the crystal substrate, the pattern becomes smaller and the driving magnetic field can be smaller when the density is increased.

(7) Effects of the Invention As explained in detail above, the magnetic bubble memory manufacturing method of the present invention uses an inorganic film with good adhesion as a spacer layer on a conductor, and uses the alignment accuracy of the recent projection exposure equipment. The difference in level caused by the conductor pattern is flattened by using the magnetic bubble width (±0.1 μm), which has a great effect in that a magnetic bubble memory with good operating characteristics can be obtained.

[Brief explanation of drawings]

Figure 1 is a diagram for explaining the function gate section of a conventional magnetic bubble memory, and Figure 2 is a diagram showing the resist lift,
FIG. 3 is a diagram for explaining the OFF method, FIG. 3 is a diagram for explaining the flattening method using resin, and FIGS. 4 and 5 are diagrams for explaining the method for producing a magnetic bubble memory according to the present invention. In the drawing, 10 is a magnetic bubble crystal, 11 is a first spacer, 12 is a conductor layer, 13 is a photoresist, 14 is a conductor pattern, 15 is an 8102 layer, 15' is a second spacer, 16 is a photoresist, and 17 is a conductor pattern. Permalloy pattern, 18 indicates a protective layer, respectively. Patent applicant Fujitsu Ltd. Patent agent Akira Aoki Patent attorney Kazuyuki Nishidate Patent attorney Yukio Uchida Patent attorney Akiyuki Yamaguchi 5th G) (b)

Claims (1)

[Claims] 1. In a method for manufacturing a magnetic bubble memory equipped with a function gate configured by combining a conductor pattern and a permalloy pattern, the function gate is formed by forming a conductor layer with a thickness hA on a magnetic bubble crystal via a first spacer. This is formed into a conductive pattern by photolithography, followed by sputtering, vapor deposition, C
hX using an inorganic insulating film as a second spacer by VD method etc.
The film is formed to the above thickness, and then patterned using a photoresist so that the resist is left only on the second spacer part below the permalloy pattern part that intersects with the conductor pattern and there is no conductor pattern under it, and then, This second spacer layer is etched to the same depth as hA by a dry process such as sputter etching or ion milling, the resist is peeled off, and a permalloy film is formed thereon, and this permalloy film is then driven as desired. A method for creating a magnetic bubble memory characterized by forming it into a pattern.