JPS61104482A - Preparation of magnetic bubble memory element - Google Patents

Abstract

PURPOSE:To convert the defect arising from the stain sticking to the surface of a wafer to a 'drop-out' defect of a soft magnetic film which is a good defect by forming a soft magnetic pattern by a lift-off method. CONSTITUTION:A polyimide layer 12 and an Al film 13 are formed on a crystal 10 for a valve formed with a spacer 11 and the film 13 is etched with a resist pattern 14 as a mask to form an Al pattern 13a. The layer 12 is then etched with the pattern 13a as a mask to form a nonmagnetic pattern 16 consisting of Al and polyimide resin and thereafter a 'Permalloy(R)' film 17 as the soft magnetic film is formed over the entire surface. The resin 12 is finally etched away, by which the Al film 13 and 'Permalloy(R)' film 17 thereon are removed as well and the intended 'Permalloy(R)' pattern 18 is formed. The point where there is the stain 15 is converted to the 'drop-out' defect 19.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a magnetic bubble memory element used in a storage device such as an electronic computing device, and particularly relates to a method for manufacturing the same.

In magnetic bubble memory devices, the storage density is becoming more advanced due to the recent increase in the amount of information and the demand for miniaturization of devices. As density increases, defects in permalloy patterns due to contamination during the manufacturing process have become a bigger problem than in the past. Permalloy pattern defects include "chips" and "residues." When forming patterns using conventional technology, "chips" occur due to resist pinholes and peeling, and "residue" defects occur due to dirt such as fine particles. was. Comparing both numbers, “remaining”
It has been empirically shown that there are an overwhelming number of defects, and that "remaining" defects affect not only the defective minor loop but also other good loops, making them more malignant defects than "chip defects." was.

[Conventional technology]

The conventional method for manufacturing a magnetic bubble memory element is to form a permalloy film (soft magnetic film) 3 on a bubble crystal 1 through an insulating layer 2 such as Sing, and then to deposit a resist on top of the permalloy film 3. After creating pattern 4, as shown in Figure 3,
Ion etching was performed using the resist pattern 4 as a mask to create a permalloy pattern 5.

[Problem that the invention seeks to solve]

The above method has a problem in that when dirt 6 is present on the permalloy film 3 as shown in FIG. 3, the permalloy film 3 in that area remains unetched, resulting in "residue" defects 7.

[Means for solving problems]

The present invention provides a method for producing a magnetic bubble memory element that solves the above-mentioned problems.The method includes forming a non-magnetic layer on a bubble crystal, and then coating a photoresist on the non-magnetic layer to form a resist. A pattern is formed, then the nonmagnetic layer is etched using the resist pattern as a mask to form a nonmagnetic pattern, a soft magnetic film is formed on the entire surface, and the nonmagnetic pattern is etched to form the nonmagnetic pattern. A method of manufacturing a magnetic bubble memory element is performed, which is characterized in that a soft magnetic pattern is formed by removing a soft magnetic film thereon.

[For production]

The method for producing the magnetic bubble memory element is to form a non-magnetic pattern, further form a soft magnetic film over the entire surface including the non-magnetic pattern, and then etch the non-magnetic pattern to remove the non-magnetic pattern and the soft magnetic film over the non-magnetic pattern. By removing the magnetic film and forming a soft magnetic pattern, defects caused by dirt adhering to the wafer surface can be turned into benign defects such as "chip" defects in the soft magnetic film.

〔Example〕

Hereinafter, the present invention will be described in detail with reference to the drawings.

FIG. 1 shows a process diagram for explaining one embodiment of the present invention. In the figure, 10 is a bubble crystal, 11 is a spacer, 12.13 is a non-magnetic layer, 12 is a polyimide resin layer, and 13 is a he! 14 is a resist pattern, 15 is dirt (fine particles), 16 is a non-magnetic pattern, 17 is a permalloy film, 18 is a permalloy pattern, and 19 is a permalloy defect.

In this embodiment, as shown in FIG. 1a, S
On the bubble crystal 10 on which the iO□ film is formed, a polyimide layer 12 (with a thickness of approximately
A β film 13 (thickness: approximately 500 mm) is formed by vapor deposition thereon, and a resist pattern 14 is formed thereon by a photoresist method. Next, as shown in figure b
The film 13 is etched by chemical etching or ion etching to form an Al pattern 13a. Then C
As shown in the figure, the polyimide resin layer 12 is etched with 0□ plasma using the L pattern 13a as a mask to form a nonmagnetic pattern 16 made of Al and polyimide resin. Next, as shown in FIG. d, permalloy as a soft magnetic material is deposited on the entire surface to form a permalloy film 17. Finally, as shown in figure e, the polyimide resin in the non-magnetic pattern 16 is
The polyimide resin 12 is removed by plasma etching. At this time, the i film 13 and permalloy film 17 on the polyimide resin 12 are also removed, and the desired permalloy pattern 18 is formed.

In this case, even if there is dirt 15 as shown in Figure 1a,
As shown in Figure C, a non-magnetic pattern 16 is formed under the stain 15, and after forming a permalloy film 17, the non-magnetic pattern 1 is
When the stain 15 is removed by etching, the area where the stain 15 was left becomes a "chip" defect 19, as shown in Figure e. As described above, according to this embodiment, what would otherwise be a "remaining" defect under the conventional method can be made into a good "chipping" defect.

Next, an application example is shown in FIG. 2 to show other advantages of the present invention. In FIG. 2a, the polyimide resin 12 is over-etched during 0□ plasma etching, creating an undercut under the aluminum pattern 13a, making the permalloy pattern 18 thicker, and narrowing the gap. Further, in FIG. 2, a permalloy pattern 18 is formed directly on the bubble crystal 10. It is difficult to form permalloy patterns directly on crystals using conventional methods.

This is due to the low selective etching properties of permalloy and crystals with respect to ion etching.

That is, when etching permalloy, there is a risk that crystals may also be etched. According to the present invention, this problem does not occur because there is no need to etch the permalloy.

〔Effect of the invention〕

As explained above, in the method for producing a magnetic bubble memory element of the present invention, a permalloy pattern is formed by the lift-off method, so defects caused by dirt that adheres to the wafer surface during the process are treated as benign defects, while permalloy defects are treated as defects. be able to. Therefore, the effect of contributing to yield improvement is significant.

[Brief explanation of drawings]

FIG. 1 is a diagram for explaining an embodiment of the method for producing a magnetic bubble memory element of the present invention, FIG. 2 is a diagram for explaining an application example of the method for producing a magnetic bubble memory element of the present invention,
FIG. 3 is a diagram for explaining a method of manufacturing a conventional magnetic bubble memory element. In the figure, 10 is a bubble crystal, 11 is a spacer, 12 is a polyimide resin layer, 13 is an A1 film, 14 is a resist pattern, 15 is dirt, 16 is a non-magnetic pattern, 17 is a permalloy film, 18 is a permalloy pattern, and 19 is a permalloy pattern. Each permalloy defect indicates a defect.

Claims (1)

[Claims] 1. A non-magnetic layer is formed on the bubble crystal, and then a resist is applied on the non-magnetic layer to form a resist pattern,
Next, the non-magnetic layer is etched using the resist pattern as a mask to form a non-magnetic pattern, and after a soft magnetic film is formed on the entire surface, the non-magnetic pattern is etched to remove the soft magnetic film along with the non-magnetic pattern. A method for producing a magnetic bubble memory element, characterized by forming a soft magnetic pattern by removing. 2. The non-magnetic layers can be selectively etched with each other.
A method for producing a magnetic bubble memory element according to claim 1, characterized in that the magnetic bubble memory element has a two-layer structure using different materials. 3. The method of manufacturing a magnetic bubble memory element according to claim 2, wherein a highly heat-resistant resin is used as one of the nonmagnetic layers, and oxygen plasma is used as the etching means. 4. The method for producing a magnetic bubble memory element according to claim 2, wherein a silicon compound such as SiO_2 is used as one of the nonmagnetic layers, and fluorine-based plasma is used as the etching means.