JPS62217486A - Manufacture of magnetic bubble memory chip - Google Patents

Abstract

PURPOSE:To improve bubble transfer characteristics by removing the surface part of an insulating layer between layers which swells because of a conductor pattern and flattening a soft magnetic pattern. CONSTITUTION:An insulating layer 2, the conductor pattern 3, and the interlayer insulating layer 3 are laminated on a bubble crystal layer 1 and a swelling part 6 is exposed to form resist 7. Then, plasma etching is performed by a parallel flat plate type dry etching device to remove the swelling part 6 and flatten the interlayer insulating layer 4, and then resist 7 is removed by ashing. Then, a 'Permalloy(R)' pattern 5 is formed on the surface of the interlayer insulating layer 4 to obtain a chip with improved operation margin characteristics. Consequently, the operation margin characteristics at the intersection part of the conductor patterns are widened and the operation margin characteristics at a nonintersection part become nearly equal, so that a high- density bubble memory with a wide operation margin is realized.

Description

[Detailed Description of the Invention] [Summary] The present invention removes the surface portion of the interlayer insulating layer raised by the conductor pattern of a magnetic bubble memory chip, and flattens the surface of the interlayer insulating layer on which the soft magnetic pattern is formed. ,
This flattens the soft magnetic pattern and improves bubble transfer characteristics.

[Industrial application field]

The present invention relates to a method of manufacturing a magnetic bubble memory chip.

Bubble memory is also used in various devices such as office automation equipment, and its usage tends to increase year by year.

This type of bubble memory is now commercialized with a capacity of 4 Mbit, and one with a capacity of 16 Mbit is also being researched and developed.

Such high-density bubble memories are realized using bubbles with submicron diameters, but as the bubbles become smaller, the operating margin tends to deteriorate.

Therefore, it is desired to realize a high-density bubble memory with a wide operating margin.

B2- [Prior Art] FIG. 3 (b) is a sectional view of a major transfer path portion in a conventional magnetic bubble memory chip.

In the figure, 1 is a bubble crystal layer made of gadolinium-gallium-garnet etc. formed on a non-magnetic garnet substrate by liquid phase epitaxial growth, 2 is an insulating layer made of 3402 etc. formed by sputtering on bubble crystal Nl, 3 is a conductor pattern for bubble control made of Au, etc. that constitutes a functional gate such as swap or replicate, and 4 is a heat-resistant resin such as PLO3 (Poly Ladder Orga) siloxane resin applied for the purpose of flattening the conductor pattern 3. An interlayer insulating layer formed by thermosetting, 5 a permalloy pattern made of a soft magnetic material for bubble transfer, and 6 a raised portion of the interlayer insulating layer N4 formed by the conductor pattern 3.

Unlike the major transfer path portion, FIG. 3 has an overlapping portion between the conductive pattern 3 and the permalloy pattern 4 as shown in FIG. fb1.

In the past, (a) interlayer insulation N using resin as shown in the figure
After flattening the conductor pattern 3 in step 4.

(b) As shown in the figure, a permalloy pattern 4 was formed, and then a protective layer (not shown) was coated.

[Problem that the invention seeks to solve]

Conventionally, considerable flatness can be achieved by using the interlayer insulating layer 4, but the raised portions 6 cannot be completely eliminated, and the permalloy pattern 5 has a step difference as shown in the figure, which deteriorates the bubble transfer characteristics.

Therefore, as shown in FIG. 4, the operating margin characteristic A at the intersection with the conductor pattern has a narrower margin width than the operating margin characteristic B at the area without intersection with the conductor pattern.

Furthermore, Fig. 4 shows the operating margin in the relationship between the bias magnetic field and the drive magnetic field when the chip shown in Fig. 3 is assembled into a memory device by combining it with a bias magnet, a drive coil, etc., and the bubble diameter in this case is It is about 1.3 .mu.m, and the batten period of the permalloy pattern is about 4 -m.

Such an operating margin tends to deteriorate further as the bubble diameter becomes smaller.

rLJIIf Means for Solving Point 1] The present invention aims to solve the above-mentioned conventional problems.

A magnetic bubble memory in which the soft magnetic pattern is formed on the interlayer insulating layer, which includes a step of removing and flattening the raised part of the interlayer insulating layer where the conductor pattern is located after forming the interlayer insulating layer and before forming the soft magnetic pattern. Provided a method for manufacturing chips.

[Effect]

Since the process of removing the raised portions allows the conductor pattern to be almost completely flattened, the permalloy pattern has no steps and improves bubble transfer characteristics.

〔Example〕

FIGS. 1A to 1E are diagrams illustrating the method of manufacturing a magnetic bubble memory chip of the present invention, and are sectional views of the gate portion in the major transfer portion as in the conventional method.

In the figure, numerals 1 to 6 indicate the same structure as the conventional one, and 7 indicates a resist for removing the raised portion.

The process of this example is as shown in Figure 81, after laminating the insulating layer 2, conductor pattern 3, and interlayer insulation N4 on the bubble crystal Fil, (b) applying the resist 7 so that the raised portion 6 is exposed as shown in the figure. After that, plasma etching is performed using a parallel plate type dry etching device to remove the raised portion 6 and flatten the interlayer insulating layer 4 (Figure (C)).Then, the resist 7 is ashed and removed. (As shown in figure d1,
Thereafter, a permalloy pattern 5 is formed on the surface of the interlayer insulating layer 4 (a magnetic bubble memory chip according to the present invention as shown in FIG. 81 is obtained).

FIG. 2 shows the operating margin when the chip shown in FIG. 1 is assembled into a bubble memory device.

This is a measurement result under the same conditions as in Fig. 4.

In the present invention, the operating margin characteristic A at the intersection with the conductor pattern is widened and becomes almost equal to the operating margin characteristic B at the section without intersection with the conductor pattern.

=6- [Effects of the Invention] According to the present invention described above, a high-density bubble memory with a wide operating margin can be realized, and its practical effects are remarkable.

[Brief explanation of drawings]

Figure 1 (al to tel is a cross-sectional view showing the manufacturing process of the present invention, Figure 2 is an operating margin characteristic diagram of the bubble memory device according to the present invention, Figure 3+a) (bl is a cross-sectional view showing the conventional manufacturing process. 4 are operating margin characteristics diagrams of conventional bubble memory devices. [Explanation of symbols] 1-.-111 Bubble crystal layer. 2-1-- Insulation. 3-1-- −−− Conductor pattern. 4 −−−−−−−1 Interlayer insulating layer. 5 −・−・−Soft magnetic pattern. 6 −−−−−−−−1 Raised part. 4θ 5θ lθ 7θ 5R-rθe) Invention 1B Cross-sectional view showing the manufacturing process of the present invention Figure 2

Claims (1)

[Claims] A bubble control conductor pattern is formed on at least the magnetic bubble crystal layer via an insulating layer, an interlayer insulating layer made of an insulating resin material is formed on the conductor pattern, and a plurality of conductor patterns are formed on the insulating layer. In a magnetic bubble memory chip on which a soft magnetic pattern for bubble transfer is formed, after forming the interlayer insulating layer and before forming the soft magnetic pattern,
A magnetism comprising the step of removing and flattening a raised part of the interlayer insulating layer where the conductor pattern is located, and the soft magnetic pattern is formed on the surface of the interlayer insulating layer including the removed part. Method of manufacturing bubble memory chips.