JPS60121587A - Magnetic bubble memory element - Google Patents

Abstract

PURPOSE:To reduce the level difference of a soft magnetic substance pattern and to increase the transfer margin and accuracy by using a thermosetting film of heat resistant polymer resin as the 2nd insulated film and at the same time specifying the sloping angle at a level difference part of said insulated film. CONSTITUTION:The 2nd insulated film 9 is obtained by forming a conductor pattern 8 and coating a solution obtained by dissolving a prescribed amount of heat resistant polymer resin into a solvent with hardening through a heat treatment. In this case, the level difference due to the pattern 8 is greatly reduced on the surface of the film 9 by leaving the film 9 for a prescribed period of time after coating of said solution. Thus the film 9 can have a flat surface. Then the sloping angle theta is set at <=40 deg. at the level difference part of the film 9. As a result, the margin of a bias magnetic field is set at >=10%.

Description

[Detailed description of the invention] [Field of application of the invention] The present invention relates to magnetic bubble memory devices.

[Background of the invention]

Generally, a magnetic bubble memory element has a structure as shown in the first @. That is, on the magnetic III holding the magnetic bubble, the first insulation [2, conductor pattern 3.
A second layer 4, a soft magnetic material pattern 5 used for bubble transfer and detection, a protective film (not shown), etc. are sequentially laminated and deposited 1).

In such a conventional magnetic bubble memory element, LN
A part of the soft magnetic material pattern 5 is the conductive material pattern 3
As shown in FIG. 1, there is a step difference in the area where the bubbles overlap, which has the disadvantage of deteriorating the bubble operating characteristics. That is, if a sharp step as shown in FIG. 1 occurs in the soft magnetic material snow turn 5, this step causes an undesirable magnetic pole, and the transfer margin is significantly reduced. The problem caused by such a step becomes more noticeable as the bubble diameter becomes smaller, so in order to form a high-density magnetic bubble memory element, it is absolutely necessary to eliminate the step and flatten the soft magnetic material pattern. In particular, recently, in order to form fine patterns, conductor A-turns are formed by ion milling, and in this case, the slope of the side surface of the conductor pattern reaches as much as 80 degrees, so the above-mentioned step is It gets bigger and bigger.

In order to solve such problems, conventional methods (1) SOG (
(2) A method of applying a sensitive material using a crosslinking reaction caused by light irradiation has been proposed. However, with method (1).

There are problems such as poor alignment accuracy when creating a transfer pattern, and because it is an inorganic substance, defects occur in the formed film due to hydrolysis reaction. In method (2), the cured film is formed by light irradiation, so exposure.

In addition to the need for development, it is also necessary to pre-bake immediately after application in order for the sensitive material to adhere to the insulating film and make it easier to adhere to the insulating film. In order to prevent the cured film from deforming due to high heat, a plurality of processing steps are required, such as the need to perform post-baking after development, and there is a risk that accuracy may deteriorate during many steps.

[Object of the present invention] An object of the present invention is to solve the above-mentioned problems of the conventional magnetic bubble memory element, to reduce the level difference of the hard magnetic material pattern through simple processing, and to create a highly accurate magnetic bubble with a large transfer margin. An object of the present invention is to provide a memory device.

[Summary of the invention]

In order to achieve the above object, the present invention uses a thermosetting film of a heat-resistant polymer resin that undergoes a crosslinking reaction with heat (hereinafter referred to as a resin film) as at least the second insulating film, and The second insulating film is characterized in that the inclination angle at the stepped portion is formed to be 40 degrees or less.

[Embodiments of the invention]

The present invention will be explained in detail below.

FIG. 2 is a diagram for explaining one embodiment of the present invention,
As the first Zeroku I deposited on Garnet l-11!1,
5jO2RFi7 with a thickness of 200 nm, and the second insulating film 9 interposed between the conductive pattern 8 and the soft magnetic material pattern 10, a polyimide resin with a thickness of 300 nm r++, here polyimide-isoindoquinazoline dione. (Po1.yimi+1e -1sojnrl
A partial cross-sectional structure of a magnetic bubble memory device using a thermosetting film of ROQ former nazo1incLio+1 (hereinafter referred to as pH) is shown. (In addition.

An actual magnetic bubble memory device includes a substrate on which the garnet film 1 is adhered, a hard bubble suppression film, a protective film, etc., but since they are not directly related to the present invention, only one drawing is shown. In order to simplify the explanation and make it easier to understand, all illustrations are omitted. ) Above 1) I 1. In the I conversion 9, after forming the conductor pattern 8, a predetermined amount of 1) 11 is mixed with a solvent (for example, N-methyl 2-pyrrolidone and N,N dimethylacetamide (1=1)).
A liquid dissolved in a mixed liquid, etc.) is applied by spin coating, etc., and then heat treated to harden. It is formed by ``''.

The film thickness of the obtained 1111111@9 can be obtained by spin coating as 1) 1 m degrees; the desired thickness can be obtained depending on the number of rotations, for example, the thickness of 1111111@9 is 300 l) l 1m is cured 5, and a thermosetting IyA having sufficient properties as an insulating force for a magnetic bubble memory element is obtained.

Since the thickness of the redundant conductor pattern 8 is approximately 351) nm, the film thickness as the second insulating film is equal to the above-mentioned P1. If a SiO film of 300 nrn, which is the same as the T film, is deposited, as shown in FIG. 1, a sudden step will occur and the transfer margin will be significantly reduced.

However, if I"11 is used as the second insulating film, p
Since H is a liquid, it has the property of reducing the unevenness of the PTT film surface and making it flat. Therefore, if PT[ is applied by spin coating or other methods and left to stand for a predetermined period of time, as shown in FIG. The level difference on the surface is significantly reduced and becomes flat, and as a result, the level difference in the soft magnetic material pattern 10 is also significantly reduced compared to the case 7 shown in FIG.

In the present invention, the thickness of the PII film 9 is extremely important. If pHHBO2 is too thin, the effect of reducing the level difference will be insufficient, and in extreme cases, the conductor pattern 8
In this case, the insulation between the soft magnetic material pattern 10 and the soft magnetic material pattern 10 becomes poor. On the other hand, if it becomes too thick, the distance between the garnet film that holds bubbles and the soft magnetic material pattern becomes large, causing various problems in bubble detection.
It is necessary that the film IIX is within a predetermined range.

As shown in FIG. 3, when a P11 thermosetting film 9 having a thickness of 11 is formed on the first insulating TvA 7 and the conductor pattern 8, the inclination angle at the stepped portion is set to 0.

Of course, the smaller the inclination angle 0, the smaller the step difference, which is preferable as a magnetic bubble memory element.

As shown in Figure 4, the inclination angle is 0.
becomes larger and therefore becomes smaller.

However, as shown in FIG. 5, as the inclination angle f1 increases, the margin of the bias magnetic field becomes significantly smaller. Here, the bias magnetic field margin refers to the range of the external magnetic field that allows the bubble memory element to operate normally. In the magnetic bubble memory element, t? In this case, the external magnetic field is applied by a permanent magnet, but for reasons such as fluctuations in the magnetic field due to temperature fluctuations, the margin of the bias magnetic field needs to be 10% or more in practice.

The bias magnetic field margin is 1'0% or more in the fifth
As is clear from the figure, this is the case when the inclination angle O is less than 4 (bi), and under such conditions, lli@thickness of pH19 is
It is only when l: l Oram or higher that the 4th
It is clear from the figure.

However, the film thickness 11 of the film 9 is I l) O
If it becomes less than nn-, the insulation between the four-electric pattern and the soft magnetic pattern becomes poor, and for this reason, P'
The film thickness 11 of the l+ film 9 needs to be 100 old n or more.

On the other hand, a detector detects the presence of magnetic bubbles.

+: Since it is placed above +zrDg, if the distance between the garnet film that holds the magnetic bubble and the detector becomes too large, the output of the detector will drop significantly. Therefore, the distance between the garnet film and the detector needs to be less than a certain value, and therefore, in practical terms, the sum of the film thicknesses of the first insulating film 7 and the second insulating film 9 is + Must be less than 400 nrn.

In addition, the first insulating film 7 needs to have a certain thickness in order to relieve the stress of the garnet film that holds bubbles, but if the film is too thick, bubbles will be generated. The current required for this will increase significantly.

Therefore, the film thickness of the first insulation +m is I OQ-40Or
+m, and this film thickness range is
The material strength of the first insulating film S i (-, 1, is the same whether it is a heat-resistant resin or not. Therefore, the film thickness of the above PIIIA9 is at least 10Q
++m, Nt large 1, OOO-1,300,++
It is m.

FIG. 6 shows another embodiment of the invention. In this embodiment, a garnet film 11''2 [S
The first layer deposited (WA(S io , II
A) Since the above part of 12 coincides with the upper surface of the conductor pattern 13, it becomes a complete planar structure, and the second insulating film (PI'! film) 14 is deposited on it. The magnetic material pattern 15 does not have any level difference.

The first insulating film 12 is first deposited using a chemical vapor deposition method or the like on the conductor pattern 1', and then the conductor pattern 13 is deposited on the conductor pattern 1'. and 1
-・, SiO, Il at the first stage! After depositing on the entire surface, the S + C 12 on the conductive pattern 13 is removed by riff I-off, and is then formed. Shi, Kashi 5, Riff 1-
When turned off, the side surface of the conductor pattern 13 and 5iQ2
It is inevitable that voids will be formed between the membranes 12. If Si I-) 7 is used as the second insulating film 14, it is impossible to completely fill this void;
Using I] is highly preferred in order to form a perfect porcelain structure, since the voids are completely filled during the coating process.

Next, the formation of the bonding butt in the present invention will be explained. According to the present invention A1, a magnetic bubble memory element with a small step difference and a large operating margin can be obtained as described in item 1, but since the adhesiveness between the resin and the 8102 film is somewhat poor, the bonding pad is formed from the interface with the resin. There is a risk of peeling off.

Part 41. To prevent this, bonding paso 1-1
It is necessary that a resin film be present at . . . 7 to form a structure such as that shown in FIG. 7A'=e.

First, as shown in FIG. 7 and 8, Si('l, film 22,'-
Conductive path 23 consisting of A (1-(7+), PIl film 24
．． Permanent "1 I [11, mark i1" on the potresist pattern 26 in sequence.

-1: Using the photolithographic pattern 26 described above as a mask, the permalloy film 25 is etched as shown in FIG.
1. As shown in FIG. 7, a portion of the conductive path 21 and Sin, 11#!22 are exposed.

As shown in FIG.
5 is coated on the entire surface, a hole 27 reaching the barmaro-r film 25 is made, and a bodeff c-n pad 28 is formed by well-known bodging, as shown in FIG. 7C. A new structure can be obtained.

As is clear from FIG.
Moreover, Par 7 r, + I wA26ri + 1 step)
I l pIA24 Ni, Nittemeirushi, <Smallness 41. Therefore, an extremely reliable element j- can be obtained.

Note that there is a resin film under the bonding pad, and in order to avoid this, after forming the PIIg 24 on the first insulating film 22, the P11 film 2 is removed by normal etching.
It is also possible to remove the bonding butt part 4, the detector part, and the marker part for mask alignment. By doing this, the detector part is removed, so the distance between the detector and the magnetic garnet film becomes smaller. , there is an advantage that the detection output increases. Furthermore, by removing the mask alignment marker portion of the PTT film, the accuracy of mask alignment during photoetching of the soft magnetic film is improved.

That is, when performing mask alignment on the conductor pattern, there is a problem that 1) the presence of the 11 film makes the pattern edge unclear and reduces the accuracy of mask alignment, but the above method overcomes these drawbacks. To prevent. τ can be done.

For the sake of convenience, the above explanation is based on the case where 1) I is used as a heat-resistant polymer resin that is cured by heat, but 2 the material used and obtained in the present invention is 1) I
The pH value is not limited to 1, and the same effect as pH can be achieved by using other heat-resistant high-density resins.

In other words, the temperature during the creation of the magnetic bubble sled element is 150~:l! Since it reaches Q (+ ”(”,
The resin used in the present invention is required to be able to withstand the above-mentioned temperature, and a resin that is stable for a long time at a temperature of 2θO'Y'' is referred to as a heat-resistant polymer resin in this specification.

To reduce the level difference, the viscosity of the resin should be 200゜r, II
q or less, and it is also desirable that there be no deformation such as split t during curing, and it is desirable that the formed
It is also necessary that the dielectric strength voltage of the film be B+'V/l.

There are many heat-resistant polymer resins that satisfy the above conditions and can be used in the present invention, such as F) I above.
In addition to polyimide resins such as 1, epoxy resins, phenol resins, polycarbonate resins, polyamide/imide resins, 9 polyimide resins, etc. can be used, and one or more of these resins can be used. [Effects of the Invention] According to the present invention, at least the second insulating films may be used in combination.

A thermosetting film of a heat-resistant polymer resin is used, and this second
Since the inclination angle at the stepped portion of the second insulating film is formed to be 40 degrees or less, the second insulating film can be planarized and the bubble transfer margin can be increased by 1.

[Brief explanation of drawings]

FIG. 1 is a partial cross-sectional view for explaining the structure of the main part of a conventional magnetic bubble memory element, FIGS. 2 and 6 are partial cross-sectional views showing different embodiments of the present invention, and FIGS. FIG. 4 is a diagram showing the relationship between the thickness of the PTI film and the tilt angle, FIG. 5 is a diagram showing the relationship between the tilt angle and the bias magnetic field margin, and FIG. 7 is a diagram showing the process for forming the bonding pad in the present invention. It is a diagram. 1... Garnet film, 2.7, 12.22... First insulating film, 4.9, 14
．． 24...Second insulating film. 3.8.13.23... Conductor pattern. 5, to, 15.25... Soft magnetic material pattern. Figure 7 @ 2 Figure 3 Figure 4 PI (2 ash/L (9 m) Figure 1 Inclined needle θ0 illusion Figure 1

Claims (1)

[Claims] 1. A magnetic film that is laminated on a non-magnetic substrate and can hold the attached magnetic bubbles, a first insulating film, a conductive pattern,
In the magnetic bubble memory element comprising at least a second insulating film and a soft magnetic material pattern, the second insulation film R11
i! is a thermosetting film of a heat-resistant polymer resin, and the inclination angle at the stepped portion formed in the second insulating film is formed to be 40 degrees or less.