JPS59112480A - Magnetic bubble memory element - Google Patents

Abstract

PURPOSE:To obtain a large output signal even in case when a diameter of a bubble becomes small by reducing a spacing of a bubble detector part. CONSTITUTION:As for a detector part D0 of a magnetic bubble memory element, a spacer layer SP is removed partially, and the spacing becomes small. Therefore, a leakage flux quantity from a bubble, which exerts influence on the detector is increased, and even in case when a diameter of the bubble becomes small, a large output signal is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a magnetic bubble memory device, and more particularly to improving the output signal of a magnetic bubble detector.

[Prior art]

FIG. 1 is a diagram showing an example of the configuration of a magnetic bubble memory element. In the same figure, m is a minor loop that stores information, RML
is the read major line that transfers read information, WM
L is a write major line that transfers write information. R is a replicate gate that makes a copy of the information in the minor loop m on the read major line RML, and S is the copy of the information in the minor loop m and the write major line WML.
It is a swap gate that exchanges the above information. G is a bubble generator for writing new information, and D is a bubble detector for converting bubbles into electrical signals according to the present invention. GR is the guardrail and BP is the pounding pad.

FIG. 2 shows an example of the configuration of a puzzle detector. In the same figure,
St is an expander that expands the bubble into a string-like elongated bubble, and D is a bubble detector.

These patterns are formed from a soft ferromagnetic thin film such as Permalloy. Bubble detection is performed using the magnetoresistive effect. Constant current Id across the detector (referred to as detector current)
Let it flow. When the bubble B expanded into a string-like bubble by the expander St is transferred in the direction of arrow P and passes under the detector, the resistance Rd of the detector changes by ΔRd due to the magnetoresistive effect, and the detection An output signal of magnitude IdXΔRd is obtained at both ends of the device.

The currently produced IM bit bubble memory devices are 2
Although μm bubbles are used, the bubbles are expanded 500 to 800 times using a magnifier St to form string-like bubbles of 1 mm to 1.5 mm. Magnifier St.

The period λ of the detector is 10-20 μm, while the length L is 1-1.5 mm. The resistance R of the detector is 1 to 1.
5Ω, and the magnitude of the detector current Id is 3 to 4 mA.
Therefore, the magnitude of the output signal IdXΔRd is 4 to 6m
It is V.

Now, in the future, the bubble diameter d used in magnetic bubble memory devices will become smaller, and the memory capacity will become higher density and larger. When the bubble diameter d becomes smaller, the following problems arise.

FIG. 3 is a graph showing the result of examining the dependence of the output signal on the bubble diameter, with the bubble diameter d plotted on the horizontal axis. As described above, conventionally there was a problem that when the bubble diameter was reduced to about 1.5 μm, the output signal suddenly decreased.

[Purpose of the invention]

Therefore, an object of the present invention is to provide a bubble detector that can obtain a large output signal even when the bubble diameter becomes small.

[Summary of the invention]

In order to achieve this object, the present invention partially reduces the spacing of the bubble detector section.

[Embodiments of the invention]

The present invention will be explained in detail below.

The reason why the output signal becomes smaller as the bubble diameter d becomes smaller is that the leakage magnetic flux from the elongated string-shaped bubble B in FIG. be. Therefore, the following two methods can be considered to increase the output i.

(1) In Fig. 2, a method of increasing the length L of the detector, lengthening the string-like bubble, and increasing the amount of leakage magnetic flux.

(2) A method of increasing the amount of leakage magnetic flux from the bubbles by increasing the distance between the string-shaped bubble and the detector (referred to as spacing, which will be discussed later) using a small comb.

The present invention uses method (2) of these two methods.
- Yes. That is, it is intended to partially thin the spacing of the detector portion (the portion indicated by the dashed line in FIG. 1).

Prior to detailed explanation of the present invention, a conventional example will be explained first.

FIG. 4 shows a cross-sectional layer configuration diagram of a conventional magnetic bubble memory element. In the figure, LPE is a bubble magnetic film serving as a magnetic bubble medium, and bubbles with a diameter of about 2.0 μm are generated. On the bubble magnetic film LPE, there is a spacer layer Sp (usually about 1000A) formed by Sing, etc., and on this is an Au/
There is a conductor layer C (usually about 3500A) made of Mo or the like. On top of this is an insulating layer 2 (usually 0.3
On top of this is a transfer path layer Pr (usually about 4 μm) formed of permalloy, etc., which constitutes the puzzle transfer path and detector.
000 A8 degrees). Furthermore, there is a protective film layer Pa (usually about 10,000 A) made of SiQ, etc. on top of this, and a bonding pad layer Bp (usually about 2,000 OA) made of 4-At or the like on the top layer. There is.

FIG. 5 is a diagram showing an example of an embodiment according to the present invention,
FIG. 3 is a cross-sectional layer configuration diagram showing an example in which the spacing of the detector portion indicated by the dashed-dotted line in FIG. 2 is partially thinned.

In this figure, the same symbols as in FIG. 4 indicate the same things. By partially removing the spacer layer Sp under the detector section Do, the spacing of the detector section Do is thinned. Note that in this case, the step that occurs at the boundary where the spacer layer Sp is removed is planarized by the insulating layer thereon and does not cause any problem.

FIG. 6 is a diagram showing another example of thinning the spacing of the detector portion. The same symbols as in FIG. 5 indicate the same things. In this example, the insulating layer 2 under the detector section Do is removed. In this case, the detector spacing is 100
OA became too thin and caused a bubble transfer error.

The optimal value for spacing was 2000-aoooX. Furthermore, the step difference that occurs at the boundary where the insulating layer Z is removed is large, and if the transfer path layer Pr is overlapped with this portion, a step break will occur, which poses a problem.

FIG. 7 shows another embodiment of the present invention in which the spacing of the detector portion is reduced, which solves the above problem. In this figure, the same symbols as in FIG. 6 indicate the same things. This example is characterized in that the insulating layer is composed of two layers, the first and second layers Z+ and Zz, and the first insulating layer zI under the detector section DO is removed. In this case, the spacing of the detector is the thickness of the spacer layer Sp plus the thickness of the second insulating layer Z2, which is 2000 to 3000A KT.

Furthermore, the step that occurs at the boundary where the first insulating layer z1 is removed is planarized by the second insulating layer Z2 thereon and does not cause any problem.

〔Effect of the invention〕

As explained above, according to the present invention, by partially thinning the spacing of the detector section, even if the bubble diameter d becomes minute, the leakage magnetic flux from the bubble can be increased without reaching the detector, and the output can be increased. It is possible to prevent the signal from suddenly decreasing by 4.

[Brief explanation of drawings]

Figure 1 is a diagram showing an example of the configuration of a magnetic bubble memory element, Figure 2 is a diagram showing an example of the configuration of a magnetic bubble memory element.
The figure shows an example of the configuration of a bubble detector, Figure 3 is a graph showing the results of bubble diameter and output signal magnitude, Figure 4 is a cross-sectional layer configuration diagram of a conventional magnetic bubble memory element, and Figure 5 is FIGS. 6 and 7 are cross-sectional layer configuration diagrams of one embodiment of the present invention, and FIGS. 6 and 7 are cross-sectional layer configuration diagrams of other embodiments of the present invention. LPE...Bubble magnetic g, Sp...Spacer layer, C...Conductor layer, 2...Insulating layer, Pr
...transfer layer, DO...detector section, P8
...Protective film layer, Bp ...Ponding pad wide. o ” RJ U] ′- +-t N
○Wata V Palm (1

Claims (1)

[Claims] 1. A magnetic puzzle memory element in which the spacing of a bubble detector portion is partially reduced. 2. Claim 1 in which the spacer layer below the bubble detector is partially removed to partially reduce the spacing.
The magnetic bubble memory device described in .