JPS61104390A - Magnetic bubble memory element - Google Patents

Abstract

PURPOSE:To suppress stably an abnormal bubble with respect to a heat treatment, too, without deteriorating an operation margin even in case of a magnetic bubble memory element of a large storage capacity, by implanting an ion into a specified area under a prescribed condition. CONSTITUTION:An Nc<+> ion in implanted into a magnetic garnet single crystal thin film by 30-70keV acceleration energy, and 4.2X10<13>-14.3X10<13>Ne<+>/cm<2> ion implanting quantity. On the other hand, as for an ion implanting area, a relation of an ion acceleration energy and an ion implanting quantity of a logarithmic scale is between the lower limit boundary connecting by a roughly straight line each point of [30keV, 4.2X10<13>Ne<+>/cm<2>], [50keV, 7.0X10<13>Ne<+>/cm<2>], and [7.5keV, 10.5X10<13>Ne<+>/cm<2>] in the lower limit value, and the upper limit boundary connecting by a roughly straight line each point of [30keV, 5.7X10<13>Ne<+>/cm<2>], [50keV, 9.5X10<13>Ne<+>/cm<2>], and [75keV, 14.3X10<13>Nc<+>/cm<2>] in the lower limit value. By this correct condition and a correct area for suppressing an abnormal bubble, an operation margin is not deteriorated even in case of a large capacity element of 4M bit, etc., and the abnormal bubble can be suppressed stably with respect to a heat treatment.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a high storage density magnetic bubble memory device having a storage capacity of 4 Mbits per chip (approximately 1 cm), and particularly to The present invention relates to a magnetic bubble memory element in which abnormal bubble generation is suppressed by implanting Ne ions into a magnetic garnet single crystal thin film, which is a storage medium, under specific conditions.

[Conventional technology and its problems]

Conventional methods for suppressing abnormal bubbles in crystal thin films for magnetic bubble memory devices are as follows: In a magnetic garnet single crystal thin film of 1 Mbit per chip (approximately 1 cm), abnormal bubbles can be suppressed under implantation conditions of approximately 50 keV and 7 cm of 1 xio Ne. It was suppressed. However, 1 chip (about 1 cm)
), a crystalline thin film with a large storage capacity of 4 Mbit per
When processing under the above conditions, the operating margin becomes smaller,
(K, Yamagishi et al: Tra
ns, Magn MAG-1915+ 2. 1853 (1983)) Also 50ke V,
~5 x 10 Ne 7cm has the disadvantage that abnormal bubbles occur when heat treated at 300°C or higher.

The technical problem of the present invention is to solve such problems in the conventional method of suppressing abnormal bubbles by ion implantation, and to solve the problem of suppressing abnormal bubbles by, for example, magnetic garnet of a storage medium having a large storage capacity of 4 Mbits per chip (approximately 1 cm). The object of the present invention is to provide optimal ion implantation conditions for suppressing abnormal bubbles in single crystal thin films by ion implantation.

[Means for solving problems]

The technical means of the present invention taken to solve this problem is to accelerate Na ions into a magnetic garnet single crystal thin film that generates magnetic bubbles with an ion acceleration energy of 30 to 7.
5 keV, ion implantation dose 4.2 Xl013 +
Within the range of 2 to 14.3 X 10 Ne/cm, and the ion, (50 KeV, 7.0 X 10"N
e"7cm") Oyohi (75KeV, 10.5 x
1013Ne"/cm"J points are connected with almost straight lines at the lower limit and at the upper limit (30Ke V, 5.71
3 士XIONe /cX'J, (50Ke V, 9.5
10”Ne”/c+”.

and (75Kev, 14.3 x 10'3N
A configuration is adopted in which ions are implanted within a specific region between the upper limit boundary, which is formed by connecting each point of e"7 cm" with a substantially straight line.

That is, by setting the amount of ion implantation for suppressing abnormal bubbles within a specific range, the operating margin of the memory is not degraded, and abnormal bubbles are not generated again due to heat treatment.

[Effect]

According to this technical means, as the ion implantation amount increases, the hard bubble suppression effect improves, but the bias margin width significantly decreases beyond a certain ion implantation amount. Furthermore, the effect of suppressing hard bubbles during heat treatment during manufacturing of the magnetic bubble element is better as the amount of ions implanted is larger. Taking all of these conditions into account, the conditions for implanting Ne ions into the single crystal thin film of magnetic gas nanotubes, which will be the magnetic bubble material, are as follows: ion acceleration energy: 30 to 75 ke V, ion implantation amount: 4.2
The ion acceleration energy and the ion implantation amount on a logarithmic scale are within the range of C13KeV, 10.5X10'3Ne/c+m, and 10.5X10'3Ne/c+m.
cm”l each point approximately directly and (75Ke V, 1
A configuration in which ions are implanted within a specific region between the upper limit boundary formed by connecting each point of 4.3×10I3Ne''/cm' by a substantially straight line is effective.

〔Example〕

Next, how the method of suppressing abnormal bubbles by ion implantation according to the present invention is actually implemented will be explained using examples.

Crystal thin film (YSmLuCa) for bubble memory devices with a storage capacity of 4 Mbit per l chip (approximately 1 cm)
The ion implantation dose dependence of the abnormal bubble suppression effect in 3 (GeFe) s Otz is as shown in FIG. 1, and abnormal bubbles are suppressed in the region where ΔHa is ~20e or less. Here, ΔH is the maximum value of the variation in the bubble extinguishing and demagnetizing field (Ho) when bubbles are created by cutting striped magnetic domains in a crystal thin film with a pulsed magnetic field.

Ho min is the bubble H, which disappears in the lowest magnetic field,
If the HO of the bubble extinguished by the highest magnetic field is H6max, then ΔHo=HoIllax-H(Imin).In other words, the smaller ΔH, the smaller the hardness of the bubble, and the better the magnetic bubble material.First In the figure, abnormal bubbles are suppressed and the ion implantation dose starting at 3f2 is 50keV, 4xtoNe
It is 7cm.

On the other hand, the bias margin 3f width of the bubble memory device is 50keV, 4X1ONe as shown in FIG.
/cm, the margin width becomes 500e (maximum), and this decreases sharply with an injection amount of 14.
With the above, it becomes less than 1/2.

By the way, as shown in FIG. 6, the magnetic bubble element is GG
A bubble material consisting of an LPE film 2 is grown on a G substrate l, and on top of it an insulating film 3 such as 5i02, a conductor pattern 4 such as aluminum, and an insulating resin layer 5.5f02 layer 6 called PLO3 (polyladder organosiloxane resin). , a permalloy pattern 7, and a protective PLO3 layer 8 are formed in this order. Since heat treatment at about 350 to 400° C. is required to harden the layer made of PLO3, it is necessary to check in advance whether hard bubbles will occur due to this heat treatment.

15 S 2 Therefore, when a crystal treated with an ion implantation amount of 50 ke V and 5 x to Ne 7 cm was heat-treated at a temperature of 300°C, abnormal bubbles were generated after about 10 hours of heat treatment, as shown in Figure 3. In the above heat treatment, abnormal bubbles are generated in about 1 hour. At 500°C, hard bubbles are generated within 30 minutes. Here δ(Δ
Ho) is the value obtained by subtracting ΔH0 before heat treatment from ΔHO after heat treatment.

Further, FIG. 4 shows the results of investigating the occurrence of abnormal bubbles due to heat treatment by varying the amount of ion implantation. Here, the heat treatment temperature is
The temperature was set at 500°C, which was slightly higher than the curing temperature for the PLOS layer. According to Figure 4, 50ke V, 713
It can be seen that in the crystal treated under the ion implantation conditions of 2XIONe/c+m, abnormal bubble generation is completely suppressed even after heat treatment at 500°C. 50ke V, 6X1O
Under the ion implantation condition of 7cm2 of Ne, Hk is 2971
In the 0 e sample, bird bubbles were generated within 1 hour.

As mentioned above, when manufacturing a bubble memory device, 35
This heat treatment effect is important because heat treatment at 0 to 400°C is required.

The ion acceleration energy varies depending on the film thickness of the bubble material 2 in Fig. 5, but it is 4M per chip (approximately 1 cm2).
2μ or less (2~
For a film thickness of about 1 pII), ion acceleration energy of about 75 keV or less is preferable.

The table below shows the relationship between the ion implantation amount and the ion acceleration energy, which completely suppresses the generation of abnormal bubbles even in heat treatment at 500°C.

Table This is illustrated in Figure 5, where points a to f are the upper limit values, point g-1 is the lower limit value, and in the specific area (shaded area) connecting these points, abnormal bubbles appear even after heat treatment at 500°C. A magnetic bubble memory element having a magnetic garnet single-crystal thin film without the occurrence of is obtained. In addition, outside of this specific area, 4
Abnormal bubbles occur during heat treatment at temperatures below 00°C.

As mentioned above, the effect of suppressing abnormal bubbles is sufficient.
Maintains a practical operating margin as a bubble memory,
In addition, as a result of examining the ion implantation region in which abnormal bubbles do not occur again due to heat treatment in FIGS. 3 and 4,
The conditions that almost satisfy all the requirements are that the ion acceleration energy is in the range of 30 to 75 kecm2, and the relationship between the ion acceleration energy and the ion implantation amount on the logarithmic scale is at the lower limit (30 Ke V, 4.2 x 10 “N.E.
"/cm'), (50Ke V, 713 + , oxto Ne /cm") and (75Ke V,
10.5
eV, 5.7 x 10"Ne+/cn"), [50K
The abnormal bubble suppression processing condition was determined to be within a specific region between the upper limit boundary connecting the points of e V, 9.5×10 Ne /cIII211 and (75 Ke V, 14.3×1ONe /ca”) with a substantially straight line.

〔Effect of the invention〕

As described above, according to the present invention, ion acceleration energy:
30~75keV, ion implantation amount 4.2Xl0
Within the range of 73 f 2 to 14.3 × 10 Ne/cm and the 3 f relationship between the ion acceleration energy and the ion implantation amount on a logarithmic scale is at the lower limit (30 Ke V, 4.2 × 10
Ne/C-? ), (50Ke V,?, OX 1d3
Ne”/cm”l and [75KeV, 10.5X
The lower limit boundary connecting each point of 10'JN'e"/cm"l with an almost straight line and the upper limit value (30Ke V, 5.7
X 10”Ne+/ (ゐ, (50KeV, 9.5 x
10"Ne"/・me and (75Ke V, 14.
By implanting ions within a specific area between the upper limit boundary, which connects each point of 3 x 10'3 Ne+/cm'') with a nearly straight line, a magnetic Also in the bubble memory element, abnormal bubbles can be suppressed stably even under heat treatment without deteriorating the operating margin.

[Brief explanation of the drawing]

Figure 1 is a characteristic diagram showing the dependence of abnormal bubble suppression on the ion implantation amount, Figure 2 is a characteristic diagram showing the dependence of the bias margin on the ion implantation amount, and Figures 3 and 4 are the occurrence of foreign bubbles due to high temperature storage. FIG. 5 is a characteristic diagram showing the relationship between ion acceleration energy and ion implantation amount, and FIG. 6 is a sectional view showing the layer structure of the magnetic bubble element. In the figure, 2 is a bubble material made of LPE film, 4 is a conductive pattern, and 5.8 is PLO3! , 7 indicate permalloy patterns, respectively. Patent Applicant: Fujitsu Limited Agent, Patent Attorney, Minoru Aoyagi (90) l (/-/人-Z8f80e) 41 +2 (Hk-2ri730e) Is (t-t* -zsqq oe) Me: ion direction χ spear cattle 3θkeV3xπ-~bi 〃c/, /Xnon 2-Town ＾＾斂しにTwo?Monpi L well 4 (Hk -286θ
^O Mu: Aeon 2shi Njokot: 5OkeTr,'l! ;x
l(1'N//cf+: Chi ta,
/ x IO'W/cf Fig. 4 +1: #S CHd -294/ Da),:
#6CH4, -Zri7/ Oe) Zogi straddle ff'l (Darkness 5th @ E (JeV)

Claims (1)

[Claims] N in a magnetic garnet single crystal thin film that generates magnetic bubbles.
Ion acceleration energy for e^+ ions: 30-75ke
V) Ion implantation amount: 4.2×10^1^3~14.3×
Within the range of 10^1^3Ne^+/cm^2, and the relationship between the ion acceleration energy and the ion implantation amount on a logarithmic scale is at the lower limit [30 KeV, 4.2 x 10^1^
3Ne^+/cm^2], [50KeV, 7.0×10
^1^3Ne^+/cm^2) and [75KeV, 1
0.5×10^1^3Ne^+/cm^2] is connected with an almost straight line, and at the upper limit [30Ke
V, 5.7 x 10^1^3 Ne^+/cm^2], [5
0KeV, 9.5×10^1^3Ne^+/cm^2]
and [75KeV, 14.3×10^1^3Ne^+
/cm^2] is formed by implanting ions within a specific region between the points and the upper limit boundary connected by a substantially straight line.