JPS6261310A - Manufacturing magnetic device having garnet thin film containing bismuth - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (1) Technical Field of the Invention The present invention relates to a method for manufacturing a magnetic bubble device, which involves liquid phase epitaxial growth of a bismuth thin film containing all garnet.

(2) Background of the Technology The development of magnetic bubble devices has reached the stage of commercial use, particularly in storage devices capable of sequential retrieval in communications and data processing equipment.

Magnetic bubble devices typically consist of a flat diamagnetic substrate of gadolinium-gallium garnet Qd3GaaO+2 and a layer of magnetic garnet material deposited by epitaxy thereon, the easy magnetization direction of which is perpendicular to the layer. It is composed of When a suitable magnetic field is applied parallel to said direction, the layer can maintain small regions called bubbles, which are magnetized in a direction opposite to the direction of the applied magnetic field. The ideal region has a precise cylindrical shape and extends from near the surface of the magnetic thin film to near the interface between the substrate and the thin film. The diameter of the bubble is approximately equal to the thickness of the thin film.

The operation of the device primarily consists of the generation, movement, and detection of magnetic bubbles, the movement of which can occur, for example, in a magnetic layer or in a pattern with locally confined magnetic properties in a thin film.
1 of m'l"echnical Journal)
Bohenk (A.
, H, Bobeck) et al. K 7:y'' current 7
Access Magnetic Bubble Circuit” (('urrent Acc
essMagnetic Bubble C1rcui
t3) along a path or track defined by a conductive layer.

A liquid phase epitaxy method is suitable for depositing a magnetic garnet layer on a substrate, and this method was described, for example, in May 1974 by Rupinstein (HoJ).
U.S. Patent No. 3.790.40 issued to
As disclosed in No. 5, the garnet component in the melt can be grown with good control.

The properties of the formed layer, such as thickness, defect density, magnetization, coercivity, anisotropy field, and bubble diameter, stability, and mobility, depend on the growth conditions; for example, Nan et al. bath melt components, growth temperatures and growth procedures as disclosed in the following publications:

AIP Newsletter (AIP ('onference pro)
ceedings) published in 1974, Volume 10, pages 255-270 (S, L.

“Dynamics of LPE growth and its influence on magnetic properties” (BIank) et al.
Growth and its Influence
On Magnetic properties).

Journal of E1ectroche
micalSociety, 1976, vol. 123,
"Preparation and properties of magnetic garnet thin films containing divalent and trivalent ions" by Blank (S, L, Blank) et al.
preparation and properties
of Magnetic Garnet Films
Containing Divalent and '
17 etravalent) ons), l TEEE Bulletin on Magnetism (TEEE Trans-a
197 of ctions on magnetics)
Blank (S.

“The Effect of Melting Components and Flux Spin-Off from Lutetium in LPE Garnet Thin Films” by L. Blank et al.
Melt Composition on the Cu
rie Temperature and )'lux
5pin-Qff from Lutetium
Containing LPE carnet Film
s).

As magnetic device technology moves toward higher bit densities, changes in the details of the layer structure result. In particular, the thickness of certain layers has become thinner. This can be seen, for example, in the Journal of Applied Physics.
(Applied physics) 1979 3
Monthly issue.

5(), pages 2155 to 2160, by Blank et al.
Design and development of single layer, ion-implantable microbubbles 'fi' for magnetic bubble devices
nd Development o(Single L
ayer, Jon-Implantable 3ma
l113ubble Materials for
This is shown in a paper called Magnetic Snake.

Of recent interest is the nf? given to Parkstresser (G, W, Berkstresser) et al., dated 8u23/1983. , as disclosed in U.S. Pat. No. 4,400,445, directed to epitaxial growth from a melt consisting of PbO--V2O, a flux component.

The content of bismuth in the magnetic garnet fiber is 1
December 6, 983 Reflow (R, C0Le C
U.S. Patent No. 4.419.41, issued to
7 has been found to be beneficial.

(3) Construction of the Invention A magnetic bubble device consisting of a garnet layer or thin film containing bismuth is formed on a substrate by a method of epitaxially growing the entire layer. Growth occurs in a melt consisting of flux and garnet components.

According to the invention, the fluxing agent preferably consists of lead oxide, bismuth peroxide and, as additional fluxing component, a component chosen among vanadium oxide, tungsten oxide, molybdenum oxide and chromium oxide. According to the present invention,
The presence of the additional flux component gives a large magnetic anisotropy to the supercooling temperature of the melt.

The preferred amount of additional oxide ranges from 1 to 20 mole percent, the former value being for the effect on supersaturation to be clear, and the latter value being determined from melt stability considerations. It is. A roughly preferred range in these respects is 3 or preferably 5.
to 15 mole percent (range V2O., W
The amount K of O,, MOO, and CrO3? However, such oxides partially dissociate at high temperatures. pb.

Suitable ranges for B'203 are from 50 to 98 mole percent and from 1 to 30 mole percent for B'203.

(4) Embodiments of the Invention Garnets suitable for magnetic devices are typically of the same class as yttrium-iron garnet, Y, ~0,2; , is ferrimagnetic with a magnetic moment of about 0.175 Tesla (1750 Gauss) at room temperature. Regarding the manufacturing of magnetic bubble devices with a wide operating temperature range,
A component having the general form R3-xBixh, 01□ was provided. In the above formula, R is a combination of two or more of the rare earth elements of the lanthanide series (atomic numbers 57 to 71). Expression 7. Magnetic moment f Fnn ion gold partial pressure example t-BaGa
It can be changed by substituting ions, so that J
) The resulting substance will have the entire structure formally represented by Rs Fg 5-xGaxQ,2. , provided that Xfd is a positive number less than or equal to 5, preferably less than or equal to 2. The substitution of h may also be by Ge ions, SI ions, or both. In this case, for example λ-, the valence balance can be achieved by replacing some of the rare earth ions with suitable divalent or monovalent ions. It is necessary to take For example, the replacement of rare earth ions by divalent Ge ions is R, -X-
yB i xCa YFa,, -v-wSi vGe
A structure made of wQ...? Form. In addition, in the above formula, y
is approximately equal to v+w.

Magnetic bubble devices are typically based on the use of rare earth ion magnetic garnet materials gold, although layers of other garnets such as gadolinium-gallium garnet and gadolinium aluminum garnet can also be formed according to the present invention. In this case it is necessary that the lattice constant of the substrate is at least as large as that of the layer being grown.
This is almost in agreement with the authors. Is the resulting grown layer magnetically anisotropic in the same way that growth or strain induces pruning? It comes to show.

The easy magnetization direction is, for example, the direction perpendicular to the substrate, similar to the bubble layer. A layer with easily oriented gold in a direction parallel to the substrate is deposited to inhibit bubble gold.

An apparatus suitable for magnetic garnet epitaxial heating according to the present invention is shown as a structural diagram in FIG. In particular, FIG. 1 shows a heating element 1 on a ceramic support tube 2 surrounding a ceramic linear tube 3. The crucible 4 is supported by baffles 5 and contains a melt 6 consisting of garnet and fluxing material.
I have entered.

The panfur 7 serves to completely shield radiation so that the surface of the melt 60 is not excessively cooled.

The substrate 8 is attached to a substrate holder 9 which is attached to a rod 10.

The operation of the device consists in first heating the melt to a high temperature in order to homogenize and equilibrate it, and then to a temperature corresponding to supercooling of the garnet material so that the substrate 8 is immersed in the melt or at least on its surface. Lower the 10 rods until you can feel it,
And usually the rod is rotated with 10k gold. 11 is connected to an exhaust pump.

Figure 2 shows 15 mole percent Bi, 0 to 2 o3.
FIG. 3 shows the melting temperature of a flux formed from 2 mole percent Vz05 or MOO3 and the remaining fraction pbo.

Referring to the entire figure, the melting temperature deviates significantly from a straight line, with local minima for each of the three flux components V2O5°WO2 and MOO5.

Figure 3 shows the total magnetic anisotropy induced during growth, 10-'J/
FIG. 2 is a diagram showing the temperature Ki as a function of supercooling in units of 10' erg/crtl and in units of years. Referring to the entire figure, the magnetic anisotropy induced during growth is directly related to the subcooling temperature as well as to the percent amount of V2O in the flux. This fact is beneficial in the present invention when a fluxing agent added to V2O is used to induce a larger overall magnetic anisotropy at the supercooling temperature. to WO
Similar results can be obtained using 3t or MOO,i.

According to the present invention, the desired magnitude of magnetic anisotropy induced during growth is achieved at as low an undercooling as desired to facilitate layer deposition. For example, for a device with a repeating pattern of approximately 8 μm, approximately 3.2 x 10-'Jl
Er! (32,000erg/c!) It has magnetic anisotropy. As can be seen from FIG. 3, the growth is from a flux consisting essentially of lead oxide and bismuth oxide, i;t, and is supercooled to about 80°C. On the other hand, when the flux contains 9 mole percent vanadium oxide, supercooling is reduced to 50°C.

A magnetic bubble device is formed using all of the layers formed according to the present invention by providing the magnetic layer with means for generating, transporting and detecting magnetic nozzles. C) Such a method is the same as the one mentioned above.
It can take a variety of forms, as reviewed in the paper by Kl et al.

A magnetic thin film, i.e., deposited according to the present invention'! 1. The layer can be used not only in magnetic bubble devices, but also in other devices such as especially magneto-optical devices (198
Deeron (J, F, D) filed on April 29, 2015
(see U.S. Patent Application No. 728,669 by Illo Kuchi et al.).

As shown in the following example, a Carnet thin film was deposited by liquid phase epitaxy onto a discoidal plate of Gd, Gaρ, 2 with a diameter of 5 CrrL. Cleaning of the substrate before layer growth is as follows. 50℃ water 100
1 gram per ml Alco
Place in an ultrasonic bath containing noX )' for 20 minutes, then wash gently with warm water. Next, put it in an ultrasonic bath of water at 50°C for 15 minutes, and then wash it gently with sufficient deionized water-C in 3 steps: 5 minutes each.

Cleaning after growth is as follows J). First H
2O6 volume, HNo, 3 volume and CH, C0OH1
Bring the volume of the gold solution to 75°C, then 1) Add the KIO mixture to 75°C, then wash gently with warm water, and repeat the pre-growth cleaning process.

The substrate is rotated at 75 revolutions per minute in vibration mode during epitaxial growth.

Example 1 The melt was 3.58.1 grams of Y2O3, 2, 10 grams of CaO in a platinum crucible.

134 grams of 5i02.15゜31 grams of Gem2
゜168.0 grams Fat'3.222゜O grams MoO2, 2294 grams pbo and 113.0
Prepared by melting down 81□03k of grams. Bi, o, are added last. In other words, add the other ingredients after they are melted and mixed.1. Ru. The melt is heated to about 1000° C. with a resistive heating coil. At this temperature the melt can react for about 16 hours.

The saturation temperature of this melt is determined as the lowest melting temperature at which no epitaxial growth is observed on polished gadolinium gallium garnet' when immersed in a 2f+-interfused oxide. The saturation temperature of the melt, 890° C., was thus determined.

Approximately 5.1 cnL (2.0 inches) in diameter and 5.0 inches thick. IX
A 10-2 cm (20 mil) disc-shaped gadolinium-gallium garnet substrate is used as the deposited substrate. The substrate is cleaned and dried and placed in a substrate holder.

The temperature of the melt is lowered to about 792° C., and the substrate is placed 1 cm below the surface of the melt. The substrate is held in this position for approximately 6 minutes. It is then immersed and rotated to a depth of about 21 degrees of melt width. At this time, the direction of rotation reverses every second. After the substrate has been immersed for about 6 minutes, it is pulled out of the melt to a position 1 cm above the melt 1°.The rotation continues at this point.

Stop the rotation and allow the melt to drip off the substrate. This draining process requires approximately 8';)'4r, followed by high speed rotation to remove the entire droplet of melt on the substrate. The substrate is pulled up at a speed of 13 (shoulder, 6) minutes.

The following physical properties lv1 of the deposited layer were determined by standard measurement techniques. .

The layer thickness is approximately 2.21 μm, the width of the magnetic domain stripes is approximately 1, (i
('+μm, saturation magnetization (usually given by 41 TMS) approximately 7.16 x 10" Tesla (716 Gauss).

Anisotropy field (usually expressed as 1) 0.259 Tesla (2590 Gauss), material length parameter (materi)
the length parameter (usually expressed as t) is about 0.16 μm, the lattice constant (usually expressed as aO) is about 1.240501 m, and - the axial anisotropy (
Approximately 9.52 x 10-J/
ctl (95200erg/aA) (after distortion correction).

The structure of the layer is n determined as shown in the following equation.

(Yl, 74 B'0.66 C"0.60) CFl
4.46 S 10.30 Ge0.30)OH2 Example 2 The procedure is the same as described in Example 1 except for the composition of the melt. The melt contains 8.70 grams of Y2O3 and 1.35 grams of G.
d2O3, 2.35 g HO20, 6.75 g CaO, 27.0 g sio□, 16.0
Gram Gem2.428.0 Gram Fx203.3
64-0 grams of V2O,.

5880 grams pbo and 1312 grams B+2
Consists of 03. Saturation temperature is approximately 890℃, growth temperature is 80℃
5° C., and other characteristic parameters are as follows. Layer thickness 2.00 μm, domain width 1.63 μm, saturation magnetization 6.2 × 10-2 Tesla (620 Gauss), anisotropy field 0
゜17 Tesla (1700 Gauss), material length 0.16 μm
, lattice constant 1.2334 nm, and uniaxial anisotropy 4
．． 19 x 10-3 J/i (41900 erg/state).

The structure of the grown thin film is as shown in the following equation.

(Yl, 43 GdQI4 Hoo, 23 B'q 5
0 C"0.70) (Fe2.so S'0,52
GeO,I II ) 012 Example 3 The procedure is the same as described in Example 1 except for the melt composition.

The composition of the melt is 1.61 grams of Y2O, 1,55
grams of Ca0, 4.50 grams of Gem2.4.2
0g of 5Io2゜85.2g of Fn203,
73.0 grams of WO,.

134.0 grams of B 12o3 and 740.0 grams of Pl)0. The saturation temperature is about 920°C, the growth temperature is about 841°C, and other characteristic parameters are as follows. Layer thickness 1.75 μm, magnetic domain width 1.55 μm,
Collapse field 3.74X10-2 Tesla (374 Gauss), saturation magnetization 6.71 X I Q-2 Tesla (671 Gauss).

Lattice constant 1.2384μm, and -axial anisotropy 5.1
5 X 10' J/crd (51500erg/
crl).

The structure of the grown thin film is expressed by the following equation.

(Yl, 91 BIO, 44CaO, a 5 ) (
Fh, 3s Geo, 23 S 'o, e' 0+
20 Example 4 The melt contained approximately 1.80 grams of Y, 03°1.
30 grams of Ca0, 6.00 grams of sio,
.

2.50 grams Gem2, 84.00 grams Fx2
03°168.00 grams of Cry, , 1550.
00 grams pbo and 295.00 grams B12
o3 Formed by melting in an all-platinum crucible.

B r 203 is added at the end after the other ingredients are melted and mixed together. The melt is heated by a resistive heating coil to a temperature of approximately 1000°C. At this temperature the melt is allowed to react for about 16 hours. The saturation temperature of this melt is determined from 1 to the lowest melting temperature of a polished gadolinium gallium garnet on which no epitaxial growth is observed when immersed in the melt for 22 minutes.

The saturation temperature of the melt in this example, 881° C., was thus determined.

A disc-shaped gadolinium-gallium garnet substrate 2.0 inches in diameter and 5.120 mils thick is used as the fully deposited substrate. The substrate is cleaned and dried and placed in a substrate holder.

The temperature of the melt was lowered by a growth temperature controller of 795°C, and the temperature was lowered to 1 m below the surface of the substrate. The substrate is held in this position for approximately 6 minutes. Then the melt width is about 2crr
It is immersed to a depth of L and rotated at about 100 revolutions per minute.

At this time, the direction of rotation reverses every second. The board is about 6
After soaking for minutes, from the melt, 1 cM above the melt.
It is pulled out at position 1. Note that the rotation continues at this time as well.

The entire rotating body removes the melt from the substrate. This draining process requires about 8 minutes, followed by high speed rotation to remove the droplets of melt on the substrate. The board is 1
It is lifted at a speed of 3c1rL/e.

The following physical properties of the deposited layers were determined using standard measurement techniques.

Layer thickness approximately 1.82 μm, magnetic domain stripe width approximately 1.35 μm
, saturation magnetization (normally captured by 4πMS) approximately 0.085
3 Tesla (853 Gauss).

Anisotropy field (usually expressed as ik) 0.249 Tesla (2490 Gauss), material length parameter approximately 0.13μ
m, lattice constant (usually expressed as aOπ) approximately 1.2385
4 nm, and -axial anisotropy approximately 8.63 x 10-
'J/* (863 (10erg/ci) (after distortion correction).

The structure of the layer was determined as follows.

(Y 1,113 B'0.54 CaO,53) (
FJI4.478! o, 42 ceO, I+ )01
2 Q

[Brief explanation of drawings]

FIG. 1 is a structural diagram of a device used for liquid phase epitaxial growth of magnetic garnet thin films according to the present invention, and FIG.
bo-Bi, , o, added to the flux t' v2o3.
A diagram showing the melting temperature as a function of the amount of wo, or MOO8, FIG. FIG. 4 is a diagram showing the magnetic anisotropy for different amounts of as a function of subcooling temperature; [Explanation of main symbols]

Claims (1)

[Scope of Claims] 1. A magnetic device comprising a layer of garnet material containing bismuth, said layer being epitaxially deposited on the surface of a supporting substrate, comprising a predetermined magnetic device consisting essentially of garnet material and flux material. heating the melt to a temperature corresponding to supercooling of the garnet material, the fluxing material comprising lead oxide and bismuth oxide, and positioning the substrate so that at least its surface is in contact with the melt. and a method for manufacturing a magnetic device comprising separating the substrate from the melt after a layer has been deposited on the surface of the substrate, wherein the fluxing agent comprises at least vanadium oxide, tungsten oxide, molybdenum oxide and further comprising any one of chromium oxides as an additional fluxing oxide component;
Bismuth oxide is present in the fluxing material in an amount ranging from 0 to 98 mole percent as an amount of Bi_2O_3.
to 30 mole percent, said at least one additional oxide component being present in the flux material at V_2
O_3 or WO_3 or MoO_3 or CrO_
3 in an amount ranging from 1 to 20 mole percent, and the temperature of supercooling is selected depending on the amount of said additional fluxing agent oxide component such that a predetermined magnetic anisotropy is achieved in said layer. A method for manufacturing a magnetic device, characterized in that: 2. A method according to claim 1, characterized in that the additional oxide component is included in the fluxing material in an amount ranging from 3 to 15 mole percent of V_2O_3 or WO_3 or MoO_3. Method of manufacturing the device. 3. A method for manufacturing a magnetic device according to claim 1, wherein the additional oxide component is vanadium oxide. 4. The method of manufacturing a magnetic device according to claim 1, wherein the additional oxide component is tungsten oxide. 5. The method of manufacturing a magnetic device according to claim 1, wherein the additional oxide component is molybdenum oxide. 6. The method of manufacturing a magnetic device according to claim 1, wherein the additional oxide component is chromium oxide.