JPH0748441B2 - Method for producing oxide garnet single crystal - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a method for producing an oxide garnet single crystal, and particularly to a uniform method which is useful for applications such as bubble memory, magneto-optical device, and microwave device. The present invention relates to a method for producing an oxide garnet single crystal having a film thickness.

[Prior Art] Generally, an oxide garnet single crystal is manufactured by a liquid phase epitaxial method (hereinafter abbreviated as LPE method), which is used as a garnet component together with a flux such as PbO and B ₂ O _{3 in a} crucible. It is made by melting a metal oxide to form a saturated melt, and then immersing the substrate in this melt and rotating and / or reversing it to grow an oxide garnet single crystal on the substrate. There is.

[Problems to be Solved by the Invention] However, when this oxide garnet single crystal is used as a magnetic bubble, a magneto-optical element, or a microwave element, it is required that various changes in magnetic characteristics are small. . Also, regarding the film thickness that is the basis of the magnetic characteristics, it is required that the film thickness fluctuation within the same wafer is small, but the oxide garnet single crystal produced by this LPE method is used within the same wafer. Since it is difficult to obtain a uniform thickness and the magnetic properties are also non-uniform, the use of this in a magnetic bubble memory results in a large difference in the collapse magnetic field, and when used in a magneto-optical element, the Faraday rotation angle. Of the magnetic resonance half-width (ΔH) when used in a microwave device.
However, there is a disadvantage that sufficient characteristics cannot be obtained due to the large variation on both sides of the wafer, and therefore it cannot be used for these applications.

[Means for Solving the Problems] The present invention relates to a method for producing an oxide garnet single crystal capable of solving such disadvantages, which involves rotating and / or inverting a substrate immersed in a melt. While producing, in the method for producing an oxide garnet single crystal by the liquid phase epitaxial method of growing an oxide garnet single crystal on this substrate, the rotation axis of the substrate is eccentric from the central axis of the melt tank by 5 mm or more, Is what
This is also characterized in that in this liquid phase epitaxial method, the rotation axis of the substrate and the central axis of the melt bath are crossed.

That is, the present inventors have variously studied the method of making the film thickness of the oxide garnet single crystal obtained by the LPE method uniform, the rotational axis of the substrate in the LPE method from the central axis of the melt tank 5mm or more, preferably Is eccentric by 12 mm or more,
The oxide garnet single crystal magnetic film obtained when the rotation axis of the substrate intersects with the center axis of the melt tank has a uniform film thickness because the variation in film thickness within the same film is within ± 3%. The present invention has been completed by discovering that the oxide garnet single crystal can be obtained, and therefore, according to this, it is possible to obtain an oxide garnet single crystal with less variation in magnetic properties.

This will be described in more detail below.

[Operation] Although the oxide garnet single crystal according to the present invention is produced by the LPE method, the garnet substrate single crystal used for growing the target oxide garnet single crystal may be a known one, and Gadolinium gallium
Garnet (hereinafter abbreviated as GGG), samarium gallium garnet (hereinafter abbreviated as SGG), neodymium
Gallium garnet (hereinafter abbreviated as NGG), GGG-based SOG, NOG, YO in which Ca, Mg, Zr or Y is substituted for the above GGG
G [all are trade names of Shin-Etsu Chemical Co., Ltd.], and these are Gd ₂ O ₃ , Sm ₂ O ₃ , Nd ₂ O ₃ or, if necessary, CaO, W.
Substituting elements such as gO, ZrO ₂ and Y ₂ O ₃ together with a predetermined amount of Ga ₂ O ₃ were charged into a crucible and heated to a temperature higher than the melting point of each by high frequency induction to melt, and then the Czochralski method was used from this melt. Can be obtained by pulling a single crystal with.

Further, a known oxide garnet single crystal film, which is epitaxially grown on the substrate single crystal by the liquid phase epitaxial method, may have a composition formula of, for example, Y ₃ Fe ₅ O _3.
12 or (YMFe) ₈ O ₁₂ , where M is La, Bi, Gd, Lu, S
Although at least one element selected from m, Ca, Ge, Ga, Al, Sc, and In is selected, the single crystal represented by the formula Y ₃ Fe ₅ O ₁₂ or (YMFe) ₈ O ₁₂ is platinum. Charge the required amount of metal oxide of each component into the crucible together with the flux components PbO and B ₂ O ₃ , and add 900
A melt may be prepared by heating the mixture to 1,200 ° C to melt it.

The oxide garnet single crystal according to the present invention is produced by immersing the above-mentioned garnet substrate in the melt thus prepared, and pulling it while rotating and / or inverting the oxide garnet single crystal. In producing an oxide garnet single crystal by growing, the rotational axis of this substrate is 5 mm or more from the center axis of the melt tank, preferably 12 mm or more eccentric or crossed, but this eccentric amount is 5 mm.
If it is less than 2 °, the effect is low, and if it is more than 6 °, it is difficult to design the crucible holding structure. However, the crossing angle θ needs to be 2 ° ≦ θ ≦ 6 ° because the effect becomes thin.

FIG. 1 is a vertical sectional view of an oxide garnet single crystal production apparatus by the LPE method according to the present invention, which corresponds to an oxide garnet single crystal in a crucible 1 made of platinum, for example. A melt 2 in which a predetermined amount of metal oxide is melted together with flux components such as PbO and B ₂ O ₃ is housed, and the melt 2 is installed in a vertical growth furnace 4 equipped with a heater 3. To grow an oxide garnet single crystal by the LPE method, a garnet substrate 7 is attached to a pulling machine having a holder 6 on a rod-shaped grip portion 5, the garnet substrate 7 is immersed in the melt 2, and then pulled while rotating and / or inverting. The oxide garnet single crystal is grown on the lever substrate. In the method of the present invention, the rotation axis A of the substrate and the center axis B of the melt tank are 5 mm or more, preferably 12 mm, as shown in the drawing. It is necessary to be eccentric as described above, and if the eccentricity is set to 5 mm or more, the oxide garnet single crystal grown on the substrate 7 has a uniform thickness within ± 3%. Becomes It is to be noted that although the rotation axis A of the substrate and the center axis of the melt tank are not shown in the drawing, this is not the case if, for example, a crucible holding table (not shown) is tilted by 2 ° to 6 °. Good.

[Examples] Next, examples of the present invention will be described.

Example 1 Y ₂ O ₃ 15.8 g and Sm ₂ O ₃ 12.8 which are components of an epitaxial film
g, Lu ₂ O ₃ 29.1 g, CaCO ₃ 29.2 g, Fe ₂ O ₃ 862 g, Ge ₂ O ₂ 161 g and PbO 9,312 g and B ₂ O ₃ 124 g as flux components were weighed and placed in a platinum crucible. And was heated to 1,100 ° C in a vertical annular furnace to melt it.

Then, keep the temperature of this melt at a constant temperature above the supersaturation temperature, insert a 3-inch φ GGG wafer into this GGG.
While pulling the substrate while rotating it to 60 rpm, (YS
mLuCa) ₃ (FeGe) ₅ O ₁₂ oxide garnet single crystal was grown in a film shape, and the thickness and the collapse magnetic field of the epitaxial wafer thus obtained were measured at the 5 points of ~ shown in Fig. 2. As a measurement point, this experiment was carried out by changing the relative position between the substrate rotation axis and the melt tank center axis. The eccentricity (deviation) between the substrate rotation axis and the melt tank center axis
In response to the Was confirmed to change as shown in FIG. 3, and the collapse magnetic field difference (Oe) was changed as shown in FIG.

Example 2 The operation was performed in the same manner as in Example 1, but the crucible holding base in Example 1 was tilted at 0 °, 2 °, 4 °, and 6 ° so that the rotation axis of the GGG substrate and the central axis of the melt bath were set to this. It was confirmed that the collapsible magnetic field difference (Oe) of the obtained epitaxial wafer was changed as shown in FIG. 5 according to the change of the tilt angle of the trough support when the tilt angle was changed.

[Effects of the Invention] As described above, the oxide garnet single crystal according to the present invention is manufactured by using the known liquid phase epitaxial method, in which the axis of rotation of the substrate on which the oxide garnet single crystal is grown and the central axis of the melt tank are 5 mm. The eccentricity or crossing is performed as described above. According to this method, the oxide garnet single crystal obtained has a uniform film thickness within ± 3%, and there is little variation in magnetic properties. It offers the advantage of being able to be used as bubble memory, magneto-optical element, microwave element.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of an oxide garnet single crystal production apparatus used for carrying out the present invention, and FIG. 2 shows the measurement points of the film thickness and the collapse magnetic field of the oxide garnet single crystal wafer obtained in the example. FIG. 3 is a plan view showing the relationship between the eccentricity (deviation) between the substrate rotation axis and the melt bath central axis and the film thickness difference in Example 1, and FIG. 4 shows the eccentricity (deviation) and the collapse magnetic field difference. 5 is a relationship graph between the inclination angle of the crucible holding base and the collapse magnetic field difference in the second embodiment.

Claims (3)

[Claims] 1. A method for producing an oxide garnet single crystal by a liquid phase epitaxial method in which a substrate immersed in a melt is pulled while rotating and / or inverting to grow an oxide garnet single crystal on the substrate. A method for producing an oxide garnet single crystal, characterized in that the rotation axis of is eccentric with respect to the central axis of the melt tank by 5 mm or more. 2. A method for producing an oxide garnet single crystal by a liquid crystal epitaxial method, wherein a substrate immersed in a melt is pulled while rotating and / or inverting, and an oxide garnet single crystal is grown on the substrate. A method for producing an oxide garnet single crystal, characterized by intersecting a rotation axis and a central axis of a melt tank. 3. The method for producing an oxide garnet single crystal according to claim 2, wherein the intersecting angle θ is 2 ° ≦ θ ≦ 6 °.