JPH01230498A - Method for forming garnet membrane - 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 Field of Application of Industry-4-J The present invention relates to a method for forming a garnet film by a liquid phase epitaxial method.

"Prior Art" Garnet films are used as Faraday elements for magnetic field sensors and optical isolators, and a liquid phase epitaxial method is known as one means for forming the garnet films.

In the case of such a liquid phase epitaxial method, one side of a rotating single crystal substrate is brought into contact with a garnet melt maintained in a supercooled state below the saturation temperature at which garnet crystals precipitate, and garnet is deposited on the substrate surface. It is common to grow a film.

In the case of the two conventional methods, as shown in FIG. 6, a garnet film is grown on the epitaxial growth surface 2 of a disk-shaped single crystal substrate 1. I try to do that.

When growing a garnet film using such a substrate 1, as the garnet film 3 becomes thicker, various plane orientations are formed at the edge of the film, as shown in FIG.
This prevents the smooth flow of the melt to the film surface, so the film thickness
Uniformity of film composition cannot be obtained.

Moreover, since the single-crystal substrate 3 is circular, the stirring effect on the melt is poor, which is also a cause of inhibiting the uniformity and quality of film formation.

In view of the above-mentioned problems, the present invention aims to provide a method for forming a garnet film that can ensure good quality of film formation, high speed, and agitation of the melt.

"Means for Solving the Problems" In order to achieve the intended purpose, the present invention maintains the crystal growth surface of a rotating single crystal substrate in a supercooled state below the saturation temperature at which garnet crystals precipitate. In the method for forming a garnet film in which a garnet film is grown on the crystal growth surface by bringing the garnet film into contact with the garnet melt, a hexagonal single crystal substrate is prepared, and the substrate is rotated. The crystal growth surface of the garnet is brought into contact with the garnet melt.

1 Effect 1 In the method of the present invention, as described above, while rotating a hexagonal single crystal substrate, the crystal growth surface of the substrate is brought into contact with a garnet melt at a predetermined temperature, and garnet is applied to the crystal growth surface of the substrate. Grow the film.

In the case of the method of the present invention, a garnet film having a uniform thickness and composition is grown at high speed on the crystal growth surface due to the reason described later, namely, the rationality of the hexagonal shape of the single crystal substrate.

``Example J'' Examples of the method of the present invention will be described below with reference to the drawings.

FIG. 1 illustrates an apparatus for carrying out the method of the invention.

In FIG. 1, an electric furnace 11 includes a core tube 12 made of HB ceramic, a heater 13 made of Kanthal alloy wound around the outer periphery of the core tube 12, and a crucible pedestal 14 disposed inside the core tube 12. , a furnace lid 16 having an entrance/exit hole 15 formed on the upper surface of the furnace core tube 12, and a thermocouple 17 made of platinum/rhodium for measuring the furnace temperature.

In the electric furnace 11 described above, an alumina support rod 18 having a platinum holder at the lower end is inserted into the furnace core tube 12 so as to be vertically movable and rotatable, as shown in FIG. A crucible 20 made of platinum is placed on a crucible pedestal 14'' within the furnace core tube 12.

The single crystal substrate 21 held via the holder 18 of the support s19 is made of, for example, a wafer of GGG (Gd3Ga50+2), and the single crystal substrate 21 is
As shown in the figure, the outer shape is a regular hexagon, and one side is the crystal growth surface 22 of the garnet film.

The materials of the garnet film melted in the crucible 18 are PbO, B2O3, Bi2O3, Fe2O3, Gd2O.
:+, Y2O3, Tm2O3, etc. Among these, Bz03. Bi2O3 is a solvent and the others are solutes.

The solvent in this case is used to lower the melting point of the solute.

In FIGS. 1 and 2, these materials are shown in the form of a melt 23 inside the crucible 18.

In the figure, 24 is a garnet film obtained by the method of the present invention.

When implementing the method of the present invention in the illustrated example described above, the following will occur.

The single crystal substrate 21 is held horizontally via the holder 18 of the support rod 19 and then inserted into the furnace tube 12 of the electric furnace 11 .

In the electric furnace 11, a predetermined material (solvent, solute) put into a crucible 18 is heated and melted by a heater 13 to create a melt 23, and the melt 23 is heated to a temperature below the saturation temperature at which garnet crystals precipitate. Maintain in supercooled state.

Thereafter, the support rod 19 is rotated and lowered to bring the crystal growth surface 22 of the single crystal substrate 21 into contact with the garnet melt 23 .

As is known, the natural growth plane of a garnet single crystal is [110
1 plane, [2111 plane, and when a bulk garnet single crystal is grown on the crystal growth plane 22 of the single crystal substrate 21 from the garnet melt 23 made of a mixture of a predetermined solvent and solute, such a single crystal is grown. As shown in Figure 5, the crystal is [
The crystal shape is surrounded by the [110] and [2111] planes.

In such a crystal, the [1111 plane has a hexagonal shape as shown by the dotted line in FIG.

Moreover, the [111] plane of the single crystal substrate 21 has a [111
] Since the garnet film (single crystal) grows on the surface, since the single crystal substrate 21 has a hexagonal shape, there is a natural growth surface on the edge of the single crystal substrate 21 as shown in FIGS. 3 and 4. A garnet film 24 having [110] planes and [211] planes grows uniformly at high speed.

At the same time, the hexagonal shape of the single crystal substrate 21 exerts a stirring action on the garnet melt 23, thereby further improving the quality and speed of film formation.

In a specific example of the method of the invention, the single crystal substrate 21 is
Regular hexagon made of d5Ga50+2 (diameter of circumscribed circle 25 mm
φ), and the garnet melt 23 is PbO, B2O3, B
(BiGd)sFe5 on the crystal growth surface 22 of the single crystal substrate 21 as i2O3, Fe2[)3, Gd2O3
A 400 gm thick garnet film 24 consisting of 0+2 was grown.

At this time, the film formation rate was 0.75 μm/min according to the conventional method.
The variation in film thickness was reduced from 10 gm in the conventional method to 3 pm.

In another embodiment of the method of the invention, the single crystal substrate 21
A regular hexagon made of GdzGasO+z (circle diameter 50
)φ), and the garnet melt 23 is PbO, B2O3,
As Fe2O3, Y20a, and Gd2O3, a film of (GdY)3Fe50+ 2 with a thickness of 150 gm is formed on the crystal growth surface 22 of the single crystal substrate 21. 17) Garnet 1lfi 2
I grew 4.

At this time, the growth rate was 0.32 μm/m in the conventional method.
1. from in to 0.45gm/min. As a result, the variation in film thickness was reduced from 5 gm in the conventional method to 2 gm.

tl' Effect of the invention 1 As explained below, in the method of the present invention, the crystal growth surface of the hexagonal single crystal substrate is brought into contact with the garnet melt while rotating the substrate to form a garnet film. Therefore, a garnet film (single crystal) with good film quality can be formed at high speed using a rationally shaped single crystal substrate that also exhibits stirring properties.

[Brief explanation of the drawing]

FIG. 1 is a sectional view schematically showing an embodiment of the method of the present invention together with the equipment used therein, FIG. 2 is an enlarged view of the main part of the same 1-,
Figures 3 and 4 are a plan view and a front view of a garnet film formed on a single crystal substrate using the method of the present invention, Figure 5 is an explanatory diagram of a bulk garnet single crystal, and Figure 6 is a conventional single crystal substrate. FIG. 7 is a perspective view of a garnet film formed on a conventional single crystal substrate. 11... Electric furnace 12... Furnace tube 13... Heater 18... Holter 19... Support body 20... Crucible 21...Single crystal substrate 22...Crystal growth surface 23...Garnet melt 24...Garnet film Agent Patent attorney Yoshio Saifuji

Claims (1)

[Claims] A garnet method in which a crystal growth surface of a rotating single crystal substrate is brought into contact with a garnet melt maintained in a supercooled state below the saturation temperature at which garnet crystals precipitate, thereby growing a garnet film on the crystal growth surface. In the film forming method, a hexagonal single crystal substrate is prepared,
A method for forming a garnet film, comprising bringing the crystal growth surface of the substrate into contact with the garnet melt while rotating the substrate.