JP5891028B2 - Method for producing Ga2O3-based substrate - Google Patents

Description

The present invention relates to a method of manufacturing a _Ga 2 _{O 3} system board.

Conventionally, a crystal growth method for simultaneously growing a sapphire single crystal by an EFG method is known (see, for example, Patent Document 1). According to the method described in Patent Document 1, a plurality of sapphire single crystals can be obtained simultaneously by growing crystals from a plurality of slits provided in a die.

A molybdenum crucible or die is used to grow a single crystal of sapphire by the EFG method. Usually, when manufacturing the board | substrate for LED, since the thickness of die | dye becomes 1 mm or less, the thickness of the sapphire single crystal after growth also becomes 1 mm or less like the die thickness. Thereafter, the sapphire single crystal is processed as an LED substrate, the final thickness is about 0.4 mm, and the raw material efficiency is about 40%.

JP 2010-52993 A

An expensive Ir crucible or die is used for the growth of the Ga ₂ O ₃ single crystal by the EFG method. Since the melting point of Ga ₂ O ₃ is as high as about 1700 to 1800 ° C. and does not react with Ga ₂ O ₃ , an Ir crucible or die is used. The present inventors diligently examined whether molybdenum or tungsten, which is another metal material cheaper than Ir, can be used, and both of them resulted in a reaction with Ga ₂ O ₃ .

When manufacturing a die using Ir, with the current manufacturing technology, warpage occurs when the thickness of the Ir plate material is less than 1 mm, and thus the die cannot be manufactured with high accuracy. Therefore, the thickness with which the die can be manufactured with high accuracy is 2.4 mm or more (slit width is 0.4 mm or more). The thickness of the Ga ₂ O ₃ -based single crystal grown using such a die is 2.4 mm, similar to the die thickness. For example, when manufacturing an LED substrate or an electronic device substrate, the thickness must be about 0.4 mm. Therefore, the removal amount of subsequent grinding and polishing is large, and the raw material efficiency is as high as 16.7%. bad.

Accordingly, an object of the present invention is to provide a method for producing a Ga ₂ O ₃ system board which is excellent in raw material efficiency during machining.

One embodiment of the present invention provides a method for producing a Ga ₂ O ₃ -based substrate of [1] to [6 ] in order to achieve the above object.

[1] A step of bringing a seed crystal into contact with a Ga ₂ O ₃ melt overflowing from a slit of the die, and a step of pulling up the seed crystal to grow a plate-like Ga ₂ O ₃ single crystal, The die has a shape in which a cross section perpendicular to the longitudinal direction of the slit has a V-shaped depression at the top, and a V-shaped opening angle of the depression is 150 ° or more and less than 180 °, Ga ₂ O include growth method ₃ system single crystal, the _Ga 2 _{O 3} system were grown the _Ga 2 _{O 3} single crystal by a growth method of a single crystal was cut in a plane direction thereof, a plurality of _Ga 2 _{O 3} system single A method for producing a Ga ₂ O ₃ -based substrate , comprising: a step of forming a crystal plate; and a step of polishing each of the plurality of Ga ₂ O ₃ -based single crystal plates .

[2] The method for manufacturing a Ga ₂ O ₃ -based substrate according to [1], wherein the slit is a plurality of slits.

[3] The method for producing a Ga ₂ O ₃ -based substrate according to [2], wherein the slits are 2 to 5 slits.

[4] The method for producing a Ga ₂ O ₃ -based substrate according to any one of [1] to [3], wherein the thickness of the Ga ₂ O ₃ -based single crystal is 5 mm or more.

[5] The method for producing a Ga ₂ O ₃ -based substrate according to any one of [1] to [4], wherein an interval between the plurality of slits is 3 mm or less.

[6] The _Ga 2 _{O 3} single crystal is cut using a multi-wire saw, the _{[1] ~ [5] Ga} 2 O 3 system method for manufacturing a substrate according to.

According to the present invention, it is possible to provide a manufacturing method of the Ga ₂ O ₃ system board which is excellent in raw material efficiency during machining.

FIG. 1 is a vertical sectional view of a part of an EFG crystal manufacturing apparatus according to an embodiment. FIG. 2 is a partially enlarged view of the die according to the embodiment. FIG. 3 is a perspective view showing a state during growth of a Ga ₂ O ₃ based single crystal. FIG. 4 is a graph showing the relationship between the height of the die where the Ga ₂ O ₃ -based melt rises and the slit width.

Embodiment
In the present embodiment, a Ga ₂ O ₃ single crystal is grown by an EFG (Edge-defined film-fed growth) method.

[Configuration of EFG crystal production equipment]
FIG. 1 is a vertical sectional view of a part of the EFG crystal manufacturing apparatus according to the present embodiment. The EFG crystal manufacturing apparatus 10 excludes a crucible 13 that receives a Ga ₂ O ₃ -based melt 12, a die 14 having a slit 11 (11 a to 11 c) installed in the crucible 13, and an opening of the slit 11. A lid 15 that closes the upper surface of the crucible 13, a seed crystal holder 21 that holds a Ga ₂ O ₃ -based seed crystal (hereinafter referred to as “seed crystal”) 20, and a shaft that supports the seed crystal holder 21 so as to be movable up and down. 22.

The crucible 13 contains a Ga ₂ O ₃ melt 12 obtained by dissolving Ga ₂ O ₃ powder. The crucible 13 is made of a metal material such as iridium having heat resistance that can accommodate the Ga ₂ O ₃ melt 12.

The lid 15 prevents the high-temperature Ga ₂ O ₃ -based melt 12 from evaporating from the crucible 13, and further prevents the vapor of the Ga ₂ O ₃ -based melt 12 from adhering to a portion other than the upper surface of the die 14. .

FIG. 2 is a partially enlarged view of the die according to the present embodiment. The die 14 has a slit 11 for raising the Ga ₂ O ₃ -based melt 12 by capillary action. The slit 11 is composed of a single slit or a plurality of slits, for example, 2 to 5 slits, and can form a thick Ga ₂ O ₃ single crystal 25 as compared with a case of being composed of one slit. it can. In the example shown in FIG. 2, the slit 11 is composed of three slits 11a, 11b, and 11c.

As shown in FIG. 2, the die 14 has a shape in which a cross section perpendicular to the longitudinal direction of the slit 11 has a V-shaped depression at the top. The V-shaped opening angle θ of this depression is 150 ° or more and less than 180 °. In this case, the Ga ₂ O ₃ melt that overflows from the plurality of slits 11a to 11c of the slit 11 easily spreads on the upper surface of the die 14, and forms a single thick Ga ₂ O ₃ single crystal 25 as will be described later. be able to.

The width of each of the slits 11a to 11c constituting the slit 11 can be appropriately selected depending on a desired die height. FIG. 4 is a graph showing the relationship between the height of the die where the Ga ₂ O ₃ -based melt rises and the slit width. Here, ○ in the figure indicates that the Ga ₂ O ₃ melt has risen, and ◆ indicates that the Ga ₂ O ₃ melt has not risen. According to this, for example, when it is desired to set the die height to 50 mm, the slit width may be 0.4 mm or less. Further, in order for the Ga ₂ O ₃ -based melt overflowing from the plurality of slits 11 a to 11 c of the slit 11 to be easily integrated on the upper surface of the die 14, the interval between the slits 11 a to 11 c constituting the slit 11 (slit The distance between 11a and 11b and the distance between slits 11b and 11c) is preferably 3 mm or less.

[Growth Method of Ga ₂ O ₃ System Single Crystal]
The seed crystal 20 is lowered and brought into contact with the Ga ₂ O ₃ -based melt 12 overflowing from the slit 11 by capillary action, and the seed crystal 20 in contact with the Ga ₂ O ₃ -based melt 12 is pulled up to pull up the tabular Ga. _{A 2} O ₃ single crystal 25 is grown.

The Ga ₂ O ₃ -based melt overflowing from the plurality of slits 11a to 11c of the slit 11 spreads as a unit on the upper surface of the die 14, and thereby a single sheet of Ga ₂ having a thickness of, for example, 11 mm or more. O ₃ single crystal 25 grows.

The width of the bottom surface of the seed crystal 20 is smaller than the width of the die 14 in the longitudinal direction, and the Ga ₂ O ₃ single crystal 25 grows while expanding in the longitudinal direction of the die 14 as the seed crystal 20 is pulled up (shoulder expansion). Process). Crystal orientation of the Ga ₂ O ₃ single crystal 25 is equal to the crystal orientation of the seed crystal 20, in order to control the crystal orientation of the _Ga 2 _{O 3} single crystal 25 is, for example, the seed crystal 20 bottom surface orientation and the Adjust the angle in the horizontal plane.

The Ga ₂ O ₃ based single crystal 25 and the seed crystal 20 are Ga ₂ O ₃ single crystal or Ga ₂ O to which elements such as Cu, Ag, Zn, Cd, Al, In, Si, Ge, and Sn are added. ₃ single crystals.

FIG. 3 is a perspective view showing a state during growth of a Ga ₂ O ₃ based single crystal. A surface 26 in FIG. 3 is a main surface of the Ga ₂ O ₃ single crystal 25 parallel to the slit direction of the slit 11. If cut out _Ga 2 _{O 3} single crystal 25 is grown to form a _Ga 2 _{O 3} system board, the plane orientation of the desired major surface of the _Ga 2 _{O 3} based substrate of _Ga 2 _{O 3} single crystal 25 The plane orientations of the planes 26 are matched. For example, when a Ga ₂ O ₃ -based substrate having the (101) plane as the main surface is formed, the plane orientation of the plane 26 is set to (101). The grown Ga ₂ O ₃ single crystal 25 can be used as a seed crystal for growing a new Ga ₂ O ₃ single crystal.

[Method for producing Ga ₂ O ₃ -based substrate]
First, the Ga ₂ O ₃ single crystal 25 is cut in the plane direction (direction parallel to the surface 26) to form a plurality of plate-like Ga ₂ O ₃ single crystal plates. The Ga ₂ O ₃ based single crystal 25 is cut using, for example, a multi-wire saw.

Thereafter, each of the plurality of Ga ₂ O ₃ based single crystal plates is polished to obtain a plurality of Ga ₂ O ₃ based substrates.

For example, when the thickness of the Ga ₂ O ₃ based single crystal 25 is 11 mm, a maximum of 12 Ga ₂ O ₃ based substrates having a thickness of 0.4 mm can be obtained. In this case, the raw material efficiency is about 44%. Note that when a 2.4 mm thick Ga ₂ O ₃ single crystal is formed by a conventional method to obtain a 0.4 mm thick Ga ₂ O ₃ based substrate, the raw material efficiency is 16.7%. It becomes. For this reason, the raw material efficiency of the method of the present embodiment is about 2.6 times the raw material efficiency of this conventional method.

(Effect of embodiment)
According to the present embodiment, a single thick Ga ₂ O film is grown at a speed (for example, 10 to 20 mm / h) equivalent to the speed of growing a single thin (for example, 2.4 mm thick) Ga ₂ O ₃ single crystal. _{A three-} system single crystal can be obtained. Therefore, by polishing the respective cutting the Ga ₂ O ₃ single crystal can be produced efficiently a plurality of Ga ₂ O ₃ based substrate.

The method of the present embodiment includes, for example, a method of growing a Ga ₂ O ₃ -based crystal from a plurality of slits provided in a die and polishing each to form a plurality of Ga ₂ O ₃ -based substrates. Compared with raw material efficiency.

  The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the invention.

  While the embodiments of the present invention have been described above, the embodiments described above do not limit the invention according to the claims. In addition, it should be noted that not all the combinations of features described in the embodiments are essential to the means for solving the problems of the invention.

10 ... EFG crystal manufacturing apparatus, 20 ... seed crystal, 25 ... _Ga 2 _{O 3} single crystal, 11 (11a, 11b, 11c ) ... slit, 14 ... die

Claims (6)

Contacting the seed crystal with a Ga ₂ O ₃ melt overflowing from the slit of the die;
Pulling up the seed crystal and growing a plate-like Ga ₂ O ₃ single crystal;
Including
The die has a shape in which a cross section perpendicular to the longitudinal direction of the slit has a V-shaped depression at the top,
The V-shaped opening angle of the depression is 150 ° or more and less than 180 °.
A method of growing a Ga ₂ O ₃ based single crystal ,
Cutting the grown by a growth method of the Ga ₂ O ₃ single crystal the Ga ₂ O ₃ system single crystal in a plane direction thereof, forming a plurality of Ga ₂ O ₃ single crystal plate,
Polishing each of the plurality of Ga ₂ O ₃ based single crystal plates;
_Ga 2 _{O 3} system method of manufacturing a substrate comprising a. The slit is a plurality of slits,
_Ga 2 _{O 3} system method for manufacturing a substrate according to claim 1. The slits are 2 to 5 slits,
_Ga 2 _{O 3} system method for manufacturing a substrate according to claim 2. The Ga ₂ O ₃ single crystal has a thickness of 5 mm or more.
_Ga 2 _{O 3} system method for manufacturing a substrate according to any one of claims 1 to 3. The interval between the plurality of slits is 3 mm or less.
_Ga 2 _{O 3} system method for manufacturing a substrate according to any one of claims 1 to 4. The Ga ₂ O ₃ single crystal is cut using a multi-wire saw,
_Ga 2 _{O 3} system method for manufacturing a substrate according to claims 1-5.

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