APPARATUS FOR MANUFACTURING COMPOUND SINGLE CRYSTAL, METHOD FOR MANUFACTURING COMPOUND SINGLE CRYSTAL, AND GaN SINGLE CRYSTAL

• US 20190330762A1
• Filed: 02/08/2018
• Published: 10/31/2019
• Est. Priority Date: 02/10/2017
• Status: Active Grant

• Current Assignee: Kabushiki Kaisha Toyota Chuo Kenkyusho (Toyota Motor Corporation)
• Original Assignee: Kabushiki Kaisha Toyota Chuo Kenkyusho (Toyota Motor Corporation)
• Inventors: KIMURA, Taishi, NAKAMURA, Daisuke
• Granted Patent: US 11,091,851 B2
• Time in Patent Office: Days
• CPC Class Codes: C30B 23/005 Controlling or regulating flux or flow of depositing species or vapour
• CPC Class Codes: C30B 23/06 Heating of the deposition chamber, the substrate or the materials to be evaporated
• CPC Class Codes: C30B 25/10 Heating of the reaction chamber or the substrate
• CPC Class Codes: C30B 25/14 Feed and outlet means for the gases; Modifying the flow of the reactive gases
• CPC Class Codes: C30B 25/165 the flow of the reactive gases
• CPC Class Codes: C30B 29/38 Nitrides
• CPC Class Codes: C30B 29/406 Gallium nitride
• CPC Class Codes: C30B 35/002 Crucibles or containers

Abstract

An apparatus for manufacturing compound single crystal includes a crystal growth section to hold a seed crystal, a gas supply section to supply a metal-contained gas and a reactant gas toward the seed crystal, and a heating section to heat the seed crystal and a metal source. The gas supply section includes a crucible holding the metal source, a carrier gas supply unit, and a reactant gas supply unit. A porous baffle plate is provided in an opening of the crucible. The porous baffle plate satisfies a relationship of 80%≤(1−V_H/V_B)×100<100% and a relationship of 0.0003<a²/L<1.1. V_B is an apparent volume of the porous baffle plate, V_H is a total volume of the through-holes contained in the porous baffle plate, “a” is a diameter of the through-hole, and L is a length of the through-hole.

Claims

1. A GaN single crystal, having a C impurity amount of less than 8×

10¹⁵ cm<sup>−

3</sup>, an H impurity amount of less than 3×

10¹⁶ cm<sup>−

3</sup>, and an O impurity amount of less than 6×

10¹⁵ cm<sup>−

3</sup>.

2. An apparatus for manufacturing compound single crystal, comprising:

a crystal growth section having a susceptor to hold a seed crystal;

a gas supply section to supply a metal-contained gas (gas containing a metal vapor) generated from a metal source and a reactant gas, the reactant gas reacting with the metal-contained gas to form an inorganic compound, toward the seed crystal; and

a heating section having a heating unit to heat the seed crystal and the metal source,

wherein the gas supply section includes

a crucible disposed separately from the susceptor and holding the metal source,

a carrier gas supply unit that supplies a carrier gas into the crucible, and supplies a mixed gas of the metal-contained gas and the carrier gas toward the seed crystal, and

a reactant gas supply unit to supply the reactant gas toward the seed crystal,

a porous baffle plate is provided in an opening of the crucible, and

the porous baffle plate satisfies Expressions (1) and (2),

80%≤

(1−

V_B/V_B)×

100<

100% 

 

(1)

0.0003<

a²/L<

1.1 

 

(2)

where

V_B is an apparent volume of the porous baffle plate,

V_H is a total volume of through-holes contained in the porous baffle plate,

“

a”

is a diameter of the through-hole, and

L is a length of the through-hole.

3. The apparatus according to claim 2, wherein the through-hole has a portion having a different diameter along a thickness direction of the porous baffle plate.

4. The apparatus according to claim 2, wherein a ratio (S_B/S_L) of area (S_B) of the porous baffle plate to surface area (S_L) of the metal source held in the crucible is 0.1 or more.

5. The apparatus according to claim 2, wherein the crucible is one of a crucible having a relative density of 99% or more and a crucible having an average pore size of 100 μ

m or more.

6. The apparatus according to claim 2, further comprising:

a first movable unit to change one of a vertical distance and a horizontal distance between the porous baffle plate and the susceptor; and

/or

a second movable unit to change one of a vertical distance and a horizontal distance between the heating unit and the crucible.

7. The apparatus according to claim 6,

wherein the susceptor is disposed above the crucible,

the first movable unit is capable of vertically moving the susceptor, and

the second movable unit is capable of vertically moving the heating unit.

8. The apparatus according to claim 2,

wherein the crucible includes

(a) an inner crucible to hold the metal source, and an outer crucible to accommodate the inner crucible,

(b) a carrier gas channel, the carrier gas channel provided between an outer wall surface of the inner crucible and an inner wall surface of the outer crucible so as to flow the carrier gas toward an inside of the inner crucible, and

(c) a carrier gas inlet provided in one of a bottom surface and a side surface of the outer crucible so as to introduce the carrier gas into the carrier gas channel.

9. The apparatus according to claim 8,

wherein the carrier gas channel is capable of flowing the carrier gas toward a top of the inner crucible, and

a carrier-gas flow direction adjuster is provided in an upper part of the outer crucible to change a direction of flow of the carrier gas to a direction toward the metal source after the carrier gas flow has reached the top of the inner crucible.

10. The apparatus according to claim 2,

wherein the reactant gas supply unit has a reactant-gas-flow direction adjuster provided between the susceptor and the crucible, and

the reactant-gas-flow direction adjuster changes a direction of flow of the reactant gas to a direction toward the mixed gas to promote mixing of the mixed gas and the reactant gas.

11. The apparatus according to claim 2, further comprising an angle changing unit that changes a tilt angle of a surface of the seed crystal.

12. The apparatus according to claim 8,

wherein the crucible is a stacked crucible including a first crucible, a second crucible, . . . , and an n-th crucible (n≥

2) stacked upward in this order, the opening of a k-th crucible (1≤

k≤

n−

1) being coupled to the carrier gas inlet of a (k+1)-th crucible, and

the porous baffle plate is provided at least in an opening of the uppermost n-th crucible.

13. A method for manufacturing a compound single crystal, wherein the apparatus for manufacturing compound single crystal according to claim 2 is used to grow a single crystal including the inorganic compound on a surface of the seed crystal under a condition where a temperature of each section satisfies Expression (10),

T_G<

T_D<

T_S<

T_B 

 

(10)

where

T_G is a growth temperature,

T_S is a temperature of the metal source,

T_D is a decomposition temperature of the inorganic compound, and

T_B is a temperature of the porous baffle plate provided in the opening of the crucible.

14. A method for manufacturing a compound single crystal, wherein the apparatus for manufacturing compound single crystal according to claim 12 is used to grow a single crystal including the inorganic compound on a surface of the seed crystal under a condition where a temperature of each section satisfies Expressions (11) and (12),

T_G<

T_D≤

T_Dmax<

T_Sn<

T_B 

 

(11)

T_SK≤

T_SK+1 (1≤

k≤

n−

1) 

 

(12)

where

T_G is a growth temperature,

T_Sn is a temperature of an n-th metal source packed in the n-th crucible,

T_D is a decomposition temperature of the inorganic compound,

T_Dmax is a maximum of the decomposition temperature of the inorganic compound generated from any one of the metal elements contained in the first to n-th metal sources and the reactant gas,

T_Sk is a temperature of a k-th metal source packed in the k-th crucible,

T_Sk+1 is a temperature of a (k+1)-th metal source packed in the (k+1)-th crucible, and

T_B is a temperature of the porous baffle plate provided in the opening of the n-th crucible.

15. The method according to claim 14,

wherein each k-th metal source (1≤

k≤

n) includes only a metal, and

a boiling point of the (k+1)-th metal source is equal to or higher than a boiling point of the k-th metal source.

16. The method according to claim 13 or 14, wherein the carrier gas is supplied such that a flow rate (crucible outlet gas-flow-rate) of the mixed gas passing through the porous baffle plate is 1 m/sec or higher and lower than 20 m/sec.

17. The method according to claim 13 or 14, wherein a single crystal is grown such that growth pressure P satisfies Expression (3), and a distance D between the porous baffle plate and the grown crystal satisfies Expression (4),

0.1 kPa<

P<

6 kPa 

 

(3)

0.5 cm≤

D<

5 cm 

 

(4).

18. The method according to claim 13 or 14,

wherein the metal source includes at least one metal element selected from a group consisting of Al, Ga, In, Zn, Cd, Hg, Si, Ge, Sn, Mg, Mn, Cu, and Ag, and

the reactant gas contains at least any one element selected from a group consisting of C, B, N, P, As, Sb, O, S, Se, and Te.