MANUFACTURING METHOD OF NITRIDE SEMICONDUCTOR ULTRAVIOLET LIGHT EMITTING ELEMENT, AND NITRIDE SEMICONDUCTOR ULTRAVIOLET LIGHT EMITTING ELEMENT

• US 20190228972A1
• Filed: 11/08/2017
• Published: 07/25/2019
• Est. Priority Date: 02/15/2017
• Status: Active Grant

• Current Assignee: Nikkiso Company Limited
• Original Assignee: Soko Kagaku Co Ltd
• Inventors: HIRANO, Akira, NAGASAWA, Yosuke, CHICHIBU, Shigefusa, KOJIMA, Kazunobu
• Granted Patent: US 10,643,849 B2
• Time in Patent Office: Days
• CPC Class Codes: H01L 21/0242 Crystalline insulating materials
• CPC Class Codes: H01L 21/02433 Crystal orientation
• CPC Class Codes: H01L 21/02458 Nitrides
• CPC Class Codes: H01L 21/02505 consisting of more than two layers
• CPC Class Codes: H01L 21/0254 Nitrides
• CPC Class Codes: H01L 21/02576 N-type
• CPC Class Codes: H01L 21/0262 Reduction or decomposition of gaseous compounds, e.g. CVD
• CPC Class Codes: H01L 21/02631 Physical deposition at reduced pressure, e.g. MBE, sputtering, evaporation
• CPC Class Codes: H01L 33/007 comprising nitride compounds
• CPC Class Codes: H01L 33/06 within the light emitting region, e.g. quantum confinement structure or tunnel barrier
• CPC Class Codes: H01L 33/32 containing nitrogen
• CPC Class Codes: H01L 33/38 with a particular shape

Abstract

A manufacturing method of a nitride semiconductor ultraviolet light-emitting element having a peak emission wavelength of 285 nm or shorter comprises a first step of forming an n-type semiconductor layer composed of an n-type Al_XGa_1-XN-based semiconductor (1≥X≥0.5) on an upper surface of an underlying portion including a sapphire substrate, a second step of forming, above the n-type semiconductor layer, an active layer that includes a light-emitting layer composed of an Al_YGa_1-YN-based semiconductor (X>Y>0) and that is composed of an AlGaN-based semiconductor as a whole, and a third step of forming a p-type semiconductor layer composed of a p-type Al_ZGa_1-ZN-based semiconductor (1≥Z>Y) above the active layer. In the manufacturing method, a growth temperature at the second step is higher than 1200° C. and equal to or higher than a growth temperature at the first step.

Claims

1. A manufacturing method of a nitride semiconductor ultraviolet light-emitting element having a peak emission wavelength of 285 nm or shorter comprising:

a first step of forming an n-type semiconductor layer composed of an n-type Al_XGa_1-XN-based semiconductor (1≥

0.5) on an upper surface of an underlying portion including a sapphire substrate;

a second step of forming, above the n-type semiconductor layer, an active layer that includes a light-emitting layer composed of an Al_YGa<sub>1−

Y</sub>N-based semiconductor (X>

Y>

0) and that is composed of an AlGaN-based semiconductor as a whole; and

a third step of forming a p-type semiconductor layer composed of a p-type Al_ZGa_1-ZN-based semiconductor (1≥

Z>

Y) above the active layer, wherein

a growth temperature at the second step is higher than 1200°

C. and equal to or higher than a growth temperature at the first step.

2. The manufacturing method of a nitride semiconductor ultraviolet light-emitting element according to claim 1, wherein a growth temperature at the second step is higher than a growth temperature at the first step.

3. The manufacturing method of a nitride semiconductor ultraviolet light-emitting element according to claim 2, further comprising a fourth step of forming a first decomposition prevention layer following the n-type semiconductor layer at a same growth temperature as the first step immediately after the first step, wherein

the n-type semiconductor layer composed of an n-type Al_XGa_1-XN-based semiconductor (1>

X≥

0.5) is formed at the first step,

the first decomposition prevention layer is composed of an Al_α

Ga_1-α

N-based semiconductor (1≥

α

>

X), and has a thickness of 3 nm or less, and

at least after the fourth step ends, a growth temperature is increased and then the second step is performed.

4. The manufacturing method of a nitride semiconductor ultraviolet light-emitting element according to claim 1, wherein a growth temperature at the third step is lower than a growth temperature at the second step.

5. The manufacturing method of a nitride semiconductor ultraviolet light-emitting element according to claim 4, further comprising a fifth step of forming a second decomposition prevention layer following the active layer at a same growth temperature as the second step immediately after the second step, wherein

an uppermost layer of the active layer is composed of an Al_Y1Ga_1-Y1N-based semiconductor (X>

Y1 Y),

the second decomposition prevention layer is composed of an Al_β

Ga_1-β

N-based semiconductor (1≥

β

>

1), and has a thickness of 3 nm or less and

at least after the fifth step ends, a growth temperature is reduced and then the third step is performed.

6. The manufacturing method of a nitride semiconductor ultraviolet light-emitting element according to claim 1, further comprising a sixth step of forming a p-type contact layer composed of a p-type Al_QGa_1-QN-based semiconductor (Z>

Q≥

0) above the p-type semiconductor layer, wherein

a growth temperature at the sixth step is lower than a growth temperature at the third step.

7. The manufacturing method of a nitride semiconductor ultraviolet light-emitting element according to claim 6, further comprising a seventh step of forming a third decomposition prevention layer following the p-type semiconductor layer at a same growth temperature as the third step immediately after the third step, wherein

the p-type semiconductor layer composed of a p-type Al_ZGa_1-ZN-based semiconductor (1>

Z >

Y) is formed at the third step,

the third decomposition prevention layer is composed of an Al_γ

Ga_1-γ

N-based semiconductor (1≥

γ

>

Z), and has a thickness of 3 nm or less, and at least after the seventh step ends, a growth temperature is reduced and then the sixth step is performed.

8. The manufacturing method of a nitride semiconductor ultraviolet light-emitting element according to claim 7, wherein a growth temperature at the sixth step is lower than a growth temperature at the third step by 150°

C. or more.

9. The manufacturing method of a nitride semiconductor ultraviolet light-emitting element according to claim 1, further comprising an eighth step of performing a thermal treatment at a temperature higher than 1200°

C. while supplying a gas containing 50% or more of nitrogen at least after the second step ends.

10. The manufacturing method of a nitride semiconductor ultraviolet light-emitting element according to claim 6, wherein a growth temperature at the third step is equal to or lower than 1100°

C.

11. The manufacturing method of a nitride semiconductor ultraviolet light-emitting element according to claim 1, wherein the second step is a step of forming the active layer that has a single or multiple quantum well structure in which one or more well layers functioning as the light-emitting layer and one or more barrier layers composed of an Al_RGa_1-RN-based semiconductor (1>

R>

Y) are alternately laminated.

12. The manufacturing method of a nitride semiconductor ultraviolet light-emitting element according to claim 1, wherein a growth temperature at the second step is equal to or higher than 1250°

C.

13. A nitride semiconductor ultraviolet light-emitting element having a peak emission wavelength of 285 nm or shorter comprising:

an underlying portion including a sapphire substrate;

an n-type semiconductor layer composed of an n-type Al_XGa_1-XN-based semiconductor (1>

X≥

0.5), the n-type semiconductor layer being formed on an upper surface of the underlying portion;

an active layer that includes a light-emitting layer composed of an Al_YGa_1-YN-based semiconductor (X>

Y>

0) and that is composed of an AlGaN-based semiconductor as a whole, the active layer being formed above the n-type semiconductor layer; and

a p-type semiconductor layer composed of a p-type Al_ZGa_1-ZN-based semiconductor (1≥

Z>

Y), the p-type semiconductor layer being formed above the active layer, wherein

an Al composition ratio on an upper surface of the n-type semiconductor layer is larger than that inside of the n-type semiconductor layer, or a first decomposition prevention layer composed of an Al_α

Ga_1-α

N-based semiconductor (1≥

α

>

X) and having a thickness of 3 nm or less is formed on the upper surface of the n-type semiconductor layer.

14. The nitride semiconductor ultraviolet light-emitting element according to claim 13, wherein

an uppermost layer of the active layer is composed of an Al_Y1Ga_1-Y1N-based semiconductor (X>

Y1≥

Y), and

an Al composition ratio on an upper surface of the uppermost layer is larger than that inside of the uppermost layer, or a second decomposition prevention layer composed of an Al_β

Ga_1-β

N-based semiconductor (1≥

β

>

Y1) and having a thickness of 3 nm or less is formed on an upper surface of the active layer.

15. The nitride semiconductor ultraviolet light-emitting element according to claim 13, further comprising a p-type contact layer formed above the p-type semiconductor layer, wherein

the p-type semiconductor layer is composed of a p-type Al_ZGa_1-ZN-based semiconductor (1>

Z>

Y),

the p-type contact layer is composed of a p-type Al_QGa_1-QN-based semiconductor (Z>

Q≥

0), and

an Al composition ratio on an upper surface of the p-type semiconductor layer is larger than that inside of the p-type semiconductor layer, or a third decomposition prevention layer composed of an Al_γ

Ga_1-γ

N-based semiconductor (1≥

γ

>

Z) and having a thickness of 3 nm or less is formed on the upper surface of the p-type semiconductor layer.

16. The nitride semiconductor ultraviolet light-emitting element according to claim 14, further comprising a p-type contact layer formed above the p-type semiconductor layer, wherein

the p-type semiconductor layer is composed of a p-type Al_ZGa_1-ZN-based semiconductor (1>

Z>

Y),

the p-type contact layer is composed of a p-type Al_QGa_1-QN-based semiconductor (Z>

Q≥

A), and

an Al composition ratio on an upper surface of the p-type semiconductor layer is larger than that inside of the p-type semiconductor layer, or a third decomposition prevention layer composed of an Al_γ

Ga_1-γ

N-based semiconductor (1≥

γ

>

Z) and having a thickness of 3 nm or less is formed on the upper surface of the p-type semiconductor layer.