Ingot, silicon carbide substrate, and method for producing ingot

Patent metadata

Field	Value
Publication number	US-9546437-B2
Application number	US-201414173037-A
Country	US
Kind code	B2
Filing date	Feb 5, 2014
Priority date	Mar 26, 2013
Publication date	Jan 17, 2017
Grant date	Jan 17, 2017

Abstract

An ingot in which generation of crack is sufficiently suppressed is obtained. The ingot includes: a seed substrate formed of silicon carbide; and a silicon carbide layer grown on the seed substrate and containing nitrogen atoms. The silicon carbide layer has a thickness of 15 mm or more in a growth direction. In the silicon carbide layer, a concentration gradient of the nitrogen atoms in the growth direction is 5×10 17 atoms/cm 4 or less.

First claim

What is claimed is:

1. An ingot comprising:
a seed substrate formed of silicon carbide;
a silicon carbide layer grown on said seed substrate and containing nitrogen atoms,
said silicon carbide layer having a thickness of 15 mm or more in a growth direction,
in said silicon carbide layer, a concentration gradient of said nitrogen atoms in said growth direction being 5×10 17 atoms/cm 4 or less;
wherein in said silicon carbide layer, a concentration of nitrogen atoms is 3×10 18 atoms/cm 3 or more and 2×10 19 atoms/cm 3 or less, and
wherein the concentration of nitrogen linearly increases in the growth direction of the ingot.

2. The ingot according to claim 1 , wherein when viewed in said growth direction, the ingot has a width of 100 mm or more.

3. The ingot according to claim 1 , wherein the ingot has a polytype of 4H type.

4. The ingot according to claim 1 , wherein in said silicon carbide layer,
said concentration gradient of said nitrogen atoms in said growth direction is 0.8×10 17 atoms/cm 4 or more.

5. The ingot according to claim 1 , wherein said concentration gradient of said nitrogen atoms is calculated by dividing the value of a difference between the nitrogen atom concentration in a first measurement point and the nitrogen atom concentration in a second measurement point, by a distance between said first measurement point and said second measurement point,
said first measurement point representing a point away from one main surface of said silicon carbide layer by 5 mm in said growth direction, and said second measurement point representing a point away from the other main surface of said silicon carbide layer by 5 mm in said growth direction.

6. A method for producing an ingot, according to claim 1 comprising the steps of:
preparing a seed substrate and a source material each formed of silicon carbide; and
growing a silicon carbide layer containing nitrogen atoms on said seed substrate by sublimating said source material while supplying nitrogen gas and carrier gas,
in the step of growing said silicon carbide layer, at least one of flow rates of said carrier gas and said nitrogen gas being changed to satisfy a Formula (1):

0.6
<

G
⁡

(

t
1

)

⁢

C
⁡

(

t
1

)

/

N
⁡

(

t
1

)

G
⁡

(

t
2

)

⁢

C
⁡

(

t
2

)

/

N
⁡

(

t
2

)

<
2

For
⁢

⁢
mula
⁢

⁢

(
1
)

where G(t1), G(t2) represent growth rates of said silicon carbide layer at times t1, t2 during the growth of said silicon carbide layer, C(t1), C(t2) represent flow rates of said carrier gas at the times t1, t2 during the growth of said silicon carbide layer, N(t1), N(t2) represent flow rates of said nitrogen gas at the times t1, t2 during the growth of said silicon carbide layer.

7. The method for producing the ingot according to claim 6 , wherein the flow rate of said nitrogen gas is changed to satisfy the Formula (1).

Assignees

• Sumitomo Electric Industries

Inventors

• Hori Tsutomu
• Sasaki Makoto
• Kawase Tomohiro

Classifications

• Y10T428/26

  Web or sheet containing structurally defined element or component, the element or component having a specified physical dimension · CPC title

• C30B23/002

  Controlling or regulating · CPC title

• C30B25/16

  Controlling or regulating (controlling or regulating in general G05) · CPC title

• C30B25/14

  Feed and outlet means for the gases; Modifying the flow of the reactive gases · CPC title

• C30B23/005

  Controlling or regulating flux or flow of depositing species or vapour · CPC title