US 2026/0049417 A1Published application

Gallium nitride substrate

AssigneeMitsubishi Chemical Corporation

InventorsTakafumi ODANI, Akinori MIURA, Yuuki ENATSU, Kenta TATE, Tomoyuki TAKAKURA, Masayuki TASHIRO

Life of this patent

Estimating the term…

Abstract

A gallium nitride substrate has a main surface inclined by 0° to 20° from a (0001) plane and having an area of 15 cm2 or more. The main surface has a dislocation density of 5×106 cm−2 or less, and a number density of local strains in a crossed Nicols image obtained by a sensitive color method for the main surface is 0.5 cm−2 or less.

Claims10

Dependent claims

A gallium nitride substrate comprising:

a main surface inclined by 0° to 200 from a (0001) plane and having an area of 15 cm2 or more,
wherein the main surface has a dislocation density of 5×106 cm−2 or less, and
a number density of local strains in a crossed Nicols image obtained by a sensitive color method for the main surface is 0.5 counts·cm−2 or less.

A gallium nitride substrate comprising any one of the following (A) to (C):

(A) a main surface inclined by 0° to 20° from a (0001) plane and having an area of 15 cm2 or more,
wherein a maximum value of a strain evaluation value in the main surface is 1×10−4 or less, the strain evaluation value being calculated by a photoelasticity measurement for the main surface based on the following formula (1):
[
Math
.
1
]
STRAIN
⁢
EVALUATION
⁢
VALUE
:
❘
"\[LeftBracketingBar]"
S
r
-
S
t
❘
"\[RightBracketingBar]"
=
[
(
S
yy
-
S
xx
)
2
+
(
2
⁢
S
xy
)
2
]
1
2
(
1
)
wherein each term in the formula (1) is represented by the following formulae (2) and (3):
[
Math
.
2
]
❘
"\[LeftBracketingBar]"
S
yy
-
S
xx
❘
"\[RightBracketingBar]"
=
λ
⁢
δ
π
⁢
dn
0
3
⁢
❘
"\[LeftBracketingBar]"
cos
⁢
2
⁢
ϕ
p
1
⁢
1
-
p
1
⁢
2
❘
"\[RightBracketingBar]"
(
2
)
2
⁢
❘
"\[LeftBracketingBar]"
S
xy
❘
"\[RightBracketingBar]"
=
❘
"\[LeftBracketingBar]"
(
S
yy
-
S
xx
)
⁢
tan
⁢
2
⁢
ψ
❘
"\[RightBracketingBar]"
(
3
)
wherein δ and ψ represent a phase difference which is a birefringence amount derived from a strain and a principal axis azimuth angle, respectively, λ represents a light source wavelength of a photoelasticity measurement apparatus, d represents a sample thickness, n0 represents a strain-free refractive index with respect to the light source wavelength, |p11−p12| represents a photoelastic tensor component, and among these, λ, n0, and |p11−p12| satisfy the following conditions:
λ
=
633
⁢
nm
;
⁢
n
0
=
2
.
3
⁢
55
;
and
⁢
❘
"\[LeftBracketingBar]"
p
11
-
p
1
⁢
2
❘
"\[RightBracketingBar]"
=
0.
1
⁢
3
,
(B) a main surface inclined by 0° to 200 from a (0001) plane and having an area of 15 cm2 or more,
wherein an area (S1) in which a strain evaluation value is 6×10−5 or more is 0.10% or less of an area of the entire main surface, the strain evaluation value being calculated by a photoelasticity measurement for the main surface based on the following formula (1):
[
Math
.
3
]
STRAIN
⁢
EVALUATION
⁢
VALUE
:
❘
"\[LeftBracketingBar]"
S
r
-
S
t
❘
"\[RightBracketingBar]"
=
[
(
S
yy
-
S
xx
)
2
+
(
2
⁢
S
xy
)
2
]
1
2
(
1
)
wherein each term in the formula (1) is represented by the following formulae (2) and (3):
[
Math
.
4
]
❘
"\[LeftBracketingBar]"
S
yy
-
S
xx
❘
"\[RightBracketingBar]"
=
λ
⁢
δ
π
⁢
dn
0
3
⁢
❘
"\[LeftBracketingBar]"
cos
⁢
2
⁢
ϕ
p
1
⁢
1
-
p
1
⁢
2
❘
"\[RightBracketingBar]"
(
2
)
2
⁢
❘
"\[LeftBracketingBar]"
S
xy
❘
"\[RightBracketingBar]"
=
❘
"\[LeftBracketingBar]"
(
S
yy
-
S
xx
)
⁢
tan
⁢
2
⁢
ψ
❘
"\[RightBracketingBar]"
(
3
)
wherein δ and ψ represent a phase difference which is a birefringence amount derived from a strain and a principal axis azimuth angle, respectively, λ represents a light source wavelength of a photoelasticity measurement apparatus, d represents a sample thickness, n0 represents a strain-free refractive index with respect to the light source wavelength, |p11−p12| represents a photoelastic tensor component, and among these, λ, n0, and |p11−p12| satisfy the following conditions:
λ
=
633
⁢
nm
;
⁢
n
0
=
2
.
3
⁢
55
;
and
⁢
❘
"\[LeftBracketingBar]"
p
1
⁢
1
-
p
1
⁢
2
❘
"\[RightBracketingBar]"
=
0.13
,
and
(C) a main surface inclined by 0° to 20° from a (0001) plane and having an area of 15 cm2 or more,
wherein a ratio (S1/S2) of an area (S1) in which a strain evaluation value is 6×10−5 or more to an area (S2) in which the strain evaluation value is 5×10−5 or more is 50% or less, the strain evaluation value being calculated by a photoelasticity measurement for the main surface based on the following formula (1):
[
Math
.
5
]
STRAIN
⁢
EVALUATION
⁢
VALUE
:
❘
"\[LeftBracketingBar]"
S
r
-
S
t
❘
"\[RightBracketingBar]"
=
[
(
S
yy
-
S
xx
)
2
+
(
2
⁢
S
xy
)
2
]
1
2
(
1
)
wherein each term in the formula (1) is represented by the following formulae (2) and (3):
[
Math
.
6
]
❘
"\[LeftBracketingBar]"
S
yy
-
S
xx
❘
"\[RightBracketingBar]"
=
λ
⁢
δ
π
⁢
dn
0
3
⁢
❘
"\[LeftBracketingBar]"
cos
⁢
2
⁢
ϕ
p
1
⁢
1
-
p
1
⁢
2
❘
"\[RightBracketingBar]"
(
2
)
2
⁢
❘
"\[LeftBracketingBar]"
S
xy
❘
"\[RightBracketingBar]"
=
❘
"\[LeftBracketingBar]"
(
S
yy
-
S
xx
)
⁢
tan
⁢
2
⁢
ψ
❘
"\[RightBracketingBar]"
(
3
)
wherein δ and ψ represent a phase difference which is a birefringence amount derived from a strain and a principal axis azimuth angle, respectively, λ represents a light source wavelength of a photoelasticity measurement apparatus, d represents a sample thickness, no represents a strain-free refractive index with respect to the light source wavelength, |p11−p12| represents a photoelastic tensor component, and among these, λ, n0, and |p11−p12| satisfy the following conditions:
λ
=
633
⁢
nm
;
⁢
n
0
=
2
.
3
⁢
55
;
and
⁢
❘
"\[LeftBracketingBar]"
p
1
⁢
1
-
p
1
⁢
2
❘
"\[RightBracketingBar]"
=
0.13
.

467 more elements

Dependencies are inferred from the claim text.

Facts

Application: 19/311,234Filed 27 Aug 2025
Priority: JP 2023-03025328 Feb 2023
Published: 19 Feb 2026
Term ends: Not estimatedThe source records don’t support an estimate.

Classification12 codes

C30B 29/406
AIII-nitrides: gallium nitride
C01B 21/0632
Binary compounds of nitrogen with metals, with silicon, or with boron, or with carbon, i.e. nitrides; Compounds of nitrogen with more than one…:…
C30B 25/04
Epitaxial-layer growth: pattern deposit, e.g. by using masks
C30B 25/186
Characterised by the substrate: being specially pre-treated by, e.g. chemical or physical means

Family

Application19/311,234Continuation
US 2026/0049417 A1This patent

From the US filing history. Foreign family members aren’t listed.

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