Glass substrate for mask blank, mask blank, photomask, and method for manufacturing glass substrate for mask blank
View Patent ↗A glass substrate for a mask blank includes a rectangular-shaped main surface on which a film having a circuit pattern is to be formed. The main surface includes a quadrangular peripheral frame and a square-shaped center area defined by excluding the frame. The center area has a longitudinal length of 142 mm and a lateral length of 142 mm. A surface morphology of the center area is expressed by the following formulas. A flatness of a sum of compositing all of a kl P k (x)P l (y) is less than or equal to 20 nm when a sum of k and l is greater than or equal to 3 and less than or equal to 9. The flatness is less than or equal to 20 nm when a sum of k and l is greater than or equal to 10 and less than or equal to 30. { z ( x , y ) = ∑ k = 0 N 1 ∑ l = 0 N 2 a kl P k ( x ) P l ( y ) P k ( x ) = 1 2 k k ! d k dx k [ ( x 2 - 1 ) k ] P l ( y ) = 1 2 i l ! d l dy l [ ( y 2 - 1 ) l ]
1. A glass substrate for a mask blank, the glass substrate comprising:
a rectangular-shaped main surface on which a film having a circuit pattern is to be formed;
wherein the rectangular-shaped main surface comprises a quadrangular peripheral frame and a square-shaped center area defined by excluding the quadrangular peripheral frame from the rectangular-shaped main surface,
wherein the square-shaped center area has a longitudinal length of 142 mm and a lateral length of 142 mm, and
wherein a surface morphology of the square-shaped center area z(x, y) is expressed by
{
z
(
x
,
y
)
=
∑
k
=
0
N
1
∑
l
=
0
N
2
a
kl
P
k
(
x
)
P
l
(
y
)
P
k
(
x
)
=
1
2
k
k
!
d
k
dx
k
[
(
x
2
-
1
)
k
]
P
l
(
y
)
=
1
2
i
l
!
d
l
dy
l
[
(
y
2
-
1
)
l
]
wherein x indicates a coordinate in a lateral direction of the mask blank, y indicates a coordinate in a longitudinal direction of the mask blank, and z indicates a coordinates in a height direction of the mask blank, and
wherein a flatness of a sum of combinations of a kl P k (x)P l (y), where k and l are each an integer and a sum of k and l is from 3 to 30, is 22 nm or less.
2. A mask blank comprising:
the glass substrate of claim 1 ; and
a film on which the circuit pattern is to be formed.
3. The mask blank as claimed in claim 2 , wherein the film is a light-shielding film that shields light.
4. The mask blank as claimed in claim 2 ,
wherein the film is an absorbing film that absorbs light, and
wherein a reflection film that reflects the light is provided between the absorbing film and the glass substrate.
5. A photomask comprising:
the glass substrate of claim 1 ; and
a film having the circuit pattern.
6. The photomask as claimed in claim 5 , wherein the film is a light-shielding film that shields light.
7. The photomask as claimed in claim 5 ,
wherein the film is an absorbing film that absorbs light, and
wherein a reflection film that reflects the light is provided between the absorbing film and the glass substrate.
8. A mask blank comprising:
a glass substrate including a rectangular-shaped main surface; and
a film formed on the rectangular-shaped main surface of the glass substrate, a circuit pattern being to be formed on the film;
wherein the main surface of the film on the opposite side of the glass substrate is rectangular-shaped and comprises a quadrangular peripheral frame and a square-shaped center area defined by excluding the quadrangular peripheral frame from the rectangular-shaped main surface,
wherein the square-shaped center area has a longitudinal length of 142 mm and a lateral length of 142 mm, and
wherein a surface morphology of the square-shaped center area z(x, y) is expressed by
{
z
(
x
,
y
)
=
∑
k
=
0
N
1
∑
l
=
0
N
2
a
kl
P
k
(
x
)
P
l
(
y
)
P
k
(
x
)
=
1
2
k
k
!
d
k
dx
k
[
(
x
2
-
1
)
k
]
P
l
(
y
)
=
1
2
i
l
!
d
l
dy
l
[
(
y
2
-
1
)
l
]
wherein x indicates a coordinate in a lateral direction of the mask blank, y indicates a coordinate in a longitudinal direction of the mask blank, and z indicates a coordinates in a height direction of the mask blank, and
wherein a flatness of a sum of combinations of a kl P k (x)P l (y), where k and l are each an integer and a sum of k and l is from 3 to 30, is 22 nm or less.
9. The mask blank as claimed in claim 8 , wherein the film is a light-shielding film that shields light.
10. The mask blank as claimed in claim 8 ,
wherein the film is an absorbing film that absorbs light, and
wherein a reflection film that reflects the light is provided between the absorbing film and the glass substrate.
11. The mask blank as claimed in claim 8 ,
wherein the film is a low reflection film,
wherein the mask blank further comprises:
a reflection film that reflects light, provided between the glass substrate and the low reflection film; and
an absorbing film that absorbs the light, provided between the reflection film and the low reflection film, and
wherein the low reflection film reflects an inspection light of the circuit pattern to be formed on the absorbing film, with reflectivity lower than reflectivity of the absorbing film.