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US 10,241,390 B2Granted
Reflective mask blank and process for producing the reflective mask blank
AssigneeAGC Inc.
InventorHiroshi Hanekawa
Life of this patent
Estimating the term…
Abstract
To provide a reflective mask blank having pseudo defects significantly excluded. The reflective mask blank comprises a substrate, a reflective layer for reflecting EUV light, formed on the substrate, and an absorber layer for absorbing EUV light, formed on the reflective layer, wherein Ssk<1.0 is satisfied, where Ssk is skewness in a region of 1 μm×1 μm on the absorber layer side surface.
Claims17
A reflective mask blank comprising:
- a substrate,
- a reflective layer for reflecting extreme Ultra-Violet (EUV) light, formed on the substrate, and
- an absorber layer for absorbing EUV light, formed on the reflective layer,
- wherein Ssk<1.0 is satisfied, where Ssk is skewness in a region of 1 μm×1 μm on the absorber layer side surface, or Sku<10 is satisfied, where Sku is kurtosis in a region of 1μm×1 μm on the absorber layer side surface,
- wherein the skewness Ssk is represented by the following formula (3):
- S
- sk
- =
- 1
- S
- q
- 3
-
- [
- 1
- A
-
- ∫
- ∫
- A
-
- z
- 3
-
- (
- x
- ,
- y
- )
-
-
- dxdy
- ]
- ,
- Formula
-
-
- (
- 3
- )
- wherein the skewness Ssk represents a symmetry of concaves and convexes to a standard height Sq, wherein Sq is represented by the following formula (2):
- S
- q
- =
- 1
- A
-
- ∫
- ∫
- A
-
- z
- 2
-
- (
- x
- ,
- y
- )
-
-
- dxdy
- ,
- Formula
-
-
- (
- 2
- )
- wherein A represents a standard area of a surface to be evaluated, and
- wherein the kurtosis Sku is represented by the following formula (4):
- S
- ku
- =
- 1
- S
- q
- 4
-
- [
- 1
- A
-
- ∫
- ∫
- A
-
- z
- 4
-
- (
- x
- ,
- y
- )
-
-
- dxdy
- ]
- ,
- Formula
-
-
- (
- 4
- )
- wherein the kurtosis Sku represents a peaked state of convexes or concaves to the standard height Sq.
104 more elements
A process for producing a reflective mask blank, comprising:
- (1) forming a reflective layer for reflecting extreme Ultra-Violet (EUV) light, on a substrate, and
- (2) forming an absorber layer for absorbing EUV light, on the reflective layer, wherein Ssk<1.0 is satisfied, where Ssk is skewness in a region of 1μm×1μm on the surface of the absorber layer obtained in (2), or Sku<10 is satisfied, where Sku is kurtosis in a region of 1 μm×1 μm on the surface of the absorber layer obtained in (2),
- wherein the skewness Ssk is represented by the following formula (3):
- S
- sk
- =
- 1
- S
- q
- 3
-
- [
- 1
- A
-
- ∫
- ∫
- A
-
- z
- 3
-
- (
- x
- ,
- y
- )
-
-
- dxdy
- ]
- ,
- Formula
-
-
- (
- 3
- )
- wherein the skewness Ssk represents a symmetry of concaves and convexes to a standard height Sq,wherein Sq is represented by the following formula (2):
- S
- q
- =
- 1
- A
-
- ∫
- ∫
- A
-
- z
- 2
-
- (
- x
- ,
- y
- )
-
-
- dxdy
- ,
- Formula
-
-
- (
- 2
- )
- wherein A represents a standard area of a surface to be evaluated, and
- wherein the kurtosis Sku is represented by the following formula (4):
- S
- ku
- =
- 1
- S
- q
- 4
-
- [
- 1
- A
-
- ∫
- ∫
- A
-
- z
- 4
-
- (
- x
- ,
- y
- )
-
-
- dxdy
- ]
- ,
- Formula
-
-
- (
- 4
- )
- wherein the kurtosis S ku represents a peaked state of convexes or concaves to the standard height Sq.
102 more elements
A process for producing a reflective mask blank, the process comprising:
- (1) forming a reflective layer for reflecting extreme Ultra-Violet (EUV) light, on a substrate,
- (2) forming an absorber layer for absorbing EUV light, on the reflective layer, and
- (3) forming a low reflective layer against inspection light for inspecting a pattern, having a wavelength of from 190 nm to 260 nm, on the absorber layer, wherein Ssk<1.0 is satisfied, where Ssk is skewness in a region of 1 μm×1 μm on the surface of the low reflective layer obtained in (3), or Sku<10 is satisfied, where Sku is kurtosis in a region of 1μm×1μm on the surface of the low reflective layer obtained in (3),
- wherein the skewness Ssk is represented by the following formula (3):
- S
- sk
- =
- 1
- S
- q
- 3
-
- [
- 1
- A
-
- ∫
- ∫
- A
-
- z
- 3
-
- (
- x
- ,
- y
- )
-
-
- dxdy
- ]
- ,
- Formula
-
-
- (
- 3
- )
- wherein the skewness Ssk represents a symmetry of concaves and convexes to a standard height Sq, wherein Sq is represented by the following formula (2):
- S
- q
- =
- 1
- A
-
- ∫
- ∫
- A
-
- z
- 2
-
- (
- x
- ,
- y
- )
-
-
- dxdy
- ,
- Formula
-
-
- (
- 2
- )
- wherein A represents a standard area of a surface to be evaluated, and
- wherein the kurtosis Sku is represented by the following formula (4):
- S
- ku
- =
- 1
- S
- q
- 4
-
- [
- 1
- A
-
- ∫
- ∫
- A
-
- z
- 4
-
- (
- x
- ,
- y
- )
-
-
- dxdy
- ]
- ,
- Formula
-
-
- (
- 4
- )
- wherein the kurtosis Sku represents a peaked state of convexes or concaves to the standard height Sq.
103 more elements
Dependencies are inferred from the claim text.