Reflective mask blank, reflective mask and method of manufacturing semiconductor device
Provided is a reflective mask blank having a phase shift film for which there is little dependency of phase difference on film thickness. The reflective mask blank has a multilayer reflective film and a phase shift film, which causes a shift in the phase of EUV light, formed on a substrate in that order, wherein the phase shift film has an uppermost layer and a lower layer other than the uppermost layer and satisfies the following relationships: n 2 <n 1 <1 and λ/4×(2m+1)−α≤n 1 ·d 1 ≤λ/4×(2m+1)+α. (In the formulas, n 1 represents the refractive index of the uppermost layer at an exposure wavelength of λ=13.5 nm, n 2 represents the refractive index of the lower layer at an exposure wavelength of λ=13.5 nm, d 1 represents the film thickness (nm) of the uppermost layer, m represents an integer of not less than 0, and α=1.5 nm).
1. A reflective mask blank comprising a multilayer reflective film and a phase shift film, which causes a shift in the phase of EUV light, formed on a substrate in that order, wherein
the phase shift film has an uppermost layer and a lower layer other than the uppermost layer and satisfies the following relationships:
n 2 <n 1 <1 (1)
λ/4×(2 m+ 1)−α≤ n 1 ·d 1 ≤λ/4×(2 m+ 1)+α (2)
(wherein, n 1 represents the refractive index of the uppermost layer at an exposure wavelength of λ=13.5 nm, n 2 represents the refractive index of the lower layer at an exposure wavelength of λ=13.5 nm, d 1 represents the film thickness (nm) of the uppermost layer, m represents an integer of not less than 0, and α=1.5 nm).
2. The reflective mask blank according to claim 1 , wherein the value of m is not more than 2.
3. The reflective mask blank according to claim 1 , wherein the uppermost layer of the phase shift film is composed of a material comprising a silicon compound, and the lower layer is composed of a material comprising a tantalum compound.
4. The reflective mask blank according to claim 1 , wherein the reflective mask blank comprises a protective film between the multilayer reflective film and the phase shift film.
5. A reflective mask in which the phase shift film in the reflective mask blank according to claim 1 comprises a patterned phase shift film pattern.
6. A method of manufacturing a semiconductor device comprising forming a pattern on a semiconductor substrate using the reflective mask according to claim 5 .
7. A reflective mask blank comprising a multilayer reflective film and a phase shift film, which causes a shift in the phase of EUV light, formed in that order on a substrate, wherein the phase shift film comprises at least one cycle of a unit thin film, and
wherein each of the at least one cycle of the unit thin film comprises N layers, N being an integer of not less than two, the N layers including at least a first layer and a second layer, the first layer being uppermost among the N layers and located farthest from the multilayer reflective film, and wherein each cycle of the unit thin film satisfies the following relationship:
λ
/
4
×
(
2
m
+
1
)
-
α
≤
∑
i
=
1
N
(
n
i
·
d
i
)
≤
λ
/
4
×
(
2
m
+
1
)
+
α
(
3
)
(wherein, i represents an integer of 1 to N, n i represents the refractive index of the i-th layer at an exposure wavelength of λ=13.5 nm, d i represents the film thickness (nm) of the i-th layer, n i+1 <n i , n 1 <1, and α=1.5 nm).
8. The reflective mask blank according to claim 7 , wherein N=2.
9. The reflective mask blank according to claim 7 , wherein the first layer comprises at least one type of metal material selected from Ta and Cr.
10. The reflective mask blank according to claim 7 , wherein the second layer comprises at least one type of metal material selected from Mo, Ru, Pt, Pd, Ag and Au.
11. The reflective mask blank according to claim 7 , wherein the reflective mask blank comprises a protective film between the multilayer reflective film and the phase shift film.
12. A reflective mask in which the phase shift film in the reflective mask blank according to claim 7 comprises a patterned phase shift film pattern.
13. A method of manufacturing a semiconductor device comprising forming a pattern on a semiconductor substrate using the reflective mask according to claim 12 .