PHOTOMASK BLANK, PHOTOMASK, AND METHOD FOR MANUFACTURING PHOTOMASK
Provided are a photomask blank capable of forming a nanofabrication resist pattern on a resist film with a high accuracy, a method for manufacturing a photomask, and a photomask manufactured by the method. A mask blank ( 100 ) according to the present embodiment is a mask blank used to manufacture a phase shift mask ( 200 ), to which exposure light having a wavelength of 200 nm or less is applied, and includes, in the following order, a translucent substrate ( 1 ), a phase shift film ( 2 ), and a light shielding film ( 3 ), and a hard mask film ( 4 ), in which the light shielding film ( 3 ) is formed of a material containing Cr, the hard mask film ( 4 ) includes a lower layer ( 41 ) positioned on a side of the light shielding film ( 3 ), and an upper layer ( 42 ) configuring an outermost layer of the hard mask film ( 4 ), the lower layer ( 41 ) contains at least one selected from Ta, Te, Ru, and a compound thereof, the upper layer ( 42 ) contains Ta or a Ta compound, and the compound contains at least one selected from O, N, and C.
1 . A photomask blank used to manufacture a photomask to which exposure light having a wavelength of 200 nm or less is applied, the photomask blank comprising, in the following order:
a transparent substrate;
a thin film; and
a hard mask film,
wherein the thin film is formed of a material containing chromium,
the hard mask film includes a lower layer positioned on a side of the thin film, and an upper layer configuring an outermost layer of the hard mask film,
the lower layer contains at least one selected from tungsten, tellurium, ruthenium, and a compound of tungsten, tellurium, or ruthenium,
the upper layer contains tantalum or a tantalum compound, and
the compound contains at least one selected from oxygen, nitrogen, and carbon.
2 . The photomask blank according to claim 1 , wherein a thickness of the upper layer is 1 nm or more.
3 . The photomask blank according to claim 1 , wherein a thickness of the hard mask film is in a range of 4 nm or more and 14 nm or less.
4 . The photomask blank according to claim 1 , wherein the thin film is a light shielding film.
5 . The photomask blank according to claim 4 , further comprising:
between the transparent substrate and the light shielding film, a phase shift film consisting of a material containing silicon.
6 . A photomask to which exposure light having a wavelength of 200 nm or less is applied, the photomask comprising:
a transparent substrate;
a thin film which is formed on the transparent substrate and on which a pattern is formed; and
a hard mask film formed on the thin film,
wherein the thin film is formed of a material containing chromium,
the hard mask film includes a lower layer positioned on a side of the thin film, and an upper layer configuring an outermost layer of the hard mask film,
the lower layer contains at least one selected from tungsten, tellurium, ruthenium, and a compound of tungsten, tellurium, or ruthenium,
the upper layer contains tantalum or a tantalum compound, and
the compound contains at least one selected from oxygen, nitrogen, and carbon.
7 . The photomask according to claim 6 , wherein a thickness of the upper layer is 1 nm or more.
8 . The photomask according to claim 6 , wherein a thickness of the hard mask film is in a range of 4 nm or more and 14 nm or less.
9 . The photomask according to claim 6 , wherein the thin film is a light shielding film.
10 . The photomask according to claim 9 , further comprising:
between the transparent substrate and the light shielding film, a phase shift film consisting of a material containing silicon.
11 . A method for manufacturing a photomask using the photomask blank according to claim 1 , the method comprising:
forming a resist pattern on the hard mask film of the photomask blank;
forming a hard mask pattern by performing dry etching on the hard mask film with a fluorine-based gas using the resist pattern as a mask; and
forming a thin film pattern by performing dry etching on the thin film with a mixed gas of chlorine and oxygen using the hard mask pattern as a mask.
12 . A method for manufacturing a photomask using the photomask blank according to claim 5 , the method comprising:
forming a resist pattern on the hard mask film of the photomask blank;
forming a hard mask pattern by performing dry etching on the hard mask film with a fluorine-based gas using the resist pattern as a mask;
forming a light shielding film pattern by performing dry etching on the light shielding film with a mixed gas of chlorine and oxygen using the hard mask pattern as a mask; and
removing the hard mask pattern while forming a phase shift film pattern by performing dry etching on the phase shift film with a fluorine-based gas using the light shielding film pattern as a mask.
13 . The photomask blank according to claim 2 , wherein a thickness of the hard mask film is in a range of 4 nm or more and 14 nm or less.
14 . The photomask blank according to claim 2 , wherein the thin film is a light shielding film.
15 . The photomask blank according to claim 3 , wherein the thin film is a light shielding film.
16 . The photomask according to claim 7 , wherein a thickness of the hard mask film is in a range of 4 nm or more and 14 nm or less.
17 . The photomask according to claim 7 , wherein the thin film is a light shielding film.
18 . The photomask according to claim 8 , wherein the thin film is a light shielding film.
19 . A method for manufacturing a photomask using the photomask blank according to claim 2 , the method comprising:
forming a resist pattern on the hard mask film of the photomask blank;
forming a hard mask pattern by performing dry etching on the hard mask film with a fluorine-based gas using the resist pattern as a mask; and
forming a thin film pattern by performing dry etching on the thin film with a mixed gas of chlorine and oxygen using the hard mask pattern as a mask.
20 . A method for manufacturing a photomask using the photomask blank according to claim 3 , the method comprising:
forming a resist pattern on the hard mask film of the photomask blank;
forming a hard mask pattern by performing dry etching on the hard mask film with a fluorine-based gas using the resist pattern as a mask; and
forming a thin film pattern by performing dry etching on the thin film with a mixed gas of chlorine and oxygen using the hard mask pattern as a mask.