Photomask blank and photomask

Abstract

A photomask blank is provided comprising an etch stop film which is disposed on a transparent substrate and is resistant to fluorine dry etching and removable by chlorine dry etching, a light-shielding film disposed on the etch stop film and including at least one layer composed of a transition metal/silicon material, and an antireflective film disposed on the light-shielding film. When the light-shielding film is dry etched to form a pattern, pattern size variation arising from pattern density dependency is reduced, so that a photomask is produced at a high accuracy.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view showing one exemplary photomask blank in a first embodiment of the invention, FIG. 1A corresponding to a light-shielding film disposed directly on a transparent substrate and FIG. 1B corresponding to a light-shielding film disposed on a transparent substrate via a phase shift film.

FIG. 2 is a cross-sectional view showing one exemplary photomask blank in a second embodiment of the invention, FIG. 2A corresponding to a light-shielding film disposed directly on a transparent substrate and FIG. 2B corresponding to a light-shielding film disposed on a transparent substrate via a phase shift film.

FIG. 3 is a cross-sectional view showing one exemplary photomask blank in a third embodiment of the invention, FIG. 3A corresponding to a light-shielding film disposed directly on a transparent substrate and FIG. 3B corresponding to a light-shielding film disposed on a transparent substrate via a phase shift film.

FIG. 4 is a cross-sectional view showing one exemplary photomask blank in a fourth embodiment of the invention, FIG. 4A corresponding to a light-shielding film disposed directly on a transparent substrate and FIG. 4B corresponding to a light-shielding film disposed on a transparent substrate via a phase shift film.

FIG. 5 is a cross-sectional view showing one exemplary photomask blank in a fifth embodiment of the invention, FIG. 5A corresponding to a light-shielding film disposed directly on a transparent substrate and FIG. 5B corresponding to a light-shielding film disposed on a transparent substrate via a phase shift film.

FIG. 6 schematically illustrates steps of a method for producing a photomask according to the invention, the method using the photomask blank of the first embodiment and producing a Levenson mask (photomask producing procedure A).

FIG. 7 schematically illustrates steps of a method for producing a photomask according to the invention, the method using the photomask blank of the first embodiment and producing a tritone phase shift mask (photomask producing procedure B).

FIG. 8 schematically illustrates steps of a method for producing a photomask according to the invention, the method using the photomask blank of the second embodiment and producing a Levenson mask (photomask producing procedure C).

FIG. 9 schematically illustrates steps of a method for producing a photomask according to the invention, the method using the photomask blank of the second embodiment and producing a zebra-type chromeless mask (photomask producing procedure D), FIGS. 9A, 9C, 9E, 9G and 9I being cross-sectional views and FIGS. 9B, 9D, 9F, 9H and 9J being plan views.

FIG. 10 schematically illustrates steps of a method for producing a photomask according to the invention, i.e., subsequent steps from FIG. 9 of the method using the photomask blank of the second embodiment and producing a zebra-type chromeless mask (photomask producing procedure D), FIGS. 10A, 10C, 10E, 10G and 10I being cross-sectional views and FIGS. 10B, 10D, 10F, 10H and 10J being plan views.

FIG. 11 schematically illustrates steps of a method for producing a photomask according to the invention, the method using the photomask blank of the second embodiment and producing a tritone phase shift mask (photomask producing procedure E).

FIG. 12 schematically illustrates steps of a method for producing a photomask according to the invention, the method using the photomask blank of the third embodiment and producing a Levenson mask (photomask producing procedure F).

FIG. 13 schematically illustrates steps of a method for producing a photomask according to the invention, the method using the photomask blank of the third embodiment and producing a tritone phase shift mask (photomask producing procedure G).

FIG. 14 schematically illustrates steps of a method for producing a photomask according to the invention, the method using the photomask blank of the fourth embodiment and producing a halftone phase shift mask (photomask producing procedure H).

FIG. 15 schematically illustrates steps of a method for producing a photomask according to the invention, the method using the photomask blank of the fifth embodiment and producing a halftone phase shift mask (photomask producing procedure I).

FIG. 16 is a photomicrograph in cross section of an intermediate sample having an antireflective film, light-shielding film and etch stop film patterned during the production of a Levenson mask in Example 2, showing its light-shielding pattern, and a schematic cross-sectional view of the intermediate sample.

FIG. 17 is a graph showing the results of a CD linearity test of photomask blanks of Example 4 and Comparative Example.

FIG. 18 is a schematic cross-sectional view of a photomask blank in Comparative Example.

Claims

1. A photomask blank from which is produced a photomask comprising a transparent substrate and a mask pattern formed thereon including transparent regions and effectively opaque regions to exposure light, said photomask blank comprising a transparent substrate,an etch stop film disposed on the substrate, optionally with another film intervening therebetween, said etch stop film of single layer or multilayer construction being resistant to fluorine dry etching and removable by chlorine dry etching,a light-shielding film disposed contiguous to said etch stop film and consisting of a single layer composed of a material containing a transition metal and silicon or multiple layers including at least one layer composed of a material containing a transition metal and silicon, andan antireflective film disposed contiguous to said light-shielding film and consisting of a single layer or multiple layers.

2. The photomask blank of claim 1, wherein said etch stop film is composed of chromium alone or a chromium compound containing chromium and at least one element selected from oxygen, nitrogen and carbon.

3. The photomask blank of claim 1, wherein said etch stop film is composed of tantalum alone or a tantalum compound containing tantalum and free of silicon.

4. The photomask blank of claim 1, wherein said etch stop film has a thickness of 2 to 20 nm.

5. The photomask blank of claim 1, wherein the material of which the layer of said light-shielding film is composed contains a transition metal and silicon in a ratio of 1:4-15.

6. The photomask blank of claim 1, wherein the material of which the layer of said light-shielding film is composed is an alloy of a transition metal with silicon or a transition metal silicon compound containing a transition metal, silicon and at least one element selected from oxygen, nitrogen and carbon.

7. The photomask blank of claim 1, wherein the material of which the layer of said light-shielding film is composed is a transition metal silicon compound containing a transition metal, silicon and nitrogen.

8. The photomask blank of claim 7, wherein said light-shielding film has a nitrogen content of 5 atom % to 40 atom %.

9. The photomask blank of claim 1, wherein said light-shielding film consists of multiple layers including a layer composed of a chromium compound containing chromium and at least one element selected from oxygen, nitrogen and carbon.

10. The photomask blank of claim 1, wherein said light-shielding film consists of two layers, a first light-shielding layer formed adjacent to the transparent substrate and a second light-shielding layer formed adjacent to the antireflective film, the first light-shielding layer is composed of a transition metal silicon compound containing a transition metal, silicon and oxygen and/or nitrogen, and the second light-shielding layer is composed of a chromium compound containing chromium and oxygen and/or nitrogen.

11. The photomask blank of claim 1, wherein said light-shielding film consists of multiple layers, among which a layer disposed contiguous to said antireflective film has an extinction coefficient k of at least 1.5 relative to exposure light.

12. The photomask blank of claim 1, wherein said light-shielding film has a thickness of 10 to 80 nm.

13. The photomask blank of claim 1, wherein said antireflective film includes a layer of a transition metal silicon compound containing a transition metal, silicon, and oxygen and/or nitrogen.

14. The photomask blank of claim 1, wherein said antireflective film includes a layer of chromium alone or a chromium compound containing chromium and oxygen and/or nitrogen.

15. The photomask blank of claim 1, wherein said antireflective film consists of two layers, a first antireflective layer formed adjacent to the transparent substrate and a second antireflective layer formed remote from the transparent substrate, the first antireflective layer is composed of a transition metal silicon compound comprising a transition metal, silicon and oxygen and/or nitrogen, and the second antireflective layer is composed of a chromium compound containing chromium and oxygen and/or nitrogen.

16. The photomask blank of claim 14, wherein in said antireflective film, the layer of chromium compound has a chromium content of at least 50 atom %.

17. The photomask blank of claim 1, further comprising an etching mask film disposed contiguous to said antireflective film and consisting of a single layer or multiple layers which are resistant to fluorine dry etching and removable by chlorine dry etching.

18. The photomask blank of claim 17, wherein said etching mask film is composed of chromium alone or a chromium compound containing chromium and at least one element selected from oxygen, nitrogen and carbon.

19. The photomask blank of claim 17, wherein said etching mask film has a thickness of 2 to 30 nm.

20. The photomask blank of claim 1, wherein said transition metal is at least one element selected from the group consisting of titanium, vanadium, cobalt, nickel, zirconium, niobium, molybdenum, hafnium, tantalum, and tungsten.

21. The photomask blank of claim 1, wherein said transition metal is molybdenum.

22. The photomask blank of claim 1, wherein a phase shift film intervenes as the other film.

23. The photomask blank of claim 22, wherein said phase shift film is a halftone phase shift film.

24. A photomask obtained by patterning the photomask blank of claim 1.