Photomask blank and making method, photomask, light pattern exposure method, and design method of transition metal/silicon base material film

1. A photomask blank comprising a transparent substrate and a transition metal/silicon base material film of a material comprising a transition metal, silicon, oxygen and nitrogen, disposed on the substrate, wherein

said transition metal/silicon base material film has an oxygen content of at least 3 atom % and is constructed by a layer of a transition metal/silicon base material satisfying the following formula (1):

4× C Si /100−6× C M /100>1   (1)

wherein C Si is a silicon content in atom % and C M is a transition metal content in atom %, a multilayer structure having at least two such layers stacked, or a combination of such a layer or a multilayer structure with a surface oxidized layer disposed remote from the substrate and having a thickness of up to 10 nm.

2. A photomask blank comprising a transparent substrate and a transition metal/silicon base material film of a material comprising a transition metal, silicon, oxygen and nitrogen, disposed on the substrate, wherein

said transition metal/silicon base material film has an oxygen content of at least 3 atom % and is constructed by a layer of a transition metal/silicon base material satisfying the following formula (2):

4× C Si /100−6× C M /100−3× C N /100>−0.1   (2)

wherein C Si is a silicon content in atom %, C M is a transition metal content in atom %, and C N is a nitrogen content in atom %, a multilayer structure having at least two such layers stacked, or a combination of such a layer or a multilayer structure with a surface oxidized layer disposed remote from the substrate and having a thickness of up to 10 nm.

3. A photomask blank comprising a transparent substrate and a transition metal/silicon base material film of a material comprising a transition metal, silicon, oxygen and nitrogen, disposed on the substrate, wherein

said transition metal/silicon base material film has an oxygen content of at least 3 atom % and is constructed by a layer of a transition metal/silicon base material satisfying the following formula (3):

4× C Si /100−6× C M /100−3× C N /100+2× C O /100>0   (3)

wherein C Si is a silicon content in atom %, C M is a transition metal content in atom %, C N is a nitrogen content in atom %, C O is an oxygen content in atom %, a multilayer structure having at least two such layers stacked, or a combination of such a layer or a multilayer structure with a surface oxidized layer disposed remote from the substrate and having a thickness of up to 10 nm.

4. The photomask blank of any one of claims 1 to 3 wherein the transition metal is molybdenum.

5. The photomask blank of any one of claims 1 to 3 wherein the surface oxidized layer is formed by air oxidation or forced oxidative treatment of a sub-surface region of the layer of the transition metal/silicon base material.

6. The photomask blank of any one of claims 1 to 3 wherein said transition metal/silicon base material film is a halftone phase shift film.

7. A photomask prepared from the photomask blank of any one of claims 1 to 3 .

8. A light pattern exposure method comprising irradiating ArF excimer laser light to an object through the photomask of claim 7 to expose the object to a pattern of light.

9. The light pattern exposure method of claim 8 wherein ArF excimer laser light is irradiated through the photomask to expose the object to a pattern of light after the photomask has been irradiated in a cumulative dose of at least 10 kJ/cm 2 .

10. In connection with a photomask having formed thereon a pattern of a transition metal/silicon base material film of a material comprising a transition metal, silicon, oxygen and nitrogen,

a method for designing the transition metal/silicon base material film such that the film pattern may be restrained in pattern line width variation degradation by irradiation of ArF excimer laser light, the method comprising the steps of:

providing the transition metal/silicon base material film with an oxygen content of at least 3 atom %,

constructing the transition metal/silicon base material film by a layer of a transition metal/silicon base material, a multilayer structure having at least two such layers stacked, or a combination of such a layer or a multilayer structure with a surface oxidized layer disposed remote from the substrate and having a thickness of up to 10 nm, and

selecting a silicon content C Si and a transition metal content C M of the transition metal/silicon base material so as to satisfy the following formula (1):

4× C Si /100−6× C M /100>1   (1)

wherein C Si is a silicon content in atom % and C M is a transition metal content in atom %.

11. In connection with a photomask having formed thereon a pattern of a transition metal/silicon base material film of a material comprising a transition metal, silicon, oxygen and nitrogen,

a method for designing the transition metal/silicon base material film such that the film pattern may be restrained in pattern line width variation degradation by irradiation of ArF excimer laser light, the method comprising the steps of:

providing the transition metal/silicon base material film with an oxygen content of at least 3 atom %,

constructing the transition metal/silicon base material film by a layer of a transition metal/silicon base material, a multilayer structure having at least two such layers stacked, or a combination of such a layer or a multilayer structure with a surface oxidized layer disposed remote from the substrate and having a thickness of up to 10 nm, and

selecting a silicon content C Si , a transition metal content C M , and a nitrogen content C N of the transition metal/silicon base material so as to satisfy the following formula (2):

4× C Si /100−6× C M /100−3× C N /100>−0.1   (2)

wherein C Si is a silicon content in atom %, C M is a transition metal content in atom %, and C N is a nitrogen content in atom %.

12. In connection with a photomask having formed thereon a pattern of a transition metal/silicon base material film of a material comprising a transition metal, silicon, oxygen and nitrogen,

a method for designing the transition metal/silicon base material film such that the film pattern may be restrained in pattern line width variation degradation by irradiation of ArF excimer laser light, the method comprising the steps of:

providing the transition metal/silicon base material film with an oxygen content of at least 3 atom %,

constructing the transition metal/silicon base material film by a layer of a transition metal/silicon base material, a multilayer structure having at least two such layers stacked, or a combination of such a layer or a multilayer structure with a surface oxidized layer disposed remote from the substrate and having a thickness of up to 10 nm, and

selecting a silicon content C Si , a transition metal content C M , a nitrogen content C N , and an oxygen content C O of the transition metal/silicon base material so as to satisfy the following formula (3):

4× C Si /100−6× C M /100−3× C N /100+2× C O /100>0   (3)

wherein C Si is a silicon content in atom %, C M is a transition metal content in atom %, C N is a nitrogen content in atom %, C O is an oxygen content in atom %.

13. The designing method of any one of claims 10 to 12 wherein the transition metal is molybdenum.

14. The designing method of any one of claims 10 to 12 wherein the surface oxidized layer is formed by air oxidation or forced oxidative treatment of a sub-surface region of the layer of the transition metal/silicon base material.

15. The designing method of any one of claims 10 to 12 wherein said transition metal/silicon base material film is a halftone phase shift film.

16. A method for preparing a photomask blank, comprising the step of depositing a transition metal/silicon base material film as designed by the designing method of any one of claims 10 to 12 on a transparent substrate.