1. A mask blank having a layer to be a phase shift mask, the mask blank having:

a phase shift layer laminated on the transparent substrate;

an etch stop layer disposed at a position farther from the transparent substrate than the phase shift layer; and

a light-shielding layer provided at a position farther from the transparent substrate than the etching stopper layer,

the phase-shift layer contains chromium and,

the light-shielding layer contains chromium and oxygen,

the etching stop layer contains molybdenum silicide and nitrogen, and has a peak region where the nitrogen concentration reaches a peak at a position close to the light-shielding layer in the film thickness direction.

2. The mask blank according to claim 1, wherein,

the etching stopper layer has the peak region on an upper surface close to the light-shielding layer in a film thickness direction.

3. The mask blank according to claim 1, wherein,

the resistivity in the peak region of the etch stop layer was set to 1.0 × 10^-3Omega cm or more.

4. The mask blank according to claim 2,

the resistivity in the peak region of the etch stop layer was set to 1.0 × 10^-3Omega cm or more.

5. Mask blank according to any one of claims 1 to 4,

the nitrogen concentration in the peak region of the etch stop layer is set to 30 atomic% or more.

6. Mask blank according to any one of claims 1 to 4,

the silicon concentration in the peak region of the etch stop layer is set to 35 atomic% or less.

7. Mask blank according to any one of claims 1 to 4,

the molybdenum concentration in the peak region of the etch stop layer is set to 30 atomic% or less.

8. Mask blank according to any one of claims 1 to 4,

the film thickness of the peak region is set to be within 1/3 of the film thickness of the etching stop layer.

9. Mask blank according to any one of claims 1 to 4,

the resistivity of the etching stop layer other than the peak region is set to 1.0 × 10^-3Omega cm or less.

10. Mask blank according to any one of claims 1 to 4,

the etch stop layer is set to have a nitrogen concentration of 25 atomic% or less excluding the peak region.

11. Mask blank according to any one of claims 1 to 4,

the composition ratio of molybdenum to silicon of the etch stop layer other than the peak region is set to 1 ≦ Si/Mo.

12. Mask blank according to any one of claims 1 to 4,

the thickness of the etching stop layer is set to be in the range of 10nm to 100 nm.

13. A method for manufacturing a mask blank according to any one of claims 1 to 12, comprising:

a phase shift layer forming step of laminating the phase shift layer containing chromium on the transparent substrate;

an etching stop layer forming step of laminating the etching stop layer containing molybdenum silicide and nitrogen at a position farther from the transparent substrate than the phase shift layer; and

a light-shielding layer forming step of laminating the light-shielding layer containing chromium and oxygen at a position farther from the transparent substrate than the etching stopper layer,

in the etching stop layer forming step, the etching stop layer is formed by controlling the nitrogen concentration in the peak region in the film thickness direction by setting the partial pressure of the nitrogen-containing gas as a supply gas during sputtering.

14. The method for manufacturing a mask blank according to claim 13,

in the etching stop layer forming step, the partial pressure of the nitrogen-containing gas is set so as to increase the sheet resistance in the etching stop layer with an increase in the nitrogen content.

15. The method for manufacturing a mask blank according to claim 14, wherein,

in the etching stopper layer forming step, the peak region is formed by setting a partial pressure ratio of the nitrogen-containing gas to a range of 30% or more.

16. The method for manufacturing a mask blank according to claim 15, wherein,

in the step of forming the etching stopper layer, the nitrogen-containing gas is N₂。

17. The method for manufacturing a mask blank according to any one of claims 13 to 16, wherein,

in the etching stop layer forming step, a target in which the composition ratio of molybdenum to silicon is set to 2.3. ltoreq. Si/Mo. ltoreq.3.0 is used.

18. A phase shift mask manufactured from the mask blank of any one of claims 1 to 12.

19. A method of manufacturing a phase shift mask according to claim 18, comprising:

a phase shift pattern forming step of forming a pattern on the phase shift layer;

an etching stop pattern forming step of forming a pattern on the etching stop layer; and

a light-shielding pattern forming step of forming a pattern on the light-shielding layer,

the etching solution in the phase shift pattern forming step and the light shielding pattern forming step is different from the etching solution in the etching stop pattern forming step.

Background

In recent years, in Flat Panel Displays (FPDs) such as liquid crystal displays and organic EL displays, panels have been increasingly refined. With the high definition of the panel, the miniaturization of the photomask is also progressing. Therefore, not only the necessity of a mask using a light-shielding film, which has been conventionally used, but also the necessity of an edge-enhanced phase shift mask have been increased.

In FPDs and the like, miniaturization is required for both the Line pitch (Line & Space) and the contact hole pattern. A phase shift mask is required to form a fine pattern.

For example, a contact hole pattern requires a large contrast at the time of exposure, and a rim-type phase shift mask is sometimes used. The rim type phase shift mask is constructed by forming a phase shift layer using a chromium compound on a quartz substrate, forming an etching stopper layer using a molybdenum silicide compound on the phase shift layer, and forming a light shielding layer using a metal film such as a chromium film on the etching stopper layer.

For a large mask used for an FPD or the like, WET etching is generally used for patterning. As an etching stopper film used for such WET etching, an etching stopper film formed of a silicide film such as a molybdenum silicide film is known (patent document 1).

Patent document 1: international publication No. 2013/190786

When the etching stopper film is formed of a silicide film such as a molybdenum silicide film, hydrofluoric acid is contained in the etching solution for the molybdenum silicide film. Therefore, a problem arises in that the quartz substrate is etched during WET etching of the molybdenum silicide film, and the optical characteristics of the phase shift mask change.

Further, if an appropriate etching stopper film is not used, etching proceeds excessively at the interface between the etching stopper film and the light-shielding film at the time of patterning. Therefore, it was also found that there was a problem that the etching stopper film disappeared and the sectional shape became abnormal after the etching.

Disclosure of Invention

The present invention has been made in view of the above circumstances, and it is desirable to achieve the following object.

1. The etching of the layer on the upper side of the etching stop layer has good etching stop performance.

2. In etching the etching stop layer, influence on other portions is suppressed.

3. Suppressing electrostatic destruction.

4. The accuracy of the shape in patterning is improved.

5. High definition in mask manufacturing can be achieved.

The mask blank of the present invention is a mask blank having a layer to be a phase shift mask, and has: a phase shift layer laminated on the transparent substrate; an etch stop layer disposed at a position farther from the transparent substrate than the phase shift layer; and a light-shielding layer provided at a position farther from the transparent substrate than the etching stopper layer, the phase shift layer containing chromium, the light-shielding layer containing chromium and oxygen, the etching stopper layer containing molybdenum silicide and nitrogen, and having a peak region where a nitrogen concentration reaches a peak at a position close to the light-shielding layer in a film thickness direction. Thereby, the above-described problems are solved.

In the mask blank of the present invention, the etching stopper layer may have the peak region on an upper surface close to the light shielding layer in a film thickness direction.

In the mask blank of the present invention, the resistivity in the peak region of the etch stop layer may be set to 1.0 × 10^-3Omega cm or more.

In the present invention, it is preferable that the nitrogen concentration in the peak region of the etching stopper layer is set to 30 atomic% or more.

In the mask blank of the present invention, a method in which the silicon concentration in the peak region of the etch stop layer is set to 35 atomic% or less can also be employed.

In the mask blank of the present invention, the molybdenum concentration in the peak region of the etch stop layer may be set to 30 atomic% or less.

In the mask blank of the present invention, the film thickness of the peak region may be set to a range of 1/3 or less of the film thickness of the etching stopper layer.

In the mask blank of the present invention, the resistivity of the etch stop layer other than the peak region may be set to 1.0 × 10^-3Omega cm or less.

In the mask blank of the present invention, the nitrogen concentration of the etch stop layer other than the peak region may be set to 25 atomic% or less.

In the mask blank of the present invention, the composition ratio of molybdenum to silicon of the etch stop layer other than the peak region may be set to 1. ltoreq. Si/Mo.

In the mask blank of the present invention, the film thickness of the etching stopper layer may be set in a range of 10nm to 100 nm.

The method of manufacturing a mask blank according to the present invention is the method of manufacturing a mask blank according to any one of the above, and may include: a phase shift layer forming step of laminating the phase shift layer containing chromium on the transparent substrate; an etching stop layer forming step of laminating the etching stop layer containing molybdenum silicide and nitrogen at a position farther from the transparent substrate than the phase shift layer; and a light-shielding layer forming step of forming the etching stopper layer by stacking the light-shielding layer containing chromium and oxygen at a position farther from the transparent substrate than the etching stopper layer, wherein the partial pressure of a nitrogen-containing gas as a supply gas during sputtering is set to control the nitrogen concentration in the peak region in the film thickness direction.

In the method for manufacturing a mask blank according to the present invention, in the etching stop layer forming step, the partial pressure of the nitrogen-containing gas may be set so as to increase the sheet resistance in the etching stop layer with an increase in the nitrogen content.

In the method for manufacturing a mask blank according to the present invention, the peak region may be formed by setting a partial pressure ratio of the nitrogen-containing gas to a range of 30% or more in the etch stop layer forming step.

In the method for manufacturing a mask blank according to the present invention, in the etching stopper layer forming step, the nitrogen-containing gas may be N₂。

In the method for manufacturing a mask blank according to the present invention, a target having a composition ratio of molybdenum to silicon of 2.3. ltoreq. Si/Mo. ltoreq.3.0 may be used in the etching stopper layer forming step.

The phase shift mask of the present invention can be manufactured from any of the mask blanks described above.

A method for manufacturing a phase shift mask blank according to the present invention is a method for manufacturing a phase shift mask, including: a phase shift pattern forming step of forming a pattern on the phase shift layer; an etching stop pattern forming step of forming a pattern on the etching stop layer; and a light-shielding pattern forming step of forming a pattern on the light-shielding layer, wherein an etching solution in the phase shift pattern forming step and the light-shielding pattern forming step is different from an etching solution in the etching stop pattern forming step.

The mask blank of the present invention is a mask blank having a layer to be a phase shift mask, and has: a phase shift layer laminated on a transparent substrate, an etching stop layer provided at a position farther from the transparent substrate than the phase shift layer; and a light-shielding layer provided at a position farther from the transparent substrate than the etching stopper layer. The phase shift layer contains chromium, the light-shielding layer contains chromium and oxygen, and the etching stopper layer contains molybdenum silicide and nitrogen and has a peak region where the nitrogen concentration reaches a peak at a position close to the light-shielding layer in the film thickness direction.

This can improve chemical resistance on the surface of the etching stopper layer in etching the light-shielding layer. Therefore, the adhesion between the light-shielding layer and the etching stopper layer can be improved, and the accuracy of the cross-sectional shape can be improved in the etching of the light-shielding layer, thereby improving the accuracy of the shape of the mask pattern.

In addition, in the etching of the etching stopper layer, the etching rate in the etching stopper layer can be increased (E.R.). Therefore, the etching time in the etching stopper layer can be shortened, and the influence of etching on the transparent substrate used as a glass substrate can be reduced. This is because the glass substrate may be exposed when the etching stopper layer is etched, and the etchant for the etching stopper layer containing molybdenum silicon may act on the exposed portion. Meanwhile, the etch stop layer can be reliably removed by etching.

In the mask blank of the present invention, the etching stopper layer has the peak region on an upper surface close to the light shielding layer in a film thickness direction.

This can improve chemical resistance on the surface of the etching stopper layer in etching the light-shielding layer. Therefore, the adhesion between the light-shielding layer and the etching stopper layer can be improved, and the accuracy of the cross-sectional shape can be improved in the etching of the light-shielding layer, thereby improving the accuracy of the shape of the mask pattern.

Further, in the etching of the etching stopper layer, the etching rate in the etching stopper layer can be increased (E.R.) after the peak region is removed. Therefore, the etching time in the etching stopper layer can be shortened, and the influence of etching on the transparent substrate used as a glass substrate can be reduced.

In the mask blank of the present invention, the resistivity in the peak region of the etch stop layer is set to 1.0 × 10^-3Omega cm or more.

This can improve chemical resistance on the surface of the etching stopper layer in etching the light-shielding layer. Therefore, a mask having a good cross-sectional shape can be formed.

Further, particles adhering to the surface of the etching stopper layer can be reduced. This can suppress the occurrence of pinholes.

In the present invention, the nitrogen concentration in the peak region of the etch stop layer is set to 30 atomic% or more.

Thus, by setting the sheet resistance in the peak region in the above range, the chemical resistance on the surface of the etching stopper layer can be improved in the etching of the light-shielding layer. Therefore, a mask having a good cross-sectional shape can be formed.

Further, particles adhering to the surface of the etching stopper layer can be reduced. This can suppress the occurrence of pinholes.

In the mask blank of the present invention, the silicon concentration in the peak region of the etch stop layer is set to 35 atomic% or less.

Thus, a mask blank capable of forming a phase shift mask having a satisfactory cross-sectional shape can be provided.

In the mask blank of the present invention, the molybdenum concentration in the peak region of the etch stop layer is set to 30 atomic% or less.

Thus, a mask blank capable of forming a phase shift mask having a satisfactory cross-sectional shape can be provided.

In the mask blank of the present invention, the film thickness of the peak region is set to be within a range of 1/3 or less of the film thickness of the etching stopper layer.

This makes it possible to achieve both sufficient etching stop properties in the etching stop layer and a high etching rate (E.R.) in the etching stop layer. Therefore, in the etching of the light shielding layer, the chemical resistance on the surface of the etching stopper layer can be increased, and in the etching of the etching stopper layer, the etching rate in the etching stopper layer can be increased after the peak region is removed (E.R.).

In the mask blank of the present invention, the resistivity of the etch stop layer other than the peak region is set to 1.0 × 10^-3Omega cm or less.

This makes it possible to increase the etching rate (E.R.) in the etching of the etching stopper layer after the peak region is removed. Therefore, the etching time in the etching stopper layer can be shortened, and the influence of etching on the transparent substrate used as a glass substrate can be reduced.

Further, by using a molybdenum silicide film having a low resistivity as an etching stopper layer, electrostatic breakdown can be suppressed.

In the mask blank of the present invention, the nitrogen concentration of the etch stop layer other than the peak region is set to 25 atomic% or less.

This can increase the etching rate (E.R.) in the etching stop layer closer to the phase shift layer than the peak region. Therefore, the etching time in the etching stopper layer can be shortened, and the influence of etching on the transparent substrate used as a glass substrate can be reduced.

Further, by using a molybdenum silicide film having a low resistivity as an etching stopper layer, electrostatic breakdown can be suppressed.

In the mask blank of the present invention, the composition ratio of molybdenum to silicon of the etch stop layer other than the peak region is set to 1. ltoreq. Si/Mo.

Thus, a mask blank capable of forming a phase shift mask having a satisfactory cross-sectional shape can be provided.

In the mask blank of the present invention, the thickness of the etching stopper layer is set in the range of 10nm to 100 nm.

Thus, a mask blank capable of forming a phase shift mask having a satisfactory cross-sectional shape can be provided.

A method for manufacturing a mask blank according to the present invention is a method for manufacturing a mask blank according to any one of the above methods, comprising: a phase shift layer forming step of laminating the phase shift layer containing chromium on the transparent substrate; an etching stop layer forming step of laminating the etching stop layer containing molybdenum silicide and nitrogen at a position farther from the transparent substrate than the phase shift layer; and a light-shielding layer forming step of laminating the light-shielding layer containing chromium and oxygen at a position farther from the transparent substrate than the etching stopper layer. In the etching stop layer forming step, the etching stop layer is formed by controlling the nitrogen concentration in the peak region in the film thickness direction by setting the partial pressure of the nitrogen-containing gas as a supply gas during sputtering.

In the method for manufacturing a mask blank according to the present invention, in the etching stop layer forming step, the sheet resistance in the etching stop layer is increased with an increase in the nitrogen content by setting the partial pressure of the nitrogen-containing gas.

Thus, it is possible to manufacture a mask blank having an etching stopper layer having a higher nitrogen concentration at a position closer to the light-shielding layer than at a position closer to the phase-shift layer in the film thickness direction.

In addition, a peak region in which the nitrogen concentration reaches a peak can be formed in the etching stopper layer in the vicinity of the interface with the light-shielding layer. In addition, in the etching stopper layer, the nitrogen concentration at a position close to the phase shift layer can be reduced compared with the nitrogen concentration in the peak region. Further, while the etching stopper layer is formed by sputtering, the etching stopper layer having such a structure can be realized by controlling the partial pressure of the nitrogen-containing gas in the atmosphere gas.

Therefore, a mask blank having a sufficient etching stop capability and capable of forming a phase shift mask having a good cross-sectional shape can be manufactured.

In the method for manufacturing a mask blank according to the present invention, in the etching stopper layer forming step, the peak region is formed by setting a partial pressure ratio of the nitrogen-containing gas to a range of 30% or more.

This makes it possible to set the peak region in the etching stopper layer to a predetermined nitrogen concentration and to form the sheet resistance.

In the method for manufacturing a mask blank according to the present invention, in the etching stopper layer forming step, the nitrogen-containing gas is N₂。

This makes it possible to set the peak region in the etching stopper layer to a predetermined nitrogen concentration and to form the etching stopper layer to have the above-described resistivity.

In the method for manufacturing a mask blank according to the present invention, in the etching stopper layer forming step, a target in which the composition ratio of molybdenum to silicon is set to 2.3. ltoreq. Si/Mo. ltoreq.3.0 is used.

Thus, a mask blank can be manufactured which can have a predetermined nitrogen concentration in the peak region of the etching stopper layer, can be formed to have the sheet resistance, has a sufficient etching stopper ability, and can form a phase shift mask having a good cross-sectional shape.

The phase shift mask of the present invention is manufactured from the mask blank described in any one of the above. Thus, a phase shift mask having a sufficient etching stop capability and a good cross-sectional shape can be provided.

A method for manufacturing a phase shift mask blank according to the present invention is a method for manufacturing a phase shift mask, including: a phase shift pattern forming step of forming a pattern on the phase shift layer; an etching stop pattern forming step of forming a pattern on the etching stop layer; and a light-shielding pattern forming step of forming a pattern on the light-shielding layer. The etching solution in the phase shift pattern forming step and the light shielding pattern forming step is different from the etching solution in the etching stop pattern forming step. Thus, a phase shift mask having a sufficient etching stop capability and a good cross-sectional shape can be formed.

According to the present invention, the following effects can be achieved: that is, it is possible to provide a mask blank capable of forming a phase shift mask having a good cross-sectional shape while reducing the influence on the surface of a glass substrate.

Drawings

Fig. 1 is a sectional view showing a mask blank according to a first embodiment of the present invention.

Fig. 2 is a sectional view showing a method of manufacturing a mask blank according to a first embodiment of the present invention.

Fig. 3 is a sectional view showing steps of a method for manufacturing a phase shift mask according to a first embodiment of the present invention.

Fig. 4 is a sectional view showing steps of a method for manufacturing a phase shift mask according to a first embodiment of the present invention.

Fig. 5 is a sectional view showing steps of a method for manufacturing a phase shift mask according to a first embodiment of the present invention.

Fig. 6 is a sectional view showing steps of a method for manufacturing a phase shift mask according to a first embodiment of the present invention.

Fig. 7 is a sectional view showing steps of a method for manufacturing a phase shift mask according to a first embodiment of the present invention.

Fig. 8 is a sectional view showing steps of a method for manufacturing a phase shift mask according to a first embodiment of the present invention.

Fig. 9 is a sectional view showing steps of a method for manufacturing a phase shift mask according to a first embodiment of the present invention.

Fig. 10 is a cross-sectional view showing a phase shift mask according to a first embodiment of the present invention.

Fig. 11 is a schematic view showing a film deposition apparatus in the method for manufacturing a mask blank according to the first embodiment of the present invention.

Fig. 12 is a graph showing a relationship between an etching rate (E.R.) of an etching stopper layer and a nitrogen concentration in the mask blank and the method of manufacturing a phase shift mask according to the first embodiment of the present invention.

Fig. 13 is a graph showing the composition ratio in the film thickness direction of the etching stopper layer in the mask blank and the phase shift mask according to the first embodiment of the present invention.

Detailed Description

Next, a mask blank, a phase shift mask, and a manufacturing method according to a first embodiment of the present invention will be described with reference to the drawings.

Fig. 1 is a sectional view showing a mask blank according to the present embodiment, fig. 2 is a sectional view showing a mask blank according to the present embodiment, and reference numeral 10B in fig. 1 and 2 denotes a mask blank.

The mask blank 10B according to the present embodiment is provided to a phase shift mask (photomask) used in a range where the wavelength of exposure light is approximately 365nm to 436 nm. As shown in fig. 1, a mask blank 10B according to the present embodiment includes: a glass substrate (transparent substrate) 11; a phase shift layer 12 formed on the glass substrate 11; an etch stop layer 13 formed on the phase shift layer 12; and a light-shielding layer 14 formed on the etching stopper layer 13.

That is, the etching stopper layer 13 is provided at a position farther from the glass substrate 11 than the phase shift layer 12. The light-shielding layer 14 is provided at a position farther from the glass substrate 11 than the etching stopper layer 13.

These phase shift layer 12, etching stop layer 13, and light shielding layer 14 constitute a mask layer which is a laminated film having optical characteristics required for a photomask.

As shown in fig. 2, the mask blank 10B according to the present embodiment may be configured such that a photoresist layer 15 is formed in advance on a mask layer in which the phase shift layer 12, the etching stopper layer 13, and the light shielding layer 14 are laminated as shown in fig. 1.

The mask blank 10B according to the present embodiment may have a structure in which an antireflection layer, a chemical-resistant layer, a protective layer, an adhesion layer, and the like are laminated in addition to the phase shift layer 12, the etching stopper layer 13, and the light shielding layer 14. Further, as shown in fig. 2, a photoresist layer 15 may be formed on these laminated films.

As the glass substrate 11, a material excellent in transparency and optical isotropy can be used, and for example, a quartz glass substrate can be used. The size of the glass substrate 11 is not particularly limited, and may be appropriately selected depending on a substrate to be exposed using the mask (for example, a substrate for an FPD such as an LCD (liquid crystal display), a plasma display, or an organic EL (electroluminescence) display).

In the present embodiment, as the glass substrate 11, a rectangular substrate having a side of about 100mm to a side of 2000mm or more can be used, and a substrate having a thickness of 1mm or less, a substrate having a thickness of several millimeters, or a substrate having a thickness of 10mm or more can be used.

In addition, the flatness of the glass substrate 11 may also be reduced by polishing the surface of the glass substrate 11. The flatness of the transparent substrate 11 may be 20 μm or less, for example. This makes it possible to increase the depth of focus of the mask, and to contribute significantly to fine and highly accurate pattern formation. Further, the flatness is preferably a small value of 10 μm or less.

The phase shift layer 12 is a layer containing Cr (chromium) as a main component, and contains C (carbon), O (oxygen), and N (nitrogen).

Further, the phase shift layer 12 may have a different composition in the thickness direction. In this case, the phase shift layer 12 may be configured by laminating one or more selected from Cr alone and Cr oxides, nitrides, carbides, oxynitrides, carbonitrides, and oxycarbonitrides.

As described later, the phase shift layer 12 has a thickness and a composition ratio (atomic%) of Cr, N, C, O, and the like set so as to obtain predetermined optical characteristics and resistivity.

The film thickness of the phase shift layer 12 is set in accordance with optical characteristics required for the phase shift layer 12, and varies depending on the composition ratio of Cr, N, C, O, and the like. The thickness of the phase shift layer 12 may be 50nm to 150 nm.

For example, the composition ratio in the phase shift layer 12 may be set to 2.3 atomic% to 10.3 atomic% in carbon content (carbon concentration), 8.4 atomic% to 72.8 atomic% in oxygen content (oxygen concentration), 1.8 atomic% to 42.3 atomic% in nitrogen content (nitrogen concentration), and 20.3 atomic% to 42.4 atomic% in chromium content (chromium concentration).

Thus, when the refractive index is about 2.4 to 3.1 and the extinction coefficient is 0.3 to 2.1 in the wavelength range of 365nm to 436nm, the phase shift layer 12 can be set to a film thickness of about 90 nm.

The composition ratio and the film thickness of the phase shift layer 12 are set in accordance with the optical characteristics required for the phase shift mask 10 to be manufactured, and are not limited to the above values.

The etch stop layer 13 is made of a material different from that of the phase shift layer 12, and may be a metal silicide film, for example, a film containing a metal such as Ta (tantalum), Ti (titanium), W (tungsten), Mo (molybdenum), Zr (zirconium), or an alloy of these metals and silicon. In particular, among the metal silicide films, molybdenum silicide film is preferably used, and MoSi is exemplified_X(X.gtoreq.2) film (e.g., MoSi₂Film, MoSi₃Film or MoSi₄Films, etc.).

The etching stopper layer 13 is preferably a molybdenum silicide film containing O (oxygen), N (nitrogen), and C (carbon).

Further, the etching stopper layer 13 may contain C (carbon).

In the etching stopper layer 13, the oxygen content (oxygen concentration) may be set to a range of 2.6 atomic% to 10.9 atomic%, the nitrogen content (nitrogen concentration) may be set to a range of 1.5 atomic% to 40.9 atomic%, and the carbon content (carbon concentration) may be set to a range of 2.4 atomic% to 4.3 atomic%.

The film thickness of the etching stopper layer 13 may be set in the range of 10nm to 100 nm.

The etching stopper layer 13 has a peak region 13A where the nitrogen concentration reaches a peak at a position close to the light-shielding layer 14 in the film thickness direction.

The etching stopper layer 13 has a nitrogen concentration lower than that of the peak region 13A at a position close to the phase shift layer 12 in the film thickness direction.

The peak region 13A may be exposed on the upper surface of the etching stopper layer 13 close to the light-shielding layer 14 in the film thickness direction. That is, the peak region 13A is formed at the interface between the etching stopper layer 13 and the light shielding layer 14.

The resistivity in the peak region 13A of the etch stop layer 13 was set to 1.0 × 10^-3Omega cm or more.

The nitrogen concentration in the peak region 13A of the etching stopper layer 13 is set to 30 atomic% or more.

The silicon concentration in the peak region 13A of the etching stopper layer 13 is set to be in the range of 20 atomic% to 70 atomic%.

The molybdenum concentration in the peak region 13A of the etching stopper layer 13 is set in the range of 20 atomic% to 40 atomic%.

The film thickness of the peak region 13A is set to be within 1/3 or less of the film thickness of the etching stopper layer 13.

The resistivity of the etching stopper layer 13 at a position other than the peak region 13A, i.e., closer to the phase shift layer 12 than the peak region 13A, is set to 1.0X 10^-3Omega cm or less.

The nitrogen concentration in the etching stopper layer 13 is set to 25 atomic% or less at a position other than the peak region 13A, that is, at a position closer to the phase shift layer 12 than the peak region 13A.

The composition ratio of molybdenum to silicon in the etching stopper layer 13 excluding the peak region 13A, i.e., in a position closer to the phase shift layer 12 than the peak region 13A, is set to 1. ltoreq. Si/Mo.

Note that the nitrogen concentration in the etching stopper layer 13 other than the peak region 13A, that is, in a position closer to the phase shift layer 12 than the peak region 13A may be a uniform constant value, may have a gradient, or may have a predetermined change in the film thickness direction, as long as it is lower than the nitrogen concentration in the peak region 13A.

In addition, as for the etching stopper layer 13, as long as the peak region 13A has a portion with a high nitrogen concentration, it is preferable that the nitrogen concentration is as low as possible and the etching rate (E.R.) is large in the other portion. In addition, as for the etching stopper layer 13, as long as the peak region 13A has a portion with a high nitrogen concentration, it is preferable that the nitrogen concentration is as low as possible and the resistivity is low in the other portion.

The light-shielding layer 14 is a layer containing Cr (chromium) and O (oxygen) as main components, and contains C (carbon) and N (nitrogen).

In this case, the light shielding layer 14 may be formed by laminating one or more selected from Cr oxides, nitrides, carbides, oxynitrides, carbonitrides, and oxycarbonitrides. The light-shielding layer 14 may have a different composition in the thickness direction.

As described later, the thickness of the light-shielding layer 14 and the composition ratio (atomic%) of Cr, N, C, O, Si, and the like are set so as to obtain predetermined adhesiveness (water repellency) and predetermined optical characteristics with respect to the light-shielding layer 14.

The film thickness of the light-shielding layer 14 is set according to the conditions required for the light-shielding layer 14, that is, film characteristics such as adhesion (water repellency) and optical characteristics between the photoresist layer 15 and the light-shielding layer 14, which will be described later. The film characteristics of the light-shielding layer 14 vary depending on the composition ratio of Cr, N, C, O, and the like. In particular, the film thickness of the light-shielding layer 14 can be set according to the optical characteristics required for the phase shift mask 10.

By setting the film thickness and composition of the light-shielding layer 14 as described above, adhesion between the photoresist layer 15 used for, for example, chromium and the light-shielding layer 14 is improved in patterning by photolithography. Thus, the etching solution does not enter the interface between the photoresist layer 15 and the light-shielding layer 14. Therefore, a good pattern shape can be obtained, and a desired pattern can be formed.

Further, when the light-shielding layer 14 is not set as described above, it is not preferable that the adhesion between the photoresist layer 15 and the light-shielding layer 14 is not in a predetermined state, and the etching solution enters the interface due to peeling of the photoresist layer 15, so that patterning cannot be performed. Further, if the film thickness of the light-shielding layer 14 is not set as described above, it is difficult to set the optical characteristics of the photomask to desired conditions, or the cross-sectional shape of the mask pattern may not be in a desired state, which is not preferable.

The light-shielding layer 14 can reduce hydrophilicity by increasing the oxygen concentration and the nitrogen concentration in the chromium compound, and can improve hydrophobicity and adhesion.

Meanwhile, the light-shielding layer 14 can be decreased in the values of the refractive index and the extinction coefficient by increasing the oxygen concentration and the nitrogen concentration in the chromium compound, or can be increased in the values of the refractive index and the extinction coefficient by decreasing the oxygen concentration and the nitrogen concentration in the chromium compound.

In the method of manufacturing the mask blank according to the present embodiment, the phase shift layer 12 is formed on the glass substrate 11, the etching stopper layer 13 is formed, and the light shielding layer 14 is formed.

When a protective layer, a light-shielding layer, a chemical-resistant layer, an antireflection layer, and the like are laminated in addition to the phase shift layer 12, the etching stopper layer 13, and the light-shielding layer 14, the method for manufacturing a mask blank may have a lamination step of these layers.

As an example, an adhesion layer containing chromium may be mentioned.

Fig. 3 is a sectional view showing a manufacturing process of the phase shift mask in the present embodiment. Fig. 4 is a sectional view showing a manufacturing process of the phase shift mask in the present embodiment. Fig. 5 is a sectional view showing a manufacturing process of the phase shift mask in the present embodiment. Fig. 6 is a sectional view showing a manufacturing process of the phase shift mask in the present embodiment. Fig. 7 is a sectional view showing a manufacturing process of the phase shift mask in the present embodiment. Fig. 8 is a sectional view showing a manufacturing process of the phase shift mask in the present embodiment. Fig. 9 is a sectional view showing a manufacturing process of the phase shift mask in the present embodiment. Fig. 10 is a cross-sectional view showing a phase shift mask in the present embodiment.

As shown in fig. 10, a phase shift mask (photomask) 10 in the present embodiment is obtained by patterning a phase shift layer 12, an etching stopper layer 13, and a light shielding layer 14 laminated as a mask blank 10B.

Next, a method for manufacturing the phase shift mask 10 from the mask blank 10B of the present embodiment will be described.

As a resist pattern forming step, as shown in fig. 2, a photoresist layer 15 is formed on the outermost surface of the mask blank 10B. Alternatively, mask blank 10B having photoresist layer 15 formed on the outermost surface may be prepared in advance. The photoresist layer 15 may be either a positive type or a negative type. As a material of the photoresist layer 15, a material that can cope with etching of a chromium-based material and etching of a molybdenum silicide-based material can be used. As the photoresist layer 15, a liquid resist can be used.

Next, the photoresist layer 15 is exposed and developed, whereby a resist pattern 15P1 is formed on the outer side of the light-shielding layer 14. The resist pattern 15P1 functions as an etching mask used for etching the phase shift layer 12, the etching stopper layer 13, and the light-shielding layer 14.

The shape of the resist pattern 15P1 is appropriately determined according to the etching patterns of the phase shift layer 12, the etching stopper layer 13, and the light-shielding layer 14. For example, the shape is set to have an opening width corresponding to the opening width dimension of the formed light-transmitting region 10L (see fig. 6 to 10).

Next, as a light-shielding pattern forming step, the light-shielding layer 14 is wet-etched with an etching solution through the resist pattern 15P1, thereby forming a light-shielding pattern 14P1 as shown in fig. 3.

As the etching solution for the chromium-based material, an etching solution containing cerium ammonium nitrate can be used in the light-shielding pattern forming step. For example, cerium ammonium nitrate containing acids such as nitric acid and perchloric acid is preferably used.

In the light-shielding pattern forming step, the etching stopper layer 13 made of molybdenum silicide is hardly etched by the above-described chromium-based etching liquid.

In this case, since the peak region 13A is provided in the etching stopper layer 13, the etching resistance to the chromium-based etching solution can be improved. Meanwhile, since the peak region 13A is provided in the etching stopper layer 13, adhesion between the light shielding layer 14 and the etching stopper layer 13 can be improved, and the etched shape can be prevented from collapsing.

Next, as an etching stop pattern forming step, the etching stop layer 13 is wet-etched with an etching solution through the light-shielding pattern 14P1, thereby forming an etching stop pattern 13P1 as shown in fig. 4.

As the etching solution in the etching stop pattern forming step, an etching solution capable of etching the etching stop layer 13 made of molybdenum silicide can be used. As such an etching solution, an etching solution containing at least one fluorine compound selected from hydrofluoric acid, silicofluoric acid and ammonium bifluoride and at least one oxidizing agent selected from hydrogen peroxide, nitric acid and sulfuric acid is preferably used.

At this time, the etching rate of the molybdenum silicide-based etching liquid is reduced (E.R.) because the peak region 13A is provided in the etching stopper layer 13, but the etching time can be prevented from increasing because the film thickness of the peak region 13A is set to be small. Further, since the nitrogen concentration in the etching stopper layer 13 is set to be low at a position lower than the peak region 13A, that is, at a position close to the phase shift layer 12, the etching rate of the molybdenum silicide-based etchant is increased (E.R.), and the etching time can be shortened.

This can shorten the etching time and suppress the influence on the glass substrate 11 affected by the etching liquid.

Next, as a phase shift pattern forming step, the phase shift layer 12 is wet-etched through the patterned etching stopper pattern 13P1, light shielding pattern 14P1, and resist pattern 15P 1. Thereby, as shown in fig. 5, a phase shift pattern 12P1 is formed.

This allows the light-transmitting region 10L to be exposed on the surface of the glass substrate 11.

As the etching solution in the phase shift pattern forming step, an etching solution containing cerium ammonium nitrate can be used as in the light shielding pattern forming step. For example, cerium ammonium nitrate containing acids such as nitric acid and perchloric acid is preferably used.

For example, the molybdenum silicide compound constituting the etching stopper layer 13 can be etched by a mixed solution of ammonium bifluoride and hydrogen peroxide. In contrast, for example, the chromium compound forming the light-shielding layer 14 and the phase shift layer 12 can be etched by a mixed solution of ammonium cerium nitrate and perchloric acid.

Therefore, the selection ratio at the time of etching of each wafer becomes very large. Therefore, after the light shielding pattern 14P1, the etching stopper pattern 13P1, and the phase shift pattern 12P1 are formed by etching, as the sectional shape of the phase shift mask 10, a good sectional shape close to the vertical can be obtained.

In the phase shift pattern forming step, the etching rate is reduced by setting the oxygen concentration of the light-shielding layer 14 to be higher than the oxygen concentration of the phase shift layer 12. Therefore, the progress of the etching of the light shielding pattern 14P1 is delayed compared to the etching of the phase shift layer 12.

According to these circumstances, the angle (taper angle) θ formed by the wall surfaces formed by the etching of the light-shielding pattern 14P1, the etching stopper pattern 13P1, and the phase shift pattern 12P1 and the surface of the glass substrate 11 is close to a right angle, and may be, for example, about 90 °.

Further, the peak region 13A is formed in the etching stopper pattern 13P1 so as to be in contact with the light shielding pattern 14P1, whereby the adhesion between the light shielding pattern 14P1 and the etching stopper pattern 13P1 is improved. Thus, in the phase shift pattern forming step, the etching liquid does not enter the interface between the light shielding pattern 14P1 and the etching stopper pattern 13P 1. Therefore, a reliable pattern can be formed.

In this embodiment, as a resist pattern forming step, as shown in fig. 6, the resist layer 15 is exposed and developed, thereby forming a resist pattern 15P2 on the outer side of the light-shielding pattern 14P 1. The resist pattern 15P2 functions as an etching mask for the etching stopper pattern 13P1 and the light shielding pattern 14P 1.

The shape of the resist pattern 15P2 is appropriately determined according to the etching patterns of the etching stop pattern 13P1 and the light shielding pattern 14P 1. For example, the phase shift region 10P2 and the exposure region 10P1 (see fig. 8 to 10) are formed to have an opening width corresponding to the opening width.

Next, as a light-shielding pattern patterning step, the light-shielding pattern 14P1 is wet-etched with an etching solution through the resist pattern 15P2, thereby forming a light-shielding pattern 14P2 as shown in fig. 7.

As the etching solution in the pattern forming step for the light-shielding pattern, an etching solution containing cerium ammonium nitrate can be used as well as the etching solution for the chromium-based material. For example, cerium ammonium nitrate containing acids such as nitric acid and perchloric acid is preferably used.

In the light-shielding pattern patterning step, the etching stopper pattern 13P1 made of molybdenum silicide was hardly etched by the above-described chromium-based etching solution.

At this time, since the peak region 13A is provided in the etching stopper pattern 13P1, the etching resistance to the chromium-based etching solution can be improved. Meanwhile, since the peak region 13A is provided in the etching stopper pattern 13P1, the adhesion of the light shielding pattern 14P2 to the etching stopper pattern 13P1 can be improved, and the etched shape can be prevented from collapsing.

Next, as an etching stop pattern forming step, the etching stop pattern 13P1 is wet-etched with an etching solution through the light shielding pattern 14P 2. Then, as shown in fig. 8, the etching stopper pattern 13P2 is formed.

Thereby, the etching stopper pattern 13P2 in which the surface of the phase shift pattern 12P1 is exposed can be formed corresponding to the exposure region 10P 1.

As the etching solution in the etching stopper pattern forming step, an etching solution capable of etching the etching stopper pattern 13P1 made of molybdenum silicide can be similarly used. As such an etching solution, an etching solution containing at least one fluorine compound selected from hydrofluoric acid, silicofluoric acid and ammonium bifluoride and at least one oxidizing agent selected from hydrogen peroxide, nitric acid and sulfuric acid is preferably used.

At this time, since the peak region 13A is provided in the etching stopper pattern 13P1, the etching rate of the molybdenum silicide-based etching liquid is reduced (E.R.). On the other hand, since the film thickness of the peak region 13A is set to be small, the etching time for forming the etching stopper pattern 13P2 can be prevented from becoming long. Further, the nitrogen concentration in the etching stopper pattern 13P1 at a position lower than the peak region 13A, that is, closer to the phase shift pattern 12P1 is set to be low. Therefore, the etching rate of the molybdenum silicide-based etching solution (E.R.) is increased, and the etching time for forming the etching stopper pattern 13P2 can be shortened.

This can shorten the etching time and suppress the influence of the etching liquid on the glass substrate 11 exposed in the light-transmitting region 10L and other regions.

Next, as a phase shift pattern forming step, the phase shift pattern 12P1 was wet-etched with an etching solution through the resist pattern 15P2, the light-shielding pattern 14P2, and the etching stopper pattern 13P 2. Thereby, as shown in fig. 9, a phase shift pattern 12P2 is formed.

As the etching solution in the phase shift pattern forming step, an etching solution containing cerium ammonium nitrate can be used as in the light-shielding pattern forming step. For example, cerium ammonium nitrate containing acids such as nitric acid and perchloric acid is preferably used.

At this time, the exposed surface of the light-shielding pattern 14P2 is wet-etched simultaneously with the wet etching of the phase-shift pattern 12P 1. Wet etching of the exposed surface of the light-shielding pattern 14P2 is performed in the lateral direction in the drawing, and as shown in fig. 9, the light-shielding pattern 14P3 larger than the opening width of the phase-shift pattern 12P2 is formed.

The molybdenum silicide compound constituting the etching stopper layer 13 and the chromium compound forming the light-shielding layer 14 and the phase shift layer 12 each have a very large selection ratio during wet etching. Therefore, the etching of the phase shift pattern 12P1 covered with the etch stop layer 13 is not performed. On the other hand, the light-shielding pattern 14P2 with the exposed pattern cross section and the phase shift pattern 12P1 in the region where the etching stopper layer 13 was removed were etched.

Here, the light-shielding pattern 14P2 is etched in a direction along the surface of the glass substrate 11, and the phase shift pattern 12P1 in the region where the etching stopper layer 13 is removed is etched in the thickness direction.

Thereby, a pattern having the phase shift pattern 12P2 protruding toward the exposure region 10P1 more than the light shielding pattern 14P3 and having the phase shift region 10P2, which is required for the sectional shape of the phase shift mask 10, can be formed.

In this case, as the cross-sectional shape of the phase shift mask 10, a good cross-sectional shape close to the vertical can be obtained.

In the phase shift pattern forming step, the etching rate is reduced by setting the oxygen concentration of the light-shielding layer 14 to be higher than the oxygen concentration of the phase shift layer 12. Therefore, for the etching of the phase shift pattern 12P1, the progress of etching of the light shielding pattern 14P2 is set to a prescribed state, and the width dimension of the phase shift region 10P2 is set.

According to these circumstances, in the light-shielding pattern 14P3, the etching stopper layer 13P2, and the phase shift pattern 12P2, the angle (taper angle) θ formed by the wall surfaces formed by the respective etches and the surface of the glass substrate 11 is close to a right angle, and may be, for example, about 90 °.

Further, the peak region 13A is formed in the etching stopper pattern 13P1 so as to be in contact with the light shielding pattern 14P2, whereby the adhesion between the light shielding pattern 14P2 and the etching stopper pattern 13P2 is improved. Thus, in the phase shift pattern forming step, the etching liquid does not enter the interface between the light shielding pattern 14P2 and the etching stopper pattern 13P 1. Therefore, a reliable pattern can be formed.

Next, as a resist removal step, the resist pattern 15P2 is removed, and as shown in fig. 10, the phase shift mask 10 is manufactured.

Next, a method for manufacturing a mask blank according to the present embodiment will be described with reference to the drawings.

Fig. 11 is a schematic view showing an apparatus for manufacturing a mask blank according to the present embodiment.

The mask blank 10B in the present embodiment is manufactured by the manufacturing apparatus shown in fig. 11.

The manufacturing apparatus S10 shown in fig. 11 is a reciprocating (インターバック type) sputtering apparatus. The manufacturing apparatus S10 includes a loading chamber S11, an unloading chamber S16, and a film forming chamber (vacuum processing chamber) S12. The film forming chamber S12 is located between the loading chamber S11 and the unloading chamber S16. The film forming chamber S12 is connected to the loading chamber S11 by a sealing mechanism S17, and is connected to the unloading chamber S16 by a sealing mechanism S18.

The loading chamber S11 is provided with a transfer mechanism S11a for transferring the glass substrate 11, which is carried into the manufacturing apparatus S10 from the outside to the inside, to the film forming chamber S12, and an exhaust mechanism S11f such as a rotary pump for roughly evacuating the inside of the loading chamber S11.

The unloading chamber S16 is provided with a conveying mechanism S16a for conveying the glass substrate 11 on which film formation has been completed from the film forming chamber S12 to the outside of the manufacturing apparatus S10, and an exhaust mechanism S16f such as a rotary pump for roughly evacuating the inside of the unloading chamber S16.

The film forming chamber S12 is provided with a substrate holding mechanism S12a and three-stage film forming mechanisms S13, S14, and S15 as mechanisms for dealing with three film forming processes.

The substrate holding mechanism S12a holds the glass substrate 11 conveyed by the conveying mechanism S11a so that the glass substrate 11 faces the targets S13b, S14b, and S15b during film formation. The substrate holding mechanism S12a can carry in the glass substrate 11 from the loading chamber S11 and can carry out the glass substrate 11 to the unloading chamber S16.

Among the three-stage film forming mechanisms S13, S14, and S15 of the film forming chamber S12, the film forming mechanism S13 for supplying the film forming material in the first stage is provided at a position closest to the loading chamber S11.

The film forming mechanism S13 includes: a cathode electrode (backing plate) S13c with target S13 b; and a power source S13d for applying a negative potential sputtering voltage to the back plate S13 c.

The film forming mechanism S13 includes: a gas introduction mechanism S13e for intensively introducing a gas into the vicinity of the cathode electrode (backing plate) S13c in the film forming chamber S12; and a high vacuum exhaust mechanism S13f such as a turbo molecular pump for evacuating the vicinity of the cathode electrode (backing plate) S13c in the film forming chamber S12.

Further, a film forming mechanism S14 is provided at an intermediate position between the loading chamber S11 and the unloading chamber S16 in the film forming chamber S12, and the film forming mechanism S14 is configured to supply a film forming material to the second stage of the three stages of the film forming mechanisms S13, S14, and S15.

The film forming mechanism S14 includes: a cathode electrode (backing plate) S14c with a target S14 b; and a power supply S14d for applying a negative potential sputtering voltage to the backing plate S14 c.

The film forming mechanism S14 includes: a gas introduction mechanism S14e for intensively introducing a gas into the vicinity of the cathode electrode (backing plate) S14c in the film forming chamber S12; and a high vacuum exhaust mechanism S14f such as a turbo molecular pump for evacuating the vicinity of the cathode electrode (backing plate) S14c in the film forming chamber S12.

Further, among the three-stage film forming mechanisms S13, S14, and S15 of the film forming chamber S12, the film forming mechanism S15 is provided at a position closest to the unloading chamber S16, and the film forming mechanism S15 is used to supply the film forming material of the third-stage film forming mechanism.

The film forming mechanism S15 includes: a cathode electrode (backing plate) S15c with target S15 b; and a power source S15d for applying a negative potential sputtering voltage to the back plate S15 c.

The film forming mechanism S15 includes: a gas introduction mechanism S15e for intensively introducing a gas into the vicinity of the cathode electrode (backing plate) S15c in the film forming chamber S12; and a high vacuum exhaust mechanism S15f such as a turbo molecular pump for evacuating the vicinity of the cathode electrode (backing plate) S15c in the film forming chamber S12.

In the film forming chamber S12, gas barriers S12g for suppressing the flow of gas are provided near the cathode electrodes (back plates) S13c, S14c, and S15c, respectively, so that the gas supplied from the gas introduction means S13e, S14e, and S15e does not mix into the adjacent film forming means S13, S14, and S15. These gas barriers S12g are configured such that the substrate holding mechanism S12a is movable between the respectively adjacent film forming mechanisms S13, S14, S15.

In the film forming chamber S12, each of the three-stage film forming mechanisms S13, S14, and S15 has a composition required for sequentially forming films on the glass substrate 11, and can form films under conditions required for film formation.

In the present embodiment, the film formation mechanism S13 is used for forming the phase shift layer 12. The film formation mechanism S14 is used to form the etching stopper layer 13. The film forming means S15 is used for forming the light shielding layer 14.

Specifically, in the film formation mechanism S13, the target S13b is formed of a material having chromium, which is a composition required for forming the phase shift layer 12 on the glass substrate 11.

In the film forming means S13, the process gas as the gas supplied from the gas introducing means S13e contains carbon, nitrogen, oxygen, and the like, and is set to a predetermined partial pressure of gas together with the sputtering gas such as argon or nitrogen, in accordance with the formation of the phase shift layer 12.

Further, the high vacuum exhaust mechanism S13f is evacuated according to the film formation conditions.

In the film formation mechanism S13, the sputtering voltage applied from the power source S13d to the back plate S13c is set in accordance with the film formation of the phase shift layer 12.

In the film formation mechanism S14, the target S14b is formed of a material containing molybdenum silicide, which is a composition necessary for forming the etching stopper layer 13 on the phase shift layer 12.

At the same time, in the film forming means S14, the process gas as the gas supplied from the gas introducing means S14e contains carbon, nitrogen, oxygen, and the like in accordance with the formation of the etching stopper layer 13, and is set to a predetermined partial pressure together with the sputtering gas such as argon, inert gas, and the like.

The gas supplied by the gas introduction mechanism S14e is configured to be capable of adjusting the partial pressure of the nitrogen-containing gas or the like so that the amount of change is a predetermined amount according to the film thickness of the etching stopper layer 13 to be formed.

Further, the high vacuum exhaust mechanism S14f exhausts the film depending on the film forming conditions.

In the film formation mechanism S14, the sputtering voltage applied from the power source S14d to the backing plate S14c is set in accordance with the film formation of the etching stopper layer 13.

In the film forming means S15, the target S15b is formed of a material containing chromium, which is a composition necessary for forming the light shielding layer 14 on the etching stopper layer 13.

In the film forming means S15, the process gas as the gas supplied from the gas introducing means S15e contains carbon, nitrogen, oxygen, and the like in accordance with the formation of the light shielding layer 14, and is set to a predetermined partial pressure of gas together with the sputtering gas such as argon, nitrogen, and the like as the inert gas.

Further, the high vacuum exhaust mechanism S15f exhausts the film depending on the film forming conditions.

In the film forming mechanism S15, the sputtering voltage applied from the power source S15d to the back plate S15c is set in accordance with the formation of the light-shielding layer 14.

In the manufacturing apparatus S10 shown in fig. 11, three-stage sputtering film formation is performed while the glass substrate 11 carried in from the loading chamber S11 by the carrying mechanism S11a is carried in the film forming chamber S12 by the substrate holding mechanism S12 a. Then, the glass substrate 11 on which the film formation has been completed is carried out from the unloading chamber S16 to the outside of the manufacturing apparatus S10 by the carrying mechanism S16 a.

In the phase shift layer forming step, in the film forming mechanism S13, a sputtering gas and a reactive gas are supplied as supply gases from the gas introducing mechanism S13e to the vicinity of the back plate S13c of the film forming chamber S12. In this state, a sputtering voltage is applied from an external power supply to the backing plate (cathode electrode) S13 c. Further, a predetermined magnetic field may be formed on the target S13b by a magnetron magnetic circuit.

Ions of the sputtering gas are excited by the plasma in the vicinity of the back plate S13c in the film forming chamber S12, and collide with the target S13b of the cathode electrode S13c to fly particles of the film forming material. Then, the ejected particles are bonded to the reaction gas and then adhere to the glass substrate 11, so that the phase shift layer 12 is formed on the surface of the glass substrate 11 with a predetermined composition.

Similarly, in the etching stopper layer forming step, in the film forming mechanism S14, a sputtering gas and a reaction gas are supplied as supply gases from the gas introduction mechanism S14e to the vicinity of the back plate S14c of the film forming chamber S12. In this state, a sputtering voltage is applied from an external power supply to the backing plate (cathode electrode) S14 c. Further, a predetermined magnetic field may be formed in the target S14b by a magnetron magnetic circuit.

Ions of the sputtering gas are excited by the plasma in the vicinity of the backing plate S14c in the film forming chamber S12, and collide with the target S14b of the cathode electrode S14c to fly particles of the film forming material. The ejected particles are bonded to the reaction gas, and then adhere to the glass substrate 11, so that the etching stopper layer 13 is formed on the phase shift layer 12 with a predetermined composition on the surface of the glass substrate 11.

Similarly, in the light shielding layer forming step, in the film forming means S15, a sputtering gas and a reaction gas are supplied as supply gases from the gas introducing means S15e to the vicinity of the back plate S15c of the film forming chamber S12. In this state, a sputtering voltage is applied from an external power supply to the backing plate (cathode electrode) S15 c. Further, a predetermined magnetic field may be formed on the target S15b by a magnetron magnetic circuit.

Ions of the sputtering gas are excited by the plasma in the vicinity of the back plate S15c in the film forming chamber S12, and the ions collide with the target S15b of the cathode electrode S15c to fly particles of the film forming material. The ejected particles are bonded to the reaction gas and then adhere to the glass substrate 11, and the light shielding layer 14 is formed on the surface of the glass substrate 11 by laminating the particles on the etching stopper layer 13 with a predetermined composition.

At this time, during the deposition of the phase shift layer 12, a sputtering gas, an oxygen-containing gas, and the like are supplied from the gas introduction mechanism S13e so as to have a predetermined partial pressure, and the partial pressure is controlled to be switched so that the composition of the phase shift layer 12 is set within a predetermined range. Meanwhile, when the composition is changed in the film thickness direction to form the phase shift layer 12, the respective gas partial pressures in the atmosphere gas may also be changed according to the film thickness of the film to be formed.

During the deposition of the etching stopper layer 13, a sputtering gas, a nitrogen-containing gas, and the like are supplied from the gas introduction mechanism S14e at a predetermined partial pressure, and the partial pressure of the nitrogen-containing gas is controlled to be switched. Thereby, the composition of the etching stopper layer 13 is set to a predetermined concentration ratio or a fluctuating concentration.

In particular, as described above, the partial pressure ratio of the nitrogen-containing gas is controlled so that the peak region 13A having a high nitrogen concentration and the other region having a nitrogen concentration lower than that of the peak region 13A are formed in the film thickness direction.

Specifically, when the molybdenum silicide compound film is formed, the peak region 13A can be formed by increasing the partial pressure of nitrogen gas from the time when the film is formed to a predetermined film thickness such as 2/3, which is the film thickness of the etching stopper layer 13, with an increase in the film thickness.

Meanwhile, in order to set the etching stop capability of the etching stop layer 13 to a predetermined state, the composition ratio of molybdenum to silicon and the composition ratio of the content other than molybdenum to silicon in the target S14b may be set to a predetermined state. In addition, it is preferable to appropriately select the targets S14b having different composition ratios.

During the formation of the light-shielding layer 14, nitrogen gas, oxygen-containing gas, or the like having a predetermined partial pressure is supplied from the gas introduction means S15e, and the partial pressure is controlled to be switched so that the composition of the light-shielding layer 14 is within a predetermined range.

Here, the oxygen-containing gas may be CO₂(carbon dioxide), O₂(oxygen), N₂O (nitrous oxide), NO (nitric oxide), CO (carbon monoxide), and the like.

In addition, as the carbon-containing gas, CO can be cited₂(carbon dioxide), CH₄(methane), C₂H₆(ethane), CO (carbon monoxide), and the like.

Further, as the nitrogen-containing gas, N may be mentioned₂(Nitrogen), N₂O (nitrous oxide), NO (nitric oxide), NH₃(ammonia), and the like.

In the formation of the phase shift layer 12, the etching stopper layer 13, and the light shielding layer 14, the targets S13b, S14b, and S15b may be replaced if necessary.

In addition to the formation of the phase shift layer 12, the etching stopper layer 13, and the light shielding layer 14, other films may be laminated on the glass substrate 11. In this case, the following methods can be cited: this method uses a target corresponding to the material of the film laminated above the glass substrate 11, and sets sputtering conditions of gas and the like to form a film by sputtering. Alternatively, the mask blank 10B of the present embodiment may be obtained by laminating films by a film formation method other than sputtering.

Next, film characteristics of the phase shift layer 12, the etching stopper layer 13, and the light shielding layer 14, particularly film characteristics of the etching stopper layer in the present embodiment will be described.

On the glass substrate 11 for forming a mask, a phase shift layer 12 constituting a chromium compound film is formed by sputtering or the like. The chromium compound film formed here is preferably a film containing chromium, oxygen, nitrogen, carbon, and the like. By controlling the composition and thickness of chromium, oxygen, nitrogen, and carbon contained in the film at this time, the phase shift layer 12 having a desired transmittance and phase can be formed.

Next, a molybdenum silicide film to be the etching stopper layer 13 is formed by sputtering or the like. The molybdenum silicide compound film formed here is preferably a film containing molybdenum, silicon, oxygen, nitrogen, carbon, or the like.

Then, a chromium compound film to be the light-shielding layer 14 is formed by sputtering or the like. The chromium compound film formed here is preferably a film containing chromium, oxygen, nitrogen, carbon, and the like.

By forming the mask blank 10B having such a film structure, the phase shift mask 10 in which the phase shift layer 12 and the light-shielding layer 14 are formed of a chromium compound can be formed.

When the etching stopper layer 13 is formed using a molybdenum silicide film, it is necessary to perform etching using an etching solution containing hydrofluoric acid. Therefore, it is necessary to reduce the influence of etching on the glass substrate 11. Therefore, it is preferable to accelerate the etching rate (E.R.) in the molybdenum silicide film as much as possible and use it.

Fig. 12 shows the relationship between the nitrogen concentration in the film and the etching rate when the molybdenum silicide film is formed using molybdenum silicide targets different in target composition. As is clear from fig. 12, by using a molybdenum silicide target having a small silicon composition as the target composition, a molybdenum silicide film having a high etching rate can be formed.

Further, with respect to the molybdenum silicide target, by mixing MoSi as a crystal of molybdenum silicide₂And Si, thereby enabling formation of a target of a desired composition ratio.

Here, if the silicon ratio is not more than constant, MoSi is not preferable₂If the amount of the precursor is too large, it is difficult to form a target having a stable composition.

In contrast, the present inventors have found that a target having a high relative density can be stably formed if the silicon composition is increased until the composition ratio of molybdenum to silicon is 1: 2.3. Therefore, by using a target having a composition ratio of molybdenum silicide of 1:2.3, a high-density target can be used in a state in which etching of the glass substrate 11 is suppressed.

Thereby, the mask blank 10B suitable for the phase shift mask 10 with reduced influence of production defects can be manufactured as a product.

These manufacturing conditions and film characteristics in the etching stopper layer 13 were verified.

First, a molybdenum silicide film was formed as the etching stopper 13 using a target having a composition ratio of molybdenum to silicon of 1:2.3, and the molybdenum silicide film was formed by changing the flow rates of argon and nitrogen during film formation.

In the manufacturing process of the phase shift mask 10, chemical liquids such as acids and bases are generally used, but it is necessary to suppress the transmittance change during the process.

The inventors have found that by increasing the nitrogen concentration of the molybdenum silicide film, the chemical liquid resistance to acids and bases is increased.

Thus, as mask blank 10B, peak region 13A formed of a molybdenum silicide film having a high nitrogen concentration is formed at the interface between light-shielding layer 14 and etching stopper layer 13. As the mask blank 10B, a molybdenum silicide film having a low nitrogen concentration is used in a portion of the etching stopper layer 13 below the peak region 13A (a portion close to the glass substrate 11).

This can shorten the etching time of the etching stopper film and reduce the influence of the contact between the glass substrate 11 and the etching solution, and can form the etching stopper film having high chemical liquid resistance.

Further, the present inventors have found that the etching stopper layer 13, which is formed by forming a molybdenum silicide film having a high nitrogen concentration on the surface when etching the light-shielding layer 14 as a chromium film, has a high etching stopper function with little permeation of an etching solution or the like.

Therefore, it is preferable to use a molybdenum silicide film having a high nitrogen concentration as much as possible for the etch stop layer 13.

Therefore, by forming the peak region 13A as the molybdenum silicide film having a high nitrogen concentration on the upper layer of the etching stopper layer 13, the following effects are also obtained: that is, when the light-shielding layer 14 is etched, the penetration of the etching liquid is suppressed in the vicinity of the interface between the light-shielding layer 14 and the etching stopper layer 13.

Further, the present inventors investigated the relationship between the etching rate of the molybdenum silicide film and the sheet resistance, and as a result, found that the etching rate of the molybdenum silicide film is increased if the sheet resistance becomes low.

It can be seen that the resistivity was 1.0X 10 by using^-3The molybdenum silicide film of Ω cm or less serves as an etching stopper layer, and thus an etching stopper layer having a high etching rate can be formed. Further, it was also clarified that electrostatic breakdown can be suppressed by using a molybdenum silicide film having a low resistivity.

In the case of using a molybdenum silicide film as the etching stopper 13, a target having a ratio of molybdenum to silicon of 1:3 or less is used. A nitrogen-containing gas is used as an atmospheric gas in sputtering. By controlling the gas partial pressure of the nitrogen-containing gas, a peak region 13A having a nitrogen concentration of 30% or more is formed at the interface between the light-shielding layer 14 and the etching stopper layer 13. The nitrogen concentration in the lower portion of the glass substrate 11 side with respect to the peak region 13A is set to 25% or less.

The thickness of the etching stopper layer 13 as a molybdenum silicide film is set to 10nm to 100nm, and the resistivity of the lower portion on the glass substrate 11 side of the peak region 13A is set to 1.0 × 10^-3Omega cm or less. By using such a molybdenum silicide film as the etching stopper layer 13, the phase shift mask 10 having a favorable cross-sectional shape and little influence on etching of the glass substrate 11 can be formed.

[ examples ]

Next, examples according to the present invention will be explained.

In addition, as a specific example of the etching stopper layer 13 in the present invention, a confirmation test will be described.

< example >

As example 1, a molybdenum silicide compound film was formed as an etching stopper layer on a glass substrate by a sputtering method or the like. The molybdenum silicide compound film formed here is a film containing molybdenum, silicon, oxygen, nitrogen, carbon, or the like. The film was evaluated for composition using auger electron spectroscopy.

The results are shown in FIG. 13.

As shown in fig. 13, it was confirmed that a peak region having a high nitrogen concentration was formed on the left side in the figure.

Then, in the sputtering for forming the molybdenum silicide film, a target having a ratio of molybdenum to silicon of 1:2.3 is used, and the film is formed by changing the partial pressure of nitrogen gas within a range of 0 to 100%.

The atmosphere gas used for sputtering is nitrogen, carbon dioxide, or argon.

The composition ratios, the etching rates of molybdenum and silicon, and the ratios of the etching rates to the etching rate of glass were measured as examples 1 to 4.

The results are shown in table 1.

Similarly, in the sputtering for forming a molybdenum silicide film, a target having a ratio of molybdenum to silicon of 1:3.7 is used, and the film is formed by changing the partial pressure of nitrogen gas within a range of 0 to 100%.

The atmosphere gas used for sputtering is nitrogen, carbon dioxide, or argon.

The composition ratios, the etching rates of molybdenum and silicon, and the ratios of the etching rates to the etching rate of glass were measured as examples 5 to 8.

The results are shown in table 1.

In addition, in examples 1 to 8, the relationship between the etching rate of the molybdenum silicide film and the sheet resistance was examined, respectively.

From these results, it was found that the nitrogen concentration in the molybdenum silicide film can be controlled by the nitrogen partial pressure at the time of film formation. Further, by sputtering using a mosi2.3 target having a composition ratio of Si/Mo of 2.3, a molybdenum silicide film having a low resistivity can be formed. This shows that the influence of electrostatic breakdown can be reduced.

Further, it was found that a molybdenum silicide film suitable for use in a phase shift mask can be formed by using a laminated structure of a molybdenum silicide film having a high nitrogen concentration and a molybdenum silicide film having a low nitrogen concentration, and the sectional shape of the molybdenum silicide film is good and the etching time can be shortened.

Further, it is known that the chemical liquid resistance to acid and alkali is improved by increasing the nitrogen concentration of the molybdenum silicide film. It is known that an etching stopper film using a molybdenum silicide film having a high nitrogen concentration has a high etching stopper function with little permeation of an etching solution or the like at the time of etching a chromium film. As a result of examining the relationship between the etching rate of the molybdenum silicide film and the sheet resistance, it was found that the etching rate of the molybdenum silicide film was increased if the sheet resistance was low. Further, it was also found that electrostatic breakdown can be suppressed by using a molybdenum silicide film having a low resistivity.

The present inventors have completed the present invention based on these circumstances. Thus, a mask having a good cross-sectional shape and having little influence on etching of the glass substrate can be formed

Description of the reference numerals

10 … phase shift mask

10B … mask blank

10L … light transmitting area

10P1 … exposure region

10P2 … phase shift region

11 … glass substrate (transparent substrate)

12 … phase shift layer

12P1 … phase shift pattern

13 … etch stop layer

13P1, 13P2 … etch stop pattern

14 … light-shielding layer

14P1, 14P2 … shading pattern

15 … Photoresist layer

15P1, 15P2 … resist pattern