KR20210038354A - Mask blanks and photomask - Google Patents

Abstract

The present invention relates to a mask blank having a mask layer which becomes a photo-mask with predetermined optical density at low reflectance. The mask layer comprises: a lower reflection prevention layer laminated on a transparent substrate; a light blocking layer provided at the position spaced apart from the transparent substrate rather than the lower reflection prevention layer; and an upper reflection prevention layer provided in the position spaced apart from the transparent substrate rather than the light blocking layer.

Description

Mask blanks and photomask {MASK BLANKS AND PHOTOMASK}

TECHNICAL FIELD The present invention relates to a mask blank and a photomask, and in particular, to a suitable technique for use in the manufacture of binary mask blanks having low reflection on both sides or binary mask blanks.

In the manufacture of a photomask for a large plate such as a flat panel display (FPD), a mask blank having a light-shielding layer is used as a binary mask. In addition, the need to form a fine pattern is increasing with the high precision of FPD.

In such mask blanks, a structure in which a film made of a chromium material is laminated on a transparent substrate such as glass is generally used as a mask layer including a patterned light-shielding layer or the like (Patent Document 1).

In order to create a fine pattern, it is necessary to reduce the reflectance on the front and back surfaces of the mask blank as a countermeasure against stray light during pattern formation (e.g., 5% or less reflectance in exposure light having a wavelength of 436 nm).

As the film structure of the mask blanks that realizes low reflectance on the front and back surfaces, for example, at least a three-layer structure laminated with an antireflection layer (back side), a light shielding layer, and an antireflection layer (surface) from a glass substrate is used. The branch mask layer is known.

When such an antireflection layer is provided, an oxidized chromium oxide film or the like can be used as the antireflection layer in order to obtain a film having a low refractive index.

Patent Document 1: Japanese Patent Laid-Open No. 2001-305716

However, a chromium oxide film having a high oxygen concentration has a low etching rate. As a result, when a chromium oxide film having a high oxygen concentration is employed as the antireflection layer, the etching rate of the antireflection layer is lower than that of the light-shielding layer, and thus the etching of the antireflection layer sometimes does not proceed.

For this reason, when the mask pattern is produced, the etching of the light-shielding layer proceeds compared to the antireflection layer, and the amount of side etching in the mask blank, that is, the amount of side etching, is not uniform in the thickness direction. Specifically, it has been found that there is a problem in that the central portion of the mask layer in the thickness direction is unnecessarily etched a lot, resulting in the occurrence of a cross-sectional shape formed of the eaves and hem.

In order to make the cross-sectional shape of the pattern perpendicular to the surface of the glass substrate, it is necessary to match the etching rate of each layer, but in order to maintain the optical properties of each layer, the composition ratio is greatly different, so it is inevitable that the difference in the etching rate is large. . For this reason, a mask blank capable of forming a vertical pattern cross-sectional shape has not been realized.

In addition, in pattern formation in mask blanks, in order to increase the contrast, there is a demand that it is desired to cope with an optical density higher than the conventional optical density OD3 (for example, OD5).

In order to meet this demand, it is necessary to make the difference between the oxygen concentration of the light-shielding layer and the oxygen concentration of the antireflection layer larger. For this reason, the difference in the etching rate between the light shielding layer and the antireflection layer is further increased.

For this reason, in the conventional optical density (OD3), the deviation from the vertical of the cross-sectional shape which has been allowed has become unacceptable at a high optical density (for example, OD5).

The present invention has been made in view of the above circumstances, and has a predetermined optical density at a low reflectance, and a mask capable of having an appropriate cross-sectional shape with reduced eaves and hem because the etching rate of the light-shielding layer and the anti-reflection layer can be approached. To achieve the purpose of providing blanks.

A mask blank according to one embodiment of the present invention is a mask blank having a mask layer serving as a photomask, wherein the mask layer is a lower antireflection layer laminated on a transparent substrate, and the lower antireflection layer is separated from the transparent substrate from the lower antireflection layer. It has a light-shielding layer provided at the position, and an anti-reflection layer provided at a position separated from the transparent substrate from the light-shielding layer. The lower antireflection layer is an oxynitride carbide film containing chromium, oxygen, nitrogen, and carbon, the content of chromium contained in the lower antireflection layer is 25 atm% to 50 atm%, and the oxygen contained in the lower antireflection layer The content rate is 30 atm% to 50 atm%, the nitrogen content in the lower reflection prevention layer is 10 atm% to 30 atm%, and the carbon content in the lower reflection prevention layer is 2 atm% to 5 atm% . The light-shielding layer is a nitride film containing chromium and nitrogen, the content of chromium in the light-shielding layer is 70 atm% to 95 atm%, and the content of nitrogen is 5 atm% to 20 atm%. The anti-reflection layer is an oxynitride carbide film containing chromium, oxygen, nitrogen, and carbon, the content of chromium in the anti-reflection layer is 25 atm% to 50 atm%, and the oxygen contained in the anti-reflection layer The content rate is 55 atm% to 70 atm%, the nitrogen content in the anti-reflection layer is 5 atm% to 20 atm%, and the carbon content in the anti-reflection layer is 2 atm% to 5 atm% . For this reason, the said subject was solved.

A mask blank according to one embodiment of the present invention is a mask blank having a mask layer serving as a photomask, wherein the mask layer is a lower antireflection layer laminated on a transparent substrate, and the lower antireflection layer is separated from the transparent substrate from the lower antireflection layer. It has a light-shielding layer provided at the position, and an anti-reflection layer provided at a position separated from the transparent substrate from the light-shielding layer. The lower antireflection layer is an oxynitride carbide film containing chromium, oxygen, nitrogen, and carbon, the content of chromium contained in the lower antireflection layer is 25 atm% to 50 atm%, and the oxygen contained in the lower antireflection layer The content rate is 30 atm% to 50 atm%, the nitrogen content in the lower reflection prevention layer is 10 atm% to 30 atm%, and the carbon content in the lower reflection prevention layer is 2 atm% to 5 atm% . The light-shielding layer is a nitride carbide film containing chromium, nitrogen, and carbon, the content of chromium in the light-shielding layer is 70 atm% ~ 95 atm%, and the content of nitrogen in the light-shielding layer is 5 atm% ~ It is 20 atm%, and the content of carbon contained in the light-shielding layer is 0 atm% to 15 atm%. The anti-reflection layer is an oxynitride carbide film containing chromium, oxygen, nitrogen, and carbon, the content of chromium in the anti-reflection layer is 25 atm% to 50 atm%, and the oxygen contained in the anti-reflection layer The content rate is 55 atm% to 70 atm%, the nitrogen content in the anti-reflection layer is 5 atm% to 20 atm%, and the carbon content in the anti-reflection layer is 2 atm% to 5 atm% . For this reason, the said subject was solved.

In the mask blank according to one embodiment of the present invention, the reflectance of exposure light having a wavelength of 365 nm to 436 nm on both surfaces of the mask layer may be 10% or less.

In the mask blank according to one embodiment of the present invention, both surfaces of the mask layer may have a reflectance of 5% or less in exposure light having a wavelength of 436 nm.

In the mask blank according to one embodiment of the present invention, in the mask layer, the film thickness of the lower reflection prevention layer, the film thickness of the light shielding layer, and the film thickness of the top reflection prevention layer are set so that the optical density is 3.0 or more. May be.

In the mask blanks according to one embodiment of the present invention, the film thickness of the lower reflection prevention layer is 25.0 nm to 35.0 nm, the film thickness of the light shielding layer is 125.0 nm to 135.0 nm, and the film thickness of the top reflection prevention layer is 25.0 nm. nm to 35.0 nm may be used.

In the mask blank according to one embodiment of the present invention, the thickness of the mask layer may be 175.0 nm to 205.0 nm.

In the mask blank according to one embodiment of the present invention, a photoresist layer may be provided at a position separated from the transparent substrate rather than the mask layer.

The photomask according to one aspect of the present invention is manufactured from the mask blanks according to the above aspect.

A mask blank according to one embodiment of the present invention is a mask blank having a mask layer serving as a photomask, wherein the mask layer is a lower antireflection layer laminated on a transparent substrate, and the lower antireflection layer is separated from the transparent substrate from the lower antireflection layer. It has a light-shielding layer provided at the position, and an anti-reflection layer provided at a position separated from the transparent substrate from the light-shielding layer. The lower antireflection layer is an oxynitride carbide film containing chromium, oxygen, nitrogen, and carbon, the content of chromium contained in the lower antireflection layer is 25 atm% to 50 atm%, and the oxygen contained in the lower antireflection layer The content rate is 30 atm% to 50 atm%, the nitrogen content in the lower reflection prevention layer is 10 atm% to 30 atm%, and the carbon content in the lower reflection prevention layer is 2 atm% to 5 atm% . The light-shielding layer is a nitride film containing chromium and nitrogen, the content of chromium in the light-shielding layer is 70 atm% to 95 atm%, and the content of nitrogen is 5 atm% to 20 atm%. The anti-reflection layer is an oxynitride carbide film containing chromium, oxygen, nitrogen, and carbon, and the content of chromium contained in the anti-reflection layer is 25 atm% to 50 atm%, more preferably 30 atm% to 50 atm%, the content of oxygen in the anti-reflection layer is 55 atm% to 70 atm%, the content of nitrogen in the anti-reflection layer is 5 atm% to 20 atm%, and included in the anti-reflection layer The content of carbon is 2 atm% to 5 atm%. For this reason, the said subject was solved.

For this reason, it is possible to put the cross-sectional shape for patterning into an appropriate range while maintaining the low reflectance on both sides of the mask layer and the required optical density. Specifically, with respect to the upper and lower antireflection layers, the side etching of the light-shielding layer is in a predetermined range, so that the portion of the light-shielding layer is not dent.

Accordingly, when manufacturing a photomask, the cross-sectional shape of the mask blanks when patterning (resist coating, exposure, development, and etching) is performed can be made as vertical as possible. By setting the dimensions of the pattern affected by the cross-sectional shape of the pattern to a predetermined range, it is possible to realize a high-precision photomask.

A mask blank according to one embodiment of the present invention is a mask blank having a mask layer serving as a photomask, wherein the mask layer is a lower antireflection layer laminated on a transparent substrate, and the lower antireflection layer is separated from the transparent substrate from the lower antireflection layer. It has a light-shielding layer provided at the position, and an anti-reflection layer provided at a position separated from the transparent substrate from the light-shielding layer. The lower antireflection layer is an oxynitride carbide film containing chromium, oxygen, nitrogen, and carbon, the content of chromium contained in the lower antireflection layer is 25 atm% to 50 atm%, and the oxygen contained in the lower antireflection layer The content rate is 30 atm% to 50 atm%, the nitrogen content in the lower reflection prevention layer is 10 atm% to 30 atm%, and the carbon content in the lower reflection prevention layer is 2 atm% to 5 atm% . The light-shielding layer is a nitride carbide film containing chromium, nitrogen, and carbon, the content of chromium in the light-shielding layer is 70 atm% ~ 95 atm%, and the content of nitrogen in the light-shielding layer is 5 atm% ~ It is 20 atm%, and the content of carbon contained in the light-shielding layer is 0 atm% to 15 atm%. The anti-reflection layer is an oxynitride carbide film containing chromium, oxygen, nitrogen, and carbon, and the content of chromium contained in the anti-reflection layer is 25 atm% to 50 atm%, more preferably 30 atm% to 50 atm%, the content of oxygen in the anti-reflection layer is 55 atm% to 70 atm%, the content of nitrogen in the anti-reflection layer is 5 atm% to 20 atm%, and included in the anti-reflection layer The content of carbon is 2 atm% to 5 atm%. For this reason, the said subject was solved.

For this reason, it is possible to put the cross-sectional shape for patterning into an appropriate range while maintaining the low reflectance on both sides of the mask layer and the required optical density. Specifically, with respect to the upper and lower antireflection layers, the side etching of the light-shielding layer is in a predetermined range, so that the portion of the light-shielding layer is not dent.

Accordingly, when manufacturing a photomask, the cross-sectional shape of the mask blanks when patterning (resist coating, exposure, development, and etching) is performed can be made as vertical as possible. The dimensions of the pattern affected by the cross-sectional shape of this pattern can be set to a predetermined range, and a high-precision photomask can be realized.

In the mask blank according to one embodiment of the present invention, on both sides of the mask layer, reflectance in exposure light having a wavelength of 365 nm to 436 nm may be 10% or less, and in particular, reflectance in exposure light having a wavelength of 436 nm. All of these may be 5% or less.

For this reason, by setting the composition ratio of each layer to the above-described range, it is possible to realize a range of low reflectance required for patterning while enabling a desirable cross-sectional shape to be realized.

Moreover, as said reflectance, the transparent substrate side is the reflectance containing this transparent substrate.

In the mask blank according to one embodiment of the present invention, in the mask layer, the film thickness of the lower reflection prevention layer, the film thickness of the light shielding layer, and the film thickness of the top reflection prevention layer are set so that the optical density is 3.0 or more. May be.

For this reason, by setting the composition ratio of each layer to the above-described range, it is possible to realize a range of optical density required for patterning while enabling a desirable cross-sectional shape to be realized.

In the mask blanks according to one embodiment of the present invention, the film thickness of the lower reflection prevention layer is 25.0 nm to 35.0 nm, the film thickness of the light shielding layer is 125.0 nm to 135.0 nm, and the film thickness of the top reflection prevention layer is 25.0 nm. nm to 35.0 nm.

For this reason, by setting the composition ratio of each layer to the above-described range, it is possible to realize a range of optical density required for patterning while enabling a desirable cross-sectional shape to be realized.

In the mask blank according to one embodiment of the present invention, the thickness of the mask layer may be 175.0 nm to 205.0 nm.

For this reason, by making the composition ratio of each layer into the above-described range, it is possible to realize a desirable cross-sectional shape, while realizing a range of optical density required for patterning and a range of low reflectance required for patterning.

In the mask blank according to one embodiment of the present invention, it is possible to have a photoresist layer provided at a position separated from the transparent substrate rather than the mask layer.

The photomask according to one embodiment of the present invention can be manufactured from the mask blanks described in any one of the above.

According to the present invention, it is possible to provide a mask blank that has a predetermined optical density at a low reflectivity, so that the etching rate of the light-shielding layer and the anti-reflection layer can be approached, thereby reducing the eaves and hem. It becomes possible to pay.

1 is a cross-sectional view showing a mask blank according to a first embodiment of the present invention.
2 is a cross-sectional view showing a mask blank according to a first embodiment of the present invention.
3 is a cross-sectional view showing a photomask according to the first embodiment of the present invention.
4 is a schematic diagram showing a film forming apparatus in a method for manufacturing a mask blank and a photomask according to the first embodiment of the present invention.
5 is a graph showing surface spectral reflectance in Examples and Comparative Examples of mask blanks according to the present invention.
6 is a graph showing the spectral reflectance of the back side in Examples and Comparative Examples of the mask blanks according to the present invention.
7 is a SEM photograph showing a cross-sectional shape after patterning in Example 1 of a mask blank according to the present invention.
8 is a SEM photograph showing a cross-sectional shape after patterning in Example 2 of a mask blank according to the present invention.
9 is a SEM photograph showing a cross-sectional shape after patterning in Comparative Example 1 of a mask blank according to the present invention.
10 is a SEM photograph showing a cross-sectional shape after patterning in Comparative Example 2 of a mask blank according to the present invention.
11 is an SEM photograph showing a cross-sectional shape after patterning in Comparative Example 3 of a mask blank according to the present invention.
12 is a bird's-eye SEM photograph showing the shape of the mask blanks according to the present invention after patterning in Experimental Example 1. FIG.
13 is a bird's-eye SEM photograph showing the shape of the mask blanks according to the present invention after patterning in Experimental Example 2;
14 is a bird's-eye SEM photograph showing a shape after patterning in Comparative Example 1 of a mask blank according to the present invention.
15 is a bird's-eye SEM photograph showing a shape after patterning in Comparative Example 2 of a mask blank according to the present invention.
16 is a bird's-eye SEM photograph showing a shape after patterning in Comparative Example 3 of a mask blank according to the present invention.

Hereinafter, a mask blank, a photomask, a method for manufacturing a mask blank, and a method for manufacturing a photomask according to the first embodiment of the present invention will be described based on the drawings.

Fig. 1 is a cross-sectional view showing a mask blank in this embodiment, Fig. 2 is a cross-sectional view showing the mask blank in this embodiment, and in the drawing, reference numeral 10B denotes a mask blank.

The mask blank 10B according to the present embodiment is provided in a binary mask (photomask) used in a range of about 365 nm to 436 nm in wavelength of exposure light.

As shown in FIG. 1, the mask blank 10B according to this embodiment includes a glass substrate (transparent substrate) 11, a lower antireflection layer 12 formed on the glass substrate 11, and a lower reflection. It consists of a light blocking layer 13 formed on the blocking layer 12 and an anti-reflection layer 14 formed on the blocking layer 13.

That is, the light-shielding layer 13 is provided at a position separated from the glass substrate 11 from the lower reflection prevention layer 12. Further, the anti-reflection layer 14 is provided at a position separated from the glass substrate 11 from the light shielding layer 13.

These lower anti-reflection layer 12, light shielding layer 13, and upper anti-reflection layer 14 constitute a mask layer which is a low-reflective lamination film having optical properties required as a photomask.

In addition, as shown in FIG. 1, the mask blank 10B according to the present embodiment is a layered mask layer of the lower anti-reflection layer 12, the light-shielding layer 13, and the upper anti-reflection layer 14, as shown in FIG. As shown in Fig. 2, the photoresist layer 15 may be formed in advance.

In addition, the mask blank 10B according to the present embodiment is, in addition to the lower antireflection layer 12, the light shielding layer 13, and the top antireflection layer 14, a drug resistant layer, a protective layer, an adhesion layer, an etching stopper layer, etc. It may be of a laminated configuration. Further, on such a laminated film, as shown in Fig. 2, a photoresist layer 15 may be formed.

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

In this embodiment, as the glass substrate (transparent substrate) 11, a rectangular substrate having a side of about 100 mm and a side of 2000 mm or more can be applied, and a substrate having a thickness of 1 mm or less, a substrate having a thickness of several mm, or A substrate with a thickness of 10 mm or more can also be used.

Further, the flatness of the glass substrate 11 may be reduced by polishing the surface of the glass substrate 11. The flatness of the glass substrate 11 can be made 20 micrometers or less, for example. For this reason, the depth of focus of the mask becomes deep, and it becomes possible to greatly contribute to the formation of fine and high-precision patterns. Further, it is preferable that the flatness is a small value of 10 µm or less.

The lower reflection prevention layer 12 has Cr (chromium) as a main component. The anti-reflection layer 12 contains C (carbon), O (oxygen), and N (nitrogen).

In addition, the anti-reflection layer 12 may have a different composition in the thickness direction. Further, in this case, as the lower reflection prevention layer 12, a single material of Cr, and one material selected from oxides, nitrides, carbides, oxynitrides, carbonitrides and oxycarbide nitrides of Cr, or two or more materials are used. It can also be constructed by laminating.

The lower anti-reflection layer 12, as described later, to obtain a predetermined optical properties and etching rate, the thickness of the lower anti-reflection layer 12, and the composition ratio (atm%) of Cr, N, C, O, etc. is set. do.

For example, the lower antireflection layer 12 is an oxynitride carbide film containing chromium, oxygen, nitrogen, and carbon, and the composition ratio in the lower antireflection layer 12 is 25 atm% ~ 50 Atm%, oxygen content (oxygen concentration) is 30 atm% ~ 50 atm%, nitrogen content (nitrogen concentration) is 10 atm% ~ 30 atm%, carbon content (carbon concentration) is set to be 2 atm% ~ 5 atm%. I can.

The film thickness of the lower anti-reflection layer 12 is set according to the optical properties required for the lower anti-reflection layer 12 and changes according to the composition ratio of Cr, N, C, O, and the like. The film thickness of the anti-reflection layer 12 may be 25.0 nm to 35.0 nm.

For this reason, the reflectance including the glass substrate 11 may be set to 5% or less in the range of about 365 nm to 436 nm in wavelength, particularly in the exposure light of 436 nm in wavelength.

The light shielding layer 13 has Cr (chromium) as a main component. The light shielding layer 13 contains N (nitrogen).

In addition, the light shielding layer 13 may have a different composition in the thickness direction. In this case, the light shielding layer 13 may be composed of a single material of Cr, and one material selected from oxides, nitrides, carbides, oxynitrides, nitride carbides, and oxide carbides of Cr, or by stacking two or more materials. have.

As for the light-shielding layer 13, as described later, the thickness of the light-shielding layer 13 and the composition ratio (atm%) of Cr, N, C, O, etc. are set so that predetermined optical properties and etching rates can be obtained.

For example, the light shielding layer 13 may be a nitride film containing chromium and nitrogen, and may be set such that the content of chromium is 70 atm% to 95 atm%, and the content of nitrogen is 5 atm% to 20 atm%.

Alternatively, the light shielding layer 13 is a nitrided carbide film containing chromium, nitrogen, and carbon, the content of chromium is 70 atm% ~ 95 atm%, the content of nitrogen is 5 atm% ~ 20 atm%, the content of carbon is 0 atm It can be set to be between% and 15 atm%.

The film thickness of the light-shielding layer 13 is set in accordance with the optical characteristics required for the light-shielding layer 13 and changes according to the composition ratio of Cr, N, C, O, and the like. The film thickness of the light-shielding layer 13 can be 125.0 nm to 135.0 nm.

The anti-reflection layer 14 has Cr (chromium) as a main component. The anti-reflection layer 14 contains C (carbon), O (oxygen), and N (nitrogen).

In addition, the anti-reflection layer 14 may have a different composition in the thickness direction. Further, in this case, as the anti-reflection layer 14, a single material of Cr, and one material selected from oxides, nitrides, carbides, oxynitrides, carbide nitrides, and oxide carbide nitrides of Cr, or two or more materials may be stacked. May be.

As will be described later, the anti-reflection layer 14 has its thickness and a composition ratio (atm%) of Cr, N, C, O, etc. so as to obtain predetermined optical properties and etching rates.

For example, the anti-reflection layer 14 is an oxynitride carbide film containing chromium, oxygen, nitrogen, and carbon, and the composition ratio in the anti-reflection layer 14 is 25 atm% to 50 atm%, More preferably, the content of chromium is 30 atm% ~ 50 atm%, the content of oxygen is 55 atm% ~ 70 atm%, the content of nitrogen is 5 atm% ~ 20 atm%, the content of carbon is 2 atm% ~ 5 It can be set to be atm%.

The film thickness of the anti-reflection layer 14 is set according to the optical properties required for the anti-reflection layer 14 and changes according to the composition ratio of Cr, N, C, O, and the like. The thickness of the anti-reflection layer 14 may be 25.0 nm to 35.0 nm.

For this reason, the anti-reflection layer 14 may have a reflectance of 5% or less in the range of about 365 nm to 436 nm in wavelength, particularly in exposure light having a wavelength of 436 nm.

For the mask layer in which the lower anti-reflection layer 12, the light blocking layer 13, and the upper anti-reflection layer 14 are stacked, the thickness of the mask layer may be 175.0 nm to 205.0 nm.

The mask blank 10B in this embodiment has the reflectance in exposure light having a wavelength of 436 nm on both sides of the mask layer in which the lower anti-reflection layer 12, the light-shielding layer 13 and the upper anti-reflection layer 14 are stacked. All can be set to 5% or less. In addition, in the mask layer in which the lower anti-reflection layer 12, the light blocking layer 13 and the upper anti-reflection layer 14 are stacked, the optical density may be set to be 3.0 or more.

In addition, in the mask blank 10B in this embodiment, the lower anti-reflection layer 12 and the light-shielding layer are formed by setting the composition ratio of the lower anti-reflection layer 12, the light-shielding layer 13, and the upper anti-reflection layer 14 to the above range. Since the etching rate of (13) and the anti-reflection layer 14 can be approached, it is possible to have a cross-sectional shape in which the occurrence of eaves and hem is reduced, as described later.

In the manufacturing method of the mask blank in this embodiment, after forming the lower reflection prevention layer 12 on the glass substrate (transparent substrate) 11, the light shielding layer 13 is formed, and thereafter, the upper reflection prevention layer 14 ) To the tabernacle.

In the case of laminating a protective layer, an adhesion layer, a chemical resistant layer, an etching stopper layer, etc., in addition to the lower anti-reflection layer 12, the light shielding layer 13 and the upper anti-reflection layer 14, the manufacturing method of the mask blank is these layers. It may have a lamination process of laminating.

As an example, an etching stopper layer containing metal silicide is mentioned, for example.

3 is a cross-sectional view showing a photomask in this embodiment.

The binary mask (photomask) 10 in this embodiment is, as shown in FIG. 3, a lower antireflection layer 12, a light shielding layer 13, and an upper antireflection layer 14 stacked as a mask blank 10B. ) Has a structure formed by patterning.

Hereinafter, the manufacturing method of manufacturing the photomask 10 from the mask blank 10B of this embodiment is demonstrated.

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, a mask blank 10B in which the photoresist layer 15 is formed on the outermost surface may be prepared in advance. The photoresist layer 15 may be of a positive type or a negative type. As the material of the photoresist layer 15, a material capable of responding to so-called etching to a chromium-based material is used. As the photoresist layer 15, a liquid resist is used.

Subsequently, by exposing and developing the photoresist layer 15, a resist pattern is formed outside the anti-reflection layer 14. The resist pattern functions as a mask used to etch the lower antireflection layer 12, the light shielding layer 13, and the upper antireflection layer 14.

The resist pattern is suitably shaped according to the etching patterns of the lower antireflection layer 12, the light shielding layer 13, and the upper antireflection layer 14. As an example, in the light-transmitting region, the resist pattern is set so as to have a shape having an opening width corresponding to the opening width dimension of the light shielding pattern to be formed.

Subsequently, as an anti-reflection pattern forming step, the anti-reflection layer 14 is wet etched using an etching solution over the resist pattern to form the anti-reflection pattern 14p.

As the etchant used in the anti-reflection pattern formation process, an etchant containing cerium nitrate second ammonium may be used, and for example, it is preferable to use cerium nitrate second ammonium nitrate containing an acid such as nitric acid or perchloric acid. .

Next, as a light-shielding pattern forming step, the light-shielding layer 13 is wet-etched using an etching solution over the top-reflection prevention pattern 14p to form the light-shielding pattern 13p.

As the etching solution used in the light-shielding pattern forming process, an etching solution containing cerium nitrate s2 ammonium can be used in the same manner as in the anti-reflection pattern forming process. For example, it is preferable to use cerium nitrate quaternary ammonium containing an acid such as nitric acid or perchloric acid.

Subsequently, as a lower reflection prevention pattern forming process, the patterned light shielding pattern 13p, the upper reflection prevention pattern 14p, and the lower reflection prevention layer 12 over the resist pattern are wet etched to form the lower reflection prevention pattern 12p. To form.

As an etchant used for the lower reflection prevention pattern formation step, an etchant containing cerium nitrate second ammonium can be used in the same manner as in the upper reflection prevention pattern formation step and the light-shielding pattern formation step. For example, it is preferable to use cerium nitrate quaternary ammonium containing an acid such as nitric acid or perchloric acid.

In addition, in the mask blank 10B in this embodiment, the lower anti-reflection layer 12 and the light-shielding layer are formed by setting the composition ratio of the lower anti-reflection layer 12, the light-shielding layer 13, and the upper anti-reflection layer 14 to the above range. (13) and the etching rate of the anti-reflection layer 14 can be approached. For this reason, after the formation of the upper reflection prevention pattern 14p, the light blocking pattern 13p, and the lower reflection prevention pattern 12p by etching, a good cross-sectional shape close to the vertical can be obtained as the cross-sectional shape of the photomask 10. have.

In addition, in the light-shielding pattern formation process, the composition ratio of the light-shielding layer 13 is set differently in the above-described range compared to the upper and lower antireflection layers 12 and 14, so that the etching rate is lowered compared to the case where no special setting is made. Therefore, compared with the etching in this case, the progress of the etching of the light-shielding pattern 13p is delayed. For this reason, the etching rate of the light shielding layer 13, the lower reflection prevention layer 12, and the top reflection prevention layer 14 can approach.

That is, the angle (taper angle) θ formed by the surface of the glass substrate 11 between the upper reflection prevention pattern 14p, the light blocking pattern 13p, and the lower reflection prevention pattern 12p approaches a right angle. For example, this angle θ can be set to about 90°. Further, the glass substrate 11 can be viewed from the normal direction, and the upper reflection prevention pattern 14p, the light blocking pattern 13p, and the lower reflection prevention pattern 12p can all be etched so that they have the same pattern shape.

Further, in the case of the mask blank 10B on which other films such as adhesion layers have been previously formed, the upper reflection prevention pattern 14p, the light blocking pattern 13p, and the lower reflection prevention pattern are performed by wet etching or the like using a corresponding etchant. Patterning is performed in a predetermined shape corresponding to (12p). Patterning of other films such as adhesion layers may be performed as a predetermined process before and after patterning of the lower anti-reflection layer 12, the light-shielding layer 13, and the upper anti-reflection layer 14 according to the stacking order.

In addition, for the lower antireflection layer 12, the light shielding layer 13, and the upper antireflection layer 14, by changing the oxygen concentration in the film thickness direction, respectively, it is possible to improve the cross-sectional shape after patterning.

Specifically, in the lower antireflection layer 12, the light shielding layer 13, and the upper antireflection layer 14, that is, the Cr film, the higher the oxygen concentration in the film, the lower the etching rate. For this reason, for the lower antireflection layer 12, the light shielding layer 13, and the upper antireflection layer 14, by increasing the oxygen concentration on the upper layer side than the oxygen concentration on the lower layer, the etching rate on the upper layer side is increased by etching the lower layer side. It can be lower than the rate.

At the same time, it is possible to set the etching rate and optical properties to a predetermined state by changing carbon, nitrogen, and other composition ratios other than oxygen in the film thickness direction.

As described above, the photomask 10 having the upper reflection prevention pattern 14p, the light blocking pattern 13p, and the lower reflection prevention pattern 12p is obtained as shown in FIG. 3.

Hereinafter, the manufacturing method of the mask blank in this embodiment is demonstrated based on drawings.

4 is a schematic diagram showing an apparatus for manufacturing a mask blank according to the present embodiment.

The mask blank 10B in this embodiment is manufactured by the manufacturing apparatus shown in FIG.

The manufacturing apparatus S10 shown in FIG. 4 is an interback type sputtering apparatus. The manufacturing apparatus S10 has a load chamber S11, an unload chamber S16, and a film forming chamber (vacuum processing chamber) S12. The film formation chamber S12 is connected to the load chamber S11 through a sealing mechanism S17, and is connected to the unload chamber S16 through a sealing mechanism S18.

In the load chamber S11, a conveyance mechanism S11a for conveying the glass substrate 11 carried in from the outside to the film formation chamber S12, and an exhaust mechanism such as a rotary pump for making a rough vacuum inside the load chamber S11 (S11f) ) Is installed.

In the unloading chamber S16, an evacuation mechanism such as 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, and a rotary pump for making the inside of the unloading chamber S16 a rough vacuum. (S16f) is installed.

In the film forming chamber S12, a substrate holding mechanism S12a and a three-stage film forming mechanism S13, S14, S15 are provided as a mechanism corresponding to the three film forming processes.

The substrate holding mechanism S12a holds the glass substrate 11 so as to face the targets S13b, S14b, and S15b during film formation of the glass substrate 11 conveyed by the transport mechanism S11a. The substrate holding mechanism S12a is capable of carrying in the glass substrate 11 from the load chamber S11 and carrying out the glass substrate 11 into the unload chamber S16.

In the structure of the film-forming chamber S12, a film-forming mechanism S13 for supplying the first-stage film-forming material among the three-stage film-forming mechanisms S13, S14, and S15 is provided at a position near the rod chamber S11.

The film forming mechanism S13 has a cathode electrode (backing plate) S13c having a target S13b and a power supply S13d for applying a sputter voltage of negative potential to the backing plate S13c.

The film formation mechanism S13 includes a gas introduction mechanism S13e that intensively introduces gas into a region in the vicinity of the cathode electrode (backing plate) S13c in the film formation chamber S12, and a cathode electrode in the film formation chamber S12. It has a high vacuum exhaust mechanism S13f such as a turbo molecular pump that focuses on a region near the backing plate) S13c to make high vacuum.

In addition, a film forming mechanism S14 that supplies a second-stage film-forming material among the three-stage film-forming mechanisms S13, S14, and S15 at a position between the load chamber S11 and the unload chamber S16 in the film-forming chamber S12. Is installed.

The film forming mechanism S14 has a cathode electrode (backing plate) S14c having a target S14b and a power supply S14d for applying a sputtering voltage of negative potential to the backing plate S14c.

The film formation mechanism S14 includes a gas introduction mechanism S14e for intensively introducing gas into a region in the vicinity of the cathode electrode (backing plate) S14c in the film formation chamber S12, and the cathode electrode in the film formation chamber S12. It has a high vacuum exhaust mechanism S14f such as a turbomolecular pump that focuses on a region near the backing plate) S14c to make high vacuum.

In addition, in the structure of the film formation chamber S12, a film formation mechanism S15 that supplies the film formation material of the third stage among the three stage film formation mechanisms S13, S14, S15 is provided at a position near the unload chamber S16. have.

The film forming mechanism S15 has a cathode electrode (backing plate) S15c having a target S15b and a power supply S15d for applying a sputter voltage of negative potential to the backing plate S15c.

The film formation mechanism S15 includes a gas introduction mechanism S15e for intensively introducing gas into a region in the vicinity of the cathode electrode (backing plate) S15c in the film formation chamber S12, and a cathode electrode in the film formation chamber S12. It has a high vacuum exhaust mechanism S15f such as a turbomolecular pump that focuses on a region near the backing plate) S15c to make high vacuum.

In the film formation chamber S12, in regions near the cathode electrodes (backing plates) S13c, S14c, and S15c, gases supplied from the gas introduction mechanisms S13e, S14e, and S15e, respectively, are supplied with the adjacent film formation mechanism S13, A gas barrier (S12g) for suppressing gas flow is provided so as not to be mixed into S14 and S15. These gas barriers S12g are configured so that the substrate holding mechanism S12a can move between the adjacent film forming mechanisms S13, S14, and S15, respectively.

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

In this embodiment, the film formation mechanism S13 corresponds to the film formation of the lower antireflection layer 12, the film formation mechanism S14 corresponds to the film formation of the light shielding layer 13, and the film formation mechanism S15 corresponds to the upper reflection radiation. It corresponds to the formation of the stratum 14.

Specifically, in the film forming mechanism S13, the target S13b is made of a material having chromium as a composition necessary for forming the lower reflection preventing layer 12 on the glass substrate 11.

At the same time, in the film formation mechanism S13, the gas supplied from the gas introduction mechanism S13e corresponds to the film formation of the lower reflection prevention layer 12, and the process gas contains carbon, nitrogen, oxygen, etc., and argon, nitrogen gas, etc. Together with the sputtered gas of, the condition is set as a predetermined gas partial pressure.

In addition, exhaust from the high vacuum exhaust mechanism S13f is performed in accordance with the film forming conditions.

Further, in the film forming mechanism S13, a sputtering voltage applied from the power source S13d to the backing plate S13c is set corresponding to the film formation of the lower reflection prevention layer 12.

Further, in the film forming mechanism S14, the target S14b is made of a material having chromium as a composition necessary for forming the light shielding layer 13 on the lower antireflection layer 12.

At the same time, in the film formation mechanism S14, the gas supplied from the gas introduction mechanism S14e corresponds to the film formation of the light shielding layer 13, and the process gas contains carbon, nitrogen, oxygen, etc. Together with the sputter gas, it is set as a predetermined gas partial pressure.

In addition, exhaust from the high vacuum exhaust mechanism S14f is performed in accordance with the film forming conditions.

Further, in the film forming mechanism S14, a sputtering voltage applied from the power supply S14d to the backing plate S14c is set corresponding to the film formation of the light-shielding layer 13.

Further, in the film forming mechanism S15, the target S15b is made of a material having chromium as a composition necessary for forming the anti-reflection layer 14 on the light-shielding layer 13.

At the same time, in the film formation mechanism S15, the gas supplied from the gas introduction mechanism S15e corresponds to the film formation of the anti-reflection layer 14, and the process gas contains carbon, nitrogen, oxygen, etc., and argon, nitrogen gas, etc. Together with the sputtered gas of, the condition is set as a predetermined gas partial pressure.

Further, exhaust from the high vacuum exhaust mechanism S15f is performed in accordance with the film forming conditions.

In addition, in the film forming mechanism S15, a sputtering voltage applied from the power source S15d to the backing plate S15c is set corresponding to the film formation of the upper reflection prevention layer 14.

In the manufacturing apparatus S10 shown in FIG. 4, with respect to the glass substrate 11 carried in from the load chamber S11 by the conveyance mechanism S11a, the substrate holding mechanism S12a in the film formation chamber (vacuum processing chamber) S12 The sputtering film is formed in three stages while being conveyed by means of. After that, the glass substrate 11 on which film formation has been completed is carried out from the unloading chamber S16 to the outside by the transport mechanism S16a.

In the lower reflection prevention layer forming step, the sputter gas and the reactive gas are supplied as supply gases from the gas introduction mechanism S13e to the region near the backing plate S13c of the film forming chamber S12 in the film forming mechanism S13. In this state, a sputtering voltage is applied to the backing plate (cathode electrode) S13c from an external power source. Further, a predetermined magnetic field may be formed on the target S13b by a magnetron magnetic circuit.

Ions of the sputter gas excited by the plasma in the region near the backing plate S13c in the film formation chamber S12 collide with the target S13b of the cathode electrode S13c, causing particles of the film formation material to protrude. Then, after the protruding particles and the reactive gas are bonded, the lower reflection prevention layer 12 is formed on the surface of the glass substrate 11 with a predetermined composition by adhering to the glass substrate 11.

Similarly, in the light-shielding layer forming step, the sputtering gas and the reactive gas are supplied as supply gases from the gas introduction mechanism S14e to the region near the backing plate S14c of the film forming chamber S12 in the film forming mechanism S14. In this state, a sputtering voltage is applied to the backing plate (cathode electrode) S14c from an external power source. Further, a predetermined magnetic field may be formed on the target S14b by a magnetron magnetic circuit.

Ions of the sputter gas excited by the plasma in the region near the backing plate S14c in the film formation chamber S12 collide with the target S14b of the cathode electrode S14c, causing particles of the film formation material to protrude. Then, after the protruding particles and the reactive gas are combined, the light-shielding layer 13 is formed on the surface of the lower anti-reflection layer 12 with a predetermined composition by adhering to the lower anti-reflection layer 12.

Similarly, in the anti-reflection layer forming step, sputter gas and reactive gas are supplied as supply gases from the gas introduction mechanism S15e to the region near the backing plate S15c of the film forming chamber S12 in the film forming mechanism S15. In this state, a sputter voltage is applied to the backing plate (cathode electrode) S15c from an external power source. Further, a predetermined magnetic field may be formed on the target S15b by a magnetron magnetic circuit.

Ions of the sputter gas excited by the plasma in the region near the backing plate S15c in the film formation chamber S12 collide with the target S15b of the cathode electrode S15c, causing particles of the film formation material to protrude. Then, after the protruding particles and the reactive gas are combined, the anti-reflection layer 14 is formed on the surface of the light-shielding layer 13 with a predetermined composition by adhering to the light-shielding layer 13.

At this time, in the film formation of the lower antireflection layer 12, a nitrogen-containing gas, an oxygen-containing gas, a carbon-containing gas, a sputtering gas, etc. that have a predetermined partial pressure are supplied from the gas introduction mechanism S13e to control the partial pressure. The composition of the antireflection layer 12 is set within a set range.

In the film formation of the light shielding layer 13, a nitrogen-containing gas, an oxygen-containing gas, a carbon-containing gas, a sputtering gas, etc., which have a predetermined partial pressure are supplied from the gas introduction mechanism S14e to control the partial pressure, and the light-shielding layer ( The composition of 13) is within the set range.

At this time, in the film formation of the anti-reflection layer 14, a nitrogen-containing gas, an oxygen-containing gas, a carbon-containing gas, a sputtering gas, etc. that have a predetermined partial pressure are supplied from the gas introduction mechanism S15e to control the partial pressure. The composition of the anti-glare layer 14 is within the set range.

Here, examples of the oxygen-containing gas include CO ₂ (carbon dioxide), O ₂ (oxygen), N ₂ O (dinitrogen monoxide), NO (nitrogen monoxide), and CO (carbon monoxide).

Further, examples of the carbon-containing gas include CO ₂ (carbon dioxide), CH ₄ (methane), C ₂ H ₆ (ethane), and CO (carbon monoxide).

In addition, the targets S13b, S14b, and S15b may be exchanged if necessary by forming the lower antireflection layer 12, the light shielding layer 13, and the upper antireflection layer 14.

Further, in addition to the formation of the lower anti-reflection layer 12, the light shielding layer 13, and the upper anti-reflection layer 14, other films may be laminated. In this case, the film is formed by sputtering under sputtering conditions such as targets and gases corresponding to the material of the other film, or the film is laminated according to another film forming method to manufacture the mask blank 10B of the present embodiment.

Hereinafter, the film characteristics of the lower anti-reflection layer 12, the light shielding layer 13, and the upper anti-reflection layer 14 in the present embodiment will be described.

First, on the glass substrate 11 for forming a mask, a chromium compound film serving as the main component film of the lower antireflection layer 12 is formed by using a sputtering method or the like. The chromium compound film formed at this time is preferably a film containing chromium, oxygen, nitrogen, carbon, or the like. By controlling the composition and film thickness of chromium, oxygen, nitrogen, and carbon contained in the film of the anti-reflection layer 12, it is possible to form the anti-reflection layer 12 having desired optical properties and etching rate. The chromium compound is suitable for use in an interface in contact with a photoresist because of its strong chemical resistance to acid or alkali solutions and hydrophobic properties.

Then, a chromium compound film to be the light-shielding layer 13 is formed using a sputtering method or the like.

Here, when the light-shielding layer 13 is formed only with the chromium compound film, and there is no other film, the reflectance is increased to about 25%. For this reason, it is preferable to reduce the reflectance by forming the upper and lower antireflection layers 12 and 14 serving as low reflection layers on the front and rear surfaces of the light shielding layer 13.

By laminating the lower anti-reflection layer 12, the light shielding layer 13, and the upper anti-reflection layer 14 in this way, it is a material of a chromium compound with strong chemical resistance, and a high optical density (OD5) required for the photomask 10 and required etching A mask layer having a rate or the like can be formed.

_{Specifically, Ar, NO, and CO 2} can be selected as the gas used for the formation of the lower anti-reflection layer 12 and the upper anti-reflection layer 14. Here, by setting the ratio of NO:CO ₂ gas as 1:10 to 10:1, a good cross-sectional shape with few eaves and hem can be obtained. Further, it was found that the reflectance of 10% or less for exposure light having a wavelength of 365 nm to 436 nm, and particularly, a reflectance of 5% or less for exposure light having a wavelength of 436 nm, can be achieved.

In addition, by setting the film thicknesses of the lower anti-reflection layer 12, the light shielding layer 13, and the upper anti-reflection layer 14 in the ranges of 25.0 nm to 35.0 nm, 125.0 nm to 135.0 nm, and 25.0 nm to 35.0 nm, respectively. It was found that the photomask 10 had a high optical density (OD5) required for the photomask 10.

Example

Subsequently, the composition ratio in the film formation of the lower anti-reflection layer 12, the light-shielding layer 13, and the upper anti-reflection layer 14 is verified.

<Example 1>

A chromium compound serving as a three-layer mask layer was formed on a glass substrate by a sputtering method.

When forming the chromium compound film serving as the light-shielding layer, it was sputtered with nitrogen gas.

When forming the chromium compound film serving as the upper and lower antireflection layers, it was sputtered with nitrogen gas. _{Further, CO 2} gas and NO gas were selected as the oxidizing gas, and the partial pressures were changed in each gas. Table 1 shows the gas ratio.

In addition, the film thickness of the lower anti-reflection layer 12, the film thickness of the light-shielding layer 13, the film thickness of the upper anti-reflection layer 14, and the total film thickness of the mask layer are shown in Table 2 below.

Changes in the composition ratios of N, O, Cr, and C in each layer of Example 1 were determined by Auger electron spectroscopy. The results are shown in Table 3.

In addition, the spectral reflectance of the surface (top-reflective layer side) according to the wavelength in Example 1 is shown in FIGS. 5 and 4.

Similarly, the spectral reflectance of the back surface (glass substrate side) according to the wavelength in Example 1 is shown in Figs. 6 and 5.

As a result of these results, in Example 1, the reflectance of both the surface and the back view and the exposure light having a wavelength of 365 nm to 436 nm is 10% or less, and in particular, for the exposure light having a wavelength of 436 nm, the reflectance is 5% or less. I can see that there is.

<Example 2>

A chromium compound serving as a three-layer mask layer was formed on a glass substrate by a sputtering method.

When forming the chromium compound film serving as the light-shielding layer, it was sputtered with nitrogen gas.

When forming the chromium compound film serving as the upper and lower antireflection layers, it was sputtered with nitrogen gas. _{Further, CO 2} gas and NO gas were selected as the oxidizing gas, and the partial pressures were changed in each gas. Table 1 shows the gas ratio.

In addition, the film thickness of the lower anti-reflection layer 12, the film thickness of the light-shielding layer 13, the film thickness of the upper anti-reflection layer 14, and the total film thickness of the mask layer are shown in Table 2 below.

Changes in the composition ratios of N, O, Cr, and C in each layer of Example 2 were determined by Auger electron spectroscopy. The results are shown in Table 6.

In addition, the spectral reflectance of the surface (top-reflective layer side) according to the wavelength in Example 2 is shown in FIGS. 5 and 4.

Similarly, the spectral reflectance of the back surface (glass substrate side) according to the wavelength in Example 2 is shown in Figs. 6 and 5.

From these results, in Example 2, the reflectance of both the front and back views and the exposure light having a wavelength of 365 nm to 436 nm is 10% or less, and in particular, for the exposure light having a wavelength of 436 nm, the reflectance is 5% or less. I can see that there is.

<Comparative Examples 1 to 3>

In the same manner as in Example 1 described above, a chromium compound serving as a three-layer mask layer was formed by using a sputtering method.

In Comparative Examples 1 and 3, when forming a chromium compound film serving as a light-shielding layer, sputtering was performed with argon gas and nitrogen gas. In Comparative Example 2, when forming a chromium compound film serving as a light-shielding layer, it was sputtered with nitrogen gas, argon gas, and methane gas.

When forming the chromium compound serving as the upper and lower antireflection layers, it was sputtered with nitrogen gas. _{Further, CO 2} gas and NO gas were selected as the oxidizing gas, and the partial pressures were changed in each gas. Table 1 shows the gas ratio.

In addition, the film thicknesses of the lower anti-reflection layer 12, the light shielding layer 13, and the upper anti-reflection layer 14, and the total film thickness as a mask layer are shown in Table 2 below.

Changes in the composition ratios of N, O, Cr, and C in each layer of Comparative Examples 1 to 3 were determined by Auger electron spectroscopy. The results are shown in Tables 7 to 9.

In addition, the spectral reflectance of the surface (top-reflective layer side) according to the wavelength in Comparative Examples 1 to 3 is shown in FIGS. 5 and 4.

Similarly, the spectral reflectance of the back surface (glass substrate side) according to the wavelength in Comparative Examples 1 to 3 is shown in Figs. 6 and 5.

From these results, in Comparative Examples 1 to 3, the reflectance in exposure light having a wavelength of 365 nm to 436 nm on the surface was 10% or less, and in Comparative Example 2, in exposure light having a wavelength of 365 nm to 436 nm on the back surface. It can be seen that the reflectance of is less than 10%. However, in Comparative Examples 1 and 3, it can be seen that the reflectance on the back surface is not less than 10%.

According to the purpose of the light shielding layer and the antireflection layer, it is necessary to greatly change the gas composition ratio in the film of each layer. The light shielding layer needs to reduce oxidizing gas in order to take a high optical concentration (eg, OD5). In addition, the antireflection layer needs to contain a large amount of oxidizing gas in the film in order to reduce the reflectance. For this reason, the gas composition ratio in the film is greatly different between the light shielding layer and the antireflection layer, resulting in a difference in etching rate.

Next, the etching shape in the film formation of the lower reflection prevention layer 12, the light shielding layer 13, and the top reflection prevention layer 14 is verified.

<Example 1>

The mask blanks prepared in Example 1 were patterned (resist coating, exposure, development, and etching), and the cross-sectional shape of the mask blanks was observed by SEM. The results are shown in FIG. 7. Further, a bird's eye view at the patterning boundary is shown in FIG. 12.

In addition, the magnification in FIG. 7 is 80000 times. The magnification in Fig. 12 is 30000 times.

As a result, in Experimental Example 1, the eaves (the length of the upper anti-reflection layer protruding from the light-shielding layer): 50 nm, and the hem (the length of the lower anti-reflection layer protruding from the light-shielding layer): 59 nm.

<Example 2>

The mask blanks prepared in Example 2 were patterned (resist coating, exposure, development, and etching), and the cross-sectional shape of the mask blanks was observed by SEM. The results are shown in FIG. 8. Further, a bird's eye view at the patterning boundary is shown in FIG. 13.

In addition, the magnification in FIG. 8 is 80000 times. The magnification in Fig. 13 is 30000 times.

As a result, in Experimental Example 2, the eaves (the length of the upper anti-reflection layer protruding from the light-shielding layer): 57 nm, and the hem (the length of the lower anti-reflection layer protruding from the light-shielding layer): 40 nm.

<Comparative Example 1>

In the same manner as in Example 1, patterning (resist coating, exposure, development, and etching) was performed on the created mask blank, and its cross-sectional shape was observed by SEM. The results are shown in FIG. 9. Further, a bird's eye view at the patterning boundary is shown in FIG. 14.

In addition, the magnification in FIG. 9 is 80000 times. The magnification in Fig. 14 is 30000 times.

As a result, in Comparative Example 1, the eaves (the length of the upper anti-reflection layer protruding from the light-shielding layer): 79 nm, and the hem (the length of the lower anti-reflection layer protruding from the light-shielding layer): 145 nm.

<Comparative Example 2>

In the same manner as in Example 1, patterning (resist coating, exposure, development, and etching) was performed on the created mask blank, and its cross-sectional shape was observed by SEM. The results are shown in FIG. 10. Further, a bird's eye view at the patterning boundary is shown in FIG. 15.

In addition, the magnification in FIG. 10 is 80000 times. The magnification in Fig. 15 is 30000 times.

As a result, in Comparative Example 2, the eaves (the length of the upper anti-reflection layer protruding from the light-shielding layer): 140 nm, and the bottom end (the length of the lower anti-reflection layer protruding from the light-shielding layer): 52 nm.

<Comparative Example 3>

In the same manner as in Example 1, patterning (resist coating, exposure, development, and etching) was performed on the created mask blank, and its cross-sectional shape was observed by SEM. The results are shown in Fig. 11. In addition, a bird's eye view at the patterning boundary is shown in Fig. 16.

In addition, the magnification in FIG. 11 is 80000 times. The magnification in Fig. 16 is 30000 times.

As a result, in Comparative Example 3, the eaves (the length of the upper anti-reflection layer protruding from the light-shielding layer): 128 nm, and the hem (the length of the lower anti-reflection layer protruding from the light-shielding layer): 154 nm.

From these results, in Comparative Examples 1 to 3, it was confirmed that the antireflection layer on the glass layer side (back) and the antireflection layer on the upper side (surface) were both in the shape of the light-shielding layer compared to the light-shielding layer (the upper layer was Eaves shape, lower layer hem shape). This is due to the difference in the etching rate between the antireflection layer and the light shielding layer.

It is understood that the mask blank of the present invention can form a good cross-sectional shape, and thus a high-precision photomask can be manufactured.

10: photo mask
10B: Mask blanks
11: Glass substrate (transparent substrate)
12: anti-reflection layer
12p: Anti-reflective pattern
13: Light-shielding layer
13p: shading pattern
14: anti-reflection layer
14p: Anti-reflection pattern

Claims (9)

As a mask blank having a mask layer that becomes a photomask,
The mask layer,
An anti-reflection layer laminated on a transparent substrate,
A light-shielding layer provided at a position spaced apart from the transparent substrate than the lower anti-reflection layer, and
An anti-reflection layer provided at a position separated from the transparent substrate from the light blocking layer,
To have,
The anti-reflective layer is an oxynitride carbide film containing chromium, oxygen, nitrogen, and carbon, and the content of chromium in the lower anti-reflective layer is 25 atm% to 50 atm%, and the oxygen contained in the lower anti-reflective layer is The content rate is 30 atm% ~ 50 atm%, the content rate of nitrogen contained in the lower reflection prevention layer is 10 atm% ~ 30 atm%, the content rate of carbon contained in the lower reflection prevention layer is 2 atm% ~ 5 atm%. ,
The light-shielding layer is a nitride film containing chromium and nitrogen, the content of chromium in the light-shielding layer is 70 atm% to 95 atm%, and the content of nitrogen is 5 atm% to 20 atm%,
The anti-reflection layer is an oxynitride carbide film containing chromium, oxygen, nitrogen, and carbon, and the content of chromium in the anti-reflection layer is 25 atm% to 50 atm%, and the oxygen contained in the anti-reflection layer is The content rate is 55 atm% ~ 70 atm%, the content rate of nitrogen included in the anti-reflection layer is 5 atm% ~ 20 atm%, and the content rate of carbon included in the anti-reflection layer is 2 atm% ~ 5 atm%. , Mask Blanks. As a mask blank having a mask layer that becomes a photomask,
The mask layer,
An anti-reflection layer laminated on a transparent substrate,
A light-shielding layer provided at a position spaced apart from the transparent substrate than the lower anti-reflection layer, and
An anti-reflection layer provided at a position separated from the transparent substrate from the light blocking layer,
To have,
The anti-reflective layer is an oxynitride carbide film containing chromium, oxygen, nitrogen, and carbon, and the content of chromium in the lower anti-reflective layer is 25 atm% to 50 atm%, and the oxygen contained in the lower anti-reflective layer is The content rate is 30 atm% ~ 50 atm%, the content rate of nitrogen contained in the lower reflection prevention layer is 10 atm% ~ 30 atm%, the content rate of carbon contained in the lower reflection prevention layer is 2 atm% ~ 5 atm%. ,
The light-shielding layer is a nitride carbide film containing chromium, nitrogen, and carbon, the content of chromium in the light-shielding layer is 70 atm% ~ 95 atm%, and the content of nitrogen in the light-shielding layer is 5 atm% ~ 20 atm%, and the content of carbon included in the light blocking layer is 0 atm% to 15 atm%,
The anti-reflection layer is an oxynitride carbide film containing chromium, oxygen, nitrogen, and carbon, and the content of chromium in the anti-reflection layer is 25 atm% to 50 atm%, and the oxygen contained in the anti-reflection layer is The content rate is 55 atm% ~ 70 atm%, the content rate of nitrogen included in the anti-reflection layer is 5 atm% ~ 20 atm%, and the content rate of carbon included in the anti-reflection layer is 2 atm% ~ 5 atm%. , Mask Blanks. The method according to claim 1 or 2,
On both sides of the mask layer, the reflectance in exposure light having a wavelength of 365 nm to 436 nm is 10% or less. The method of claim 3,
On both sides of the mask layer, all of the reflectances in exposure light having a wavelength of 436 nm are 5% or less. The method according to claim 1 or 2,
In the mask layer, a film thickness of the lower reflection prevention layer, a film thickness of the light-shielding layer, and a film thickness of the top reflection prevention layer are set so that the optical density is 3.0 or more. The method of claim 5,
The film thickness of the anti-reflection layer is 25.0 nm to 35.0 nm,
The thickness of the light blocking layer is 125.0 nm to 135.0 nm,
The anti-reflection layer has a thickness of 25.0 nm to 35.0 nm, mask blanks. The method of claim 6,
The mask blanks, wherein the mask layer has a thickness of 175.0 nm to 205.0 nm. The method of claim 1,
A mask blank having a photoresist layer provided at a position separated from the transparent substrate rather than the mask layer. A photomask manufactured from the mask blanks according to claim 1.

Images