JP2020086087A - Mask blank and mask - Google Patents

Abstract

To prevent degradation in a pattern profile of a mask while maintaining optical specifications.SOLUTION: A mask blank is provided, which has a transparent substrate S, light-shielding layers 11A, 11B formed on the transparent substrate and essentially comprising chromium, and an antireflection layer 13 formed in contact with the light-shielding layer and essentially comprising chromium, and which has an etching rate reduction layer 12 having a reduced etching rate than that of the light-shielding layer at a position where the light-shielding layer is not in contact with the antireflection layer in the thickness direction.SELECTED DRAWING: Figure 1

Description

The present invention relates to a mask blank and a mask, and particularly to a technique suitable for use in a large area mask blank and a mask.

Substrates for FPDs (flat panel displays, flat panel displays) such as liquid crystal displays and organic EL displays are manufactured by using a plurality of masks.

As described in Patent Documents 1 and 2, a photomask for a large plate used for manufacturing an FPD or the like is subjected to a patterning process on a mask blank in which a light shielding layer containing a metal such as chromium is formed on a glass substrate. By applying, a binary mask having a desired pattern is formed.
In a photomask for a large plate used for manufacturing an FPD or the like, pattern formation is performed by wet etching.

In recent years, in both liquid crystal displays and organic EL displays, the high definition of panels has been greatly advanced, and the miniaturization of photomasks has been advanced accordingly. It is necessary to form a fine pattern in order to miniaturize the photomask. To create a fine pattern, it is necessary to use a mask having a higher optical density in order to increase the contrast of the pattern.

Further, if the reflected light is larger than the transmitted light passing through the mask at the time of exposure, there arises a problem that the accuracy of the pattern transferred by exposure is lowered.
In the mask having the structure in which the antireflection layer and the light shielding layer are formed on the surface, the reflectance of the surface is defined by the difference in refractive index between the antireflection layer and the light shielding layer and the film thickness thereof.

As a measure against the above problem, a mask satisfying the optical specifications of the conventional optical density OD5 and the reflectance of 5% or less has recently been demanded as a mask for a high-definition flat panel display. That is, as a mask for a high-definition flat panel display, a mask having a high optical density and a low reflectance is required.

JP, 2007-212738, A International Publication No. 2007/099910

However, it has been found that when a mask is prepared by using a mask blank satisfying the above optical specifications as a mask, the cross-sectional shape of the pattern is deteriorated and various problems occur.

Specifically, it is a problem of deterioration of the shape of the fine pattern.

Chromium, which has excellent chemical resistance and is easy to wet-etch, is usually used as a mask for flat displays.
In order to form an antireflection layer using chromium, it is necessary to increase the oxygen concentration in the antireflection layer made of chromium to lower the refractive index than the light-shielding layer in order to reduce the reflectance. .. Usually, when wet etching chromium, a wet etching solution containing cerium secondary ammonium nitrate is used.

However, if the oxygen concentration in the chromium film is increased, the etching rate will decrease. As a result, the etching rate greatly differs between the light shielding layer and the antireflection layer. Further, in order to increase the optical density, the film thickness of the light shielding layer also becomes thick.

Therefore, it has been found that a mask satisfying the above optical specifications has a cross-sectional shape in which only the central portion is largely etched in the film thickness direction.
That is, the conventional technique has a problem in that it is not possible to manufacture a mask having a good cross-sectional shape that satisfies the above optical specifications.

Further, regarding the reflected light from the mask, it is desirable to reduce the reflected light on both sides of the mask pattern side and the mask substrate side. Therefore, antireflection layers may be provided on both sides which are the front and back surfaces of the mask. In this case, as described above, there is a problem that the pattern shape is further deteriorated.

The present invention has been made in view of the above circumstances, and aims to achieve the following objects.
1. Achieve higher optical density masks.
2. Achieve a mask with lower reflectance.
3. Preventing the deterioration of the shape of fine patterns.
4. To achieve the above objectives at the same time.

The mask blank of the present invention includes a transparent substrate,
A light-shielding layer formed on the transparent substrate and containing chromium as a main component;
An antireflection layer formed in contact with the light shielding layer and containing chromium as a main component;
Have
The above problem is solved by providing the light shielding layer with an etching rate reducing layer having an etching rate lower than that of the light shielding layer, at a position not in contact with the antireflection layer in the thickness direction.
In the mask blank of the present invention, the etching rate reducing layer may be provided in a single layer or a plurality of layers in the thickness direction of the light shielding layer.
In the mask blank of the present invention, it is preferable that the etching rate reducing layer is provided at a central portion in the thickness direction of the light shielding layer.
In the mask blank of the present invention, the etching rate reducing layer can have a higher oxygen concentration than the light shielding layer.
Further, in the mask blank of the present invention, it is possible to employ a means in which the etching rate reducing layer has a higher carbon concentration than the light shielding layer.
In the mask blank of the present invention, the oxygen concentration of the light-shielding layer is higher than that of the etching rate reducing layer in contact with the transparent substrate side in the film thickness direction, and further compared to the oxygen concentration of the light-shielding layer located on the transparent substrate side. Can be set higher.
Further, in the mask blank of the present invention, the carbon concentration of the light shielding layer is more than the etching rate reducing layer in contact with the transparent substrate side in the film thickness direction, and further, the carbon concentration of the light shielding layer located on the transparent substrate side. Can be set to be higher than.
The mask blank of the present invention has a wavelength λ of exposure light used in a range of 365 nm to 436 nm,
The OD value can be set higher than 5 and the reflectance lower than 5%.
In the mask blank of the present invention, in the light shielding layer in contact with the antireflection layer, the film thickness up to the etching rate reducing layer can be set to λ*20/405 or more with respect to the wavelength λ. .
In the mask blank of the present invention, the film thickness of the antireflection layer is in the range of λ*25/405 to λ*30/405 or λ*95/405 to λ*100/405 with respect to the wavelength λ. Can be set.
The mask of the present invention can be manufactured using any of the mask blanks described above.

The mask blank of the present invention includes a transparent substrate,
A light-shielding layer formed on the transparent substrate and containing chromium as a main component;
An antireflection layer formed in contact with the light shielding layer and containing chromium as a main component;
Have
The light-shielding layer has an etching rate reduction layer having an etching rate lower than that of the light-shielding layer, at a position not in contact with the antireflection layer in the thickness direction.
In other words, the light shielding layer itself is divided in the thickness direction by the etching rate reducing layer provided in the middle of the light shielding layer in the thickness direction.

As a result, mask blanks capable of satisfying desired optical specifications as a mask can be realized. This optical specification is to maintain the desired state initially set by setting the structure near the interface between the antireflection layer and the light shielding layer, and the film thickness and composition of the antireflection layer and the light shielding layer. is important.
Further, the desired optical specifications as a mask means that the value of the optical density OD and the value of the reflectance are maintained in a desired state with respect to the exposure light having the predetermined wavelength λ required in the exposure process when the mask is used. Means to do.

Further, when the optical specifications are satisfied, it is possible to prevent the deterioration of the shape in the pattern formation, which was not possible in the past.
The deterioration of the shape in the pattern formation means that a recess is formed on the side surface of the light-shielding layer after the etching and the line width of the pattern does not maintain a predetermined pattern.

Here, the deterioration of the shape in pattern formation is caused by the difference in the etching rate of wet etching in pattern formation between the antireflection layer and the light shielding layer.
However, it is impossible to eliminate the difference in etching rate between the antireflection layer and the light shielding layer in order to satisfy the above-mentioned optical specifications by the conventional technique.

That is, in the present invention, it is possible to prevent the pattern shape after etching from deteriorating and maintain the optical density OD value and the reflectance value in a desired state with respect to the exposure light. ..

Further, in the FPD field, in the exposure process when a mask is used, exposure using a composite wavelength composed of i-line (wavelength 365 nm), h-line (wavelength 403 nm), and g-line (wavelength 436 nm) as the exposure light wavelength λ Pattern formation is performed.

Further, in the present invention, the value of the optical density OD and the value of the reflectance are maintained in a desired state as compared with the case where a composite wavelength composed of i-line, h-line and g-line is used as the wavelength of the exposure light. At the same time, it is possible to prevent deterioration of the pattern shape of the mask after etching. Alternatively, even when the exposure light having a single wavelength of any of these i-line, h-line, and g-line is used, the value of the optical density OD and the value of the reflectance are maintained in a desired state, It is possible to prevent deterioration of the pattern shape of the mask after etching.

In the mask blank of the present invention, the etching rate reducing layer is provided in one or more layers in the thickness direction of the light shielding layer.
Thereby, the value of the optical density OD and the value of the reflectance can be maintained in desired states, and deterioration of the pattern shape of the mask after etching can be prevented. In particular, by setting the etching rate of the etching rate reduction layer to be lower than the etching rate of the light shielding layer, it is possible to prevent the light shielding layer from being largely etched from the side surface during wet etching during pattern formation.

This is because when the light-shielding layer is etched subsequently to the antireflection layer, the dimension in the depth (thickness) direction of one light-shielding layer becomes smaller, so that the portion having a small etching rate is reduced and the light-shielding layer is reduced. This is because the etching amount in the lateral direction in the depth direction (direction parallel to the surface of the transparent substrate) is suppressed.

Further, optically, since the etching rate reduction layer corresponding to the light shielding layer remains without being etched with respect to the light shielding layer, the etching rate reduction layer corresponding to the light shielding layer when viewed in the direction perpendicular to the surface of the transparent substrate. However, it is possible to form a pattern with substantially the same contour shape as the antireflection layer.

In other words, the light-shielding layer divided in the thickness direction by the plurality of etching rate reducing layers provided in the vicinity of the interface between the etching rate reducing layer and the light-shielding layer, the light-shielding layer from the side by wet etching during pattern formation. It can be prevented from being greatly etched.

The etching rate of the etching rate reduction layer can be set to be equal to or smaller than the etching rate of the antireflection layer.

The etching rate reducing layer can be provided in the light shielding layer as one layer, two layers or three layers. The number of layers of the etching rate reducing layer, that is, the number of divisions of the light shielding layer can be set from the wavelength of exposure light in pattern formation.

In the mask blank of the present invention, the etching rate reducing layer is provided in the central portion of the light shielding layer in the thickness direction.
Thus, the structure near the interface between the antireflection layer and the light-shielding layer, and the optical specifications set by the film thickness and composition of the antireflection layer and the light-shielding layer can maintain the desired initial conditions. it can.
Here, the central portion in the thickness direction means that the film thickness of the light-shielding layer in contact with the antireflection layer side maintains a range necessary for setting the reflectance to a predetermined value, and the etching rate reducing layer is the light-shielding layer. It means that it is not in contact with other layers including the antireflection layer except for.

Furthermore, this makes it possible to prevent the deterioration of the pattern shape after etching without affecting the optical specifications set in the light-shielding layer with the other layer provided on the side opposite to the antireflection layer. .. In particular, in the case of the structure in which the antireflection layers are provided on both sides of the light shielding layer, the reflectance set between the both antireflection layers can be set to the above specifications to prevent the deterioration of the shape.

In the mask blank of the present invention, the etching rate reducing layer has a higher oxygen concentration than the light shielding layer.
Thereby, the etching rate reduction layer can have a lower etching rate than the light shielding layer.

In the mask blank of the present invention, the etching rate reducing layer has a carbon concentration higher than that of the light shielding layer.
Thereby, the etching rate reduction layer having a high oxygen concentration can have an even lower etching rate.
Further, the high carbon concentration can further reduce the etching rate.

In the mask blank of the present invention, the oxygen concentration of the light-shielding layer is higher than that of the etching rate reducing layer in contact with the transparent substrate side in the film thickness direction, and further compared to the oxygen concentration of the light-shielding layer located on the transparent substrate side. Is set to be higher.
As a result, the light-shielding layer that is etched earlier can have a lower etching rate than the light-shielding layer that is etched later. That is, the light-shielding layer near the antireflection layer, which has been etched for a long time, can have a lower etching rate than the light-shielding layer, which has a shorter etching time.

Therefore, as compared with the light-shielding layer on the side closer to the transparent substrate, in the light-shielding layer on the side farther from the transparent substrate, from the side surface of the light-shielding layer toward the back, that is, with respect to the direction parallel to the surface of the transparent substrate. The etching amount can be reduced.
As a result, etching is performed in positions in different thickness directions with respect to the transparent substrate, that is, in the light shielding layer having different distances from the transparent substrate, from the side surface of the light shielding layer toward the back, that is, in the direction parallel to the surface of the transparent substrate. It is possible to equalize the amounts. Thereby, the deterioration of the pattern shape after etching can be further prevented.

Further, in the mask blank of the present invention, the carbon concentration of the light shielding layer is more than the etching rate reducing layer in contact with the transparent substrate side in the film thickness direction, and further, the carbon concentration of the light shielding layer located on the transparent substrate side. It is set to be higher than.
This further reduces the etching rate in the light-shielding layers whose oxygen concentration is set to a predetermined state in the light-shielding layers having different thickness positions with respect to the transparent substrate, that is, different distances from the transparent substrate. It is possible to set the etching rate corresponding to the position in the thickness direction.
Further, by setting the carbon concentration stepwise corresponding to the position in the thickness direction, the etching rate in the depth direction of the light shielding layer can be controlled.
As a result, etching is performed in positions in different thickness directions with respect to the transparent substrate, that is, in the light shielding layer having different distances from the transparent substrate, from the side surface of the light shielding layer toward the back, that is, in the direction parallel to the surface of the transparent substrate. It is possible to equalize the amounts. Thereby, the deterioration of the pattern shape after etching can be further prevented.

The mask blank of the present invention has a wavelength λ of exposure light used in a range of 365 nm to 436 nm,
The OD value is set higher than 5 and the reflectance is set lower than 5%.
By satisfying such optical specifications, it is possible to provide a mask blank that can be used for manufacturing a high-definition FPD or the like to manufacture a suitable mask.

In the mask blank of the present invention, in the light shielding layer in contact with the antireflection layer, the film thickness up to the etching rate reducing layer is set to λ*20/405 or more with respect to the wavelength λ.
By satisfying such optical specifications, it is possible to provide a mask blank that can be used for manufacturing a high-definition FPD or the like to manufacture a suitable mask.

In the mask blank of the present invention, the thickness of the antireflection layer is within the range of λ*25/405 to λ*30/405 or λ*95/405 to λ*100/405 with respect to the wavelength λ. Is set.
By satisfying such optical specifications, it is possible to provide a mask blank that can be used for manufacturing a high-definition FPD or the like to manufacture a suitable mask.

The mask of the present invention is manufactured using the mask blank described in any of the above.
By satisfying such optical specifications, it is possible to provide a mask suitable for use in high-definition FPD manufacturing and the like.

According to the present invention, it is possible to provide an effect that it is possible to provide a mask blank that satisfies the required optical specifications and does not cause a deterioration in shape during pattern formation.

It is sectional drawing which shows 1st Embodiment of the mask blanks which concern on this invention. It is sectional drawing which shows 1st Embodiment of the mask which concerns on this invention. It is a schematic diagram which shows the film-forming apparatus which manufactures 1st Embodiment of the mask blanks which concerns on this invention. It is a schematic diagram which shows the film-forming apparatus which manufactures 1st Embodiment of the mask blanks which concerns on this invention. It is a graph which shows the relationship between the light-shielding layer (low oxygen concentration Cr film) thickness and reflectance in 1st Embodiment of the mask blanks which concern on this invention. It is a graph which shows the relationship between the antireflection layer (high oxygen concentration Cr film) thickness and reflectance in 1st Embodiment of the mask blanks which concern on this invention. It is sectional drawing which shows 2nd Embodiment of the mask blanks which concern on this invention. It is sectional drawing which shows 3rd Embodiment of the mask blanks which concern on this invention. It is sectional drawing which shows 4th Embodiment of the mask blanks which concern on this invention. It is sectional drawing which shows 5th Embodiment of the mask blanks which concern on this invention. It is sectional drawing which shows 6th Embodiment of the mask blanks which concern on this invention. It is sectional drawing which shows the example of the mask in which the light shielding layer was formed as one layer. It is sectional drawing which shows the example of the mask in which the light shielding layer was formed as one layer. 4 is an image showing an experimental example of a mask according to the present invention. 4 is an image showing an experimental example of a mask according to the present invention. 4 is an image showing an experimental example of a mask according to the present invention. It is a graph which shows the composition in the thickness direction as an experimental example of the mask blanks and mask which concern on this invention. It is a graph which shows the composition in the thickness direction as an experimental example of the mask blanks and mask which concern on this invention. It is a graph which shows the composition in the thickness direction as an experimental example of the mask blanks and mask which concern on this invention.

Hereinafter, a first embodiment of a mask blank and a mask according to the present invention will be described with reference to the drawings.
FIG. 1 is a perspective view showing a mask blank in the present embodiment, and in the drawing, reference symbol MB is a mask blank.

The mask blanks MB according to the present embodiment are used, for example, for a mask used in a wavelength range of exposure light of 365 nm to 436 nm. As shown in FIG. 1, the mask blanks MB according to the present embodiment are formed on a transparent substrate (glass substrate) S, a light shielding layer 11B formed on the transparent substrate S, and a light shielding layer 11B. The etching rate reducing layer 12, the light shielding layer 11A formed on the etching rate reducing layer 12, and the antireflection layer 13 formed on the light shielding layer 11A.
That is, in the mask blank MB according to this embodiment, the light shielding layers 11A and 11B are divided in the thickness direction by the etching rate reducing layer 12.

As the transparent substrate S, a material having excellent transparency and optical isotropy is used, and for example, a quartz glass substrate can be used. The size of the transparent substrate S is not particularly limited, and it depends on the substrate (eg, FPD substrate such as LCD (liquid crystal display), plasma display, organic EL (electroluminescence) display, or semiconductor substrate) that is exposed using the mask. It is selected appropriately. The present embodiment can be applied to a substrate having a diameter of about 100 mm, a rectangular substrate having a side of about 50 to 100 mm and a side of 300 mm or more, and further, a quartz substrate having a length of 450 mm, a width of 550 mm, and a thickness of 8 mm, and a maximum side dimension. A substrate having a thickness of 1000 mm or more and a thickness of 10 mm or more can also be used.

Further, the flatness of the transparent substrate S may be reduced by polishing the surface of the transparent substrate S. The flatness of the transparent substrate S can be, for example, 20 μm or less. As a result, the depth of focus of the mask becomes deep, and it becomes possible to greatly contribute to the formation of a fine and highly accurate pattern. Further, the flatness is preferably as small as 10 μm or less.

The light-shielding layer 11A and the light-shielding layer 11B contain Cr (chromium) as a main component, and specifically, Cr alone, and oxides, nitrides, carbides, oxynitrides, carbonitrides, and oxides of Cr. It may be composed of one selected from carbonitrides, or may be composed of two or more selected from these layers.
The light-shielding layer 11A and the light-shielding layer 11B contain Cr (chromium) and can contain O (oxygen) and/or C (carbon). Further, the light shielding layers 11A and 11B can contain N (nitrogen).

The light-shielding layer 11A and the light-shielding layer 11B have almost the same composition, but may have a slightly different composition as long as the optical characteristics described later are satisfied.

Specifically, in the light shielding layers 11A and 11B, the oxygen concentration is changed in the film thickness direction to increase the oxygen concentration from the glass substrate S side toward the antireflection layer 13 side. That is, the oxygen concentration of the light shielding layer 11A is set to be higher than the oxygen concentration of the light shielding layer 11B.

Further, in the light shielding layers 11A and 11B, the carbon concentration is changed in the film thickness direction to increase the carbon concentration from the glass substrate S side toward the antireflection layer 13 side. That is, the carbon concentration of the light shielding layer 11A is set higher than the carbon concentration of the light shielding layer 11B.

The light shielding layers 11A and 11B are formed by using a chromenium film containing oxygen, nitrogen and carbon. At this time, in order to increase the optical density, the total film thickness of the light shielding layer 11A and the light shielding layer 11B is preferably 100 nm or more.

The antireflection layer 13 contains Cr (chromium) similarly to the light shielding layers 11A and 11B in the thickness direction. Further, the antireflection layer 13 is a chromium oxide film containing O (oxygen). Further, the antireflection layer 13 can contain C (carbon) and/or N (nitrogen). The film thickness of the antireflection layer 13 is set by the exposure wavelength (wavelength region is 365 to 436 nm) when used as a mask in the exposure step, and the required optical density, reflectance, etc. defined by the exposure wavelength.

As the antireflection layer 13, the reflectance can be reduced by increasing the difference between the refractive index of the antireflection layer 13 and the refractive index of the light shielding layer 11A.
For this reason, it is desirable that the chromenium film containing oxygen, nitrogen and carbon used as the antireflection layer 13 has a refractive index of 2.5 or less and an extinction coefficient of 1.0 or less at a wavelength of 365 to 436 nm.

Alternatively, the antireflection layer 13 can be set to have a thickness greater than about 25 nm. Further, the thickness of the antireflection layer 13 is preferably 15 to 40 nm.

At the same time, in order to set the reflectance of the antireflection layer 13 to less than about 5%, it is necessary that the oxygen content rate be within a predetermined range. Specifically, the oxygen content is set to be about 30 atm% or higher. Further, the oxygen concentration contained in the chromium film used as the antireflection layer 13 is preferably 50% or more.

The etching rate reduction layer 12 contains Cr (chromium) similarly to the light shielding layers 11A and 11B in the thickness direction. Further, the antireflection layer 13 is a chromium oxide film containing O (oxygen) so as to have a lower etching rate than the light shielding layers 11A and 11B. Further, the antireflection layer 13 can contain C (carbon) and/or N (nitrogen). The etching rate reduction layer 12 has an oxygen concentration and a carbon concentration set so as to have the same etching rate as the antireflection layer 13 or a slightly lower etching rate than the antireflection layer 13. ..

The etching rate reduction layer 12 may be the same film as the antireflection layer 13. That is, the etching rate reduction layer 12 can be a chromium film containing oxygen, nitrogen and carbon.

The etching rate reducing layer 12 is arranged at the center position of the interface between the transparent substrate S and the light shielding layer 11A and the interface between the light shielding layer 11B and the antireflection layer 13 in the thickness direction.

The mask blanks MB of this embodiment can be applied, for example, when manufacturing a mask (photomask) M that is a patterning mask for a glass substrate for FPD.

The mask blanks MB of this embodiment are set so that the reflectance is smaller than 5% and the value of the optical density OD is higher than 5. This makes it possible to prevent complex reflection when manufacturing the mask (photomask) M, and at the same time, to manufacture a high-definition mask that satisfies necessary optical specifications (optical characteristics).
The mask blanks MB of this embodiment satisfy the above optical specifications (optical characteristics), and other characteristics are not limited as long as they maintain the etching characteristics described later.

FIG. 2 is a cross-sectional view showing a mask manufactured from the mask blanks in this embodiment.
As shown in FIG. 2, the mask (photomask) M of the present embodiment has a mask blanks MB in which exposed regions of a glass substrate (transparent substrate) S, a light-shielding pattern 11Aa formed by patterning a light-shielding layer 11A, and a light-shielding pattern 11Aa. The etching rate reduction pattern 12a patterned from the etching rate reduction layer 12, the light blocking pattern 11Ba patterned from the light blocking layer 11B, and the antireflection pattern 13a patterned from the antireflection layer 13 are the glass substrate (transparent substrate) S. And a light-shielding region laminated on the.

In the mask (photomask) M, the light-shielding region is a region which can block the irradiation light (exposure light) by the light-shielding patterns 11Aa and 11Ba in the exposure process.

According to the mask (photomask) M of the present embodiment, in exposure processing, a composite wavelength including light in a wavelength region, particularly g-line (436 nm), h-line (405 nm), and i-line (365 nm) is used as exposure light. be able to. This allows exposure and development to be performed to control the shape of the organic resin to form spacers and openings having appropriate shapes. Further, the pattern accuracy is significantly improved, and it becomes possible to form a fine and highly accurate pattern.

According to this mask (photomask) M, it is possible to improve the pattern accuracy by using the exposure light in the above wavelength range, and it is possible to form a fine and highly accurate pattern. As a result, a high-definition/high-quality flat panel display or the like can be manufactured.

Hereinafter, a method for manufacturing the mask blanks MB of this embodiment will be described.

The mask blanks MB in this embodiment are manufactured by the manufacturing apparatus shown in FIG. 3 or 4.

A manufacturing apparatus S10 shown in FIG. 3 is an interback type sputtering apparatus, and is a load/unload chamber S11 and a film forming chamber (vacuum processing chamber) connected to the load/unload chamber S11 via a sealing means S13. S12 and.

In the loading/unloading chamber S11, a transporting means S11a for transporting the glass substrate S loaded from the outside to the film forming chamber S12 or for transporting the film forming chamber S12 to the outside, and a rotary for roughing the inside of the chamber. Exhaust means S11b such as a pump is provided.

In the film forming chamber S12, a substrate holding means S12a, a cathode electrode (backing plate) S12c having a target S12b as a means for supplying a film forming material, a power source S12d for applying a negative potential sputtering voltage to the backing plate S12c. A gas introducing means S12e for introducing gas into this chamber and a high vacuum evacuation means S12f such as a turbo molecular pump for drawing a high vacuum inside the film forming chamber S12 are provided.

The substrate holding means S12a receives the glass substrate S transferred by the transfer means S11a, holds the glass substrate S so as to face the target S12b during film formation, and also transfers the glass substrate S from the load/unload chamber S11. Can be carried in and carried out to the load/unload chamber S11.
The target S12b is made of a material having a composition necessary for forming a film on the glass substrate S.

In the manufacturing apparatus S10 shown in FIG. 3, the glass substrate S carried in from the load/unload chamber S11 is subjected to sputtering film formation in the film forming chamber (vacuum processing chamber) S12, and then the load/unload chamber S11. The glass substrate S on which the film formation has been completed is carried out.

In the film forming step, the sputtering gas and the reactive gas are supplied from the gas introducing means S12e to the film forming chamber S12, and the sputtering voltage is applied to the backing plate (cathode electrode) S12c from the external power source. Also, a predetermined magnetic field may be formed on the target S12b by a magnetron magnetic circuit. The ions of the sputtering gas excited by the plasma in the film forming chamber S12 collide with the target S12b of the cathode electrode S12c to cause the particles of the film forming material to fly out. Then, after the particles that have jumped out and the reaction gas are combined, they are attached to the glass substrate S, whereby a predetermined film is formed on the surface of the glass substrate S.

At this time, the film formation of the light shielding layer 11B, the film formation of the etching rate reduction layer 12, the film formation of the light shielding layer 11A, and the film formation of the antireflection layer 13 should be replaced with the target S12b having the necessary composition. You can

At this time, in the film formation of the light shielding layer 11b, the film formation of the etching rate reduction layer 12, the film formation of the light shielding layer 11A, and the film formation of the antireflection layer 13, different amounts of oxygen are included from the gas introduction unit S12e. A necessary film forming gas such as a gas or a carbon-containing gas is supplied, and the partial pressure is switched so as to be controlled so that the composition is within the set range.

Alternatively, in the manufacture of the mask blank MB of the present embodiment, in the film formation of the light shielding layer 11B, the film formation of the etching rate reduction layer 12, the film formation of the light shielding layer 11A, and the film formation of the antireflection layer 13, the target is formed. It is also possible not to replace S12b.

Further, in addition to the film formation of the light shielding layer 11B, the film formation of the etching rate reducing layer 12, the film formation of the light shielding layer 11A, and the film formation of the antireflection layer 13, another film may be laminated. In this case, the mask blank MB of the present embodiment is manufactured by forming a film by sputtering under the sputtering conditions of a corresponding target, gas or the like or by stacking the corresponding films by another film forming method.

The manufacturing apparatus S20 shown in FIG. 4 is an in-line type sputtering apparatus, and includes a load chamber S21, a film forming chamber (vacuum processing chamber) S22 connected to the load chamber S21 via a sealing means S23, and film forming. An unload chamber S25 connected to the chamber S22 via a sealing means S24.

The loading chamber S21 is provided with a transporting means S21a for transporting the glass substrate S loaded from the outside to the film forming chamber S22, and an exhausting means S21b such as a rotary pump for roughing the inside of the chamber.

In the film forming chamber S22, a substrate holding means S22a, a cathode electrode (backing plate) S22c having a target S22b as a means for supplying a film forming material, and a power source S22d for applying a negative potential sputtering voltage to the backing plate S22c. A gas introducing means S22e for introducing gas into this chamber and a high vacuum evacuation means S22f such as a turbo molecular pump for drawing a high vacuum inside the film forming chamber S22 are provided.

The substrate holding means S22a receives the glass substrate S carried by the carrying means S21a, holds the glass substrate S so as to face the target S22b during film formation, and carries the glass substrate S from the load chamber S21. It can be carried out to the unload chamber S25.
The target S22b is made of a material having a composition necessary for forming a film on the glass substrate S.

The unloading chamber S25 is provided with a transporting means S25a for transporting the glass substrate S carried in from the film forming chamber S22 to the outside, and an exhausting means S25b such as a rotary pump for roughing the interior of the chamber.

In the manufacturing apparatus S20 shown in FIG. 4, the glass substrate S carried in from the load chamber S21 is subjected to sputtering film formation in the film formation chamber (vacuum processing chamber) S22, and then the film formation is completed from the unload chamber S25. The glass substrate S is carried out.

In the film forming step, the sputtering gas and the reactive gas are supplied from the gas introducing means S22e to the film forming chamber S22, and the sputtering voltage is applied to the backing plate (cathode electrode) S22c from the external power source. Also, a predetermined magnetic field may be formed on the target S22b by a magnetron magnetic circuit. The ions of the sputtering gas excited by the plasma in the film forming chamber S22 collide with the target S22b of the cathode electrode S22c to cause the particles of the film forming material to fly out. Then, after the particles that have jumped out and the reaction gas are combined, they are attached to the glass substrate S, whereby a predetermined film is formed on the surface of the glass substrate S.

At this time, the film formation of the light shielding layer 11B, the film formation of the etching rate reduction layer 12, the film formation of the light shielding layer 11A, and the film formation of the antireflection layer 13 should be replaced with the target S22b having the necessary composition. You can

At this time, in the film formation of the light shielding layer 11B, the film formation of the etching rate reduction layer 12, the film formation of the light shielding layer 11A, and the film formation of the antireflection layer 13, different amounts of oxygen are included from the gas introduction unit S12e. A necessary film forming gas such as a gas or a carbon-containing gas is supplied, and the partial pressure is switched so as to be controlled so that the composition is within the set range.

Alternatively, in the manufacture of the mask blank MB of the present embodiment, in the film formation of the light shielding layer 11B, the film formation of the etching rate reduction layer 12, the film formation of the light shielding layer 11A, and the film formation of the antireflection layer 13, the target is formed. It is also possible not to replace S22b.

Further, in addition to the film formation of the light shielding layer 11B, the film formation of the etching rate reducing layer 12, the film formation of the light shielding layer 11A, and the film formation of the antireflection layer 13, when another film is laminated, The mask blank MB of the present embodiment is manufactured by forming a film by sputtering as a sputtering condition of a corresponding target, gas or the like or by stacking the corresponding film by another film forming method.

In the manufacturing apparatus S10 or the manufacturing apparatus S20 described above, first, on the glass substrate S, a light shielding layer 11B containing Cr as a main component, an etching rate reducing layer 12 containing Cr as a main component, and the like are formed by using a DC sputtering method or the like. The light shielding layer 11A containing Cr as a main component and the antireflection layer 13 containing Cr as a main component are sequentially formed.
At this time, as film forming conditions, DC sputtering using chromium as a target can be performed in a state where argon, nitrogen (N ₂ ) or the like is contained as a sputtering gas.

In the film formation of the light shielding layer 11B, the target S12b or the target S22b containing Cr as a main component is used, a gas atmosphere containing oxygen and carbon (film forming atmosphere) is obtained, and the optical specifications (optical characteristics) described above are obtained. Thus, the oxygen concentration and the carbon concentration in the atmosphere gas are set. Specifically, the gas flow rates of the oxygen-containing gas and the carbon-containing gas are set so that the optical density OD value and reflectance of the mask blank MB described above are realized.

In the film formation of the etching rate reducing layer 12, a target S12b or a target S22b containing Cr as a main component is used, a gas atmosphere containing oxygen and carbon (film forming atmosphere) is provided, and the optical specifications (optical characteristics) described above are used. The oxygen concentration and carbon concentration in the atmosphere gas are set so that Specifically, the gas flow rates of the oxygen-containing gas and the carbon-containing gas are set so as to realize the etching rate described later.
Here, examples of the carbon-containing gas include CO ₂ (carbon dioxide), CH ₄ (methane), C ₂ H ₆ (ethane), CO (carbon monoxide), and the like. Examples of the oxygen-containing gas include CO ₂ (carbon dioxide), O ₂ (oxygen), N ₂ O (dinitrogen monoxide), NO (nitrogen monoxide), and the like.

At this time, during the film formation of the light-shielding layer 11B and the etching rate reduction layer 12, the film formation is temporarily interrupted or intermittently formed, and the oxygen concentration and the carbon concentration are switched to form a low oxygen concentration region. It is possible to form an interface between the light-shielding layer 11B that becomes a high-oxygen region and the etching rate reducing layer 12 that becomes a high oxygen region.

Alternatively, the light-shielding layer 11B and the etching rate reduction layer 12 are continuously formed, and the oxygen concentration and the carbon concentration are changed so as to be gradually increased to change the light-shielding layer 11B, which is a low oxygen region, from the high oxygen region. It is possible to form the etching rate reducing layer 12 having a gradient concentration.

In forming the light-shielding layer 11B and the etching rate reducing layer 12, the target S12b or the target S22b having a necessary composition is used according to the optical characteristics required for each layer, and the type and the composition of the atmosphere gas are changed. It is preferable to select the membrane conditions.

In the film formation of the light shielding layer 11A, the target S12b or the target S22b containing Cr as a main component is used, a gas atmosphere (film forming atmosphere) containing oxygen and carbon is used, and the above-mentioned optical specifications (optical characteristics) are used. ), the oxygen concentration and carbon concentration in the atmosphere gas are set. Specifically, the gas flow rates of the oxygen-containing gas and the carbon-containing gas are set so that the optical density OD value and reflectance of the mask blank MB described above are realized.

At this time, the film formation can be temporarily suspended between the film formation of the etching rate reduction layer 12 and the light shielding layer 11A. Alternatively, the oxygen concentration and the carbon concentration can be switched while the film is formed intermittently between the film formation of the etching rate reduction layer 12 and the light shielding layer 11A. This makes it possible to form an interface between the etching rate reducing layer 12 which becomes the high oxygen region and the light shielding layer 11A which becomes the low oxygen concentration region.

Alternatively, the etching rate reducing layer 12 and the light-shielding layer 11A are continuously formed, and the oxygen concentration and the carbon concentration are changed so as to be gradually reduced, so that the etching rate reducing layer 12 in the high oxygen region is lowered. The light shielding layer 11A, which is an oxygen region, can be formed to have a gradient concentration.

In forming the etching rate reducing layer 12 and the light shielding layer 11A, a target S12b or a target S22b having a necessary composition is used according to the optical characteristics required for each layer, and the type and the composition of the atmosphere gas are changed. It is preferable to select the membrane conditions.

Further, in the film formation of the antireflection layer 13, the target S12b or the target S22b containing Cr as a main component is used, a gas atmosphere (film forming atmosphere) containing oxygen and carbon is used, and the above-mentioned optical specifications (optical Characteristics), the oxygen concentration and the carbon concentration in the atmosphere gas are set. Specifically, the gas flow rates of the oxygen-containing gas and the carbon-containing gas are set so that the optical density OD value and reflectance of the mask blank MB described above are realized.

At this time, during the film formation of the light-shielding layer 11A and the antireflection layer 13, the film formation is temporarily interrupted or intermittently formed, and the oxygen concentration and the carbon concentration are switched to set the low oxygen concentration region. It is possible to form an interface between the light shielding layer 11</b>A and the antireflection layer 13 that is a high oxygen region.

Hereinafter, a method of manufacturing the mask M from the mask blanks MB of this embodiment manufactured in this way will be described.

As shown in FIG. 1, the mask blanks MB has a light shielding layer 11B, an etching rate reducing layer 12, a light shielding layer 11A, and an antireflection layer 13 formed on the entire surface thereof.

Next, a photoresist layer is formed on the antireflection layer 13 which is the uppermost layer of the mask blank MB.
The photoresist layer may be positive or negative, but may be positive, for example. A liquid resist is used as the photoresist layer.

Subsequently, the photoresist layer is exposed and developed to form a resist pattern on the antireflection layer 13. The resist pattern functions as an etching mask for the antireflection layer 13, the light shielding layer 11A, the etching rate reducing layer 12, and the light shielding layer 11B, and removes the antireflection layer 13, the light shielding layer 11A, the etching rate reducing layer 12, and the light shielding layer 11B. The shape is appropriately determined according to the etching pattern of the transmissive region.
As an example, the resist pattern is set to have a shape having an opening width corresponding to the opening width dimension of the light shielding pattern 11Ba, the etching rate reducing pattern 12a, the light shielding pattern 11Aa, and the antireflection pattern 13a to be formed in the transmissive region.

Next, the step of wet-etching the antireflection layer 13, the light shielding layer 11A, the etching rate reducing layer 12, and the light shielding layer 11B with a predetermined etching solution (etchant) over the resist pattern is started.

As the etching liquid, an etching liquid containing cerium diammonium nitrate corresponding to the antireflection layer 13, the light-shielding layer 11A, the etching rate reducing layer 12, and the light-shielding layer 11B each containing Cr can be used. For example, it is preferable to use cerium secondary ammonium nitrate containing an acid such as nitric acid or perchloric acid as the etching liquid.

Here, the wet etching proceeds from the front surface side (upper side or outer side) of the mask blank in the opening portion of the resist pattern which becomes the transmissive region.

That is, first, the antireflection layer 13 is wet-etched. Next, the light-shielding layer 11A, the etching rate reduction layer 12, and the light-shielding layer 11B are wet-etched in the reverse order of the stacked order.
Therefore, while the etching of the layer at a position lower than the layer itself (close to the glass substrate S) progresses, the etching solution comes into contact with the layer and the etching progresses.

Here, the antireflection layer 13 and the etching rate reduction layer 12 are in a state where the oxygen concentration and the carbon concentration are high and the etching rate is low, whereas the light shielding layer 11B and the light shielding layer 11A have a low oxygen concentration and the carbon concentration. The etching rate is high.

In particular, the light shielding layer 11A is located far from the glass substrate S with respect to the etching rate reducing layer 12 and the light shielding layer 11B. That is, the etching rate reduction layer 12 and the light shielding layer 11B are located on the lower side (closer to the glass substrate S) than the light shielding layer 11A.
Therefore, even after the etching of the light shielding layer 11A in the thickness direction is completed and the etching proceeds to a predetermined width dimension, the etching of the etching rate reduction layer 12 and the light shielding layer 11B proceeds. Therefore, while the etching rate reduction layer 12 and the light shielding layer 11B are being etched, the light shielding layer 11A is brought into contact with the etching liquid and the etching proceeds.

Even in this state, the etching amount in the width direction, that is, the etching amount in the depth direction indicated by the arrow ss in FIG. 2 does not exceed the predetermined value. The composition ratio and the film thickness are set.

Specifically, the etching rate reduction layer 12 has a higher oxygen concentration and carbon concentration and a lower etching rate than the light shielding layers 11A and 11B, and near the interface between the light shielding layer 11A and the etching rate reduction layer 12, The light-shielding layer 11A can suppress the etching amount in the depth direction ss.

FIG. 12 is a cross-sectional view showing an example of a mask in which the light shielding layer is formed as a single layer.
Here, consider the case where the light shielding layer 11 is formed as a single layer as shown in FIG. The etching rate reduction layer 12 is not provided. The thickness of the light shielding layer 11 is set equal to the total thickness of the light shielding layers 11A and 11B. The film thickness and composition are set so that the optical specifications (optical characteristics) of the mask are equivalent to those of the mask blanks MB shown in FIG. 1 or the mask M shown in FIG.

In this case, as shown in FIG. 12, in the one-layer light shielding layer 11, when wet-etched, the side surface portion of the transmissive region is excessively etched in the depth direction ss, and thus the side surface portion of the light shielding layer 11 is not etched. The recess X is formed and formed. This state is the state in which the pattern shape has deteriorated.

On the other hand, in the mask blanks MB or the mask M of the present embodiment, the etching rate reduction layer 12 has a higher oxygen concentration and carbon concentration and a lower etching rate than the light shielding layers 11A and 11B, that is, antireflection. The layer 13 is set to have a substantially same etching rate as the layer 13. As a result, the etching amount of the etching rate reducing layer 12 in the depth direction ss becomes substantially the same as the etching amount of the antireflection layer 13 at the central position in the total thickness of the light shielding layers 11A and 11B.

Further, the light shielding layers 11A and 11B are divided in the thickness direction, and the etching rate reducing layer 12 is provided between the light shielding layers 11A and 11B, so that the light shielding layer 11A is etched in the depth direction ss. The amount can be suppressed.
Similarly, in the vicinity of the interface between the etching rate reduction layer 12 and the light shielding layer 11B, the light shielding layer 11B can suppress the etching amount in the depth direction ss.

At the same time, as compared with the case of the one-layer light shielding layer 11 shown in FIG. 12, the light shielding layers 11A and 11B are divided in the thickness direction, and the etching rate reducing layer 12 is provided between these light shielding layers 11A and 11B. By being provided, the size of the light shielding layer 11A and the light shielding layer 11B in the thickness direction is reduced. Thereby, the etching amount in the depth direction ss in the light shielding layer 11A and the light shielding layer 11B can be suppressed respectively.

In particular, the light-shielding layer 11A is set to have a smaller dimension in the thickness direction, is set to have a slightly higher oxygen concentration and carbon concentration than the light-shielding layer 11B, and is set to have a slightly lower etching rate than the light-shielding layer 11B. .. As a result, the amount of etching in the depth direction ss can be suppressed in the light shielding layer 11A, which is exposed to the etching liquid for a longer time than the light shielding layer 11B. That is, the size of the recess X in the depth direction ss of the light shielding layer 11A and the size of the recess X in the depth direction ss of the light shielding layer 11B can be set to substantially the same value. This can reduce the difference in shape between the light-shielding layers 11A and 11B in the thickness direction.

As a result, as shown in FIG. 12, as compared with the case where the light-shielding layers 11A and 11B are continuous with a total film thickness, the influence of the recess X formed in the depth direction ss is reduced, and the light transmission layer in the transmission region is reduced. The side surface of the pattern can be formed in a shape close to vertical.

Then, after the etching solution is washed to complete the wet etching, the resist pattern is removed. A well-known resist stripping solution can be used for removing the resist pattern, and thus detailed description thereof is omitted here.
As described above, the mask M of this embodiment can be manufactured.

As described above, in the mask M manufactured from the mask blanks MB according to this embodiment, the recesses X in the light shielding layers 11A and 11B are formed to be large in a state where the desired optical specifications (optical characteristics) are satisfied. Absent.

In particular, by providing the high oxygen concentration etching rate reducing layer 12 between the light shielding layer 11A and the light shielding layer 11B, it is possible to suppress the protruding shape in the direction SS near the interface between the etching rate reducing layer 12 and the light shielding layer 11A. It becomes possible to do. Similarly, the high oxygen concentration etching rate reducing layer 12 makes it possible to suppress the protruding shape toward the direction SS in the vicinity of the interface between the etching rate reducing layer 12 and the light shielding layer 11B.

Further, since the light-shielding layer 11A and the light-shielding layer 11B are divided by the etching rate reducing layer 12, the film thickness dimension of the light-shielding layer 11A and the light-shielding layer 11B can be reduced, and the protruding shape toward the depth direction ss can be suppressed. It becomes possible to do.
As a result, excessive etching of the light shielding layers 11A and 11B can be suppressed. Therefore, it is possible to prevent the shapes of the patterns 13a, 11Aa, 12a, 11Ba from deviating from the desired states.

Further, by changing the carbon concentration of the light shielding layers 11A and 11B in the film thickness direction to increase the carbon concentration from the glass substrate S side toward the antireflection layer 13 side, the cross-sectional shape of the pattern is further improved. Is possible.
This makes it possible to provide a mask M suitable for use in high-definition FPD manufacturing.

In particular, in the mask blanks MB according to the present embodiment, it is possible to maintain and realize low reflectance and high optical density as the optical specifications (optical characteristics) of the mask M.
Moreover, in order to maintain these optical specifications (optical characteristics) and the pattern shape, the mask blanks MB and the mask M described above can be realized simply by setting the gas flow rate.

Further, in the mask M according to the present embodiment, the optical density OD value is 5.0 or more and the reflectance is 5 as compared with the case where a composite wavelength composed of i-line, h-line and g-line is used as the wavelength of exposure light. The value of less than or equal to% can be maintained.
Further, in the mask M according to the present embodiment, the state of the optical density OD of 5.0 or more and the reflectance of 5% or less is maintained in comparison with the case where the wavelength of 436 nm is used as the exposure light. be able to.

Here, in the mask M according to the present embodiment, the above-mentioned optical specifications (optical characteristics) are maintained in a part of the range of the wavelength of the exposure light applied. Preferably, the above optical specifications (optical characteristics) are maintained with respect to the exposure light corresponding to the middle h-line in the range of the wavelength of the adapted exposure light.
Alternatively, the optical density and reflectance values can be adjusted as needed.

In the antireflection layer 13, the light shielding layer 11A, the etching rate reducing layer 12, and the light shielding layer 11B of the mask blank MB according to the present embodiment, the optical specifications (optical characteristics for transmitted light having a wavelength of 405 nm during the exposure process using the mask M). ) Can be set within the above range.

FIG. 5 is a graph showing the relationship between the light-shielding layer (low oxygen concentration Cr film) thickness and the reflectance in the mask blank of this embodiment. FIG. 6 is a graph showing the relationship between the antireflection layer (high oxygen concentration Cr film) thickness and the reflectance in the mask blank according to this embodiment.
Here, the reflectance of the mask blank MB of this embodiment varies depending on the thickness of the light shielding layer 11A, as shown in FIG. Therefore, in order to realize a low reflectance of about 5% or less, it is necessary to set the thickness of the light shielding layer 11A to 20 nm or more. Here, the measurement wavelength of the reflectance in FIG. 5 is 405 nm.

Here, it is desirable that the thickness of the etching rate reducing layer 12 be appropriately changed with respect to the thicknesses of the light shielding layers 11A and 11B depending on the wavelength of light used during exposure. As a result, the influence of the interference effect of light used for exposure can be reduced.

Further, the reflectance of the mask blank MB of this embodiment varies depending on the thickness of the antireflection layer 13, as shown in FIG. Therefore, in order to realize a low reflectance of about 5% or less, it is necessary to define the thickness of the antireflection layer 13. The film thickness of the light shielding layer 11A in FIG. 6 is 50 nm, and the reflectance measurement wavelength is 405 nm. Therefore, in order to realize a low reflectance of about 5% or less, it is necessary to set the thickness of the antireflection layer 13 to be around 27 nm.

Further, the composition of the etching rate reducing layer 12 in the mask blanks MB of the present embodiment preferably has an oxygen concentration of 20% or more and a carbon concentration of 30% or more so that the etching rate is close to that of the antireflection layer 13. ..

A second embodiment of a mask blank and a mask according to the present invention will be described below with reference to the drawings.
FIG. 7 is a cross-sectional view showing a mask blank in the present embodiment. In the present embodiment, what is different from the first embodiment described above is the number of etching rate reducing layers, and the other points described above. The components corresponding to those in the first embodiment are designated by the same reference numerals and the description thereof will be omitted.

As shown in FIG. 7, the mask blanks MB according to the present embodiment are formed on a transparent substrate (glass substrate) S, a light shielding layer 11C formed on the transparent substrate S, and a light shielding layer 11C. The etching rate reducing layer 12B, the light shielding layer 11B formed on the etching rate reducing layer 12B, the etching rate reducing layer 12A formed on the light shielding layer 11B, and the etching rate reducing layer 12A. The light shielding layer 11A and the antireflection layer 13 formed on the light shielding layer 11A are included.
That is, in the mask blank MB according to the present embodiment, the light shielding layers 11A, 11B and 11C are divided into three in the thickness direction by the etching rate reducing layers 12A and 12B.

The light-shielding layer 11A, the light-shielding layer 11B, and the light-shielding layer 11C have almost the same composition, but may have a slightly different composition as long as the optical characteristics described later are satisfied.

Specifically, in the light-shielding layer 11A, the light-shielding layer 11B, and the light-shielding layer 11C, the oxygen concentration is changed in the film thickness direction to increase the oxygen concentration from the glass substrate S side toward the antireflection layer 13 side. That is, the oxygen concentration of the light shielding layer 11B is set higher than the oxygen concentration of the light shielding layer 11C, and the oxygen concentration of the light shielding layer 11A is set higher than the oxygen concentration of the light shielding layer 11B.

Further, in the light shielding layer 11A, the light shielding layer 11B, and the light shielding layer 11C, the carbon concentration is changed in the film thickness direction to increase the carbon concentration from the glass substrate S side toward the antireflection layer 13 side. That is, the carbon concentration of the light shielding layer 11B is set higher than the carbon concentration of the light shielding layer 11C, and the carbon concentration of the light shielding layer 11A is set higher than the carbon concentration of the light shielding layer 11B.

The light-shielding layer 11A, the light-shielding layer 11B, and the light-shielding layer 11C are formed by using a chromenium film containing oxygen, nitrogen, and carbon. At this time, in order to increase the optical density, the total thickness of the light shielding layer 11A, the light shielding layer 11B, and the light shielding layer 11C is preferably 100 nm or more.

Both the etching rate reducing layer 12A and the etching rate reducing layer 12B can be the same films as the antireflection layer 13. That is, the etching rate reducing layers 12A and 12B can be formed as a chromenium film containing oxygen, nitrogen and carbon.

The etching rate reducing layer 12A and the etching rate reducing layer 12B are one third in the thickness direction with respect to the interface between the transparent substrate S and the light shielding layer 11A and the interface between the light shielding layer 11C and the antireflection layer 13. It is arranged in each position.

The etching rate reducing layer 12A and the etching rate reducing layer 12B may have the same thickness.
Alternatively, the etching rate reduction layer 12A and the etching rate reduction layer 12B can be changed in the thickness direction in the thickness direction to increase the thickness from the antireflection layer 13 side toward the glass substrate S side. ..

As in the first embodiment, the mask blanks MB of the present embodiment are set so that the reflectance is smaller than 5% and the optical density OD is higher than 5. This makes it possible to prevent complex reflection when manufacturing the mask (photomask) M, and at the same time, to manufacture a high-definition mask that satisfies necessary optical specifications (optical characteristics).
The mask blanks MB of the present embodiment satisfy the above optical specifications (optical characteristics) as in the case of the first embodiment, and other characteristics are not limited as long as the etching characteristics described below are maintained. ..

In order to satisfy the above reflectance, the light shielding layer 11A and the antireflection layer 13 need to have the same film thickness and composition as those in the first embodiment.

Also in the present embodiment, the mask M manufactured from the mask blanks MB does not have large recesses X in the light shielding layers 11A to 11C in a state where the desired optical specifications (optical characteristics) are satisfied. In particular, by providing the high oxygen concentration etching rate reducing layers 12A and 12B between the light shielding layers 11A to 11C, it is possible to suppress the protruding shape in the direction SS in the vicinity of the interface between the antireflection layer 13 and the light shielding layer 11A. Will be possible. As a result, excessive etching of the light shielding layers 11A and 11B can be suppressed. Therefore, it is possible to prevent the shapes of the patterns 13a, 11Aa, 12a, 11Ba from deviating from the desired states.

As described above, in the mask M manufactured from the mask blanks MB according to the present embodiment, the recesses X in the light shielding layers 11A to 11C are formed to be large in a state where the desired optical specifications (optical characteristics) are satisfied. Absent.

In particular, by providing the high oxygen concentration etching rate reducing layers 12A and 12B between the light shielding layers 11A to 11C, the protruding shape in the direction SS near the interface between the etching rate reducing layer 12A and the light shielding layer 11A is suppressed. It will be possible. Similarly, the high oxygen concentration etching rate reducing layer 12A makes it possible to suppress the protruding shape toward the direction SS in the vicinity of the interface between the etching rate reducing layer 12A and the light shielding layer 11B.

Similarly, the high oxygen concentration etching rate reducing layer 12B makes it possible to suppress the protruding shape in the direction SS in the vicinity of the interface between the etching rate reducing layer 12B and the light shielding layer 11B. Similarly, the high oxygen concentration etching rate reducing layer 12B makes it possible to suppress the protruding shape in the direction SS in the vicinity of the interface between the etching rate reducing layer 12B and the light shielding layer 11C.

Further, since the light-shielding layers 11A to 11C are divided by the etching rate reducing layers 12A and 12B, the thickness of each of the light-shielding layers 11A to 11C can be further reduced, and the protruding shape toward the depth direction ss can be suppressed. It becomes possible to do.
As a result, excessive etching of the light shielding layers 11A to 11C can be further suppressed. Therefore, the deterioration of the pattern shape can be further prevented.

Furthermore, the cross-sectional shape of the pattern can be further improved by changing the carbon concentration of the light shielding layers 11A to 11C in the film thickness direction and increasing the carbon concentration from the glass substrate S side toward the antireflection layer side. It will be possible.
This makes it possible to provide a more suitable mask M that can be used for high-definition FPD manufacturing.

In this embodiment, the same effect as that of the above-described embodiments can be obtained.

Hereinafter, a third embodiment of a mask blank and a mask according to the present invention will be described with reference to the drawings.
FIG. 8 is a cross-sectional view showing a mask blank according to the present embodiment. In the present embodiment, what is different from the above-described first embodiment is a point regarding a stacking order, and other than the above-described first embodiment. Corresponding components will be assigned the same reference numerals and explanations thereof will be omitted.

As shown in FIG. 8, the mask blank MB according to the present embodiment is formed on a transparent substrate (glass substrate) S, an antireflection layer 13 formed on the transparent substrate S, and an antireflection layer 13. The light shielding layer 11B thus formed, the etching rate reducing layer 12 formed on the light shielding layer 11B, and the light shielding layer 11A formed on the etching rate reducing layer 12.
That is, in the mask blank MB according to this embodiment, the light shielding layers 11A and 11B are divided in the thickness direction by the etching rate reducing layer 12.

As described above, in the mask M manufactured from the mask blanks MB according to this embodiment, the recesses X in the light shielding layers 11A and 11B are formed to be large in a state where the desired optical specifications (optical characteristics) are satisfied. Absent.
In addition, the reflectance in the present embodiment can be set to a predetermined value with respect to the light transmitted through the glass substrate S.

In this state, by providing the high oxygen concentration etching rate reducing layer 12 between the light shielding layer 11A and the light shielding layer 11B, a protruding shape in the direction SS near the interface between the antireflection layer 13 and the light shielding layer 11A is formed. It becomes possible to suppress. As a result, excessive etching of the light shielding layers 11A and 11B can be suppressed. Therefore, the deterioration of the pattern shape can be prevented.

In this embodiment, the same effect as that of the above-described embodiments can be obtained.

Hereinafter, a fourth embodiment of a mask blank and a mask according to the present invention will be described with reference to the drawings.
FIG. 9 is a cross-sectional view showing a mask blank according to the present embodiment. In the present embodiment, what is different from the above-described second embodiment is the point regarding the stacking order, and other than the above-described second embodiment. Corresponding components will be assigned the same reference numerals and explanations thereof will be omitted.

As shown in FIG. 9, the mask blank MB according to this embodiment has a transparent substrate (glass substrate) S, an antireflection layer 13 formed on the transparent substrate S, and an antireflection layer 13 on the antireflection layer 13. The formed light-shielding layer 11C, the etching rate reduction layer 12B formed on the light-shielding layer 11C, the light-shielding layer 11B formed on the etching rate reduction layer 12B, and the etching formed on the light-shielding layer 11B. It is composed of a rate reducing layer 12A and a light shielding layer 11A formed on the etching rate reducing layer 12A.
That is, in the mask blank MB according to the present embodiment, the light shielding layers 11A, 11B and 11C are divided into three in the thickness direction by the etching rate reducing layers 12A and 12B.

As described above, in the mask M manufactured from the mask blanks MB according to the present embodiment, the recesses X in the light shielding layers 11A to 11C are formed to be large in a state where the desired optical specifications (optical characteristics) are satisfied. Absent.
In addition, the reflectance in the present embodiment can be set to a predetermined value with respect to the light transmitted through the glass substrate S.

In this embodiment, the same effect as that of the above-described embodiments can be obtained.

Hereinafter, a fifth embodiment of a mask blank and a mask according to the present invention will be described with reference to the drawings.
FIG. 10 is a cross-sectional view showing a mask blank in this embodiment. In this embodiment, what is different from the above-described second embodiment is the number of layers of the antireflection layer, and the other above-described second embodiment. The same reference numerals are given to the configurations corresponding to those of the first embodiment, and the description thereof will be omitted.

As shown in FIG. 10, the mask blank MB according to this embodiment is formed on a transparent substrate (glass substrate) S, an antireflection layer 13B formed on the transparent substrate S, and an antireflection layer 13B. Light shielding layer 11B, etching rate reducing layer 12 formed on light shielding layer 11B, light shielding layer 11A formed on etching rate reducing layer 12, and antireflection formed on light shielding layer 11A And a layer 13A.
That is, in the mask blank MB according to the present embodiment, the antireflection layers 13A and 13B are formed on both surfaces, and the light shielding layers 11A and 11B between them are divided in the thickness direction by the etching rate reduction layer 12.

The antireflection layer 13 contains Cr (chromium) similarly to the light shielding layers 11A and 11B in the thickness direction. Further, the antireflection layer 13 is a chromium oxide film containing O (oxygen). Further, the antireflection layer 13 can contain C (carbon) and/or N (nitrogen). The film thickness of the antireflection layer 13 is set by the exposure wavelength (wavelength region is 365 to 436 nm) when used as a mask in the exposure step, and the required optical density, reflectance, etc. defined by the exposure wavelength.

The antireflection layer 13B has the same layer structure as the antireflection layer 13A.
Further, as the antireflection layer 13B, the reflectance can be reduced by increasing the difference between the refractive index of the antireflection layer 13B and the refractive index of the light shielding layer 11B.
For this reason, it is desirable that the chromium film containing oxygen, nitrogen and carbon used as the antireflection layer 13B has a refractive index of 2.5 or less and an extinction coefficient of 1.0 or less at a wavelength of 365 to 436 nm.

Alternatively, the antireflection layer 13B can be set to have a thickness greater than about 25 nm. Further, the thickness of the antireflection layer 13B is preferably 15 to 40 nm.

At the same time, in order to set the reflectance of the antireflection layer 13B to less than about 5%, it is necessary that the oxygen content rate be within a predetermined range. Specifically, the oxygen content is set to be about 30 atm% or higher. Further, the oxygen concentration contained in the chromium film used as the antireflection layer 13B is preferably 50% or more.

The light-shielding layer 11B serving as the low oxygen concentration region and the antireflection layer 13B serving as the high oxygen region are formed so as to form the interface between them.

Here, the reflectance of the mask blank MB of this embodiment varies depending on the thickness of the light shielding layer 11B, as in the first embodiment shown in FIG. Therefore, in order to realize a low reflectance of about 5% or less, it is necessary to set the thickness of the light shielding layer 11B to 20 nm or more. Here, the measurement wavelength of the reflectance from the glass substrate S side is 405 nm as in FIG.

Further, the reflectance of the mask blank MB of this embodiment varies depending on the thickness of the antireflection layer 13B, as in the first embodiment shown in FIG. Therefore, in order to achieve a low reflectance of about 5% or less, it is necessary to define the thickness of the antireflection layer 13B. Similar to the first embodiment shown in FIG. 6, the film thickness of the light shielding layer 11B is 50 nm, and the reflectance measurement wavelength is 405 nm. Therefore, in order to realize a low reflectance of about 5% or less, it is necessary to set the thickness of the antireflection layer 13B to be around 27 nm.

In the mask M manufactured from the mask blanks MB according to the present embodiment, the recesses X in the light shielding layers 11A and 11B are not formed large in a state where the desired optical specifications (optical characteristics) are satisfied.

FIG. 13 is a cross-sectional view showing an example of a mask in which an antireflection layer is provided on both sides and a light shielding layer is formed as one layer.
Here, similarly to the example shown in FIG. 12, let us consider a case where the light shielding layer 11 is formed as a single layer as shown in FIG.

In this case, as shown in FIG. 13, in the one-layer light-shielding layer 11, when wet-etched, the side surface portion of the transmissive region is excessively etched in the depth direction ss, and thus the side surface portion of the light-shielding layer 11 is removed. The recess X is formed and formed. This state is the state in which the pattern shape has deteriorated.

On the other hand, in the mask blanks MB or the mask M of the present embodiment, the etching rate reduction layer 12 has a higher oxygen concentration and carbon concentration and a lower etching rate than the light shielding layers 11A and 11B, that is, antireflection. It is in a state of having substantially the same etching rate as the layers 13A and 13B. As a result, the etching amount of the etching rate reducing layer 12 in the depth direction ss becomes substantially the same as the etching amount of the antireflection layer 13 at the central position in the total thickness of the light shielding layers 11A and 11B.

Further, the light shielding layers 11A and 11B are divided in the thickness direction, and the etching rate reducing layer 12 is provided between the light shielding layers 11A and 11B, so that the light shielding layer 11A is etched in the depth direction ss. The amount can be suppressed.
Similarly, in the vicinity of the interface between the etching rate reduction layer 12 and the light shielding layer 11B, the light shielding layer 11B can suppress the etching amount in the depth direction ss.

At the same time, the light shielding layers 11A and 11B are divided in the thickness direction as compared with the case of the single light shielding layer 11 shown in FIG. 13, and the etching rate reducing layer 12 is provided between the light shielding layers 11A and 11B. By being provided, the size of the light shielding layer 11A and the light shielding layer 11B in the thickness direction is reduced. Thereby, the etching amount in the depth direction ss in the light shielding layer 11A and the light shielding layer 11B can be suppressed respectively.

In particular, the light-shielding layer 11A is set to have a smaller dimension in the thickness direction, is set to have a slightly higher oxygen concentration and carbon concentration than the light-shielding layer 11B, and is set to have a slightly lower etching rate than the light-shielding layer 11B. .. As a result, the amount of etching in the depth direction ss can be suppressed in the light shielding layer 11A, which is exposed to the etching liquid for a longer time than the light shielding layer 11B. That is, the size of the recess X in the depth direction ss of the light shielding layer 11A and the size of the recess X in the depth direction ss of the light shielding layer 11B can be set to substantially the same value. This can reduce the difference in shape between the light-shielding layers 11A and 11B in the thickness direction.

As a result, as shown in FIG. 13, as compared with the case where the light-shielding layers 11A and 11B are continuous with a total film thickness, the influence of the recess X formed in the depth direction ss is reduced, and the light-transmitting region in the transmission region is reduced. The side surface of the pattern can be formed in a shape close to vertical.

The reflectance in this embodiment can be set to a predetermined value for both the light emitted from the antireflection layer 13A side and the light transmitted through the glass substrate S. That is, the double-sided reflectance of the mask M manufactured from the mask blanks MB according to this embodiment can be set to about 5% or less.

In this embodiment, the same effect as that of the above-described embodiments can be obtained.

Hereinafter, a sixth embodiment of a mask blank and a mask according to the present invention will be described with reference to the drawings.
FIG. 11 is a cross-sectional view showing a mask blank in the present embodiment. In the present embodiment, what is different from the fifth embodiment described above is the number of layers of the antireflection layer, and other than the above-described first embodiment. The same reference numerals are given to the configurations corresponding to those of the fifth embodiment, and the description thereof will be omitted.

As shown in FIG. 11, the mask blank MB according to the present embodiment has a transparent substrate (glass substrate) S, an antireflection layer 13B formed on the transparent substrate S, an antireflection layer 13B, and an antireflection layer. On the light shielding layer 11C formed on the layer 13B, the etching rate reduction layer 12B formed on the light shielding layer 11C, the light shielding layer 11B formed on the etching rate reduction layer 12B, and the light shielding layer 11B. And an antireflection layer 13A formed on the light shielding layer 11A. The etching rate reducing layer 12A formed on the light shielding layer 11A, the light shielding layer 11A formed on the etching rate reducing layer 12A, and the antireflection layer 13A formed on the light shielding layer 11A.
That is, in the mask blank MB according to the present embodiment, the antireflection layers 13A and 13B are formed on both surfaces, and the light shielding layers 11A, 11B and 11C between them are formed in the thickness direction 3 by the etching rate reducing layers 12A and 12B. It is divided into two.

Also in the present embodiment, the mask M manufactured from the mask blanks MB does not have large recesses X in the light shielding layers 11A to 11C in a state where the desired optical specifications (optical characteristics) are satisfied.
Further, the double-sided reflectance of the mask M manufactured from the mask blanks MB according to this embodiment can be set to about 5% or less.

In this embodiment, the same effect as that of the above-described embodiments can be obtained.

Examples of the present invention will be described below.

<Experimental example 1>
First, as Experimental Example 1, a mask blank was produced corresponding to the mask shown in FIG. 13, in which antireflection layers were provided on both surfaces and the light shielding layer was not divided into a plurality of layers.

First, an antireflection layer is formed on a glass substrate for forming a mask to reduce the reflectance from the glass back surface. The antireflection layer formed at this time is preferably a film containing chromium, oxygen, nitrogen, carbon and the like. As the antireflection layer, it is possible to form an antireflection layer having a desired reflectance by controlling the composition and film thickness of chromium, oxygen, nitrogen and carbon.

Since the wavelength range of light used in the exposure process of FPD is 365 to 436 nm, it is required to reduce the reflectance at the wavelength of this range. As the antireflection layer, it is possible to reduce the reflectance by increasing the difference between the refractive index of the antireflection layer and the refractive index of the light shielding layer.

Therefore, it is desirable that the chromium index film containing oxygen, nitrogen, and carbon used as the antireflection layer has a refractive index of 2.5 or less at a wavelength of 365 to 436 nm and an extinction coefficient of 1.0 or less. The thickness of the antireflection layer is preferably 15 to 40 nm. The oxygen concentration contained in the chromium film used as the antireflection layer is preferably 50% or more.

After that, a light-blocking layer is formed using a chromenium film containing oxygen, nitrogen, and carbon. At this time, the film thickness of the light shielding layer is preferably 100 nm or more in order to increase the optical density.
After that, a film similar to the antireflection layer using the chromenium film containing oxygen, nitrogen and carbon described above is formed on the light shielding layer.
At this time, the OD value was set to about 5.

A mask is formed using the mask blanks thus formed.

<Experimental example 2>
Next, as Experimental Example 2, as shown in FIG. 10, a mask blank in which an antireflection layer was provided on both surfaces and the light shielding layer was divided into two layers was manufactured.
In this way, a mask is formed by using the mask blanks in which the light-shielding layer is formed into three layers and one region (etching rate reducing layer) having a high oxygen concentration and a high carbon concentration is formed.

<Experimental example 3>
Further, as Experimental Example 3, as shown in FIG. 11, a mask blank in which an antireflection layer was provided on both surfaces and the light shielding layer was divided into three layers was manufactured.
In this way, a mask is formed by using the mask blanks in which the light-shielding layer is made into five layers and two regions (etching rate reducing layer) having a high oxygen concentration and a high carbon concentration are formed.

Regarding the above Experimental Examples 1 to 3, the OD value and the reflectance of the mask blanks were measured. The results are shown in Table 1.

In the table, the film surface reflectance shows the measurement result of the reflectance on the antireflection layer 13A side laminated on the uppermost position, and the glass surface reflectance shows the measurement result of the reflectance when passing through the glass substrate S.
From these results, it can be seen that the masks of Experimental Examples 1 to 3 can satisfy the desired characteristics in reflectance and optical density.

Cross-sections of the masks were photographed for the above Experimental Examples 1 to 3. The results are shown in FIGS. 14 to 16 are all SEM images.

In the mask of Experimental Example 1, the cross-sectional shape of the mask is such that the light-shielding layer portion is largely etched, as shown in FIG.
This occurs because the etching rate during wet etching differs greatly between the antireflection layer and the light shielding layer.

In the mask of Experimental Example 2, as shown in FIG. 15, it is possible to improve the cross-sectional shape of the mask by forming one layer of a region having a high oxygen concentration and a high carbon concentration (etching rate reducing layer) in the light shielding layer. Recognize.
This is because it is possible to reduce the etching rate of this region (etching rate reduction layer) by increasing the oxygen concentration and the carbon concentration, and suppress the excessive etching of the central portion of the film thickness, which has been a problem in the past. This is because you can

In the mask of Experimental Example 3, as shown in FIG. 16, the cross-sectional shape of the mask can be further improved by forming two regions having a high oxygen concentration and a high carbon concentration (etching rate reducing layer) in the light shielding layer. I understand.
This is because it is possible to reduce the etching rate of this region (etching rate reduction layer) by increasing the oxygen concentration and the carbon concentration, and the excessive etching of the central portion of the film thickness, which has been a problem in the past, is further improved. This is because it can be suppressed.

Moreover, composition analysis was performed about these Experimental Examples 1-3. The results are shown in FIGS.
Here, composition analysis was performed using Auger electron spectroscopy. 17 to 19, the vertical axis represents the concentration (atm %) of each composition, and the horizontal axis represents the sputtering time, which means the distance (depth) from the surface. 17 to 19, the left side shows the surface side where sputtering is started, and the right side shows the glass substrate side.

In the mask blank of Experimental Example 1, as shown in FIG. 17, an antireflection layer having a high oxygen concentration is formed on the surface side in the thickness direction, and a light shielding layer having a high Cr concentration is formed at a central position in the thickness direction. It can be seen that the antireflection layer having a high oxygen concentration is formed on the right side in the thickness direction.

In the mask blank of Experimental Example 2, as shown in FIG. 18, an antireflection layer having a high oxygen concentration is formed on the surface side in the thickness direction, and a light shielding layer having a high Cr concentration is formed at a central position in the thickness direction, It can be seen that the antireflection layer having a high oxygen concentration is formed on the right side in the thickness direction.
In addition, in the mask blank of Experimental Example 2, as shown in FIG. 18, a region having a high oxygen concentration and a high carbon concentration (etching rate reducing layer) is formed in the central portion of the film thickness, and the light shielding layer is divided into three layers. You can confirm that you did.
Further, in the mask blank of Experimental Example 2, as shown in FIG. 18, in the light-shielding layer, the oxygen concentration and the carbon concentration were gradually increased from the glass substrate side to the surface side with the etching rate reduction layer interposed therebetween. It can be seen that they are formed so as to increase.

In the mask blank of Experimental Example 3, as shown in FIG. 19, the antireflection layer having a high oxygen concentration is formed on the surface side in the thickness direction, and the light shielding layer having a high Cr concentration is formed at the center position in the thickness direction. It can be seen that the antireflection layer having a high oxygen concentration is formed on the right side in the thickness direction.
In addition, in the mask blank of Experimental Example 3, as shown in FIG. 19, regions having a high oxygen concentration and a high carbon concentration (etching rate reducing layer) are formed in the second layer and the fourth layer, and the light shielding layer is composed of 5 layers. It can be confirmed that it is divided into layers.
Further, in the mask blank of Experimental Example 3, as shown in FIG. 19, in the light-shielding layer, the oxygen concentration and the carbon concentration were gradually increased from the glass substrate side to the surface side with the etching rate reduction layer interposed therebetween. It can be seen that they are formed so as to increase.

From these results, it was found that the problem of deterioration of the pattern shape can be solved by forming a region having a high oxygen concentration (etching rate reducing layer) in the light shielding layer.

In the present invention, as shown in FIGS. 16 and 19, the structure in which the light-shielding layer is divided into five layers is illustrated, but the number of divisions of the light-shielding layer is preferably 7 or less. Here, it is possible to form three etching rate reducing layers, but it is more preferable that the number of divisions of the light shielding layer is 5 or less, that is, two etching rate reducing layers are formed. This is because if the number of divisions is too large with respect to the film thickness of the light shielding layer required from the optical path length, it becomes difficult to form each layer satisfactorily.

Examples of applications of the present invention include mask blanks and masks for high-definition flat panel displays.

M: Mask (photomask)
MB... Mask blanks 11A, 11B, 11C... Shading layers 11Aa, 11Ba... Shading patterns 12, 12A, 12B... Etching rate reducing layers 13, 13A, 13B... Antireflection layer S... Glass substrate (transparent substrate)
X... recess

Claims (11)

A transparent substrate,
A light-shielding layer formed on the transparent substrate and containing chromium as a main component;
An antireflection layer formed in contact with the light shielding layer and containing chromium as a main component;
Have
The mask blanks, wherein the light-shielding layer has an etching rate reduction layer having an etching rate lower than that of the light-shielding layer, at a position not in contact with the antireflection layer in the thickness direction. The mask blanks according to claim 1, wherein the etching rate reducing layer is provided in one or more layers in the thickness direction of the light shielding layer. The mask blanks according to claim 2, wherein the etching rate reducing layer is provided at a central portion in the thickness direction of the light shielding layer. The mask blanks according to claim 1, wherein the etching rate reducing layer has a higher oxygen concentration than the light shielding layer. The mask blanks according to claim 4, wherein the etching rate reducing layer has a carbon concentration higher than that of the light shielding layer. The oxygen concentration of the light-shielding layer is set to be higher than that of the etching rate reducing layer in contact with the transparent substrate side in the film thickness direction, and further higher than the oxygen concentration of the light-shielding layer located on the transparent substrate side. The mask blank according to claim 4 or 5, characterized in that: The carbon concentration of the light shielding layer is set to be higher than that of the etching rate reducing layer in contact with the transparent substrate side in the film thickness direction, and further compared to the carbon concentration of the light shielding layer located on the transparent substrate side. The mask blanks according to claim 6, wherein The wavelength λ of the exposure light is used in the range of 365 nm to 436 nm,
The mask blank according to any one of claims 1 to 7, wherein the OD value is set to be higher than 5 and the reflectance is set to be lower than 5%. 9. The light shielding layer in contact with the antireflection layer, wherein the film thickness up to the etching rate reducing layer is set to λ*20/405 or more with respect to the wavelength λ. Mask blanks. The film thickness of the antireflection layer is set to λ*25/405 to λ*30/405 or λ*95/405 to λ*100/405 with respect to the wavelength λ. The mask blank according to claim 8. A mask manufactured using the mask blank according to any one of claims 1 to 10.