JP2018106147A - Mask blank substrate for display device production, mask blank and mask, and production method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a substrate for a mask blank and a substrate for a mask blank for manufacturing a display device having a high manufacturing yield when manufacturing the mask blank. SOLUTION: A first main surface on which a thin film to be a transfer pattern is formed, a second main surface provided so as to face the first main surface, a first main surface and a second main surface. A translucent substrate having an end face perpendicular to the surface is provided. The translucent substrate has a mark that identifies the first main surface. The mark is provided on at least one of the first main surface, the second main surface and the end face. The mark can be removed by at least one treatment of mirror polishing of the first main surface and the second main surface, roughening and mirror polishing of the end face, and cleaning of the translucent substrate. [Selection diagram] Fig. 1

Description

  The present invention relates to a mask blank substrate for manufacturing a display device, a mask blank and a mask using the mask blank substrate, and a manufacturing method thereof.

The size of the glass substrate of the mask for manufacturing display devices (smartphones, tablets, televisions, etc.) ranges from G1-G2 size with a short side of 330 mm to G10 size with a short side of over 1600 mm. Larger than a certain 6 inch × 6 inch (6025).
The display device manufacturing mask is used for a longer period of time than the semiconductor manufacturing mask due to the influence of the price reduction of the display device. If used repeatedly, it may become dirty or scratched, making it unusable. The glass substrate of the used mask is recycled from the viewpoint of effectively utilizing resources and the viewpoint of reducing the manufacturing cost because a large size glass substrate is expensive.
In recent years, with the demand for higher definition of display devices, the flatness and parallelism of both main surfaces required for glass substrates of masks for manufacturing display devices have become strict. The defect quality required on the surface is becoming stricter. For example, as a high-precision glass substrate for a high-definition panel, the flatness of the main surface on the side where the thin film is formed is 10 μm or less and the parallelism is 15 μm or less, and the flatness of the main surface is 7 μm or less and the parallelism is 10 μm. The following are required. Further, the defect quality of the main surface on the side where the thin film is formed is required to be free of defects of 2 μm or more, and further to be free of defects of 1.5 μm or more.
In order to specify the main surface on the side where the thin film to be a transfer pattern is formed, the glass substrate of the mask for manufacturing a display device and the mask for manufacturing a semiconductor usually has four corners (that is, corners) on one side of the glass substrate. Any one or more of (section) is provided with a notch mark formed by cutting into an oblique cross section. The notch mark has a cut-off portion having a size of 1.0 to 2.0 mm. In addition, a glass substrate in which notch marks are formed at the corners on the front and back surfaces has been proposed (Patent Document 1).

Korean Published Patent No. 2012-0056905

A glass substrate of a conventional mask is provided with notch marks formed by cutting corner portions on one main surface or both main surfaces. Since the notch mark has a cut-off portion having a size of 1.0 to 2.0 mm, it is difficult to remove the notch mark when recycling the glass substrate of the used mask with the same size.
The glass substrate of the mask needs to satisfy strict requirements for the flatness of the main surface on which the thin film to be the transfer pattern is formed and strict requirements on the defect quality of the main surface on which the thin film to be the transfer pattern is formed. Because of this requirement, when recycling the glass substrate, the same glass surface as the original cannot be used as the film-forming surface, and the opposite glass surface (generally a notch mark is formed). In some cases, the glass surface on the side to be formed is desirable as the film formation surface.
However, depending on the transfer pattern formed on the mask, the transfer pattern may not be formed on the main surface on which the notch mark is formed. For this reason, a mask having a predetermined transfer pattern may not be formed using the recycled glass substrate. As a result, there has been a problem that the manufacturing yield may be reduced when the glass substrate is recycled from the used mask to manufacture the mask blank substrate.

  In addition, when using a mask blank substrate manufactured by recycling a glass substrate from a used mask, the mask must be formed on the main surface on the opposite side of the original, although a thin film to be a transfer pattern must be formed. In the blank manufacturing process, a thin film serving as a transfer pattern is formed on the main surface on the same side as the initial stage, and the film forming process may be wasted. As a result, there is a problem that the manufacturing yield when manufacturing the mask blank may be lowered.

Further, when the above notch mark is formed on the glass substrate, edge sagging occurs in the main surface near the corner where the notch mark is formed, and on the opposite main surface corresponding to the vicinity of the corner, It has been reported that bumps occur (International Publication No. 2012/157629).
For this reason, the glass substrate on which the above-mentioned notch mark is formed may not satisfy the flatness required for the main surface on which the thin film to be the transfer pattern is formed. As a result, there has been a problem that the manufacturing yield may be lowered when manufacturing a mask blank substrate suitable for manufacturing a mask for forming a high-definition pattern.

  For this reason, the present invention has been made in view of the above-mentioned problems, and a mask blank substrate for manufacturing a display device having a high manufacturing yield when manufacturing a mask blank substrate or a mask blank, and for this mask blank. It aims at obtaining the mask blank and mask which used the board | substrate, and those manufacturing methods.

  The inventor has intensively studied to achieve the above-described object, and the mark for specifying the first main surface on which the thin film to be the transfer pattern of the translucent substrate is formed is the manufacturing process of the mask blank substrate. If it can be removed during the manufacturing process of the mask blank, it has been found that it is effective for solving the above-mentioned problems.

  This invention is made | formed based on this knowledge, and has the following structures.

(Configuration 1)
In a mask blank substrate for manufacturing a display device,
A first main surface on which a thin film to be a transfer pattern is formed; a second main surface provided opposite to the first main surface; the first main surface and the second main surface; A translucent substrate having an end surface perpendicular to the
The translucent substrate has a mark that identifies the first main surface;
The mark is provided on at least one of the first main surface, the second main surface, and the end surface,
The mark can be removed by at least one of mirror polishing of the first main surface and the second main surface, surface roughening and mirror polishing of the end surface, and cleaning of the translucent substrate. A mask blank substrate characterized by the above.

(Configuration 2)
The mark includes a rough surface portion provided in an outer peripheral region of the first main surface or the second main surface,
The rough surface portion has a roughness that can be discerned visually or by a difference in optical characteristics between the mark and other regions, and the first main surface or the second surface on which the mark is formed. 2. The mask blank substrate according to Configuration 1, which has a roughness that can be removed by mirror polishing of the main surface.

(Configuration 3)
3. The mask blank substrate according to Configuration 2, wherein the mark is provided at a corner of the first main surface or the second main surface.

(Configuration 4)
The mark includes a mirror surface portion provided on the end surface;
The mirror surface portion has a roughness that can be identified by visual observation or a difference in optical characteristics between the mark and the other region, and can be removed by a roughening treatment of the end surface. 4. The mask blank substrate according to any one of configurations 1 to 3.

(Configuration 5)
The mark includes a rough surface portion provided on the end surface,
The rough surface portion has a roughness that can be discerned visually or by a difference in optical characteristics between the mark and other regions, and has a roughness that can be removed by mirror polishing of the end surface. The mask blank substrate according to any one of configurations 1 to 3.

(Configuration 6)
The mark includes a marker portion containing a water-based dye or a water-based pigment provided on an outer peripheral region or the end surface of the second main surface,
6. The mask blank substrate according to any one of configurations 1 to 5, wherein the marker portion can be removed by cleaning the translucent substrate.

(Configuration 7)
7. The mask blank substrate according to any one of configurations 1 to 6, wherein the translucent substrate is a recycled product obtained by removing a thin film on which a transfer pattern is formed from a used mask.

(Configuration 8)
In a method for manufacturing a mask blank substrate for manufacturing a display device,
A first main surface on which a thin film to be a transfer pattern is formed; a second main surface provided opposite to the first main surface; the first main surface and the second main surface; Providing a translucent substrate having an end face perpendicular to the surface;
Mirror polishing the first main surface and the second main surface of the translucent substrate;
Forming a mark that identifies the first main surface on at least one of the first main surface, the second main surface, and the end surface after the mirror polishing, and
The mark can be removed by at least one of mirror polishing of the first main surface and the second main surface, surface roughening and mirror polishing of the end surface, and cleaning of the translucent substrate. A method for manufacturing a mask blank substrate.

(Configuration 9)
9. The method for manufacturing a mask blank substrate according to Configuration 8, comprising a step of roughening the end face before forming the mark.

(Configuration 10)
9. The method of manufacturing a mask blank substrate according to Configuration 8, comprising a step of mirror polishing the end face before forming the mark.

(Configuration 11)
Obtaining at least one surface information of flatness, surface roughness, and defect information of the first main surface and the second main surface after the mirror polishing,
11. The method for manufacturing a mask blank substrate according to any one of Structures 8 to 10, wherein the mark is formed according to the surface information.

(Configuration 12)
12. The mask blank substrate according to any one of Structures 8 to 11, wherein the translucent substrate is a recycled product obtained by removing a thin film on which a transfer pattern is formed from a used mask. Production method.

(Configuration 13)
In mask blanks for manufacturing display devices,
A first main surface on which a thin film to be a transfer pattern is formed; a second main surface provided opposite to the first main surface; the first main surface and the second main surface; A mask blank substrate including a translucent substrate having an end surface perpendicular to the substrate;
A thin film serving as a transfer pattern formed on the first main surface of the translucent substrate,
The translucent substrate has a mark that identifies the first main surface;
The mark is provided on at least one of the first main surface, the second main surface, and the end surface,
The mask blank, wherein the mark can be removed by at least one of a mirror polishing of the first main surface and the second main surface, and a roughening process and a mirror polishing of the end face.

(Configuration 14)
In a method for manufacturing a mask blank for manufacturing a display device,
A first main surface on which a thin film to be a transfer pattern is formed; a second main surface provided opposite to the first main surface; the first main surface and the second main surface; Providing a mask blank substrate including a translucent substrate having an end surface perpendicular to the surface;
Cleaning the mask blank substrate;
Forming a thin film to be a transfer pattern on the first main surface of the translucent substrate after cleaning, and
The translucent substrate has a mark that identifies the first main surface;
The mark is provided on at least one of the first main surface, the second main surface, and the end surface,
The mark can be removed by at least one of mirror polishing of the first main surface and the second main surface, surface roughening and mirror polishing of the end surface, and cleaning of the translucent substrate. A method of manufacturing a mask blank characterized by the above.

(Configuration 15)
In a mask for manufacturing a display device,
A first main surface on which a thin film to be a transfer pattern is formed; a second main surface provided opposite to the first main surface; the first main surface and the second main surface; A mask blank substrate including a translucent substrate having an end surface perpendicular to the substrate;
A thin film having a transfer pattern formed on the first main surface of the translucent substrate,
The translucent substrate has a mark that identifies the first main surface;
The mark is provided on at least one of the first main surface, the second main surface, and the end surface,
The mark can be removed by at least one of a mirror polishing of the first main surface and the second main surface, and a roughening process and a mirror polishing of the end face.

(Configuration 16)
In a manufacturing method of a mask for manufacturing a display device,
A first main surface on which a thin film to be a transfer pattern is formed; a second main surface provided opposite to the first main surface; the first main surface and the second main surface; A mask blank including a light-transmitting substrate having an end surface perpendicular to the light-transmitting substrate and a thin film serving as a transfer pattern formed on the first main surface of the light-transmitting substrate is prepared. Process,
Forming a transfer pattern on the thin film,
The translucent substrate has a mark that identifies the first main surface;
The mark is provided on at least one of the first main surface, the second main surface, and the end surface,
The mark can be removed by at least one of mirror polishing of the first main surface and the second main surface, and roughening processing of the end surface and mirror polishing. .

  As described above, the mask blank substrate for manufacturing a display device according to the present invention includes a translucent substrate, and the translucent substrate has a mark that identifies the first main surface, The mark is provided on at least one of the first main surface, the second main surface, and the end surface, and the marks are mirror-polished on the first main surface and the second main surface, roughened and mirror-polished on the end surface, and transparent. It can be removed by at least one process of cleaning the optical substrate. For this reason, when manufacturing a mask blank using this mask blank substrate, or when manufacturing a mask blank substrate by recycling a translucent substrate from a mask manufactured using this mask blank substrate. The above-mentioned marks are removed by at least one of mirror polishing of the first main surface and the second main surface, roughening and mirror polishing of the end surface of the translucent substrate, and cleaning of the translucent substrate. can do. As a result, the mask blank substrate and the mask blank are not produced due to the notch mark formed by cutting the corner portion of the main surface of the translucent substrate, and the manufacturing yield of the mask blank and the mask blank are manufactured. A mask blank substrate for manufacturing a display device with a high manufacturing yield can be obtained. When such a mask blank substrate is used, the manufacturing yield of the mask blank and the mask is also increased.

It is a figure which shows the 1st example of the mark provided in the board | substrate for mask blanks. It is a figure which shows the 2nd example of the mark provided in the board | substrate for mask blanks. It is a figure which shows the 3rd example of the mark provided in the board | substrate for mask blanks. It is a figure which shows the 4th example of the mark provided in the board | substrate for mask blanks. It is a figure which shows the 5th example of the mark provided in the board | substrate for mask blanks. It is a figure which shows the 6th example of the mark provided in the board | substrate for mask blanks. It is a figure which shows the 7th example of the mark provided in the board | substrate for mask blanks.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In addition, the following embodiment is one form at the time of actualizing this invention, Comprising: This invention is not limited within the range. In the drawings, the same or equivalent parts may be denoted by the same reference numerals, and the description thereof may be simplified or omitted.

Embodiment 1 FIG.
In Embodiment 1, a mask blank substrate for manufacturing a display device and a manufacturing method thereof will be described.

<Mask blank substrate>
The mask blank substrate according to the first embodiment includes a first main surface on which a thin film to be a transfer pattern is formed, a second main surface provided to face the first main surface, and a first main surface. A translucent substrate having a surface and an end surface perpendicular to the second major surface. The translucent substrate has a mark that identifies the first main surface. The mark is provided on at least one of the first main surface, the second main surface, and the end surface. The mark can be removed by at least one of mirror polishing of the first main surface and the second main surface, roughening and mirror polishing of the end surfaces, and cleaning of the translucent substrate.

The light-transmitting substrate may be formed by subjecting a substrate cut from an ingot or the like to processing such as polishing, or a thin film on which a transfer pattern is formed from a used mask. It may be a recycled product formed by subjecting to a processing such as polishing.
The first main surface and the second main surface of the translucent substrate have a rectangular shape with a side length of 330 mm or more. For example, the length × width is preferably 330 mm × 450 mm to 1220 mm × 1400 mm.
The light-transmitting substrate is made of a material containing silicon and oxygen, and is formed of a glass material such as synthetic quartz glass, quartz glass, aluminosilicate glass, soda lime glass, low thermal expansion glass (SiO ₂ —TiO ₂ glass or the like). be able to.
The first main surface and the second main surface of the translucent substrate are mirror-polished. The flatness of the first main surface is preferably 10 μm or less, more preferably 7 μm or less, and even more preferably 5 μm or less. The flatness of the second main surface is preferably 20 μm or less, more preferably 15 μm or less, and further preferably 10 μm or less. The parallelism of the translucent substrate is preferably 20 μm or less, more preferably 15 μm or less, and further preferably 10 μm or less. Further, the first main surface preferably has no defects of 5 μm or more, and more preferably has no defects of 2 μm or more. The second main surface preferably has no defects of 20 μm or more, and more preferably has no defects of 10 μm or more.
The end face of the translucent substrate may be roughened or mirror-polished. When the end surface of the light-transmitting substrate is roughened, the possibility of sliding the light-transmitting substrate when the light-transmitting substrate is gripped and transported can be reduced. In this case, the end face of the translucent substrate is preferably 0.05 μm or more, and more preferably 0.1 μm or more in terms of arithmetic average roughness (hereinafter, the arithmetic average roughness is referred to as Ra). When the end surface of the translucent substrate is mirror-polished, it is possible to suppress generation of particles or the like from the end surface that cause defects on the first main surface and the second main surface. In this case, the end surface of the translucent substrate is preferably 0.03 μm or less in Ra, and more preferably 0.02 μm or less.

  The mark for specifying the first main surface is provided on at least one of the first main surface, the second main surface, and the end surface, and the first main surface and the second main surface are mirror-polished and the end surface is rough. It can be removed by at least one of surface treatment, mirror polishing, and cleaning of the translucent substrate.

Hereinafter, examples of marks will be described.
1. As an example of the rough surface portion mark formed in the outer peripheral region of the main surface, a mark composed of a rough surface portion provided in the outer peripheral region of the first main surface that has been mirror-polished or the second main surface that has been mirror-polished. Can be mentioned. In the case of this mark, in the configuration in which the mark is provided on the first main surface, the side on which the rough surface portion is provided can be specified as the first main surface, and in the configuration in which the mark is provided on the second main surface, The side opposite to the side where the rough surface portion is provided can be specified as the first main surface. In the configuration in which the mark is provided on the first main surface, the rough surface portion can be used as a reference position for the defect map and the optical property data map of the first main surface of the translucent substrate. The rough surface portion has a roughness that can be discerned visually or by a difference in optical characteristics between the mark and the other region, and the first main surface or the second main surface on which the mark is formed is mirror-polished. It has a removable roughness. As an optical characteristic for identifying the mark and the other area, reflectance and transmittance can be cited.
The outer peripheral region where the rough surface portion is provided is preferably a region within 10 mm from the outer peripheral edge of the first main surface or the second main surface of the translucent substrate, and more preferably within a region within 2 mm. preferable. If a rough surface portion is provided in a region exceeding 10 mm, there is a possibility of overlapping with the film formation region on the first main surface of the translucent substrate.
The position of the rough surface portion is not particularly limited as long as it is an outer peripheral region, but a corner portion (that is, a corner portion) is preferable because it is the same position as a conventional notch mark.
The first main surface and the second main surface are mirror-polished with a slurry containing abrasive grains such as cerium oxide and colloidal silica so that the surface roughness Ra is 0.5 nm or less. . The surface roughness of the mirror-polished first main surface and second main surface is preferably 0.3 nm or less, and more preferably 0.2 nm or less, in terms of Ra.
On the other hand, the roughness of the rough surface part is preferably 0.05 μm or more in Ra. When the Ra is 0.05 μm or more, the rough surface portion can be identified by visual observation or by a difference in optical characteristics between the mark and the other region. The roughness of the rough surface portion is preferably 0.2 μm or less in terms of Ra. When the Ra is 0.2 μm or less, the rough surface portion can be removed by mirror polishing of the first main surface or the second main surface on which the mark is formed. The roughness of the rough surface portion is preferably 0.05 μm or more and 0.2 μm or less in Ra, and more preferably 0.05 μm or more and 0.15 μm or less in Ra.
The shape and size of the rough surface portion are not particularly limited as long as the shape and size can be identified visually or by the difference in optical characteristics between the mark and other regions.
The rough surface portion can be formed by etching or sand blasting using a roughening agent. Examples of the roughening agent include a fluorine-based etching solution such as a hydrofluoric acid aqueous solution.
In the case of forming a rough surface portion by etching using a roughening agent, for example, the roughening agent is applied to the outer peripheral region of the first main surface or the second main surface and left for a predetermined time. At the stage where the surface to which the surface roughening agent is applied has become a predetermined roughness, the translucent substrate is washed to remove the surface roughening agent. When the rough surface portion is formed by sandblasting, for example, abrasive grains # 600 to # 3000 are blown with air.
The rough surface portion provided in the outer peripheral region of the first main surface or the second main surface is a process of manufacturing a mask blank substrate from a used mask described later (that is, a mask blank substrate is used from a used mask). In the recycling process), the first main surface and the second main surface can be removed when mirror polishing.

2. As another example of the mirror surface mark formed on the end surface, a mark composed of a mirror surface portion provided on the end surface may be mentioned. This mark can be applied to a roughened end face. In the case of this mark, by making the mirror surface part into a predetermined shape (for example, an untargeted shape in the thickness direction), or by providing the mirror surface part at a position shifted from the center position in the thickness direction of the translucent substrate. The first main surface can be specified. The mirror surface portion has a roughness that can be discerned by visual observation or by a difference in optical characteristics between the mark and the other region, and can be removed by roughening the end surface. As an optical characteristic for identifying the mark and the other area, reflectance and transmittance can be cited.
As described above, the surface roughness of the end face subjected to the roughening treatment is preferably 0.05 μm or more in terms of Ra.
On the other hand, the roughness of the mirror surface portion is preferably 0.03 μm or less in terms of Ra. When the Ra is 0.03 μm or less, the mirror surface portion can be identified by visual observation or by the difference in optical characteristics between the mark and the other region.
The magnitude | size of a mirror surface part will not be restrict | limited especially if it is a magnitude | size discriminable by visual observation or the difference of the optical characteristic of a mark and an area | region other than that.
The mirror surface portion can be formed by partial mirror polishing using a rotary processing tool with a polishing pad attached thereto.
When forming the mirror surface portion, for example, a polishing pad is attached to a cylindrical rotary processing tool having a diameter smaller than the thickness of the mask blank substrate, and a slurry containing abrasive grains such as cerium oxide or colloidal silica is added. While being supplied between the polishing pad and the translucent substrate, the polishing pad and the translucent substrate are brought into contact with each other while relatively moving.
The mirror surface portion provided on the end face is used for the end face of the translucent substrate in the process of manufacturing a mask blank substrate from a used mask described later (that is, the process of recycling the mask blank substrate from the used mask). It can be removed during the roughening treatment.

3. As another example of the rough surface mark formed on the end face, a mark composed of a rough face provided on the end face can be mentioned. This mark can be applied to the end surface which is mirror-finished. In the case of this mark, by making the rough surface portion into a predetermined shape (for example, an untargeted shape in the thickness direction), or by providing the rough surface portion at a position shifted from the center position in the thickness direction of the translucent substrate. The first main surface can be specified. The rough surface portion has a roughness that can be discerned by visual observation or a difference in optical characteristics between the mark and the other region, and has a roughness that can be removed by mirror polishing of the end surface. As an optical characteristic for identifying the mark and the other area, reflectance and transmittance can be cited.
As described above, the surface roughness of the mirror-polished end face is preferably 0.03 μm or less in terms of Ra.
The roughness of the rough surface portion is preferably 0.05 μm or more in Ra. When the Ra is 0.05 μm or more, the mirror surface portion can be identified by visual observation or by the difference in optical characteristics between the mark and the other region. The roughness of the rough surface portion is preferably 0.2 μm or less in terms of Ra. When the surface roughness Ra is 0.2 μm or less, the rough surface portion can be removed by mirror polishing of the end surface. The roughness of the rough surface portion is preferably 0.05 μm or more and 0.2 μm or less in Ra, and more preferably 0.05 μm or more and 0.15 μm or less in Ra.
The size of the rough surface portion is not particularly limited as long as it is a size that can be identified visually or by a difference in optical characteristics between the mark and other regions.
The rough surface portion can be formed by etching or sand blasting using a roughening agent. As the roughening agent, as described above, a fluorine-based etching solution such as a hydrofluoric acid aqueous solution may be used.
In the case of forming a rough surface portion by etching using a roughening agent, for example, a roughening agent is applied to the end face and left for a predetermined time. At the stage where the surface to which the surface roughening agent is applied has become a predetermined roughness, the translucent substrate is washed to remove the surface roughening agent. When the rough surface portion is formed by sandblasting, for example, abrasive grains # 600 to # 3000 are blown with air.
The rough surface portion provided on the end face is used to form the end face of the translucent substrate in the process of manufacturing a mask blank substrate from a used mask, which will be described later (that is, the process of recycling the mask blank substrate from the used mask). It can be removed when mirror polishing.

4). The marker part formed in the outer peripheral area or end face of the second main surface As another example of the mark, the mark part is formed on the outer peripheral area or end face of the second main surface and includes a marker part containing an aqueous dye or an aqueous pigment. What is done. In the case of this mark, in the configuration in which the mark is provided on the second main surface, the side opposite to the side on which the marker portion is attached can be specified as the first main surface. Moreover, in the structure which puts a mark on an end surface, the mark part is shifted from the center position in the thickness direction of the translucent substrate by making the mark part into a predetermined shape (for example, an untargeted shape in the thickness direction) By attaching to the position, the first main surface can be specified. The marker part can be removed by cleaning the translucent substrate.
In the configuration in which the mark is applied to the second main surface, the outer peripheral region to which the marker portion is attached and the position of the marker portion are determined from the rough surface portion where the mark is provided on the first main surface or the outer peripheral region of the second main surface. It is the same as the case where it is comprised.
As described above, the second main surface is mirror-polished with a slurry containing abrasive grains such as cerium oxide and colloidal silica so that the surface roughness Ra is 0.5 nm or less. The surface roughness of the mirror-polished second main surface is preferably 0.3 nm or less in terms of Ra, and more preferably 0.2 nm or less. The end face may be either roughened or mirror-polished. As described above, the surface roughness of the end surface subjected to the roughening treatment is preferably 0.05 μm or more as Ra, and the surface roughness of the end surface subjected to mirror polishing is 0.03 μm as Ra as described above. The following is preferable.
The shape and size of the marker portion are not particularly limited as long as the shape and size can be identified visually.
The marker part can be formed by a writing instrument using an aqueous dye or an aqueous pigment as an ink, such as a sign pen or a fluorescent pen.
When forming the marker portion, for example, an arbitrary shape is written on the outer peripheral region or the end surface of the second main surface with a writing tool such as a sign pen.
The marker portion attached to the outer peripheral region or the end surface of the second main surface can be removed when cleaning the translucent substrate in the process of manufacturing a mask blank described later.

5. As another example of the concave mark formed in the outer peripheral region or end surface of the main surface, there is one constituted by a concave portion provided in the outer peripheral region or end surface of the first main surface or the second main surface. In the case of this mark, in the configuration in which the mark is provided on the first main surface, the side on which the concave portion is provided can be specified as the first main surface, and in the configuration in which the mark is provided on the second main surface, the concave portion The side opposite to the side on which is provided can be specified as the first main surface. In the configuration in which the mark is provided on the first main surface, the concave portion can be used as a reference position for a defect map or an optical property data map on the first main surface of the translucent substrate. Further, in the configuration in which the mark is provided on the end face, the plurality of concave portions are formed so as to be recognized as asymmetric shapes, or the single or plural concave portions are displaced from the center position in the thickness direction of the translucent substrate. By forming at the position, the first main surface can be specified. The recess has a depth that can be discerned visually or by a difference in optical characteristics between the mark and the other region, and mirror polishing of the first main surface or the second main surface on which the mark is formed, Alternatively, it has a depth that can be removed by mirror polishing or roughening of the end face. As an optical characteristic for identifying the mark and the other area, reflectance and transmittance can be cited.
In the configuration in which the mark is provided on the first main surface or the second main surface, the mark is provided in the outer peripheral region of the first main surface or the second main surface with respect to the position of the outer peripheral region and the concave portion provided with the concave portion. This is the same as the case of being composed of a rough surface portion.
As described above, the first main surface and the second main surface are mirror-finished so that the surface roughness is 0.5 nm or less by a slurry containing abrasive grains such as cerium oxide and colloidal silica. Polished. The surface roughness of the mirror-polished first main surface and second main surface is preferably 0.3 nm or less, and more preferably 0.2 nm or less, in terms of Ra. In addition, the end face may be either roughened or mirror-polished, but for easy identification by visual observation or by the difference in optical characteristics between the mark and other areas. Further, it is preferable that the surface is mirror-polished. The surface roughness of the end surface subjected to the roughening treatment is preferably 0.05 μm or more in Ra and not more than a surface roughness that can be distinguished from the depth of the recess, and the surface roughness of the end surface that is mirror-polished. As described above, Ra is preferably 0.03 μm or less.
On the other hand, the depth of the recess is preferably 1 μm or more. When it is 1 μm or more, the concave portion can be identified by visual observation or by a difference in optical characteristics between the mark and the other region. The depth of the recess is preferably 5 μm or less. When the thickness is 5 μm or less, the concave portion is removed by mirror polishing of the first main surface or the second main surface where the concave portion is formed, or by mirror polishing or roughening treatment of the end surface where the concave portion is formed. Can do.
The shape and size of the recess are not particularly limited as long as the shape and size can be identified by visual observation or by the difference in optical characteristics between the mark and other regions.
The recess can be formed by a diamond needle or a minute indenter.
When forming the recess, for example, a diamond needle is scanned on the glass substrate to form a processing mark, or a minute indenter is pushed into the glass substrate (indentation).
The concave portion provided in the outer peripheral region of the first main surface or the second main surface is a process of manufacturing a mask blank substrate from a used mask described later (that is, the mask blank substrate is recycled from the used mask). In the process, the first main surface and the second main surface can be removed when mirror polishing. In addition, the concave portion provided on the end surface is an end surface of the translucent substrate in the process of manufacturing a mask blank substrate from a used mask described later (that is, the process of recycling the mask blank substrate from the used mask). Can be removed during mirror polishing or roughening treatment.

6). Other examples of laser marking marks formed on the outer peripheral area or end face of the main surface include those composed of laser marking provided on the outer peripheral area or end face of the first main surface or the second main surface. . In the case of this mark, in the configuration in which the mark is provided on the first main surface, the side on which the laser marking is provided can be specified as the first main surface, and in the configuration in which the mark is provided on the second main surface, The side opposite to the side where the laser marking is provided can be identified as the first main surface. In a configuration in which a mark is provided on the first main surface, this laser marking can be used as a reference position for a defect map or optical property data map on the first main surface of the translucent substrate. Further, in the configuration in which the mark is provided on the end face, a plurality of laser markings are formed so as to be recognized as an asymmetric shape, or one or a plurality of laser markings are formed from the center position in the thickness direction of the translucent substrate. By forming at a shifted position, the first main surface can be specified. Laser marking can be identified by visual observation or by a difference in optical characteristics between the mark and the other area, and mirror polishing of the first main surface or the second main surface on which the mark is formed, or an end surface It is formed in a depth range that can be removed by mirror polishing or roughening treatment. As an optical characteristic for identifying the mark and the other area, reflectance and transmittance can be cited.
In the configuration in which the mark is provided on the first main surface or the second main surface, the outer periphery region where the laser marking is provided and the position of the laser marking are arranged on the outer periphery region of the first main surface or the second main surface. This is the same as the case where the rough surface portion is provided.
As described above, the first main surface and the second main surface are mirror-finished so that the surface roughness is 0.5 nm or less by a slurry containing abrasive grains such as cerium oxide and colloidal silica. Polished. The surface roughness of the mirror-polished first main surface and second main surface is preferably 0.3 nm or less, and more preferably 0.2 nm or less, in terms of Ra. In addition, the end face may be either roughened or mirror-polished, but for easy identification by visual observation or by the difference in optical characteristics between the mark and other areas. Further, it is preferable that the surface is mirror-polished. As described above, the surface roughness of the end surface subjected to the roughening treatment is preferably 0.05 μm or more as Ra, and the surface roughness of the end surface subjected to mirror polishing is 0.03 μm as Ra as described above. The following is preferable.
On the other hand, the depth at which the laser marking is formed is preferably 5 μm or less from the first main surface, the second main surface or the end surface on which the laser marking is formed. When the thickness is 5 μm or less, laser marking is performed by mirror polishing of the first main surface or the second main surface on which laser marking is formed, or by mirror polishing or roughening of the end surface on which laser marking is formed. Can be removed.
The shape and size of the laser marking are not particularly limited as long as the shape and size can be identified visually or by a difference in optical characteristics between the mark and other regions.
The laser marking can be formed by a YAG laser, a carbon dioxide gas laser, or the like.
The laser marking provided in the outer peripheral region of the first main surface or the second main surface is a process of manufacturing a mask blank substrate from a used mask described later (that is, a mask blank substrate is converted from a used mask). In the recycling process), the first main surface and the second main surface can be removed when mirror polishing. In addition, the laser marking provided on the end surface is used for the translucent substrate in the process of manufacturing a mask blank substrate from a used mask described later (that is, the process of recycling the mask blank substrate from the used mask). It can be removed when the end face is mirror-polished or roughened.

  According to the mask blank substrate of the first embodiment, the mark for identifying the first main surface provided on the translucent substrate is mirror-polished on the first main surface and the second main surface, It can be removed by at least one of roughening treatment, mirror polishing, and cleaning of the light-transmitting substrate. For this reason, when manufacturing a mask blank using this mask blank substrate, or when manufacturing a mask blank substrate by recycling a translucent substrate from a mask manufactured using this mask blank substrate. The above-mentioned marks are removed by at least one of mirror polishing of the first main surface and the second main surface, roughening and mirror polishing of the end surface of the translucent substrate, and cleaning of the translucent substrate. can do. As a result, the mask blank substrate and the mask blank are not produced due to the notch mark formed by cutting the corner portion of the main surface of the translucent substrate, and the manufacturing yield of the mask blank and the mask blank are manufactured. A mask blank substrate for manufacturing a display device with a high manufacturing yield can be obtained. When such a mask blank substrate is used, the manufacturing yield of the mask blank and the mask is also increased.

<Manufacturing method of mask blank substrate>
The method for manufacturing a mask blank substrate according to the first embodiment includes a step of preparing a light-transmitting substrate, a step of mirror-polishing the first main surface and the second main surface of the light-transmitting substrate, and after mirror polishing Forming a mark for identifying the first main surface on at least one of the first main surface, the second main surface, and the end face. The mark can be removed by at least one of mirror polishing of the first main surface and the second main surface, roughening and mirror polishing of the end surfaces, and cleaning of the translucent substrate.
When the end face is roughened, the end face is roughened before the mark is formed. When the end face is mirror-polished, the end face is mirror-polished before the mark is formed. Have
Including a step of acquiring at least one surface information of flatness, surface roughness, and defect information of the first main surface and the second main surface after mirror polishing, and a mark is formed according to the surface information It is preferable.
The translucent substrate to be prepared may be a substrate cut out from an ingot or the like, or may be a recycled product obtained by removing a thin film on which a transfer pattern is formed from a used mask.
Details of the translucent substrate and the mark are as described above.
Hereinafter, the manufacturing method of the mask blank substrate of Embodiment 1 will be described in detail.

(Translucent substrate preparation process)
First, a surface obtained by cutting out an ingot or the like into a substrate shape is subjected to surface grinding of one main surface and the other main surface to obtain a light-transmitting substrate.
When the translucent substrate is a recycled product, the translucent substrate is obtained by removing the thin film on which the transfer pattern is formed from the used mask. In order not to damage the light-transmitting substrate, it is desirable to remove this thin film using a wet etching solution that can provide a sufficient etching rate difference with respect to the light-transmitting substrate. Specifically, when a chromium-based material is used as the thin film, it is preferable to use a chromium etching solution containing ceric ammonium nitrate and perchloric acid. When the thin film is made of a MoSi-based material, it is preferable to use an etching solution containing ammonium hydrogen fluoride and hydrogen peroxide.

(Substrate thickness inspection process)
Next, the substrate plate thickness is measured by using a substrate plate thickness measuring machine (for example, a flatness tester (manufactured by Kuroda Seiko Co., Ltd.)) to inspect whether the plate thickness has a sufficient polishing allowance. The standard for the judgment is a plate thickness obtained by adding 100 μm to the specification of the plate thickness lower limit. For example, when the lower limit specification of the thickness of a light-transmitting substrate having a size of 800 mm × 920 mm × 10 mm is 9.8 mm, it is inspected whether there is a thickness of 9.9 mm or more.
If there is a sufficient polishing allowance for the plate thickness, the process proceeds to the inspection of scratches on the surface of the translucent substrate.

(Scratch defect inspection process)
In the scratch defect inspection, the scratch defect of the translucent substrate is inspected by visual inspection or the like. This defect inspection is performed on both main surfaces. When there is no damage (when no scratch is found), the process proceeds to the flatness calculation step.
The scratch defect inspection process may be performed before the substrate plate thickness inspection process or after the flatness calculation process.

(Flatness calculation process)
In the flatness calculating step, first, the shapes of both main surfaces of the translucent substrate are measured by the surface form information measuring device, and then the flatness is calculated based on the measurement data. Here, depending on a measuring device such as a flat tester manufactured by Kuroda Seiko Co., Ltd., the substrate plate thickness and the flatness can be obtained together as the surface morphology information.

(Local wet etching process)
In the local wet etching step, the local etching is performed by bringing the wet etching solution into contact with the region of the main surface of at least one of the main surfaces that is relatively convex at least beyond the allowable value. .
Since local wet etching is chemical etching, damage to the surface of the translucent substrate is small, and as a result, machining allowance can be reduced.
Examples of the chemical solution (wet etching solution) when performing local wet etching include hydrofluoric acid aqueous solution, alkaline aqueous solution such as KOH and NaOH, and phosphoric acid.
After performing the local wet etching process, the process proceeds to a mirror polishing process.

(Mirror polishing process)
In the mirror polishing step, both main surfaces of the translucent substrate are polished to further increase the flatness and parallelism and improve the surface smoothness. Here, in this polishing, for example, both sides are polished one by one using a single-side polishing apparatus. In this polishing, instead of polishing one surface at a time using a single-side polishing apparatus, both surfaces may be simultaneously polished using a double-side polishing apparatus.
The mirror polishing process is selected from one-step polishing to multi-step polishing in accordance with required values of flatness and parallelism. In multi-stage polishing, it is preferable to use final polishing for smoothing the surface of the light-transmitting substrate, and to improve flatness and parallelism in the previous polishing. And in order to improve flatness and parallelism, it is preferable to acquire surface form information in the middle stage and feed back the information to polishing conditions.
When the translucent substrate is a recycled product, a mark composed of a rough surface portion provided in an outer peripheral region of the first main surface or the second main surface, which is given before recycling in a mark forming step described later, Constructed from a recess formed in the outer peripheral region of the first main surface or the second main surface, and a laser marking provided in the outer peripheral region of the first main surface or the second main surface The marks to be removed are removed in this step.

(Surface information acquisition process)
After the mirror polishing, at least one surface information of flatness, surface roughness, and defect information on both the first main surface and the second main surface of the translucent substrate is acquired.
The flatness is calculated and acquired in the same manner as the flatness calculation step described above. The defect information is acquired using a defect inspection apparatus or the like. The surface roughness is obtained using a surface roughness measuring instrument (for example, Mitutoyo SJ-210).

(Mark formation process)
A mark that identifies the first main surface is formed on at least one of the first main surface, the second main surface, and the end surface after mirror polishing. The mark is preferably formed according to the surface information obtained in the surface information acquisition step. For example, when the surface information obtained in the surface information acquisition step is the flatness of both surfaces, a surface satisfying the specifications of the mask blank substrate is set as the first main surface, and a mark for specifying the surface is formed.
When the mark is composed of a rough surface portion provided in the outer peripheral region of the first main surface or the second main surface, the mark is formed by etching using a roughening agent, sandblasting, or the like. .
When the mark is composed of a mirror surface portion provided on the end surface, the mark is formed by partial mirror polishing using a rotary processing tool with a polishing pad attached thereto. In this case, it is preferable that the step of roughening the end face is performed before the surface information acquisition step. The roughening treatment of the end face is performed by etching using a roughening agent, sandblasting treatment, or the like.
When the mark is composed of a rough surface portion provided on the end surface, the mark is formed by etching using a roughening agent, sandblasting, or the like. In this case, it is preferable to perform the step of mirror-polishing the end surface before the surface information acquisition step. Mirror polishing of the end face is performed by supplying a slurry containing abrasive grains such as cerium oxide and colloidal silica between the polishing pad or brush and the light-transmitting substrate, and polishing pad or brush and light-transmitting substrate. Is carried out by bringing them into contact with each other while relatively moving.
When the mark is composed of a marker part containing a water-based dye or a water-based pigment attached to the outer peripheral region or the end face of the second main surface, a water-based dye or water-based material such as a sign pen or a fluorescent pen It is formed by a writing instrument using a pigment as an ink.
In the case where the mark is composed of a concave portion provided in the outer peripheral region or end face of the first main surface or the second main surface, a pressurization mark obtained by scanning a diamond needle, or an indentation by a fine indenter And so on.
When the mark is composed of a laser marking provided on the outer peripheral region or end face of the first main surface or the second main surface, the mark is formed by a YAG laser, a carbon dioxide gas laser, or the like.

  A mask blank substrate is manufactured by performing the process up to the mark forming step.

  If the translucent substrate is a recycled product, it is provided on the end surface, a mark formed from a mirror surface portion provided on the end surface, a mark formed from a rough surface portion provided on the end surface, and provided before recycling. The mark constituted by the concave portion and the mark constituted by the laser marking provided on the end face are removed by performing a roughening process on the end face or a mirror polishing process on the end face before the surface information acquisition process. .

Embodiment 2. FIG.
In Embodiment 2, a mask blank for manufacturing a display device and a manufacturing method thereof will be described.

<Mask blank>
The mask blank according to the second embodiment includes a mask blank substrate including a translucent substrate and a thin film serving as a transfer pattern formed on the first main surface of the mask blank substrate. The translucent substrate has a mark that identifies the first main surface. The mark is provided on at least one of the first main surface, the second main surface, and the end surface. The mark can be removed by mirror polishing of the first main surface and the second main surface, and at least one of roughening processing of the end surface and mirror polishing.
Details of the translucent substrate and the mark are as described above.

<Manufacturing method of mask blank>
The mask blank manufacturing method of the second embodiment includes a step of preparing a mask blank substrate including a light transmitting substrate, a step of cleaning the mask blank substrate, and a first main of the light transmitting substrate after cleaning. Forming a thin film to be a transfer pattern on the surface. The translucent substrate has a mark that identifies the first main surface. The mark is provided on at least one of the first main surface, the second main surface, and the end surface. The mark can be removed by at least one of mirror polishing of the first main surface and the second main surface, roughening and mirror polishing of the end surfaces, and cleaning of the translucent substrate.
Details of the translucent substrate and the mark are as described above.
Hereinafter, the manufacturing method of the mask blank of Embodiment 2 will be described in detail.

(Mask blank substrate preparation process)
First, the mask blank substrate manufactured in the first embodiment is prepared.

(Mask blank substrate cleaning process)
Next, the mask blank substrate manufactured in the first embodiment is cleaned.
In this step, the mark composed of the marker portion is removed.

(Thin film formation process)
Next, a thin film to be a transfer pattern is formed on the mask blank substrate manufactured in the first embodiment.
As this thin film, a mask suitable for each type of mask, that is, a binary mask (a normal photomask having a light-shielding film pattern formed on a mask blank substrate), a halftone phase shift mask, or the like is used. A sputtering method is preferably used as a method for forming the thin film, but is not limited to the sputtering method.
For example, in a mask blank used for a binary mask, as a thin film, a material mainly composed of Cr such as Cr, CrO, CrN, CrC, CrON, CrOC, CrCN, CrCON can be preferably used. The thickness of the thin film is set to a thickness that shields exposure light and has an optical density OD of 2.0 or more, preferably 2.5 or more, and more preferably 3.0 or more.
In the case of a mask blank (phase shift mask blank) used for a halftone phase shift mask, the thin film is a phase shift film for obtaining a predetermined transmittance and phase difference with respect to exposure light. This phase shift film is a film having a function of causing a phase difference of approximately 180 ° (for example, 180 ° ± 20 °) with respect to the exposure light and a function of transmitting a part of the exposure light. The transmittance of exposure light is set to a predetermined value of 1% to 80%, usually 3% to 40%, depending on the pattern transfer application. As a material of the phase shift film, a chromium compound material such as chromium oxycarbide (CrOC), chromium oxynitride (CrON), chromium oxycarbonitride (CrOCN), chromium nitride (CrN), or molybdenum such as MoSi A material such as molybdenum silicide oxide (MoSiO), molybdenum silicide oxynitride (MoSiON), and molybdenum silicide nitride (MoSiN) containing oxygen and nitrogen in molybdenum silicide mainly composed of a silicon compound and silicon is preferably used. be able to.
In the case of a mask blank (phase shift mask blank) used for a halftone phase shift mask, a light shielding film may be formed in addition to the phase shift film.

  A mask blank is manufactured by performing up to the thin film forming step.

  According to the mask blank of the second embodiment, a thin film serving as a transfer pattern is formed on the first main surface of the mask blank substrate of the first embodiment. Thereby, the mask blank of Embodiment 2 has a high manufacturing yield.

Embodiment 3 FIG.
In Embodiment 3, a mask for manufacturing a display device and a manufacturing method thereof will be described.

<Mask>
The mask according to the third embodiment includes a mask blank substrate including a light-transmitting substrate and a thin film having a transfer pattern formed on the first main surface of the light-transmitting substrate. The translucent substrate has a mark that identifies the first main surface. The mark is provided on at least one of the first main surface, the second main surface, and the end surface. The mark can be removed by mirror polishing of the first main surface and the second main surface, and at least one of roughening processing of the end surface and mirror polishing.
Details of the translucent substrate and the mark are as described above.

<Manufacturing method of mask>
The mask manufacturing method according to the third embodiment prepares a mask blank including a mask blank substrate including a translucent substrate and a thin film serving as a transfer pattern formed on the first main surface of the translucent substrate. And a step of forming a transfer pattern on the thin film. The translucent substrate has a mark that identifies the first main surface. The mark is provided on at least one of the first main surface, the second main surface, and the end surface. The mark can be removed by mirror polishing of the first main surface and the second main surface, and at least one of roughening processing of the end surface and mirror polishing.
Details of the translucent substrate and the mark are as described above.
Details of the mask manufacturing method of the third embodiment will be described below.

(Mask blank preparation process)
First, the mask blank manufactured in the second embodiment is prepared. At this time, if the resist film is not formed on the mask blank, the resist film is formed on the mask blank. Here, the resist film is composed of a positive photoresist material or a negative photoresist material, and is formed using, for example, a slit coater or a spin coater.

(Transfer pattern formation process)
Subsequently, a desired pattern is drawn and exposed on the resist film using a laser drawing machine or the like, and development is performed by a technique such as a spray method to form a resist film pattern.
Then, using the formed resist film pattern as a mask, the thin film is etched to form a transfer pattern. For etching the thin film, for example, when the thin film is made of a Cr-based material, an etching solution for chromium containing cerium diammonium nitrate and perchloric acid is used. When the thin film is made of a MoSi-based material, an etching solution containing ammonium hydrogen fluoride and hydrogen peroxide is used.
Thereafter, the resist film pattern is removed using a stripping solution or the like. Note that the upper surface of the manufactured transfer pattern is preferably covered with a pellicle.

  A mask is manufactured by performing the transfer pattern forming process.

  According to the mask of the third embodiment, the transfer pattern is formed on the first main surface of the mask blank substrate of the first embodiment. Thereby, the mask of Embodiment 3 has a high manufacturing yield.

  Hereinafter, based on an Example and a comparative example, this invention is demonstrated more concretely. The following examples are merely examples of the present invention and do not limit the present invention.

  In Examples 1 to 5 and Comparative Example 1, the case where the translucent substrate is a glass substrate made of synthetic quartz glass and the thin film formed on the translucent substrate is a phase shift film made of a chromium-based material is described. To do. The present invention can be similarly applied to other combinations of translucent substrates and thin films.

Example 1.
The mask blank substrate for manufacturing the display device of Example 1 was manufactured by the following method. The specification of the mask blank substrate for manufacturing the display device of Example 1 is that the thin film is formed with a flatness of 7 μm or less and a parallelism of 10 μm or less on the side on which the thin film is formed (first main surface). The defect quality on the side (first main surface) was determined to be no defect of 2 μm or more.

<< Glass substrate preparation process >>
First, a surface obtained by cutting a synthetic quartz glass ingot into a substrate shape was subjected to surface grinding of one main surface and the other main surface, and chamfering using # 1200 diamond abrasive grains, and 800 mm A glass substrate made of 8092 size synthetic quartz glass of × 920 mm × 10 mm was obtained. The obtained glass substrate had no notch mark formed on both main surfaces.

<< Substrate thickness inspection process >>
One main surface and the other main surface of the glass substrate subjected to the cleaning treatment were measured with a flatness tester manufactured by Kuroda Seiko Co., Ltd. to obtain surface morphology information.
This surface form information is information indicating the unevenness of both main surfaces, and is height information of each measurement point on both main surfaces with respect to a virtual absolute plane obtained by measuring an area excluding the outer circumference of 5 mm on both main surfaces at intervals of 10 mm. .
Based on the obtained surface morphology information, the plate thickness of the glass substrate was calculated including the variation in the plate thickness.
The thickness specification of the 8092 size photomask substrate is 10 mm ± 0.2 mm. In consideration of the lower limit of the plate thickness specification (9.8 mm) and the polishing allowance in the subsequent polishing step, it was inspected whether the minimum plate thickness of the glass substrate had a thickness of 9.9 mm or more.
As a result of the inspection, it was confirmed that the minimum plate thickness exceeded 9.9 mm and had a polishing allowance necessary for obtaining the required surface roughness.

<< Scratch defect inspection process >>
Thereafter, the presence or absence of scratches on both main surfaces of the glass substrate was inspected by visual inspection. Empirically, a flaw having a depth of 20 μm or more can be detected (confirmed) by visual inspection. When the obtained glass substrate was inspected, scratches that could be detected by visual inspection could not be confirmed on both main surfaces.

<< Flatness calculation process >>
The flatness of both main surfaces was calculated based on the obtained surface morphology information.
As a result of calculating the flatness of both main surfaces, one main surface was 22.5 μm and the other main surface was 8.5 μm.

<< Local wet etching process >>
Next, based on the surface morphology information (position information and height information with respect to the reference surface) of the two main surfaces acquired previously, a region that is relatively convex beyond at least the permissible value is hooked. Local wet etching with an acid aqueous solution was performed.

As a result, the flatness of one main surface was 5.4 μm.
In addition, the surface roughness by local wet etching was not confirmed.
The local wet etching can reduce a load of a polishing process performed thereafter while suppressing a polishing allowance.

<< Mirror polishing process >>
The mirror polishing step here includes a first polishing step, a post-polishing surface form information acquisition step, a post-polishing flatness calculation step, a second polishing step, and a third polishing step.

<<< First Polishing Step >>>
In the first polishing step, both main surfaces of the first main surface and the second main surface of the glass substrate were polished using a double-side polishing apparatus for the purpose of eliminating minute scratches that are difficult to visually confirm. Here, the polishing conditions were as follows.
Polishing conditions:
Polishing liquid: Cerium oxide (average particle size: 1 μm) Free abrasive grains with water added to abrasive grains Polishing cloth: Hard polisher Surface plate rotation speed: 1 to 30 rpm (rotates clockwise as viewed from the top of the double-side polishing apparatus)
Lower platen rotation speed: 1 to 30 rpm (rotates counterclockwise when viewed from the top of the double-side polishing machine)
Pressure: 80-100 g / cm ²
After the first polishing step was completed, the glass substrate was cleaned with a chemical solution using a low-concentration alkaline aqueous solution, and then the glass substrate was cleaned with pure water.

<<< Surface shape information acquisition process after polishing >>>
In the post-polishing surface form information acquisition step, surface form information was acquired for both main surfaces of the glass substrate that had been subjected to chemical cleaning and pure water cleaning after the first polishing step.
This surface form information is information indicating the unevenness of both main surfaces. Specifically, the height information of each measurement point with respect to the virtual absolute plane is measured at 10 mm intervals in the area excluding the outer circumference of 5 mm on both main surfaces. It is.
In addition, Kuroda Seiko Co., Ltd. flatness tester was used as a measuring instrument used for acquisition of surface form information.

<<< Post-polishing flatness calculation step >>>
In the post-polishing flatness calculation step, the flatness of both main surfaces is calculated from the surface shape information of both main surfaces obtained in the post-polishing surface shape information acquisition step using a computer, and the parallelism of the glass substrate is also calculated. Calculated.
As a result, the flatness of one main surface was 6.1 μm, the flatness of the other main surface was 9.4 μm, and the parallelism of the glass substrate was 10.8 μm.

<<< Second Polishing Step >>>
In the second polishing step, the processing conditions of the single-side polishing apparatus having different processing amounts in the plane of the other main surface so that the flatness of the other main surface is 7 μm or less and the parallelism of the glass substrate is 10 μm or less. Was determined, and single-side polishing was performed on the other main surface.
The polishing conditions are as follows.
Polishing conditions:
Polishing liquid: Cerium oxide (average particle size: 1 μm) Free abrasive grains with water added to abrasive grains Polishing cloth: Soft polisher Number of rotations of substrate holding plate: 3 to 20 rpm (counterclockwise when viewed from the top surface of the substrate holding plate) rotation)
Number of rotations of polishing platen: 3 to 20 rpm (rotates clockwise as viewed from the top surface of the substrate holding plate)
After the second polishing step was completed, the glass substrate was cleaned with a chemical solution using a low-concentration alkaline aqueous solution, and then the glass substrate was cleaned with pure water.

<<< Third polishing step >>>
In the third polishing step (precision polishing step), both surfaces of the glass substrate were polished using a double-side polishing apparatus for the purpose of increasing the smoothness of both main surfaces. The polishing conditions are as follows.
Polishing conditions:
Polishing liquid: Colloidal silica (average particle diameter: 50 to 80 nm) Free abrasive grains in which water is added to abrasive grains Polishing cloth: Soft polisher Upper platen rotation speed: 1 to 30 rpm (Rotate clockwise as viewed from the upper surface of the double-side polishing apparatus) )
Lower platen rotation speed: 1 to 30 rpm (rotates counterclockwise when viewed from the top of the double-side polishing machine)
Pressure: 80-100 g / cm ²
After the third polishing step was completed, the glass substrate was cleaned with a chemical solution using a low-concentration alkaline aqueous solution, and then washed with pure water.

<< Surface flatness / parallelism, surface roughness, defect inspection >>
Surface morphology information of both main surfaces was acquired for the glass substrates after chemical cleaning and pure water cleaning were performed after the third polishing step. Then, the flatness of both main surfaces was calculated from the obtained surface morphology information, and the parallelism was calculated.
As a result, the flatness of one main surface was 6.1 μm, the flatness of the other main surface was 8.8 μm, and the parallelism was 7.7 μm. In addition, when defects on both main surfaces of the glass substrate were inspected by a defect inspection apparatus, defects of 2 μm or more were not detected. Moreover, when the surface roughness of both the main surfaces of the glass substrate was measured with the surface roughness measuring instrument, the surface roughness of both the main surfaces was both 0.2 nm in Ra. Based on the inspection result, for the glass substrate, one main surface described above was used as a first main surface on which a thin film serving as a transfer pattern was formed, and the other main surface was used as a second main surface.
The obtained glass substrate has a flatness of the first main surface of 7 μm or less, a parallelism of 10 μm or less, and no defects of 2 μm or more are present on the first main surface, thereby forming a high-definition pattern. The specification of a mask blank substrate suitable for manufacturing a mask or the like for satisfying the requirements was satisfied.

<< Mark formation process >>
One of the marks shown in FIGS. 1 to 7 for specifying the first main surface of the glass substrate was formed on the seven glass substrates obtained by the same procedure as described above.
FIG. 1 shows a first example of a mark. This mark is composed of a rough surface portion 11 provided at a corner portion of the outer peripheral region of the second main surface 10 of the glass substrate. This mark was formed by applying a hydrofluoric acid aqueous solution to the corners of the second outer peripheral region of the glass substrate, leaving it for a predetermined time, washing the glass substrate, and removing the etching solution. The surface roughness of the rough surface portion 11 was 0.07 μm in Ra. The rough surface portion can also be formed on the first main surface.
FIG. 2 shows a second example of the mark. This mark is composed of a mirror surface portion 21 provided on the end surface 20 of the glass substrate. The end surface 20 of the glass substrate forming this mark is # 1200 diamond abrasive grains after the local wet etching process and before the mirror polishing process of the first main surface and the second main surface of the glass substrate. A roughening treatment was performed by chamfering using sapphire. The surface roughness of the surface roughening treatment part 22 other than the mirror surface part 21 was 0.11 μm in terms of Ra. The mark composed of the mirror surface portion 21 was formed by partial mirror polishing using a cylindrical rotary processing tool with a polishing pad and a cerium oxide slurry. The surface roughness of the mirror surface portion 21 was 0.01 μm in Ra. In the example of FIG. 2, the mirror surface portion 21 has a trapezoidal shape that is wide on the second main surface 10 side and narrow on the first main surface 30 side, but may be vice versa.
FIG. 3 shows a third example of the mark. This mark is composed of a rough surface portion 23 provided on the end surface 20 of the glass substrate. The end surface 20 of the glass substrate that forms this mark is a cerium oxide slurry after the local wet etching process and before the mirror polishing process of the first main surface and the second main surface of the glass substrate. The mirror surface was polished by brush polishing. The surface roughness of the mirror-polished portion 24 other than the rough surface portion 23 that was mirror-polished was 0.01 μm in Ra. The mark composed of the rough surface portion 23 was formed by sandblasting. The surface roughness of the rough surface portion 23 was 0.012 μm in Ra. In the example of FIG. 3, the rough surface portion 23 has a trapezoidal shape that is wide on the second main surface 10 side and narrow on the first main surface 30 side, but may be reversed.
FIG. 4 shows a fourth example of the mark. This mark is comprised from the marker part 12 containing the water-based dye or water-based pigment attached to the corner | angular part of the outer peripheral area | region of the 2nd main surface 10 of a glass substrate. The marker portion 12 was formed with a sign pen. The marker part can also be formed on the end face.
FIG. 5 shows a fifth example of the mark. This mark is composed of a recess 13 provided at a corner of the outer peripheral region of the second main surface 10 of the glass substrate. This mark was formed by pressing marks scanned by a diamond needle. The depth of the recess 13 was 2.2 μm. The concave portion can also be formed on the first main surface or the end surface.
FIG. 6 shows a sixth example of the mark. This mark is composed of a laser marking 14 provided at a corner of the outer peripheral region of the second main surface 10 of the glass substrate. This mark was formed using the fourth harmonic (wavelength 266 μm) of the YAG laser. This mark was formed by forming eight laser markings 14 having a circular shape with a diameter of 10 μm and a depth of 3.3 μm in a cross shape. This laser marking can also be formed on the first main surface.
FIG. 7 shows a seventh example of the mark. This mark is composed of a laser marking 25 provided on the end face 20 of the glass substrate. This mark was formed using the fourth harmonic (wavelength 266 μm) of the YAG laser. This mark was formed by forming eight laser markings 25 having a circular shape with a diameter of 10 μm and a depth of 3.3 μm in a trapezoidal shape at positions shifted from the center position in the thickness direction of the end face. In the example of FIG. 7, the surface close to the side on which the laser marking 25 is formed is the second main surface 10, but the opposite may be possible.

  After the marks shown in FIGS. 1 to 7 were formed, the flatness and parallelism of the seven glass substrates were calculated by the same method as described above. The glass substrate on which the mark shown in FIGS. 1 to 7 was formed maintained the flatness and parallelism before formation, and the manufacturing yield by the mark formation shown in FIGS. 1 to 7 was 100%.

Example 2
The mask blank substrate for manufacturing the display device of Example 2 was manufactured by the following method.
In Example 2, a case where a mask blank substrate is manufactured by recycling a glass substrate from a used mask (for example, the mask of Example 4) manufactured using the mask blank substrate of Example 1 will be described. . The specifications of the mask blank substrate for manufacturing the display device of Example 2 are such that the thin film is formed with a flatness of 7 μm or less and a parallelism of 10 μm or less on the side on which the thin film is formed (first main surface). The defect having a defect quality of 2 μm or more on the side (first main surface) was not present.

First, a chromium-based substrate is used on 70 mask blank substrates of Example 1 in which the marks of FIGS. 1 to 7 are formed (10 mask blank substrates on which the marks of FIGS. 1 to 7 are formed). A used mask on which a phase shift film pattern made of a material was formed was prepared.
Next, the phase shift film pattern was removed with an etching solution for chromium containing ceric ammonium nitrate, perchloric acid and pure water to obtain a glass substrate. At this stage, the glass substrate obtained by recycling the mask manufactured using the glass substrate on which the marks shown in FIGS. 1 to 3 and FIGS. Are formed. Since the marks shown in FIG. 4 are removed when the glass substrate is washed in the mask blank manufacturing process, the glass obtained by recycling the mask manufactured using the glass substrate on which the marks shown in FIG. 4 are formed. The mark shown in FIG. 4 is not formed on the substrate.

  After removing the phase shift film pattern with the chromium etching solution, a mask blank substrate was manufactured in the same procedure as in Example 1 for the cleaned glass substrate.

The marks shown in FIGS. 1, 5, and 6 formed on the glass substrate obtained by recycling the mask manufactured using the glass substrate on which the marks shown in FIGS. Removed by.
The mark shown in FIG. 2 formed on the glass substrate obtained by recycling the mask manufactured using the glass substrate on which the mark shown in FIG. 2 is formed is formed with an end face mark after the mirror polishing process. The part which has been removed was removed by rough polishing or sandblasting.
The mark shown in FIG. 3 formed on the glass substrate obtained by recycling the mask manufactured using the glass substrate on which the mark shown in FIGS. 3 and 7 is formed is the mark on the end face after the mirror polishing step. The formed part was removed by partial mirror polishing using a rotary processing tool.

Similarly to Example 1, surface morphology information of both main surfaces was obtained for 70 glass substrates after chemical cleaning and pure water cleaning after the third polishing step, and the obtained surface morphology information. As well as calculating the flatness of both main surfaces, the parallelism was calculated.
As a result, the flatness of one main surface was in the range of 5 to 20 μm, the flatness of the other main surface was in the range of 5 to 12 μm, and the parallelism was in the range of 7 to 18 μm. In addition, when defects on both main surfaces of the glass substrate were inspected by a defect inspection apparatus, no defects of 2 μm or more were detected on the first main surface and the second main surface with good flatness. Moreover, when the surface roughness of both main surfaces of the glass substrate was measured with a surface roughness measuring instrument, the surface roughness of both the first main surface and the second main surface was 0.3 nm or less in Ra. . In Example 2, the first main surface was a surface on which a thin film serving as a transfer pattern was formed even before recycling, and the second main surface was the back surface even before recycling.

  The glass substrate obtained by recycling the mask manufactured using the glass substrate on which the mark shown in FIG. 1 to FIG. 7 is formed has no mark at the stage before the mark forming process. On the glass substrate, any mark shown in FIG. 1 to FIG. 7 that specifies the surface having good flatness as the first main surface was formed in the mark forming step. The manufacturing yield of the mask blank substrate satisfying the specifications that the flatness (first main surface) on which the thin film is formed is 7 μm or less and the parallelism is 10 μm or less was 97%.

  After any of the marks shown in FIGS. 1 to 7 was formed again, the flatness and parallelism of the glass substrate were calculated in the same manner as described above. The glass substrate on which the mark shown in FIGS. 1 to 7 was formed maintained the flatness and parallelism before formation, and the manufacturing yield by the mark formation shown in FIGS. 1 to 7 was 100%.

Example 3
In Example 3, using the mask blank substrate obtained in Example 2, a phase shift mask blank, which is a photomask blank, was produced by the following method.

First, the mask blank substrate obtained in Example 2 was cleaned with a chemical solution using a low-concentration alkaline aqueous solution, and then washed with pure water. The marks shown in FIG. 4 were removed by this cleaning.
Next, the first main surface of the mask blank substrate was set to face the sputtering target surface installed in the sputtering apparatus. Then, a phase shift film was formed on the first main surface of the mask blank substrate by sputtering.

Specifically, first, a mixed gas composed of Ar gas, N ₂ gas and CO ₂ gas is introduced into a sputtering chamber of a sputtering apparatus in which a chromium target is disposed, and a film thickness of 89 nm composed of CrOCN is formed by reactive sputtering. The phase shift layer was formed. Here, the flow rate of each component constituting this mixed gas is 35 sccm for Ar, 35 sccm for N ₂ , and 14.5 sccm for CO ₂ .
Next, a mixed gas of Ar gas and CH ₄ gas was introduced into the sputtering chamber in which the chromium target was placed, and a 10 nm-thick metal layer made of CrC was formed by reactive sputtering. Here, this mixed gas is a mixed gas containing 8% concentration of CH ₄ gas in Ar gas.

Finally, a mixed gas composed of Ar gas, N ₂ gas and CO ₂ gas is introduced into the sputtering chamber in which the chromium target is disposed, and a 30 nm-thickness reflection reduction layer composed of CrOCN is formed by reactive sputtering. did. Here, the flow rate of each component constituting this mixed gas is 35 sccm for Ar, 35 sccm for N ₂ , and 18.2 sccm for CO ₂ .
As a result, a phase shift layer composed of a 89 nm thick CrOCN phase shift layer, a 10 nm thick CrC metal layer, and a 30 nm thick CrOCN reflection reduction layer is formed on the substrate. A shift mask blank was obtained.

The phase shift film formed as described above has a transmittance of 5.98% for light of 365 nm and a phase difference of 178.66 ° due to the three-layer structure of the phase shift layer, the metal layer, and the reflection reduction layer. Was. Here, the transmittance and the phase difference were measured using MPM-100 (trade name) manufactured by Lasertec Corporation.
Further, the flatness of the main surface on the side where the thin film of the obtained phase shift mask blank is formed depends on the flatness of the first main surface of the mask blank substrate obtained in Example 2, The value was 10 μm or less.
Further, the parallelism of the obtained phase shift mask blank also depends on the parallelism of the mask blank substrate obtained in Example 2, and its value was 12 μm or less.

The phase shift mask blank manufactured by the above process has a flatness of the main surface on the side on which the thin film is formed of 10 μm or less and a parallelism of 12 μm or less. Suitable for
In particular, a phase shift mask in which a line and space pattern of 2.0 μm or less (for example, 1.2 μm to 2.0 μm) or a hole pattern of 2.0 μm or less (for example, 1.5 to 2.0 μm) is formed. Suitable for manufacturing.
This phase shift mask is applied to manufacture of a high-resolution display panel (liquid crystal panel or organic EL panel) having a resolution exceeding 500 ppi (for example, 600 ppi or more).

Example 4
In Example 4, a photomask (phase shift mask) was manufactured by the following method using the phase shift mask blank manufactured in Example 3.
First, a resist film made of a novolak positive photoresist was formed on the phase shift film of the phase shift mask blank manufactured in Example 3. Thereafter, a predetermined pattern was drawn on the resist film using a laser beam with a wavelength of 413 nm by a laser drawing machine. Thereafter, the resist film was developed with a predetermined developer to form a resist film pattern on the phase shift film.
Then, the phase shift film pattern was formed by etching the phase shift film using the resist film pattern as a mask.

Each of the phase shift layer, the metal layer, and the reflection reduction layer constituting the phase shift film is formed of a chromium-based material containing chromium (Cr). For this reason, the phase shift layer, the metal layer, and the reflection reducing layer can be etched with the same etching solution.
Here, an etching solution for chromium containing ceric ammonium nitrate and perchloric acid was used as an etching solution for etching the phase shift film.
Then, the mask for exposure was obtained by peeling a resist film pattern using resist stripping solution.

Since pattern drawing is performed on a substrate having high flatness, the CD (Critical Dimension) variation of the phase shift film pattern was as good as 70 nm. Here, the CD variation is a deviation width from a target line-and-space pattern (line pattern width: 2.0 μm, space pattern width: 2.0 μm). The CD variation of the phase shift film pattern was measured using SIR8000 manufactured by Seiko Instruments Nano Technology Co., Ltd.
Since the above-described phase shift mask has flatness and parallelism that meet the required standards, and has excellent pattern cross-sectional shape and excellent CD uniformity, using the above-described phase shift mask, high resolution, It can be said that a high-definition display device (organic EL panel) can be manufactured.

Example 5 FIG.
In Example 5, as in Example 2, a case where a mask blank substrate is manufactured by recycling a glass substrate from a used mask manufactured using a mask blank substrate will be described.
The mask blank substrate for manufacturing the display device of Example 5 was manufactured by the following method.

First, a used mask in which a phase shift film pattern made of a chromium-based material was formed on a mask blank substrate was prepared. On these glass substrates, 1.0 to 2.0 mm of notch marks were formed at two positions opposite to the end on the back surface before recycling.
As described above, the notch mark causes the occurrence of edge sag and bulge. Therefore, when manufacturing a mask for forming a high-definition pattern, a mask blank substrate having no notch mark is used. Is preferred. However, there is a need to use a substrate with notch marks already formed as a recycled product, and a mask blank substrate for a middle layer or rough layer, or a mask blank substrate for a color filter, The required accuracy is relaxed compared to the above-mentioned high-definition one.
Considering these points, the first specification (specification suitable for manufacturing a high-definition phase shift mask or the like) of the mask blank substrate for manufacturing the display device of Example 5 is a thin film as in Example 2. There is no defect with a flatness of 7 μm or less, parallelism of 10 μm or less on the side where the film is formed (first main surface), and a defect quality of 2 μm or more on the side where the thin film is formed (first main surface) It was. The second specification (middle layer or rough layer specification) has a flatness of the first main surface of 10 μm or less, a parallelism of 20 μm or less, and a defect quality of the first main surface of 5 μm or more. It was decided that there were no defects.
Next, the phase shift film pattern was removed with an etching solution for chromium containing ceric ammonium nitrate, perchloric acid and pure water to obtain a glass substrate.
After removing the phase shift film pattern with the etching solution for chromium, the glass substrate that has been subjected to the cleaning treatment is subjected to <substrate plate thickness inspection step><scratch defect inspection step><flatness calculation step> in the same manner as in Example 1. It was.

As a result, it was confirmed that the minimum plate thickness exceeded 9.9 mm and had a polishing allowance necessary for obtaining the required surface roughness.
Moreover, about the presence or absence of the damage | wound in both the main surfaces of a glass substrate, it was confirmed that the damage | wound which can be detected by visual inspection is formed in the front and back.
The flatness of both main surfaces was 10 μm on one main surface and 12 μm on the other main surface.
Next, the notch mark of the same magnitude | size was formed in the position of one main surface facing the notch mark currently formed in the other main surface of the glass substrate. In the fifth embodiment, the notch mark corresponding to the notch mark already formed on the other main surface is formed on the one main surface, thereby suppressing the occurrence of the bulge, which has been a problem in the past. Then, in the same manner as in Example 1, after performing the <second polishing step> and the <third polishing step> among the <local wet etching step> and the <mirror polishing step>, and after the third polishing step is completed, the glass The substrate was washed with a chemical solution using a low-concentration alkaline aqueous solution, and then washed with pure water.

The surface morphology information of both main surfaces was acquired for the obtained glass substrate. Then, the flatness of both main surfaces was calculated from the obtained surface morphology information, and the parallelism was calculated.
As a result, the flatness of the one main surface was 9.8 μm, the flatness of the other main surface was 6.9 μm, and the parallelism was 9.9 μm. In addition, when defects on both main surfaces of the glass substrate were inspected by a defect inspection apparatus, defects of 2 μm or more were not detected. Further, when the surface roughness of both main surfaces of the glass substrate was measured by a surface roughness measuring instrument, the surface roughness of the one main surface and the other main surface was Ra of 0.2 nm.

Based on these inspection results, in this glass substrate, the other main surface used as the back surface before recycling is set as the first main surface on which a thin film to be a transfer pattern is formed. One main surface used as a second main surface was set. The obtained glass substrate has a flatness of the other main surface of 7 μm or less, a parallelism of 10 μm or less, and no defects of 2 μm or more are present on the second main surface, so that a high-definition pattern is formed. Therefore, the specification of a mask blank substrate suitable for manufacturing a mask for the purpose was satisfied.
Next, the mark shown in FIG. 3 for specifying the first main surface was formed to obtain a mask blank substrate.

Next, in the same manner as in Example 3, a phase shift mask blank was produced. In the obtained phase shift mask blank, the flatness of the main surface on the side where the thin film was formed was 10 μm or less, and the parallelism was 12 μm or less.
Further, a phase shift mask was produced in the same manner as in Example 4. The CD variation of the obtained phase shift film pattern was as good as 76 nm. The phase shift mask of Example 5 has flatness and parallelism satisfying the required level, has excellent CD uniformity, and manufactures a high-resolution, high-definition display device (organic EL panel). Can be said.
About 70 glass substrates manufactured by the manufacturing method demonstrated above, the surface form information of both main surfaces was acquired, and the flatness and parallelism of both main surfaces were computed from the obtained surface form information. As a result, the flatness of one main surface was in the range of 5 to 30 μm, the flatness of the other main surface was in the range of 5 to 20 μm, and the parallelism was in the range of 7 to 30 μm. The manufacturing yield of the mask blank substrate that satisfies the first specification described above and that is suitable for manufacturing a mask for forming a high-definition pattern is 87%, which is a good value although lower than that of the first embodiment. It was. Further, the manufacturing yield of the mask blank substrate for the middle layer and the rough layer that satisfies the second specification described above was 94%, which was a further favorable value.

  In the fifth embodiment, the case where the notch marks are formed on both the first main surface and the second main surface is described, but the present invention is not limited to this. When it is determined that local processing is unnecessary by the <substrate plate thickness inspection process> <scratch defect inspection process> <flatness calculation process> on both main surfaces of the glass substrate after the phase shift film pattern is peeled off Depending on the situation such as being used for a layer, a mark of this example for specifying a surface satisfying specifications of flatness and defect quality may be formed on a glass substrate having a notch mark formed on only one side. Also good.

Comparative Example 1
Comparative Example 1 is an example of manufacturing a mask blank substrate by forming a conventional notch mark on a glass substrate instead of the mark forming step of Example 1. The notch marks were formed in a size of 1.0 to 2.0 mm at two end portions of the second main surface of the glass substrate. Then, the first specification and the second specification of Comparative Example 1 were set in the same manner as in Example 5.
70 steps of mask blank substrates were manufactured in the same manner as in Example 1 until << surface flatness / parallelism, surface roughness, defect inspection >> after the third polishing step (precision polishing step).

  After forming the notch mark, the flatness and parallelism of the glass substrate were calculated by the same method as described above. As a result, the flatness of the first main surface on which the notch mark is not formed is 7 μm or less, the parallelism is 10 μm or less, and the defect quality of the first main surface is 2 μm or more. The manufacturing yield of a mask blank substrate suitable for manufacturing a mask or the like for forming a high-definition pattern that satisfies the above specifications was 20%. Further, the manufacturing yield of the mask blank substrate for the middle layer and rough layer satisfying the second specification was 37%.

DESCRIPTION OF SYMBOLS 10 2nd main surface, 11 Rough surface part, 12 Marker part, 13 Recessed part, 14 Laser marking, 20 End surface, 21 Mirror surface part, 22 Roughening process part, 23 Rough surface part, 24 Mirror surface polishing part, 25 Laser marking, 30 First major surface.

Claims (16)

In a mask blank substrate for manufacturing a display device,
A first main surface on which a thin film to be a transfer pattern is formed; a second main surface provided opposite to the first main surface; the first main surface and the second main surface; A translucent substrate having an end surface perpendicular to the
The translucent substrate has a mark that identifies the first main surface;
The mark is provided on at least one of the first main surface, the second main surface, and the end surface,
The mark can be removed by at least one of mirror polishing of the first main surface and the second main surface, surface roughening and mirror polishing of the end surface, and cleaning of the translucent substrate. A mask blank substrate characterized by the above. The mark includes a rough surface portion provided in an outer peripheral region of the first main surface or the second main surface,
The rough surface portion has a roughness that can be discerned visually or by a difference in optical characteristics between the mark and other regions, and the first main surface or the second surface on which the mark is formed. 2. The mask blank substrate according to claim 1, which has a roughness that can be removed by mirror polishing of the main surface.   3. The mask blank substrate according to claim 2, wherein the mark is provided at a corner portion of the first main surface or the second main surface. The mark includes a mirror surface portion provided on the end surface;
The mirror surface portion has a roughness that can be identified by visual observation or a difference in optical characteristics between the mark and the other region, and can be removed by a roughening treatment of the end surface. The mask blank substrate according to any one of claims 1 to 3. The mark includes a rough surface portion provided on the end surface,
The rough surface portion has a roughness that can be discerned visually or by a difference in optical characteristics between the mark and other regions, and has a roughness that can be removed by mirror polishing of the end surface. The mask blank substrate according to any one of claims 1 to 3. The mark includes a marker portion containing a water-based dye or a water-based pigment provided on an outer peripheral region or the end surface of the second main surface,
6. The mask blank substrate according to claim 1, wherein the marker portion can be removed by cleaning the translucent substrate.   7. The mask blank substrate according to claim 1, wherein the translucent substrate is a recycled product obtained by removing a thin film on which a transfer pattern is formed from a used mask. . In a method for manufacturing a mask blank substrate for manufacturing a display device,
A first main surface on which a thin film to be a transfer pattern is formed; a second main surface provided opposite to the first main surface; the first main surface and the second main surface; Providing a translucent substrate having an end face perpendicular to the surface;
Mirror polishing the first main surface and the second main surface of the translucent substrate;
Forming a mark that identifies the first main surface on at least one of the first main surface, the second main surface, and the end surface after the mirror polishing, and
The mark can be removed by at least one of mirror polishing of the first main surface and the second main surface, surface roughening and mirror polishing of the end surface, and cleaning of the translucent substrate. A method for manufacturing a mask blank substrate.   The method of manufacturing a mask blank substrate according to claim 8, further comprising a step of roughening the end face before forming the mark.   The method for manufacturing a mask blank substrate according to claim 8, further comprising a step of mirror polishing the end face before forming the mark. Obtaining at least one surface information of flatness, surface roughness, and defect information of the first main surface and the second main surface after the mirror polishing,
The method for manufacturing a mask blank substrate according to claim 8, wherein the mark is formed according to the surface information.   12. The mask blank substrate according to claim 8, wherein the translucent substrate is a recycled product obtained by removing a thin film on which a transfer pattern is formed from a used mask. Manufacturing method. In mask blanks for manufacturing display devices,
A first main surface on which a thin film to be a transfer pattern is formed; a second main surface provided opposite to the first main surface; the first main surface and the second main surface; A mask blank substrate including a translucent substrate having an end surface perpendicular to the substrate;
A thin film serving as a transfer pattern formed on the first main surface of the translucent substrate,
The translucent substrate has a mark that identifies the first main surface;
The mark is provided on at least one of the first main surface, the second main surface, and the end surface,
The mask blank, wherein the mark can be removed by at least one of a mirror polishing of the first main surface and the second main surface, and a roughening process and a mirror polishing of the end face. In a method for manufacturing a mask blank for manufacturing a display device,
A first main surface on which a thin film to be a transfer pattern is formed; a second main surface provided opposite to the first main surface; the first main surface and the second main surface; Providing a mask blank substrate including a translucent substrate having an end surface perpendicular to the surface;
Cleaning the mask blank substrate;
Forming a thin film to be a transfer pattern on the first main surface of the translucent substrate after cleaning, and
The translucent substrate has a mark that identifies the first main surface;
The mark is provided on at least one of the first main surface, the second main surface, and the end surface,
The mark can be removed by at least one of mirror polishing of the first main surface and the second main surface, surface roughening and mirror polishing of the end surface, and cleaning of the translucent substrate. A method of manufacturing a mask blank characterized by the above. In a mask for manufacturing a display device,
A first main surface on which a thin film to be a transfer pattern is formed; a second main surface provided opposite to the first main surface; the first main surface and the second main surface; A mask blank substrate including a translucent substrate having an end surface perpendicular to the substrate;
A thin film having a transfer pattern formed on the first main surface of the translucent substrate,
The translucent substrate has a mark that identifies the first main surface;
The mark is provided on at least one of the first main surface, the second main surface, and the end surface,
The mark can be removed by at least one of a mirror polishing of the first main surface and the second main surface, and a roughening process and a mirror polishing of the end face. In a manufacturing method of a mask for manufacturing a display device,
A first main surface on which a thin film to be a transfer pattern is formed; a second main surface provided opposite to the first main surface; the first main surface and the second main surface; A mask blank including a light-transmitting substrate having an end surface perpendicular to the light-transmitting substrate and a thin film serving as a transfer pattern formed on the first main surface of the light-transmitting substrate is prepared. Process,
Forming a transfer pattern on the thin film,
The translucent substrate has a mark that identifies the first main surface;
The mark is provided on at least one of the first main surface, the second main surface, and the end surface,
The mark can be removed by at least one of mirror polishing of the first main surface and the second main surface, and roughening processing of the end surface and mirror polishing. .

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