Photomask blanks and photomasks

Abstract

Provided is a photomask blank comprising a transparent substrate, and a light-blocking film disposed on one surface of the transparent substrate and including a chromium-based material, wherein the sheet resistance of the light-blocking film is 103-107 Ω / □.

Description

[Technical field]

[0001] The present disclosure relates to photomask blanks and photomasks. [Background technology]

[0002] Photolithography technology is widely used in the manufacture of semiconductor devices, display devices, etc. Photomasks used in photolithography have a problem of electrostatic breakdown (also called discharge breakdown).

[0003] As a countermeasure against electrostatic breakdown, for example, a method of forming a conductive layer between a transparent substrate and a light-shielding pattern in a photomask having a light-shielding pattern on a transparent substrate has been proposed. In this method, the electrostatic breakdown can be suppressed by reducing the potential difference between adjacent light-shielding patterns by the conductive layer. For example, Patent Document 1 discloses a photomask blank consisting of a light-transmitting substrate, an amorphous silicon film formed on the light-transmitting substrate, a conductive layer made of metal silicide formed on the amorphous silicon film, and a light-shielding metal layer formed on the conductive layer. Patent Document 2 discloses a photomask substrate having a glass substrate, in which an impurity-containing layer is formed on the glass substrate from a film-forming surface on which a light-shielding film is formed to a predetermined depth in the thickness direction of the glass substrate, and the impurity-containing layer contains an alkali metal and has electrical conductivity.

[0004] Patent Document 3 also proposes a photomask in which a picture portion is formed on one side of a transparent substrate by a plurality of figure patterns made of a light-shielding film having light-shielding properties against the exposure light during transfer, and in order to prevent discharge breakdown of two adjacent figure patterns due to discharge at the adjacent locations, a connecting line portion is arranged that is made of a first halftone film that is semi-transparent to the exposure light during transfer and has a line width that is not substantially resolved during transfer, and electrically connects the two figure patterns. In this method, the connecting line portion reduces the potential difference between adjacent light-shielding patterns, thereby suppressing electrostatic breakdown. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Unexamined Patent Publication No. 11749 / 1983 [Patent Document 2] JP 2014-21431 A [Patent Document 3] JP 2009-122295 A Summary of the Invention [Problem to be solved by the invention]

[0006] However, as described in Patent Documents 1 to 3, for example, when a conductive layer or a connection line portion is formed in a photomask, the manufacturing process of the photomask may become complicated and expensive.

[0007] The present disclosure has been made in consideration of the above-mentioned circumstances, and has as its main object to provide a photomask blank and a photomask capable of suppressing electrostatic breakdown. [Means for solving the problem]

[0008] In order to solve the above problems, the present disclosure provides a photomask blank having a transparent substrate and a light-shielding film that is disposed on one surface of the transparent substrate and contains a chromium-based material, the light-shielding film having a sheet resistance of 10 3 Ω / □ or more 10 7 To provide a photomask blank having a resistivity of Ω / □ or less.

[0009] In the photomask blanks of the present disclosure, the light-shielding film preferably has, in this order from the transparent substrate side, a light-shielding layer and a low-reflection layer.

[0010] In the photomask blanks of the present disclosure, the thickness of the light-shielding layer is preferably 100 nm or more and 200 nm or less.

[0011] In the photomask blanks of the present disclosure, the light-shielding layer preferably contains the chromium-based material containing oxygen.

[0012] In the photomask blanks of the present disclosure, the thickness of the light-shielding film is preferably 140 nm or more and 280 nm or less.

[0013] The present disclosure also provides a photomask having a transparent substrate and a light-shielding pattern that is disposed on one surface of the transparent substrate and contains a chromium-based material, the light-shielding pattern having a sheet resistance of 10 3 Ω / □ or more 10 7 To provide a photomask having a resistivity of Ω / □ or less.

[0014] In the photomask of the present disclosure, the light-shielding pattern preferably has, in this order from the transparent substrate side, a light-shielding layer and a low-reflection layer.

[0015] In the photomask of the present disclosure, the thickness of the light-shielding layer is preferably 100 nm or more and 200 nm or less.

[0016] In the photomask of the present disclosure, the light-shielding layer preferably contains the chromium-based material containing oxygen.

[0017] In the photomask of the present disclosure, the thickness of the light-shielding pattern is preferably 140 nm or more and 280 nm or less. Effect of the Invention

[0018] The present disclosure has an effect of providing a photomask blank and a photomask capable of suppressing electrostatic damage. [Brief description of the drawings]

[0019] [Figure 1] FIG. 1 is a schematic cross-sectional view illustrating a photomask blank of the present disclosure. [Diagram 2] FIG. 1 is a schematic cross-sectional view illustrating a photomask blank of the present disclosure. [Diagram 3] 1 is a schematic cross-sectional view illustrating a photomask of the present disclosure. [Figure 4] 1 is a schematic cross-sectional view illustrating a photomask of the present disclosure. [Diagram 5] 1 is a schematic plan view showing photomasks of an example and a comparative example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] The following describes the embodiments of the present disclosure with reference to the drawings. However, the present disclosure can be implemented in many different forms, and should not be interpreted as being limited to the description of the embodiments exemplified below. In addition, the drawings may be schematic in terms of the width, thickness, shape, etc. of each part compared to the actual form in order to make the explanation clearer, but these are merely examples and do not limit the interpretation of the present disclosure. In this specification and each figure, elements similar to those described above with respect to the previous figures may be given the same reference numerals, and detailed explanations may be omitted as appropriate.

[0021] In this specification, when describing a mode in which another component is disposed on a certain component, the term "above" or "below" is intended to include both a case in which another component is disposed directly above or below a certain component so as to be in contact with the component, and a case in which another component is disposed above or below a certain component with another component interposed therebetween, unless otherwise specified. Also, in this specification, when describing a mode in which another component is disposed on the surface of a certain component, the term "on the surface" is intended to include both a case in which another component is disposed directly above or below a certain component so as to be in contact with the component, and a case in which another component is disposed above or below a certain component with another component interposed therebetween, unless otherwise specified.

[0022] The photomask blanks and photomasks of the present disclosure will be described in detail below.

[0023] A. Photomask blanks The photomask blank in the present disclosure is a photomask blank having a transparent substrate and a light-shielding film that is disposed on one surface of the transparent substrate and contains a chromium-based material, and the light-shielding film has a sheet resistance of 10 3 Ω / □ or more 10 7 It is less than Ω / □.

[0024] Fig. 1 is a schematic cross-sectional view illustrating a photomask blank of the present disclosure. As shown in Fig. 1, the photomask blank 1 has a transparent substrate 2 and a light-shielding film 3 that is disposed on one surface of the transparent substrate 2 and contains a chromium-based material. The sheet resistance of this light-shielding film 3 is within a predetermined range. In the example shown in Fig. 1, the light-shielding film 3 has a light-shielding layer 3a and a low-reflection layer 3b in this order from the transparent substrate 2 side, but is not limited to this.

[0025] Here, the sheet resistance represents the electrical resistance of a thin film. For example, if the sheet resistance of a light-shielding film is high, it can be said that the electrical resistance of the light-shielding film is high.

[0026] According to the present disclosure, since the sheet resistance of the light-shielding film is high within the above range, when a photomask having a light-shielding pattern on one side of a transparent substrate is manufactured using the photomask blank of the present disclosure, when static electricity charged in the photomask is discharged, the current flowing through the light-shielding pattern can be reduced. In addition, the heat generated by the discharge current can be reduced. As a result, it is possible to suppress electrostatic breakdown.

[0027] Furthermore, according to the present disclosure, the sheet resistance of the light-shielding film can be adjusted by adjusting the composition of the light-shielding film, for example, including a chromium-based material. Therefore, by using the photomask blanks of the present disclosure, a photomask can be manufactured through a simple process without requiring complicated processes.

[0028] Hereinafter, each component of the photomask blank according to the present disclosure will be described.

[0029] 1. Light-shielding film The light-shielding film in the present disclosure is disposed on one surface of a transparent substrate, is a member containing a chromium-based material, and has a sheet resistance within a predetermined range.

[0030] The sheet resistance of the light-shielding film is 10 3 Ω / □ or more, preferably 10 5 The sheet resistance of the light-shielding film is 10 7 The sheet resistance of the light-shielding film is 10 3 Ω / □ or more 10 7 Ω / □ or less, 10 5 Ω / □ or more 10 7It is preferable that the sheet resistance of the light-shielding film is Ω / □ or less. By having the sheet resistance of the light-shielding film within the above range, electrostatic breakdown can be suppressed. In addition, for example, as described later, when the light-shielding film has a low-reflection layer or region having a relatively high sheet resistance among the layers constituting the light-shielding film, the sheet resistance of the light-shielding film tends to increase as the thickness of the low-reflection layer or region having a relatively high sheet resistance increases, but if the thickness of the low-reflection layer or region is too thick, the etching rate becomes slow, and the plate-making properties of the light-shielding film may be reduced. Therefore, by having the sheet resistance of the light-shielding film be a predetermined value or less, good plate-making properties can be obtained.

[0031] Here, the sheet resistance is a value measured by a four-terminal four-probe method. For example, a low resistivity meter Loresta-GX MCP-T700 manufactured by Mitsubishi Chemical Corporation can be used as the resistivity meter, and for example, an ASP probe manufactured by Mitsubishi Chemical Corporation can be used as the four-probe probe. The sheet resistance is measured 10 times, and the average value is taken as the sheet resistance value.

[0032] As a means for controlling the sheet resistance of the light-shielding film within a predetermined range, for example, there is a method of making the light-shielding film contain an element that can be a factor of hindering the movement of free electrons. The element is preferably oxygen. That is, the light-shielding film preferably contains a chromium-based material containing oxygen.

[0033] The optical density of the light-shielding film against the exposure light is preferably 3.0 or more. Specifically, the optical density of the light-shielding film against light having a wavelength of 200 nm or more and 450 nm or less is preferably 3.0 or more. This is because, if the optical density of the light-shielding film is within the above range, the light-shielding film can have the desired light-shielding properties. The optical density can be measured using a spectrophotometer.

[0034] The thickness of the light-shielding film is not particularly limited as long as it has the above-mentioned sheet resistance and optical density, and can be, for example, 140 nm or more, preferably more than 150 nm, and particularly preferably 170 nm or more. The thickness of the light-shielding film can be, for example, 280 nm or less, preferably 270 nm or less, and particularly preferably 240 nm or less. The thickness of the light-shielding film can be, for example, 140 nm or more and 280 nm or less, preferably more than 150 nm and 270 nm or less, and particularly preferably 170 nm or more and 240 nm or less. If the thickness of the light-shielding film is within the above range, the light-shielding film can have the desired light-shielding properties. In addition, when the light-shielding film has a plurality of layers, the thickness is the thickness of the entire light-shielding film.

[0035] The light-shielding film may contain a chromium-based material and have a sheet resistance within the above range, and may have, for example, multiple layers or may be a film whose composition changes in the thickness direction. Hereinafter, the light-shielding film will be described separately for a case in which the light-shielding film has multiple layers (first embodiment) and a case in which the light-shielding film is a film whose composition changes in the thickness direction (second embodiment).

[0036] (1) First embodiment of the light-shielding film The light-shielding film of this embodiment contains a chromium-based material, has a sheet resistance within a predetermined range, and has a plurality of layers.

[0037] The light-shielding film may contain a chromium-based material, have a sheet resistance within a predetermined range, and have a plurality of layers. Among them, the light-shielding film preferably has a light-shielding layer and a low-reflection layer in order from the transparent substrate side. For example, in FIG. 1, the light-shielding film 3 has a light-shielding layer 3a and a low-reflection layer 3b in order from the transparent substrate 2 side. Since the low-reflection layer can prevent reflection of exposure light, a clearer pattern can be formed by using a photomask manufactured using the photomask blanks of the present disclosure. In addition, the low-reflection layer can have an anti-reflection function by containing, for example, a chromium-based material containing oxygen, nitrogen, or carbon, and the anti-reflection function can be enhanced when the low-reflection layer contains a chromium-based material containing oxygen. Here, when the low-reflection layer contains a chromium-based material containing oxygen, as described above, the sheet resistance of the entire light-shielding film can be increased to be within the above-mentioned predetermined range. Therefore, it is also possible to increase the sheet resistance of the entire light-shielding film to be within the predetermined range by the light-shielding film having a light-shielding layer and a low-reflection layer in order from the transparent substrate side.

[0038] In addition, the light-shielding film may further have a low-reflection layer between the transparent substrate and the light-shielding layer. That is, for example, as shown in FIG. 2, the light-shielding film 3 can have a second low-reflection layer 3c, a light-shielding layer 3a, and a first low-reflection layer 3b in order from the transparent substrate 2 side. Since the first low-reflection layer and the second low-reflection layer can prevent reflection of the exposure light, a clearer pattern can be formed by using a photomask manufactured using the photomask blanks of the present disclosure. In addition, the first low-reflection layer and the second low-reflection layer can have an anti-reflection function by, for example, containing a chromium-based material containing oxygen, nitrogen, or carbon, and the anti-reflection function can be enhanced when the chromium-based material containing oxygen is contained. Here, when the first low-reflection layer and the second low-reflection layer contain a chromium-based material containing oxygen, as described above, the sheet resistance of the entire light-shielding film can be increased to be within the above-mentioned predetermined range. Therefore, it is also possible to increase the sheet resistance of the entire light-shielding film to be within the predetermined range by the light-shielding film having the second low-reflection layer, the light-shielding layer, and the first low-reflection layer in order from the transparent substrate side.

[0039] In this specification, the low-reflection layer disposed on the surface of the light-shielding layer opposite the transparent substrate may be referred to as a first low-reflection layer, and the low-reflection layer disposed on the surface of the light-shielding layer facing the transparent substrate may be referred to as a second low-reflection layer.

[0040] The layers constituting the light-shielding film of this embodiment will be described below.

[0041] (a) Light shielding layer The light-shielding layer constituting the light-shielding film of this embodiment is a layer containing a chromium-based material, and can be the layer having the highest light-shielding properties among the layers constituting the light-shielding film.

[0042] The chromium-based material contained in the light-shielding layer can be a chromium-based material used in general photomask blanks, but is preferably a chromium compound. As described above, the sheet resistance of the entire light-shielding film can be increased by using a chromium-based material containing oxygen in the low-reflection layer, but if the electrical resistance of the light-shielding layer is extremely low compared to the electrical resistance of the low-reflection layer, there is a concern that a current will selectively flow through the light-shielding layer and electrostatic breakdown will occur. Therefore, it is preferable that the chromium-based material contained in the light-shielding layer is a chromium compound rather than metallic chromium. Examples of the chromium-based material include chromium-based materials containing at least one of oxygen, nitrogen, and carbon, such as chromium oxide, chromium oxide nitride, chromium oxide carbonitride, chromium oxide carbide, chromium nitride, and chromium carbide.

[0043] Among them, the chromium-based material contained in the light-shielding layer is preferably a chromium-based material containing oxygen. By making the light-shielding layer contain oxygen, the sheet resistance of the entire light-shielding film can be increased to fall within a predetermined range. Examples of the chromium-based material containing oxygen include chromium oxide, chromium oxide nitride, chromium oxide carbonitride, and chromium oxide carbide.

[0044] When the light-shielding layer contains a chromium-based material containing oxygen, the content of oxygen atoms in the light-shielding layer is not particularly limited as long as a light-shielding film having a desired sheet resistance and optical density can be obtained, but is preferably 5 atomic% or more, and more preferably 7 atomic% or more. The content of oxygen atoms in the light-shielding layer can be, for example, 20 atomic% or less. The content of oxygen atoms in the light-shielding layer is preferably 5 atomic% or more and 20 atomic% or less, and more preferably 7 atomic% or more and 20 atomic% or less. By having the content of oxygen atoms in the light-shielding layer within the above range, it is possible to achieve both high sheet resistance and high light-shielding properties in the entire light-shielding film.

[0045] Here, the content ratio of oxygen atoms in the light-shielding layer can be measured, for example, by X-ray photoelectron spectroscopy (XPS). As the X-ray photoelectron spectrometer, for example, Quantum2000 manufactured by ULVAC-PHI, Inc. can be used. Specific measurement conditions are shown below. ·Incoming X-ray: Monochromated Al Kα ray ·X-ray irradiation area (measurement area): 200μmφ ·X-ray output: 30W Photoelectron capture angle: 45° Charge neutralization conditions: Electron neutralization gun (0.02mA), low-acceleration Ar+ ion irradiation Measured peaks: Cr2p, Si2p, C1s, N1s, O1s Quantitative analysis: The background is determined by the Shirley method, and the atomic ratio is calculated from the obtained peak area using the relative response factor method.

[0046] The thickness of the light-shielding layer is not particularly limited as long as a light-shielding film having the above sheet resistance and optical density can be obtained, but is preferably, for example, 100 nm or more and 200 nm or less. By having the thickness of the light-shielding layer within the above range, the film strength of the light-shielding layer can be improved, electrostatic breakdown can be made less likely to occur, and resistance to heat generated by discharge current can be increased. In addition, if the thickness is too thin, sufficient light-shielding properties may not be obtained, and if the thickness is too thick, it may be difficult to accurately process the light-shielding pattern when manufacturing a photomask using the photomask blank of the present disclosure.

[0047] Examples of methods for forming the light-shielding layer include sputtering, vacuum deposition, and ion plating. More specifically, a method of mounting a Cr target in a vacuum chamber, introducing O2, N2, CO2 gas, and the like, and forming a film by reactive sputtering in a vacuum environment can be mentioned. In this method, the content ratio of oxygen atoms in the light-shielding layer can be adjusted by adjusting the ratio of O2 gas. This allows the sheet resistance and optical density of the entire light-shielding film to be adjusted.

[0048] (b) First low reflection layer The first low-reflection layer constituting the light-shielding film of this embodiment is disposed on the surface of the light-shielding layer opposite to the transparent substrate, and is a layer containing a chromium-based material.

[0049] The chromium-based material contained in the first low-reflection layer may be a chromium-based material used in general photomask blanks. Examples of the chromium-based material include chromium-based materials containing at least one of oxygen, nitrogen, and carbon, such as chromium oxide, chromium oxide nitride, chromium oxide carbonitride, chromium oxide carbide, chromium nitride, and chromium carbide.

[0050] Among them, the chromium-based material contained in the first low-reflection layer is preferably a chromium-based material containing oxygen. By making the first low-reflection layer contain oxygen, the sheet resistance of the entire light-shielding film can be increased to fall within a predetermined range. Examples of the chromium-based material containing oxygen include chromium oxide, chromium oxide nitride, chromium oxide carbonitride, and chromium oxide carbide.

[0051] When the first low-reflection layer and the light-shielding layer contain a chromium-based material containing oxygen, the content of oxygen atoms in the first low-reflection layer is preferably higher than the content of oxygen atoms in the light-shielding layer, because, as described above, the light-shielding layer preferably has the highest light-shielding ability among the layers constituting the light-shielding film.

[0052] The content ratio of oxygen atoms in the first low-reflection layer is greater than the content ratio of oxygen atoms in the light-shielding layer, and is not particularly limited as long as a light-shielding film having the desired sheet resistance and optical density can be obtained, and is appropriately adjusted depending on the target sheet resistance, optical density, anti-reflection function, chemical resistance, adhesion to resist, etc.

[0053] In addition, when the first low-reflection layer contains a chromium-based material containing at least carbon, the content of carbon atoms in the first low-reflection layer is not particularly limited as long as a light-shielding film having a desired sheet resistance and optical density can be obtained, but for example, it is preferably 5 atomic% or less, more preferably 3 atomic% or less, and even more preferably 2 atomic% or less. If the content of carbon atoms in the first low-reflection layer is too high, when the light-shielding film is patterned by wet etching, the etching rate may be slowed, and the plate-making properties of the first low-reflection layer may be reduced. Here, photomask blanks and photomasks are becoming larger with the increase in size of mother glass and display devices, and the thickness of the light-shielding film tends to be thicker in large photomask blanks and large photomasks. Therefore, in the case of large photomask blanks in particular, from the viewpoint of plate-making properties, it is preferable that the content of carbon atoms in the first low-reflection layer is relatively low so as to be within the above range. Note that the lower limit of the content of carbon atoms in the first low-reflection layer is not particularly limited.

[0054] In addition, when the first low reflection layer contains a chromium-based material containing at least nitrogen, the content of nitrogen atoms in the first low reflection layer is not particularly limited as long as a light-shielding film having a desired sheet resistance and optical density can be obtained, but for example, it is preferably 10 atomic % or less, more preferably 9.5 atomic % or less, and even more preferably 9.0 atomic % or less. By having the content of nitrogen atoms in the first low reflection layer in the above range, adhesion with the resist can be ensured. In addition, the lower limit of the content of nitrogen atoms in the first low reflection layer is not particularly limited.

[0055] In addition, when the first low-reflection layer contains a chromium-based material containing oxygen, nitrogen, and carbon, it is preferable that the content ratio of oxygen atoms, the content ratio of nitrogen atoms, and the content ratio of carbon atoms in the first low-reflection layer are each within the above-mentioned ranges.

[0056] Here, the method for measuring the oxygen atom content, carbon atom content, and nitrogen atom content in the first low-reflection layer can be the same as the method for measuring the oxygen atom content in the light-shielding layer.

[0057] The thickness of the first low-reflection layer is not particularly limited as long as it can exhibit an anti-reflection function and can obtain a light-shielding film having a desired sheet resistance and optical density, and can be, for example, 20 nm or more and 40 nm or less. If the thickness is too thin, the anti-reflection function may not be sufficiently obtained. If the thickness is too thick, it may be difficult to accurately process the light-shielding pattern when manufacturing a photomask using the photomask blank of the present disclosure. In addition, the first low-reflection layer is a layer that has a relatively high sheet resistance among the layers constituting the light-shielding film, and the sheet resistance of the light-shielding film tends to increase as the thickness of the first low-reflection layer increases, but if the thickness of the first low-reflection layer is too thick, the etching rate may be slowed down, and the plate-making properties of the first low-reflection layer may be reduced.

[0058] The low reflection layer can be formed by the same method as that for forming the light-shielding layer.

[0059] (c) Second low reflection layer The second low-reflection layer constituting the light-shielding film of this embodiment is disposed on the surface of the light-shielding layer facing the transparent substrate, and is a layer containing a chromium-based material.

[0060] The chromium-based material contained in the second low-reflection layer, the content ratio of oxygen atoms in the second low-reflection layer, the thickness of the second low-reflection layer, and the method of forming the second low-reflection layer can be the same as those of the first low-reflection layer.

[0061] (2) Second embodiment of the light-shielding film The light-shielding film of this embodiment is a film that contains a chromium-based material, has a sheet resistance within a predetermined range, and has a composition that changes in the thickness direction.

[0062] The fact that the light-shielding film is a film whose composition changes in the thickness direction can be confirmed, for example, by performing elemental analysis in the depth direction (thickness direction) by combining ion etching in the depth direction (thickness direction) with X-ray photoelectron spectroscopy (XPS). The X-ray photoelectron spectroscopy device and measurement conditions are as described above.

[0063] The chromium-based material contained in the light-shielding film may be a chromium-based material used in general photomask blanks. In particular, the chromium-based material contained in the light-shielding film is preferably a chromium-based material containing oxygen. This is because the sheet resistance of the light-shielding film can be increased to within a predetermined range by making the light-shielding film contain oxygen. Examples of chromium-based materials containing oxygen include chromium oxide, chromium oxide nitride, chromium oxide carbonitride, and chromium oxide carbide.

[0064] When the light-shielding film contains a chromium-based material containing oxygen, it is preferable that the light-shielding film has a concentration gradient in which the content ratio of oxygen atoms changes in the thickness direction. In this case, for example, the light-shielding film may have a concentration gradient in which the content ratio of oxygen atoms increases from the surface on the transparent substrate side toward the surface opposite the transparent substrate (hereinafter referred to as the first embodiment), or may have a concentration gradient in which the content ratio of oxygen atoms increases from the inside toward the surface on the transparent substrate side and also increases from the inside toward the surface opposite the transparent substrate (hereinafter referred to as the second embodiment).

[0065] In the first embodiment, the light-shielding film has a concentration gradient in which the content ratio of oxygen atoms increases from the surface on the transparent substrate side to the surface opposite the transparent substrate. That is, the light-shielding film can have a concentration gradient in which the content ratio of oxygen atoms is low on the surface on the transparent substrate side and high on the surface opposite the transparent substrate. In this case, an anti-reflection function can be imparted to the surface of the light-shielding film opposite the transparent substrate. In addition, by having the above-mentioned concentration gradient in the light-shielding film, the sheet resistance of the entire light-shielding film can be increased to within a predetermined range.

[0066] In the case of the first aspect, the content of oxygen atoms in the surface of the light-shielding film facing the transparent substrate may be less than the content of oxygen atoms in the surface of the light-shielding film facing the opposite side to the transparent substrate, and is not particularly limited as long as a light-shielding film having a desired sheet resistance and optical density can be obtained, but is preferably 5 atomic% or more, and more preferably 7 atomic% or more. The content of oxygen atoms in the surface of the light-shielding film facing the transparent substrate may be, for example, 20 atomic% or less. The content of oxygen atoms in the surface of the light-shielding film facing the transparent substrate is, for example, preferably 5 atomic% or more and 20 atomic% or less, and more preferably 7 atomic% or more and 20 atomic% or less. By having the content of oxygen atoms in the surface of the light-shielding film facing the transparent substrate within the above range, the light-shielding film as a whole can achieve both high sheet resistance and high light-shielding properties.

[0067] In the first embodiment, the thickness of the region in which the oxygen atom content is 5 atomic % or more on the transparent substrate side of the light-shielding film is, for example, 100 nm or more and 200 nm or less. That is, the light-shielding film preferably has a region in which the oxygen atom content is within a predetermined range, with a predetermined thickness, in the thickness direction from the transparent substrate side. By having the thickness of the region within the above range, the film strength of the light-shielding film can be improved, electrostatic breakdown can be made less likely to occur, and resistance to heat generated by discharge current can be increased. In addition, if the thickness of the region is too thin, sufficient light-shielding properties may not be obtained, and if the thickness of the region is too thick, it may be difficult to accurately process the light-shielding pattern when manufacturing a photomask using the photomask blank of the present disclosure.

[0068] In addition, in the case of the first embodiment described above, the oxygen atom content in the surface of the light-shielding film opposite the transparent substrate need only be greater than the oxygen atom content in the surface of the light-shielding film facing the transparent substrate, and is not particularly limited as long as a light-shielding film having the desired sheet resistance and optical density can be obtained, and is appropriately adjusted depending on the target sheet resistance, optical density, etc.

[0069] In the second embodiment, the light-shielding film has a concentration gradient in which the content ratio of oxygen atoms increases from the inside toward the surface on the transparent substrate side, and the content ratio of oxygen atoms increases from the inside toward the surface opposite the transparent substrate. That is, the light-shielding film can have a concentration gradient in which the content ratio of oxygen atoms is low in the inside, and the content ratio of oxygen atoms is high on the surface on the transparent substrate side and on the surface opposite the transparent substrate. In this case, an anti-reflection function can be imparted to the surface of the light-shielding film on the transparent substrate side and the surface of the light-shielding film opposite the transparent substrate. In addition, by having the above-mentioned concentration gradient in the light-shielding film, the sheet resistance of the entire light-shielding film can be increased to within a predetermined range.

[0070] In the case of the second aspect, the content of oxygen atoms in the inside of the light-shielding film may be less than the content of oxygen atoms in the surface of the light-shielding film facing the transparent substrate and the content of oxygen atoms in the surface of the light-shielding film opposite to the transparent substrate, and is not particularly limited as long as a light-shielding film having a desired sheet resistance and optical density can be obtained, but for example, it is preferably 5 atomic% or more, and more preferably 7 atomic% or more. The content of oxygen atoms in the inside of the light-shielding film can be, for example, 20 atomic% or less. The content of oxygen atoms in the inside of the light-shielding film is, for example, preferably 5 atomic% or more and 20 atomic% or less, and more preferably 7 atomic% or more and 20 atomic% or less. By having the content of oxygen atoms in the inside of the light-shielding film within the above range, it is possible to achieve both high sheet resistance and high light-shielding properties in the entire light-shielding film.

[0071] In the second aspect, the thickness of the region in the light-shielding film in which the content ratio of oxygen atoms is 5 atomic % or more is preferably, for example, 100 nm or more and 200 nm or less. That is, the light-shielding film preferably has a region in the light-shielding film with a predetermined thickness in which the content ratio of oxygen atoms is within a predetermined range. By having the thickness of the region within the above range, the film strength of the light-shielding film can be improved, electrostatic breakdown can be made less likely to occur, and resistance to heat generated by discharge current can be increased. In addition, if the thickness of the region is too thin, sufficient light-shielding properties may not be obtained, and if the thickness of the region is too thick, it may be difficult to accurately process the light-shielding pattern when manufacturing a photomask using the photomask blank of the present disclosure.

[0072] In addition, in the case of the above-mentioned second embodiment, the content ratio of oxygen atoms on the surface of the light-shielding film facing the transparent substrate and the content ratio of oxygen atoms on the surface of the light-shielding film opposite the transparent substrate need only be greater than the content ratio of oxygen atoms inside the light-shielding film, and are not particularly limited as long as a light-shielding film having the desired sheet resistance and optical density can be obtained, and are appropriately adjusted depending on the target sheet resistance, optical density, etc.

[0073] The oxygen atom content in the thickness direction of the light-shielding film can be measured by, for example, performing elemental analysis in the depth direction (thickness direction) by combining X-ray photoelectron spectroscopy (XPS) with ion etching in the depth direction (thickness direction). The X-ray photoelectron spectroscopy device and measurement conditions are as described above.

[0074] The method for forming the light-shielding film is not particularly limited as long as it can change the composition in the thickness direction, and examples thereof include a sputtering method. More specifically, a method in which a Cr target is placed in a vacuum chamber, O2, N2, CO2 gas, etc. are introduced, and a film is formed by reactive sputtering in a vacuum environment can be mentioned. In this method, the content ratio of oxygen atoms in the light-shielding film can be adjusted by adjusting the ratio of O2 gas. This allows the sheet resistance and optical density of the entire light-shielding film to be adjusted.

[0075] 2. Transparent substrate The transparent substrate in the present disclosure is a member that supports the light-shielding film and has optical transparency.

[0076] The transparent substrate can be a transparent substrate used in a general photomask. The transparent substrate can be, for example, an optically polished transparent substrate, specifically, soda-lime glass, aluminoborosilicate glass, borosilicate glass, synthetic quartz, fluorite, calcium fluoride, etc. Among them, synthetic quartz is preferably used, because it has a small thermal expansion coefficient and is easy to manufacture a photomask. In addition, a resin substrate can be used as the transparent substrate.

[0077] The light transmittance of the transparent substrate is not particularly limited as long as it is comparable to that of a transparent substrate used in a general photomask.

[0078] The thickness of the transparent substrate can be appropriately selected depending on the application of the photomask blank of the present disclosure.

[0079] 3.Applications The photomask blanks of the present disclosure are suitable for use in the manufacture of binary masks.

[0080] The photomask blank in the present disclosure is preferably a large photomask blank used for manufacturing a large photomask. The size of the large photomask blank can be, for example, a size in which the length of at least one side is 350 mm or more.

[0081] B. Photomask The photomask in the present disclosure has a transparent substrate and a light-shielding pattern that is disposed on one surface of the transparent substrate and contains a chromium-based material, and the sheet resistance of the light-shielding pattern is within a predetermined range.

[0082] Fig. 3 is a schematic cross-sectional view illustrating a photomask of the present disclosure. As shown in Fig. 3, the photomask 10 has a transparent substrate 12 and a light-shielding pattern 13 that is disposed on one surface of the transparent substrate 12 and contains a chromium-based material. The sheet resistance of the light-shielding pattern 13 is within a predetermined range. In the example shown in Fig. 3, the light-shielding pattern 13 has a light-shielding layer 13a and a low-reflection layer 13b in this order from the transparent substrate 2 side, but is not limited to this.

[0083] According to the present disclosure, since the sheet resistance of the light-shielding pattern is high within the above range, when static electricity charged in the photomask is discharged, the current flowing through the light-shielding pattern can be reduced. This makes it possible to reduce heat generated by the discharge current. As a result, it is possible to suppress electrostatic damage.

[0084] Furthermore, according to the present disclosure, the sheet resistance of the light-shielding pattern can be adjusted by adjusting the composition of the light-shielding pattern, for example, including a chromium-based material, thereby making it possible to manufacture a photomask through a simple process without requiring complicated processes.

[0085] Each component of the photomask according to the present disclosure will be described below.

[0086] 1. Shading pattern The light-shielding pattern in the present disclosure is disposed on one surface of a transparent substrate, is a member containing a chromium-based material, and has a sheet resistance within a predetermined range.

[0087] The sheet resistance, optical density, thickness, etc. of the light-shielding pattern can be similar to those of the light-shielding film in the above-mentioned photomask blanks, so the description thereof will be omitted here.

[0088] The width of the light-shielding pattern is not particularly limited, but can be, for example, 0.1 μm or more and 10 μm or less.

[0089] The shape of the light-shielding patterns and the distance between adjacent light-shielding patterns are appropriately adjusted depending on the application of the photomask of the present disclosure.

[0090] The light-shielding pattern may contain a chromium-based material and have a sheet resistance within the above range, and may have, for example, multiple layers or may be a film whose composition changes in the thickness direction. Hereinafter, the light-shielding pattern will be described separately for a case in which the light-shielding pattern has multiple layers (first embodiment) and a case in which the light-shielding pattern is a film whose composition changes in the thickness direction (second embodiment).

[0091] (1) First embodiment of the light-shielding pattern The light-shielding pattern of this embodiment contains a chromium-based material, has a sheet resistance within a predetermined range, and has a plurality of layers.

[0092] The light-shielding pattern may contain a chromium-based material, have a sheet resistance within a predetermined range, and have multiple layers, but it is preferable that the light-shielding pattern has a light-shielding layer and a low-reflection layer in this order from the transparent substrate side. For example, in FIG. 3, the light-shielding pattern 13 has a light-shielding layer 13a and a low-reflection layer 13b in this order from the transparent substrate 12 side. The reason why this is preferable is the same as that of the light-shielding film of the first embodiment in the photomask blanks described above, so the explanation here is omitted.

[0093] The light-shielding pattern may further have a low-reflection layer between the transparent substrate and the light-shielding layer. That is, for example, as shown in Fig. 4, the light-shielding pattern 13 may have, in order from the transparent substrate 12 side, a second low-reflection layer 13c, a light-shielding layer 13a, and a first low-reflection layer 13b.

[0094] In this specification, the low-reflection layer disposed on the surface of the light-shielding pattern opposite the transparent substrate may be referred to as a first low-reflection layer, and the low-reflection layer disposed on the surface of the light-shielding pattern facing the transparent substrate may be referred to as a second low-reflection layer.

[0095] Each layer constituting the light-shielding pattern of the first embodiment can be similar to the light-shielding film of the first embodiment in the above-mentioned photomask blank, and therefore a description thereof will be omitted here.

[0096] (2) Second embodiment of the light-shielding pattern The light-shielding pattern of this embodiment is a film that contains a chromium-based material, has a sheet resistance within a predetermined range, and has a composition that changes in the thickness direction.

[0097] The configuration of the light-shielding pattern of the second embodiment can be the same as that of the light-shielding film of the second embodiment in the above-mentioned photomask blank, so a description thereof will be omitted here.

[0098] 2. Transparent substrate The transparent substrate in the present disclosure is a member that supports the light-shielding pattern and has optical transparency. The transparent substrate may be the same as the transparent substrate in the above-mentioned photomask blank.

[0099] 3. Photomask manufacturing method The method for manufacturing a photomask in the present disclosure is not particularly limited as long as it is a method capable of manufacturing a photomask having the above-described configuration, and can be the same as a general method for manufacturing a photomask.

[0100] For example, first, a mask blank having a light-shielding film on one side of a transparent substrate is prepared. Next, a resist pattern having a desired shape is formed on the light-shielding film, and the light-shielding film is etched using the resist pattern as a mask to form a light-shielding pattern from the light-shielding film. In this way, a photomask is produced.

[0101] 4. Photomask The photomask in the present disclosure is preferably a large photomask. The size of the large photomask can be the same as the size of the large photomask blank described above.

[0102] The present disclosure is not limited to the above-described embodiments. The above-described embodiments are merely examples, and anything that has substantially the same configuration as the technical idea described in the claims of the present disclosure and exhibits similar effects is included in the technical scope of the present disclosure. EXAMPLES

[0103] The present disclosure will be described in further detail below with reference to examples and comparative examples.

[0104] [Example 1] First, a mask blank was prepared comprising a 6-inch square precision-polished synthetic quartz glass and a light-shielding film disposed on the surface of the synthetic quartz glass and having a layered structure in which a second low-reflection layer with a thickness of 30 nm, a light-shielding layer with a thickness of 150 nm, and a first low-reflection layer with a thickness of 30 nm were layered in this order.

[0105] In the preparation of the mask blanks, the light-shielding film was formed by depositing the second low-reflection layer, the light-shielding layer, and the first low-reflection layer on the surface of synthetic quartz glass in that order using a sputtering method. In this case, the deposition of the second low-reflection layer, the light-shielding layer, and the first low-reflection layer was performed separately using a sputtering device with gas replacement. In addition, the second low-reflection layer, the light-shielding layer, and the first low-reflection layer were deposited by reactive sputtering in a vacuum environment with a Cr target installed in a vacuum chamber and O2, N2, and CO2 gases introduced. The deposition conditions for the light-shielding layer were set to a condition in which the ratio of O2 gas was increased compared to the deposition conditions for the light-shielding film of a general binary mask. In addition, the deposition conditions for the first low-reflection layer and the second low-reflection layer were set to the same conditions as the deposition conditions for the low-reflection film in the light-shielding pattern of a general binary mask.

[0106] Next, a resist pattern was formed on the light-shielding film, and the light-shielding film was etched using the resist pattern as an etching mask to form a light-shielding pattern having the pattern shape shown in Figures 5(a) to (b), thereby producing a photomask.

[0107] 5(a) and (b) are schematic plan views of the photomask, with FIG. 5(a) being an overall view of a 6-inch square photomask, and FIG. 5(b) being an enlarged view of part A in FIG. 5(a). In FIG. 5(b), the light-shielding pattern 13' is a line pattern with 40 lines and a line width of 10 μm. The photomasks were fabricated by varying the distance d between adjacent light-shielding patterns 13' between 2 μm and 15 μm.

[0108] [Example 2] First, a mask blank was prepared, which included a 6-inch square precision-polished synthetic quartz glass and a light-shielding layer disposed on the surface of the synthetic quartz glass and having a layered structure in which a second low-reflection layer with a thickness of 30 nm, a light-shielding layer with a thickness of 120 nm, and a first low-reflection layer with a thickness of 30 nm were layered in this order. The method for preparing the mask blank was the same as in Example 1.

[0109] Next, a photomask was produced in the same manner as in Example 1.

[0110] [Comparative Example 1] First, a mask blank was prepared comprising a 6-inch square precision-polished synthetic quartz glass and a light-shielding film having a layered structure in which a light-shielding layer with a thickness of 85 nm and a low-reflection layer with a thickness of 30 nm were laminated on the surface of the synthetic quartz glass in that order.

[0111] In the preparation of the mask blanks, the light-shielding film was formed by depositing a light-shielding layer and a low-reflection layer on the surface of synthetic quartz glass using a sputtering method. In this case, the light-shielding layer and the low-reflection layer were deposited separately using a sputtering device with gases replaced. The low-reflection layer was deposited by reactive sputtering in a vacuum environment with a Cr target installed in a vacuum chamber and O2, N2, and CO2 gases introduced. The deposition conditions for the low-reflection layer were the same as those for the low-reflection film in the light-shielding pattern of a general binary mask. Furthermore, the deposition conditions for the light-shielding layer were the same as those for the chromium film in the light-shielding pattern of a general binary mask.

[0112] Next, a photomask was produced in the same manner as in Example 1.

[0113] [Example 3] Except for changing the size, photomask blanks and photomasks were produced in the same manner as in Example 1. The size was 800 mm x 920 mm.

[0114] [Comparative Example 2] A photomask was produced in the same manner as in Comparative Example 1, except that the size was changed to 1220 mm x 1400 mm.

[0115] [Example 4] First, a mask blank was prepared, which included a 6-inch square precision-polished synthetic quartz glass and a light-shielding film disposed on the surface of the synthetic quartz glass and having a layered structure in which a second low-reflection layer with a thickness of 30 nm, a light-shielding layer with a thickness of 140 nm, and a first low-reflection layer with a thickness of 30 nm were layered in this order. The method for preparing the mask blank was the same as in Example 1.

[0116] Next, a photomask was produced in the same manner as in Example 1.

[0117] [Comparative Example 3] First, a mask blank was prepared, which included a 6-inch square precision-polished synthetic quartz glass and a light-shielding film disposed on the surface of the synthetic quartz glass and having a layered structure in which a second low-reflection layer with a thickness of 30 nm, a light-shielding layer with a thickness of 140 nm, and a first low-reflection layer with a thickness of 30 nm were layered in this order. The method for preparing the mask blank was the same as in Example 1.

[0118] Next, a photomask was produced in the same manner as in Example 1.

[0119] [Comparative Example 4] First, a mask blank was prepared, which included a 6-inch square precision-polished synthetic quartz glass and a light-shielding film disposed on the surface of the synthetic quartz glass and having a layered structure in which a second low-reflection layer with a thickness of 30 nm, a light-shielding layer with a thickness of 150 nm, and a first low-reflection layer with a thickness of 39 nm were layered in this order. The method for preparing the mask blank was the same as in Example 1.

[0120] Next, a photomask was produced in the same manner as in Example 1.

[0121] (evaluation) (1) Sheet resistance The sheet resistance of the light-shielding film was measured for the 6-inch square photomask blanks of Examples 1 to 2 and 4 and Comparative Examples 1, 3 and 4. The sheet resistance was measured using a low resistivity meter Loresta-GX MCP-T700 manufactured by Mitsubishi Chemical Corporation, and a four-terminal four-probe method using an ASP probe manufactured by Mitsubishi Chemical Corporation. The sheet resistance was measured 10 times and the average value was calculated. The results are shown in Table 1.

[0122] [Table 1]

[0123] (2) Composition analysis For the 6-inch square photomask blanks of Examples 1 to 2 and 4 and Comparative Examples 1 and 3, composition analysis of the light-shielding film was performed by XPS analysis. Specifically, an ULVAC-PHI Quantum2000 X-ray photoelectron spectrometer was used to ion-etch the light-shielding film and analyze the composition of the surface of the light-shielding layer exposed. The measurement conditions were as follows. The results are shown in Table 2. ·Incoming X-ray: Monochromated Al Kα ray ·X-ray irradiation area (measurement area): 200μmφ ·X-ray output: 30W Photoelectron capture angle: 45° Charge neutralization conditions: Electron neutralization gun (0.02mA), low acceleration Ar + Ion bombardment Measured peaks: Cr2p, Si2p, C1s, N1s, O1s Quantitative analysis: The background was determined by the Shirley method, and the atomic ratio was calculated from the peak areas obtained using the relative response factor method.

[0124] [Table 2]

[0125] The light-shielding layer of Example 1 had Cr: 88.6 atomic %, C: 2.4 atomic %, and O: 7.6 atomic %. The light-shielding layer of Example 2 had Cr: 91.1 atomic %, C: 1.9 atomic %, and O: 5.8 atomic %. The light-shielding layer of Comparative Example 1 had Cr: 92.4 atomic %, C: 1.2 atomic %, and O: 4.4 atomic %.

[0126] (3) Static electricity resistance The electrostatic resistance of the 6-inch square photomasks of Examples 1 to 2 and 4 and Comparative Examples 1 and 3 was evaluated using an electrostatic tester ESS-6008 manufactured by Noise Laboratory Co., Ltd. The measurement conditions were a voltage of 500V, a capacitance of 100pF±10%, and a resistance of 1.5kΩ±1%. Specifically, after charging 500V to the X and Y parts in FIG. 5(b) using the electrostatic tester, the space between adjacent light-shielding patterns 13' was observed under a microscope to confirm the occurrence of electrostatic breakdown. Those that did not cause electrostatic breakdown were evaluated as "good", and those that did cause electrostatic breakdown were evaluated as "poor". The results are shown in Table 3. Note that the smaller the distance d between adjacent light-shielding patterns, the more likely it is that electrostatic breakdown will occur.

[0127] [Table 3]

[0128] The photomasks of Example 3 and Comparative Example 2 were also evaluated for static electricity resistance in the same manner as above. The results are shown in Table 4.

[0129] [Table 4]

[0130] As can be seen from Tables 3 and 4, the photomasks of Examples 1 to 4 were excellent in static electricity resistance.

[0131] (4) Plate-making properties In Comparative Example 4, the first low-reflection layer was thicker than in Example 1, so the time it took to etch the first low-reflection layer was longer than the time it took to etch the light-shielding layer and the second low-reflection layer, and the difference in cross-sectional shape was likely to occur between the upper and lower layers of the light-shielding film. A vertical cross-sectional shape is required for a photomask, but in Comparative Example 4, it was difficult to maintain the cross-sectional shape, especially for fine lines, and plate-making properties were poor. [Explanation of symbols]

[0132] 1. Photomask blanks 2, 12 ... Transparent substrate 3. Light-shielding film 3a, 13a … Light shielding layer 3b, 13b...Low reflection layer (first low reflection layer) 3c, 13c…Second low reflection layer 10 … Photomask 13 … Shading pattern

Claims

1. A photomask blank having a transparent substrate and a light-shielding film that is disposed on one surface of the transparent substrate and contains a chromium-based material, The sheet resistance of the light-shielding film is 10 5 Ω / □ or more. ７ Ω / □ or less, the light-shielding film has a light-shielding layer and a first low-reflection layer in this order from the transparent substrate side, The photomask blank, wherein the first low-reflection layer and the light-shielding layer are made of a chromium-based material containing oxygen.

2. The photomask blank according to claim 1 , wherein the light-shielding layer has a thickness of 100 nm or more and 200 nm or less.

3. The light-shielding film is, in order from the transparent substrate side, a second low-reflection layer, the light-shielding layer, and the first low-reflection layer; 3. The photomask blank according to claim 1, wherein the second low reflective layer is made of a chromium-based material containing oxygen.

4. A photomask blank as described in claim 3, wherein the content of oxygen atoms in the first low-reflection layer and the second low-reflection layer is greater than the content of oxygen atoms in the light-shielding layer.

5. A photomask blank described in any one of claims 1 to 4, wherein the content of oxygen atoms in the light-shielding layer is 7 atomic% or more and 20 atomic% or less.

6. The photomask blank according to claim 1 , wherein the light-shielding film has a thickness of 140 nm or more and 280 nm or less.

7. A photomask blank described in any one of claims 1 to 6, which is a large photomask blank with a side length of 350 mm or more.

8. A photomask having a transparent substrate and a light-shielding pattern including a chromium-based material and disposed on one surface of the transparent substrate, The sheet resistance of the light-shielding pattern is 10 5 Ω / □ or more. ７ Ω / □ or less, the light-shielding pattern has a light-shielding layer and a first low-reflection layer in this order from the transparent substrate side, The photomask, wherein the first low reflection layer and the light-shielding layer are made of a chromium-based material containing oxygen.

9. The photomask according to claim 8 , wherein the light-shielding layer has a thickness of 100 nm or more and 200 nm or less.

10. The light-shielding pattern is, in order from the transparent substrate side, a second low-reflection layer, the light-shielding layer, and the first low-reflection layer; 10. The photomask according to claim 8, wherein the second low reflection layer is made of a chromium-based material containing oxygen.

11. A photomask as described in claim 10, wherein the content of oxygen atoms in the first low-reflection layer and the second low-reflection layer is greater than the content of oxygen atoms in the light-shielding layer.

12. A photomask described in any one of claims 8 to 11, wherein the content of oxygen atoms in the light-shielding layer is 7 atomic % or more and 20 atomic % or less.

13. 12. The photomask according to claim 8, wherein the light-shielding pattern has a thickness of 140 nm or more and 280 nm or less.

14. A photomask described in any one of claims 8 to 13, which is a large photomask with a side length of 350 mm or more.

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