TWI733033B - Photomask blank and method of manufacturing photomask blank, method of manufacturing photomask, and method of manufacturing display device - Google Patents

Abstract

The present invention provides a photomask substrate that can obtain a high-precision mask pattern when fabricating a photomask by etching, and meets the optical characteristics that can suppress display unevenness when the photomask is used to fabricate a display device. The photomask substrate of the present invention is characterized in that it is a photomask substrate used when manufacturing a photomask for display device manufacturing, and has: a transparent substrate, which is composed of a material that is substantially transparent to exposure light; and a light-shielding film , Which is provided on a transparent substrate and is composed of a material that is substantially opaque to exposure light; the light-shielding film is equipped with a first reflection suppression layer, a light-shielding layer, and a second reflection suppression layer from the transparent substrate side, and the first reflection suppression The layer is a chromium-based material containing chromium, oxygen and nitrogen, and has a composition with a chromium content of 25 to 75 atomic %, an oxygen content of 15 to 45 atomic %, and a nitrogen content of 10 to 30 atomic %. The light-shielding layer contains a chromium-based material containing chromium and nitrogen, and has a composition with a chromium content of 70 to 95 atomic% and a nitrogen content of 5 to 30 atomic %. The second reflection suppression layer contains chromium, oxygen and nitrogen. The chromium-based material has a composition with a chromium content of 30 to 75 atomic%, an oxygen content of 20 to 50 atomic%, and a nitrogen content of 5 to 20 atomic% to make the front and back of the light-shielding film The thickness of the first reflection suppression layer, the light shielding layer, and the second reflection suppression layer are set so that the reflectance with respect to the exposure wavelength of the exposure light is 10% or less, and the optical density is 3.0 or more.

Description

Photomask substrate and its manufacturing method, photomask manufacturing method, and display device manufacturing method

The present invention relates to a photomask substrate and a manufacturing method thereof, a manufacturing method of a photomask, and a manufacturing method of a display device.

In display devices such as FPD (Flat Panel Display) represented by LCD (Liquid Crystal Display), as large screens and wide viewing angles, high-definition and high-speed displays are rapidly developing. One of the elements required for this high-definition and high-speed display is the production of electronic circuit patterns such as components or wirings with fine and high dimensional accuracy. The patterning of the electronic circuit for the display device mostly uses photolithography. Therefore, there is a need for a mask for manufacturing a display device formed with a fine and high-precision pattern.

The photomask used in the manufacture of the display device is made of the photomask substrate. The mask base is formed by setting a light-shielding film made of a material that is opaque to exposure light on a transparent substrate made of synthetic quartz glass or the like. In the photomask base or the photomask, in order to suppress the reflection of light during exposure, reflection suppression layers are provided on the front and back sides of the light shielding film. For example, the photomask base is made of, for example, the first reflection suppression layer, The light-shielding layer and the second reflection suppression layer are laminated. The photomask is made by patterning the light-shielding film of the photomask base by wet etching or the like and forming a specific mask pattern.

The technology associated with the photomask used for manufacturing such a display device, the photomask substrate that becomes the original version, and the manufacturing methods of both are disclosed in Patent Document 1. [Prior Technical Documents] [Patent Documents]

[Patent Document 1] Korean Registered Patent No. 10-1473163

[The problem to be solved by the invention]

In the manufacture of display devices (such as display panels for TV (TeleVision, television)), for example, a photomask is used to transfer a specific pattern to the substrate for the display device, and then the substrate for the display device is slid to transfer the specific pattern. Thus, pattern transfer is repeated. In this transfer, the reflected light from the back side of the photomask when the exposure light from the light source of the exposure device is incident on the photomask, or the reflected light from the transferred body after the exposure light passes through the photomask, returns to the front side of the photomask The influence of the reflected light on the side is sometimes in the vicinity of the overlap of the display device, and the exposure light above the assumption is irradiated. As a result, it is sometimes exposed in such a way that adjacent patterns partially overlap each other, which may cause display unevenness in the manufactured display device.

Therefore, in the mask substrate, in order to suppress display unevenness, it is required that the reflectance of the front and back surfaces of the light-shielding film is 10% or less (for example, the wavelength of 365 nm to 436 nm), and more preferably 5% or less (for example, 400 nm～436 nm). Furthermore, from the viewpoint of improving the CD uniformity of the mask, if the front reflection of the light-shielding film in the laser drawing light is considered, it is required that the reflectivity of the front side of the light-shielding film is 5% or less (for example, a wavelength of 413 nm). More preferably, it is 3% or less (for example, a wavelength of 413 nm).

In addition, in addition to the requirements for high-definition and high-speed display of display devices, photomasks used in the manufacture of display devices have tended to be larger in size. In recent years, rectangular substrates with shorter sides of 850 mm or more will be used. The super-large mask is used in the manufacture of display devices. In addition, as the above-mentioned large-scale photomask with a short side length of 850 mm or more, there are 850 mm×1200 mm size for G7, 1220 mm×1400 mm size for G8, and 1620 mm×1780 mm size for G10, especially The CD Uniformity, which is the mask pattern in this large mask, requires a high-precision mask pattern below 100 nm.

In the previously proposed photomask base of Patent Document 1, when the length of the short side of the substrate is 850 mm or more, the reflectivity of the front and back of the light-shielding film cannot be set to 10% or less with respect to the exposure wavelength, and The CD uniformity of the mask pattern in the mask made by using the mask substrate is below 100 nm.

The object of the present invention is to provide a mask substrate that obtains a high-precision mask pattern when the mask is manufactured by etching, and satisfies the optical characteristics of suppressing uneven display when the mask is used to manufacture a display device. [Technical means to solve the problem]

(Constitution 1) A photomask base, characterized in that it is a photomask base used when manufacturing a display device manufacturing photomask, and has: a transparent substrate, which is composed of a material that is substantially transparent to exposure light ; A light-shielding film, which is provided on the transparent substrate and is composed of a material that is substantially opaque to the exposure light; The light-shielding film includes a first reflection suppression layer, a light-shielding layer, and a second reflection from the transparent substrate side The suppression layer, the first reflection suppression layer is a chromium-based material containing chromium, oxygen and nitrogen, and has a chromium content of 25 to 75 atomic %, an oxygen content of 15 to 45 atomic %, and a nitrogen content of The light-shielding layer is composed of a chromium-based material containing chromium and nitrogen, and has a composition with a chromium content of 70 to 95 atomic% and a nitrogen content of 5-30 atomic%. The second The reflection suppression layer is a chromium-based material containing chromium, oxygen and nitrogen, and has a chromium content of 30 to 75 atomic %, an oxygen content of 20 to 50 atomic %, and a nitrogen content of 5 to 20 atomic% The composition is such that the reflectance of the front and back surfaces of the light-shielding film with respect to the exposure wavelength of the exposure light is 10% or less, and the optical density is 3.0 or more, and the first reflection suppression layer, the light-shielding layer, And the film thickness of the above-mentioned second reflection suppression layer.

(Constitution 2) The mask substrate of the configuration 1 is characterized in that the content of chromium of the first reflection suppression layer is 50 to 75 atomic %, the content of oxygen is 15 to 35 atomic %, and the content of nitrogen is The content of chromium in the second reflection suppression layer is 50 to 75 atomic%, the content of oxygen is 20 to 40 atomic%, and the content of nitrogen is 5 to 20 atomic%.

(Configuration 3) The mask substrate of configuration 1 or 2, characterized in that the first reflection suppressing layer and the second reflection suppressing layer each have at least one element of oxygen and nitrogen. The content of at least one element is along the thickness direction of the film. An area where the composition changes continuously or in stages.

(Configuration 4) The mask base of any one of the configurations 1 to 3 is characterized in that the second reflection suppression layer has a region where the oxygen content increases toward the light shielding layer side in the film thickness direction.

(Configuration 5) The mask base of any one of the configurations 1 to 4 is characterized in that the second reflection suppression layer has a region where the nitrogen content decreases toward the light shielding layer side in the film thickness direction.

(Configuration 6) The mask base of any one of configurations 1 to 5 is characterized in that the first reflection suppression layer has the transparent substrate facing the film thickness direction, and the oxygen content is increased and the nitrogen content is reduced. area.

(Configuration 7) The mask base of any one of the configurations 1 to 6, characterized in that the second reflection suppression layer is configured such that the oxygen content rate is higher than that of the first reflection suppression layer.

(Configuration 8) The mask base of any one of the configurations 1 to 7, characterized in that the first reflection suppression layer is configured such that the nitrogen content is higher than that of the second reflection suppression layer.

(Configuration 9) The mask substrate of any one of the configurations 1 to 8, characterized in that the light shielding layer contains chromium (Cr) and chromium nitride (Cr ₂ N).

(Configuration 10) As the mask base of any one of the configurations 1 to 9, wherein the first reflection suppression layer and the second reflection suppression layer include chromium nitride (CrN), chromium oxide (III) (Cr ₂ O ₃ ) And chromium oxide (VI) (CrO ₃ ).

(Configuration 11) The mask base of any one of components 1 to 10 is characterized in that the transparent substrate is a rectangular substrate, and the length of the short side of the substrate is 850 mm or more and 1620 mm or less.

(Configuration 12) The mask base of any one of configurations 1 to 11 is characterized in that between the transparent substrate and the light-shielding film, there is a translucent layer having an optical density lower than that of the light-shielding film. Light film.

(Configuration 13) The mask base of any one of Configurations 1 to 11 is characterized by further including a phase shift film between the transparent substrate and the light shielding film.

(Constitution 14) A method for manufacturing a photomask substrate, characterized in that it is a method for manufacturing a photomask substrate used when manufacturing a photomask for manufacturing a display device, and the photomask is substantially transparent to exposure light. A light-shielding film made of a material that is substantially opaque with respect to exposure light is formed by sputtering on a transparent substrate made of the material, and has the following steps: On the above-mentioned transparent substrate, by using sputtering containing chromium Reactive sputtering of a plating target, a reactive gas containing oxygen-based gas, nitrogen-based gas, and a sputtering gas containing rare gas to form a first reflection suppression layer, which contains chromium, oxygen and Nitrogen chromium-based material with a chromium content of 25 to 75 atomic %, an oxygen content of 15 to 45 atomic %, and a nitrogen content of 10 to 30 atomic %; on the above-mentioned first reflection suppression layer , By using a sputtering target containing chromium, reactive gas containing a nitrogen-based gas and a sputtering gas containing a rare gas to form a light-shielding layer, the light-shielding layer is a chromium-based material containing chromium and nitrogen And it has a composition with a chromium content of 70 to 95 atomic% and a nitrogen content of 5 to 30 atomic%; and on the light-shielding layer, by using a sputtering target containing chromium, and containing oxygen-containing gas, The reactive sputtering of the reactive gas of nitrogen gas and the sputtering gas of rare gas forms a second reflection suppression layer, which is a chromium-based material containing chromium, oxygen and nitrogen and has a chromium content rate The composition is 30 to 75 atomic %, the oxygen content is 20 to 50 atomic %, and the nitrogen content is 5 to 20 atomic %; in the above reactive sputtering, the flow rate of the reactive gas contained in the sputtering gas The flow rate of the metal mode is selected, and the first reflection suppression layer is formed so that the reflectance of the front and back of the light-shielding film with respect to the exposure wavelength of the exposure light is 10% or less, and the optical density is 3.0 or more The film thickness of the light-shielding layer and the second reflection suppression layer.

(Composition 15) The method for manufacturing the mask substrate of the composition 14 is characterized in that the oxygen-based gas is oxygen (O ₂ ) gas.

(Configuration 16) The manufacturing method of the mask base of the configuration 14 or 15, characterized in that the first reflection suppression layer, the light shielding layer, and the second reflection suppression layer use one side so that the transparent substrate is opposed to the sputtering The target is formed by an in-line sputtering device in which the light-shielding film is formed on one side while moving relatively.

(Configuration 17) The manufacturing method of the mask base of any one of the configurations 14 to 16, characterized in that: between the transparent substrate and the light-shielding film, a layer having an optical density lower than that of the light-shielding film is formed Semi-transparent film.

(Configuration 18) The manufacturing method of the mask base of any one of the configurations 14 to 16, characterized in that a phase shift film is formed between the transparent substrate and the light-shielding film.

(Constitution 19) A method for manufacturing a photomask, characterized by having the following steps: preparing the aforementioned photomask base as in any one of compositions 1 to 11; and forming a resist film on the aforementioned light-shielding film, and removing from the aforementioned resist The resist pattern formed by the etchant film is used as a mask to etch the light-shielding film to form a light-shielding film pattern on the transparent substrate.

(Composition 20) A method for manufacturing a photomask, characterized by having the following steps: preparing the above-mentioned photomask base as in Composition 12; forming a resist film on the above-mentioned light-shielding film, and applying the resist formed from the above-mentioned resist film The agent pattern is used as a mask to etch the light-shielding film to form a light-shielding film pattern on the transparent substrate; and the light-shielding film pattern is used as a mask to etch the semi-transmissive film to form a semi-transparent film on the transparent substrate pattern.

(Configuration 21) A method for manufacturing a photomask, characterized by having the following steps: preparing the above-mentioned photomask base as in configuration 13; forming a resist film on the above-mentioned light-shielding film, and applying the resist formed from the above-mentioned resist film Etching the light-shielding film as a mask to form a light-shielding film pattern on the transparent substrate; and using the light-shielding film pattern as a mask to etch the phase shift film to form a phase shift film on the transparent substrate pattern.

(Configuration 22) A method of manufacturing a display device, characterized by having an exposure step, which is to place the photomask obtained by the manufacturing method of the photomask of any one of configurations 19 to 21 on the exposure device The mask stage is used to expose and transfer at least one mask pattern of the light-shielding film pattern, the semi-transparent film pattern, and the phase shift film pattern formed on the mask to the resist formed on the substrate of the display device. Corrosion agent. [Effects of Invention]

According to the present invention, it is possible to obtain a photomask substrate capable of manufacturing a photomask having excellent pattern accuracy and optical characteristics that can suppress display unevenness during the manufacture of a display device.

Hereinafter, the embodiments of the present invention will be specifically described with reference to the drawings. In addition, the following embodiment is an aspect when the present invention is embodied, and the present invention is not limited to the scope thereof. In addition, the same or equivalent parts may be denoted by the same reference numerals in the drawings, and the description thereof may be simplified or omitted.

<Photomask base> The photomask base of one embodiment of the present invention will be described. The mask substrate of this embodiment is made to expose light of a single wavelength selected from a wavelength region of, for example, 300 nm to 550 nm, or to expose light of multiple wavelengths (for example, j-ray (wavelength: 313 nm), i-ray (Wavelength 365 nm), h-ray (405 nm), g-ray (wavelength 436 nm)) combined light exposure used for display device manufacturing masks. In addition, the numerical range indicated by "～" in this manual refers to the range that includes the numerical value described before and after "～" as the lower limit and the upper limit.

Fig. 1 is a cross-sectional view showing a schematic configuration of a photomask substrate according to an embodiment of the present invention. The mask base 1 is configured by including a transparent substrate 11 and a light shielding film 12. Hereinafter, as a mask base of one embodiment of the present invention, a binary type mask base in which the mask pattern (transfer pattern) of the mask is a light-shielding film pattern will be described.

(Transparent substrate) The transparent substrate 11 is formed of a material that is substantially transparent to exposure light, and it is not particularly limited as long as it is a transparent substrate. Use a substrate material whose transmittance relative to the exposure wavelength is 85% or more, preferably 90% or more. Examples of the material forming the transparent substrate 11 include synthetic quartz glass, soda lime glass, alkali-free glass, and low thermal expansion glass.

The size of the transparent substrate 11 can be appropriately changed according to the required size of the mask used for manufacturing the display device. For example, as the transparent substrate 11, a rectangular substrate can be used, and the length of the short side of the transparent substrate 11 is 330 mm or more and 1620 mm or less. As the transparent substrate 11, for example, sizes of 330 mm × 450 mm, 390 mm × 610 mm, 500 mm × 750 mm, 520 mm × 610 mm, 520 mm × 800 mm, 800 × 920 mm, 850 mm × 1200 can be used. mm, 850 mm×1400 mm, 1220 mm×1400 mm, 1620 mm×1780 mm and other substrates. In particular, it is preferable that the length of the short side of the substrate is 850 mm or more and 1620 mm or less. By using such a transparent substrate 11, a photomask for manufacturing display devices of G7 to G10 is obtained.

(Light-shielding film) The light-shielding film 12 is constituted by laminating a first reflection suppression layer 13, a light blocking layer 14, and a second reflection suppression layer 15 in this order from the transparent substrate 11 side. In addition, in the following description, the transparent substrate 11 side of the mask base 1 is referred to as the back side, and the light shielding film 12 side is referred to as the front side.

The first reflection suppression layer 13 is in the light-shielding film 12, and is provided on the side of the light-shielding layer 14 close to the transparent substrate 11. When pattern transfer is performed using a photomask made by using the photomask base 1, it is placed on Close to the side of the exposure light source. When a photomask is used for exposure processing, exposure light is irradiated from the transparent substrate 11 side (rear side) of the photomask to transfer the pattern transfer image to the resist formed on the substrate for the display device as the transferred body. Etching agent film. At this time, if the exposure light is reflected from the back side of the light-shielding film pattern, it sometimes becomes stray light of the mask pattern as the light-shielding film pattern, which may cause the formation of double images or increase the amount of glare and other transfer image deterioration, or In the vicinity of the overlap of the substrate for the display device, the exposure light above the assumption is irradiated, resulting in display unevenness. The first reflection suppression layer 13 can suppress the reflection of exposure light on the back side of the light-shielding film 12 when pattern transfer is performed using a photomask, thereby suppressing the deterioration of the transferred image and contributing to the improvement of transfer characteristics, and In the vicinity of the overlap of the substrate for the display device, it is possible to suppress the occurrence of display unevenness caused by irradiating the above-presumed exposure light.

The light-shielding layer 14 is provided in the light-shielding film 12 between the first reflection suppression layer 13 and the second reflection suppression layer 15. The light-shielding layer 14 has a function of adjusting the optical density of the light-shielding film 12 to be substantially opaque with respect to exposure light. Here, the term "substantially opaque with respect to exposure light" means a light-shielding property of 3.0 or more in terms of optical density. From the viewpoint of transfer characteristics, the optical density is preferably 4.0 or more, more preferably 4.5 or more. .

The second reflection suppression layer 15 is in the light-shielding film 12 and is provided on the side of the light-shielding layer 14 away from the transparent substrate 11. The second reflection suppression layer 15 can suppress light shielding when a resist film is formed thereon and a specific pattern is drawn on the resist film by drawing light (laser light) of a drawing device (for example, a laser drawing device). The reflection of the front side of the film 12 can improve the CD Uniformity of the resist pattern and the mask pattern formed based on it. In addition, when the second reflection suppression layer 15 is used as a photomask, it is arranged on the side of the substrate for the display device as the transfer object, and can suppress the light reflected by the transfer object from the front surface of the light-shielding film 12 of the photomask The side reflects again and returns to the transferred body to prevent the deterioration of the transferred image and contribute to the improvement of the transfer characteristics. It can also suppress the display caused by the exposure light above the assumed exposure near the overlap of the display device substrate The generation of inequality.

(Material of the light-shielding film) Next, the material of each layer in the light-shielding film 12 will be described. The first reflection suppression layer 13 is composed of a chromium-based material containing chromium, oxygen, and nitrogen. The oxygen in the first reflection suppression layer 13 has an effect of reducing the reflectance of the exposure light from the back side. In addition, the nitrogen in the first reflection suppression layer 13 not only exhibits the effect of reducing the reflectivity of the exposure light from the back side, but also plays a role in the light-shielding film pattern formed by etching (especially wet etching) using a photomask substrate. The profile is close to vertical, and the effect of improving CD uniformity. Furthermore, from the viewpoint of controlling the etching characteristics, carbon or fluorine may be further contained. The light shielding layer 14 is made of a chromium-based material containing chromium and nitrogen. The nitrogen in the light-shielding layer 14 exerts the following effects to reduce the difference in the etching rate with the first reflection-inhibiting layer 13 and the second reflection-inhibiting layer 15 and to make the light shielding formed by etching (especially wet etching) using the mask substrate The cross-section of the film pattern is close to vertical, and the etching time in the light-shielding film 12 (overall) is shortened, and the CD uniformity is improved. Furthermore, from the viewpoint of controlling the etching characteristics, oxygen, carbon, and fluorine may be further contained. The second reflection suppression layer 15 is composed of a chromium-based material containing chromium, oxygen, and nitrogen. The oxygen in the second reflection suppression layer 15 has an effect of reducing the reflectivity of the drawing light from the drawing device on the front side or the reflectivity of the exposure light from the front side. In addition, it exerts an effect of improving the adhesion to the resist film and suppressing side etching due to the penetration of the etchant from the interface between the resist film and the light-shielding film 12. In addition, the nitrogen in the second reflection suppression layer 15 not only has the effect of reducing the reflectivity of the drawing light from the front side and the reflectivity of the exposure light from the front side, but also has the effect of making use of the photomask substrate by etching (especially wet The cross-section of the light-shielding film pattern formed by etching) is close to vertical, and the effect of improving the uniformity of CD. Furthermore, from the viewpoint of controlling the etching characteristics, carbon or fluorine may be further contained.

(Composition of light-shielding film) Next, the composition of each layer in the light-shielding film 12 will be described. In addition, the content rate of each of the following elements shall be the value measured by X-ray photoelectric spectroscopy (XPS).

The light-shielding film 12 is configured in such a way that the first reflection suppression layer 13 contains 25 to 75 atomic% of chromium (Cr), 15 to 45 atomic% of oxygen (O), and 10 to 30 atomic% in terms of content. The light-shielding layer 14 contains 70 to 95 atomic% of chromium (Cr) and 5 to 30 atomic% of nitrogen (N) in terms of content, and the second reflection suppression layer 15 contains 30 to 30 ～75 atomic% of chromium (Cr), 20-50 atomic% of oxygen (O), 5-20 atomic% of nitrogen (N). Preferably, the first reflection suppressing layer 13 contains 50 to 75 atomic% of Cr, 15 to 35 atomic% of O, and 10 to 25 atomic% of N, respectively, in terms of content rate, and the second reflection inhibiting layer 15 is calculated in terms of content rate. They respectively contain 50 to 75 atomic% of Cr, 20 to 40 atomic% of O, and 5 to 20 atomic% of N.

Preferably, the first reflection suppression layer 13 and the second reflection suppression layer 15 each have a region where the content of at least one of O and N elements continuously or stepwise changes in composition along the film thickness direction.

Preferably, the second reflection suppression layer 15 has a region where the O content rate (oxygen content rate) increases toward the light-shielding layer 14 side in the film thickness direction.

Furthermore, it is preferable that the second reflection suppression layer 15 has a region where the N content (nitrogen content) decreases toward the light-shielding layer 14 side in the film thickness direction.

Furthermore, it is preferable that the first reflection suppression layer 13 has a region in which the O content increases and the N content decreases in the transparent substrate 11 facing the film thickness direction.

Moreover, in the photomask substrate 1 and the photomask made therefrom, it is preferable to further reduce the reflectance of the front and back surfaces of the light-shielding film 12 or the light-shielding film pattern, so as to reduce the difference in reflectivity. In order to configure the second reflection suppression layer 15 to have a higher O content rate than the first reflection suppression layer 13, it is preferable that the first reflection suppression layer 13 has an N content rate that is higher than that of the second reflection suppression layer 15 The way to become taller. Specifically, it is preferable that the O content of the second reflection suppression layer 15 is greater than that of the first reflection suppression layer 13 by 5 atomic% or more, and more preferably 10 atomic% or more. Furthermore, it is preferable that the N content of the first reflection suppression layer 13 is greater than that of the second reflection suppression layer 15 by 5 atomic% or more, and more preferably 10 atomic% or more. In addition, when the first reflection suppression layer 13 or the second reflection suppression layer 15 has a compositionally inclined region, the O content rate or the N content rate represents the average concentration in the film thickness direction.

In addition, in the first reflection suppression layer 13, the light shielding layer 14, and the second reflection suppression layer 15, the change in the content rate of each element may be continuous or stepwise, but it is preferably continuous.

(Regarding the bonding state (chemical state)) Preferably, the light shielding layer 14 contains chromium (Cr) and chromium nitride (Cr ₂ N). Preferably, the first reflection suppression layer 13 and the second reflection suppression layer 15 include chromium nitride (CrN), chromium (III) oxide (Cr ₂ O ₃ ), and chromium (VI) oxide (CrO ₃ ).

(Regarding film thickness) In the light-shielding film 12, the respective thicknesses of the first reflection-inhibiting layer 13, the light-shielding layer 14, and the second reflection-inhibiting layer 15 are not particularly limited, and can be based on the required optical density or reflectance of the light-shielding film 12 And adjust appropriately. The thickness of the first reflection suppression layer 13 should be such as to exhibit reflection from the front surface of the first reflection suppression layer 13 and the interface between the first reflection suppression layer 13 and the light shielding layer 14 with respect to the light from the back side of the light shielding film 12 The thickness of the resulting light interference effect is sufficient. On the other hand, the thickness of the second reflection suppression layer 15 needs to be such that the light from the front side of the light-shielding film 12 can be used for the reflection from the front surface of the second reflection suppression layer 15 and the second reflection suppression layer 15 and the light-shielding layer 14 The thickness of the light interference effect caused by the reflection of the interface is sufficient. The thickness of the light-shielding layer 14 may be such that the optical density of the light-shielding film 12 is 3 or more. Specifically, from the viewpoint of making the reflectance of the front and back surfaces with respect to the exposure wavelength to be 10% or less in the light-shielding film 12, and the optical density to be 3.0 or more, for example, the film of the first reflection suppression layer 13 can be made The thickness is 15 nm to 60 nm, the film thickness of the light shielding layer 14 is 50 nm to 120 nm, and the film thickness of the second reflection suppression layer 15 is 10 nm to 60 nm.

<The manufacturing method of the photomask base> Next, the manufacturing method of the above-mentioned photomask base 1 is demonstrated.

(Preparation step) A transparent substrate 11 that is substantially transparent to exposure light is prepared. Furthermore, arbitrary processing steps such as a grinding step and a polishing step may be implemented as needed to make the transparent substrate 11 a flat and smooth main surface. After polishing, cleaning can be performed to remove foreign matter or contamination on the front surface of the transparent substrate 11. As washing, for example, sulfuric acid, sulfuric acid hydrogen peroxide mixture (SPM), ammonia, ammonia water hydrogen peroxide mixture (APM), OH radical washing water, ozone water, warm water, etc. can be used.

(Step of forming the first reflection suppression layer) Next, the first reflection suppression layer 13 is formed on the transparent substrate 11. The formation is performed by reactive sputtering using a sputtering target containing Cr, a reactive gas containing oxygen-based gas, nitrogen-based gas, and a sputtering gas containing rare gas. At this time, as the film forming condition, the flow rate of the reactive gas contained in the sputtering gas is selected to be the flow rate of the metal mode.

Here, the metal mode will be described using FIG. 5. Fig. 5 is a schematic diagram for explaining the film formation mode in the case of forming a thin film by reactive sputtering. The horizontal axis represents the partial pressure (flow rate) ratio of the reactive gas in the mixed gas of the rare gas and the reactive gas, vertical The axis represents the voltage applied to the target. In reactive sputtering, when a target is discharged while introducing a reactive gas such as an oxygen-based gas or a nitrogen-based gas, the state of the discharge plasma changes according to the flow rate of the reactive gas, and accordingly, the film formation rate changes. There are 3 modes based on the difference in film formation speed. Specifically, as shown in FIG. 5, there are a reaction mode in which the supply amount (ratio) of the reactive gas is greater than a certain threshold, a metal mode in which the supply amount (ratio) of the reactive gas is less than the reaction mode, and a metal mode that makes the reactive gas The gas supply amount (ratio) is set in the transition mode between the reaction mode and the metal mode. In the metal mode, by reducing the ratio of the reactive gas, the adhesion of the reactive gas to the target surface is reduced, and the film formation speed can be increased. Moreover, in the metal mode, since the supply amount of the reactive gas is small, for example, a film having a relatively stoichiometric composition can be formed and at least one of O concentration (oxygen concentration) or N concentration (nitrogen concentration) can be formed. Film with lower concentration. That is, it is possible to form a film having a relatively high Cr content and a low O content or N content.

As the conditions of the metal mode for forming the first reflection suppression layer 13, for example, the flow rate of the oxygen-based gas may be 5 to 45 sccm, the flow rate of the nitrogen-based gas may be 30-60 sccm, and the flow rate of the rare gas may be 60～150 sccm. In addition, the target applied power can be set to 2.0 to 6.0 kW, and the target applied voltage can be set to 420 to 430 V.

As the sputtering target, it is sufficient to contain Cr. For example, in addition to chromium metal, chromium-based materials such as chromium oxide, chromium nitride, and chromium oxynitride can be used. As the oxygen-based gas, for example, oxygen (O ₂ ), carbon dioxide (CO ₂ ), nitrogen oxide gas (N ₂ O, NO, NO ₂ ), or the like can be used. Among them, when the self-oxidizing power is high, it is preferable to use oxygen (O ₂ ) gas. In addition, as the nitrogen-based gas, nitrogen (N ₂ ) or the like can be used. As the rare gas, for example, helium, neon, argon, krypton, xenon, etc. may also be used. Furthermore, in addition to the above-mentioned reactive gas, a hydrocarbon-based gas may be supplied. For example, methane gas or butane gas may be used.

In this embodiment, the flow rate of the reactive gas and the power applied to the sputtering target are set to the conditions such as the metal mode, and the sputtering target containing Cr is used to perform the film forming process by reactive sputtering, thereby, A first reflection suppression layer 13 containing 25 to 75 atomic% of Cr, 15 to 45 atomic% of O, and 10 to 30 atomic% of N in terms of content is formed on the transparent substrate 11.

Furthermore, when the first reflection suppression layer 13 is formed as a single film with a uniform composition in the film thickness direction, the film may be formed without changing the type or flow rate of the reactive gas. When the composition is inclined due to the way the upper O content rate or the N content rate changes, the type or flow rate of the reactive gas, the ratio of the oxygen-based gas or the nitrogen-based gas in the reactive gas, etc. can be appropriately changed. In addition, it is also possible to change the arrangement of the gas supply port or the gas supply method.

(Step of forming a light-shielding layer) Next, a light-shielding layer 14 is formed on the first reflection suppression layer 13. The formation is performed by reactive sputtering using a sputtering target contained and a sputtering gas containing a nitrogen-based gas and a rare gas. At this time, as the film forming condition, the flow rate of the reactive gas contained in the sputtering gas is selected to be the flow rate of the metal mode. As the target, what is necessary is just to contain, for example, in addition to chromium metal, chromium-based materials, such as chromium oxide, chromium nitride, and chromium oxynitride, can be used. As the nitrogen-based gas, nitrogen (N ₂ ) or the like can be used. As the rare gas, for example, helium, neon, argon, krypton, xenon, etc. may also be used. Furthermore, in addition to the above-mentioned reactive gas, the oxygen-based gas and the hydrocarbon-based gas described above may be supplied. In this embodiment, the flow rate of the reactive gas and the power applied to the sputtering target are set to the conditions set as the metal mode, and the sputtering target contained is used to perform reactive sputtering, thereby forming the first reflection suppression layer 13 Above, a light-shielding layer 14 containing 70 to 95 atomic% of Cr and 5 to 30 atomic% of N in terms of content is formed.

Furthermore, as the film formation conditions of the light shielding layer 14, for example, the flow rate of the nitrogen-based gas may be 1 to 60 sccm, and the flow rate of the rare gas may be 60 to 200 sccm. In addition, the target applied power can be set to 3.0 to 7.0 kW, and the target applied voltage can be set to 370 to 380 V.

(Step of forming the second reflection suppression layer) Next, the second reflection suppression layer 15 is formed on the light shielding layer 14. This formation system is the same as that of the first reflection suppression layer 13, the flow rate of the reactive gas and the target application power are set to the conditions such as the metal mode, and the sputtering target contained therein is used to form a film by reactive sputtering. Thereby, the second reflection suppression layer 15 containing 30 to 75 atomic% of Cr, 20 to 50 atomic% of O, and 5 to 20 atomic% of N in terms of content is formed on the light shielding layer 14.

As the conditions for the metal mode for forming the second reflection suppression layer 15, for example, the flow rate of the oxygen-based gas may be 8 to 45 sccm, the flow rate of the nitrogen-based gas may be 30-60 sccm, and the flow rate of the rare gas may be 60～150 sccm. In addition, the target applied power can be set to 2.0 to 6.0 kW, and the target applied voltage can be set to 420 to 430 V.

Furthermore, when the composition of the second reflection suppression layer is inclined, as described above, the type or flow rate of the reactive gas, the ratio of the oxygen-based gas or the nitrogen-based gas in the reactive gas, and the like can be appropriately changed.

Based on the above, the mask substrate 1 of this embodiment is obtained.

Furthermore, the film formation of each layer in the light-shielding film 12 can be performed in-situ using an in-line sputtering device. When it is not an in-line sputtering device, sometimes after the film formation of each layer, the transparent substrate 11 must be taken out of the device to expose the transparent substrate 11 to the atmosphere, and the surface of each layer is oxidized or carbonized. As a result, the reflectance of the light shielding film 12 with respect to the exposure light or the etching rate may be changed. Therefore, if it is an in-line sputtering device, the transparent substrate 11 is not taken out of the device and exposed to the atmosphere, and each layer can be continuously formed. Therefore, the introduction of unintended elements into the light-shielding film 12 can be suppressed.

In addition, when the light-shielding film 12 is formed using an in-line sputtering device, the composition of the first reflection-inhibiting layer 13, the light-shielding layer 14, and the second reflection-inhibiting layer 15 has a composition gradient that continuously generates a composition gradient. Area (transition layer), therefore, the cross-section of the light-shielding film pattern formed by etching (especially wet etching) using a mask substrate is smooth and can be close to vertical, so it is preferable.

<The manufacturing method of a photomask> Next, the method of manufacturing a photomask using the said photomask base 1 is demonstrated.

(Formation step of resist film) First, a resist is coated on the second reflection suppression layer 15 in the light-shielding film 12 of the photomask base 1, and a resist film is formed after drying. As the resist, an appropriate one must be selected according to the drawing device used, and either a positive type or a negative type resist can be used.

(Formation step of resist pattern) Next, a specific pattern is drawn on the resist film using a drawing device. Generally, a laser drawing device is used when manufacturing a mask for manufacturing a display device. After drawing, the resist film is developed and rinsed to form a specific resist pattern.

In this embodiment, since the reflectance of the second reflection suppression layer 15 is lowered, it is possible to reduce the reflection of the drawing light (laser light) when the pattern is drawn on the resist film. Thereby, a resist pattern with higher pattern accuracy can be formed, and accordingly, a mask pattern with higher dimensional accuracy can be formed.

(Mask pattern formation step) Next, the light-shielding film 12 is etched by using the resist pattern as a mask to form a mask pattern composed of the light-shielding film pattern. The etching can be either wet etching or dry etching. Generally, wet etching is performed in a photomask for manufacturing a display device. As an etching solution (etchant) used in wet etching, for example, a chromium etching solution containing cerium ammonium nitrate and perchloric acid can be used.

In this embodiment, the composition of each layer is adjusted so that the etching rates of the first reflection suppression layer 13, the light blocking layer 14, and the second reflection suppression layer 15 are the same in the thickness direction of the light-shielding film 12, so that wet etching can be achieved. The latter cross-sectional shape, that is, the cross-sectional shape of the light-shielding film pattern (mask pattern) is close to perpendicular to the transparent substrate 11, and a higher CD uniformity (CD Uniformity) can be obtained.

(Peeling step) Next, the resist pattern is peeled off, and a photomask having a light-shielding film pattern (mask pattern) formed on the transparent substrate 11 is obtained.

Based on the above, the photomask of this embodiment is obtained.

<Method of Manufacturing Display Device> Next, a method of manufacturing a display device using the above-mentioned photomask will be described.

(Preparation steps) First, for the substrate with a resist film on which a resist film is formed on the substrate of the display device, the photomask obtained by the above-mentioned photomask manufacturing method is separated from the projection of the exposure device The optical system is placed on the mask stage of the exposure device in an arrangement in which the resist film formed on the substrate is opposed to each other.

(Exposure step (pattern transfer step)) Next, a resist exposure step is performed, that is, exposure light is irradiated to the photomask, and the pattern is transferred to the resist film formed on the substrate of the display device. The exposure light uses, for example, single-wavelength light (j-ray (wavelength 313 nm), i-ray (wavelength 365 nm), h-ray (wavelength 405 nm), g-ray (wavelength 436 nm) selected from the wavelength region of 300 nm to 550 nm. ), etc.), or composite light containing multiple wavelengths of light (for example, j-ray (wavelength 313 nm), i-ray (wavelength 365 nm), h-ray (405 nm), g-ray (wavelength 436 nm)). In the present embodiment, since the light-shielding film pattern (mask pattern) is used to manufacture a display device (display panel) with a reduced reflectivity on the front and back surfaces, a display device (display panel) without display unevenness can be obtained.

<Effects of this embodiment> According to this embodiment, one or more effects shown below are exhibited.

(a) The mask base 1 of the present embodiment is constructed in such a way that the first reflection suppression layer 13, the light shielding layer 14, and the second reflection suppression layer 15 are laminated to form the light shielding film 12, and the first reflection suppression layer 13 It is a chromium-based material containing chromium, oxygen and nitrogen, and has a composition with a Cr content of 25 to 75 atomic %, an O content of 15 to 45 atomic %, and a N content of 10 to 30 atomic %. The light-shielding layer 14 A chromium-based material containing chromium and nitrogen, with a Cr content of 70 to 95 atomic% and a N content of 5 to 30 atomic%. The second reflection suppression layer 15 is a chromium-based material containing chromium, oxygen and nitrogen , And has a composition in which the Cr content is 30 to 75 atomic %, the O content is 20 to 50 atomic %, and the N content is 5 to 20 atomic %. In addition, the thickness of the first reflection suppression layer 13 and the second reflection suppression layer 15 is set to the maximum or close to the maximum to obtain the optical interference effect. As a result, the reflectance of the front and back surfaces of the photomask substrate 1 with respect to the exposure wavelength can be reduced to 10% or less, respectively. Specifically, in the reflectance spectrum of the front and back sides, the wavelength of the bottom peak with the lowest reflectance can be made 380 nm～480 nm on the relatively high wavelength side, so that the reflectance of light with a wavelength of 380 nm～480 nm is 10% Below, it is preferably 7.5% or less. On the other hand, by setting the light-shielding layer 14 to a specific thickness, the optical density in the light-shielding film 12 can be made 3.0 or more.

(b) In this embodiment, by appropriately changing the composition of the first reflection suppression layer 13 and the second reflection suppression layer 15 within the above range, the back side of the mask base 1 (transparent substrate 11 The reflectance of the side) and the reflectance of the front side (the light-shielding film 12 side). For example, the reflectance of the mask substrate 1 can be adjusted so that the front side is higher than the back side, the front side is the same as the back side, or the back side is higher than the front side. Furthermore, when using a manufactured photomask to expose the transferred body, it is more effective from the viewpoint of suppressing the influence caused by the reflection of the exposure light from the photomask to the light source side (ghosting, etc.) Preferably, the reflectance on the back side is higher than that on the front side. In other words, it is preferable to make the reflectance of the front side (the light shielding film 12 side) of the mask base 1 lower than the reflectance of the back side (the transparent substrate 11 side). Specifically, the wiring pattern of the gate electrode or the source electrode/drain electrode in the TFT (thin-film transistor) array is transferred to the substrate formed on the display device as the transferred body In the case of the resist film, the aperture ratio of the light-shielding film pattern of the mask becomes more than 50%, so the amount of exposure light passing through the mask becomes higher, so it is easy to generate glare due to the return light of the exposure light from the side of the transferred body. Therefore, by making the reflectance of the front and back of the light-shielding film 12 of the mask substrate 1 with respect to the exposure wavelength to be 10% or less, and the reflectance of the front side of the light-shielding film 12 is lower than the reflectance of the back side, It can reduce the effect of glare and prevent CD errors when using photomasks to make display devices.

(c) In this embodiment, the first reflection suppression layer 13, the light blocking layer 14, and the second reflection suppression layer 15 constituting the light-shielding film 12 are in the above composition range, so that the etching rate can be reduced. The concentration of O or N, which increases the etching rate, suppresses the difference in the etching rate of each layer. Thereby, the cross-sectional shape of the mask pattern when the light-shielding film 12 of the photomask base 1 is etched can be made close to perpendicular to the transparent substrate 11. Specifically, in the cross-sectional shape of the mask pattern, when the angle formed by the side surface formed by etching and the transparent substrate 11 is set to Θ, Θ can be made within the range of 90°±30°. In addition, the cross-sectional shape of the mask pattern can be made close to vertical, and the etching residue of the first reflection suppression layer 13 or the erosion (so-called undercut) of the first reflection suppression layer 13 and the second reflection suppression layer 15 can be suppressed. Etching etc. As a result, the CD uniformity in the mask pattern (light-shielding film pattern) can be improved, and a high-precision mask pattern below 100 nm can be formed.

(d) In this embodiment, the light-shielding film 12 is formed by making the etching rates of the first reflection-inhibiting layer 13, light-shielding layer 14, and second reflection-inhibiting layer 15 of the light-shielding film 12 uniform regardless of the etching The length of time, the concentration of the etching solution, and the temperature of the etching solution can stably ensure the verticality of the cross-sectional shape. For example, when the just-etching time of the light-shielding film 12 is set to T, even when the etching time is 1.5×T and the over-etching is performed, the same verticality as when the etching time is set to T can be obtained. Specifically, the difference between the angle θ1 formed by the cross-section of the light-shielding film pattern when the etching time is T and the angle θ2 formed by the cross-section after the etching time is 1.5×T can be set to 10° or less . Also, similarly, when the concentration of the etching solution is increased and when the concentration of the etching solution is decreased, the difference in the angle formed by the cross section of the light-shielding film pattern can be 10° or less. Also, similarly, when the temperature of the etching solution is increased (for example, 42°C) and when the temperature of the etching solution is decreased (for example, room temperature 23°C), the higher the temperature of the etching solution, the higher the etching rate. It is high, but the difference in the angle formed by the cross section of the light-shielding film pattern can be 10° or less. In addition, the "just etching time" refers to the etching time until the light-shielding film 12 is etched in the film thickness direction and the front surface of the transparent substrate 11 starts to be exposed.

(e) Preferably, in the light-shielding film 12, the first reflection suppression layer 13 and the second reflection suppression layer 15 are chromium-based materials containing chromium, oxygen, and nitrogen, and the first reflection suppression layer 13 respectively contains 50 to 75 atomic% of Cr, 15 to 35 atomic% of O, 10 to 25 atomic% of N, the second reflection suppression layer 15 contains 50 to 75 atomic% of Cr and 20 to 40 atomic% of O, 5-20 atomic% of N.

In the first reflection suppression layer 13 and the second reflection suppression layer 15, by further reducing the O content, it is possible to suppress an excessive increase in the etching rate due to O in the layers containing these. Therefore, in order to make the etching rate of each layer of the first reflection suppression layer 13, the light blocking layer 14, and the second reflection suppression layer 15 constituting the light shielding film 12 uniform, the content rate of carbon (C) which is blended in the light shielding layer 14 can be reduced. Alternatively, the light-shielding layer 14 does not contain C but does not contain carbon. As a result, the Cr content in the light shielding layer 14 can be increased, and the optical density (OD) can be maintained high.

On the other hand, in the first reflection suppression layer 13 and the second reflection suppression layer 15, by further reducing the N content, it is possible to suppress an excessive increase in the etching rate due to N in the layers containing these. Therefore, the content of N contained in the light-shielding layer 14 can be reduced for the purpose of making the etching rates of the first reflection-inhibiting layer 13, the light-shielding layer 14, and the second reflection-inhibiting layer 15 uniform. As a result, the Cr content in the light shielding layer 14 can be increased, and the optical density (OD) can be maintained high.

(f) It is preferable that the first reflection suppression layer 13 and the second reflection suppression layer 15 each have a region where the content of at least one element of O and N changes continuously or stepwise along the film thickness direction. By changing the composition of each layer of the first reflection suppression layer 13 and the second reflection suppression layer 15, it is possible to locally introduce O or N to each layer to become a region with a higher content rate, and to remove the O or N in each layer. The average content rate is maintained low. Thereby, the reflectivity of the front side and the back side of the photomask substrate 1 can be maintained low.

In addition, in each of the first reflection suppression layer 13, the light shielding layer 14, and the second reflection suppression layer 15 constituting the light-shielding film 12, if the O content increases, the etching rate increases excessively, or if the N content increases, The etching rate is excessively increased, and by reducing the content of O or N, the difference in the etching rate of each layer caused by the inclusion of these elements can be suppressed. That is, the deviation of the etching rate between the first reflection suppression layer 13 and the second reflection suppression layer 15 and the light shielding layer 14 can be suppressed. As a result, in order to make the etching rate of each layer of the first reflection suppression layer 13, the light blocking layer 14, and the second reflection suppression layer 15 constituting the light blocking film 12 uniform, the N or carbon contained in the light blocking layer 14 can be reduced, or The light shielding layer 14 does not contain carbon but does not contain carbon. As a result, the Cr content in the light shielding layer 14 can be increased, and the optical density (OD) can be maintained high.

(g) It is preferable that the second reflection suppression layer 15 has a region where the O content increases toward the light shielding layer 14 side in the film thickness direction. Thereby, in the second reflection suppression layer 15, the O content in the interface portion with the light shielding layer 14 is locally increased, and the average O content in the film thickness direction is decreased. As a result, a desired reflectance can be obtained on the front side (second reflection suppression layer 15) of the light-shielding film 12, and erosion due to excessive etching of the interface can be suppressed.

(h) Preferably, the second reflection suppression layer 15 has a region where the N content decreases toward the light-shielding layer 14 side in the film thickness direction. Thereby, in the second reflection suppression layer 15, the average N content in the film thickness direction is maintained at a certain level, and the N content in the interface portion with the light shielding layer 14 is locally lowered. As a result, it is possible to suppress erosion due to excessive etching of the interface between the second reflection suppression layer 15 and the light shielding layer 14.

(i) Preferably, the first reflection suppression layer 13 has a region where the O content increases and the N content decreases in the transparent substrate 11 facing the film thickness direction. In the first reflection suppression layer 13, by increasing the O content and decreasing the N content of the transparent substrate 11 in the film thickness direction, the etching rate can be gradually reduced toward the transparent substrate 11. Thereby, the erosion of the interface between the first reflection suppression layer 13 and the transparent substrate 11 can be suppressed, and the CD uniformity of the mask pattern can be further improved.

(j) Preferably, the second reflection suppression layer 15 is configured to have a higher O content than the first reflection suppression layer 13. Specifically, it is preferable that the O content of the second reflection suppression layer 15 is greater than that of the first reflection suppression layer 13 by 5 atomic% or more, and more preferably 10 atomic% or more. In addition, the first reflection suppression layer 13 is configured to have a higher N content than the second reflection suppression layer 15. Specifically, it is preferable that the N content of the first reflection suppression layer 13 is greater than that of the second reflection suppression layer 15 by 5 atomic% or more, and more preferably 10 atomic% or more. According to the research conducted by the inventors, when the first reflection suppression layer 13 and the second reflection suppression layer 15 are formed of the same material, although the composition is the same, the reflectance on the front side tends to be higher than that on the back side. . Therefore, the composition ratio (O content rate, N content rate) of each layer of the first reflection suppression layer 13 and the second reflection suppression layer 15 was further studied. As a result, it was found that the first reflection suppression layer 13 and the second reflection suppression layer The composition ratio (O content rate, N content rate) of the layer 15 is as described above, so that the reflectance on the back side can be the same as the front side, or can be lower than the front side. By changing the composition ratio (O content rate, N content rate) of each layer in this way, the reflectance of the front and back surfaces can be controlled.

(k) According to this embodiment, the light shielding layer 14 is preferably made of a chromium-based material in a bonding state (chemical state) of chromium _{(Cr) and chromium nitride (Cr 2 N).} By making the light-shielding layer 14 contain a _{chromium-based material in the bonding state (chemical state) with Cr 2} N, the excessive development of the etching rate when the light-shielding layer 14 contains a specific amount of N can be suppressed, and the pattern of the light-shielding film The cross-sectional shape is close to vertical.

(l) According to this embodiment, it is preferable that the first reflection suppression layer 13 and the second reflection suppression layer 15 include chromium nitride (CrN), chromium (III) oxide (Cr ₂ O ₃ ), and oxide. Chromium (VI) (CrO ₃ ) bonding state (chemical state) of chromium-based materials. By making the first reflection suppression layer 13 and the second reflection suppression layer 15 contain plural chromium oxides of _{Cr 2} O _{3 and CrO 3} , the reflectance of the front and back surfaces of the light-shielding film 12 can be effectively reduced. In addition, since the first reflection suppression layer 13 and the second reflection suppression layer 15 contain CrN chromium nitride, the excessive decrease in the etching rate caused by the chromium oxide can be suppressed, so that the cross-sectional shape of the light-shielding film pattern can be close to vertical .

(m) According to this embodiment, the first reflection suppression layer 13 and the second reflection suppression layer 15 are combined by using a sputtering target containing Cr and a sputtering gas containing oxygen-based gas, nitrogen-based gas, and rare gas Reactive sputtering is used to form a film, and the light shielding layer 14 is formed by reactive sputtering using a sputtering target containing Cr and a sputtering gas containing a nitrogen-based gas and a rare gas. Moreover, as the film forming conditions for these reactive sputtering, the flow rate of the reactive gas contained in the sputtering gas is selected to be the flow rate of the metal mode. Thereby, it is easy to adjust each layer of the first reflection suppression layer 13, the light blocking layer 14, and the second reflection suppression layer 15 constituting the light shielding film 12 to the above composition range, and the reflectance of the front and back surfaces of the light shielding film 12 can be effectively reduced , And the cross-sectional shape of the light-shielding film pattern after patterning the light-shielding film 12 can be close to vertical.

(n) When forming the respective layers of the first reflection suppression layer 13 and the second reflection suppression layer 15 by reactive sputtering, it is preferable to use oxygen (O ₂ gas) as the oxygen-based gas. According to the O ₂ gas, since the oxidizing power is higher than other oxygen-based gases, even when the metal mode is selected for film formation, each layer can be more reliably adjusted to the above-mentioned composition range. Thereby, the reflectivity of the front and back surfaces of the light-shielding film 12 can be effectively reduced, and the cross-sectional shape of the light-shielding film pattern after the light-shielding film 12 is patterned can be made close to vertical.

(o) According to the photomask substrate 1 of this embodiment, since the reflectance on the front side is low, when a resist film is provided on the light-shielding film 12 and the resist pattern is formed through the drawing and development steps, it can be Reduce the reflection of the front surface of the shading film 12 of the drawing light. Thereby, the dimensional accuracy of the resist pattern can be improved, and the dimensional accuracy of the light-shielding film pattern of the mask formed later can be improved.

(p) The photomask made from the photomask substrate 1 of this embodiment has a high-precision light-shielding film pattern, and the reflectivity of the front and back of the light-shielding film pattern is reduced. Therefore, it can be obtained when the pattern is transferred to the object to be transferred. Higher transfer characteristics.

(q) Also, in this embodiment, even when a rectangular substrate with a short side length of 850 mm or more and 1620 mm or less is used as the transparent substrate 11, the mask base 1 is enlarged. The light-shielding film 12 is formed in a way that the etching rate in the film thickness direction is uniform, so the CD uniformity of the mask pattern obtained by etching the light-shielding film 12 can be maintained high.

(r) In addition, the photomask of this embodiment can make the reflectance of the front and back of the light-shielding film pattern with respect to the light selected from the wavelength range of 300 nm to 550 nm to be 10% or less, preferably 7.5% Hereinafter, it is more preferably 5% or less. Therefore, even when the exposure light intensity is increased by exposing a composite light including i-rays, h-rays, and g-rays, it can also be formed for the transferred body. Transfer patterns with higher precision. Furthermore, in the vicinity of the overlap of the transferred body (for example, a display panel), it is possible to prevent display unevenness due to exposure of the above-presumed exposure light. Furthermore, as the exposure light, there is a composite light including light of a plurality of wavelengths selected from the wavelength region of 300 nm to 550 nm, or a certain wavelength region is selected by cutting a certain wavelength region from the wavelength region of 300 nm to 550 nm using filters, etc. The monochromatic light includes, for example, composite light including j-ray with a wavelength of 313 nm, i-ray with a wavelength of 365 nm, h-ray with a wavelength of 405 nm, and g-ray with a wavelength of 436 nm, or monochromatic light of i-ray.

<Other Embodiments> As mentioned above, one embodiment of the present invention has been specifically described, but the present invention is not limited to the above-mentioned embodiment, and can be appropriately changed without departing from the gist of the present invention.

In the above-mentioned embodiment, the case where the light-shielding film 12 is directly provided on the transparent substrate 11 has been described, but the present invention is not limited to this. For example, it may also be a mask base in which a semi-transmissive film with a lower optical density than the light-shielding film 12 is disposed between the transparent substrate and the light-shielding film 12. The mask substrate can be used as a mask substrate for a gray tone mask or a gradation mask with the effect of reducing the number of masks used in manufacturing a display device. The gray-tone mask or the mask pattern in the gradation mask becomes a semi-transparent film pattern and/or a light-shielding film pattern. In addition, instead of the semi-transmissive film, a phase shift film that shifts the phase of transmitted light may be provided on the mask base between the transparent substrate 11 and the light shielding film 12. The photomask substrate can be used as a phase shift mask with a higher pattern resolution effect brought by the phase shift effect. The mask pattern in the phase shift mask becomes a phase shift film pattern, or a phase shift film pattern and a light-shielding film pattern. The above-mentioned semi-transmissive film and phase shift film adopt materials having etching selectivity to the chromium-based material constituting the light-shielding film 12. As such materials, metal silicide-based materials containing molybdenum (Mo), zirconium (Zr), titanium (Ti), tantalum (Ta), and silicon (Si) can be used, and then used containing oxygen, nitrogen, carbon, or fluorine At least any one of the materials. For example, using MoSi, ZrSi, TiSi, TaSi and other metal silicides, oxides of metal silicides, nitrides of metal silicides, oxynitrides of metal silicides, carbon nitrides of metal silicides, and carbon of metal silicides Oxide, metal silicide carbide oxide nitride. Furthermore, these semi-transmissive films or phase shift films may also be laminated films composed of the above-mentioned films exemplified as functional films. The transmittance of the semi-transparent film and the phase shift film with respect to the exposure wavelength of the exposure light can be appropriately adjusted within the range of 1 to 80%. In the combination of the light-shielding film of the present invention, the transmittance of the semi-transparent film and the phase shift film with respect to the exposure wavelength of the exposure light is preferably 20 to 80%. By selecting a semi-transmissive film and a phase shift film with a transmittance of 20 to 80% relative to the exposure wavelength of the exposure light, the light-shielding film of the present invention can be combined to form a laminated layer of the semi-light film and the light-shielding film The reflectance with respect to the exposure wavelength of the back surface of the film or the laminated film in which the phase shift film and the light-shielding film are formed is 40% or less, and more preferably 30% or less.

In addition, in the above-mentioned embodiment, the case where the first reflection suppression layer 13 and the second reflection suppression layer 15 are each one layer has been described, but the present invention is not limited to this. For example, each layer may be a plural number of two or more layers.

In addition, in the above-mentioned embodiment, an etching mask film made of a material having an etching selectivity with the light-shielding film 12 may also be formed on the light-shielding film 12.

In addition, in the above-mentioned embodiment, an etching stop film made of a material having etching selectivity with the light-shielding film may also be formed between the transparent substrate 11 and the light-shielding film 12. The above-mentioned etching mask film and the etching stop film are composed of a material having an etching selectivity with respect to a chromium-based material constituting the light-shielding film 12. Examples of such materials include metal silicide-based materials containing molybdenum (Mo), zirconium (Zr), titanium (Ti), tantalum (Ta), and silicon (Si), or Si, SiO, SiO ₂ , SiON, and Si ₃ N ₄ and other silicon-based materials. [Example]

Next, the present invention will be described in more detail based on examples, but the present invention is not limited to these examples.

<Example 1> (Fabrication of the photomask base) In this example, using an in-line sputtering device, according to the sequence shown in the above embodiment, the substrate size as shown in Figure 1 is 1220 mm×1400 The first reflection suppression layer, the light shielding layer, and the second reflection suppression layer are laminated on a transparent substrate of mm to form a mask base with a light shielding film.

The film forming condition of the first reflection suppression layer is to set the sputtering target as the Cr sputtering target, and the flow rate of the reactive gas is to become the metal mode so that the flow rate of the oxygen (O ₂ ) gas is selected from the range of 5 to 45 sccm , The flow rate of nitrogen (N ₂ ) gas is selected from the range of 30-60 sccm, the flow rate of argon (Ar) gas is selected from the range of 60-150 sccm, and the target applied power is set to 2.0-6.0 kW, and the target The applied voltage is set to the range of 420～430 V. Furthermore, the substrate transport speed during the film formation of the first reflection suppression layer was set to 350 mm/min.

The film-forming conditions of the light-shielding layer are set as the sputtering target as the Cr sputtering target, and the flow rate of the reactive gas is changed to the metal mode so that the flow rate of the nitrogen (N ₂ ) gas is selected from the range of 1 to 60 sccm, so that the argon The flow rate of (Ar) gas is selected from the range of 60 to 200 sccm, and the target applied power is set to 3.0 to 7.0 kW, and the applied voltage is set to the range of 370 to 380 V. Furthermore, the substrate conveying speed during the film formation of the light-shielding layer was set to 200 mm/min.

The film forming condition of the second reflection suppression layer is to set the sputtering target as the Cr sputtering target, and the flow rate of the reactive gas is to become the metal mode so that the flow rate of the oxygen (O ₂ ) gas is selected from the range of 8 to 45 sccm , The flow rate of nitrogen (N ₂ ) gas is selected from the range of 30-60 sccm, the flow rate of argon (Ar) gas is selected from the range of 60-150 sccm, and the target applied power is set to 2.0-6.0 kW, and the target The applied voltage is set in the range of 420 to 430 V. Furthermore, the substrate transport speed during the film formation of the second reflection suppression layer was set to 300 mm/min.

Regarding the obtained light-shielding film of the mask base, the composition in the film thickness direction was measured by X-ray photoelectron spectroscopy (XPS). As a result, it was confirmed that each layer in the light-shielding film had the composition distribution shown in FIG. 2. 2 is a graph showing the result of composition analysis in the film thickness direction of the mask substrate of Example 1. The horizontal axis represents the sputtering time, and the vertical axis represents the element content [atom %]. The sputtering time indicates the depth from the surface of the shading film.

In Figure 2, the area from the surface to the depth of about 5 min (minutes) is the surface natural oxide layer, and the area from the depth of about 5 min (minutes) to the depth of about 16 min (minutes) is the second reflection suppression layer. The region from a depth of about 16 min (minutes) to a depth of about 40 min (minutes) is a transition layer, and the region from a depth of about 40 min (minutes) to a depth of about 97 min (minutes) is a light-shielding layer, from a depth of about 97 The area from min (minute) to the depth of about 124 min (minute) is the transition layer, and the area from the depth of about 124 min (minute) to the depth of about 132 min (minute) is the first reflection suppression layer, and the distance from the depth is about 132 min. The area in (minutes) is a transparent substrate. Furthermore, the film thickness of the light-shielding film measured by a film thickness meter is 198 nm, and the above-mentioned surface natural oxide layer, the second reflection suppression layer, the transition layer, the light-shielding layer, the transition layer, and the first reflection suppression layer are each film The thickness of the natural oxide layer on the thick surface is about 4 nm, the second reflection suppression layer is about 21 nm, the transition layer is about 35 nm, the light shielding layer is about 88 nm, the transition layer is about 39 nm, and the first reflection suppression layer is about 11 nm.

As shown in FIG. 2, the first reflection suppression layer is a CrON film, which contains 55.4 atomic% of Cr, 20.8 atomic% of N, and 23.8 atomic% of O. The content of these elements is measured in the part where N in the first reflection suppression layer becomes the peak (the area where the sputtering time is 123 min (minutes)). The first reflection suppression layer has an inclined composition as shown in FIG. 2 and has a transparent substrate facing the film thickness direction, where the O content increases and the N content decreases. Furthermore, in the first reflection suppression layer, the average content of each element in the film thickness direction is 57 atomic% for Cr, 18 atomic% for N, and 25 atomic% for O.

The light-shielding layer is a CrN film, which contains 92.0 atomic% of Cr and 8.0 atomic% of N. The content of these elements is measured in the central part (the area where the sputtering time is 69 min (minutes)) in the film thickness direction of the light-shielding layer. Furthermore, in the light-shielding layer, the average content of each element in the film thickness direction is 91 atomic% for Cr and 9 atomic% for N.

The second reflection suppression layer is a CrON film, which contains 50.7 atomic% of Cr, 12.2 atomic% of N, and 37.1 atomic% of O. The content of these elements is measured in the central part of the area where O increases in the second reflection suppression layer (the area where the sputtering time is 16 min (minutes)). The second reflection suppression layer has a sloped composition as shown in FIG. 2 and has a portion where the O content increases and the N content decreases toward the light-shielding layer side in the film thickness direction. Furthermore, in the second reflection suppression layer, the average content of each element in the film thickness direction is 52 atomic% for Cr, 17 atomic% for N, and 31 atomic% for O. In addition, it is considered that a natural oxidation layer on the surface is formed by exposure to the atmosphere on the surface of the second reflection suppression layer, and because this layer is oxidized or carbonized, high O content and C content are detected.

Furthermore, based on the XPS measurement result, the bonding state (chemical state) of each layer of the first reflection suppression layer, the light shielding layer, and the second reflection suppression layer constituting the light-shielding film was analyzed by spectrum. As a result, the first reflection suppression layer and the second reflection suppression layer contain chromium nitride (CrN), chromium oxide (III) (Cr ₂ O ₃ ), and chromium oxide (VI) (CrO ₃ ), and contain chromium, oxygen, and Nitrogen-based chromium materials (chromium compounds). In addition, the light-shielding layer is a _{chromium-based material (chromium compound) containing chromium (Cr) and chromium nitride (Cr 2} N), and containing chromium and nitrogen.

(Evaluation of the photomask substrate) Regarding the photomask substrate of Example 1, the optical density of the light-shielding film and the reflectivity of the front and back surfaces of the light-shielding film were evaluated by the method shown below.

Regarding the mask substrate of Example 1, the optical density of the light-shielding film was measured by a spectrophotometer ("SolidSpec-3700" manufactured by Shimadzu Corporation). As a result, the g-ray ( The wavelength is 436 nm) 5.0. In addition, the reflectance of the front and back of the light-shielding film was measured with a spectrophotometer ("SolidSpec-3700" manufactured by Shimadzu Corporation). Specifically, the reflectance on the second reflection suppression layer side of the light-shielding film (front reflectance) and the reflectance on the transparent substrate side of the light-shielding film (back reflectance) were measured with a spectrophotometer. As a result, the reflectance spectrum shown in Fig. 3 was obtained. Fig. 3 shows the reflectance spectrum of the front and back of the photomask substrate of Example 1. The horizontal axis represents the wavelength [nm], and the vertical axis represents the reflectance [%]. As shown in Fig. 3, in the photomask substrate of Example 1, it was confirmed that the bottom peak wavelength of the reflectance spectrum of the front and back sides can be around 436 nm, and the reflectance can be greatly reduced compared to light of a wide range of wavelengths. Specifically, in the wavelength of 365 nm ~ 436 nm, the front reflectance of the shading film is 10.0% or less (7.7% (wavelength 365 nm), 1.8% (wavelength 405 nm), 1.1% (wavelength 413 nm), 0.3% (Wavelength 436 nm)), the back surface reflectance of the shading film is below 7.5% (6.2% (wavelength 365 nm), 4.7% (wavelength 405 nm), 4.8% (wavelength 436 nm)). It has been confirmed that the reflectance of the front and back of the light shielding film can be reduced to less than 10% at a wavelength of 365 nm to 436 nm, especially with regard to the reflectance of light with a wavelength of 436 nm, the front reflectance can be 0.3%, and the back The reflectivity is 4.8%.

(Evaluation of light-shielding film pattern) Using the mask base of Example 1, a light-shielding film pattern was formed on a transparent substrate. Specifically, after forming a phenolic-based positive resist film on the light-shielding film on the transparent substrate, laser drawing (wavelength 413 nm) and development are performed to form a resist pattern. Then, the resist pattern is used as a mask and wet etching is performed with a chromium etching solution to form a light-shielding film pattern on the transparent substrate. The evaluation of the light-shielding film pattern was performed by forming a 1.9 μm line and gap pattern and observing the cross-sectional shape of the light-shielding film pattern with a scanning electron microscope (SEM). As a result, as shown in FIG. 4, it was confirmed that the cross-sectional shape was made close to vertical. 4 is a diagram for explaining the verticality of the cross-sectional shape of the light-shielding film pattern realized by wet etching with respect to the photomask substrate of Example 1, and respectively shows that it is based on the just etching time (JET) (100%) , Make the etching time 110%, 130%, 150% and the cross-sectional shape after etching. In FIG. 4, it is confirmed that a light-shielding film pattern and a resist film pattern are laminated on the transparent substrate. When the side of the light-shielding film pattern is JET 100%, the angle formed with the transparent substrate is 70°. It is confirmed that the angle formed is within the range of 60°～80° even when the etching time is 110%, 130%, and 150% of JET. Regardless of the etching time, the cross-sectional shape of the light-shielding film pattern can be made The stable terrain becomes vertical.

As in Example 1 above, regarding the light-shielding film of the mask base, the first reflection-inhibiting layer, the light-shielding layer, and the second reflection-inhibiting layer are laminated from the transparent substrate side so that each layer has a specific composition. , The reflectance of the front and back sides can be reduced in a wide range of wavelengths, and the cross-sectional shape of the light-shielding film pattern patterned by wet etching can be formed to be vertical.

(Making of the photomask) Next, using the photomask substrate of Example 1 to manufacture a photomask. First, a phenolic-based positive resist is formed on the light-shielding film of the mask substrate. Then, use a laser drawing device to draw the pattern of the circuit pattern for the TFT panel on the resist film, and then develop and rinse to form a specific resist pattern (the minimum line width of the above circuit pattern is 0.75 μm ). Then, the resist pattern is used as a mask, and a chromium etching solution is used to pattern the light-shielding film by wet etching. Finally, the resist pattern is peeled off by the resist stripping liquid to obtain a light-shielding formed on the transparent substrate. The mask of the film pattern (mask pattern). The CD uniformity of the light-shielding film pattern of the mask was measured by "SIR8000" manufactured by Seiko Nano Technology Co., Ltd. The measurement of CD uniformity is about the area of 1100 mm×1300 mm excluding the peripheral area of the substrate, and the measurement is carried out at the position of 11×11. As a result, the CD uniformity was 100 nm, and the CD uniformity of the obtained photomask was good.

(Fabrication of LCD Panel) The photomask fabricated in Example 1 was set on the mask stage of the exposure device, and the resist film was formed on the substrate for the display device (TFT) to be transferred Pattern exposure is performed to fabricate a TFT array. As the exposure light, composite light with a wavelength of 300 nm or more and 550 nm or less including i-ray with a wavelength of 365 nm, h-ray with a wavelength of 405 nm, and g-ray with a wavelength of 436 nm is used. Combine the produced TFT array with color filters, polarizers, and backlight to produce a TFT-LCD panel. As a result, a TFT-LCD panel with no display unevenness was obtained.

<Example 2> (Production of a photomask base) In this example, a photomask base was manufactured in the same manner as in Example 1, except that a semi-transparent film was formed between the transparent substrate and the light-shielding film. Specifically, after forming a translucent film on a transparent substrate of 1220 mm×1400 mm, the first reflection suppression layer, the light shielding layer, and the second reflection suppression layer were laminated under the same conditions as in Example 1, thereby manufacturing The mask substrate of Example 2. The semi-transparent film is formed by using the sputtering target as the MoSi sputtering target, and the molybdenum silicide nitriding is formed by reactive sputtering using a mixed gas of _{argon (Ar) gas and nitrogen (N 2) gas} Film (MoSiN). The semi-transmissive film is in i-ray (wavelength 365 nm), and the composition ratio and film thickness are appropriately adjusted so that the transmittance becomes 40%. Next, in the same manner as in Example 1, a light shielding film composed of a first reflection suppressing layer, a light shielding layer, and a second reflection suppressing layer was formed on the above-mentioned semi-transparent film to manufacture a mask base of Example 2.

(Evaluation of photomask substrate) Regarding the photomask substrate of Example 2, the optical density of the laminated film composed of the semi-transmissive film and the light-shielding film and the reflectivity of the front and back surfaces were evaluated by the same method as the above-mentioned Example 1 . As a result, the optical density of the laminated film in the g-ray (wavelength 436 nm) which is the wavelength region of the exposure light is 5.0 or more. In addition, in the wavelength of 365 nm to 436 nm, the reflectance (frontal reflectance) of the light-shielding film side of the laminated film is 10.0% or less (7.7% (wavelength 365 nm), 1.8% (wavelength 405 nm), 1.1% (wavelength 413 nm), 0.3% (wavelength 436 nm)), the reflectance of the semi-transmissive film side (back surface reflectance) is 30.0% or less (27.4% (wavelength 365 nm), 22.5% (wavelength 405 nm), 20.1% ( Wavelength 436 nm)).

(Making of the photomask) Next, using the photomask substrate of Example 2 to manufacture a photomask. The photomask is formed with a semi-transmissive film pattern on a transparent substrate, a light-shielding film pattern is formed on the semi-transparent film pattern, and is provided with a transfer pattern including a light-transmitting part, a light-shielding part, and a semi-light-transmitting part. The mask of Example 2 is manufactured by the manufacturing method of the gray tone mask described in Patent No. 4934236. The CD uniformity of the semi-transmissive film pattern and the light-shielding film pattern of the obtained mask is good.

(Production of LCD panel) Using the photomask produced in this Example 2, an LCD panel was produced in the same manner as in Example 1. As a result, a TFT-LCD panel with no display unevenness was obtained. Furthermore, as the manufacturing method of the photomask of Example 2, it can be manufactured by the manufacturing method of the photomask described in Patent No. 5605917, and the semi-transparent film pattern and light-shielding film of the photomask obtained by this method The CD uniformity of the film pattern is also good. Moreover, a TFT-LCD panel with less display unevenness is obtained.

<Comparative Example 1> As a comparative example, a mask base provided with a light-shielding film was fabricated on a transparent substrate with a substrate size of 1220 mm×1400 mm. The first reflection suppression layer, the light shielding layer, and the second reflection suppression layer were laminated.

The film forming condition of the first reflection suppression layer is to set the sputtering target as the Cr sputtering target, and the flow rate of the reactive gas is to become the reaction mode so that the flow rate of the oxygen (O ₂ ) gas is selected from the range of 150 to 300 sccm , The flow rate of nitrogen (N ₂ ) gas is selected from the range of 150 to 300 sccm, _{the flow rate of methane (CH 4} ) gas is selected from the range of 5 to 15 sccm, and the flow rate of argon (Ar) gas is selected from 100 to 150 sccm Select the range, and set the target applied power to the range of 2.0 to 7.0 kW. In addition, the substrate transport speed during the film formation of the first reflection suppression layer was set to 200 mm/min, and the film formation was performed three times.

The film-forming conditions of the light-shielding layer are set as the sputtering target as the Cr sputtering target, and the flow rate of the reactive gas is changed to the metal mode so that the flow rate of the nitrogen (N ₂ ) gas is selected from the range of 1 to 60 sccm, so that the argon The flow rate of (Ar) gas is selected from the range of 60 to 200 sccm, and the target applied power is set to the range of 5.0 to 8.0 kW. Furthermore, the substrate conveying speed during the film formation of the light-shielding layer was set to 200 mm/min.

The film forming condition of the second reflection suppression layer is to set the sputtering target as the Cr sputtering target, and the flow rate of the reactive gas is such that the flow rate of the oxygen (O ₂ ) gas is selected from the range of 150 to 300 so that it becomes the reaction mode. The flow rate of nitrogen (N ₂ ) gas is selected from the range of 150 to 300 sccm, _{the flow rate of methane (CH 4} ) gas is selected from the range of 5 to 15 sccm, and the flow rate of argon (Ar) gas is selected from 100 to 150 sccm. Select the range, and set the target applied power to the range of 2.0 to 7.0 kW. In addition, the substrate transport speed during the film formation of the second reflection suppression layer was set to 200 mm/min, and the film formation was performed three times. The thickness of the light-shielding film measured by a film thickness meter was 206 nm. Furthermore, the thickness of each of the surface natural oxide layer, the second reflection suppression layer, the light shielding layer, and the first reflection suppression layer is about 3 nm, the second reflection suppression layer is about 51 nm, and the light shielding layer is about 101 nm. The reflection suppression layer is about 51 nm. Furthermore, between the second reflection suppression layer and the light-shielding layer, and between the light-shielding layer and the first reflection suppression layer, a transition layer in which the composition of each element is continuously inclined is formed.

Regarding the light-shielding film of the mask base of Comparative Example 1, the content rate of the elements contained in each layer was measured, and the results are as follows. In addition, the content rate of each layer shown below represents the average content rate of each element in the film thickness direction. The first reflection suppression layer is a CrON film, containing 45 atomic% of Cr, 3 atomic% of N, and 52 atomic% of O. The light-shielding layer is a CrN film, containing 78 atomic% of Cr and 22 atomic% of N. The second reflection suppression layer is a CrON film, containing 45 atomic% of Cr, 3 atomic% of N, and 52 atomic% of O.

In the same manner as in Example 1, regarding the mask substrate of Comparative Example 1, the optical density of the light-shielding film and the reflectance of the front and back surfaces of the light-shielding film were measured. As a result, the optical density of the light-shielding film is 3.5% in the g-ray (wavelength of 436 nm) as the wavelength region of the exposure light, and 4.5% in the i-ray (wavelength of 365 nm). In addition, in the wavelength of 365 nm～436 nm, the frontal reflectance of the light-shielding film is 5.0% or less (4.5% (wavelength 365 nm), 4.0% (wavelength 405 nm), 3.5% (wavelength 436 nm)). The back reflectance is 7.5% or less (5.5% (wavelength 365 nm), 6.5% (wavelength 405 nm), 7.5% (wavelength 436 nm)). Furthermore, the evaluation of the light-shielding film pattern was performed in the same manner as in Example 1. As a result, the side surface of the light-shielding film pattern becomes a tapered shape near the transparent substrate and an inverted tapered shape near the resist film, resulting in a very poor cross-sectional shape. Furthermore, it was confirmed that the angle between JET and the transparent substrate is 150° when JET is 100%.

Next, using the photomask substrate of Comparative Example 1, a photomask was produced in the same manner as in Example 1. The CD uniformity of the light-shielding film pattern of the obtained mask was measured, and the result was poor, which was 200 nm. In this way, in the mask base of Comparative Example 1, the reflectivity of the front and back surfaces can be reduced, but a high-precision mask pattern cannot be formed.

As above, in the light-shielding film of the mask base, each of the first reflection-inhibiting layer, the light-shielding layer, and the second reflection-inhibiting layer is formed of a material with a specific composition, and the front and back sides of the light-shielding film are reflected respectively The film thickness of each layer is set in such a way that the rate is 10% or less and the optical density becomes 3.0 or more to form the mask base. By this, when the mask is produced by etching, a CD uniformity and high-precision mask can be obtained. Hood pattern. According to this type of photomask, a display device with less display unevenness can be manufactured.

1‧‧‧Mask base 11‧‧‧Transparent substrate 12‧‧‧Light-shielding film 13‧‧‧The first reflection suppression layer 14‧‧‧The light-shielding layer 15‧‧‧The second reflection suppression layer

Fig. 1 is a cross-sectional view showing a schematic configuration of a photomask substrate according to an embodiment of the present invention. FIG. 2 is a diagram showing the composition analysis result of the film thickness direction in the mask substrate of Example 1. FIG. FIG. 3 is a graph showing the reflectance spectrum of the front and back of the mask substrate of Example 1. FIG. 4 is a diagram for explaining the characteristics of the cross-sectional shape of the light-shielding film pattern of the photomask fabricated using the photomask substrate of Example 1. FIG. FIG. 5 is a schematic diagram for explaining the film forming mode when the light shielding film is formed by reactive sputtering.

1‧‧‧Mask base

11‧‧‧Transparent substrate

12‧‧‧Shading film

13‧‧‧The first reflection suppression layer

14‧‧‧Shading layer

15‧‧‧Second reflection suppression layer

Claims (22)

A photomask base, which is characterized in that it is a photomask base used when manufacturing a display device manufacturing photomask, and has: a transparent substrate, which is composed of a material that is substantially transparent to exposure light; a light-shielding film, It is provided on the transparent substrate and is made of a material that is substantially opaque to the exposure light; the light-shielding film includes a first reflection suppression layer, a light-shielding layer, and a second reflection suppression layer from the transparent substrate side, the The first reflection suppression layer is a chromium-based material containing chromium, oxygen and nitrogen, and has a chromium content of 25 to 75 atomic %, an oxygen content of 15 to 45 atomic %, and a nitrogen content of 10 to 30 atoms %, the light-shielding layer is composed of a chromium-based material containing chromium and nitrogen, and the chromium content is 70 to 95 atomic %, and the nitrogen content is 5 to 30 atomic %. The second reflection suppression layer is composed of A chromium-based material containing chromium, oxygen and nitrogen, with a chromium content of 30 to 75 atomic %, an oxygen content of 20 to 50 atomic %, and a nitrogen content of 5 to 20 atomic% to make When the reflectance of the front and back surfaces of the light-shielding film with respect to the exposure wavelength of the exposure light is 10% or less, and the optical density becomes 3.0 or more, the first reflection suppression layer, the light-shielding layer, and the second The film thickness of the reflection suppression layer. The photomask substrate of claim 1, wherein the content of chromium of the first reflection suppression layer is 50 to 75 atomic %, the content of oxygen is 15 to 35 atomic %, and the content of nitrogen is 10 to 25 atomic %, The chromium content of the second reflection suppression layer is 50 to 75 atomic %, the oxygen content is 20 to 40 atomic %, and the nitrogen content is 5 to 20 atomic %. The photomask substrate of claim 1 or 2, wherein the first reflection suppression layer and the second reflection suppression layer respectively have a content of at least any one of oxygen and nitrogen along the film thickness direction continuously or stepwise The area where the composition has changed. The photomask substrate of claim 1 or 2, wherein the second reflection suppressing layer has a region where the oxygen content rate increases toward the side of the light shielding layer in the film thickness direction. The photomask substrate of claim 1 or 2, wherein the second reflection suppression layer has a region where the nitrogen content is reduced toward the side of the light shielding layer in the film thickness direction. The photomask substrate of claim 1 or 2, wherein the first reflection suppressing layer has a region where the transparent substrate faces the film thickness direction and the oxygen content rate increases and the nitrogen content rate decreases. The photomask substrate of claim 1 or 2, wherein the second reflection suppressing layer is formed in such a way that the content of oxygen becomes higher than that of the first reflection suppressing layer. The photomask substrate of claim 1 or 2, wherein the first reflection suppression layer is formed so that the nitrogen content is higher than that of the second reflection suppression layer. The mask substrate of claim 1 or 2, wherein the light-shielding layer includes chromium (Cr) and chromium nitride (Cr ₂ N). The mask substrate of claim 1 or 2, wherein the first reflection suppression layer and the second reflection suppression layer include chromium nitride (CrN), chromium (III) oxide (Cr ₂ O ₃ ), and chromium oxide (VI) (CrO ₃ ). Such as the photomask base of claim 1 or 2, wherein the above-mentioned transparent substrate is a rectangular substrate, and the length of the short side of the substrate is 850 mm or more and 1620 mm or less. The mask base of claim 1 or 2, wherein between the transparent substrate and the light-shielding film, there is further provided a semi-transmissive film having an optical density lower than that of the light-shielding film. The photomask base of claim 1 or 2, wherein a phase shift film is further provided between the transparent substrate and the light-shielding film. A method of manufacturing a photomask substrate, characterized in that it is a manufacturing method of a photomask substrate used when manufacturing a photomask for manufacturing a display device, and the photomask is made of a material that is substantially transparent to exposure light. A light-shielding film made of a material that is substantially opaque to exposure light is formed on the transparent substrate by sputtering, and has the following steps: On the transparent substrate, by using a sputtering target containing chromium, and Reactive sputtering containing a sputtering gas containing oxygen-based gas, nitrogen-based gas reactive gas and rare gas to form a first reflection suppression layer, the first reflection suppression layer is a chromium series containing chromium, oxygen and nitrogen The material has a composition with a chromium content of 25 to 75 atomic%, an oxygen content of 15 to 45 atomic%, and a nitrogen content of 10 to 30 atomic%; on the above-mentioned first reflection suppression layer, by using Reactive sputtering of a sputtering target containing chromium and a sputtering gas containing a reactive gas containing a nitrogen-based gas and a rare gas to form a light-shielding layer which is a chromium-based material containing chromium and nitrogen and has a chromium A composition with a content of 70 to 95 atomic% and a nitrogen content of 5 to 30 atomic %; and on the light shielding layer, by using a sputtering target containing chromium, and a composition containing oxygen-based gas and nitrogen-based gas The reactive sputtering of the sputtering gas of the reactive gas and the rare gas forms the second reflection suppression layer, which is a chromium-based material containing chromium, oxygen, and nitrogen, and has a chromium content ratio of 30 to 75 The composition is composed of atomic %, oxygen content of 20-50 atomic%, and nitrogen content of 5-20 atomic%; in the above reactive sputtering, the flow rate of the reactive gas contained in the sputtering gas is selected to be metal For the flow rate of the mode, the first reflection suppression layer and the light-shielding layer are formed so that the reflectivity of the front and back of the light-shielding film with respect to the exposure wavelength of the exposure light is 10% or less, and the optical density is 3.0 or more , And the film thickness of the above-mentioned second reflection suppression layer. The method for manufacturing a photomask substrate of claim 14, wherein the above-mentioned oxygen-based gas is oxygen (O ₂ ) gas. The method for manufacturing a photomask base according to claim 14 or 15, wherein the first reflection suppression layer, the light shielding layer, and the second reflection suppression layer use one side to move the transparent substrate relative to the sputtering target It is formed by an in-line sputtering device in which the above-mentioned light-shielding film is deposited on one side. The method for manufacturing a mask base according to claim 14 or 15, wherein between the transparent substrate and the light-shielding film, a semi-transmissive film having an optical density lower than that of the light-shielding film is formed. The method for manufacturing a photomask base according to claim 14 or 15, wherein a phase shift film is formed between the transparent substrate and the light-shielding film. A method for manufacturing a photomask, characterized by having the following steps: preparing the above-mentioned photomask substrate as claimed in any one of claims 1 to 11; and forming a resist film on the above-mentioned light-shielding film, and removing from the above-mentioned resist film The formed resist pattern is used as a mask to etch the light-shielding film to form a light-shielding film pattern on the transparent substrate. A method for manufacturing a photomask, characterized in that it has the following steps: preparing the above-mentioned photomask base as in claim 12; forming a resist film on the above-mentioned light-shielding film, and using the resist pattern formed from the above-mentioned resist film as A mask etches the light-shielding film to form a light-shielding film pattern on the transparent substrate; and uses the light-shielding film pattern as a mask to etch the translucent film to form a semi-light-transmitting film pattern on the transparent substrate. A method for manufacturing a photomask, characterized in that it has the following steps: preparing the above-mentioned photomask base as claimed in claim 13; forming a resist film on the above-mentioned light-shielding film, and using the resist pattern formed from the above-mentioned resist film as A mask etches the light-shielding film to form a light-shielding film pattern on the transparent substrate; and uses the light-shielding film pattern as a mask to etch the phase shift film to form a phase shift film pattern on the transparent substrate. A method of manufacturing a display device, characterized by having an exposure step, the exposure step is to place a mask obtained by the method of manufacturing a mask according to any one of claims 19 to 21 on the mask of the exposure device A stage for exposing and transferring at least one mask pattern of the light-shielding film pattern, the semi-transparent film pattern, and the phase shift film pattern formed on the photomask to the resist formed on the substrate of the display device.

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