TWI755337B - Photomask blank, method of manufacturing photomask, and method of manufacturing display device - Google Patents

Abstract

The present invention provides a mask substrate capable of obtaining a high-precision mask pattern when a mask is fabricated by etching, and satisfying optical characteristics such as suppressing uneven display when using the mask to fabricate a display device. The photomask substrate of the present invention is characterized in that it is a photomask substrate used in the production of photomasks used in the manufacture of display devices, and has: a transparent substrate composed of a material that is substantially transparent to exposure light; a light shielding film , which is arranged on a transparent substrate and is composed of a material that is substantially opaque to exposure light; the light-shielding film is provided with a first reflection suppressing layer, a light-shielding layer and a second reflection suppressing layer from the transparent substrate side, and the first reflection suppressing layer The layer is a chromium-based material containing chromium, oxygen and nitrogen, and has a composition of 25 to 75 atomic % of chromium, 15 to 45 atomic % of oxygen, and 10 to 30 atomic % of nitrogen. The light-shielding layer is a chromium-based material containing chromium and nitrogen, and has a composition of 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. A chromium-based material 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 %, so that the front and back surfaces of the light-shielding film are The film thicknesses of the first reflection suppressing layer, the light shielding layer, and the second reflection suppressing 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 becomes 3.0 or more.

Description

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

The present invention relates to a photomask substrate and a method for manufacturing the same, a method for manufacturing a photomask, and a method for manufacturing a display device.

In display devices such as FPD (Flat Panel Display) represented by LCD (Liquid Crystal Display, liquid crystal display), along with large screen and wide viewing angle, high-definition and high-speed display are rapidly developing. One of the elements required for such high-definition and high-speed display is the production of electronic circuit patterns such as fine and highly dimensionally accurate elements and wirings. The patterning of the electronic circuit for the display device mostly uses photolithography. Therefore, there is a need for a photomask for manufacturing a display device in which a fine and high-precision pattern is formed.

Photomasks used in the manufacture of display devices are fabricated from photomask substrates. The mask base is formed by disposing 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 mask base or the mask, in order to suppress the reflection of light during exposure, a reflection suppression layer is provided on the front and back sides of the light shielding film. The light-shielding layer and the second reflection suppressing layer are laminated. The mask is formed by patterning the light-shielding film of the mask base by wet etching and the like and forming a specific pattern. Made with mask pattern.

Patent Document 1 discloses a technology related to a photomask for manufacturing such a display device, a photomask substrate serving as its original, and a method for producing both.

[Prior Art Literature] [Patent Literature]

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

In the manufacture of display devices (such as display panels for TV (TeleVision, television)), for example, using a photomask, after transferring a specific pattern to a substrate for a display device, the substrate for a display device is slid to transfer the specific pattern. Here, pattern transfer is repeated. In this transfer, when the exposure light from the light source of the exposure device is incident on the photomask, the reflected light on the back side of the photomask, or the reflected light from the transfer object after the exposure light passes through the photomask returns to the front surface of the photomask. Due to the influence of the reflected light from the side, the exposure light as assumed above may be irradiated in the vicinity of the overlap of the display device. As a result, exposure may be performed so that adjacent patterns may partially overlap each other, and display unevenness may occur in the manufactured display device.

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

In addition, the photomask used in the manufacture of display devices is not only a high-definition display device, but also In addition to the requirements of high-speed display, the size of substrates tends to increase, and in recent years, ultra-large photomasks using rectangular substrates with a short side length of 850 mm or more have been used in the manufacture of display devices. Furthermore, as the above-mentioned large photomasks whose short side length is 850mm or more, there are 850mm×1200mm size for G7, 1220mm×1400mm size for G8, and 1620mm×1780mm size for G10, especially for such large photomasks. The CD uniformity (CD Uniformity) of the mask pattern requires a high-precision mask pattern below 100 nm.

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

An object of the present invention is to provide a mask substrate which can obtain a mask pattern with high precision when a mask is fabricated by etching, and satisfy the optical characteristics of suppressing display unevenness when using the mask to fabricate a display device.

(Constitution 1)

A photomask substrate is characterized in that: it is a photomask substrate used in the manufacture of photomasks used in the manufacture of display devices, 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 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 suppression layer from the transparent substrate side, 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 atomic %. The composition of atomic %, the above-mentioned light-shielding layer is a chromium-based material containing chromium and nitrogen, and has a composition of chromium content of 70 to 95 atomic % and nitrogen content of 5 to 30 atomic %, the second reflection suppression layer. It 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 first reflection suppressing layer, the light shielding layer, and the first reflection suppressing layer are set so 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, respectively, and the optical density is 3.0 or more. 2 The thickness of the reflection suppression layer.

(Constitution 2)

The photomask substrate of the configuration 1 is characterized in that the content of the first reflection suppressing layer is 50 to 75 atomic % of chromium, 15 to 35 atomic % of oxygen, and 10 to 25 atomic % of nitrogen. %, 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 %.

(Composition 3)

The photomask substrate of the configuration 1 or 2 is characterized in that the first reflection suppressing layer and the second reflection suppressing layer each have a content rate of at least one of oxygen and nitrogen that is continuous or stepwise along the film thickness direction. Areas where compositional changes occur.

(Composition 4)

The mask base of any one of the constitutions 1 to 3 is characterized in that the second reflection suppressing layer has a region in which the oxygen content increases toward the light shielding layer side in the film thickness direction.

(Constitution 5)

The mask base of any one of the constitutions 1 to 4 is characterized in that the second reflection suppressing layer has a region in which the nitrogen content decreases toward the light shielding layer side in the film thickness direction.

(Constitution 6)

The photomask base according to any one of the constitutions 1 to 5, wherein the first reflection suppressing layer has a region in which the oxygen content increases and the nitrogen content decreases toward the transparent substrate in the film thickness direction.

(Constitution 7)

According to the photomask substrate of any one of 1 to 6, the second reflection suppressing layer is configured such that the oxygen content is higher than that of the first reflection suppressing layer.

(Composition 8)

According to the photomask substrate of any one of 1 to 7, the first reflection suppressing layer is configured such that the nitrogen content is higher than that of the second reflection suppressing layer.

(Constitution 9)

According to the photomask substrate constituting any one of 1 to 8, the light shielding layer comprises chromium (Cr) and chromium nitride (Cr ₂ N).

(composition 10)

According to the photomask substrate of any one of constitutions 1 to 9, wherein the first reflection suppression layer and the second reflection suppression layer comprise chromium nitride (CrN), chromium (III) oxide (Cr ₂ O ₃ ) and chromium oxide (VI) (CrO3 ₎ .

(Composition 11)

According to any one of 1 to 10, the photomask substrate 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.

(composition 12)

The mask base of any one of 1 to 11 is characterized by further comprising a semi-transparent film having an optical density lower than that of the light-shielding film between the transparent substrate and the light-shielding film.

(composition 13)

The mask base of any one of the constitutions 1 to 11 is characterized in that a phase shift film is further provided between the transparent substrate and the light shielding film.

(composition 14)

A method for manufacturing a photomask substrate, characterized in that: it is a method for manufacturing a photomask substrate used in the manufacture of a photomask used in the manufacture of a display device, the photomask is substantially A light-shielding film composed of a material that is substantially opaque to exposure light is formed by sputtering on a transparent substrate composed of a transparent material, and has the following steps: on the above-mentioned transparent substrate, by using a material containing chromium The sputtering target, reactive sputtering with a reactive gas containing an oxygen-based gas, a nitrogen-based gas, and a sputtering gas containing a rare gas to form a first reflection-suppressing layer, the first reflection-suppressing layer containing chromium, A chromium-based material of oxygen and nitrogen having 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 %; in the above-mentioned first reflection suppression On the layer, a light-shielding layer is formed by reactive sputtering using a sputtering target containing chromium and a sputtering gas containing a reactive gas containing a nitrogen-based gas and a rare gas, and the light-shielding layer is a chromium-containing chromium and nitrogen It is a material and has a composition with a chromium content of 70 to 95 atomic % and a nitrogen content of 5 to 30 atomic %; and on the above-mentioned light shielding layer, by using a sputtering target containing chromium, and a Reactive sputtering of gas, reactive gas of nitrogen-based gas, and sputtering gas of rare gas to form a second reflection-suppressing layer, the second reflection-suppressing layer is a chromium-based material containing chromium, oxygen, and nitrogen and has chromium A composition with a content of 30 to 75 atomic %, an oxygen content of 20 to 50 atomic %, and a nitrogen content of 5 to 20 atomic %; in the above reactive sputtering, the reactive gas contained in the sputtering gas The flow rate is selected to be the flow rate of the metal mode, and the reflectance of the front and back surfaces of the light shielding film with respect to the exposure wavelength of the exposure light is respectively 10% or less, and the optical density is 3.0 or more to form the first reflection. The film thicknesses of the suppression layer, the light shielding layer, and the second reflection suppression layer.

(composition 15)

The manufacturing method of the photomask substrate according to the constitution 14 is characterized in that: the oxygen-based gas is oxygen (O ₂ ) gas.

(composition 16)

The method for producing a mask base of the configuration 14 or 15, wherein the first reflection suppressing layer, the light shielding layer, and the second reflection suppressing layer are formed by using one surface to make the transparent substrate relative to the sputtering target. It was formed by moving an in-line sputtering apparatus for forming the above-mentioned light-shielding film on one side.

(composition 17)

The method for manufacturing a mask base according to any one of the constitutions 14 to 16, wherein a semi-transparent film having an optical density lower than that of the light-shielding film is formed between the transparent substrate and the light-shielding film .

(composition 18)

The manufacturing method of the photomask base according to any one of the constitutions 14 to 16 is characterized in that a phase shift film is formed between the transparent substrate and the light shielding film.

(composition 19)

A method of manufacturing a photomask, comprising the steps of: preparing the above-mentioned photomask substrate as constituted in any one of 1 to 11; and forming a resist film on the above-mentioned light-shielding film, and forming a resist film The resist pattern 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, comprising the steps of: preparing the above-mentioned photomask substrate as constituted in 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 shield The 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 semi-transparent film to form a semi-transparent film pattern on the transparent substrate.

(composition 21)

A method for manufacturing a photomask, comprising the steps of: preparing the above-mentioned photomask substrate as constituted in 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 shield The 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.

(composition 22)

A method of manufacturing a display device, which is characterized by having an exposure step of placing a mask obtained by the method of manufacturing a mask of any one of constitutions 19 to 21 on a mask carrier of an exposure device a stage for exposing and transferring at least one mask pattern of the above-mentioned light-shielding film pattern, the above-mentioned semi-transparent film pattern, and the above-mentioned phase shift film pattern formed on the above-mentioned photomask to the mask pattern formed on the display The resist on the device substrate is shown.

According to the present invention, a photomask substrate capable of producing a photomask excellent in pattern accuracy and having optical characteristics capable of suppressing display unevenness as in the manufacture of a display device is obtained.

1: Photomask base

11: Transparent substrate

12: shading film

13: 1st reflection suppression layer

14: shading layer

15: 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 results of composition analysis in the film thickness direction in the photomask substrate of Example 1. FIG.

FIG. 3 is a graph showing the reflectance spectra of the front and back surfaces of the mask substrate of Example 1. FIG.

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 view for explaining a film-forming mode when a light-shielding film is formed by reactive sputtering.

Hereinafter, 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 code|symbol is attached|subjected to the same or equivalent part in a figure, and the description may be simplified or abbreviate|omitted.

<Reticle Base>

A photomask base according to an embodiment of the present invention will be described. The photomask substrate of the present embodiment is produced by exposing a single wavelength of light selected from a wavelength region of 300 nm to 550 nm, or by exposing light including a plurality of wavelengths (for example, j-ray (wavelength: 313 nm), i-ray (wavelength: 365 nm) nm), h-ray (405nm), g-ray (wavelength 436nm)) compound light exposure for display device manufacturing mask used. In addition, the numerical range represented using "~" in this specification means the range which includes the numerical value described before and after "~" as a lower limit value and an upper limit value.

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 includes a transparent substrate 11 and a light shielding film 12 . Hereinafter, as a photomask substrate according to an embodiment of the present invention, a photomask substrate of a binary type in which the mask pattern (transfer pattern) of the photomask 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 is not particularly limited as long as it is a substrate having translucency. A substrate material with a transmittance of 85% or more, preferably 90% or more, relative to the exposure wavelength is used. As a material for forming the transparent substrate 11 , for example, synthetic quartz glass, soda lime glass, alkali-free glass, and low thermal expansion glass can be mentioned.

The size of the transparent substrate 11 can be appropriately changed according to the size required for the photomask used in the manufacture of the display device. For example, as the transparent substrate 11 , a rectangular substrate can be used, and the length of the short side thereof 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 mm, 850 mm×1400 mm, 1220 mm×1400 mm, 1620 mm×1780 mm can be used and other substrates. In particular, the length of the short side of the substrate is preferably 850 mm or more and 1620 mm or less. By using such a transparent substrate 11, the photomasks for display device manufacture of G7-G10 are obtained.

(shading film)

The light-shielding film 12 is configured by laminating the first reflection suppression layer 13 , the light-shielding layer 14 , and the second reflection suppression layer 15 in this order from the transparent substrate 11 side. 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 suppressing layer 13 is provided in the light-shielding film 12 on the surface of the light-shielding layer 14 on the side close to the transparent substrate 11 . When pattern transfer is performed using a photomask made from the photomask base 1 , it is disposed on the Close to the side of the exposure light source. In the case of exposure treatment using a photomask, exposure light is irradiated from the transparent substrate 11 side (back surface side) of the photomask to transfer the pattern transfer image to the resist formed on the substrate for a display device as the transfer target body. Etch film. At this time, if the exposure light is reflected from the back side of the light-shielding film pattern, it may become stray light of the masking pattern as the light-shielding film pattern, resulting in the formation of a ghost image, an increase in the amount of glare, and other deterioration of the transferred image, or In the vicinity of the overlap of the substrates for display devices, the exposure light above the assumption was irradiated, resulting in uneven display. The first reflection suppressing 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 mask, thereby suppressing deterioration of the transfer image and contributing to the improvement of transfer characteristics, and In the vicinity of the overlap of the substrates for display devices, the occurrence of display unevenness due to exposure to the exposure light above the assumption can be suppressed.

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

The second reflection suppressing layer 15 is provided in the light shielding film 12 on the surface of the light shielding layer 14 on the side away from the transparent substrate 11 . The second reflection suppressing layer 15 is formed by forming a resist film thereon and When a specific pattern is drawn on the resist film by drawing light (laser light) of a drawing device (eg, a laser drawing device), the reflection on the front side of the light shielding film 12 can be suppressed, so that the resist pattern and the CD uniformity of the formed mask pattern. In addition, when the second reflection suppressing layer 15 is used as a photomask, it is arranged on the substrate side of the display device as the transfer target body, and can suppress the light reflected by the transfer target body from passing through the front surface of the light shielding film 12 of the photomask. The side is reflected again and returned to the object to be transferred, and the deterioration of the transfer image is suppressed, which contributes to the improvement of the transfer characteristics, and the display by the exposure light above the assumption can be suppressed in the vicinity of the overlap of the display device substrate. Inequity arises.

(Material of shading film)

Next, the material of each layer in the light shielding film 12 will be described.

The first reflection suppressing layer 13 is formed of a chromium-based material containing chromium, oxygen, and nitrogen. Oxygen in the first reflection suppressing layer 13 has the effect of reducing the reflectance of exposure light from the back surface side. In addition, nitrogen in the first reflection suppressing layer 13 has the effect of reducing the reflectance of exposure light from the back side and also has the effect of making the light-shielding film pattern formed by etching (especially wet etching) using the mask base. The cross section is nearly 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 formed of a chromium-based material containing chromium and nitrogen. Nitrogen in the light-shielding layer 14 has the following effects to reduce the etching rate difference with the first reflection suppression layer 13 and the second reflection suppression layer 15 and to make the light-shielding layer formed by etching (especially wet etching) using a mask base. The cross section of the film pattern is close to vertical, and the etching time in the light shielding film 12 (the whole) 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 formed of a chromium-based material containing chromium, oxygen, and nitrogen. 2nd reflection Oxygen in the suppression layer 15 has the effect of reducing the reflectance of drawing light from the drawing device on the front side or the reflectivity of exposure light from the front side. In addition, the adhesion to the resist film is improved, and the effect of suppressing side etching due to permeation of the etchant from the interface between the resist film and the light shielding film 12 is exhibited. In addition, the nitrogen in the second reflection suppressing layer 15 has the effect of reducing the reflectance of the drawing light from the front side and the reflectivity of the exposure light from the front side, and also has the effect of reducing the reflectivity 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 CD uniformity is improved. Furthermore, from the viewpoint of controlling the etching characteristics, carbon or fluorine may be further contained.

(Composition of shading film)

Next, the composition of each layer in the light shielding film 12 will be described. In addition, the content rate of each element mentioned below was made into the value measured by X-ray photoelectron spectroscopy (XPS).

The light shielding film 12 is constituted so that the first reflection suppressing layer 13 contains 25 to 75 atomic % of chromium (Cr), 15 to 45 atomic % of oxygen (O), and 10 to 30 atomic %, respectively, 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), respectively, and the second reflection suppression layer 15 contains 30 to 30 atomic % of nitrogen (N). ~75 atomic % of chromium (Cr), 20 to 50 atomic % of oxygen (O), 5 to 20 atomic % of nitrogen (N). Preferably, the first reflection suppression layer 13 contains 50 to 75 atomic % of Cr, 15 to 35 atomic % of O, and 10 to 25 atomic % of N, respectively, and the second reflection suppression layer 15 is based on content. They contain 50 to 75 atomic % of Cr, 20 to 40 atomic % of O, and 5 to 20 atomic % of N.

Preferably, each of the first reflection suppression layer 13 and the second reflection suppression layer 15 has a region in which the content of at least one element of O and N changes continuously or in stages along the film thickness direction.

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

Moreover, it is preferable that the 2nd reflection suppression layer 15 has the area|region in which the N content rate (nitrogen content rate) falls toward the light shielding layer 14 side of a film thickness direction.

Moreover, it is preferable that the 1st reflection suppression layer 13 has the area|region in which the O content rate increases and the N content rate decreases toward the transparent substrate 11 in the film thickness direction.

Moreover, in the photomask substrate 1 and the photomask produced therefrom, it is preferable from the viewpoint of further reducing the reflectance of the front and back surfaces of the light shielding film 12 or the light shielding film pattern and making the difference between the reflectances smaller. In order to configure the second reflection suppressing layer 15 so that the O content rate is higher than that of the first reflection suppressing layer 13, it is preferable that the N content rate of the first reflection suppressing layer 13 be higher than that of the second reflection suppressing layer 15. The way to become taller. Specifically, the O content of the second reflection suppression layer 15 is preferably increased by 5 atomic % or more, more preferably 10 atomic % or more, than the first reflection suppression layer 13 . Furthermore, the N content of the first reflection suppression layer 13 is preferably increased by 5 atomic % or more, more preferably 10 atomic % or more, than the second reflection suppression layer 15 . In addition, when the 1st reflection suppression layer 13 or the 2nd reflection suppression layer 15 has a composition gradient area|region, the O content rate or N content rate shows the average density|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 of the content ratio of each element may be continuous or stepwise, but it is preferably continuous.

(About the bonding state (chemical state))

Preferably, the light shielding layer 14 includes 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 ).

(About film thickness)

In the light shielding film 12 , the thicknesses of the first reflection suppressing layer 13 , the light shielding layer 14 and the second reflection suppressing layer 15 are not particularly limited, and can be appropriately adjusted according to the optical density and reflectivity required by the light shielding film 12 . The thickness of the first reflection suppressing layer 13 only needs to be such that, with respect to light from the back side of the light shielding film 12 , reflection from the front surface of the first reflection suppressing layer 13 and reflection at the interface between the first reflection suppressing layer 13 and the light shielding layer 14 are exhibited. The thickness of the resulting light interference effect is sufficient. On the other hand, the thickness of the second reflection suppressing layer 15 should be such that, with respect to the light from the front side of the light shielding film 12 , the reflection from the front surface of the second reflection suppressing layer 15 and the second reflection suppressing layer 15 and the light shielding layer 14 are exhibited. The thickness of the light interference effect caused by the reflection of the interface is sufficient. The thickness of the light-shielding layer 14 should just be a thickness such that the optical density of the light-shielding film 12 becomes 3 or more. Specifically, in the light-shielding film 12, the reflectance of the front and back surfaces with respect to the exposure wavelength is 10% or less, and the optical density is set to 3.0 or more, for example, the film of the first reflection suppression layer 13 can be 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 suppressing layer 15 is 10 nm to 60 nm.

<Manufacturing method of mask substrate>

Next, the manufacturing method of the said mask base 1 is demonstrated.

(preparatory steps)

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

(Step of Forming the First Reflection Suppression Layer)

Next, the first reflection suppression layer 13 is formed on the transparent substrate 11 . This formation is performed by reactive sputtering using a sputtering target containing Cr, a reactive gas containing an oxygen-based gas, a nitrogen-based gas, and a sputtering gas containing a rare gas. At this time, as the film formation conditions, 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 metallic mode will be described using FIG. 5 . 5 is a schematic diagram for explaining a film formation mode when a thin film is formed 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, the vertical axis 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 the film formation rate changes accordingly. There are three modes according to the difference in the film-forming speed. Specifically, as shown in FIG. 5 , there are a reaction mode in which the supply amount (ratio) of the reactive gas is made larger than a certain threshold value, a metal mode in which the supply amount (ratio) of the reactive gas is made smaller than the reaction mode, and The supply amount (ratio) of the gas 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 rate can be increased. Furthermore, in the metal mode, since the supply amount of the reactive gas is small, for example, a film having a more stoichiometric composition can be formed with at least one of the O concentration (oxygen concentration) or the N concentration (nitrogen concentration). membranes with lower concentrations. That is, a film with relatively high Cr content and low O content or N content can be formed.

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

As a sputtering target, what is necessary is just to contain Cr, for example, chromium-based materials such as chromium oxide, chromium nitride, and chromium oxynitride can be used in addition to chromium metal. 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, it is preferable to use oxygen (O ₂ ) gas when the oxidizing power is high. Moreover, nitrogen ( _N2 ) etc. can be used as a nitrogen-type gas. As the rare gas, for example, helium gas, neon gas, argon gas, krypton gas, xenon gas, or the like can be used. In addition to the above-mentioned reactive gas, a hydrocarbon-based gas may be supplied, and for example, methane gas, butane gas, or the like can be used.

In this embodiment, the flow rate of the reactive gas and the electric power applied to the sputtering target are set to the conditions of becoming a metal mode, and a sputtering target containing Cr is used to perform a film formation process by reactive sputtering, thereby, On the transparent substrate 11, the 1st reflection suppression layer 13 containing 25-75 atomic% of Cr, 15-45 atomic% of O, and 10-30 atomic% of N is formed.

Furthermore, when the first reflection suppressing 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, but in the film thickness direction When the composition inclination occurs due to the change of the above O content rate or N content rate, 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. Moreover, the arrangement|positioning of a gas supply port, a gas supply method, etc. may be changed.

(Step of forming the light shielding layer)

Next, the light shielding layer 14 is formed on the first reflection suppressing layer 13 . This formation is performed by reactive sputtering using a sputtering target contained therein and a sputtering gas containing a nitrogen-based gas and a rare gas. At this time, as the film formation conditions, the flow rate of the reactive gas contained in the sputtering gas is selected. Become the flow of metal patterns.

As a target, what is necessary is just to contain, for example, chromium-based materials such as chromium oxide, chromium nitride, and chromium oxynitride can be used in addition to chromium metal. As the nitrogen-based gas, nitrogen (N ₂ ) or the like can be used. As the rare gas, for example, helium gas, neon gas, argon gas, krypton gas, xenon gas, or the like can be used. In addition to the above-mentioned reactive gas, the oxygen-based gas and the hydrocarbon-based gas described above may be supplied.

In the present embodiment, the flow rate of the reactive gas and the power applied to the sputtering target are set to the conditions of the metallic mode, and reactive sputtering is performed using the contained sputtering target, whereby the first reflection suppressing layer 13 is formed. On the above, the light-shielding layer 14 containing 70 to 95 atomic % of Cr and 5 to 30 atomic % of N is formed.

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

(Step of forming the second reflection suppressing layer)

Next, the second reflection suppression layer 15 is formed on the light shielding layer 14 . This formation is performed by reactive sputtering using the contained sputtering target by setting the flow rate of the reactive gas and the target applied electric power to the conditions as in the metallic mode as in the case of the first reflection suppressing layer 13 . Thereby, on the light shielding layer 14, the 2nd reflection suppression layer 15 containing 30-75 atomic% of Cr, 20-50 atomic% of O, and 5-20 atomic% of N is formed.

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

Furthermore, when the composition of the second reflection suppressing layer is inclined, the type and 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 as described above.

From the above, the mask substrate 1 of the present embodiment is obtained.

In addition, the film formation of each layer in the light-shielding film 12 can be performed by in-situ using an in-line sputtering apparatus. In the case of a non-inline sputtering device, the transparent substrate 11 must be taken out of the device after film formation of each layer, and the transparent substrate 11 must be exposed to the atmosphere, and each layer is surface oxidized or surface carbonized. As a result, the reflectance or etching rate of the light shielding film 12 with respect to exposure light may be changed. Therefore, in the in-line sputtering apparatus, the transparent substrate 11 is not taken out of the apparatus to be exposed to the atmosphere, and each layer can be continuously formed, thereby suppressing the incorporation of unintended elements into the light shielding film 12 .

Furthermore, when the light-shielding film 12 is formed using an in-line sputtering apparatus, the first reflection suppressing layer 13, the light-shielding layer 14, and the second reflection suppressing layer 15 have a composition gradient that continuously generates composition gradients among the layers. Therefore, the cross-section of the light-shielding film pattern formed by etching (especially wet etching) using the mask substrate is smooth and can be close to vertical, so it is preferable.

<Manufacturing method of photomask>

Next, a method of manufacturing a photomask using the above-described photomask substrate 1 will be described.

(Formation step of resist film)

First, a resist is coated on the second reflection suppressing layer 15 in the light shielding film 12 of the mask substrate 1, and a resist film is formed after drying. As a resist, it must be selected according to the drawing device used Positive or negative resists can be used as appropriate.

(Step of forming resist pattern)

Next, a specific pattern is drawn on the resist film using a drawing device. Generally, a laser drawing device is used in the production of a photomask for the manufacture of a display device. After drawing, a specific resist pattern is formed by developing and rinsing the resist film.

In this embodiment, since the reflectance of the 2nd reflection suppression layer 15 is comprised so that the reflectance may become low, when drawing a pattern on a resist film, the reflection of drawing light (laser light) can be reduced. Thereby, a resist pattern with high pattern precision can be formed, and subsequently, a mask pattern with high dimensional precision can be formed.

(Step of forming mask pattern)

Then, by etching the light-shielding film 12 using the resist pattern as a mask, a mask pattern composed of the light-shielding film pattern is formed. The etching can be either wet etching or dry etching. Usually, wet etching is performed in a photomask for manufacturing a display device, and as an etching solution (etchant) used in the wet etching, for example, a chromium etching solution containing ceric ammonium nitrate and perchloric acid can be used.

In this embodiment, in the thickness direction of the light shielding film 12, the composition of each layer is adjusted so that the etching rates of the first reflection suppressing layer 13, the light shielding layer 14, and the second reflection suppressing layer 15 are equalized, so that wet etching can be performed. The cross-sectional shape after that, that is, the cross-sectional shape of the light-shielding film pattern (mask pattern) is close to vertical with respect to the transparent substrate 11, so that higher 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.

From the above, the mask of the present embodiment is obtained.

<Manufacturing method of display device>

Next, a method of manufacturing a display device using the above-mentioned photomask will be described.

(preparatory steps)

First, a photomask obtained by the above-described photomask manufacturing method is formed with a projection optical system of an intervening exposure device with respect to a substrate with a resist film in which a resist film is formed on a substrate of a display device. The resist film on the substrate is placed on the mask stage of the exposure device in an arrangement in which the resist films face 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.

For example, the exposure light uses single-wavelength light (j-ray (wavelength 313nm), i-ray (wavelength 365nm), h-ray (wavelength 405nm), g-ray (wavelength 436nm), etc.) selected from the wavelength range of 300nm to 550nm), or contains Light of multiple wavelengths (eg, j-ray (wavelength 313nm), i-ray (wavelength 365nm), h-ray (405nm), g-ray (wavelength 436nm)) composite light. In this embodiment, since a display device (display panel) is manufactured using a mask whose reflectivity of the front and back of the light-shielding film pattern (mask pattern) is reduced, a display device (display panel) without display unevenness can be obtained.

<Effects of the present embodiment>

According to this embodiment, one or a plurality of effects shown below are exhibited.

(a) The mask base 1 of the present embodiment is constructed by laminating the first reflection suppressing layer 13 , the light shielding layer 14 , and the second reflection suppressing layer 15 to form the light shielding film 12 , and the first reflection suppressing layer 13 It is a chromium-based material containing chromium, oxygen and nitrogen, and has 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 %. A chromium-based material containing chromium and nitrogen, and having 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 Cr content of 30 to 75 atomic %, an O content of 20 to 50 atomic %, and a N content of 5 to 20 atomic %. Furthermore, the thicknesses of the first reflection suppressing layer 13 and the second reflection suppressing layer 15 are set to be the thicknesses at which the light interference effect is obtained at the maximum or near the maximum. Thereby, the reflectance of the front and back surfaces of the mask substrate 1 with respect to the exposure wavelength can be lowered to be 10% or less, respectively. Specifically, in the reflectance spectrum of the front and back, the wavelength of the bottom peak with extremely small reflectance can be set to 380nm~480nm on the relatively high wavelength side, and the reflectance of light with a wavelength of 380nm~480nm can be set to 10% or less, preferably 7.5% or less. On the other hand, by setting the light-shielding layer 14 to have a specific thickness, the optical density in the light-shielding film 12 can be made 3.0 or more.

(b) Further, in this embodiment, by appropriately changing the compositions of the first reflection suppressing layer 13 and the second reflection suppressing layer 15 within the above-mentioned ranges, the rear side of the mask base 1 (the transparent substrate 11 The reflectance on the side) and the reflectance on the front side (the light shielding film 12 side). For example, the reflectivity 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 exposing the transferred body using the prepared photomask, the self-suppression of the exposure light from the photomask to the light source side From the viewpoint of the influence by reflection (the occurrence of ghost images, etc.), it is preferable to make the reflectance of the back side higher than that of the front side. In other words, it is preferable that the reflectance on the front side (the light shielding film 12 side) of the mask base 1 is lower than the reflectance on the back side (the transparent substrate 11 side). Specifically, the gate electrode or the wiring pattern of the source electrode/drain electrode in the TFT (thin-film transistor) array is transferred to the substrate of the display device formed as the transferred body When the resist film is used, the aperture ratio of the light-shielding film pattern of the photomask becomes 50% or more, so the exposure light amount passing through the photomask increases, so glare is easily generated due to the return light of the exposure light from the transfer object side. Therefore, by making the reflectance of the front side and the back side of the light shielding film 12 of the mask substrate 1 respectively 10% or less with respect to the exposure wavelength, and making the reflectivity of the front side of the light shielding film 12 lower than the reflectivity of the back side, It can reduce the effect of glare and prevent CD errors when using photomasks to make display devices.

(c) In addition, in this embodiment, by making the layers of the first reflection suppressing layer 13, the light shielding layer 14, and the second reflection suppressing layer 15 constituting the light shielding film 12 within the above-mentioned composition range, the reduction in 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 light-shielding film 12 of the mask base 1 , that is, the cross-sectional shape of the mask pattern can be made to be nearly vertical with respect 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 within a 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 of the first reflection suppression layer 13 and the second reflection suppression layer 15 (so-called undercut), side Etching etc. As a result, the CD uniformity in the mask pattern (light-shielding film pattern) can be improved, and a mask pattern with a high precision of 100 nm or less can be formed.

(d) In addition, in the present embodiment, the light-shielding film 12 is formed by making the etching rates of the first reflection suppressing layer 13, the light-shielding layer 14, and the second reflection suppressing layer 15 constituting the light-shielding film 12 the same regardless of the etching rate. The length of time, the thickness of the etching solution, and the temperature of the etching solution can be used. The verticality of the cross-sectional shape is stably ensured. For example, when the exact etching time of the light shielding film 12 is set to T, even when the etching time is set to 1.5×T and 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 overetching with the etching time of 1.5×T can be 10° or less. . Similarly, when the concentration of the etching solution is increased and the concentration of the etching solution is decreased, the difference in the angle formed by the cross section of the light-shielding film pattern may 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, the room temperature is 23° C.), the higher the temperature of the etching solution, the faster the etching rate. Although it is high, the difference of the angle formed by the cross section of a light-shielding film pattern can be made into 10 degrees or less. In addition, the "just etching time" means 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 suppressing layer 13 and the second reflection suppressing layer 15 are made of a chromium-based material containing chromium, oxygen and nitrogen, and the first reflection suppressing layer 13 respectively contains 50 to 75 atomic % of Cr, 15 to 35 atomic % of O, 10 to 25 atomic % of N, and the second reflection suppression layer 15 contains 50 to 75 atomic % of Cr and 20 to 40 atomic % of Cr, respectively. 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, an excessive increase in the etching rate due to O in the layers containing these can be suppressed. Therefore, in order to make the etching rates of the first reflection suppressing layer 13, the light shielding layer 14, and the second reflection suppressing layer 15 constituting the light shielding film 12 uniform, the content rate of carbon (C) 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 content rate of Cr 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 By further reducing the N content rate, an excessive increase in the etching rate due to N in the layer containing these can be suppressed. Therefore, the N content in the light-shielding layer 14 can be reduced for the purpose of making the etching rates of the first reflection suppressing layer 13 , the light-shielding layer 14 , and the second reflection-suppressing layer 15 of the light-shielding film 12 uniform. As a result, the content rate of Cr in the light shielding layer 14 can be increased, and the optical density (OD) can be maintained high.

(f) Preferably, the first reflection suppressing layer 13 and the second reflection suppressing layer 15 each have a region in which the content of at least one of O and N changes in composition continuously or in stages along the film thickness direction. By changing the composition of each layer of the first reflection suppressing layer 13 and the second reflection suppressing layer 15, O or N in each layer can be locally introduced into a region where the content of O or N is high in each layer, while O or N in each layer can be changed. The average content rate was kept low. Thereby, the reflectivity of the front side and the back side of the photomask substrate 1 can be kept low.

In addition, in each of the first reflection suppressing layer 13 , the light shielding layer 14 , and the second reflection suppressing layer 15 constituting the light shielding film 12 , if the O content becomes high, the etching rate increases excessively, or if the N content increases, the etching rate increases excessively. When the etching rate is excessively increased, the difference in the etching rate of each layer due to the inclusion of these elements can be suppressed by reducing the content rate of O or N. That is, the deviation of the etching rate between the 1st reflection suppression layer 13, the 2nd reflection suppression layer 15, and the light shielding layer 14 can be suppressed. As a result, in order to make the etching rates of the first reflection suppressing layer 13, the light shielding layer 14, and the second reflection suppressing layer 15 constituting the light shielding film 12 uniform, the amount of N or carbon contained in the light shielding layer 14 can be reduced, or the amount of carbon contained in the light shielding layer 14 can be reduced. The light shielding layer 14 does not contain carbon but does not contain carbon. As a result, the content rate of Cr in the light shielding layer 14 can be increased, and the optical density (OD) can be maintained high.

(g) It is preferable that the 2nd reflection suppression layer 15 has the area|region in which the O content rate increases toward the light shielding layer 14 side of a film thickness direction. As a result, in the second reflection suppressing 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 increased. Low. As a result, a desired reflectance can be obtained on the front side of the light shielding film 12 (the second reflection suppressing layer 15 ), and erosion due to excessive etching of the interface can be suppressed.

(h) It is preferable that the second reflection suppressing 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 2nd reflection suppression layer 15, the average N content rate in the film thickness direction is maintained to some extent, and the N content rate of the interface part with the light shielding layer 14 is locally reduced. As a result, erosion due to excessive etching at the interface between the second reflection suppressing layer 15 and the light shielding layer 14 can be suppressed.

(i) Preferably, the first reflection suppressing layer 13 has a region in which the O content increases and the N content decreases toward the transparent substrate 11 in the film thickness direction. In the first reflection suppressing layer 13 , by increasing the O content and decreasing the N content toward the transparent substrate 11 in the film thickness direction, the etching rate can be gradually decreased toward the transparent substrate 11 . Thereby, 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, the O content of the second reflection suppressing layer 15 is preferably greater than that of the first reflection suppressing layer 13 by 5 atomic % or more, and more preferably 10 atomic % or more. Moreover, the 1st reflection suppression layer 13 is comprised so that N content may become high compared with the 2nd reflection suppression layer 15. FIG. Specifically, the N content of the first reflection suppressing layer 13 is preferably greater than that of the second reflection suppressing layer 15 by 5 atomic % or more, and more preferably 10 atomic % or more. According to the investigations of the present 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 of the front side tends to be higher than that of the back side. . Therefore, the composition ratio (O content ratio, N content ratio) 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 15 were The composition ratios (O content, N content) of the layer 15 are as described above, so that the reflectance on the back side can be adjusted to The front side is the same or 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) Further, according to the present embodiment, it is preferable that the light-shielding layer 14 is made of a chromium-based material including a bond state (chemical state) of chromium (Cr) and dichromium nitride (Cr ₂ N). By making the light-shielding layer 14 a chromium-based material containing a bond 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 light-shielding film pattern can be obtained. The cross-sectional shape is nearly vertical.

(1) Further, according to the present embodiment, it is preferable that the first reflection suppressing layer 13 and the second reflection suppressing layer 15 are made of chromium nitride (CrN), chromium (III) oxide (Cr ₂ O ₃ ) and oxide A chromium-based material in the bond state (chemical state) of chromium (VI) (CrO ₃ ). By making the first reflection suppression layer 13 and the second reflection suppression layer 15 contain a plurality of 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 chromium nitride of CrN, the excessive reduction of the etching rate due to the chromium oxide can be suppressed, so that the cross-sectional shape of the light-shielding film pattern can be made close to vertical. .

(m) Furthermore, according to the present embodiment, the first reflection suppression layer 13 and the second reflection suppression layer 15 are formed by using a sputtering target containing Cr and a sputtering gas containing an oxygen-based gas, a nitrogen-based gas, and a rare gas. A film is formed by reactive sputtering, 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. Furthermore, as the film-forming conditions of 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. This makes it easy to adjust the layers of the first reflection suppressing layer 13 , the light shielding layer 14 , and the second reflection suppressing layer 15 constituting the light shielding film 12 to the above-mentioned 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 the light-shielding film 12 is patterned can be close to vertical.

(n) When each layer of the first reflection suppression layer 13 and the second reflection suppression layer 15 is formed by reactive sputtering, it is preferable to use oxygen (O ₂ gas) as the oxygen-based gas. According to O ₂ gas, since the oxidizing power is higher than that of other oxygen-based gases, even when metal mode film formation is selected, each layer can be adjusted to the above-mentioned composition range more reliably. 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 mask substrate 1 of the present embodiment, since the reflectivity of the front side is low, a resist film is provided on the light shielding film 12, and a resist pattern is formed by drawing and developing steps, which can The reflection of the front surface of the light shielding film 12 for drawing light is reduced. Thereby, the dimensional accuracy of the resist pattern can be improved, and the dimensional accuracy of the light shielding film pattern of the photomask to be formed thereafter can be improved.

(p) Since the photomask manufactured from the photomask substrate 1 of the present embodiment has a high-precision light-shielding film pattern, and the reflectivity of the front and back surfaces of the light-shielding film pattern is lowered, when the pattern is transferred to the transfer target body, the Higher transfer characteristics.

(q) In the present 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 to increase the size of the mask base 1, the film thickness is The light-shielding film 12 is formed in such a manner that the etching rates of the directions are uniform, so that the CD uniformity of the mask pattern obtained by etching the light-shielding film 12 can be maintained high.

(r) In addition, since 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, the reflectance is 10% or less, preferably 7.5% or less, Further, it is preferably 5% or less, so that even when the exposure light intensity is increased by exposing the compound light including i-rays, h-rays and g-rays, for example, it is possible to form a higher level for the transfer object. The precision transfer pattern. Furthermore, in the vicinity of the overlap of the transfer target body (for example, a display panel), it is possible to prevent display from being irradiated with the exposure light above the assumption. uneven. Furthermore, as exposure light, there are composite light including light with a plurality of wavelengths selected from the wavelength region of 300nm to 550nm, or monochromatic light selected by cutting a wavelength region from the wavelength region of 300nm to 550nm using a filter or the like. For example, there is a composite light including j-rays with a wavelength of 313 nm, i-rays with a wavelength of 365 nm, h-rays with a wavelength of 405 nm, and g-rays with a wavelength of 436 nm, or monochromatic light of i-rays.

<Other Embodiments>

As mentioned above, although one Embodiment of this invention was demonstrated concretely, this invention is not limited to the said embodiment, It can change suitably in the range which does not deviate from the summary.

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, a semi-transparent film with a lower optical density than the light-shielding film 12 may be provided as a mask base between the transparent substrate and the light-shielding film 12 . The photomask substrate can be used as a photomask substrate for a gray-tone mask or a tone mask with the effect of reducing the number of photomasks to be used in the manufacture of display devices. The mask pattern in the gray-tone mask or the tone mask becomes a semi-transparent film pattern and/or a light-shielding film pattern.

In addition, instead of the semi-transparent film, a phase shift film for shifting the phase of the 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 the effect of higher pattern resolution due to the phase shift effect. The mask pattern in the phase shift mask becomes the phase shift film pattern, or the phase shift film pattern and the light shielding film pattern.

As the above-mentioned semi-transparent film and phase shift film, materials having etching selectivity with respect to the chromium-based material constituting the light-shielding film 12 are used. As such a material, a metal silicide-based material containing molybdenum (Mo), zirconium (Zr), titanium (Ti), tantalum (Ta), and silicon (Si) can be used, and a metal silicide-based material containing oxygen, A material of at least any one of nitrogen, carbon, or fluorine. For example, using MoSi, ZrSi, TiSi, TaSi and other metal silicides, oxides of metal silicides, nitrides of metal silicides, oxynitrides of metal silicides, carbonitrides of metal silicides, carbon of metal silicides Oxides, carbonized oxynitrides of metal silicides. In addition, these semitransparent films or phase shift films may be a laminate film composed of the above-mentioned films exemplified as functional films.

The transmittance of the above-mentioned semi-transparent film and 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 above-mentioned semi-transparent film and the phase shift film with respect to the exposure wavelength of the exposure light is preferably 20-80%. By selecting a semi-transparent film and a phase shift film with a transmittance of 20-80% relative to the exposure wavelength of the exposure light, and combining the light-shielding film of the present invention, a laminate of the semi-transparent film and the light-shielding film can be formed. The reflectance 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 with respect to the exposure wavelength.

In addition, in the said embodiment, the case where the 1st reflection suppression layer 13 and the 2nd reflection suppression layer 15 are each one layer was demonstrated, but this invention is not limited to this. For example, each layer may be a plurality of two or more layers.

In addition, in the above-described embodiment, an etching mask film composed of a material having an etching selectivity with respect to the light-shielding film 12 may be formed on the light-shielding film 12 .

Furthermore, in the above-described embodiment, an etching stopper film composed of a material having etching selectivity with respect to the light-shielding film may be formed between the transparent substrate 11 and the light-shielding film 12 . The above-mentioned etching mask film and etching stopper film are formed of materials having etching selectivity with respect to the 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, Si _3N4 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 mask base)

In this example, an in-line sputtering apparatus was used to manufacture the first reflection suppressing layer and the light shielding layer on a transparent substrate with a substrate size of 1220 mm×1400 mm as shown in FIG. 1 according to the procedure shown in the above-mentioned embodiment. and a second reflection suppressing layered layer and a mask base provided with a light-shielding film.

The film-forming conditions of the first reflection suppressing layer were that the sputtering target was a Cr sputtering target, and the flow rate of the reactive gas was selected from the range of 5 to 45 sccm for the flow rate of the oxygen (O ₂ ) gas so as to achieve a metallic mode. The flow rate of nitrogen (N ₂ ) gas is selected from the range of 30 to 60 sccm, the flow rate of argon (Ar) gas is selected from the range of 60 to 150 sccm, and the applied power to the target is set to 2.0 to 6.0 kW, and the applied voltage to the target is set to Set to the range of 420~430V. In addition, the board|substrate conveyance speed at the time of film-forming of the 1st reflection suppression layer was made into 350 mm/min.

The film-forming conditions of the light-shielding layer are that the sputtering target is set to a Cr sputtering target, and the flow rate of the reactive gas is selected from the range of 1 to 60 sccm for the flow rate of the nitrogen (N ₂ ) gas so as to be a metal mode, so that argon ( The flow rate of Ar) gas was selected from the range of 60 to 200 sccm, and the target applied power was set to 3.0 to 7.0 kW, and the applied voltage was set to be in the range of 370 to 380 V. In addition, the board|substrate conveyance speed at the time of film-forming of the light-shielding layer was made into 200 mm/min.

The film-forming conditions of the second reflection suppressing layer were that the sputtering target was a Cr sputtering target, and the flow rate of the reactive gas was selected from the range of 8 to 45 sccm so that the flow rate of the oxygen (O ₂ ) gas would be in the metal mode. The flow rate of nitrogen (N ₂ ) gas is selected from the range of 30 to 60 sccm, the flow rate of argon (Ar) gas is selected from the range of 60 to 150 sccm, and the target applied power is set to 2.0 to 6.0 kW, and the target applied voltage is set to It is in the range of 420~430V. In addition, the board|substrate conveyance speed at the time of film-forming of the 2nd reflection suppression layer was made into 300 mm/min.

As for 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 results of composition analysis in the film thickness direction in the mask base of Example 1, the horizontal axis represents the sputtering time, and the vertical axis represents the element content [atomic %]. The sputtering time represents the depth from the surface of the light-shielding film.

In Figure 2, the area from the surface to the depth of about 5min (minutes) is the surface natural oxide layer, the area from the depth of about 5min (minutes) to the depth of about 16min (minutes) is the second reflection suppression layer, from the depth of about The area from 16min (minute) to the depth of about 40min (minute) is the transition layer, the area from the depth of about 40min (minute) to the depth of about 97min (minute) is the shading layer, from the depth of about 97min (minute) to the depth of about 124min The area up to (minutes) is the transition layer, the area from the depth of about 124 minutes (minutes) to the depth of about 132 minutes (minutes) is the first reflection suppression layer, and the area from the depth of about 132 minutes (minutes) is the transparent substrate.

In addition, the film thickness of the light-shielding film measured by the film thickness meter is 198 nm, and the film thicknesses of 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 The surface natural oxide layer 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, and contains 55.4 atomic % of Cr, 20.8 atomic % of N, and 23.8 atomic % of O. The content of these elements was measured at the portion where N in the first reflection suppressing layer became a peak (the region where the sputtering time was 123 min (minutes)). The first reflection suppressing layer has an inclined composition as shown in FIG. 2 , and has a portion where the O content increases and the N content decreases toward the transparent substrate in the film thickness direction. Furthermore, in the first reflection suppressing layer, the average content of each element in the film thickness direction was 57 atomic % for Cr, 18 atomic % for N, and 25 atomic % for O.

The light-shielding layer is a CrN film containing 92.0 atomic % of Cr and 8.0 atomic % of N. The content of these elements was measured at the central portion (the region where the sputtering time was 69 min (minutes)) in the film thickness direction of the light shielding layer. In addition, in the light-shielding layer, the average content of each element in the film thickness direction was 91 atomic % for Cr and 9 atomic % for N.

The second reflection suppression layer is a CrON film, and contains 50.7 atomic % of Cr, 12.2 atomic % of N, and 37.1 atomic % of O. The content of these elements was measured at the center portion of the region where O increased in the second reflection suppressing layer (the region where the sputtering time was 16 min (minutes)). The second reflection suppressing layer has an inclined 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. In addition, in the second reflection suppressing layer, the average content of each element in the film thickness direction was 52 atomic % for Cr, 17 atomic % for N, and 31 atomic % for O. In addition, it is considered that a surface natural oxide layer is formed on the surface of the second reflection suppressing layer by exposure to the atmosphere, and this layer is oxidized or carbonized, so that relatively high O content and C content are detected.

Further, based on the results of the XPS measurement, spectral analysis was performed on the bonding state (chemical state) of each of the first reflection suppressing layer, the light shielding layer, and the second reflection suppressing layer constituting the light shielding film. As a result, the first reflection suppression layer and the second reflection suppression layer contain chromium nitride (CrN), chromium (III) oxide (Cr ₂ O ₃ ), and chromium oxide (VI) (CrO ₃ ), and also contain chromium, oxygen and Nitrogen-based chromium-based materials (chromium compounds). Moreover, the light-shielding layer is a chromium-based material (chromium compound) containing chromium (Cr) and dichromium nitride (Cr ₂ N) and containing chromium and nitrogen.

(Assessment of Photomask Base)

About the mask base of Example 1, the optical density of a light-shielding film, and the reflectance of the front and back of a 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 with a spectrophotometer (“SolidSpec-3700” manufactured by Shimadzu Corporation), and as a result, the g-ray ( 5.0 in wavelength 436nm). Moreover, the reflectance of the front and back of a light-shielding film was measured with a spectrophotometer ("SolidSpec-3700" by Shimadzu Corporation). Specifically, the reflectance on the second reflection suppressing 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, respectively. As a result, the reflectance spectrum shown in FIG. 3 was obtained. 3 shows the reflectance spectrum of the front and back surfaces of the mask 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 mask substrate of Example 1, it was confirmed that the bottom peak wavelength of the reflectance spectrum of the front and back surfaces was near 436 nm, and the reflectance was greatly reduced for light with a wide range of wavelengths. Specifically, in the wavelength range of 365nm to 436nm, the front reflectance of the light-shielding film is 10.0% or less (7.7% (wavelength 365nm), 1.8% (wavelength 405nm), 1.1% (wavelength 413nm), 0.3% (wavelength 436nm)) , The back reflectivity of the light-shielding film is less than 7.5% (6.2% (wavelength 365nm), 4.7% (wavelength 405nm), 4.8% (wavelength 436nm)). It has been confirmed that the reflectance of the front and back of the light-shielding film can be reduced to 10% or less at a wavelength of 365 nm to 436 nm. In particular, the reflectivity of the light with a wavelength of 436 nm can be reduced to 0.3% for the front and 0.3% for the back. 4.8%.

(Evaluation of shading film pattern)

Using the mask base of Example 1, a light-shielding film pattern was formed on the 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 processing were performed to form a resist pattern. Then, the resist pattern is used as a mask, and wet etching is performed with a chromium etchant to form a light-shielding film pattern on the transparent substrate. Evaluation of the light-shielding film pattern was performed by forming a 1.9 μm line and space 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. FIG. 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 mask substrate of Example 1, and respectively represents the just etching time (JET) as a reference (100%) , the cross-sectional shape after over-etching was performed with etching time of 110%, 130%, and 150%. In FIG. 4 , it was confirmed that a light-shielding film pattern and a resist film pattern were laminated on the transparent substrate. When the side surface of the light-shielding film pattern was JET 100%, the angle formed with the transparent substrate was 70°. It was confirmed that the angle formed is in the range of 60° to 80° even when the etching time is 110%, 130% and 150% of JET, and the cross-sectional shape of the light-shielding film pattern can be adjusted regardless of the etching time. The stable formation becomes vertical.

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

(The production of the mask)

Next, a photomask was fabricated using the photomask substrate of Example 1.

First, a phenolic-based positive resist is formed on the light-shielding film of the photomask substrate. Then, using a laser drawing device, a pattern of a circuit pattern for a TFT panel is drawn on the resist film, and further By developing and rinsing, a specific resist pattern (the minimum line width of the above-mentioned circuit pattern is 0.75 μm) is formed.

Then, the resist pattern is used as a mask, the light-shielding film is patterned by wet etching using a chromium etching solution, and finally the resist pattern is peeled off with a resist stripping solution to obtain a light-shielding film formed on a transparent substrate. Photomask for film pattern (mask pattern).

The CD uniformity of the light shielding film pattern of the photomask was measured by "SIR8000" manufactured by Seiko Electronic Nanotechnology Co., Ltd. The measurement of CD uniformity was performed at the position of 11×11 with respect to the area of 1100 mm×1300 mm excluding the peripheral area of the substrate.

As a result, the CD uniformity was 100 nm, and the obtained mask had good CD uniformity.

(Production of LCD panel)

The photomask produced in Example 1 was set on a mask stage of an exposure device, and pattern exposure was performed on a transfer target body having a resist film formed on a substrate for a display device (TFT) to produce a TFT. array. As exposure light, composite light of wavelength 300 nm or more and 550 nm or less including i-rays of wavelength 365 nm, h rays of wavelength 405 nm, and g rays of wavelength 436 nm was used.

A TFT-LCD panel is fabricated by combining the fabricated TFT array with a color filter, a polarizer, and a backlight. As a result, a TFT-LCD panel without display unevenness was obtained.

<Example 2> (fabrication of mask base)

In this embodiment, a photomask base is produced in the same manner as in Embodiment 1, except that a semi-transparent film is formed between the transparent substrate and the light-shielding film. Specifically, at 1220mm×1400mm After forming the semi-transparent film on the transparent substrate, 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 producing a mask base of Example 2.

The semi-transparent film is formed by using the sputtering target as a MoSi sputtering target, and forming molybdenum silicide nitride by reactive sputtering using a mixed gas of argon (Ar) gas and nitrogen (N ₂ ) gas. film (MoSiN). The semi-transparent 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, 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 semi-transparent film to produce a mask base of Example 2.

(Assessment of Photomask Base)

Regarding the mask substrate of Example 2, the optical density and the reflectivity of the front and back surfaces of the laminated film composed of the semi-transparent film and the light-shielding film were evaluated by the same method as that of 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 was 5.0 or more. In addition, at wavelengths of 365 nm to 436 nm, the reflectance (front reflectance) on the light-shielding film side of the laminated film is 10.0% or less (7.7% (wavelength 365nm), 1.8% (wavelength 405nm), 1.1% (wavelength 413nm), 0.3 % (wavelength 436nm)), and the reflectance (backside reflectance) on the semi-transparent film side is 30.0% or less (27.4% (wavelength 365nm), 22.5% (wavelength 405nm), 20.1% (wavelength 436nm)).

(The production of the mask)

Next, a photomask was fabricated using the photomask substrate of Example 2. The mask is formed with a semi-transparent film pattern on a transparent substrate, a light-shielding film pattern is formed on the semi-transparent film pattern, and has a transfer pattern including a light-transmitting portion, a light-shielding portion, and a semi-transparent portion. The mask of Example 2 is obtained by the patent No. Manufactured by the method for producing a gray-tone mask described in No. 4934236. The CD uniformity of the semi-transparent film pattern and the light-shielding film pattern of the obtained mask was good.

(Production of LCD panel)

Using the mask produced in Example 2, an LCD panel was produced in the same manner as in Example 1. As a result, a TFT-LCD panel without display unevenness was obtained. Furthermore, as the manufacturing method of the photomask of Example 2, it can be produced by the photomask manufacturing method described in Patent No. 5,605,917, and the semi-transparent film pattern and light shielding of the photomask obtained by this method can be used. The CD uniformity of the film pattern was also good. Also, a TFT-LCD panel with less display unevenness is obtained.

<Comparative Example 1>

As a comparative example, on a transparent substrate having a substrate size of 1220 mm×1400 mm, a first reflection suppressing layer, a light shielding layer, and a second reflection suppressing layer were laminated to form a photomask base provided with a light shielding film.

The film-forming conditions of the first reflection suppressing layer were that the sputtering target was a Cr sputtering target, and the flow rate of the reactive gas was selected from the range of 150 to 300 sccm for the flow rate of the oxygen (O ₂ ) gas in a reaction mode. The flow rate of nitrogen (N ₂ ) gas is selected from the range of 150~300sccm, the flow rate of methane (CH ₄ ) gas is selected from the range of 5~15sccm, and the flow rate of argon (Ar) gas is selected from the range of 100~150sccm, And the target applied electric power is set to the range of 2.0-7.0kW. In addition, the board|substrate conveyance speed at the time of film-forming the 1st reflection suppression layer was 200 mm/min, and film-forming was performed three times.

The film-forming conditions of the light-shielding layer are that the sputtering target is set to a Cr sputtering target, and the flow rate of the reactive gas is selected from the range of 1 to 60 sccm for the flow rate of the nitrogen (N ₂ ) gas so as to be a metal mode, so that argon ( The flow rate of Ar) gas was selected from the range of 60 to 200 sccm, and the target applied power was set to the range of 5.0 to 8.0 kW. In addition, the board|substrate conveyance speed at the time of film-forming of the light-shielding layer was made into 200 mm/min.

The film-forming conditions of the second reflection suppressing layer were that the sputtering target was a Cr sputtering target, and the flow rate of the reactive gas was selected from the range of 150 to 300 for the flow rate of the oxygen (O ₂ ) gas so as to be a reaction mode. The flow rate of nitrogen (N ₂ ) gas is selected from the range of 150~300sccm, the flow rate of methane (CH ₄ ) gas is selected from the range of 5~15sccm, and the flow rate of argon (Ar) gas is selected from the range of 100~150sccm, And the target applied electric power is set to the range of 2.0-7.0kW. In addition, the substrate conveyance speed at the time of film-forming of the 2nd reflection suppression layer was set to 200 mm/min, and film-forming was performed three times.

The film thickness of the light-shielding film measured by a film thickness meter was 206 nm. In addition, 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 thickness of the second reflection suppression layer is about 51 nm, the light shielding layer is about 101 nm, and the first reflection suppression layer is about 101 nm. is about 51 nm. Moreover, between the 2nd reflection suppression layer and the light-shielding layer, and between the light-shielding layer and the 1st reflection suppression layer, the transition layer in which the composition of each element is inclined continuously is formed.

About the light-shielding film of the mask base of the comparative example 1, the content rate of the element contained in each layer was measured, and the result is as follows. In addition, the content rate of each layer shown below shows the average content rate of the film thickness direction of each element.

The first reflection suppression layer is a CrON film, which contains 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, which contains 45 atomic % of Cr, 3 atomic % of N, and 52 atomic % of O.

The optical density of the light-shielding film and the reflectance of the front and back surfaces of the light-shielding film were measured in the same manner as in the above-mentioned Example 1 with respect to the mask base of Comparative Example 1. As a result, the optical density of the light-shielding film was 3.5% in g-ray (wavelength 436 nm) which is the wavelength region of exposure light, and 4.5% in i-ray (wavelength 365 nm). In addition, in the wavelength range of 365nm to 436nm, the front reflectivity of the light-shielding film is 5.0% or less (4.5% (wavelength 365nm), 4.0% (wavelength 405nm), 3.5% (wavelength 436nm)), and the backside reflectance of the light-shielding film is 7.5 % or less (5.5% (wavelength 365nm), 6.5% (wavelength 405nm), 7.5% (wavelength 436nm)).

Furthermore, the evaluation of the light-shielding film pattern was performed similarly to Example 1. As a result, the side surface of the light-shielding film pattern has a tapered shape in the vicinity of the transparent substrate and an inverted tapered shape in the vicinity of the resist film, resulting in a very poor cross-sectional shape. In addition, it was confirmed that the angle formed with the transparent substrate was 150° when the JET was 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 photomask was measured, and the result was poor at 200 nm. In this way, in the mask substrate 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 described above, in the light-shielding film of the mask base, each of the first reflection suppressing layer, the light-shielding layer and the second reflection suppressing layer is formed of a material having a specific composition, and each of the front and back surfaces of the light-shielding film is reflective The film thickness of each layer is set so that the ratio is 10% or less, and the optical density is 3.0 or more, and a mask base is formed, whereby a mask with good CD uniformity and high precision can be obtained when a mask is produced by etching. hood pattern. According to such a mask, a display device with less display unevenness can be produced.

1: Photomask base

11: Transparent substrate

12: shading film

13: 1st reflection suppression layer

14: shading layer

15: Second reflection suppression layer

Claims (16)

A photomask substrate, characterized in that: it is a photomask substrate used in the manufacture of photomasks used in the manufacture of display devices, and has: A transparent substrate composed of a material that is substantially transparent with respect to exposure light; a light-shielding film, which is disposed 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 suppression layer from the transparent substrate side, The first reflection suppressing 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 atomic %. The composition of atomic %, The second 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 of atomic %, The reflectance of the front and back surfaces of the light-shielding film with respect to the exposure wavelength of the exposure light is respectively 10% or less, the reflectance on the front side is lower than the reflectance on the back side, and the optical density is set to be 3.0 or more. The film thickness of the said 1st reflection suppression layer, the said light shielding layer, and the said 2nd reflection suppression layer. The photomask substrate according to claim 1, wherein the first reflection suppressing layer and the second reflection suppressing layer respectively have at least one element of oxygen and nitrogen, and the composition changes continuously or step by step along the film thickness direction. area. The photomask substrate according to claim 1 or 2, wherein the second reflection suppressing layer has a region in which the oxygen content increases toward the light shielding layer side in the film thickness direction. The photomask substrate according to claim 1 or 2, wherein the second reflection suppressing layer has a region where the nitrogen content decreases toward the light shielding layer side in the film thickness direction. The photomask substrate according to claim 1 or 2, wherein the first reflection suppressing layer has a region in which the oxygen content increases and the nitrogen content decreases toward the transparent substrate in the film thickness direction. The photomask substrate according to claim 1 or 2, wherein the second reflection suppressing layer is constituted so that the content of oxygen is higher than that of the first reflection suppressing layer. The photomask substrate of claim 1 or 2, wherein the light shielding layer comprises chromium (Cr) and chromium nitride (Cr ₂ N). The photomask substrate of claim 1 or 2, wherein the first reflection suppression layer and the second reflection suppression layer comprise chromium nitride (CrN), chromium (III) oxide (Cr ₂ O ₃ ) and chromium (VI) oxide (CrO ₃ ). The mask base according to claim 1 or 2, further comprising a semi-transparent film having an optical density lower than that of the light-shielding film between the transparent substrate and the light-shielding film. The photomask base according to claim 1 or 2, further comprising a phase shift film between the transparent substrate and the light shielding film. A method of manufacturing a photomask, characterized in that it has the following steps: preparing the above-mentioned reticle substrate as in any one of claims 1 to 10; and A resist film is formed on the said light-shielding film, and the said light-shielding film is etched using the resist pattern formed from the said resist film as a mask, and the light-shielding film pattern is formed on the said transparent substrate. A method of manufacturing a photomask, characterized in that it has the following steps: Prepare the above-mentioned photomask substrate as claimed in claim 9; forming a resist film on the above-mentioned light-shielding film, etching the above-mentioned light-shielding film using the resist pattern formed from the above-mentioned resist film as a mask to form a light-shielding film pattern on the above-mentioned semi-transparent film; and The above-mentioned light-shielding film pattern is used as a mask to etch the above-mentioned semi-transparent film to form a semi-transparent film pattern on the above-mentioned transparent substrate. A method of manufacturing a photomask, characterized in that it has the following steps: Prepare the above-mentioned photomask substrate as claimed in claim 10; forming a resist film on the above-mentioned light-shielding film, etching the above-mentioned light-shielding film using the resist pattern formed from the above-mentioned resist film as a mask, and forming a light-shielding film pattern on the above-mentioned phase shift film; and The phase shift film pattern is formed on the transparent substrate by etching the phase shift film using the light shielding film pattern as a mask. The method for manufacturing a photomask according to any one of claims 11 to 13, wherein in the photomask, the light shielding film is a gate electrode or a wiring pattern of a source electrode/drain electrode in a TFT array. The method for manufacturing a photomask according to any one of claims 11 to 13, wherein in the photomask, the aperture ratio of the light-shielding film pattern is 50% or more. A method of manufacturing a display device, characterized by having an exposure step of placing a mask obtained by the method of manufacturing a mask according to any one of claims 11 to 15 on a mask of an exposure device A stage for exposing and transferring the mask pattern of the light-shielding film pattern formed on the photomask to the resist formed on the display device substrate.

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