KR102365488B1 - Photomask blank and method of manufacturing photomask blank, method of manufacturing photomask, and method of manufacturing display deⅵce - Google Patents

Abstract

Provided is a photomask blank that satisfies optical properties capable of obtaining a high-precision mask pattern when fabricating a photomask by etching and suppressing display unevenness when fabricating a display device using the photomask.
A photomask blank used when manufacturing a photomask for manufacturing a display device, comprising: a transparent substrate comprising a material substantially transparent to exposure light; and a material formed on the transparent substrate and comprising a material substantially opaque to exposure light a light shielding film, the light shielding film comprising a first reflection suppressing layer, a light blocking layer, and a second reflection suppressing layer from the side of the transparent substrate, the first reflection suppressing layer being a chromium-based material containing chromium, oxygen and nitrogen, the content of chromium has a composition of 25 to 75 atomic %, an oxygen content of 15 to 45 atomic %, and a nitrogen content of 10 to 30 atomic %, the light-shielding layer is a chromium-based material containing chromium and nitrogen, and a chromium content of 70 to 95 atomic %, nitrogen content of 5 to 30 atomic %, the second reflection suppressing layer is a chromium-based material containing chromium, oxygen and nitrogen, the content of chromium is 30 to 75 atomic %, and the content of oxygen is 20 to 50 atomic %, nitrogen content of 5 to 20 atomic %, the first surface and the back surface of the light shielding film have a reflectance of 10% or less with respect to the exposure wavelength of the exposure light, respectively, and the optical density is 3.0 or more. A photomask blank characterized in that the film thicknesses of the reflection suppression layer, the light shielding layer, and the second reflection suppression layer are set.

Description

A photomask blank and its manufacturing method, a photomask manufacturing method, and a manufacturing method of a display device TECHNICAL FIELD

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

DESCRIPTION OF RELATED ART In display devices, such as FPD (Flat Panel Display) which are representative of LCD (Liquid Crystal Display), high-definition and high-speed display are progressing rapidly along with a large screen and wide viewing angle. One of the elements necessary for such high-definition and high-speed display is the production of fine and high-dimensional precision elements and electronic circuit patterns such as wiring. Photolithography is often used for patterning this electronic circuit for a display device. For this reason, the photomask for display device manufacture in which the fine and high-precision pattern was formed is needed.

A photomask for manufacturing a display device is produced from a photomask blank. The photomask blank is constituted by forming a light-shielding film made of a material opaque to exposure light on a transparent substrate made of synthetic quartz glass or the like. In a photomask blank or a photomask, in order to suppress reflection of light when exposed, a reflection suppression layer is formed on the front and back both surfaces of a light shielding film, The photomask blank is 1st reflection suppression in order from the transparent substrate side, for example. It has a film structure in which a layer, a light-shielding layer, and a second reflection suppressing layer are laminated. The photomask is produced by patterning the light-shielding film of the photomask blank by wet etching or the like to form a predetermined mask pattern.

Patent Document 1 discloses a photomask for manufacturing such a display device, a photomask blank used as the original plate, and a technique related to a manufacturing method of both.

Korean Patent No. 10-1473163 Publication

In the manufacture of a display device (for example, a display panel for a TV), for example, by using a photomask to transfer a predetermined pattern to a substrate for a display device, then slide the substrate for a display device and transfer the predetermined pattern, Pattern transfer is repeated. In this transfer, when the exposure light is incident on the photomask from the light source of the exposure apparatus, the reflected light on the back side of the photomask, or the reflected light from the object to be transferred after the exposure light passes through the photomask is returned to the front side of the photomask. Under the influence of , exposure light greater than expected may be irradiated in the vicinity of the overlap of the display device. As a result, in a display device manufactured by exposing adjacent patterns so as to partially overlap each other, display nonuniformity may occur.

Therefore, in the photomask blank, the reflectance of the front and back surfaces of the light shielding film is 10% or less (for example, wavelength 365 nm to 436 nm), more preferably 5% or less (for example, 400 nm to 436 nm) in order to suppress display unevenness nm) is required. In addition, from the viewpoint of improving the CD uniformity of the photomask, considering the surface reflection of the light-shielding film in laser writing light, the reflectance of the surface of the light-shielding film is 5% or less (for example, wavelength 413 nm), more preferably 3% It is calculated|required to set it as the following (for example, wavelength 413nm).

In addition to the demand for high-definition and high-speed display of the display device, the size of the substrate is progressing in the photomask for manufacturing the display device, and in recent years, a super-large photomask using a rectangular substrate having a short side length of 850 mm or more has been used as a display device. is used in the manufacture of In addition, as the above-mentioned large-sized photomasks having a short side length of 850 mm or more, there are 850 mm × 1200 mm size for G7, 1220 mm × 1400 mm size for G8, and 1620 mm × 1780 mm size for G10. As a CD uniformity of the mask pattern in a photomask, a high-precision mask pattern of 100 nm or less is calculated|required.

In the previously proposed photomask blank of Patent Document 1, when the short side length of the substrate is 850 mm or more, the reflectance of the front and back surfaces of the light-shielding film is set to 10% or less with respect to the exposure wavelength, and a photomask blank is used. The requirement that the CD uniformity of the mask pattern in the produced photomask be 100 nm or less could not be satisfied.

The present invention provides a photomask blank that satisfies optical properties in which a high-precision mask pattern is obtained when a photomask is manufactured by etching, and display unevenness can be suppressed when a display device is manufactured using the photomask. aim to do

(Configuration 1)

It is a photomask blank used when manufacturing a photomask for manufacturing display devices,

A transparent substrate comprising a material substantially transparent to exposure light;

a light-shielding film formed on the transparent substrate and comprising a material substantially opaque to the exposure light;

The light blocking film includes a first reflection suppressing layer, a light blocking layer, and a second reflection suppressing 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%. have a composition,

The light-shielding layer is a chromium-based material containing chromium and nitrogen, and has a composition in which the content of chromium is 70 to 95 atomic% and the content of nitrogen is 5 to 30 atomic%,

The second reflection suppressing 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%. have a composition,

Film thicknesses of the first reflection suppressing layer, the light blocking layer, and the second reflection suppressing layer such that the reflectance of the exposure light on the front surface and the back surface of the light shielding film with respect to the exposure wavelength is 10% or less, and the optical density is 3.0 or more, respectively A photomask blank, characterized in that it is set.

(Configuration 2)

The first reflection suppressing layer has a chromium content of 50 to 75 atomic%, an oxygen content of 15 to 35 atomic%, and a nitrogen content of 10 to 25 atomic%,

The photomask blank according to Configuration 1, wherein the second reflection suppressing layer has a chromium content of 50 to 75 atomic%, an oxygen content of 20 to 40 atomic%, and a nitrogen content of 5 to 20 atomic%. .

(Configuration 3)

The first reflection suppressing layer and the second reflection suppressing layer each have a region in which the content of at least one of oxygen and nitrogen is continuously or stepwisely changed in composition along the film thickness direction, Configuration 1 or The photomask blank as described in 2.

(Configuration 4)

The photomask blank according to any one of Configurations 1 to 3, 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.

(Configuration 5)

The photomask blank according to any one of Configurations 1 to 4, wherein 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.

(Configuration 6)

The photomask according to any one of Configurations 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. blank.

(Configuration 7)

The photomask blank according to any one of Configurations 1 to 6, wherein the second reflection suppression layer is configured such that the oxygen content is higher than that of the first reflection suppression layer.

(Configuration 8)

The photomask blank according to any one of Configurations 1 to 7, wherein the first reflection suppression layer is configured such that the nitrogen content is higher than that of the second reflection suppression layer.

(Configuration 9)

The photomask blank according to any one of Configurations 1 to 8, wherein the light-shielding layer contains chromium (Cr) and dichromium nitride (Cr ₂ N).

(Configuration 10)

wherein the first reflection suppressing layer and the second reflection suppressing layer include chromium mononitride (CrN), chromium (III) oxide (Cr ₂ O ₃ ), and chromium (VI) oxide (CrO ₃ ), The photomask blank according to any one of Configurations 1 to 9.

(Configuration 11)

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, The photomask blank according to any one of Configurations 1 to 10.

(Configuration 12)

The photomask blank according to any one of Configurations 1 to 11, further comprising, between the transparent substrate and the light-shielding film, a semi-transmissive film having an optical density lower than the optical density of the light-shielding film.

(Configuration 13)

A phase shift film is further provided between the said transparent substrate and the said light-shielding film, The photomask blank in any one of structures 1-11 characterized by the above-mentioned.

(Configuration 14)

A photomask used when manufacturing a photomask for manufacturing a display device in which a light-shielding film made of a material substantially opaque to exposure light is formed by sputtering on a transparent substrate comprising a material substantially transparent to exposure light A method for manufacturing a blank,

A chromium-based material containing chromium, oxygen, and nitrogen by reactive sputtering using a sputtering target containing chromium on the transparent substrate, an oxygen-based gas, a reactive gas containing a nitrogen-based gas, and a sputtering gas containing a rare gas and forming a first reflection suppressing layer having a composition 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%;

A chromium-based material containing chromium and nitrogen 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 on the first reflection suppression layer, A step of forming a light-shielding layer having a composition in which the content of chromium is 70 to 95 atomic % and the content of nitrogen is 5 to 30 atomic %;

A chromium-based material containing chromium, oxygen, and nitrogen by reactive sputtering using a sputtering target containing chromium on the light-shielding layer, and a sputtering gas containing a reactive gas containing an oxygen-based gas, a nitrogen-based gas, and a rare gas and forming a second reflection suppressing layer having a composition having 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%;

In the reactive sputtering, a flow rate of the reactive gas contained in the sputtering gas is selected to be a metal mode, and the reflectance of the exposure light on the surface and the back surface of the light shielding film to the exposure wavelength is 10% or less, respectively, and the optical density is A method for manufacturing a photomask blank, characterized in that the film thicknesses of the first reflection suppressing layer, the light blocking layer and the second reflection suppressing layer are formed to be 3.0 or more.

(Configuration 15)

The method for producing a photomask blank according to Configuration 14, wherein the oxygen-based gas is an oxygen (O ₂ ) gas.

(Configuration 16)

The first reflection suppressing layer, the light blocking layer and the second reflection suppressing layer are formed using an in-line sputtering apparatus that forms the light blocking film while the transparent substrate moves relative to the sputtering target. , A method for producing a photomask blank according to configuration 14 or 15.

(Configuration 17)

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

(configuration 18)

A phase shift film is formed between the said transparent substrate and the said light shielding film, The manufacturing method of the photomask blank in any one of structures 14-16 characterized by the above-mentioned.

(Configuration 19)

A step of preparing the photomask blank according to any one of Configurations 1 to 11;

A process of forming a resist film on the light-shielding film and etching the light-shielding film using the resist pattern formed from the resist film as a mask to form a light-shielding film pattern on the transparent substrate

A method of manufacturing a photomask, characterized in that it has a.

(Configuration 20)

A step of preparing the photomask blank according to configuration 12;

forming a resist film on the light-shielding film and etching the light-shielding film using the resist pattern formed from the resist film as a mask to form a light-shielding film pattern on the transparent substrate;

A process of forming a semi-transmissive layer pattern on the transparent substrate by etching the semi-transmissive layer using the light blocking layer pattern as a mask

A method of manufacturing a photomask, characterized in that it has a.

(Configuration 21)

A step of preparing the photomask blank according to configuration 13;

forming a resist film on the light-shielding film and etching the light-shielding film using the resist pattern formed from the resist film as a mask to form a light-shielding film pattern on the transparent substrate;

The process of forming a phase shift film pattern on the said transparent substrate by etching the said phase shift film using the said light shielding film pattern as a mask

A method of manufacturing a photomask, characterized in that it has a.

(Configuration 22)

The photomask obtained by the manufacturing method of the photomask in any one of the structures 19-21 is mounted on the mask stage of exposure apparatus, The said light-shielding film pattern formed on the said photomask, the said semitransmissive film pattern, the said phase shift film pattern A method of manufacturing a display device, comprising an exposure step of exposing and transferring at least one mask pattern to a resist formed on a display device substrate.

ADVANTAGE OF THE INVENTION According to this invention, it is excellent in pattern precision, and the photomask blank which can manufacture the photomask which has the optical characteristic which can suppress display unevenness at the time of manufacture of a display apparatus is obtained.

BRIEF DESCRIPTION OF THE DRAWINGS It is sectional drawing which shows the schematic structure of the photomask blank which concerns on one Embodiment of this invention.
It is a figure which shows the composition analysis result in the film thickness direction in the photomask blank of Example 1. FIG.
3 is a diagram showing reflectance spectra of the front and back surfaces of the photomask blank of Example 1. FIG.
4 is a view for explaining the characteristics of a cross-sectional shape of a light-shielding film pattern of a photomask manufactured using the photomask blank of Example 1. FIG.
Fig. 5 is a schematic diagram for explaining a film-forming mode in the case of forming a light-shielding film by reactive sputtering.

EMBODIMENT OF THE INVENTION Hereinafter, embodiment of this invention is described concretely, referring drawings. In addition, the following embodiment is one form at the time of realizing this invention, and does not limit this invention within the range. In addition, the same code|symbol is attached|subjected to the same or corresponding part in drawing, and the description may be simplified or abbreviate|omitted in some cases.

<Photomask Blank>

A photomask blank according to an embodiment of the present invention will be described. The photomask blank of the present embodiment is light of a short wavelength selected from, for example, a wavelength range of 300 nm to 550 nm, or light of a plurality of wavelengths (eg, j-line (wavelength 313 nm), i-line (wavelength 365) nm), h-line (405 nm), and g-line (wavelength 436 nm)) are used when manufacturing a photomask for manufacturing a display device that is exposed to complex light. In addition, in this specification, the numerical range represented using "to" means a range including the numerical value described before and after "to" as a lower limit and an upper limit.

BRIEF DESCRIPTION OF THE DRAWINGS It is sectional drawing which shows the schematic structure of the photomask blank which concerns on one Embodiment of this invention. The photomask blank 1 includes a transparent substrate 11 and a light-shielding film 12 . Hereinafter, as a photomask blank according to an embodiment of the present invention, a binary type photomask blank 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 light-transmitting substrate. As the transmittance with respect to the exposure wavelength, 85% or more, preferably 90% or more of the substrate material is used. As a material which forms the transparent substrate 11, synthetic quartz glass, soda-lime glass, alkali free glass, and low thermal expansion glass are mentioned, for example.

What is necessary is just to change the magnitude|size of the transparent substrate 11 suitably according to the magnitude|size requested|required of the photomask for display apparatus manufacture. For example, as the transparent substrate 11, it is a rectangular-shaped board|substrate, and the length of the short side can use the transparent substrate 11 which is a magnitude|size of 330 mm or more and 1620 mm or less. As the transparent substrate 11, the size is, for example, 330 mm x 450 mm, 390 mm x 610 mm, 500 mm x 750 mm, 520 mm x 610 mm, 520 mm x 800 mm, 800 x 920 mm, 850 mm x Substrates of 1200 mm, 850 mm x 1400 mm, 1220 mm x 1400 mm, and 1620 mm x 1780 mm can be used. In particular, it is preferable that the length of the short side of the board|substrate is 850 mm or more and 1620 mm or less. By using such a transparent substrate 11, the photomask for display apparatus manufacture of G7-G10 is obtained.

(light-shielding film)

The light-shielding film 12 is constituted by laminating a first reflection suppressing layer 13 , a light blocking layer 14 , and a second reflection suppressing layer 15 in order from the transparent substrate 11 side. In addition, below, the transparent substrate 11 side of the photomask blank 1 is made into a back surface side, and the light-shielding film 12 side is demonstrated as a front side side.

The first reflection suppressing layer 13 is formed on the surface of the light blocking layer 14 on the side close to the transparent substrate 11 , and is a photomask manufactured using the photomask blank 1 . It is arranged on the side close to the exposure light source when pattern transfer is performed using When exposure treatment is performed using a photomask, the pattern transfer image is transferred to the resist film formed on the substrate for a display device as a transfer target by irradiating exposure light from the transparent substrate 11 side (back side) of the photomask. do. At this time, when the exposure light is reflected from the back side of the light-shielding film pattern, it becomes stray light of the mask pattern, which is the light-shielding film pattern, and deterioration of the transfer image such as formation of a ghost image or an increase in the amount of flare occurs, or in the vicinity of the overlap of the substrate for a display device. , display unevenness may occur by being irradiated with exposure light more than expected. 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 photomask, thereby suppressing the deterioration of the transfer image and contributing to the improvement of the transfer characteristics In addition, in the overlapping vicinity of the board|substrate for display apparatuses, generation|occurrence|production of the display nonuniformity by the exposure light more than expected irradiating can be suppressed.

The light blocking layer 14 is formed between the first reflection suppressing layer 13 and the second reflection suppressing layer 15 in the light blocking film 12 . The light-shielding layer 14 has a function of adjusting so that the light-shielding film 12 has an optical density for becoming substantially opaque with respect to the exposure light. Here, being substantially opaque to exposure light means a light-shielding property of 3.0 or more in terms of optical density, and from the viewpoint of transfer properties, preferably, the optical density is 4.0 or more, more preferably 4.5 or more.

The second reflection suppressing layer 15 is provided on the surface of the light-shielding layer 14 that is farther from the transparent substrate 11 in the light-shielding film 12 . The second reflection suppressing layer 15 forms a resist film thereon, and when writing a predetermined pattern on the resist film with the writing light (laser light) of a writing apparatus (for example, a laser writing apparatus), the light-shielding film 12 ) can be suppressed, so that the CD uniformity of the resist pattern and the mask pattern formed based thereon can be improved. In addition, when used as a photomask, the second reflection suppressing layer 15 is disposed on the side of the substrate for a display device as a transfer object, and the light reflected from the transfer object is reflected back on the surface side of the light shielding film 12 of the photomask. It suppresses the return to the transfer object and contributes to the improvement of the transfer characteristics by suppressing the deterioration of the transfer image, and in the vicinity of the overlapping of the display device substrate, the occurrence of display unevenness due to irradiation with exposure light greater than expected. can be suppressed

(Material of light-shielding film)

Next, the material of each layer in the light shielding film 12 is demonstrated.

The first reflection suppressing layer 13 is made of a chromium-based material containing chromium, oxygen, and nitrogen. Oxygen in the first reflection suppressing layer 13 exerts an effect of reducing the reflectance of the exposure light from the back surface side. In addition to the effect of reducing the reflectance of the exposure light from the back side, nitrogen in the first reflection suppressing layer 13 vertically verticalizes the cross section of the light-shielding film pattern formed by etching (particularly wet etching) using a photomask blank. While making it close to , the effect of increasing the CD uniformity is exhibited. Moreover, you may make it contain carbon and fluorine further from the viewpoint of controlling an etching characteristic.

The light shielding layer 14 is made of a chromium-based material containing chromium and nitrogen. Nitrogen in the light-shielding layer 14 reduces the etching rate difference between the first reflection suppression layer 13 and the second reflection suppression layer 15 and is etched (particularly wet etching) using a photomask blank. While making the cross section of the light-shielding film pattern to be formed approach perpendicular|vertical, the etching time in the light-shielding film 12 (all) is shortened, and the effect of improving CD uniformity is exhibited. Moreover, from the viewpoint of controlling an etching characteristic, you may make it contain oxygen, carbon, and fluorine further.

The second reflection suppressing layer 15 is made of a chromium-based material containing chromium, oxygen, and nitrogen. Oxygen in the 2nd reflection suppression layer 15 exhibits the effect of reducing the reflectance of the writing light of the writing apparatus from the surface side, and the reflectance of the exposure light from the front side. Moreover, the adhesiveness with a resist film is improved, and the effect of side etching suppression by permeation of the etchant from the interface of a resist film and the light shielding film 12 is exhibited. In addition to the effect of reducing the reflectance of the writing light from the surface side and the reflectance of the exposure light from the surface side, nitrogen in the second reflection suppressing layer 15 is etched (particularly wet etching) using a photomask blank. While the cross section of the light-shielding film pattern to be formed is made to approach perpendicular|vertical, the effect of improving CD uniformity is exhibited. Moreover, from the viewpoint of controlling an etching characteristic, you may make it contain carbon and fluorine further.

(Composition of light-shielding film)

Next, the composition of each layer in the light-shielding film 12 is demonstrated. In addition, let the content rate of each element mentioned later be the value measured by X-ray photoelectric spectroscopy (XPS).

In the light blocking film 12, the first reflection suppressing layer 13 contains chromium (Cr) at a content of 25 to 75 atomic%, oxygen (O) at 15 to 45 atomic%, and nitrogen (N) at a content of 10 to 30 atomic%. The light blocking layer 14 contains chromium (Cr) at a content of 70 to 95 atomic% and nitrogen (N) at a content of 5 to 30 atomic%, respectively, and the second reflection suppressing layer 15 includes chromium (Cr) ) is configured to contain 30 to 75 atomic%, oxygen (O) of 20 to 50 atomic%, and nitrogen (N) in a content of 5 to 20 atomic%, respectively. Preferably, the first reflection suppressing layer 13 contains Cr at a content of 50 to 75 atomic%, O at 15 to 35 atomic%, and N at a content of 10 to 25 atomic%, respectively, and the second reflection suppressing layer 15 ) contains 50 to 75 atomic % of Cr, 20 to 40 atomic % of O, and 5 to 20 atomic % of N, respectively.

Each of the first reflection suppressing layer 13 and the second reflection suppressing layer 15 preferably has a region in which the content of at least one of O and N is continuously or stepwisely changed in composition along the film thickness direction.

The second reflection suppressing layer 15 preferably has a region in which the O content (oxygen content) increases toward the light blocking layer 14 side in the film thickness direction.

Moreover, it is preferable that the 2nd reflection suppression layer 15 has a region where the N content (nitrogen content) decreases toward the light shielding layer 14 side in the film thickness direction.

Moreover, it is preferable that the 1st reflection suppression layer 13 has a region where the N content decreases while the O content increases toward the transparent substrate 11 in the film thickness direction.

In addition, in the photomask blank 1 and the photomask produced therefrom, the reflectance of the front and back surfaces of the light-shielding film 12 or the light-shielding film pattern is further reduced, and from the viewpoint of reducing the difference in the reflectance, the second reflection suppressing layer 15 ) is preferably configured to have a higher O content than the first reflection suppressing layer 13 , and the first reflection suppressing layer 13 is configured to have a higher N content than the second reflection suppressing layer 15 . desirable. Specifically, it is preferable to make the O content of the second reflection suppressing layer 15 higher than that of the first reflection suppressing layer 13 by 5 atomic % or more, more preferably 10 atomic % or more. Moreover, it is preferable to make the N content of the 1st reflection suppression layer 13 larger than the 2nd reflection suppression layer 15 by 5 atomic% or more, More preferably, it is preferable to make it 10 atomic% or more larger. Moreover, when the 1st reflection suppression layer 13 and the 2nd reflection suppression layer 15 have a compositional gradient area|region, the O content rate and N content rate represent the average density|concentration in the film thickness direction.

Moreover, in the 1st reflection suppression layer 13, the light shielding layer 14, and the 2nd reflection suppression layer 15, although the change of the content rate of each element may be either continuous or stepwise, it is preferable that it is continuous.

(About the bond state (chemical state))

The light blocking layer 14 preferably contains chromium (Cr) and dichromium nitride (Cr ₂ N).

The first reflection suppressing layer 13 and the second reflection suppressing layer 15 include chromium mononitride (CrN), chromium (III) oxide (Cr ₂ O ₃ ), and chromium (VI) oxide (CrO ₃ ). it is preferable

(About film thickness)

In the light-shielding film 12 , the thickness of each of the first reflection suppressing layer 13 , the light blocking layer 14 , and the second reflection suppressing layer 15 is not particularly limited, and the optical density required for the light blocking film 12 is What is necessary is just to adjust suitably according to a reflectance. The thickness of the first reflection suppressing layer 13 is determined by the reflection of light from the back surface side of the light blocking film 12 on the surface of the first reflection suppressing layer 13 , and the first reflection suppressing layer 13 and the light blocking layer. What is necessary is just the thickness at which the optical interference effect by reflection at the interface of the layer 14 is exhibited. On the other hand, the thickness of the second reflection suppressing layer 15 is determined with respect to the light from the surface side of the light shielding film 12 , the reflection at the surface of the second reflection suppressing layer 15 , the second reflection suppressing layer 15 and What is necessary is just the thickness at which the optical interference effect by reflection at the interface of the light shielding layer 14 is exhibited. The thickness of the light-shielding layer 14 should just be the thickness at which the optical density of the light-shielding film 12 becomes 3 or more. Specifically, from the viewpoint of setting the optical density to 3.0 or more while the reflectance of the front and back surfaces with respect to the exposure wavelength of the light shielding film 12 is 10% or less, for example, the film thickness of the first reflection suppressing layer 13 is 15 What is necessary is just to set the thickness of the light shielding layer 14 to 50 nm to 120 nm, and the thickness of the second reflection suppressing layer 15 to 10 nm to 60 nm.

<Manufacturing method of photomask blank>

Next, the manufacturing method of the photomask blank 1 mentioned above is demonstrated.

(Preparation process)

A transparent substrate 11 that is substantially transparent to exposure light is prepared. In addition, the transparent substrate 11 may perform arbitrary processing processes, such as a grinding process and a grinding|polishing process, as needed so that it may become a flat and smooth main surface. After polishing, cleaning may be performed to remove foreign substances and contamination on the surface of the transparent substrate 11 . As the washing, for example, sulfuric acid, sulfuric acid peroxide (SPM), ammonia, ammonia peroxide (APM), OH radical washing water, ozone water, hot water and the like can be used.

(Step of forming the first reflection suppressing layer)

Subsequently, the first reflection suppressing layer 13 is formed on the transparent substrate 11 . This formation forms a film by reactive sputtering using the sputtering target containing Cr, and the sputtering gas containing the reactive gas containing oxygen type gas, nitrogen type gas, and a rare gas. At this time, as the film-forming condition, a flow rate at which the flow rate of the reactive gas contained in the sputtering gas becomes the metal mode is selected.

Here, the metal mode will be described with reference to FIG. 5 . 5 is a schematic diagram for explaining a film formation mode in the case of forming a thin film by reactive sputtering, the abscissa is the partial pressure (flow rate) ratio of the reactive gas in the mixed gas of the rare gas and the reactive gas, and the ordinate is the applied to the target represents the voltage. 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 , a reaction mode in which the supply amount (ratio) of the reactive gas is larger than any threshold, a metal mode in which the supply amount (ratio) of the reactive gas is smaller than the reaction mode, and a supply amount (ratio) of the reactive gas ), there is a transition mode that sets between the reaction mode and the metal mode. In the metal mode, by reducing the proportion of the reactive gas, adhesion of the reactive gas to the target surface can be reduced, and the film formation rate can be increased. In addition, in the metal mode, since the amount of reactive gas supplied is small, for example, a film having a lower O concentration (oxygen concentration) or N concentration (nitrogen concentration) than a film having a stoichiometric composition can be formed. That is, a film having a relatively high Cr content and a low O content or N content can be formed.

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

As a sputtering target, what is necessary is just to contain Cr, For example, other than chromium metal, chromium-type materials, such as chromium oxide, chromium nitride, and chromium oxynitride, can be used. As the oxygen-based gas, for example, oxygen (O ₂ ), carbon dioxide (CO ₂ ), nitrogen oxide gas (N ₂ O, NO, NO ₂ ), or the like can be used. Among these, it is preferable to use oxygen (O ₂ ) gas from the viewpoint of high oxidizing power. In addition, nitrogen (N ₂ ) or the like can be used as the nitrogen-based gas. As the rare gas, for example, helium gas, neon gas, argon gas, krypton gas, and xenon gas may be used. In addition to the reactive gas, a hydrocarbon-based gas may be supplied, for example, methane gas, butane gas, or the like can be used.

In the present embodiment, by setting the flow rate of the reactive gas and the power applied to the sputtering target to the metal mode conditions, and performing a film forming process by reactive sputtering using a sputtering target containing Cr, on the transparent substrate 11 , Cr is 25 to 75 atomic%, O is 15 to 45 atomic%, and N is formed in the first reflection suppressing layer 13 each at a content rate of 10 to 30 atomic%.

In the case where the first reflection suppressing layer 13 is formed as a single film having 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 O content or N content in the film thickness direction What is necessary is just to change suitably the kind and flow volume of a reactive gas, the ratio of oxygen-type gas in reactive gas, nitrogen-type gas, etc., when making a composition inclination so that this may change. Moreover, you may change the arrangement|positioning of a gas supply port, a gas supply method, etc.

(Process of forming a light-shielding layer)

Subsequently, the light blocking layer 14 is formed on the first reflection suppressing layer 13 . This formation performs film-forming by reactive sputtering using the sputtering target containing Cr, and the sputtering gas containing nitrogen-type gas and a rare gas. At this time, as the film-forming condition, a flow rate at which the flow rate of the reactive gas contained in the sputtering gas becomes the metal mode is selected.

What is necessary is just to contain Cr as a target, For example, chromium-type materials, such as chromium oxide, chromium nitride, and chromium oxynitride other than a chromium metal, can be used. 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, and xenon gas may be used. In addition to the reactive gas, the above-described oxygen-based gas and hydrocarbon-based gas may be supplied.

In this embodiment, the flow rate of the reactive gas and the power applied to the sputtering target are set to the conditions of the metal mode, and reactive sputtering is performed using a sputtering target containing Cr. On the first reflection suppression layer 13, The light blocking layer 14 each containing Cr in a content ratio of 70 to 95 atomic% and N in a content ratio of 5 to 30 atomic% is formed.

Moreover, as film-forming conditions of the light-shielding layer 14, what is necessary is just to set the flow volume of a nitrogen-based gas to 1-60 sccm, and to set the flow volume of a rare gas to 60-200 sccm, for example. In addition, the target applied power may be 3.0 to 7.0 kW, and the applied voltage to the target may be 370 to 380 V.

(Step of forming the second reflection suppressing layer)

Subsequently, the second reflection suppressing layer 15 is formed on the light blocking layer 14 . In this formation, similarly to the first reflection suppression layer 13, the flow rate of the reactive gas and the target applied power are set to the conditions of the metal mode, and a film is formed by reactive sputtering using a sputtering target containing Cr. . Thereby, on the light-shielding layer 14, the second reflection suppressing layer 15 each containing 30 to 75 atomic % of Cr, 20 to 50 atomic % of O, and 5 to 20 atomic % of N is formed. to form

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

In addition, when the composition of the second reflection suppressing layer is inclined, as described above, 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 may be appropriately changed.

The photomask blank 1 of this embodiment is obtained by the above.

In addition, what is necessary is just to perform film-forming of each layer in the light-shielding film 12 in-situ using an in-line sputtering apparatus. In the case of not an in-line sputtering apparatus, it is necessary to take out the transparent substrate 11 out of the apparatus after film formation of each layer, and the transparent substrate 11 is exposed to the atmosphere, so that each layer may be surface oxidized or surface carbonized. . As a result, the reflectance and etching rate with respect to the exposure light of the light shielding film 12 may be changed. In this respect, in the case of an in-line sputtering device, since each layer can be continuously formed without taking out the transparent substrate 11 and exposing to the atmosphere by taking it out of the device, unintentional introduction of elements into the light-shielding film 12 can be suppressed. there is.

In addition, when the light-shielding film 12 is formed using an in-line sputtering apparatus, the composition of the first reflection suppressing layer 13, the light blocking layer 14, and the second reflection suppressing layer 15 is continuously inclined. Since it has a composition gradient region (transition layer), it is preferable because the cross section of the light-shielding film pattern formed by etching (particularly wet etching) using a photomask blank is smooth and can be brought close to vertical.

<Method for manufacturing a photomask>

Next, the method of manufacturing a photomask using the photomask blank 1 mentioned above is demonstrated.

(resist film formation process)

First, a resist is apply|coated on the 2nd reflection suppression layer 15 in the light shielding film 12 of the photomask blank 1, and it dries, and forms a resist film. Although it is necessary to select an appropriate thing according to the drawing apparatus to be used as a resist, a positive type or a negative type resist can be used.

(resist pattern formation process)

Then, a predetermined pattern is drawn on the resist film using a drawing apparatus. Usually, when producing the photomask for display apparatus manufacture, a laser drawing apparatus is used. After drawing, the resist film is developed and rinsed to form a predetermined resist pattern.

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

(Formation process of mask pattern)

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

In this embodiment, 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 blocking layer 14, and the second reflection suppressing layer 15 are identical, Therefore, the cross-sectional shape at the time of wet etching, that is, the cross-sectional shape of the light-shielding film pattern (mask pattern) can be made close to perpendicular to the transparent substrate 11, and high CD uniformity can be obtained.

(Peeling process)

Then, the resist pattern is peeled, and the photomask in which the light-shielding film pattern (mask pattern) was formed on the transparent substrate 11 is obtained.

As described above, the photomask according to the present embodiment is obtained.

<Method for manufacturing display device>

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

(Preparation process)

First, with respect to a substrate having a resist film, on which a resist film is formed on a substrate of a display device, the photomask obtained by the above-described method for manufacturing a photomask is disposed to face the resist film formed on the substrate through the projection optical system of the exposure apparatus Then, it is mounted on the mask stage of the exposure apparatus.

(Exposure process (pattern transfer process))

Next, a photomask is irradiated with exposure light to perform a resist exposure step of transferring the pattern to the resist film formed on the substrate of the display device.

The exposure light is, for example, light of a short wavelength selected from a wavelength region of 300 nm to 550 nm (j-line (wavelength 313 nm), i-line (wavelength 365 nm), h-line (wavelength 405 nm), g-line (wavelength) 436 nm), or light of a plurality of wavelengths (eg, j-line (wavelength 313 nm), i-line (wavelength 365 nm), h-line (405 nm), g-line (wavelength 436 nm)). Composite light is used. In the present embodiment, since the display device (display panel) is manufactured using a photomask in which the reflectance of the front and back surfaces of the light-shielding film pattern (mask pattern) is reduced, a display device (display panel) without display unevenness can be obtained.

<Effect according to the present embodiment>

According to this embodiment, one or more effects shown below are exhibited.

(a) In the photomask blank 1 of this embodiment, the light blocking film 12 is formed by laminating|stacking the 1st reflection suppression layer 13, the light-shielding layer 14, and the 2nd reflection suppression layer 15, The first reflection suppressing layer 13 is a chromium-based material containing chromium, oxygen, and nitrogen, and has a Cr content of 25 to 75 atomic%, O content of 15 to 45 atomic%, and N content of 10 to 30 atomic%. The light blocking layer 14 is a chromium-based material containing chromium and nitrogen, and has a composition in which the Cr content is 70 to 95 atomic% and the N content is 5 to 30 atomic%, and the second reflection suppressing layer 15 is chromium. It is a chromium-based material containing oxygen and nitrogen, and has a composition having a Cr content of 30 to 75 atomic %, O content of 20 to 50 atomic %, and N content of 5 to 20 atomic %. In addition, the thickness of the 1st reflection suppression layer 13 and the 2nd reflection suppression layer 15 is made into the thickness at which the optical interference effect is obtained as much as possible or close to the maximum. Thereby, the reflectance with respect to the exposure wavelength of the front and back surfaces of the photomask blank 1 can be reduced, and it can be set to 10 % or less, respectively. Specifically, in the reflectance spectrum of the front and back surfaces, the wavelength of the bottom peak at which the reflectance is minimal is set to 380 nm to 480 nm on the relatively high wavelength side, and the reflectance of light having a wavelength of 380 nm to 480 nm is 10% or less, preferably can be less than 7.5%. On the other hand, by making the light-shielding layer 14 into a predetermined thickness, the optical density in the light-shielding film 12 can be made into 3.0 or more.

(b) Further, in this embodiment, by appropriately changing the composition of the first reflection suppressing layer 13 and the second reflection suppressing layer 15 within the above-described range, the back side of the photomask blank 1 (transparent substrate ( 11) side) and the surface side (light-shielding film 12 side) reflectance can be adjusted, respectively. For example, the reflectance of the photomask blank 1 can be adjusted so that the front side becomes higher than the back side, the front side and the back side become equal, or the back side becomes higher than the front side, respectively. In addition, from the viewpoint of suppressing the influence of the reflection of exposure light from the photomask to the light source side (generation of ghost, etc.) when exposing the object to be transferred using the produced photomask, the reflectance on the back side is higher than that on the front side. It is preferable to do In other words, it is preferable to make the reflectance of the front surface side (light-shielding film 12 side) of the photomask blank 1 lower than the reflectance of the back surface side (transparent substrate 11 side). Specifically, when transferring the wiring pattern of the gate electrode or the source electrode/drain electrode in the TFT array to the resist film formed on the substrate of the display device as the transfer target, the aperture ratio of the light blocking film pattern of the photomask is 50% or more Therefore, since the amount of exposure light passing through the photomask is increased, flare due to the return light of the exposure light from the side to be transferred is likely to occur. Therefore, the reflectance of the surface and the back surface of the light shielding film 12 of the photomask blank 1 with respect to the exposure wavelength is 10% or less, respectively, and the reflectance of the surface side of the light shielding film 12 is made lower than the reflectance of the back side. The influence can be reduced, and a CD error at the time of manufacturing a display device using a photomask can be prevented.

(c) In addition, in this embodiment, each layer of the 1st reflection suppression layer 13, the light blocking layer 14, and the 2nd reflection suppression layer 15 which comprises the light shielding film 12 is made into the said composition range, and is etched By reducing the concentration of O which lowers the rate and N which increases the etching rate, the difference in the etching rate of each layer can be suppressed and matched. Thereby, the cross-sectional shape of the photomask blank 1 when the light-shielding film 12 is etched, that is, the cross-sectional shape of the mask pattern can be made close to perpendicular to the transparent substrate 11 . Specifically, in the cross-sectional shape of the mask pattern, when an angle between the side surface formed by etching and the transparent substrate 11 is Θ, Θ can be within the range of 90°±30°. Further, while bringing the cross-sectional shape of the mask pattern close to vertical, etching residual mule of the first reflection suppressing layer 13 or erosion of the first reflection suppressing layer 13 and the second reflection suppressing layer 15 (so-called undercut) ), side etching, etc. can be suppressed. As a result, the CD uniformity in the mask pattern (light-shielding film pattern) can be improved, and a high-precision mask pattern of 100 nm or less can be formed.

(d) In this embodiment, the light-shielding film 12 is etched in each of the first reflection suppressing layer 13 , the light blocking layer 14 , and the second reflection suppressing layer 15 constituting the light-shielding film 12 . By matching the rates, it is possible to stably ensure the verticality of the cross-sectional shape, irrespective of the length of the etching time, the light and shade of the etching solution, or the temperature of the etching solution. For example, when the just etching time of the light shielding film 12 is T, even when overetching is performed with the etching time of 1.5 x T, verticality equivalent to that of the case where the etching time is 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 when the cross section is over-etched at the etching time 1.5 × T can be set to 10° or less. . Similarly, when the concentration of the etching solution is increased and the concentration of the etching solution is decreased, the difference between the angles formed by the cross section of the light-shielding film pattern can be 10° or less. Similarly, when the temperature of the etchant is increased (for example, 42°C) and when the temperature of the etchant is lowered (for example, 23°C, which is room temperature), the etching rate increases as the temperature of the etchant increases, but the light-shielding film The difference between the angles formed by the cross-section of the pattern may be 10° or less. In addition, the just etching time represents the etching time until the light shielding film 12 is etched in the film thickness direction and the surface of the transparent substrate 11 begins to be exposed.

(e) In the light-shielding film 12, the first reflection suppressing layer 13 and the second reflection suppressing layer 15 are chromium-based materials containing chromium, oxygen, and nitrogen, and the first reflection suppressing layer 13 is 50 to 75 atomic% of Cr, 15 to 35 atomic% of O, and 10 to 25 atomic% of N, respectively, and the second reflection suppressing layer 15 contains 50 to 75 atomic% of Cr and 20 of O It is preferable to include each of the N in a content of 5 to 20 atomic% to 40 atomic %.

In the first reflection suppressing layer 13 and the second reflection suppressing layer 15 , by further reducing the O content, it is possible to suppress an excessive increase in the etching rate due to containing O in these layers. Therefore, the light blocking layer 14 is applied to the light blocking layer 14 for the purpose of matching the etching rates of the first reflection suppressing layer 13, the light blocking layer 14, and the second reflection suppressing layer 15 constituting the light blocking film 12 . The content of carbon (C) to be blended can be reduced, or the light shielding layer 14 can be made carbon-free without containing C. As a result, the content rate of Cr in the light shielding layer 14 can be raised, and optical density (OD) can be maintained high.

On the other hand, in the first reflection suppressing layer 13 and the second reflection suppressing layer 15, by further reducing the N content, an excessive increase in the etching rate due to the N in these layers can be suppressed. there is. Therefore, the light blocking layer 14 is applied to the light blocking layer 14 for the purpose of matching the etching rates of the first reflection suppressing layer 13, the light blocking layer 14, and the second reflection suppressing layer 15 constituting the light blocking film 12 . The content rate of N to contain can be reduced. As a result, the content rate of Cr in the light shielding layer 14 can be raised, and optical density (OD) can be maintained high.

(f) Each of the first reflection suppressing layer 13 and the second reflection suppressing layer 15 has a region in which the content of at least one of O and N is continuously or stepwisely changed in composition along the film thickness direction. desirable. By changing the composition of each layer of the first reflection suppressing layer 13 and the second reflection suppressing layer 15, a region having a high content of O or N is locally introduced into each layer, while The average content of O or N can be kept low. Thereby, the reflectance of the front side and back side of the photomask blank 1 can be kept low.

In addition, in each of the first reflection suppressing layer 13 , the light blocking layer 14 , and the second reflection suppressing layer 15 constituting the light blocking film 12 , when the O content increases, the etching rate excessively increases, or N When the content rate becomes high, the etching rate increases excessively. However, by making the content rate of O or N low, the difference in the etching rate of each layer by containing these elements can be suppressed. That is, the deviation of the etching rate between the 1st reflection suppression layer 13 and the 2nd reflection suppression layer 15, and the light shielding layer 14 can be suppressed. As a result, the light blocking layer 14 is applied to the light blocking layer 14 for the purpose of matching the etching rates of the first reflection suppressing layer 13 , the light blocking layer 14 , and the second reflection suppressing layer 15 constituting the light blocking film 12 . The N and carbon to contain can be reduced, or the light shielding layer 14 can be made carbon-free without containing carbon. As a result, the content rate of Cr in the light shielding layer 14 can be raised, and optical density (OD) can be maintained high.

(g) The second reflection suppressing layer 15 preferably has a region in which the O content increases toward the light-shielding layer 14 side in the film thickness direction. Thereby, in the 2nd reflection suppression layer 15, the O content rate of the interface part with the light shielding layer 14 is made high locally, and the average O content rate in the film thickness direction is made low. As a result, while obtaining a desired reflectance on the surface side (second reflection suppressing layer 15) of the light shielding film 12, it is possible to suppress erosion due to excessive etching at the interface.

(h) It is preferable that the 2nd reflection suppression layer 15 has the area|region in which N content falls toward the light-shielding layer 14 side in the film thickness direction. As a result, in the second reflection suppressing layer 15 , while maintaining the average N content in the film thickness direction to some extent, the N content in the interface portion 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 blocking layer 14 can be suppressed.

(i) It is preferable that the 1st reflection suppression layer 13 has a region where the N content decreases while the O content increases toward the transparent substrate 11 in the film thickness direction. In the first reflection suppression layer 13 , the etching rate can be gradually lowered toward the transparent substrate 11 by increasing the O content rate and decreasing the N content rate toward the transparent substrate 11 in the film thickness direction. . Thereby, erosion at the interface of the 1st reflection suppression layer 13 and the transparent substrate 11 can be suppressed, and the CD uniformity of a mask pattern can be improved more.

(j) The second reflection suppressing layer 15 is preferably configured to have a higher O content than the first reflection suppressing layer 13 . Specifically, it is preferable that the O content of the second reflection suppressing layer 15 is greater than that of the first reflection suppressing layer 13 by 5 atomic % or more, more preferably 10 atomic % or more. Moreover, it is preferable that the 1st reflection suppression layer 13 is comprised so that N content may become higher than the 2nd reflection suppression layer 15. As shown in FIG. Specifically, it is preferable that the N content of the first reflection suppressing layer 13 is greater than that of the second reflection suppressing layer 15 by 5 atomic % or more, more preferably by 10 atomic % or more. According to the studies of the present inventors, when the first reflection suppressing layer 13 and the second reflection suppressing layer 15 are formed of the same material, the reflectance on the front side tends to be higher than that on the back side despite the same composition. was found to be Then, when the composition ratio (O content rate, N content rate) of each layer of the 1st reflection suppression layer 13 and the 2nd reflection suppression layer 15 was further investigated, the 1st reflection suppression layer 13 and the 2nd reflection suppression layer It was found that by making the composition ratio (O content, N content) of the suppression layer 15 as described above, the reflectance on the back side can be reduced to the same degree as on the front side or lower than the front side. Thus, by changing the composition ratio (O content rate, N content rate) of each layer, the reflectance of the front and back surfaces can be controlled.

(k) Further, according to this embodiment, the light-shielding layer 14 is preferably made of a chromium-based material in a bonding state (chemical state) containing chromium (Cr) and dichromium nitride (Cr ₂ N). By making the light-shielding layer 14 a chromium-based material in a bonded state (chemical state) containing Cr and Cr ₂ N, excessive progress of the etching rate when the light-shielding layer 14 contains a predetermined amount of N is suppressed. This can be done, and the cross-sectional shape of the light-shielding film pattern can be made close to vertical.

(l) Further, according to the present embodiment, the first reflection suppressing layer 13 and the second reflection suppressing layer 15 include chromium mononitride (CrN), chromium (III) oxide (Cr ₂ O ₃ ) and chromium oxide. It is preferable to use a chromium-based material in a bonding state (chemical state) containing (VI) (CrO ₃ ). When the first reflection suppressing layer 13 and the second reflection suppressing 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, it is possible to suppress an excessive decrease in the etching rate by the above-described chromium oxide, so that the cross-section of the light-shielding film pattern The shape can be approximated to vertical.

(m) Furthermore, according to this embodiment, the 1st reflection suppression layer 13 and the 2nd reflection suppression layer 15 are sputtering target containing Cr, and the sputtering gas containing oxygen type gas, nitrogen type gas, and a rare gas. Film formation is performed by reactive sputtering using And as a film-forming condition of these reactive sputtering, the flow volume at which the flow volume of the reactive gas contained in sputtering gas becomes a metal mode is selected. Thereby, it is easy to adjust each layer of the 1st reflection suppression layer 13, the light-blocking layer 14, and the 2nd reflection suppression layer 15 which comprises the light-shielding film 12 to the said composition range, and also the light-shielding film 12 ) while effectively reducing the reflectance of the front and back surfaces, the cross-sectional shape of the light-shielding film pattern when the light-shielding film 12 is patterned can be made 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. Since O ₂ gas has a higher oxidizing power compared to other oxygen-based gases, even when forming a film by selecting the metal mode, each layer can be more reliably adjusted within the composition range described above. Thereby, while effectively reducing the reflectance of the front and back surfaces of the light-shielding film 12, the cross-sectional shape of the light-shielding film pattern when the light-shielding film 12 is patterned can be made close to perpendicular|vertical.

(o) According to the photomask blank 1 of this embodiment, since the reflectance on the surface side is low, when a resist film is formed on the light shielding film 12, and a resist pattern is formed by a writing and developing process, the writing light of Reflection on the surface of the light-shielding film 12 can be reduced. Thereby, the dimensional accuracy of a resist pattern can be improved, and the dimensional accuracy of the light-shielding film pattern of the photomask formed from it can be improved.

(p) The photomask manufactured from the photomask blank 1 of this embodiment has a high-precision light-shielding film pattern, and the reflectance of the front and back surfaces of the light-shielding film pattern is reduced. characteristics can be obtained.

(q) In addition, in this embodiment, even when the photomask blank 1 is enlarged using a rectangular-shaped substrate having a short side length of 850 mm or more and 1620 mm or less as the transparent substrate 11, the light-shielding film 12 is Since it is comprised so that the etching rate in the film thickness direction may be matched, the CD uniformity of the mask pattern obtained by etching the light-shielding film 12 can be maintained high.

(r) Further, in the photomask of the present embodiment, the reflectance of the front and back surfaces of the light-shielding film pattern with respect to light selected from a wavelength range of 300 nm to 550 nm is 10% or less, preferably 7.5% or less, more preferably can be set to 5% or less, so even when the exposure light intensity is increased by, for example, exposing compound light containing i-line, h-line, and g-line, a transfer pattern with high precision for the transfer object can form. In addition, it is possible to prevent display unevenness caused by irradiating more than expected exposure light in the vicinity of the overlap of the transfer target object (eg, a display panel). Further, as the exposure light, there is a composite light including light of a plurality of wavelengths selected from a wavelength region of 300 nm to 550 nm, and a monochromatic light selected by cutting a certain wavelength region from a wavelength region of 300 nm to 550 nm with a filter or the like. , for example, composite light including j-line with a wavelength of 313 nm, i-line with a wavelength of 365 nm, h-line with a wavelength of 405 nm, and g-line with a wavelength of 436 nm, monochromatic light with i-line, and the like.

<Other embodiment>

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

Although the above-mentioned embodiment demonstrated the case where the light shielding film 12 was directly formed on the transparent substrate 11, this invention is not limited to this. For example, a photomask blank in which a semi-transmissive film having an optical density lower than that of the light-shielding film 12 is formed between the transparent substrate and the light-shielding film 12 may be used. This photomask blank can be used as a photomask blank for a gray tone mask or gradation mask having an effect of reducing the number of photomasks used in manufacturing a display device. The mask pattern in this gray tone mask or gradation mask becomes a semitransmissive film pattern and/or a light shielding film pattern.

Moreover, instead of a semitransmissive film, the photomask blank which formed the phase shift film which shifts the phase of transmitted light between the transparent substrate 11 and the light shielding film 12 may be sufficient. This photomask blank can be used as a phase shift mask which has the effect of the high pattern resolution by a phase shift effect. The mask pattern in this phase shift mask becomes a phase shift film pattern, a phase shift film pattern, and a light shielding film pattern.

As for the semitransmissive film and phase shift film mentioned above, the material which has etching selectivity with respect to the chromium-type material which is the material which comprises the light shielding film 12 is suitable. 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 oxygen, nitrogen, carbon, or fluorine A material comprising at least any one of the following is suitable. For example, metal silicide such as MoSi, ZrSi, TiSi, TaSi, oxide of metal silicide, nitride of metal silicide, oxynitride of metal silicide, carbonitride of metal silicide, oxycarbide of metal silicide, carbonization oxynitride of metal silicide Suitable. Moreover, the laminated|multilayer film comprised from the said film|membrane quoted as a functional film may be sufficient as these semitransmissive film and phase shift film.

As for the semitransmissive film and phase shift film mentioned above, the transmittance|permeability with respect to the exposure wavelength of exposure light can be adjusted suitably within 1 to 80% of range. In combination with the light-shielding film of this invention, it is preferable to make the transmittance|permeability with respect to the exposure wavelength of the above-mentioned semitransmissive film and the exposure light of a phase shift film 20 to 80 %. By selecting a semi-transmissive film and a phase shift film having a transmittance of 20 to 80% with respect to the exposure wavelength of exposure light and combining the light-shielding film of the present invention, a laminated film in which a semi-transmissive film and a light-shielding film are formed, or a laminate in which a phase shift film and a light-shielding film are formed The reflectance with respect to the exposure wavelength of the back surface in a film|membrane can be 40 % or less, More preferably, it can be made into 30 % or less.

Moreover, although the 1st reflection suppression layer 13 and the 2nd reflection suppression layer 15 demonstrated the case where both were each one layer in the above-mentioned embodiment, this invention is not limited to this. For example, it is good also considering each layer as two or more layers.

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

Further, in the above-described embodiment, between the transparent substrate 11 and the light-shielding film 12, the light-shielding film and the etching stopper film composed of a material having etching selectivity may be formed. The etching mask film and the etching stopper film are made of a material having an etching selectivity with respect to a chromium-based material, which is a material constituting the light-shielding film 12 . Examples of such a material include a metal silicide-based material containing molybdenum (Mo), zirconium (Zr), titanium (Ti), tantalum (Ta) and silicon (Si), Si, SiO, SiO ₂ , SiON, Si ₃ N ₄ and the like silicon-based materials are exemplified.

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>

(Production of photomask blank)

In this embodiment, using an in-line sputtering apparatus, according to the procedure shown in the above-described embodiment, as shown in Fig. 1, a first reflection suppressing layer on a transparent substrate having a substrate size of 1220 mm x 1400 mm; A photomask blank including a light-shielding film was manufactured by laminating a light-shielding layer and a second reflection suppressing layer.

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

The film formation conditions of the light shielding layer include a sputtering target as a Cr sputtering target, and a flow rate of the reactive gas such that the flow rate of the nitrogen (N ₂ ) gas is 1 to 60 sccm, and the flow rate of the argon (Ar) gas is 60 to 200 sccm so that the metal mode becomes a metal mode. While selecting each from the range of , the target applied power was set in the range of 3.0 to 7.0 kW, and the applied voltage was set 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 200 mm/min.

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

About the light-shielding film of the obtained photomask blank, when the composition in the film thickness direction was measured by X-ray photoelectron spectroscopy (XPS), it was confirmed that each layer in the light-shielding film has the composition distribution shown in FIG. Fig. 2 is a diagram showing the result of composition analysis in the film thickness direction in the photomask blank of Example 1, wherein the horizontal axis indicates sputtering time and the vertical axis indicates the element content [atomic %]. The sputtering time represents the depth from the surface of the light-shielding film.

In Fig. 2, a region from the surface to a depth of about 5 min (min) is the surface natural oxide layer, and a region from a depth of about 5 min (min) to a depth of about 16 min (min) is the second reflection suppressing layer, and a depth of about 16 min (min). ) to a depth of about 40 min (min) is a transition layer, a region from a depth of about 40 min (min) to a depth of about 97 min (min) is a light-shielding layer, and from a depth of about 97 min (min) to a depth of about 124 min (min) The region up to is the transition layer, the region from the depth of about 124 min (min) to the depth of about 132 min (min) is the first reflection suppressing layer, and the region from the depth of about 132 min (min) is the transparent substrate.

In addition, the film thickness of the light-shielding film measured with a film thickness meter was 198 nm, and the film thickness of each of the surface natural oxide layer, the second reflection suppressing layer, the transition layer, the light blocking layer, the transition layer, and the first reflection suppressing layer was, The oxide layer was approximately 4 nm, the second reflection suppressing layer was approximately 21 nm, the transition layer was approximately 35 nm, the light blocking layer was approximately 88 nm, the transition layer was approximately 39 nm, and the first reflection suppressing layer was approximately 11 nm.

As shown in FIG. 2 , the first reflection suppressing layer is a CrON film and contains 55.4 atomic% Cr, 20.8 atomic% N, and 23.8 atomic% O. The content of these elements was measured in the portion where N peaks in the first reflection suppressing layer (region where the sputtering time is 123 min (minutes)). The first reflection suppressing layer has a gradient composition as shown in Fig. 2, and has a portion in which the O content increases and the N content decreases toward the transparent substrate in the film thickness direction. Moreover, in the 1st reflection suppressing layer, the average content rate in the film thickness direction of each element was 57 atomic% for Cr, 18 atomic% for N, and 25 atomic% for O.

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

The second reflection suppressing layer is a CrON film and contains 50.7 atomic% Cr, 12.2 atomic% N, and 37.1 atomic% O. The content of these elements is measured in the central portion of the region in which O is increasing in the second reflection suppressing layer (region where the sputtering time is 16 min (min)). The second reflection suppressing layer has a gradient composition as shown in Fig. 2, and has a portion in which the O content increases and the N content decreases toward the light-shielding layer side in the film thickness direction. Moreover, in the 2nd reflection suppression layer, the average content rate in the film thickness direction of each element was 52 atomic% for Cr, 17 atomic% for N, and 31 atomic% for O. Further, on the surface of the second reflection suppressing layer, when exposed to the atmosphere, a surface natural oxide layer is formed, and since this layer is oxidized or carbonized, it is considered that the O content and the C content are detected to be high.

Further, the bonding state (chemical state) of each layer of the first reflection suppressing layer, the light blocking layer, and the second reflection suppressing layer constituting the light blocking film was analyzed by spectrum based on the XPS measurement result. As a result, the first reflection suppressing layer and the second reflection suppressing layer include chromium mononitride (CrN), chromium (III) oxide (Cr ₂ O ₃ ) and chromium (VI) oxide (CrO ₃ ), chromium and oxygen and a chromium-based material (chromium compound) containing nitrogen. In addition, the light-shielding layer was a chromium-based material (chromium compound) containing chromium (Cr) and dichromium nitride (Cr ₂ N), and containing chromium and nitrogen.

(Evaluation of photomask blank)

With respect to the photomask blank of Example 1, the optical density of the light-shielding film and the reflectance of the front and back surfaces of the light-shielding film were evaluated by the method shown below.

For the photomask blank of Example 1, when the optical density of the light-shielding film was measured with a spectrophotometer ("SolidSpec-3700" manufactured by Shimadzu Corporation), g-line (wavelength 436 nm) which is the wavelength region of the exposure light. ) was 5.0. In addition, the reflectance of the front and back surfaces of the light shielding film was measured with a spectrophotometer ("SolidSpec-3700" manufactured by Shimadzu Corporation). Specifically, the reflectance (surface reflectance) on the side of the second reflection suppressing layer of the light-shielding film and the reflectance (reverse reflectance) on the transparent substrate side of the light-shielding film were respectively measured with a spectrophotometer. As a result, a reflectance spectrum as shown in FIG. 3 was obtained. Fig. 3 shows reflectance spectra of the front and back surfaces of the photomask blank of Example 1, wherein the abscissa shows the wavelength [nm] and the ordinate shows the reflectance [%]. As shown in Fig. 3, the photomask blank of Example 1 can make the bottom peak wavelength of the reflectance spectrum of the front and back surfaces around 436 nm, and can greatly reduce the reflectance with respect to light of a wide wavelength. Confirmed. Specifically, at a wavelength of 365 nm to 436 nm, the surface reflectance of the light shielding film is 10.0% or less (7.7% (wavelength 365 nm), 1.8% (wavelength 405 nm), 1.1% (wavelength 413 nm), 0.3% (wavelength) 436 nm)), the back reflectance of the light-shielding film was 7.5% or less (6.2% (wavelength 365 nm), 4.7% (wavelength 405 nm), 4.8% (wavelength 436 nm)). At a wavelength of 365 nm to 436 nm, the reflectance of the front and back surfaces of the light-shielding film can be reduced to 10% or less, and in particular, for the reflectance with respect to light having a wavelength of 436 nm, the surface reflectance is 0.3%, and the back reflectance is 4.8%. It has been confirmed that there is

(Evaluation of light-shielding film pattern)

Using the photomask blank of Example 1, a light-shielding film pattern was formed on the transparent substrate. Specifically, after forming a novolak-type positive resist film on the light-shielding film on a transparent substrate, laser drawing (wavelength 413 nm) and developing process were carried out, and the resist pattern was formed. Thereafter, using the resist pattern as a mask, wet etching was performed with a chromium etching solution to form a light-shielding film pattern on the transparent substrate. The light-shielding film pattern was evaluated by forming a line and space pattern of 1.9 µm 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 brought close to the vertical. 4 is a view for explaining the verticality of the cross-sectional shape of the light-shielding film pattern by wet etching with respect to the photomask blank of Example 1, with the just etching time (JET) as a reference (100%), and the etching time The cross-sectional shape when over-etched as 110%, 130%, and 150% is shown, respectively. In FIG. 4 , it was confirmed that the light-shielding film pattern and the resist film pattern were laminated on the transparent substrate, and the side surface of the light-shielding film pattern had an angle of 70° with the transparent substrate when JET was 100%. These angles are within 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 stably formed vertically without depending on the etching time. It has been confirmed that there is

As in Example 1 above, on the light blocking film of the photomask blank, the first reflection suppressing layer, the light blocking layer, and the second reflection suppressing layer are laminated from the transparent substrate side, and each layer is configured to have a predetermined composition, so that the front and back surfaces while reducing the reflectance in a wide wavelength range, it was possible to form a vertical cross-sectional shape of the light-shielding film pattern when patterned by wet etching.

(Production of photomask)

Next, a photomask was manufactured using the photomask blank of Example 1.

First, a novolak-based positive resist was formed on the light-shielding film of the photomask blank. Then, a pattern of a circuit pattern for a TFT panel was drawn on this resist film using a laser drawing device, and further developed and rinsed to form a predetermined resist pattern (the minimum line width of the circuit pattern described above is 0.75 µm).

After that, using the resist pattern as a mask, the light-shielding film is patterned by wet etching using a chrome etchant, and finally the resist pattern is peeled off with the resist stripper, and the light-shielding film pattern (mask pattern) is formed on the transparent substrate. got a mask

The CD uniformity of the light-shielding film pattern of this photomask was measured by "SIR8000" by Seiko Instruments Nanotechnology Co., Ltd. CD uniformity was measured at a point of 11x11 for an area of 1100mm x 1300mm excluding the peripheral area of the substrate.

As a result, the CD uniformity was 100 nm, and the CD uniformity of the obtained photomask was good.

(Production of LCD panel)

The photomask manufactured in Example 1 was set on the mask stage of the exposure apparatus, and pattern exposure was performed with respect to the to-be-transferred object in which the resist film was formed on the board|substrate for display apparatus (TFT), and the TFT array was produced. As the exposure light, composite light having a wavelength of 300 nm or more and 550 nm or less was used, including i-line with a wavelength of 365 nm, h-line with a wavelength of 405 nm, and g-line with a wavelength of 436 nm.

A TFT-LCD panel was manufactured by combining the prepared TFT array, color filter, polarizing plate, and backlight. As a result, a TFT-LCD panel without display unevenness was obtained.

<Example 2>

(Production of photomask blank)

In this Example, a photomask blank was manufactured in the same manner as in Example 1 except that a semi-transmissive film was formed between the transparent substrate and the light-shielding film. Specifically, Example 2 was formed by forming a semitransmissive film on a transparent substrate of 1220 mm × 1400 mm and then laminating a first reflection suppressing layer, a light blocking layer and a second reflection suppressing layer under the same conditions as in Example 1. of photomask blanks were prepared.

The semi-transmissive film was formed by reactive sputtering with a mixed gas of argon (Ar) gas and nitrogen (N ₂ ) gas using a sputtering target as a MoSi sputtering target to form a molybdenum silicide nitride film (MoSiN). In this semitransmissive film, the composition ratio and the film thickness were suitably adjusted so that the transmittance|permeability might be set to 40 % in i line|wire (wavelength 365 nm).

Next, in the same manner as in Example 1, a light blocking film including a first reflection suppressing layer, a light blocking layer, and a second reflection suppressing layer was formed on the above-described semi-transmissive film to prepare a photomask blank of Example 2.

(Evaluation of photomask blank)

With respect to the photomask blank of Example 2, the optical density of the laminated film including the semi-transmissive film and the light-shielding film and the reflectance of the front and back surfaces were evaluated in the same manner as in Example 1 described above. As a result, the optical density of the laminated film in the g-line (wavelength 436 nm) which is the wavelength region of the exposure light was 5.0 or more. Further, at a wavelength of 365 nm to 436 nm, the reflectance (surface reflectance) on the light-shielding film side of the laminate film is 10.0% or less (7.7% (wavelength 365 nm), 1.8% (wavelength 405 nm), 1.1% (wavelength 413 nm), 0.3 % (wavelength 436 nm)), and the reflectance (rear reflectance) on the semi-transmissive film side was 30.0% or less (27.4% (wavelength 365 nm), 22.5% (wavelength 405 nm), 20.1% (wavelength 436 nm)).

(Production of photomask)

Next, a photomask was manufactured using the photomask blank of Example 2. This photomask includes a semi-transmissive film pattern on a transparent substrate, a light-shielding film pattern formed on the semi-transmissive film pattern, and a transfer pattern including a light-transmitting portion, a light-shielding portion, and a semi-transmissive portion. The photomask of Example 2 was manufactured by the manufacturing method of the gray tone mask described in Japanese Patent No. 4934236. The CD uniformity of the semi-transmissive film pattern and the light-shielding film pattern of the obtained photomask was good.

(Production of LCD panel)

Using the photomask manufactured in Example 2, it carried out similarly to Example 1, and produced the LCD panel. As a result, a TFT-LCD panel without display unevenness was obtained. Moreover, as the photomask manufacturing method of Example 2, it can manufacture by the manufacturing method of the photomask described in Japanese Patent No. 5605917, and the CD uniformity of the semi-transmissive film pattern and light-shielding film pattern of the photomask obtained by this method also becomes favorable. . And a TFT-LCD panel with little display nonuniformity is obtained.

<Comparative Example 1>

As a comparative example, the 1st reflection suppression layer, the light-shielding layer, and the 2nd reflection suppression layer were laminated|stacked on the transparent substrate whose board|substrate size is 1220 mm x 1400 mm, and the photomask blank provided with the light-shielding film was manufactured.

The film formation conditions of the first reflection suppression layer include a sputtering target as a Cr sputtering target, a flow rate of the reactive gas such that the flow rate of the oxygen (O ₂ ) gas is 150 to 300 sccm, and the flow rate of the nitrogen (N ₂ ) gas so as to be in a reaction mode. 150 to 300 sccm, the flow rate of methane (CH ₄ ) gas is 5 to 15 sccm, and the flow rate of argon (Ar) gas is selected from the range of 100 to 150 sccm, and the target applied power is set in the range of 2.0 to 7.0 kW did In addition, at the time of film-forming of the 1st reflection suppression layer, the board|substrate conveyance speed was 200 mm/min, and film-forming was performed 3 times.

The film formation conditions of the light shielding layer include a sputtering target as a Cr sputtering target, and a flow rate of the reactive gas such that the flow rate of the nitrogen (N ₂ ) gas is 1 to 60 sccm, and the flow rate of the argon (Ar) gas is 60 to 200 sccm so that the metal mode becomes a metal mode. While selecting each from the range of , the target applied power was set in 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 200 mm/min.

The film formation conditions of the second reflection suppression layer include a sputtering target as a Cr sputtering target, a flow rate of the reactive gas such that the flow rate of the oxygen (O ₂ ) gas is 150 to 300, and the flow rate of the nitrogen (N ₂ ) gas so as to be in a reaction mode. 150 to 300 sccm, the flow rate of methane (CH ₄ ) gas is 5 to 15 sccm, and the flow rate of argon (Ar) gas is selected from the range of 100 to 150 sccm, and the target applied power is set in the range of 2.0 to 7.0 kW did In addition, at the time of film-forming of the 2nd reflection suppression layer, the board|substrate conveyance speed was 200 mm/min, and film-forming was performed 3 times.

The film thickness of the light-shielding film measured by the film thickness meter was 206 nm. In addition, each film thickness of the surface natural oxide layer, the second reflection suppressing layer, the light blocking layer, and the first reflection suppressing layer is approximately 3 nm, the second reflection suppressing layer is approximately 51 nm, the light blocking layer is approximately 101 nm, and the first reflection suppressing layer is approximately 3 nm. This was about 51 nm. Further, between the second reflection suppressing layer and the light blocking layer, and between the light blocking layer and the first reflection suppressing layer, a transition layer in which the composition of each element is continuously inclined was formed.

About the light shielding film of the photomask blank of Comparative Example 1, when the content rate of the element contained in each layer was measured, it was as follows. In addition, the content rate of each layer shown below shows the average content rate in the film thickness direction of each element.

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

The light-shielding layer is a CrN film, and contains Cr at 78 atomic % and N at 22 atomic %.

The second reflection suppressing layer is a CrON film, and contains Cr at 45 atomic %, N at 3 atomic %, and O at 52 atomic %.

In the same manner as in Example 1 described above, for the photomask blank of Comparative Example 1, the optical density of the light-shielding film and the reflectance of the front and back surfaces of the light-shielding film were measured. As a result, the optical density of the light-shielding film was 3.5% in the g-line (wavelength 436 nm), which is the wavelength region of the exposure light, and 4.5% in the i-line (wavelength 365 nm). In addition, in the wavelength (365 nm to 436 nm), the surface reflectance of the light shielding film is 5.0% or less (4.5% (wavelength 365 nm), 4.0% (wavelength 405 nm), 3.5% (wavelength 436 nm)), the back reflectance of the light shielding film Silver was 7.5% or less (5.5% (wavelength 365 nm), 6.5% (wavelength 405 nm), 7.5% (wavelength 436 nm)).

Moreover, similarly to Example 1, the light-shielding film pattern was evaluated. As a result, the side surface of the light-shielding film pattern became tapered in the vicinity of the transparent substrate and in a reverse-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 at JET 100% was 150°.

Next, using the photomask blank of Comparative Example 1, a photomask was produced in the same manner as in Example 1. As a result of measuring the CD uniformity of the light-shielding film pattern of the obtained photomask, it became 200 nm, and it became a bad result. Thus, in the mask blank of Comparative Example 1, although the reflectance of the front and back surfaces could be reduced, a high-precision mask pattern could not be formed.

As described above, in the light blocking film of the photomask blank, each of the first reflection suppressing layer, the light blocking layer, and the second reflection suppressing layer is formed of a material having a predetermined composition, and the film thickness of each layer is determined in the table of the light blocking film When a photomask is produced by etching by setting the photomask blank to have a reflectance of 10% or less and an optical density of 3.0 or more on each back surface, a high-precision mask pattern can be obtained with good CD uniformity. can According to such a photomask, the display apparatus with little display nonuniformity can be produced.

1: Photomask blank
11: Transparent substrate
12: light shield
13: first reflection suppressing layer
14: light blocking layer
15: second reflection suppression layer

Claims (16)

It is a photomask blank used when producing a photomask for manufacturing a display device,
A transparent substrate comprising a material having a transmittance of 85% or more with respect to exposure light;
a light-shielding film formed on the transparent substrate and comprising a material substantially opaque to the exposure light;
The light shielding film includes a first reflection suppressing layer, a light blocking layer, and a second reflection suppressing 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 %. have a composition of
The second reflection suppressing 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 %. have a composition of
The reflectance of the exposure light to the exposure wavelength of the front and back surfaces of the light-shielding film is 10% or less, respectively, the light-shielding film side is the front side and the transparent substrate side is the back side, the reflectance of the front side is higher than the reflectance of the back side A photomask blank, wherein the film thicknesses of the first reflection suppressing layer, the light blocking layer, and the second reflection suppressing layer are set so as to be low and have an optical density of 3.0 or more. According to claim 1,
The first reflection suppressing layer and the second reflection suppressing layer each have a region in which the content of at least one of oxygen and nitrogen has a composition change continuously or stepwise along the film thickness direction. blank. 3. The method of claim 1 or 2,
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. 3. The method of claim 1 or 2,
The second reflection suppressing layer has a region in which the content of nitrogen decreases toward the light-shielding layer side in the film thickness direction. 3. The method of claim 1 or 2,
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. 3. The method of claim 1 or 2,
The second reflection suppressing layer is configured such that the oxygen content is higher than that of the first reflection suppressing layer. 3. The method of claim 1 or 2,
The light blocking layer, photomask blank comprising chromium (Cr) and 2 chromium nitride (Cr ₂ N). 3. The method of claim 1 or 2,
The first reflection suppression layer and the second reflection suppression layer include chromium mononitride (CrN), chromium (III) oxide (Cr ₂ O ₃ ), and chromium (VI) oxide (CrO ₃ ) photomask blank. 3. The method of claim 1 or 2,
A photomask blank characterized by further comprising a semi-transmissive film having an optical density lower than the optical density of the light-shielding film between the transparent substrate and the light-shielding film. 3. The method of claim 1 or 2,
A phase shift film is further provided between the said transparent substrate and the said light-shielding film, The photomask blank characterized by the above-mentioned. A step of preparing the photomask blank according to claim 1 or 2;
A process of forming a resist film on the light-shielding film and etching the light-shielding film using the resist pattern formed from the resist film as a mask to form a light-shielding film pattern on the transparent substrate
A method of manufacturing a photomask, characterized in that it has. A step of preparing the photomask blank according to claim 9;
forming a resist film on the light-shielding film, etching the light-shielding film using the resist pattern formed from the resist film as a mask to form a light-shielding film pattern on the semi-transmissive film;
A process of forming a semi-transmissive layer pattern on the transparent substrate by etching the semi-transmissive layer using the light blocking layer pattern as a mask
A method of manufacturing a photomask, characterized in that it has. A step of preparing the photomask blank according to claim 10;
The process of forming a resist film on the said light-shielding film, using the resist pattern formed from the said resist film as a mask, etching the said light-shielding film, and forming a light-shielding film pattern on the said phase shift film;
The process of forming a phase shift film pattern on the said transparent substrate by etching the said phase shift film using the said light shielding film pattern as a mask
A method of manufacturing a photomask, characterized in that it has. 12. The method of claim 11,
In the photomask, the light-shielding film pattern is a wiring pattern of a gate electrode or a source electrode/drain electrode in a TFT array. 12. The method of claim 11,
The photomask is a method of manufacturing a photomask, characterized in that the aperture ratio of the light-shielding film pattern is 50% or more. A photomask obtained by the method for manufacturing a photomask according to claim 11 is placed on a mask stage of an exposure apparatus, and the mask pattern of the light-shielding film pattern formed on the photomask is exposed and transferred to a resist formed on a display device substrate. A method of manufacturing a display device, comprising:

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