TWI676078B - Photomask blank, method of manufacturing photomask using same, and method of manufacturing display device - Google Patents

Abstract

The present invention provides a photomask base with less change in reflectivity relative to the ozone cleaning liquid, high cleaning resistance, and less defects in the light-shielding film including a reflection reduction layer, and a dimensional accuracy of the photomask pattern. Manufacturing method of high and low defect photomask. In addition, a method for manufacturing a high-definition display device with a high yield is provided.

The photomask base of the present invention is a transparent substrate on which a light-shielding layer and a reflection reduction layer are laminated. The light-shielding layer is a chromium-based material containing chromium, and the reflection-reduction layer is less chromium and contains oxygen than the light-shielding layer. The chromium oxide material is a multilayer film including a plurality of layers, and the oxygen content on the light-shielding layer side of the reflection reduction layer including the multilayer film is more than the oxygen content on the surface side of the reflection reduction layer. A photomask is manufactured using the photomask substrate. Furthermore, a display device is manufactured using this mask.

Description

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

The present invention relates to a photomask substrate and a photomask, and in particular, to a photomask substrate (a substrate for photomasks) used for manufacturing an FPD (Flat Panel Display, flat panel display) device, and a photomask (rotation) using the photomask substrate. A manufacturing method of a photomask) and a manufacturing method of a display device using the photomask manufactured by the manufacturing method.

In FPD (Flat Panel Display) and other display devices such as LCD (Liquid Crystal Display), high-definition, high-speed display, large screen, and wide viewing angle have developed rapidly. One of the elements required for this high-definition and high-speed display is the production of electronic circuit patterns such as fine elements and wiring with high dimensional accuracy. For the patterning of electronic circuits for display devices, a photolithography method is often used. Therefore, a photomask for manufacturing a display device having a fine and highly accurate pattern is required.

For a mask for manufacturing a display device, from the viewpoints of increasing the fineness of a pattern to be used and the drawing processing amount of the mask pattern, generally, the mask pattern is drawn using laser light having a wavelength of 413 nm or the like. In addition, in order to form a mask pattern with high dimensional accuracy by laser drawing, a mask pattern (light-shielding film pattern) formed on a transparent substrate such as synthetic quartz generally includes a light-shielding film for a mask pattern, and a light-shielding film for the mask pattern. It has a laminated structure of a light-shielding layer and a reflection reducing layer, and the light-shielding layer shields light exposed during manufacturing of a display device (Exposure light used in lithography), the reflection reducing layer has and reduces the reflection of the laser drawing light described above. The reflection reducing layer formed on the light-shielding layer suppresses the reflection of the laser drawing light, thereby forming a mask pattern with high dimensional accuracy.

In order to manufacture such a display device with high yield without pixel or circuit defects, the photomask used must also be one with fewer defects. Defects of photomasks are roughly divided into defects of foreign objects caused by the adhesion of foreign objects or pollutants (pollutants), and defects of the mask pattern including a light-shielding film, but both must have fewer defects. In order to reduce the foreign matter defect or the adhesion of pollutants, it is important to clean the mask during the manufacturing process. Before forming a resist for forming a mask pattern on the mask base which is the original version of the mask, use sulfuric acid or persulfate such as sulfuric acid A chemical solution such as a sulfuric acid-containing cleaning solution or an ozone cleaning solution, such as a hydrogen mixture, is cleaned before the resist is applied (chemical cleaning: chemical cleaning). By using such a cleaning solution containing sulfuric acid or an ozone cleaning solution for pre-resist cleaning, the adhesion of foreign matter or contamination is removed, and the adhesion of the resist is improved especially in ozone cleaning, thereby preventing the resistance of the resist. Etching defects caused by poor peeling of the resist film or insufficient adhesion of the resist due to the penetration of the etching solution into the interface between the resist and the reflection reduction layer.

In order to reduce one of the mask pattern defects, it is necessary to reduce the defects in a series of pattern formation steps of resist drawing, developing, and etching on the mask substrate, and it is also necessary to reduce the defects of the light-shielding film itself.

Such a mask for manufacturing a display device, a mask base as an original plate thereof, and a technique related to a manufacturing method of both are disclosed in Patent Document 1.

[Prior technical literature] [Patent Literature]

[Patent Document 1] Japanese Patent No. 5004283

As described above, in order to prevent foreign matter defects in the manufacturing process of the photomask, An acidic cleaning solution or an ozone cleaning solution is used to clean the resist before coating the photoresist substrate. However, after detailed research, it can be seen that the reflection reduction layer formed on the surface layer of the photomask substrate has an in-plane distribution due to this step. The ground is damaged, and the reflectance of the laser light (hereinafter also referred to as drawing light) for which the mask pattern is drawn is changed in an in-plane distribution. In particular, it can be seen that in the case of using a cleaning solution for ozone to clean the resist before coating the photoresist substrate, the reflectance of the laser light is greatly changed compared to the laser light patterned on the photomask. Here, as described above, It is described that the reflection reducing layer is a layer formed on a light-shielding layer that absorbs and shields light that is exposed when the display device substrate is exposed (hereinafter referred to as light for exposure and is distinguished from the above-mentioned drawing light), and is used to reduce The reflection of laser light in the mask pattern drawing improves the drawing accuracy. If there is reflection, the drawing accuracy is reduced due to the interference of the drawing light and the reflected light, resulting in a decrease in drawing resolution and uneven drawing size (mask pattern size). If the reflectance has an in-plane distribution, the drawing size (mask pattern size) also has an in-plane distribution, so that the accuracy of the mask pattern size decreases.

The above-mentioned pre-coating of the resist on the photomask substrate using a cleaning solution containing sulfuric acid or ozone cleaning is not limited to one time, and it is detected on the surface (the surface of the reflection reduction layer) on which the resist is applied. In the case of foreign matter, wash repeatedly until the foreign matter is removed. When a resist film is defective or a resist pattern formed by drawing or developing is defective, the resist is temporarily removed, and the process is restarted from the resist application (will be This step is called resist rework), but in this case, cleaning with a cleaning solution containing sulfuric acid or an ozone cleaning solution is also performed again before the resist is applied. It can be seen that by such repeated treatment of ozone cleaning before the resist coating, the reflectance change of the reflection reducing layer with respect to the laser drawing light and the in-plane distribution of the reflectance are further increased, thereby greatly reducing the dimensional accuracy of the mask pattern.

As described above, the first object of the present invention is to prevent light from accompanying changes in reflectance and changes in reflectance distribution caused by cleaning before application of a resist using a cleaning solution containing sulfuric acid or an ozone cleaning solution. Decrease in mask pattern dimensional accuracy Higher degree mask pattern.

In addition, as described above, in order to be a mask with few defects, in addition to the resistance of the cleaning solution containing sulfuric acid or the ozone cleaning solution before the resist coating, the defects of the light-shielding film for the mask pattern must also be relatively less. The second problem of the present invention is to obtain a high cleaning resistance before cleaning with a resist containing a cleaning solution containing sulfuric acid or an ozone cleaning solution, and has fewer defects and includes a reflection reducing layer and a light shielding layer. Low defect photomask base and photomask for photomask pattern.

Therefore, an object of the present invention is to provide a photomask that has high cleaning resistance and has fewer defects in the cleaning process before the application of the resist using a cleaning solution containing sulfuric acid or an ozone cleaning solution. A photomask substrate for a patterned light-shielding film, and by using the photomask substrate to fabricate a photomask, a photomask having higher dimensional accuracy and fewer defects is provided. And, a method for manufacturing a high-definition display device with a high yield is provided.

To solve the above problems, the present invention has the following configuration.

(Composition 1)

A photomask substrate, characterized in that it has a transparent substrate including a material that is substantially transparent with respect to light exposed, and has a light-shielding layer on the transparent substrate, a reflection reduction layer on the light-shielding layer, and the light-shielding layer includes Chromium material containing chromium, the reflection reducing layer includes a chromium oxide material containing less chromium and containing oxygen than the light shielding layer, the reflection reducing layer is a laminated film having a plurality of layers, and the oxygen content on the light shielding layer side It is equal to or more than the oxygen content on the surface side of the reflection reduction layer.

(Composition 2)

For example, if the mask base of 1 is configured, the film thickness or oxygen content of the reflection reduction layer is adjusted. At least any one of the wavelengths ranges from 350 nm to 550 nm so that the bottom peak wavelength of the film surface reflectance is minimized.

(Composition 3)

For example, in the photomask base of item 1, at least one of the film thickness or the oxygen content of the reflection reduction layer is adjusted so that the bottom peak wavelength of the film surface reflectance is at a range of 365 nm to 550 nm.

(Composition 4)

For example, if the photomask base of any one of 1 to 3 is configured, the reflection reducing layer has a laminated structure including a high chromium oxide layer and a low chromium oxide layer from the light shielding layer side, and the high chromium oxide layer contains 35 atomic% or more. The oxygen content is less than 65 atomic%, and the low chromium oxide layer contains 10 atomic% or more and 50 atomic% or less of oxygen.

(Composition 5)

In the photomask substrate according to any one of 1 to 4, wherein the reflection reducing layer further contains a chromium oxynitride material containing nitrogen.

(Composition 6)

For example, the reticle substrate of 5 is constituted, wherein the reflection reducing layer contains 2 atomic% or more and 30 atomic% or less of nitrogen.

(Composition 7)

In the photomask substrate according to any one of 1 to 6, wherein the light-shielding layer has a chromium nitride layer, the chromium nitride layer contains more nitrogen on the transparent substrate side than on the reflection reduction layer side.

(Composition 8)

If the photomask base of any one of 1 to 7 is constituted, the composition of each element contained in the light-shielding layer and the reflection reducing layer is continuously inclined.

(Composition 9)

If the photomask base of any one of 1 to 8 is formed, wherein the transparent substrate and the above Between the light-shielding layers, there is a functional film that adjusts at least one of the transmittance or the phase shift amount of the exposed light.

(Composition 10)

For example, the photomask base of any one of 1 to 9 is constituted, wherein the photomask base is an original plate of a photomask for display device manufacturing.

(Composition 11)

A manufacturing method of a photomask, which is characterized by including the steps of manufacturing a photomask using a photomask substrate constituting any one of 1 to 10, forming a resist film on the photomask substrate; Patterning; developing to form a resist pattern on the photomask substrate; and patterning the light-shielding layer and the reflection reducing layer by etching.

(Composition 12)

A method for manufacturing a display device is characterized by including an exposure step. The exposure step is to place a photomask manufactured by the method for forming a photomask of 11 on a photomask stage of an exposure device, and form the photomask on the photomask. The transferred pattern is exposed and transferred to a resist formed on a display device substrate.

The mask base of the present invention is a transparent substrate with a light-shielding layer and a reflection reducing layer laminated on it. The light-shielding layer is a chromium-based material containing chromium. The chromium material is a multilayer film including a plurality of layers, and the oxygen content on the light-shielding layer side of the reflection reduction layer including the multilayer film is more than the oxygen content on the surface side of the reflection reduction layer. With this structure, it is possible to provide a chemical solution, particularly an ozone cleaning solution, which has less change in reflectance compared to a chemical solution used in chemical cleaning, has a high washing resistance, and includes a reflection reducing layer. And the mask substrate for the mask pattern for the mask pattern of the light-shielding layer has a defect that is less than that of the mask substrate. In addition, a photomask pattern is provided by using the photomask substrate to fabricate a photomask. Mask with high dimensional accuracy and low defects. Furthermore, by using the photomask to manufacture a display device, a high-definition display device can be manufactured with a high yield.

1‧‧‧ substrate

2‧‧‧ shading layer

2a‧‧‧Shading layer pattern

3‧‧‧ reflection reduction layer

3a‧‧‧Reflection reduction layer pattern

4‧‧‧resist film

4a‧‧‧resist pattern

5‧‧‧ light-shielding film

5a‧‧‧Shading film pattern

21‧‧‧ Lower light-shielding layer (CrN)

21a‧‧‧ Lower light-shielding layer pattern (CrN pattern)

22‧‧‧ Upper light-shielding layer (CrC)

22a‧‧‧Upper shading layer pattern (CrC pattern)

31‧‧‧ 1st reflection reduction layer (CrCON)

31a‧‧‧1st reflection reduction layer pattern (CrCON pattern)

32‧‧‧Second reflection reduction layer (CrCON)

32a‧‧‧Second reflection reduction layer pattern (CrCON pattern)

100‧‧‧mask base

200‧‧‧Mask

300‧‧‧Sputtering device

301‧‧‧sample

311‧‧‧ bezel

312‧‧‧ bezel

321‧‧‧The first gas inlet

322‧‧‧Second gas introduction port

323‧‧‧The third gas inlet

324‧‧‧4th gas inlet

331‧‧‧The first sputtering target

332‧‧‧Second sputtering target

333‧‧‧3rd sputtering target

334‧‧‧4th sputtering target

BU1‧‧‧The first buffer chamber

BU2‧‧‧Second buffer chamber

BU3‧‧‧The third buffer chamber

LL‧‧‧ moved into the chamber

SP1‧‧‧The first sputtering chamber

SP2‧‧‧Second Sputtering Chamber

SP3‧‧‧The third sputtering chamber

SP4‧‧‧The fourth sputtering chamber

UL‧‧‧ moved out of the chamber

FIG. 1 is a cross-sectional configuration diagram of main parts showing a schematic configuration of a mask base according to a first embodiment of the present invention.

FIG. 2 is a schematic view showing a schematic configuration of a continuous sputtering apparatus that can be used for forming a film on a photomask substrate of the present invention.

3 (a) to (e) are cross-sectional structural views of main parts showing manufacturing steps of a photomask according to Embodiment 2 of the present invention.

FIG. 4 is a characteristic diagram showing element distribution of a film of a mask base in Example 1. FIG.

FIG. 5 is a characteristic diagram showing the spectral characteristics of the reflectance of the mask substrate of Example 1. FIG.

FIG. 6 is a characteristic diagram showing a spectral characteristic of a reflectance of a mask substrate of Comparative Example 2. FIG.

Hereinafter, embodiments of the present invention will be specifically described with reference to the drawings. It should be noted that the following embodiment is an embodiment when the present invention is embodied, and the present invention is not limited to this range. In addition, in the drawings, the same or equivalent parts may be denoted by the same reference numerals, and descriptions thereof may be simplified or omitted.

Embodiment 1.

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

FIG. 1 is a schematic cross-sectional view showing a film configuration of a mask base 100 for manufacturing a display device. The mask base 100 is roughly divided into a substrate 1 which is transparent with respect to the light exposed and a light-shielding film 5 for forming a mask pattern. The light-shielding film 5 includes a light-shielding layer 2 formed on the substrate side, and a reflection reducing layer 3 formed on the light-shielding layer 2.

The light-shielding layer 2 has a function of absorbing and shielding exposed light, and includes a light-shielding layer 21 formed below the substrate 1 and a light-shielding layer 22 formed above the light-shielding layer 21. Of the laminated structure. The lower light-shielding layer 21 and the upper light-shielding layer 22 contain a material containing chromium (Cr), and further, the lower light-shielding layer 21 contains more nitrogen (N) than the upper light-shielding layer 22. For example, the material of the lower light-shielding layer 21 is CrN, and the material of the upper light-shielding layer 22 is CrC. Thereby, a difference in etching rate occurs when the light-shielding layer 2 is wet-etched, thereby preventing chromium from remaining, and the cross-sectional shape after the etching also becomes a good shape close to vertical. In addition, the adhesion of the light-shielding layer 2 to the substrate 1 can be improved to prevent peeling defects of the film. Here, if carbon is added to chromium, the wet etching rate with respect to the chromium etchant is easy to control, which is preferable. In addition, in order to reduce the wet etching rate of chromium by adding carbon or the like to improve wet etching controllability, the variation of the ratio of the additive to chromium is preferably 5 atomic% or less, and more preferably 3 atomic %the following.

Furthermore, in FIG. 1, the lower light-shielding layer 21 and the upper light-shielding layer 22 are depicted as being divided into two films, but they may be layers that change continuously or may be divided into two films. Furthermore, it may be a laminated film of three or more layers. It is important that the light-shielding layer 2 is a laminated film, and the nitrogen content on the substrate 1 side (lower surface side) of the laminated film is higher than the nitrogen content on the reflection reduction layer 3 side (upper surface side).

In addition, if necessary, the lower light-shielding layer 21 is not provided, and only the upper light-shielding layer 22 constitutes the light-shielding layer 2.

The reflection reduction layer 3 has a function of preventing reflection of light drawn by the mask pattern, and includes a first reflection reduction layer 31 including an upper light-shielding layer 22 side, and a second reflection reduction layer 32 formed on the first reflection reduction layer 31. Of the laminated structure. In addition, the reflection reduction layer 3 also has an anti-reflection function with respect to the light exposed when the display device is manufactured. The reflection reduction layer 3 includes a material containing at least chromium and oxygen (O), but the chromium content is less than the chromium content of the light shielding layer 2. The reason is that if the chromium content of the reflection reduction layer 3 is greater than the chromium content of the light-shielding layer 2, the reflectivity of the light drawn or exposed with respect to the mask pattern becomes higher. The oxygen content of the first reflection reduction layer 31 on the light shielding layer 2 side is equal to or higher than the oxygen content of the second reflection reduction layer 32 on the surface side. The reason lies in the following aspects: it is easy to adjust the relationship between the refractive index and the optical constant including the extinction coefficient to make it the best A wavelength region with a small reflectance; the reflection reducing layer 3 becomes a dense film so that film defects can be suppressed; and the cleaning resistance to the ozone cleaning solution is improved. Furthermore, in FIG. 1, the first reflection reduction layer 31 and the second reflection reduction layer 32 are depicted as being divided into two films, but they may be continuously changed layers or divided into two films. Furthermore, it may be a laminated film of three or more layers. It is important that the reflection reduction layer 3 is a laminated film, and the oxygen content of the light shielding layer 2 side (lower surface side) of the laminated film is equal to or higher than the oxygen content of the surface side (upper surface side).

In the reflection reduction layer 3, adjust at least one of the film thickness of the reflection reduction layer 3, that is, the film thickness of the first reflection reduction layer 31 and the second reflection reduction layer 32, or the oxygen content of these layers Alternatively, the minimum value of the reflectance of the light-shielding film 5 is in a range of a wavelength of 350 nm to 550 nm.

In another aspect, in the reflection reduction layer 3, the film thickness of the reflection reduction layer 3, that is, the film thickness of the first reflection reduction layer 31 and the film thickness of the second reflection reduction layer 32, or the content of these layers is adjusted. At least one of the amounts of oxygen is such that the minimum value of the reflectance of the light-shielding film 5 is in a range of a wavelength of 365 nm to 550 nm.

The film thickness can be adjusted by the film formation time, and the oxygen content can be adjusted by the flow rate of the supplied oxygen-containing gas or the like. Thereby, for the laser light used for the mask pattern drawing, the mask pattern drawing can be performed to the extent of the minimum reflectance, and the mask pattern drawing accuracy is improved. That is, it is possible to reduce the CD (Critical Dimension, critical dimension) unevenness of the formed mask pattern. Furthermore, near the minimum value of the reflectance of the film surface, there is less change in the reflectance when the mask substrate is subjected to ozone cleaning. From this viewpoint, the unevenness of the CD of the formed mask pattern can also be reduced. Mask pattern drawing often uses light sources with wavelengths ranging from 350nm to 500nm, such as 355nm, 365nm, 405nm, 413nm, 436nm, and 442nm, or lasers ranging from 365nm to 500nm. Therefore, it is also effective to use light-shielding film The minimum value of the reflectance is in a range of a wavelength of 350 nm to 500 nm or a range of a wavelength of 365 nm to 500 nm.

As a result of detailed research, it can be seen that if the oxygen content of the first reflection reduction layer 31 is 35 atoms % Or more and 65 atomic% or less, and the oxygen content of the second reflection reduction layer 32 is 10 atomic% or more and 50 atomic% or less, the adjustment of the wavelength region which becomes the minimum reflectance as described above, the suppression of film defects, And ozone detergency is particularly effective. Conversely, if the content of oxygen is outside the above-mentioned range, the ease of adjustment of the wavelength region that becomes the minimum reflectance is impaired, and the reflectance becomes high.

In addition, if the reflection reducing layer 3 is a chromium oxynitride material further containing nitrogen, the minimum value of the reflectance can be reduced by using the relationship between the refractive index and the optical constant including the extinction coefficient, and therefore, the nitrogen content is ideal. It is 2 atomic% or more and 30 atomic% or less.

In addition, if the reflection reducing layer 3 is a chromium oxycarbonitride material further containing carbon, the washing resistance or the stability over time is improved, and the controllability of wet etching when forming a mask pattern is also improved. The carbon content is preferably 0.5 atomic% or more and 3.0 atomic% or less.

In addition, if each element contained in the light-shielding layer 2 and the reflection reducing layer 3 continuously forms a composition distribution (composition tilt) in the film thickness direction, the cross-section of the light-shielding film pattern after wet etching becomes smooth, so it is preferable , CD accuracy is also improved.

The light-shielding film 5 for forming a mask pattern may be a light-shielding film for a binary mask, or may be formed on a phase shift mask (for example, a halftone phase shift mask (Attenuated Phase Shift Mask) Mask)), or phase shifting film for Levenson Mask (Alternating Phase Shift Mask)), or Multi-level Gradation Mask The light-shielding film 5 above or below the transmittance control film.

For a halftone type phase shift mask in a phase shift mask, or a multi-step light mask with a transmittance control film pattern formed between a transparent substrate and a light-shielding film pattern, the phase shift of the mask pattern becomes A transfer film or a transmittance control film is a function film provided between the substrate 1 and the lower light-shielding layer 21 to adjust at least one of transmittance and phase to perform transmittance control and / or phase control of transmitted light. The functional film is preferably a material obtained by including at least any one of metal, oxygen, nitrogen, carbon, or fluorine in silicon (Si), which is a material that has an etching selectivity to a chromium material, which is a material constituting a light-shielding layer. . For example, metal silicide such as MoSi, metal silicide oxide, metal silicide nitride, metal silicide oxynitride, metal silicide carbon nitride, metal silicide carbon oxide, metal silicide Carbonitrides, SiO, SiO ₂ , and SiON. In the case where the substrate 1 is synthetic quartz, although SiO or SiO ₂ contains the same elements as the substrate, the etching rate is different from the etching rate of the substrate due to the difference in the bonding state between atoms, etc., so that the etching rate can be accurately determined Optical distance (etching depth) control which is important for phase difference control is performed. In addition, the functional film may be a laminated film including the above-mentioned films listed as the functional film.

This functional film is processed by using a light-shielding film pattern 5a containing chromium as an etching mask. Therefore, the functional film is processed using a wet etching solution having a faster etching rate of the functional film than the light-shielding film 5 including the light-shielding layer 2 and the reflection reducing layer 3. Examples of such a wet etching solution include at least one fluorinated compound selected from hydrofluoric acid, hydrosilicofluoric acid, and ammonium hydrogen fluoride, and at least one oxidant selected from hydrogen peroxide, nitric acid, and sulfuric acid, Or a solution containing water. Specific examples thereof include an etching solution obtained by diluting a mixed solution of ammonium hydrogen fluoride and hydrogen peroxide with pure water, or an etching solution obtained by mixing ammonium fluoride in an aqueous hydrofluoric acid solution.

Hereinafter, the manufacturing steps of the photomask substrate will be described in detail.

1. Preparation steps

First, the substrate 1 is prepared.

The material of the substrate 1 is transparent to the light used for the exposure, and is not particularly limited as long as it is a rigid material. Examples include synthetic quartz glass, soda lime glass, and alkali-free glass. Moreover, in order to become a flat and smooth main surface, as needed, grinding | polishing including a rough grinding process process, a precision grinding process process, a partial process process, and a contact grinding process process is performed suitably. Thereafter, the foreign matter or contamination on the surface of the substrate 1 is removed by cleaning. For cleaning, for example, sulfuric acid, sulfuric acid hydrogen peroxide mixture (SPM), ammonia water, ammonia water hydrogen peroxide mixture (APM), OH radical cleaning water, and ozone can be used. Water etc.

2. Light-shielding film forming step

Next, a light-shielding film 5 for forming a mask pattern including a chromium-based material is formed on the main surface of the substrate 1 by a sputtering method. The light-shielding film 5 includes a laminated film having a light-shielding layer 2 and a reflection reduction layer 3. Further, each of the light-shielding layer 2 and the reflection reduction layer 3 also becomes a multilayer film. The number of laminated layers of each laminated film is not particularly limited. Here, the light-shielding layer 2 includes two layers and the reflection reducing layer 3 also includes two layers, including a lower light-shielding layer 21, an upper light-shielding layer 22, and a first reflection-reducing layer 31. The formation steps in the case of a total of four layers and the second reflection reduction layer 32 will be described in detail as an example.

First, a film forming apparatus will be described.

FIG. 2 is a schematic view showing an example of a sputtering apparatus for forming the light-shielding layer 2 and the reflection reducing layer 3.

The sputtering apparatus 300 shown in FIG. 2 is a continuous type and includes the following nine chambers: a carry-in chamber LL, a first sputtering chamber SP1, a first buffer chamber BU1, a second sputtering chamber SP2, a first 2 buffer chamber BU2, third sputtering chamber SP3, third buffer chamber BU3, fourth sputtering chamber SP4, and carry-out chamber UL. The nine chambers are sequentially and sequentially arranged.

The sample 301 with the substrate 1 mounted on the tray can be sequentially transferred to the loading chamber LL, the first sputtering chamber SP1, the first buffer chamber BU1, and the first at a specific moving speed (transfer speed) in the direction of the arrow. 2 sputtering chamber SP2, second buffer chamber BU2, third sputtering chamber SP3, third buffer chamber BU3, fourth sputtering chamber SP4, and carry-out chamber UL.

The carry-in chamber LL is separated from the first sputtering chamber SP1, the fourth sputtering chamber SP4, and the carry-out chamber UL by baffles 311 and 312, respectively. The carry-in chamber LL, the sputtering chambers SP1 to SP4, the buffer chambers BU1 to 3, and the carry-out chamber UL are connected to an exhaust device (not shown) for exhausting air. Furthermore, sputtering targets 331 to 334 and gas introduction ports 321 to 324 are arranged in each of the sputtering chambers SP1 to SP4.

Next, a film formed by using the continuous sputtering apparatus 300 is a lower light-shielding layer 21, The steps of the upper light-shielding layer 22, the first reflection reduction layer 31, and the second reflection reduction layer 32 will be described.

First, a sample 301 with a substrate 1 mounted on a tray (not shown) is carried into the carry-in chamber LL.

After the inside of the sputtering device 300 is formed to a specific degree of vacuum, a specific flow rate of a film-forming gas required to form the lower-layer light-shielding layer 21 is introduced from the first gas introduction port 321, and a specific sputtering power is applied. The sample 301 was passed through the first sputtering target 331 at a specific speed S1. As the first sputtering target, chromium or a target mainly containing chromium was used. As a target mainly containing chromium, there are chromium nitride and the like, but since reactive composition sputtering using a supply gas is easy to tilt control the composition distribution as expected, chromium is used for the target here. In order to form a CrN layer as the lower light-shielding layer 21, a gas system supplied from the first gas introduction port 321 contains at least nitrogen (N) gas, and an inert gas such as argon (Ar) gas may be added as necessary. As the inert gas, in addition to argon, there are helium (He) gas, neon (Ne) gas, krypton (Kr) gas, and xenon (Xe) gas, and one or more kinds can be selected from these if necessary. . The composition distribution in the film thickness direction can be controlled by the arrangement of a gas introduction port, a gas supply method, and the like.

By the above steps, when the sample 301 passes near the first sputtering target 331 of the first sputtering chamber SP1, a chromium-containing film containing a specific film thickness is formed on the main surface of the substrate 1 by reactive sputtering. The material is a light-shielding layer 21 (CrN layer).

After that, the sample 301 passes through the first buffer chamber BU1 and moves to the second sputtering chamber SP2. A film-forming gas required for forming the upper light-shielding layer 22 at a specific flow rate is introduced from the second gas introduction port 322, and a specific sputtering power is applied. In this state, the sample 301 was passed through the second sputtering target 332 at a specific speed S2 while being formed into a film. As the second sputtering target, a chromium target was used. In addition, a target containing an appropriate additive in chromium can also be used. In order to form the CrC layer as the upper light-shielding layer 22, the gas system supplied from the second gas introduction port 322 contains at least a carbon (C) gas, and if necessary, an inert gas such as argon (Ar) gas may be added. As the inert gas, in addition to argon, there are helium (He) gas, neon (Ne) gas, krypton (Kr) gas, and xenon (Xe) gas, and one or more kinds can be selected from these if necessary . Examples of the carbon-containing gas include methane (CH ₄ ) gas, carbon dioxide (CO ₂ ) gas, and carbon monoxide (CO) gas. The composition distribution in the film thickness direction can be controlled by the arrangement of the gas inlet, the gas supply method, and the like.

Through the above steps, when the sample 301 passes near the second sputtering target 332 of the second sputtering chamber SP2, a specific film thickness containing chromium is formed on the main surface of the sample 301 by reactive sputtering. A light-shielding layer 22 (CrC layer) is formed on the base material.

Thereafter, the sample 301 moves to the third sputtering chamber SP3 through the second buffer chamber BU2. A film-forming gas required for forming the first reflection reduction layer 31 at a specific flow rate is introduced from the third gas introduction port 323, and a specific sputtering power is applied. In this state, the sample 301 is passed through the third sputtering target 333 at a specific speed S3, and a film is formed. As the third sputtering target, a chromium target was used. In addition, a target containing an appropriate additive in chromium can also be used. In order to form the CrCON layer as the first reflection reduction layer 31, the gas system supplied from the third gas introduction port 323 includes at least carbon (C), oxygen (O), and nitrogen (N) gases, and argon (Ar ) Gas and other inert gases. As the inert gas, in addition to argon, there are helium (He) gas, neon (Ne) gas, krypton (Kr) gas, and xenon (Xe) gas, and one or more kinds can be selected from these if necessary. . Examples of the carbon-containing gas include methane (CH ₄ ) gas, carbon dioxide (CO ₂ ) gas, and carbon monoxide (CO) gas. Examples of the nitrogen-containing gas include nitrogen (N ₂ ) gas, nitrogen dioxide (NO ₂ ) gas, and nitrogen monoxide (NO) gas. Examples of the oxygen-containing gas include an oxygen (O ₂ ) gas or a carbon dioxide (CO ₂ ) gas, a carbon monoxide (CO) gas, a nitrogen dioxide (NO ₂ ) gas, and an oxide of the oxygen-containing gas. Nitrogen (NO) gas and the like. The composition distribution in the film thickness direction can be controlled by the arrangement of the gas inlet, the gas supply method, and the like. Here, if the film is formed under the condition that the flow rate of oxygen is reduced and the sputtering power is small, it will become a dense film, and film defects will not easily occur.

The sputtering power condition for making the first reflection reduction layer 31 a dense film and less likely to cause film defects is preferably 3.0 kW or less. If you consider the reduction of membrane defects and productivity, It is more preferable that the sputtering power is preferably 1.0 kW to 3.0 kW, and more preferably 1.0 kW to 2.5 kW.

Through the above steps, when the sample 301 passes near the third sputtering target 333 of the third sputtering chamber SP3, a film is formed on the main surface of the sample 301 to a specific thickness by reactive sputtering. The first reflection reduction layer 31 (CrCON layer) of a chromium-based material.

After that, the sample 301 moves to the fourth sputtering chamber SP4 through the third buffer chamber BU3. A film-forming gas required for forming the second reflection reduction layer 32 at a specific flow rate is introduced from the fourth gas introduction port 324, and a specific sputtering power is applied. In this state, the sample 301 was passed through the fourth sputtering target 334 at a specific speed S4 while being formed into a film. As the fourth sputtering target, a chromium target was used. In addition, a target containing an appropriate additive in chromium can also be used. In order to form the CrCON layer as the second reflection reduction layer 32, the gas system supplied from the fourth gas introduction port 324 contains at least carbon (C), oxygen (O), and nitrogen (N) gases, and argon (Ar ) Gas and other inert gases. As the inert gas, in addition to argon, there are helium (He) gas, neon (Ne) gas, krypton (Kr) gas, and xenon (Xe) gas, and one or more kinds can be selected from these if necessary. . Examples of the carbon-containing gas include methane (CH ₄ ) gas, carbon dioxide (CO ₂ ) gas, and carbon monoxide (CO) gas. Examples of the nitrogen-containing gas include nitrogen (N ₂ ) gas, nitrogen dioxide (NO ₂ ) gas, and nitrogen monoxide (NO) gas. Examples of the oxygen-containing gas include an oxygen (O ₂ ) gas or a carbon dioxide (CO ₂ ) gas, a carbon monoxide (CO) gas, a nitrogen dioxide (NO ₂ ) gas, and an oxide of the oxygen-containing gas. Nitrogen (NO) gas and the like. The composition distribution in the film thickness direction can be controlled by the arrangement of the gas inlet, the gas supply method, and the like. Here, if the film is formed under the condition that the flow rate of oxygen is reduced and the sputtering power is small, it will become a dense film, and film defects will not easily occur.

The sputtering power condition for making the second reflection reduction layer 32 a dense film and less likely to cause film defects is preferably 3.0 kW or less. Considering the reduction in film defects and productivity, it is more preferable to set the sputtering power to be 1.0 kW or more and 3.0 kW, and more preferably set to 1.0 kW or more and 2.5 kW or less.

Through the above steps, when the sample 301 passes near the fourth sputtering target 334 of the fourth sputtering chamber SP4, a film is formed on the main surface of the sample 301 by reactive sputtering to include a specific film thickness. The second reflection reduction layer 32 (CrCON layer) of a chromium-based material.

Thereafter, the sample 301 is moved to the carry-out chamber UL, and thereafter, the baffle 312 is closed and vacuum exhausted, and then opened to the atmosphere to take out the sample 301 to the outside of the sputtering apparatus 300.

The removed sample 301 may be inspected or cleaned appropriately as necessary to manufacture the photomask base 100.

The photomask base 100 manufactured in Embodiment 1 has a low reflectance with respect to the light drawn by the photomask pattern and a high resistance to ozone cleaning, that is, cleaning before resist coating, and therefore, even in ozone cleaning After that, it also has a uniform reflectance in the base surface of the photomask. In addition, the light-shielding film 5 for a photomask pattern has a feature that there are fewer film defects.

Embodiment 2.

In the second embodiment, a manufacturing method of a mask for manufacturing a display device will be described with reference to FIG. 3 which shows manufacturing steps in a cross-sectional view of a main part.

First, before coating and preparing a resist on the prepared photomask substrate 100, the above-mentioned cleaning solution containing sulfuric acid or ozone cleaning solution is used for cleaning before resist coating (chemical cleaning: Chemical Cleaning ). In particular, as the pre-resist cleaning, ozone cleaning can be performed using an ozone cleaning solution. The ozone cleaning is to remove the foreign matter and pollution on the resist coating surface through the positioning before the resist coating after the cleaning, and also helps to improve the resistance between the resist and the surface of the photomask substrate. Tightness. This improved adhesion also has the effects of preventing peeling of the resist pattern and preventing deterioration of the etched shape of the light-shielding film 5 for a mask pattern. That is, by improving the adhesiveness, when the light-shielding film 5 for a mask pattern is wet-etched, it is possible to prevent the wet etching solution from penetrating into the interface between the resist film 4 and the mask base (reflection reducing layer 3). The etching shape of the light-shielding film 5 for a mask pattern is prevented from being deteriorated. Hereinafter, ozone cleaning will be described as a pre-resist cleaning. However, as a cleaning device or a cleaning method, it can be replaced with a chemical solution cleaning using a chemical solution such as a cleaning solution containing sulfuric acid (Chemical Cleaning).

The representative ozone cleaning is rotary cleaning using ozone water, but bath cleaning may also be performed. The bath cleaning is performed by placing the photomask base 100 into a bath of an ozone cleaning solution (ozone water). Rotary cleaning has the following characteristics: it is suitable for single-chip processing, the consumption of cleaning liquid is small, and the cleaning device is relatively small, and bath cleaning has the characteristics that it can clean multiple photomask substrates 100 at the same time. The photomask base for large display device manufacturing is also large, so for the photomask base for large display device manufacturing, in terms of the consumption of cleaning liquid and the compactness of the cleaning device, single-chip processing can be preferably used. Cleaning method, especially rotary cleaning method.

In the ozone cleaning by the rotary cleaning method, first, an ozone cleaning solution is dropped near the center of rotation of the mask substrate 100 rotating at a low speed, and the ozone cleaning solution is coated on the mask substrate 100 by spreading by rotation. The entire surface of the second reflection reduction layer 32. Thereafter, while continuously supplying the ozone cleaning liquid, the photomask base 100 was rotated at a low speed to continue cleaning until the cleaning end time. After the cleaning time was completed, pure water was supplied and the ozone cleaning liquid was replaced with pure water. Finally, Spin dry. Furthermore, the immersion type ozone cleaning may be used. After the entire surface of the second reflection reduction layer 32 of the mask substrate 100 is coated with the ozone cleaning solution, the dropping of the ozone cleaning solution and the rotation of the mask substrate are stopped. While rotating at a low speed, the flow-type rotary cleaning method which continuously flows the cleaning liquid has the following characteristics: the ozone concentration is not easy to change, and it also has the mechanical cleaning effect of the flowing liquid. The immersion type cleaning method has less consumption of ozone cleaning liquid. Characteristics. Although the rotary cleaning method has the above-mentioned characteristics, since the ozone cleaning liquid is dropped on the rotation center portion of the mask substrate 100 at first, it is susceptible to a concentric circular cleaning impact (cleaning damage) centered on the rotation center portion. For this reason, it is easy to cause contamination inferior cleaning damage. In most cases, a mask substrate for manufacturing a display device uses a mask substrate having a size of, for example, 1220 mm × 1400 mm, and the concentric circular shape has a large cleaning damage difference (poor distribution in the damage surface). Therefore, especially for a photomask substrate for manufacturing a display device, it is necessary to improve ozone detergency. Furthermore, if the ozone cleaning liquid is dropped after the pretreatment of supplying the pure water to the surface of the photomask substrate 100 to make the surface wet, the initial damage to the surface of the photomask substrate caused by the dripping of the ozone cleaning liquid can be reduced. Damage (initial shock).

After the pre-coating of the resist by ozone cleaning, a resist pattern forming step of forming a resist pattern 4 a on the second reflection reduction layer 32 of the photomask base 100 is performed.

In detail, in this resist pattern forming step, first, a resist film 4 is formed on the second reflection reduction layer 32 which is the outermost layer of the mask base 100 (FIG. 3 (b)). Thereafter, a desired pattern such as a circuit or a pixel pattern is drawn on the resist film 4 using light. As the drawing light, light having a wavelength of 355 nm, 365 nm, 405 nm, 413 nm, 436 nm, and 442 nm, and particularly laser light are often used. Thereafter, the resist film 4 is developed with a specific developing solution to form a resist pattern 4a (FIG. 3 (c)).

Next, using the resist pattern 4a as a mask, the light-shielding film 5 for a mask pattern is wet-etched to form a light-shielding film pattern 5a (FIG. 3 (d)). The light-shielding film 5 for a mask pattern includes a lower light-shielding layer 21, an upper light-shielding layer 22, a first reflection reduction layer 31, and a second reflection reduction layer 32. However, in order to reduce the number of steps, it is preferable to perform wet etching in combination. The reduction in the number of steps is not only beneficial for increasing the throughput or simplifying the etching apparatus, but also generally contributes to improving the quality of defects. Regarding the photomask base 100 manufactured in the first embodiment, all the layers constituting the photomask pattern 5 for the photomask pattern from the lower light-shielding layer 21 to the second reflection reducing layer 32 include a material containing chromium, and are on the surface. The composition of the material of the chromium etching solution is adjusted in the film thickness direction from the side toward the substrate 1 side to accelerate the etching speed, so even if it is a wet etching, the cross section of the main body is vertical, which is not easy to cause tailing at the bottom of the pattern. Also, it is difficult to produce chromium etching residues. Specific examples of the chromium etching solution used herein include an etching solution containing cerium ammonium nitrate and perchloric acid, or an alkaline solution not containing cerium.

After that, the resist pattern 4a is removed by a resist stripping solution, ashing, or the like, and then washed. As the cleaning liquid, for example, sulfuric acid, sulfuric acid hydrogen peroxide mixture (SPM), ammonia water, ammonia water hydrogen peroxide mixture (APM), OH radical cleaning water, ozone water, and the like can be used. Of Then, if necessary, perform mask pattern defect inspection or defect correction. In this way, a photomask 200 having a light-shielding film pattern 5a including a lower light-shielding layer pattern 21a, an upper light-shielding layer pattern 22a, a first reflection reducing layer pattern 31a, and a second reflection reducing layer pattern 32a is formed on the substrate 1.

In the method for manufacturing the photomask 200 described above, the resist film 4 is directly formed on the second reflection reduction layer 32. However, a photomask for etching may be used. In this case, an etching mask is formed on the second reflection reduction layer 32, and a resist film 4 is formed on the etching mask. In the above method, after the resist pattern 4a is formed, the etching mask is temporarily processed by wet etching, and the processed etching mask is used as a mask, and the light shielding layer including the lower light-shielding layer 21 and the upper light-shielding layer is used. 22. The light-shielding film 5 of the first reflection reduction layer 31 and the second reflection reduction layer 32 is wet-etched. Thereafter, the processed etching mask is removed. The resist pattern 4 a may be removed immediately after the etching mask is processed, or may be removed after the wet etching of the light-shielding film 5. In the case where the etching mask is a material having high resistance to wet etching and high adhesion to chromium oxide to prevent penetration of wet etching solution, a vertical cross section including the upper surface portion can be obtained by this method Shaped light-shielding film pattern 5a. Examples of the material of the etching mask include materials containing at least one of metal, oxygen, nitrogen, or carbon in silicon, such as MoSi, SiO, SiON, SiC, and the like.

In the case where the photomask substrate is the phase shift photomask substrate or the multi-level photomask substrate described above, after the light-shielding film pattern 5a is formed by using the above method, the implementation is performed between the substrate 1 and the lower light-shielding layer 21. The functional film for controlling the phase and / or transmittance of the exposed light according to the aspect 1 is etched. Further, when fine adjustment of the phase is required, the substrate 1 is etched to a desired depth using an aqueous hydrofluoric acid solution or an etching solution in which a buffer solution such as ammonium fluoride is mixed with the aqueous hydrofluoric acid solution. Thereafter, the resist pattern 4a is removed, and a phase shift mask is manufactured.

The photomask 200 manufactured in the second embodiment has high resistance to cleaning before the application of the resist, that is, ozone cleaning. Therefore, there is less change in the reflectance of the light depicted relative to the mask pattern. The reflectivity with respect to the light in the mask base surface is the same. As a result, the unevenness of the CD of the formed mask pattern is small. In addition, the cross-sectional shape of the main body portion of the mask pattern is close to vertical, and there are fewer tails at the bottom. In addition, the light-shielding film 5 for a photomask pattern has the characteristics of fewer film defects and fewer defects in the photomask manufacturing step.

Embodiment 3.

In the third embodiment, a method for manufacturing a display device will be described.

In the method for manufacturing a display device according to the third embodiment, first, a substrate with a resist film formed with a resist film on the substrate of the display device will be manufactured by the display device described in the second embodiment. The photomask 200 obtained by the manufacturing method of the photomask is disposed opposite to the resist film formed on the substrate through the projection optical system of the exposure device, and is placed on the photomask stage of the exposure device.

Next, a resist exposure step is performed in which the photoresist 200 is irradiated with the exposed light to expose the resist film.

For exposure light, for example, light in a wavelength range of 365 nm to 550 nm is used, specifically, light of a single wavelength such as i-rays having a wavelength of 365 nm, h-rays having a wavelength of 405 nm, and g-rays having a wavelength of 436 nm, or a composite light including these. .

According to the method for manufacturing a display device according to the third embodiment, the display device is manufactured using the photomask obtained by the method for manufacturing a photomask for manufacturing a display device described in the second embodiment. Therefore, a fine pattern can be formed with high accuracy and low defects. In addition to this lithography step (exposure and development steps), various steps, such as etching a processed film, forming an insulating film, a conductive film, introducing a dopant, or annealing, can be used to form a desired product at a high yield. High-definition display device for electronic circuits.

[Example]

Hereinafter, the present invention will be described in more detail with reference to the drawings with reference to the respective embodiments. Moreover, the same reference numerals are used for the same constituent elements in each embodiment, and the description is simplified or omitted.

[Example 1]

Fig. 3 is also used for explanation in the second embodiment, and is a schematic cross-sectional view of a main part showing a step of manufacturing a mask for display device manufacture from a mask substrate 100 for display device manufacture.

As shown in FIG. 3 (a), the photomask base 100 of Example 1 has: a substrate 1; a light-shielding layer 2 having a function of mainly shielding light used for display device manufacturing exposure; and a reflection reducing layer 3 which reduces The mask pattern depicts the reflection of light; and the light-shielding layer 2 and the reflection reduction layer 3 are combined to form a light-shielding film 5 for a mask pattern. The light-shielding layer 2 includes a two-layer film with CrN as the lower light-shielding layer 21 and CrC as the upper-layer light-shielding layer 22. The reflection reduction layer 3 includes two films. The two-layer film includes: the first CrCON layer 31 (the first reflection Reducing layer), which has a higher oxygen content; and the second CrCON layer 32 (second reflection reducing layer), which contains a material having a lower or equal oxygen content than the material of the first CrCON layer 31. First, the manufacturing method and the film configuration of the photomask base 100 will be described in detail.

((Mask Substrate, Its Manufacturing and Characteristic Evaluation))

(((Substrate)))

A synthetic quartz glass substrate of 8092 size (about 800 mm × 920 mm) having both surfaces of the first main surface and the second main surface polished was prepared and set as the substrate 1. Here, the film thickness is 10 mm, and 8 mm may be used. In order to become a flat and smooth main surface, grinding including a rough grinding process step, a precision grinding process step, a partial machining step, and a contact grinding process step is appropriately performed.

(((Light-shielding film)))

A large-scale continuous sputtering device is used to form a light-shielding film 5 for a mask pattern including a light-shielding layer 2 and a reflection reduction layer 3 on a substrate 1. The light-shielding layer 2 includes CrN as the lower-layer light-shielding layer 21 and As a two-layer film of the upper light-shielding layer 22, the reflection reducing layer 3 includes: a first CrCON layer 31, which has a high oxygen content; and a second CrCON layer 32, which contains a material compared with the material of the first CrCON layer 31 Materials with less or equal oxygen content.

Next, a method for forming such films will be described.

First, the sample 301 mounted on a tray (not shown) with the main surface (the surface on which the light-shielding film is formed) of the substrate 1 facing downward is transferred to a transfer chamber of the continuous sputtering apparatus 300 shown in FIG. 2. LL. Here, a sputtering target 331 including chromium (Cr) is disposed in each of the first sputtering chamber SP1, the second sputtering chamber SP2, the third sputtering chamber SP3, and the fourth sputtering chamber SP4. , 332, 333 and 334.

Next, the baffle 311 is opened, and the sample 301 composed of the substrate 1 is moved from the carrying chamber LL to the first sputtering chamber SP1, and is disposed near the first sputtering target 331 in the first sputtering chamber SP1. The first gas introduction port 321 introduces a mixed gas of argon (Ar) gas and nitrogen (N2) gas, and applies a sputtering power of 1.5 kW to the first sputtering target 331 to perform reactive sputtering. The flow rate of the gas is 65 sccm for Ar and 15 sccm for N ₂ . At this time, the sample 301 was moved in the first sputtering chamber SP1 at a speed of 400 mm / min. Through this step, a film having a thickness of 15 nm was formed on the main surface of the substrate 1 as the CrN film as the lower light-shielding layer 21.

Next, a second gas introduction port 322 arranged near the second sputtering target 332 of the second sputtering chamber SP2 is introduced into a mixed gas in which 4.9% methane (CH ₄ ) is mixed in an argon (Ar) gas, and A sputtering power of 8.5 kW was applied to the second sputtering target 332. The sample 301 was moved from the first sputtering chamber SP1 through the first buffer chamber BU1 to the second sputtering chamber SP2, and reactive sputtering was performed in the second sputtering chamber SP2. Here, the gas flow rate is 31 sccm. At this time, the sample 301 was moved in the second sputtering chamber SP2 at a speed of 400 mm / min. Through this step, a film formed on CrN having a film thickness of 15 nm as the lower-layer light-shielding layer 21 is CrC having a film thickness of 60 nm as the upper-layer light-shielding layer 22.

Next, a third gas introduction port 323 arranged near the third sputtering target 333 of the third sputtering chamber SP3 is introduced into a mixed gas of 5.5% methane (CH ₄ ) and nitrogen mixed in argon (Ar) gas. (N ₂ ) gas and oxygen (O ₂ ) gas, and a sputtering power of 1.5 kW was applied to the third sputtering target 333. The sample 301 was moved from the second sputtering chamber SP2 through the second buffer chamber BU2 to the third sputtering chamber SP3, and reactive sputtering was performed in the third sputtering chamber SP3. The flow rate of the gas was 31 sccm for a mixed gas of argon and methane, 8 sccm for nitrogen, and 3 sccm for oxygen. At this time, the sample 301 was moved in the third sputtering chamber SP3 at a speed of 400 mm / min. By this reactive ion sputtering step, a first CrCON (first reflection reducing layer 31) having a film thickness of 10 nm is formed on CrC having a film thickness of 60 nm as the upper light-shielding layer 22.

Next, a fourth gas introduction port 324 arranged near the fourth sputtering target 334 of the fourth sputtering chamber SP4 is introduced into a mixed gas, nitrogen, 5.5% of methane (CH ₄ ) mixed with argon (Ar), (N ₂ ) gas and oxygen (O ₂ ) gas, and a sputtering power of 1.95 kW was applied to the fourth sputtering target 334. The sample 301 was moved from the third sputtering chamber SP3 through the third buffer chamber BU3 to the fourth sputtering chamber SP4, and reactive sputtering was performed in the fourth sputtering chamber SP4. The flow rate of the gas was 31 sccm for a mixed gas of argon and methane, 8 sccm for nitrogen, and 3 sccm for oxygen. At this time, the sample 301 was moved in the fourth sputtering chamber SP4 at a speed of 400 mm / min. Through this reactive ion sputtering step, a second CrCON (second reflection reduction layer 32) having a film thickness of 19 nm is formed on the first CrCON (first reflection reduction layer 31) having a film thickness of 10 nm.

After that, after moving the sample 301 from the fourth sputtering chamber SP4 to the carry-out chamber UL, the shutter 312 is closed and the vacuum exhaust is temporarily performed to restore the carry-out chamber UL to the atmospheric pressure state. A sample 301 including a light-shielding film 5 including CrN, CrC, the first CrCON, and the second CrCON was formed on the substrate 1 from the substrate side and taken out from the sputtering apparatus 300.

In this manner, a photomask base 100 having a light-shielding film 5 including CrN, CrC, a first CrCON, and a second CrCON formed on a synthetic quartz glass substrate is obtained.

When the film formation conditions of each film (each layer) described above are described using a list, it will be as follows.

Sputtering 1: Ar = 65sccm, N ₂ = 15sccm, Power = 1.5kW, Sample moving speed = 400mm / min

Sputtering 2: Ar / CH ₄ (4.9%) = 31sccm, Power = 8.5kW, specimen moving speed = 400mm / min

Sputtering 3: Ar / CH ₄ (5.5%) = 31sccm, N ₂ = 8sccm, O ₂ = 3sccm, Power = 1.5kW, sample moving speed = 400mm / min

Sputtering 4: Ar / CH ₄ (5.5%) = 31sccm, N ₂ = 8sccm, O ₂ = 3sccm, Power = 1.95kW, sample moving speed = 400mm / min

If it is compared with the following Comparative Example 2, it can be seen that the characteristic content of the film formation conditions is in the sputtering steps 3 and 4 which are the film formation steps of the reflection reduction layer 3, and the oxygen flow rate is low and the power is low. These film formation conditions are the basis for making the reflection reducing layer 3 a dense and less defective film.

With regard to the obtained photomask substrate, a composition analysis in the depth direction was performed by X-ray photoelectron spectroscopy (XPS). The results are shown in FIG. 4. Hereinafter, in the description of this figure, the depth from the surface is expressed by the sputtering time (sputter etching time).

According to the characteristics of the composition distribution, it is divided into a depth of about 8min from the surface (this area is called the surface natural oxide layer), about 8min to about 32min (here this area is called layer A), and about 32min to about 55min (this This area is called layer B here), about 55min to about 70min (this area is called transition layer), about 70min to about 170min (herein this area is called layer C), about 170min to about 195min (here This area is called D layer). The composition between the layers changes continuously. Here, the A layer corresponds to the second CrCON layer (the second reflection reduction layer), the B layer corresponds to the first CrCON layer (the first reflection reduction layer), the C layer corresponds to the CrC layer (the layer above the light-shielding layer), and the D layer Corresponds to the CrN layer (the layer below the light-shielding layer).

The chromium (Cr) atomic ratio of the C layer (CrC layer) is about 90%, and the chromium (Cr) atomic ratio of the D layer (CrN layer) is about 75% or more. In contrast, the chromium (Cr) ) The atomic ratio is small, about 55% or less. That is, the chromium content of the first and second reflection reduction layers 3 is less than the chromium content of the light shielding layer 2. The second reflection reduction layer 32 (the reflection reduction layer on the surface layer side), that is, the oxygen atomic ratio of the A layer is about 24% to 45%, and the first reflection reduction layer 31 is about 45% to 50%. (The reflection reducing layer on the light shielding layer side), that is, the oxygen ratio of the B layer is relatively small. When focusing on nitrogen (N), the nitrogen atomic ratio of the second reflection reduction layer 32 (the reflection reduction layer on the surface layer side), that is, the A layer is about 9% to 20%, and about 2% to 9%. 1st reflection reduction The nitrogen ratio of the layer 31 (the reflection reduction layer on the light shielding layer side), that is, the B layer is relatively large. In addition, nitrogen atoms were detected from the A layer to the D layer, and especially in the CrN layer, that is, the D layer, the nitrogen content rate was increased to about 20%. If we try to focus on the light-shielding layer 2, the nitrogen content of the D layer corresponding to the CrN layer (the lower light-shielding layer 21) is higher than the nitrogen content of the C layer corresponding to the CrC layer (the upper-layer light-shielding layer 22). When focusing on the distribution of atomic ratios in the reflection-reducing layers including the A layer and the B layer, chromium, oxygen, and nitrogen are all continuously inclined in each layer.

Furthermore, in the above-mentioned method for manufacturing a photomask base, the films constituting each layer of the light-shielding film 5 are not returned to the atmosphere midway, but are continuously formed in a reduced-pressure vacuum state. The continuous formation in the reduced-pressure vacuum state can reduce the variation in the composition from the outermost surface (including the second reflection reduction layer 32 of CrCON) to the substrate 1.

(((Evaluation of reflectivity and ozone detergency)))

The photomask substrate 100 was subjected to ozone cleaning, and a test evaluation of ozone detergency was performed. In order to perform an accelerated test of ozone detergency, ozone water having an ozone concentration of 45 mg / L was used as an ozone cleaning solution, and four types of samples were prepared without treatment, 30 minutes, 60 minutes, and 120 minutes. , To evaluate the spectral reflectance characteristics of each sample. The results are shown in FIG. 5. The spectral reflectance is measured by a spectrophotometer (SolidSpec-3700 manufactured by Shimadzu Corporation).

As a result, as shown in FIG. 5, the reflectance of the film surface of the light-shielding film 5 for the mask pattern when the ozone treatment is not processed (before the ozone treatment) is depicted by including a light source such as a laser used when manufacturing a mask for a display device. In the drawing wavelength band including the wavelengths (for example, 355 nm, 365 nm, 405 nm, 413 nm, 436 nm, and 442 nm) of 350 nm to 450 nm, it is 11% or less. The wavelength at which the reflectance becomes the smallest is 430 nm, and the reflectance at this time is 7.26%. The reflectance at a wavelength of 436 nm is also 7.3%, which is approximately the same as the minimum value. The reflectance at 413 nm, which is the following drawing wavelength, was 7.49%. These reflectances are sufficiently low and good values for accurately depicting a mask pattern, and are exposures to display devices mainly composed of i-rays with a wavelength of 365 nm, h-rays with a 405 nm, and g-rays with a 436 nm. The light of light is also sufficiently low to reflect.

If the film surface reflectance of the light-shielding film 5 for a mask pattern is high, when the pattern on the mask is exposed through a projection optical system and transferred to a resist formed on a substrate of a display device, the exposure is performed. The light is reflected from the substrate of the display device, and further, the reflected light is reflected again on the surface of the mask, which causes adverse effects such as flashes or ghosts on the transfer due to reflection, diffuse reflection, imaging, etc. in the projection optical system. Here, the term “flash” refers to a person whose contrast of an optical image to be transferred is reduced due to exposure to fog, which causes a reduction in resolution or a reduction in transfer size accuracy. The reflectance of the light-shielding film 5 for the mask pattern of Example 1 with respect to the light of the exposed light is a sufficiently low value that does not cause problems such as flicker or ghosting. Therefore, high-precision exposure of the display device to the substrate can be performed.

Next, the effect of ozone cleaning on the reflectance of the film surface of the light-shielding film 5 for a mask pattern will be described. The ozone cleaning time is lengthened in the manner of 0 minutes, 30 minutes, 60 minutes, and 120 minutes, and the wavelength at which the reflectance of the film is the smallest is shifted to the short wavelength side, and the minimum reflectance is slightly reduced. The wavelengths that minimize the ozone reflectance at 0 minutes, 30 minutes, 60 minutes, and 120 minutes are 430nm, 412nm, 381nm, and 325nm, and the minimum reflectance at this time is 7.26%, 6.8%, 6.4%, and It was 6.1%. In addition, it has a characteristic that the minimum value is shifted to the short wavelength side while the shape of the spectral characteristic curve is substantially maintained before the ozone treatment reaches 60 minutes. The reflectance at a wavelength of 436 nm increases with the ozone treatment time, but has little change until 60 minutes of ozone treatment, and its value is 8.7%, which is a sufficiently low value compared with the ozone treatment without an increase of 1.4%. In addition, the change in reflectance at a drawing wavelength of 413 nm was reduced by 0.41% to 7.08%, which is a lower value.

In addition, sulfuric acid cleaning was performed on other photomask substrates 100, and a test and evaluation of sulfuric acid washing resistance was performed. As a sulfuric acid cleaning solution, a sulfuric acid cleaning solution having a temperature of 100 ° C. and a sulfuric acid concentration of 98% was used to prepare an untreated, 5-minute, 10-minute, and 15-minute sulfuric acid cleaning solution, and the same spectrophotometer as described above was used. Evaluation of spectral reflectance characteristics estimate.

As a result, the reflectance at a wavelength of 436 nm continued to decrease with the sulfuric acid cleaning time, but there was little change until 15 minutes before the sulfuric acid treatment, and its value was reduced by about 0.7% compared with the sulfuric acid untreated. In addition, the change in reflectance at the drawing wavelength of 413 nm was small, and was 1.025%.

((Manufacture of photomask))

Next, the photomask 200 is manufactured using the photomask substrate 100.

First, the prepared photomask substrate 100 is subjected to ozone cleaning using an ozone cleaning solution.

This ozone cleaning is performed as follows. First, the ozone cleaning solution is dropped near the center of rotation of the mask substrate 100 rotating at a low speed, and the entire second reflection reducing layer 32 of the mask substrate 100 is coated with the ozone cleaning solution by the spreading of the rotating coating. surface. After that, while the cleaning liquid is continuously supplied, the photomask base 100 is rotated at a low speed to continue cleaning until the cleaning end time. After the cleaning time is completed, pure water is supplied to replace the ozone cleaning liquid with pure water, and finally the rotation is performed. dry.

At this stage (Fig. 3 (a)), a defect inspection is performed. The defect inspection is performed on an area of 790 mm × 910 mm, and a defect of 10 μm or more is inspected by visually irradiating the film surface with strong light in a dark room. As a result, the number of detected defects of the photomask base 100 is zero.

Next, as shown in FIG. 3 (b), a resist film 4 having a film thickness of 1000 nm is formed on the second CrCON layer 32 of the photomask base 100. Then, a desired pattern such as a circuit pattern is drawn on the resist film 4 using a laser plotter, and then a specific resist pattern 4a is formed by developing and rinsing (FIG. 3 (c)). Here, the wavelength of the drawing light of the laser drawing machine used is 413 nm. After that, the resist pattern 4a is used as a photomask, and a CrN layer (lower light shielding layer 21), a CrC layer (upper light shielding layer 22), and a first CrCON layer are sequentially formed on the substrate 1 by wet etching. The first light-reduction layer 31 and the second CrCON layer (the second reflection-reduction layer 32) are patterned integrally with a total of four light-shielding films 5 to form a light-shielding film pattern 5 a (FIG. 3 (d)). Therefore, the light-shielding film pattern 5a includes a lower-layer light-shielding layer pattern 21a including CrN, Contains a CrC upper light-shielding layer pattern 22a (the above two layers are light-shielding layer patterns 2a), a first reflection reduction layer pattern 31a including a first CrCON, and a second reflection reduction layer pattern 32a including a second CrCON (the two layers are Reflection reduction layer pattern 3a). Here, as the wet etching, a chromium etchant containing cerium ammonium nitrate and perchloric acid was used.

Up to the above steps, the sample produced in the same manner was used, and the cross-sectional shape of the light-shielding film pattern 5a in a state where the resist pattern 4a remained was observed using a scanning electron microscope. As a result, tailing at the bottom was not found, and a light-shielding film pattern 5a having a vertical cross-sectional shape was obtained.

Thereafter, the resist pattern is peeled off (FIG. 3 (e)), and a photomask 200 having a light-shielding film pattern 5 a formed on the synthetic quartz glass substrate 1 is obtained.

The size unevenness (CD unevenness) of the mask pattern of the photomask was measured by SIR8000 manufactured by Seiko Instruments NanoTechnology. The measurement of CD unevenness is performed on a 5 × 5 area of a region of 880 mm × 910 mm other than the peripheral area of the substrate. In the following examples and comparative examples, the measurement of CD unevenness uses the same device and the same evaluation method.

As a result, all the CDs were 0.105 μm. The results of the comparative examples are also described below. The CD unevennesses of Comparative Example 1 and Comparative Example 2 were 0.125 μm and 0.150 μm, respectively, and the CD variations of Example 1 were not good.

((Manufacture of display device))

The photomask 200 produced in the first embodiment is set on a photomask stage of an exposure device, and pattern exposure is performed on a sample having a resist film formed on a substrate of a display device. Then, by developing the exposed resist film, a resist pattern is formed on the display device substrate. As the exposure light, light having a wavelength of 300 nm to 500 nm including an i-ray having a wavelength of 365 nm, an h-ray having a wavelength of 405 nm, and a g-ray having a wavelength of 436 nm is used.

The reticle pattern of the reticle 200 produced in Example 1 has a high dimensional accuracy, which is 0.105 μm in terms of CD unevenness, and the reflectance of the exposed light is also low, and There are also fewer defects at the substrate stage, and the number of defects is zero. Therefore, the transfer pattern of the resist pattern on the display device substrate is also highly accurate and has fewer defects.

This resist pattern is transferred to the film to be processed by etching, and a high-yield process having a desired characteristic can be manufactured at a high yield by various steps such as forming an insulating film, a conductive film, introducing a dopant, or annealing. Fine display device.

[Example 2]

The second embodiment is a photomask in which only the film formation conditions of the sputtering 3 and the sputtering 4 in the embodiment 1 are changed so that the first reflection reduction layer 31, that is, the CrCON layer, and the second reflection reduction layer 32, that is, the CrCON layer, have the same oxygen content. The examples of the substrate are the same as those of the first embodiment except for the method for manufacturing the photomask and the method for manufacturing the display device. Therefore, the structure of the light-shielding film 5 for a mask pattern includes CrN (lower-layer light-shielding layer 21), CrC (upper-layer light-shielding layer 22), first CrCON (first reflection reduction layer 31), and 2 CrCON (the second reflection reduction layer 32) totals 4 layers.

The film forming conditions of Example 2 are shown below.

Sputtering 1: Ar = 65sccm, N ₂ = 15sccm, Power = 1.5kW, Sample moving speed = 400mm / min

Sputtering 2: Ar / CH ₄ (4.9%) = 31sccm, Power = 8.5kW, specimen moving speed = 400mm / min

Sputtering 3: Ar / CH ₄ (5.5%) = 34.8sccm, N ₂ = 32.2sccm, CO ₂ = 4.5sccm, Power = 1.74kW, sample moving speed = 400mm / min

Sputtering 4: Ar / CH ₄ (5.5%) = 34.8sccm, N ₂ = 32.2sccm, CO ₂ = 4.5sccm, Power = 1.74kW, sample moving speed = 400mm / min

Here, although sputtering 3 and sputtering 4 are film formation under the same conditions, they are multilayer films formed by dividing the chamber into a third sputtering chamber SP3 and a fourth sputtering chamber SP4.

In addition, as in Example 1, the characteristic content under the film formation conditions is in the sputtering steps 3 and 4 which are the film formation steps of the reflection reduction layer 3, and the flow rate of the oxygen component is small and the function is small. Film formation was performed under a condition of low rate. This condition becomes the basis for a dense and less defective film.

The photomask substrate manufactured under the film forming conditions was evaluated by the same evaluation method and the same conditions as in Example 1. As a result, the oxygen contents of the first CrCON (the first reflection reduction layer 31) and the second CrCON (the second reflection reduction layer 32) are the same because the film formation conditions are the same. In other words, although the oxygen distribution is present in each layer as in Example 1, the first CrCON and the second CrCON-based films have the same oxygen distribution.

Regarding the reflectance of the film surface of the light-shielding film 5 for a mask pattern without ozone treatment (before ozone treatment), the reflectance at a wavelength of 436 nm is 8.7%, and the reflectance at the following drawing wavelength, that is, 413 nm, is 10.5%. These reflectances are a sufficiently low and good value for accurately depicting a mask pattern, and are exposures to a display device mainly composed of an i-ray with a wavelength of 365 nm, an h-ray with 405 nm, and a g-ray with 436 nm. The light also has a sufficiently low reflectivity.

In addition, the change in the reflectance at a wavelength of 436 nm generated by the ozone treatment for 60 minutes increased by 1.3%, and the change in the reflectance at a wavelength of 413 nm increased by 0.41%, which was sufficiently small. In addition, the amount of change in reflectance at a wavelength of 436 nm caused by sulfuric acid treatment for 15 minutes was reduced by 1.5%, and the amount of change in reflectance at a wavelength of 413 nm was reduced by 1.35%, which were sufficiently small. In addition, the number of defects of 10 μm or more in the mask substrate of Example 2 subjected to the ozone treatment was zero.

In addition, the CD unevenness using the photomask substrate manufactured by the method of Example 2 and the photomask manufactured by the same method as in Example 1 was a sufficiently small CD unevenness of 0.112 μm in the same evaluation as in Example 1. .

As described above, the photomask base manufactured by the method of Example 2 is one in which the change in reflectance with ozone cleaning is small and the ozone cleaning resistance is high, and the defect quality where the number of visual defects is also 0 is also excellent . In addition, a mask manufactured using the mask substrate is a mask pattern with sufficiently small CD unevenness and a high-precision mask pattern. Therefore, a high-definition display device having desired characteristics can be manufactured with a high yield.

[Example 3]

Example 3 is an example of a mask base of a laser plotter having a wavelength of 355 nm for laser (drawing light) used in the manufacture of the mask, divided by the reflectance of the film surface of the light-shielding film 5 for the mask pattern. A photomask substrate was produced in the same manner as in Example 1 except that the film formation conditions of sputtering 3 and sputtering 4 in Example 1 were adjusted so that the minimum value was near the wavelength of 355 nm. The configuration of the light-shielding film 5 for the mask pattern is the same as that in Example 1, and includes CrN (lower-layer light-shielding layer 21), CrC (upper-layer light-shielding layer 22), and first CrCON (first reflection reduction) formed on the substrate in this order. Layer 31) and the second CrCON (second reflection reduction layer 32) total four layers.

The film formation conditions of Example 3 are shown below.

Sputtering 1: Ar = 65sccm, N ₂ = 15sccm, Power = 1.5kW, Sample moving speed = 400mm / min

Sputtering 2: Ar / CH ₄ (4.9%) = 31sccm, Power = 8.5kW, specimen moving speed = 400mm / min

Sputtering 3: Ar / CH ₄ (5.5%) = 34.8sccm, N ₂ = 32.2sccm, CO ₂ = 4.5sccm, Power = 1.45kW, sample moving speed = 400mm / min

Sputtering 4: Ar / CH ₄ (5.5%) = 34.8sccm, N ₂ = 32.2sccm, CO ₂ = 4.5sccm, Power = 1.45kW, sample moving speed = 400mm / min

Here, the difference from the film-forming conditions of Example 2 is that the power of sputtering 3 and 4 is reduced.

The photomask substrate manufactured under the film forming conditions was evaluated by the same evaluation method and the same conditions as in Example 1. As a result, the chromium content, oxygen distribution, and nitrogen distribution of the first CrCON (first reflection reduction layer 31) and the second CrCON (second reflection reduction layer 32) were respectively the same as those of the first CrCON (first The reflection reduction layer 31) and the second CrCON (second reflection reduction layer 32) tend to have the same chromium content, oxygen distribution, and nitrogen distribution. That is, the oxygen content of the first CrCON (first reflection reduction layer 31) is greater than the oxygen content of the second CrCON (second reflection reduction layer 32).

The reflectance of the film surface of the light-shielding film 5 for a mask pattern was measured in the same manner as in Example 1. As a result, the reflectance when the ozone treatment was untreated (when the ozone treatment was not performed) was 11.0% or less in the drawing wavelength range of 350 nm to 450 nm. . The wavelength at which the reflectance becomes the smallest is 360 nm, and the reflectance at this time is 9.0%. The reflectance at a wavelength of 436nm is also 10.0%. The reflectance at 355 nm, which is the following drawing wavelength, was 9.3%. These reflectances are sufficiently low and good values for high-precision mask pattern drawing, and are exposures to display devices mainly composed of i-rays with a wavelength of 365 nm, h-rays with a 405 nm, and g-rays with a 436 nm. The light also has a sufficiently low reflectivity.

In addition, the change in the reflectance at a wavelength of 436 nm generated by the ozone treatment for 60 minutes increased by 1.0%, and the change in the reflectance at a wavelength of 355 nm increased by 1.5%, which was sufficiently small. In addition, the amount of change in the reflectance at a wavelength of 436 nm generated by the sulfuric acid treatment for 15 minutes was reduced by 0.85%, and the amount of change in the reflectance at a wavelength of 413 nm was reduced by 1.5%, which were sufficiently small. The number of defects of 10 μm or more in the mask substrate of Example 3 subjected to the ozone treatment was zero.

In addition, the CD unevenness using the photomask substrate manufactured by the method of Example 3 and the photomask manufactured by the same method as in Example 1 was a sufficiently small CD unevenness of 0.105 μm in the same evaluation as in Example 1. . When manufacturing the photomask, a laser drawing machine with a drawing wavelength of 355 nm was used.

As described above, the photomask base manufactured by the method of Example 3 is the one with less change in reflectance accompanying ozone cleaning and high ozone detergency, and the defect quality with visual defect number of 0 is also excellent . In addition, a mask manufactured using the mask substrate is a mask pattern with sufficiently small CD unevenness and a high-precision mask pattern. Therefore, a high-definition display device having desired characteristics can be manufactured with a high yield.

[Example 4]

The photomask base 100 of Embodiment 4 is a light having a phase shift film formed between the substrate 1 and the light-shielding film 5 for a photomask pattern, which is a function film that adjusts the transmittance and phase shift amount of the exposed light. The mask substrate is a so-called phase shift mask substrate. It should be noted that the light-shielding film 5 for a mask pattern formed on the phase shift film is the same light-shielding film as in Example 1, and description thereof is omitted.

On a substrate 1 including a synthetic quartz glass substrate of the same size as in Example 1, a large-scale continuous sputtering apparatus was used to form a phase shift film including a two-layer film of MoSiN. When the film is formed as a phase shift film, the sputtering targets of the first sputtering chamber SP1 and the second sputtering chamber SP2 are replaced with sputtering targets 331 and 332 containing molybdenum silicide (MoSi), respectively. Film formation of the phase shift film was performed under film formation conditions.

Sputtering 1: Ar = 50sccm, N ₂ = 90sccm, Power = 8.0kW, Sample moving speed = 400mm / min

Sputtering 2: Ar = 50sccm, N ₂ = 90sccm, Power = 8.0kW, sample moving speed = 400mm / min

According to the above film forming conditions, in the sputtering 1, a first phase shift film including a silicon molybdenum nitride film (MoSiN) with a film thickness of 55 nm was formed on the substrate 1, and in the sputtering 2, the film formation was A second phase shift film including a silicon molybdenum nitride film (MoSiN) having a film thickness of 55 nm is formed on the substrate 1 with a phase shift film having a total film thickness of 110 nm including two silicon molybdenum nitride films (MoSiN).

As for the substrate on which the phase shift film was formed, transmittance and phase difference were measured with MPM-100 manufactured by Japan Lasertec Corporation. In the measurement of transmittance and phase difference, a 6025-size dummy substrate fabricated at the same time was used for measurement. As a result, the transmittance was 5.5% (wavelength: 365 nm) and the phase difference was 180 ° (wavelength: 365 nm).

Next, a film of the light-shielding film 5 for a mask pattern similar to that in Example 1 was formed on the phase-shifting film to manufacture a phase-shifting mask base. Furthermore, when the light-shielding film 5 for the mask pattern is formed, the sputtering targets 331 and 332 of the first sputtering chamber SP1 and the second sputtering chamber SP2 are replaced with chromium (Cr), and the phase is shifted. A light-shielding film 5 for a mask pattern is formed on the film.

The obtained phase shift mask substrate was evaluated by the same evaluation method and the same conditions as in Example 1. The chromium content, oxygen distribution, and nitrogen distribution of the light-shielding film 5 for the mask pattern are the same, and the change of the reflectance of the light-shielding film 5 after ozone treatment and sulfuric acid treatment is also Same result.

Next, using this phase shift mask substrate, a phase shift mask is manufactured.

First, in the same manner as in Example 1, the prepared phase shift mask substrate was subjected to ozone cleaning using an ozone cleaning solution.

Next, a resist film 4 having a thickness of 1000 nm is formed on the light-shielding film 5. Next, a desired pattern such as a circuit pattern is drawn on the resist film 4 using a laser plotter, and development and washing are performed to form a specific resist pattern 4a. Thereafter, the resist pattern is used as a photomask, and the light-shielding film 5 is patterned by wet etching using a chromium etchant containing cerium ammonium nitrate and perchloric acid to form a preliminary light-shielding film pattern.

Thereafter, without removing the resist pattern, the resist pattern and the light-shielding film pattern are used as a mask, and hydrogen peroxide, nitric acid, sulfuric acid, and the like are added to fluorine compounds such as hydrofluoric acid, hydrosilicic acid, and ammonium hydrogen fluoride. The etching solution obtained from the oxidant is used to pattern the phase shift film by wet etching to form a phase shift film pattern.

Next, without removing the resist pattern, the preliminary light-shielding film pattern is etched again by the above-mentioned chromium etching solution, and a light-shielding film pattern having a desired pattern line width is formed in the central portion on the phase shift film pattern.

Finally, the resist pattern is peeled off to obtain a phase shift mask having a phase shift film pattern and a light-shielding film pattern formed on the synthetic quartz glass substrate 1.

The dimensional unevenness (CD unevenness) of the phase shift film pattern of the phase shift mask was measured and evaluated in the same manner as in Example 1. As a result, the CD unevenness was 0.088 μm. This phase shift mask is a phase shift film pattern with sufficiently small CD unevenness and high accuracy. Therefore, it is possible to manufacture a high-definition display device having desired characteristics with a high yield rate as in Example 1.

(Comparative example 1)

Comparative Example 1 is an example of manufacturing a photomask base only by exchanging the film formation conditions of sputtering 3 and sputtering 4 of Example 1. In addition, the method includes a photomask manufacturing method and a display device manufacturing method. All the methods are the same as those in the first embodiment. That is, in Comparative Example 1, the sputtering 3 and the sputtering 4 were formed under the conditions of the sputtering 4 and the sputtering 3 in Example 1, respectively, except that the films were formed in the same manner as in Example 1. Therefore, the structure of the light-shielding film 5 for a mask pattern includes CrN (lower-layer light-shielding layer 21), CrC (upper-layer light-shielding layer 22), first CrCON (first reflection reduction layer 31), and 2 CrCON (second reflection reduction layer 32) totals 4 layers, but the first CrCON of Comparative Example 1 becomes the second CrCON of Example 1, and the second CrCON of Comparative Example 1 becomes the first CrCON of Example 1.

The film forming conditions of Comparative Example 1 are shown below.

Sputtering 1: Ar = 65sccm, N ₂ = 15sccm, Power = 1.5kW, Sample moving speed = 400mm / min

Sputtering 2: Ar / CH ₄ (4.9%) = 31sccm, Power = 8.5kW, specimen moving speed = 400mm / min

Sputtering 3: Ar / CH ₄ (5.5%) = 31sccm, N ₂ = 8sccm, O ₂ = 3sccm, Power = 1.95kW, sample moving speed = 400mm / min

Sputtering 4: Ar / CH ₄ (5.5%) = 31sccm, N ₂ = 8sccm, O ₂ = 3sccm, Power = 1.5kW, sample moving speed = 400mm / min

The photomask substrate manufactured under the film forming conditions was evaluated by the same evaluation method and the same conditions as in Example 1. As a result, the chromium content, oxygen distribution, and nitrogen distribution of the first CrCON (first reflection reduction layer 31) and the second CrCON (second reflection reduction layer 32) became the second CrCON (second reflection The chromium content, oxygen distribution, and nitrogen distribution of the reduction layer 32) and the first CrCON (the first reflection reduction layer 31). For example, the oxygen content of the first CrCON (the first reflection reduction layer 31, the lower reflection reduction layer) of Comparative Example 1 does not reach the oxygen content of the second CrCON (the second reflection reduction layer 32, the upper reflection reduction layer). . In addition, the change in reflectance at a wavelength of 436 nm generated by ozone treatment for 60 minutes increased by 1.2%, which is sufficiently small. The reflectance at a wavelength of 436 nm is higher, which is 15% or more, and is used to depict a mask pattern The accuracy of the display device substrate or the accuracy of exposure and transfer is reduced. In addition, ozone treatment The number of defects of 10 μm or more in the mask substrate of Comparative Example 1 was one.

The CD unevenness using the photomask substrate manufactured by the method of Comparative Example 1 and the photomask manufactured by the same method as in Example 1 was 0.125 μm in the same evaluation as in Example 1.

As described above, the photomask base manufactured by the method of Comparative Example 1 has less change in the reflectance with ozone cleaning, but the reflectance itself is high, being 15% or more. Therefore, the CDs of the mask patterns of the masks manufactured using the mask substrate are not all 0.125 μm, which is inferior to that of the first or second embodiment. In addition, the number of defects in the basal stage of the photomask is also one, but more than zero in Embodiment 1 or Embodiment 2. The measurement object has a large defect size of 10 μm, so the difference between one defect number has a large effect on the yield of the display device. Therefore, the yield of the high-definition display device having the required characteristics is inferior to that of Embodiment 1 or Embodiment 2.

(Comparative example 2)

Regarding Comparative Example 2, when a single-layer reflection reducing layer is used, the layer structure of the light-shielding layer 2 formed by CrN (lower light-shielding layer 21) and CrC (upper-light-shielding layer 22) sequentially formed on the substrate 1 and Example 1 is the same. However, the film formation conditions of CrC as the upper light-shielding layer 22 are different from those in the first embodiment. Under the film formation conditions, the same as in Example 1 is only the lower light-shielding layer 21, that is, CrN. Except for this, the method including the evaluation method of the photomask substrate, the photomask manufacturing method, and the display device manufacturing method are all the same as those of the first embodiment. That is, in Comparative Example 2, the film forming conditions of sputtering 2 and sputtering 3 are different from those in Example 1, and sputtering 4 is set to pass the sample 301 through the sputtering chamber SP4 and skip the film forming process. Other than that, it is the same as that of Example 1. The structure of the light-shielding film 5 for a mask pattern includes a total of three layers of CrN (lower-layer light-shielding layer 21), CrC (upper-layer light-shielding layer 22), and CrCON (reflection reducing layer 3) sequentially formed on the substrate 1.

The film forming conditions of Comparative Example 2 are shown below.

Sputtering 1: Ar = 65sccm, N ₂ = 15sccm, Power = 1.5kW, Sample moving speed = 400mm / min

Sputtering 2: Ar / CH ₄ (4.9%) = 31sccm, Power = 8.5kW, specimen moving speed = 400mm / min

Sputtering 3: Ar / CH ₄ (4.9%) = 34.8sccm, N ₂ = 32.2sccm, O ₂ = 5.5sccm, Power = 3.6kW, sample moving speed = 400mm / min

The characteristic content under the film formation condition is as follows: the reflection reduction layer 3 is a single layer film (film formed in a sputtering chamber); in the film formation step, that is, in the sputtering 3, the phase Compared with Example 1 or Example 2, the film formation was performed under the condition that the flow rate of the oxygen component was larger and the power was higher than about 2 times (1.8 to 2.4 times).

The photomask substrate manufactured under the film forming conditions was evaluated by the same evaluation method and the same conditions as in Example 1. As a result, as shown in FIG. 6, the spectral reflectance characteristic curve of the film surface of the light-shielding film 5 for the mask pattern when untreated with ozone and the light-shielding film 5 for the mask pattern when untreated with ozone in Example 1 The spectral reflectance characteristic curve of the film surface is approximately the same, and the laser depicts a wavelength band of 350 nm to 450 nm, which is less than 12%. The wavelength at which the reflectance becomes the smallest is 430 nm, which is the same as in Example 1, and the reflectance at this time is 1.24% higher than that in Example 1, and is 8.5%. The reflectance at a wavelength of 436 nm is also 8.5% and is the same as the minimum value. The reflectance at 413 nm, which is the drawing wavelength, was 8.69%. On the other hand, the spectral reflectance characteristics of the film surface of the light-shielding film 5 for a mask pattern when an ozone cleaning process is performed are different from those of the first embodiment. As the ozone cleaning treatment time increases, the wavelength shifted to the short-wavelength side with the minimum reflectance has the same characteristics as in Example 1. However, the minimum value of the reflectance at this time is opposite to that in Example 1. The processing time increases and becomes higher. Specifically, the wavelengths at which the reflectance at the ozone cleaning time of 0 minutes, 30 minutes, 60 minutes, and 120 minutes are the smallest are 430 nm, 400 nm, 358 nm, and 309 nm, respectively. The minimum reflectance at this time is 8.5%, 10.2 %, 11.7%, and 15.4%. As a result of the spectral reflectance characteristic, the change in reflectance at a wavelength of 436 nm increased by 6.7% by performing ozone treatment for 60 minutes, and the increase in reflectivity at a depicted wavelength of 413 nm was also large, at 4.7%. And reduce the precision of the mask pattern drawing or the precision of exposure and transfer to the display device substrate. In addition, the number of defects of 10 μm or more in the mask substrate of Comparative Example 2 subjected to ozone treatment was 20 or more, and there were many defects.

Using a photomask base manufactured by the method of Comparative Example 2, a photomask was manufactured in the same manner as in Example 1. In addition, using a sample prepared in the same manner as the comparative example, the cross-sectional shape of the light-shielding film pattern 5a in a state where the resist pattern 4a remained was observed using a scanning electron microscope. As a result, a slight smear was found, and the cross-sectional shape of the surface layer part was further lost. In addition, chromium residue was found on the substrate 1. Regarding the unevenness of the CD, the change in the reflectance of the ozone cleaning is large, so it was 0.150 μm in the same evaluation as in Example 1.

As described above, the photomask base manufactured by the method of Comparative Example 2 has a large reflectance accompanied by ozone cleaning, and the number of defects is also 20 or more, and the quality of the defects is also poor. The change in the reflectance of ozone cleaning of a photomask manufactured using the photomask substrate is large, so the CD of the photomask pattern is not all 0.150 μm, which is inferior to that of Example 1 or Example 2. Therefore, the manufacturing yield of a high-definition display device having desired characteristics is low.

Claims (12)

A photomask substrate, comprising: a transparent substrate including a material substantially transparent with respect to light exposed; a light-shielding layer on the transparent substrate; and a reflection reducing layer on the light-shielding layer. The light-shielding layer includes: Chromium material containing chromium, the reflection reducing layer includes a chromium oxide material containing less chromium and containing oxygen than the light shielding layer, the reflection reducing layer is a laminated film having a plurality of layers, and the oxygen content on the light shielding layer side It is equal to or more than the oxygen content on the surface side of the reflection reduction layer. For example, in the photomask substrate of claim 1, at least one of the film thickness or the oxygen content of the reflection reduction layer is adjusted so that the bottom peak wavelength of the film surface reflectance is in a range of 350 nm to 550 nm. For example, the photomask substrate of claim 1, wherein at least any one of the film thickness and the oxygen content of the reflection reduction layer is adjusted so that the bottom peak wavelength of the film surface reflectance is in the range of 365nm to 550nm. The photomask substrate according to any one of claims 1 to 3, wherein the reflection reducing layer has a laminated structure of a high chromium oxide layer and a low chromium oxide layer from the light shielding layer side, and the high chromium oxide layer contains 35 atomic% Above and below 65 atomic% of oxygen, the above low chromium oxide layer contains 10 atomic% or more and 50 atomic% or less of oxygen. The photomask substrate according to any one of claims 1 to 3, wherein the reflection reduction layer further comprises a chromium oxynitride material containing nitrogen. The photomask substrate according to claim 5, wherein the reflection reduction layer contains nitrogen in an amount of 2 atomic% or more and 30 atomic% or less. The photomask substrate according to any one of claims 1 to 3, wherein the light-shielding layer has a chromium nitride layer, and the chromium nitride layer includes more nitrogen on the transparent substrate side than on the reflection reduction layer side. The photomask substrate according to any one of claims 1 to 3, wherein the composition of each element contained in the light-shielding layer and the reflection reducing layer is continuously inclined. The photomask substrate according to any one of claims 1 to 3, wherein a functional film for adjusting at least any one of transmittance or phase shift amount of light exposed between the transparent substrate and the light-shielding layer is provided. The photomask substrate according to any one of claims 1 to 3, wherein the photomask substrate is an original plate of a photomask for display device manufacturing. A manufacturing method of a photomask, which comprises the steps of manufacturing a photomask: using the photomask substrate according to any one of claims 1 to 10, forming a resist film on the photomask substrate; Patterning; developing a resist pattern on the photomask substrate; and patterning the light-shielding layer and the reflection reducing layer by etching. A method for manufacturing a display device is characterized by including an exposure step. The exposure step is to place a photomask manufactured by the method for manufacturing a photomask of claim 11 on a photomask stage of an exposure device, and form the photomask on the photomask. The transfer pattern on the cover is exposed and transferred to a resist formed on the display device substrate.