JP5164088B2 - Mask blank and photomask - Google Patents

Description

  The present invention relates to a mask blank and a photomask.

Conventionally, as a method for manufacturing a mask blank for FPD (flat panel display), after forming a Cr-based light-shielding film on a glass substrate, while discharging a resist solution from a nozzle having a resist solution supply port extending in one direction, A method of forming a resist film by moving a nozzle relative to the light shielding film surface in a direction intersecting the one direction is known (hereinafter referred to as a slit coater). For a photomask for LSI, it has been proposed to use a molybdenum silicide (MoSi) -based material as a light shielding film material that can be patterned by dry etching (see, for example, Patent Document 1). Further, in order to improve the adhesion between the light shielding film and the resist film, it has been proposed to form a metal thin film or an oxidized metal silicide film on the light shielding film (see, for example, Patent Documents 2 and 3). ).
Japanese Examined Patent Publication No. 3-66656 Japanese Patent Laid-Open No. 1-142637 JP-A-3-116147

  In a mask blank (FPD mask blank) for manufacturing an FPD device, a resist film is formed on a light shielding film. This resist film is used as an etching mask when the light shielding film is etched. However, in the mask blank for FPD, the area of the surface of the light shielding film on which the resist film is to be formed is large. Therefore, compared with the mask blank for LSI, for example, the coating unevenness of the resist film and the in-plane film thickness uniformity are deteriorated. Is likely to occur. Further, unlike the manufacture of an LSI that cuts a single wafer into a large number of chips, in the manufacture of an FPD device, the number of devices on which pattern transfer is simultaneously performed by a single photomask is as small as about 1 to several. Therefore, in the case of a mask blank for FPD, if a pattern defect occurs during photomask manufacturing, the influence on the yield is large. Therefore, in the mask blank for FPD, it is particularly desired to form a resist film having no coating unevenness and good in-plane film thickness uniformity.

  Further, when manufacturing a mask blank for FPD, the light shielding film is patterned by wet etching using an etchant, with an emphasis on cost and throughput, for example. In this case, the etching accuracy tends to be lower than when dry etching is performed. Therefore, it is more important that the resist film serving as an etching mask is in a state where there is no coating unevenness and the in-plane film thickness uniformity is good.

  Under such circumstances, the inventor of the present application examined using a metal silicide-based material (specifically, a MoSi-based material) instead of a Cr-based material as a material for a light shielding film of an FPD mask blank. . The light-shielding film formed of a metal silicide material has good adhesion to the substrate, high chemical resistance (acid resistance) when manufacturing a photomask, and less defects due to film peeling from the shield. It has good characteristics in terms of points. Therefore, the metal silicide-based material is a material to be noted as a material for the light shielding film of the mask blank for FPD.

  Here, when manufacturing a mask blank for FPD, the resist film is discharged from, for example, a nozzle having a resist solution supply port extending in one direction in consideration of coating accuracy with respect to the mask blank, yield, and the like. The nozzle is relatively moved in a direction intersecting the one direction with respect to the surface of the light shielding film. More specifically, a resist film is formed on the substrate by scanning the substrate relative to a capillary nozzle that raises the resist solution by capillary action. The resist solution is sequentially drawn from the nozzle tip as the substrate moves.

  However, the light shielding film of the metal silicide material has poor wettability with respect to the resist solution. Therefore, when a resist film is formed on the metal silicide-based light-shielding film by the above method, it becomes difficult to draw out the resist solution from the slit, and uneven application of the resist film is likely to occur. Moreover, even if it can apply | coat to the whole board | substrate, in-plane film thickness uniformity tends to worsen. Therefore, forming a resist film by the above method on the light shielding film of the metal silicide material may cause a decrease in pattern accuracy during photomask manufacturing. Even if the resist film can be formed, the adhesion between the light-shielding film and the resist film is poor, so that the resist film may be peeled off during photomask manufacturing, resulting in pattern defects. Therefore, conventionally, there has been a problem that it is difficult to use a light shielding film of a metal silicide material in an FPD mask blank.

  Then, an object of this invention is to provide the mask blank and photomask which can solve said subject.

In order to solve the above problems, the present invention has the following configuration.
(Configuration 1) A mask blank for manufacturing an FPD device, a substrate, a light shielding film formed on the substrate using a metal silicide as a material, and an upper layer film formed on the light shielding film with a material containing chromium The light shielding film and the upper layer film are films to be wet etched using an etching mask obtained by patterning a resist film formed on the upper layer film, and the resist film is a resist extending in one direction on the upper layer film. The resist liquid is discharged from a nozzle having a liquid supply port, and the nozzle is relatively moved in a direction crossing the one direction with respect to the upper film surface. The upper layer film is, for example, a single chromium film or a film obtained by adding at least one element of oxygen, nitrogen, and carbon to chromium.

  When configured in this way, the use of a light shielding film made of a metal silicide material improves the chemical resistance during photomask manufacturing. As a result, it becomes easy to manufacture a mask having optical characteristics as designed, the fluctuation range of the optical characteristics is small, and the pattern transfer characteristics are good.

  Furthermore, the light shielding film made of a metal silicide-based material has higher adhesion to a substrate such as synthetic quartz than a light-shielding film made of a chromium-based material. In addition, the occurrence of defects due to film peeling from the shield can be reduced. Therefore, if comprised in this way, the mask blank suitable for manufacturing an FPD device can be provided.

  Further, the upper film of the above composition has better wettability with respect to the resist solution than the light shielding film of the above composition. Therefore, the adhesiveness with the resist film is improved, and the slit coater can be used appropriately. Thereby, high application | coating precision and a high yield are realizable. In addition, it is possible to realize coating unevenness accuracy and in-plane film thickness uniformity required for an FPD mask blank. Therefore, by using a photomask manufactured from the mask blank having this configuration, the display unevenness of the manufactured FPD device can also be reduced. Further, there is almost no possibility that the resist film is peeled off during the production of the photomask to cause pattern defects.

  Here, if the in-plane film thickness uniformity of the resist film is insufficient, the pattern line width uniformity (CD accuracy) decreases during photomask manufacturing, which causes display unevenness of the FPD device. Therefore, the in-plane film thickness uniformity required for the resist film is determined according to the size of CD accuracy allowed for the photomask.

  The in-plane film thickness uniformity of the resist film is required to be, for example, 1000 angstroms or less, more preferably 500 angstroms or less.

  (Configuration 2) The upper layer film is a film obtained by adding at least one of oxygen and nitrogen to chromium, and functions as an antireflection film in a photomask manufactured using a mask blank. If comprised in this way, a process man-hour can be reduced compared with the case where an upper film is formed, for example with a mere metal, and an antireflection film is provided separately. Further, such an upper layer film has good adhesion to the light shielding film of the metal silicide material, and also has good wettability with respect to the resist solution. Therefore, it is particularly suitable as an upper layer film to be formed on the light shielding film having the above composition. Therefore, with this configuration, the in-plane film thickness uniformity of the resist film can be further appropriately increased. This also makes it possible to improve the CD accuracy of the photomask pattern.

  Note that a film having the same composition as the upper film is generally formed as an antireflection film on a light shielding film of a chromium-based material, for example. However, in the case of the configuration 2, not only the function as an antireflection film is exhibited, but also the wettability with respect to the resist solution, which is a problem in the light shielding film of the metal silicide material, can be improved. Therefore, if comprised in this way, the outstanding characteristic of a metal silicide type | system | group material can be exhibited more appropriately.

  (Configuration 3) The film thickness of the upper layer film is 50 to 400 angstroms. If comprised in this way, the wettability with respect to a resist liquid required when using a slit coater can be exhibited, without thickening an upper layer film more than necessary.

  The mask blank for FPD is larger than the mask blank for LSI and the like, and the influence of the film stress of the thin film formed on the substrate is increased. Therefore, in the mask blank for FPD, it is particularly important to reduce the thickness of the thin film. Further, from the viewpoint of appropriately controlling the cross-sectional shape formed by wet etching, reduction of the film thickness is strongly demanded.

  Moreover, if comprised in this way, the optical characteristic of the light shielding film of a metal silicide type | system | group material can be exhibited appropriately about an optical density, for example. In this case, it is only necessary to design the optical characteristics of the photomask in consideration of only the light-shielding film of the metal silicide material having high chemical resistance, so that it becomes easy to manufacture a mask having the optical characteristics as designed.

  In addition, when the film thickness of an upper layer film is too thin, there exists a possibility that the wettability with respect to a resist liquid may be insufficient. If the upper layer film is too thick, it becomes difficult to control the cross-sectional shape in wet etching of the light shielding film. For this reason, the etching accuracy of the light shielding film may be lowered. Furthermore, if the upper layer film is too thick, the influence of the upper layer film becomes too great, and the optical characteristics of the light shielding film of the metal silicide material cannot be exhibited appropriately.

  (Configuration 4) The metal is a material containing any of molybdenum (Mo), tantalum (Ta), titanium (Ti), and tungsten (W). With such a configuration, the chemical resistance at the time of manufacturing the photomask and the adhesion to the substrate are good, and in addition to the low defect, the pattern controllability to the wet etching solution is improved.

  (Configuration 5) A photomask for manufacturing an FPD device manufactured using the mask blank according to any one of Configurations 1 to 4. If comprised in this way, the effect similar to the structures 1-4 can be acquired. The photomask is manufactured by patterning a light shielding film or the like formed on a mask blank by wet etching to form a mask pattern, for example.

  In each of the above-described configurations, the mask blank and mask for FPD include mask blanks and masks for manufacturing FPD devices such as LCD (liquid crystal display), plasma display, and organic EL (electroluminescence) display. .

  LCD masks include all masks necessary for LCD production, such as TFT (thin film transistor), especially TFT channel and contact hole, low-temperature polysilicon TFT, color filter, reflector (black matrix), etc. A mask for forming the is included. Other masks for manufacturing display devices include all masks necessary for manufacturing organic EL (electroluminescence) displays, plasma displays, and the like.

  A mask blank and a photomask suitable for a photomask for FPD can be provided. In addition, it is possible to provide a mask blank and a photomask in which a decrease in pattern line width uniformity (CD accuracy) in a photomask that causes display unevenness of an FPD device is suppressed.

Hereinafter, embodiments according to the present invention will be described with reference to the drawings.
FIG. 1 shows an example of the configuration of a mask blank 10 according to an embodiment of the present invention. The mask blank 10 is a mask blank for manufacturing an FPD device. Moreover, this mask blank is a large-sized mask blank whose side is 330 mm or more (for example, 330 mm × 450 mm to 1220 mm × 1400 mm), for example. In addition, an FPD photomask manufactured from the mask blank is used by being mounted on, for example, a mirror projection (scanning exposure method, equal magnification projection exposure) method or a lens projection type exposure device using a lens. . This photomask is, for example, a photomask for multi-color wave exposure using light in a wavelength band extending from i-line to g-line, and has, for example, a gray tone pattern of 1 μm or less.

  The mask blank 10 includes a substrate 12, a light shielding film 14, an upper layer film 16, and a resist film 18. The mask blank 10 may further include other layers such as a base film and a semi-transparent film. The substrate 12 is a translucent substrate, for example. Examples of the translucent substrate include synthetic quartz, soda lime glass, non-alkali glass and the like.

  The light shielding film 14 and the upper layer film 16 are generally wet-etched using an etching mask obtained by patterning the resist film 18 in the photomask manufacturing process. The light shielding film 14 is a light shielding film made of a metal silicide containing metal and silicon. For example, molybdenum silicide (MoSi), tantalum silicide (TaSi), titanium silicide (TiSi), or tungsten silicide (WSi) is used as a material. It is a light shielding film and is formed on the substrate 12.

  The upper layer film 16 is a layer formed on the light shielding film 14 in order to improve the wettability with respect to the resist solution. The upper layer film 16 is formed of a material containing chromium, for example, chromium oxide (CrO), chromium oxynitride (CrON), or the like. The film thickness of the upper layer film 16 is, for example, 50 to 400 angstroms, more preferably 50 to 300 angstroms, and still more preferably 100 to 250 angstroms. Further, in this example, the upper layer film 16 is made of a chromium film material (chromium oxide (CrO) or chromium oxynitride (CrON)) containing oxygen, so that it is reflected on a photomask manufactured using the mask blank 10. It can function as a prevention film.

  When the upper layer film 16 is an oxidized chromium film (CrO), it is formed by a reactive sputtering method using a sputtering target made of chromium and in a mixed gas atmosphere containing an oxygen gas in an inert gas such as an argon gas. Or a sputtering target containing chromium and oxygen and formed by sputtering in an atmosphere containing an inert gas such as argon gas, or after forming a chromium film by a known method, An oxidized chromium film (CrO) can be formed by heat treatment in an atmosphere.

  When the upper film 16 is an oxynitrided chromium film (CrON), a sputtering target made of chromium is used, and an inert gas such as argon gas, oxygen gas and nitrogen gas, nitrogen monoxide gas, and nitrogen dioxide are used. Formed by reactive sputtering in a mixed gas atmosphere containing a gas such as gas, or by sputtering in an atmosphere containing an inert gas such as argon gas using a sputtering target containing chromium, oxygen and nitrogen Alternatively, after a chromium film is formed by a known method, an oxygen nitrided chromium film (CrON) can be formed by heat treatment in the air or an atmosphere containing oxygen and nitrogen.

  The resist film 18 is formed on the upper layer film 16 using a slit coater. In this example, the resist film 18 is a resist film for laser drawing. Further, the resist film is not limited to a laser drawing resist film, and may be an electron beam drawing resist film. Further, either a positive resist film or a negative resist film may be used. In the case of a resist film for laser drawing, the thickness of the resist film 18 is preferably set to a film thickness for preventing deterioration of the pattern cross-sectional shape due to standing waves due to the drawing wavelength of the laser drawing apparatus.

  If comprised as mentioned above, the wettability with respect to a resist liquid required when using a slit coater can be exhibited appropriately by forming the upper layer film 16. This also makes it possible to appropriately use the light shielding film 14 made of a metal silicide material in the FPD mask blank. Therefore, a mask blank suitable for manufacturing an FPD device can be provided.

  When a transfer pattern is formed by the light shielding film 14 and the upper layer film 16 so as to be transferred to the transfer object, the total film thickness of the light shielding film 14 and the upper layer film 16 is an exposure used when manufacturing an FPD device. The film thickness is set so that the optical density (OD) is 3 or more with respect to the wavelength of the apparatus. Further, when a transfer pattern is formed so as to be transferred onto the transfer object only by the light shielding film 14, the film thickness of the light shielding film 14 is set to an optical density (OD) with respect to the wavelength of the exposure apparatus used when manufacturing the FPD device. ) To set the film thickness to 3 or more. When it is used as multicolor wave exposure using light in a wavelength band extending from i-line to g-line, the optical density (OD) is preferably 850 angstroms or more in order to obtain 3 or more. In consideration of forming a fine pattern, it is preferable that the film thickness is small, and the film thickness is preferably 1800 angstroms or less. Considering both, 850 to 1800 angstroms, more preferably 950 to 1500 angstroms is desirable.

  In this example, the upper layer film 16 can be used as an antireflection film. In this case, after the light shielding film 14 and the upper layer film 16 are patterned in the photomask manufacturing process, the upper layer film 16 is not removed. Left behind. When the upper layer film 16 is not used as an antireflection film, in the photomask manufacturing process, the light shielding film 14 and the upper layer film 16 are patterned, and then the upper layer film 16 is removed.

Hereinafter, the present invention will be described in more detail based on examples.
Example 1
A light shielding film and an upper layer film were formed on a large glass substrate (synthetic quartz (QZ) 10 mm thick, size 850 mm × 1200 mm) using a large in-line sputtering apparatus. For film formation, MoSi ₂ targets (Mo: 33 mol%, Si: 67 mol%) and Cr targets are respectively arranged in each space (sputter chamber) continuously arranged in a large in-line sputtering apparatus. In the first sputtering chamber, a light shielding film of MoSi ₂ film was formed to 750 Å using Ar gas as a sputtering gas with respect to the MoSi ₂ target. Next, in the next sputtering chamber, Ar gas and NO gas were used as sputtering gas for the Cr target, and an upper layer film of the CrON film was formed to 250 angstroms to produce a large mask blank for FPD.

  Using the mask blank prepared above, after a cleaning process (pure water, room temperature), a resist solution is applied using a known slit coater (slit coater described in JP-A-2005-286232), and developed. Using the resist pattern as a mask, the upper layer film is patterned by wet etching using a Cr etching solution, and then the light shielding film is patterned by wet etching using an MoSi etching solution. A large photomask for FPD was prepared. This photomask has a normal pattern with a width of 5 μm and a gray tone pattern with a width of 1 μm. This gray tone pattern is a pattern composed of a fine light-shielding pattern and a fine transmissive part that are below the resolution limit of a large FPD exposure machine. The resist solution was applied by setting the distance between the nozzle and the substrate surface, the width of the nozzle, the scanning speed of the nozzle, etc. so that the resist average film thickness was 1 μm. The resist film coated on the mask blank had no coating unevenness, and the in-plane film thickness uniformity was 450 angstroms. The in-plane film thickness uniformity refers to the difference between the maximum value and the minimum value of the resist film thickness within the pattern formation region.

  The line width uniformity (CD accuracy) of the pattern by the light shielding film and the upper layer film in the obtained photomask was good, and the liquid crystal display device manufactured using this photomask was also good with no display unevenness.

(Example 2)
A mask blank according to Example 2 in the same manner as in Example 1, except that Ar gas and O ₂ gas were used as the sputtering gas for forming the upper layer film, and the upper layer film was changed to a CrO film (thickness 150 Å). And the photomask was produced.

  In Example 2, the film thickness uniformity of the resist film was good as in Example 1. Further, the liquid crystal display device manufactured using the obtained photomask was also excellent with no display unevenness.

(Comparative Example 1)
A mask blank and a photomask according to Comparative Example 1 were produced in the same manner as in Example 1 except that the upper layer film was not formed. In Comparative Example 1, since the wettability with respect to the resist solution was poor, coating unevenness occurred in the resist film, and the resist film could not be formed on the entire substrate. For this reason, a photomask could not be produced appropriately.

(Example 3)
On a large glass substrate (synthetic quartz (QZ) 10 mm thick, size 850 mm × 1200 mm), a large in-line sputtering apparatus was used, and a MoSi ₂ film was deposited on a MoSi ₂ target using an Ar gas as a sputtering gas at 850 Å. Next, in the next sputtering chamber, an Ar gas was used as a sputtering gas for the Cr target, and an upper layer film of a Cr film was formed to a thickness of 50 angstroms to produce a large photomask blank for FPD.
Using the mask blank produced above, after a cleaning process (pure water, room temperature), a resist solution is applied using a known slit coater (slit coater apparatus described in JP-A-2005-286232), and resist is developed by development. Using this resist pattern as a mask, the upper layer film was patterned by wet etching with a Cr etchant, and then the light shielding film was patterned by wet etching with an MoSi etchant. Finally, the resist film was stripped with a resist stripping solution, and then the upper layer film formed on the light shielding film was stripped again with an etching solution for Cr to produce a large photomask for FPD. This photomask has a normal pattern with a width of 5 μm and a gray tone pattern with a width of 1 μm. This gray tone pattern is a pattern composed of a fine light-shielding pattern and a fine transmissive part that are below the resolution limit of a large FPD exposure machine. The resist solution was applied by setting the distance between the nozzle and the substrate surface, the width of the nozzle, the scanning speed of the nozzle, etc. so that the resist average film thickness was 1 μm. The resist film coated on the mask blank had no coating unevenness, and the in-plane film thickness uniformity was 500 angstroms.
The obtained photomask had good line width uniformity (CD accuracy) due to the light-shielding film and the upper layer film, and the liquid crystal display device manufactured using this photomask was also good with no display unevenness.

  As mentioned above, although this invention was demonstrated using embodiment, the technical scope of this invention is not limited to the range as described in the said embodiment. It will be apparent to those skilled in the art that various modifications or improvements can be added to the above embodiment. It is apparent from the description of the scope of claims that embodiments with such changes or improvements can be included in the technical scope of the present invention.

  The present invention can be suitably applied to, for example, a mask blank and a mask for manufacturing an FPD device.

It is a figure showing an example of composition of mask blank 10 concerning one embodiment of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Mask blank, 12 ... Substrate, 14 ... Light-shielding film, 16 ... Upper layer film, 18 ... Resist film

Claims (5)

A mask blank for manufacturing an FPD device,
The mask blank is a photomask having a gray-tone pattern that is a pattern composed of a fine light-shielding pattern and a fine transmission portion that are below the resolution limit of an exposure machine, and a normal pattern that is a pattern larger than the resolution limit of the exposure machine Is for manufacturing
A substrate,
A light-shielding film formed on and in contact with the substrate using metal silicide as a material;
An upper film formed on the light shielding film in contact with the light shielding film with a material containing chromium;
A resist film formed on the upper layer film;
With
The light shielding film and the upper layer film are films to be wet-etched using an etching mask obtained by patterning the resist film,
The upper layer film is a film that is wet etched using an etching solution for Cr,
The light shielding film is a film that is wet etched using an etching solution for metal silicide after wet etching on the upper layer film,
The thickness of the light shielding film is 850 to 1800 angstroms,
The upper film is a film obtained by adding at least oxygen and nitrogen to chromium, and functions as an antireflection film in the photomask.
The film thickness of the upper layer film is 50 to 400 angstroms,
The resist film is moved relative to the surface of the upper layer film in a direction intersecting the one direction while discharging the resist solution from a nozzle having a resist solution supply port extending in one direction on the upper layer film. Formed,
The mask blank according to claim 1, wherein the resist film has an in-plane film thickness uniformity of 500 angstroms or less indicated by a difference between a maximum value and a minimum value of a resist film thickness in a pattern formation region.   The mask blank according to claim 1, wherein the metal is a material containing any one of molybdenum (Mo), tantalum (Ta), titanium (Ti), and tungsten (W).   A photomask for manufacturing an FPD device manufactured using the mask blank according to claim 1. A method of manufacturing a mask blank for manufacturing an FPD device,
The mask blank is a photomask having a gray-tone pattern that is a pattern composed of a fine light-shielding pattern and a fine transmission portion that are below the resolution limit of an exposure machine, and a normal pattern that is a pattern that is larger than the resolution limit of the exposure machine. Is for manufacturing
A light shielding film is formed on the substrate in contact with the substrate with a material made of metal silicide,
Forming an upper film made of a material containing chromium on the light shielding film in contact with the light shielding film,
While discharging a resist solution from a nozzle having a resist solution supply port extending in one direction, the resist film is formed on the upper layer film by moving the nozzle in a direction intersecting the one direction with respect to the surface of the upper layer film. Form the
The light shielding film and the upper layer film are films to be wet-etched using an etching mask obtained by patterning the resist film,
The upper layer film is a film that is wet etched using an etching solution for Cr,
The light shielding film is a film that is wet etched using an etching solution for metal silicide after wet etching on the upper layer film,
The thickness of the light shielding film is 850 to 1800 angstroms,
The upper film is a film obtained by adding at least oxygen and nitrogen to chromium, and functions as an antireflection film in the photomask.
The film thickness of the upper layer film is 50 to 400 angstroms,
The resist film is formed so that the in-plane film thickness uniformity indicated by the difference between the maximum value and the minimum value of the resist film thickness in the pattern formation region is 500 angstroms or less. Production method. Using the mask blank manufactured by the mask blank manufacturing method according to claim 4,
Patterning the resist film;
The upper layer film is patterned by wet etching using an etching solution for Cr ,
A photomask manufacturing method for manufacturing an FPD device, wherein the light shielding film is patterned by wet etching using an etching solution for metal silicide .

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