JP2012003287A - Method for manufacturing photo mask, and photo mask - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a photo mask with higher accuracy compared with the case that a photomask blank having a conventional light shielding film is used in an etching process of a light shielding film, by reducing pattern size variance caused by density dependency of patterns to be formed.SOLUTION: A photo mask is manufactured from a photomask blank having a light shielding film laminated with or without another film on a transparent substrate and composed of a metal or a metallic compound capable of being etched by fluorine-based dry etching; an anti-reflection film formed on the light shielding film and composed of a metal or a metallic compound capable of being etched by fluorine-based dry etching; and an etching mask film with a film thickness of 2 to 30 nm formed on the anti-reflection film and composed of a metal or a metallic compound which has resistance to the fluorine-based dry etching. A manufacturing method of the photomask includes resist patterning, chlorine-based dry etching, and fluorine-based dry etching.

Description

  The present invention relates to a method of manufacturing a photomask used for microfabrication of a semiconductor integrated circuit, a CCD (charge coupled device), a color filter for an LCD (liquid crystal display device), a magnetic head, and the like, and a photomask.

  In recent years, in semiconductor processing, circuit pattern miniaturization has become more and more necessary, especially due to high integration of large-scale integrated circuits. There is an increasing demand for miniaturization technology of contact hole patterns for wiring. For this reason, even in the manufacture of photomasks with circuit patterns written thereon, which are used in photolithography to form these wiring patterns and contact hole patterns, a technique capable of writing circuit patterns more finely and accurately along with the above-mentioned miniaturization. Is required.

  In order to form a photomask pattern with higher accuracy on the photomask substrate, it is first necessary to form a high-precision resist pattern on the photomask blank. Since optical lithography when processing an actual semiconductor substrate performs reduction projection, the photomask pattern is about four times as large as the actually required pattern size. The photomask that is the original plate is required to have higher accuracy than that required for pattern accuracy after exposure.

  Furthermore, in the lithography that is currently being performed, the circuit pattern to be drawn is a size that is considerably smaller than the wavelength of the light to be used. If a photomask pattern in which the circuit shape is four times as it is is used, The shape according to the photomask pattern is not transferred to the resist film due to the influence of light interference or the like that occurs during photolithography. Therefore, in order to reduce these influences, it may be necessary to process the photomask pattern into a more complicated shape than an actual circuit pattern (a shape to which so-called OPC: Optical Proximity Correction (optical proximity effect correction) or the like is applied). Therefore, even in lithography technology for obtaining a photomask pattern, a highly accurate processing method is currently required. Lithography performance may be expressed with a limit resolution, but this resolution limit is equivalent to or higher than the resolution limit required for optical lithography used in semiconductor processing processes using photomasks. Limiting resolution accuracy is required for the lithography technique in the photomask processing process.

  In the formation of a photomask pattern, a photoresist film is usually formed on a photomask blank having a light shielding film on a transparent substrate, a pattern is drawn with an electron beam, a resist pattern is obtained through development, and Using the resist pattern as an etching mask, the light-shielding film is etched to be processed into a light-shielding pattern. However, when miniaturizing the light-shielding pattern, keep the film thickness of the resist film as it was before miniaturization. If so, the ratio of film thickness to the pattern, the so-called aspect ratio, becomes large, the pattern shape of the resist deteriorates, and pattern transfer does not work well, and in some cases the resist pattern collapses or peels off. . Therefore, it is necessary to reduce the resist film thickness with miniaturization.

  On the other hand, many light-shielding film materials that have been etched using a resist as an etching mask have been proposed so far. Compound films have been used. As such a thing, as what comprised the light shielding film required for the photomask blank for ArF excimer laser exposure with a chromium compound, for example, Unexamined-Japanese-Patent No. 2003-195479 (patent document 1), Unexamined-Japanese-Patent No. 2003-195383 No. (Patent Document 2) and Japanese Patent No. 3093632 (Patent Document 3) report a chromium compound film having a thickness of 50 to 77 nm.

  However, chlorine-containing dry etching containing oxygen, which is a general dry etching condition for chromium-based films such as chromium compound films, often has a property of etching to an organic film to some extent, and etching is performed with a thin resist film. When it is performed, it is difficult to accurately transfer the resist pattern, and it is quite difficult to obtain a resist having high resolution and etching resistance capable of high-precision etching at the same time. For this reason, in order to achieve high resolution and high accuracy, it is necessary to reexamine the light shielding film material in order to switch from a method that depends only on resist performance to a method that also improves the performance of the light shielding film.

  Further, many studies have already been made on light-shielding film materials other than chromium-based materials, but recently, there is an example in which tantalum is used as a light-shielding film for ArF excimer laser exposure (Patent Document 4). : JP-A-2001-312043).

On the other hand, in order to reduce the burden on the resist at the time of dry etching, a method of using a hard mask has been tried for a long time. For example, in Japanese Patent Application Laid-Open No. 63-85553 (Patent Document 5), MoSi ₂ is used. It has been reported that an SiO ₂ film is formed on the substrate, and this is used as an etching mask when MoSi ₂ is dry etched using a gas containing chlorine, and the SiO ₂ film also functions as an antireflection film. It is described that it can.

  Further, metal silicide films, particularly molybdenum silicide films, have been studied for a long time. For example, Japanese Patent Laid-Open No. 63-85553 (Patent Document 5), Japanese Patent Laid-Open No. 1-142637 (Patent Document 6), As reported in JP-A-3-116147 (Patent Document 7), all of them basically use a film of silicon: molybdenum = 2: 1, and JP-A-4-246649 (Patent Document). Although a metal silicide film is also reported in the literature 8), the actual manufacturing process copes with miniaturization by improving a conventionally used chromium-based light shielding film.

  On the other hand, in a mask using a super-resolution technique such as a halftone phase shift mask or a Levenson type phase shift mask, the lower layer film or the substrate and the light shielding film are removed when removing the light shielding film at the portion where the light phase is changed during mask processing. In this sense, the chromium-based material conventionally used has been excellent, and thus the chromium-based material has been widely used.

JP 2003-195479 A JP 2003-195483 A Japanese Patent No. 3093632 JP 2001-312043 A JP-A 63-85553 Japanese Patent Laid-Open No. 1-142637 JP-A-3-116147 JP-A-4-246649 JP-A-7-140635

  The inventors of the present invention have studied materials and methods for forming a finer mask pattern with high accuracy. In many cases, a chromium-based material that has been conventionally used is used, and a resist pattern is formed on a chromium film. Dry transfer conditions containing chlorine and oxygen have been used in the transfer. In this method, a photoresist is first applied on a photomask blank having a light shielding film of a chromium-based material, a resist pattern is formed by, for example, electron beam exposure and subsequent development of the resist film, and the resist film is used as an etching mask. The resist pattern is transferred to the chromium film by etching the chromium-based material film.

  However, when the pattern width is reduced by this method, for example, when a linear resist pattern of 0.4 μm or less is transferred as a pattern model to the chromium light-shielding film, the dependence on density is very strong, and the resist formed on the photomask blank There are cases where a pattern with a large error can be obtained. In other words, the transfer characteristics with respect to the resist pattern are greatly different between an isolated pattern with few film patterns left around and an isolated space with many film patterns left in the surroundings, which makes it extremely difficult to make a highly accurate mask. It becomes difficult.

  This problem is a phenomenon that does not become a big problem when a resist pattern of 0.4 μm or more is used. If a resist pattern of about 0.3 μm is exposed when manufacturing a photomask, Although not a big problem, it becomes a big problem when manufacturing a photomask for forming a resist pattern of 0.1 μm or less.

  On the other hand, when considering solving the above problem by a method that does not use a chromium material for the light shielding film, the hard mask function by the chromium light shielding film used when etching a transparent substrate or a silicon-containing phase shift material is used. There is also a problem of how to grant.

  The present invention has been made to solve the above-described problems, and is required for photolithography using a finer photomask pattern, in particular, light having an exposure wavelength of 250 nm or less, such as an ArF excimer laser. In order to form a finer photomask pattern, the photomask blank that can achieve both high resolution and high-precision etching processing in the photomask used for this, that is, the pattern density dependency during etching processing It is an object of the present invention to provide a photomask manufacturing method and a photomask using a photomask blank capable of obtaining low sufficient processing accuracy.

  As a result of intensive studies to solve the above problems, the present inventor has found that a film that can be processed by fluorine-based dry etching is more fluorine-based dry than a chromium-based film that performs chlorine-based dry etching containing oxygen. It was found that the density dependency during etching was small. Therefore, as a result of examining a film that can be processed by fluorine-based dry etching, it was found that a film containing a transition metal and silicon is suitable. On the other hand, it was found that the dependency on the density can be reduced if the film of the chromium-based material is very thin, but it has been found that the film of the chromium-based material having such a film thickness cannot provide sufficient light shielding properties. .

Therefore, as a result of further investigation based on the above knowledge, the light shielding film is made of a metal or metal compound that can be etched by fluorine-based dry etching, in particular, a material containing a transition metal and silicon, and on the light shielding film. Photomask blank in which an etching mask film made of a metal or metal compound having resistance to fluorine-based dry etching is formed, preferably an antireflection film on a light shielding film, particularly an antireflection film containing a transition metal, silicon and nitrogen And an etching mask film, in particular, an etching mask film containing chromium and not containing silicon, or a photomask blank containing an etching mask film containing tantalum and not containing silicon on the antireflection film, or An etching mask film, particularly chromium, is contained on the light shielding film, and the chromium content is 50 atomic% or more. An etching mask film, and an antireflection film on the etching mask film, particularly a photomask blank containing an antireflection film containing chromium and oxygen and having a chromium content of less than 50 atomic%, The light-shielding film can be processed with high accuracy regardless of the density of the pattern, and even if the phase-shift film or substrate is etched after the light-shielding film pattern is formed, the phase-shift film or substrate is highly accurate. Thus, the inventors have found that a pattern can be transferred to the present invention and have made the present invention.

That is, the present invention provides the following photomask manufacturing method and photomask.
Claim 1:
In photolithography for forming a resist pattern of 0.1 μm or less using light having an exposure wavelength of 250 nm or less provided with a mask pattern having a region transparent to exposure light and an effective opaque region on a transparent substrate A method of manufacturing a photomask to be used,
A light-shielding film made of a metal or a metal compound, which can be etched by fluorine-based dry etching, laminated on a transparent substrate with or without another film;
An antireflection film made of a metal or a metal compound that can be etched by fluorine-based dry etching formed on the light shielding film;
An etching mask film made of a metal or a metal compound having resistance to fluorine-based dry etching formed on the antireflection film;
Using a photomask blank in which the thickness of the etching mask film is 2 to 30 nm,
After applying a resist to the photomask blank and patterning the resist, the etching mask film is patterned by performing chlorine-based dry etching,
Using the etching mask film as a mask, the antireflection film and the light shielding film are subjected to fluorine-based dry etching and patterned,
Strip the resist,
A method for manufacturing a photomask, comprising removing the etching mask film by chlorine-based dry etching.
Claim 2:
The light shielding film contains a transition metal and silicon, the ratio of transition metal to silicon (atomic ratio) is transition metal: silicon = 1: 4 to 1:15, and the transition metal content is 1 atom% or more and 20 The method for producing a photomask according to claim 1, wherein the amount is at most atomic%.
Claim 3:
2. The method for producing a photomask according to claim 1, wherein the light-shielding film is a transition metal silicon compound containing a transition metal, silicon, and nitrogen and having a nitrogen content of 5 atomic% to 40 atomic%.
Claim 4:
The transition metal silicon compound has a transition metal / silicon ratio (atomic ratio) of transition metal: silicon = 1: 1 to 1:10 and a transition metal content of 1 atomic% to 20 atomic%. The method of manufacturing a photomask according to claim 3.
Claim 5:
The transition metal silicon compound constituting the light shielding film is selected from transition metal silicon nitride, transition metal silicon oxynitride, transition metal silicon oxynitride carbide, and transition metal silicon oxynitride carbide. The manufacturing method of the photomask as described.
Claim 6:
6. The method of manufacturing a photomask according to claim 1, wherein the light shielding film has a thickness of 10 to 80 nm.
Claim 7:
7. The method of manufacturing a photomask according to claim 1, wherein the antireflection film contains the same metal as that contained in the light shielding film.
Claim 8:
8. The method for producing a photomask according to claim 7, wherein the antireflection film comprises a transition metal silicon compound containing a transition metal, silicon, and one or more selected from oxygen, nitrogen, and carbon.
Claim 9:
The composition of the transition metal silicon compound that constitutes the antireflection film is such that silicon is 10 atomic% to 50 atomic%, oxygen is 0 atomic% to 60 atomic%, nitrogen is 20 atomic% to 50 atomic%, and carbon is 9. The method for producing a photomask according to claim 8, wherein the atomic ratio is 0 atomic% to 20 atomic%, and the transition metal is 1 atomic% to 35 atomic%.
Claim 10:
The photomask manufacturing method according to any one of claims 1 to 9, wherein a fluorine-based dry etching selection ratio of the light shielding film to the etching mask film is 2 or more.
Claim 11:
11. The photomask according to claim 1, wherein the etching mask film is made of chromium alone, or a chromium compound containing chromium and at least one selected from oxygen, nitrogen, and carbon. Manufacturing method.
Claim 12:
12. The method of manufacturing a photomask according to claim 11, wherein the chromium compound has a chromium content of 50 atomic% or more.
Claim 13:
11. The method of manufacturing a photomask according to claim 1, wherein the etching mask film is made of tantalum alone or a tantalum compound containing tantalum and not containing silicon.
Claim 14:
11. The photo according to claim 1, wherein the etching mask film is a film containing chromium and not containing silicon, or a film containing tantalum and containing no silicon. Mask manufacturing method.
Claim 15:
The photomask according to claim 1, wherein the transition metal is at least one selected from titanium, vanadium, cobalt, nickel, zirconium, niobium, molybdenum, hafnium, tantalum, and tungsten. Manufacturing method.
Claim 16:
The method of manufacturing a photomask according to claim 1, wherein the transition metal is molybdenum.
Claim 17:
The photomask manufacturing method according to any one of claims 1 to 16, wherein the other film is stacked via a phase shift film.
Claim 18:
18. The method of manufacturing a photomask according to claim 17, wherein the phase shift film is a halftone phase shift film.
Claim 19:
The photomask obtained by the manufacturing method of any one of Claims 1 thru | or 18.

  By using the photomask blank of the present invention, the pattern size variation caused by the density dependency of the pattern to be formed in the dry etching process of the light shielding film, compared with the case of using the conventional photomask blank having the light shielding film Can be made smaller, and a mask with higher accuracy can be manufactured. Furthermore, when the photomask blank of the present invention is applied to a halftone phase shift mask, a CPL (Chromeless Phase Lithography) mask, and a Levenson-type mask, a highly accurate super-resolution photomask can be manufactured.

  According to the present invention, a light-shielding film can be formed by fluorine dry etching with a small amount of side etching and good controllability, and the resist film can be thinned, so that a fine photomask pattern can be formed with high accuracy. It becomes possible. Further, in the case of the configuration having the phase shift film, the phase shift film can be etched using the etching mask film, but the film thickness of the etching mask film is the minimum necessary for etching the phase shift film. The film thickness can be set. In addition, even with a Levenson-type mask or CPL mask that is patterned by etching a transparent substrate, the thickness of the etching mask film can be set to the minimum as described above, so a fine photomask pattern can be formed with high accuracy. It becomes possible to do.

It is a figure which shows an example (example of a 1st aspect) of the photomask blank of this invention, (A) is what laminated | stacked the light shielding film directly on the transparent substrate, (B) is a light shielding film transparent substrate It is sectional drawing which shows what was laminated | stacked through the phase shift film | membrane on the top. It is a figure which shows an example (example of a 2nd aspect) of the photomask blank of this invention, (A) is what laminated | stacked the light shielding film directly on the transparent substrate, (B) is a light shielding film transparent substrate It is sectional drawing which shows what was laminated | stacked through the phase shift film | membrane on the top. It is a figure explaining the process of the manufacturing method of the photomask of this invention, and is sectional drawing which shows the process of manufacturing the binary mask which removed the etching mask film | membrane using the photomask blank of a 1st aspect. It is a figure explaining the process of the manufacturing method of the photomask of this invention, and is sectional drawing which shows the process of manufacturing the binary mask which left the etching mask film | membrane using the photomask blank of a 2nd aspect. It is a figure explaining the process of the manufacturing method of the photomask of this invention, and is sectional drawing which shows the process of manufacturing the halftone phase shift mask which removed the etching mask film | membrane using the photomask blank of a 1st aspect. It is a figure explaining the process of the manufacturing method of the photomask of this invention, and is sectional drawing which shows the process of manufacturing the halftone phase shift mask which left the etching mask film | membrane using the photomask blank of a 2nd aspect. It is a figure explaining the process of the manufacturing method of the photomask of this invention, and is sectional drawing which shows the process of manufacturing the Levenson type mask which removed the etching mask film | membrane using the photomask blank of a 1st aspect. It is a figure explaining the process of the manufacturing method of the photomask of this invention, and is sectional drawing which shows the process of manufacturing the Levenson type mask which left the etching mask film | membrane using the photomask blank of a 2nd aspect. It is a figure explaining the process of the manufacturing method of the photomask of this invention, and is sectional drawing which shows the process of manufacturing the chromeless mask which removed the etching mask film | membrane using the photomask blank of a 1st aspect. It is a figure explaining the process of the manufacturing method of the photomask of this invention, and is sectional drawing which shows the process of manufacturing the chromeless mask which left the etching mask film | membrane using the photomask blank of a 2nd aspect. It is the graph which plotted the dry etching rate by the chlorine gas in the chromium-type material film | membrane measured in Experimental example 2 with respect to the chromium content in a chromium-type material film | membrane.

Hereinafter, the present invention will be described in more detail.
The photomask blank of the present invention is a photomask blank serving as a photomask material provided with a mask pattern having a transparent region and an effectively opaque region with respect to exposure light on a transparent substrate. A light-shielding film made of a metal or a metal compound that can be etched by fluorine-based dry etching laminated with or without another film, and a metal or metal having resistance to fluorine-based dry etching formed on the light-shielding film And an etching mask film made of a compound.

  As preferred embodiments of the photomask blank of the present invention, there are the following two embodiments.

  The first aspect is a light-shielding film made of a metal or a metal compound that can be etched by fluorine-based dry etching, laminated on a transparent substrate with or without another film, and an antireflection film formed on the light-shielding film. A film and an etching mask film made of a metal or a metal compound having resistance to fluorine-based dry etching formed on the antireflection film.

  Specifically, the light shielding film is laminated on the transparent substrate without any other film. For example, the light shielding film 2 is directly laminated on the transparent substrate 1 as shown in FIG. The antireflection film 3 and the etching mask film 4 are sequentially stacked on the light shielding film 2 in contact with each other. Moreover, as what laminated | stacked the light shielding film through the other film | membrane on the transparent substrate, what was laminated | stacked through the phase shift film as this other film | membrane is mentioned, for example, it shows in FIG.1 (B). The light shielding film 2 is laminated | stacked on the transparent substrate 1 through the phase shift film 8, and the antireflection film 3 and the etching mask film | membrane 4 were laminated | stacked on this light shielding film 2 in contact with each other in order. In the case of the first aspect, it is preferable that the antireflection film contains the same metal as that contained in the light shielding film.

  Further, the second aspect is formed on the light-shielding film and a light-shielding film made of a metal or a metal compound that can be etched by fluorine-based dry etching, which is laminated on the transparent substrate with or without another film. It has an etching mask film made of a metal or a metal compound resistant to fluorine-based dry etching, and an antireflection film formed on the etching mask film.

  Specifically, the light shielding film is laminated on the transparent substrate without any other film. For example, the light shielding film 2 is directly laminated on the transparent substrate 1 as shown in FIG. In this case, an etching mask film 4 and an antireflection film 3 are sequentially stacked on the light shielding film 2 in contact with each other. Moreover, as what laminated | stacked the light shielding film through the other film | membrane on the transparent substrate, what was laminated | stacked through the phase shift film as this other film | membrane is mentioned, for example, it shows in FIG.2 (B). The light shielding film 2 is laminated on the transparent substrate 1 via the phase shift film 8, and the etching mask film 4 and the antireflection film 3 are sequentially laminated on the light shielding film 2. In the case of the second aspect, it is preferable that the antireflection film contains the same metal as that contained in the etching mask film.

  In any of the embodiments, the antireflection film and the etching mask film are composed of different constituent elements or the same constituent elements and different composition ratios.

  Here, the etching mask film is a film mainly responsible for the etching mask function in fluorine-based dry etching such as a light shielding film, the light shielding film is a film mainly responsible for the light shielding function for exposure light, and the antireflection film is When a photomask is used, it is a film mainly responsible for the antireflection function, that is, the function of reducing the reflectance with respect to exposure light and inspection light. Further, in the present invention, when simply referred to as “metal”, the metal in this case includes silicon.

  With such a configuration of the photomask blank, the surface reflectance can be controlled well, a fine pattern can be accurately formed during dry etching of the light shielding film, and the pattern generated by the density dependency of the pattern to be formed The size variation can be reduced, and a highly accurate photomask can be manufactured.

  That is, a metal or a metal compound capable of etching the light shielding film by fluorine-based dry etching, preferably silicon alone, an alloy containing silicon as a metal, or a metal compound containing silicon as a metal (hereinafter collectively referred to as silicon-containing materials) In other words, the density dependency in dry etching can be improved as compared with a commonly used chromium-based light shielding film. In addition, silicon has a large absorption coefficient for short-wavelength light compared to conventionally used chromium-based materials, so that a silicon-containing material can provide a sufficiently large light-shielding performance with a thin film. It is also possible to reduce the film thickness.

  Further, by forming an etching mask film resistant to the fluorine-based gas used for etching the light shielding film on this, the etching mask film functions as an etching mask in fluorine-based dry etching. In this case, since the resist only needs to function as an etching mask when patterning the etching mask film, the resist film can be thinned, and thus a fine resist pattern can be easily formed. Further, the etching mask film can prevent the pattern cross-sectional shape from being deteriorated due to the thinning of the resist film during dry etching.

  On the other hand, since the surface reflectance can be reduced by the antireflection film, reflection of exposure light on the photomask surface can be prevented.

Fluorine-based dry etching is dry etching using a gas containing fluorine. The gas containing fluorine may be a gas containing elemental fluorine, such as fluorine gas, carbon such as CF ₄ , C ₂ F ₆ , and the like. A gas containing fluorine, a gas containing sulfur and fluorine such as SF ₆ , or a mixed gas of a gas not containing fluorine such as helium and a gas containing fluorine may be used. Moreover, you may add gas, such as oxygen, as needed.

  Currently used super-resolution photomasks such as halftone phase shift masks, chromeless masks, Levenson-type masks, etc., try to increase the light contrast in lithography using the interference effect of light with different phases. The phase of light passing through the mask is controlled by the material and film thickness of the phase shift portion formed on the mask. In the production of a super-resolution photomask that normally uses the phase shift effect, a photomask blank having a light shielding film formed thereon is used. First, the light shielding film formed on the phase shift film or the transparent substrate is used. The pattern of the phase shift portion is formed by the method of performing the pattern processing and then transferring the pattern to the phase shift film or the transparent substrate. Therefore, first, it is very important that the pattern of the light shielding film is precisely processed.

  A normal phase shift film used for a phase shift mask is a material obtained by adding oxygen and / or nitrogen to a transition metal silicide in a halftone phase shift mask, and a transparent substrate itself or a laminated layer in a chromeless mask or a Levenson type mask. In any case, it is a material that uses fluorine-based dry etching when processing. Therefore, a chromium-based material has been conventionally used as the light shielding film material. This chromium-based material is resistant to fluorine-based dry etching conditions, can be used as a good etching mask in fluorine-based dry etching, and is a dry material containing chlorine that does not damage silicon-containing materials. It was a preferable light shielding film material that can be removed by etching conditions, for example, chlorine-based dry etching represented by dry etching using an etching gas containing chlorine and oxygen.

  However, in the present invention, since the light shielding film is a film that can be etched by fluorine-based dry etching, it does not function as a phase shift film etched by fluorine-based dry etching or an etching mask for a transparent substrate. Therefore, by separately forming a film resistant to dry etching with fluorine as an etching mask film, the etching mask film functions as a phase shift film or an etching mask for a transparent substrate.

  On the other hand, the problem of reduced processing accuracy due to pattern density dependency during processing of a conventional chromium-based light-shielding film material becomes a very serious problem when manufacturing a photomask for exposing a pattern of 0.1 μm or less. Therefore, in the photomask blank of the present invention, as with the phase shift film and the transparent substrate material, for example, a silicon-containing material that can be processed by fluorine-based dry etching is used for at least a part, preferably all of the light shielding film. To solve the problem.

  The specific film configuration of the photomask blank is roughly divided into a case where the etching mask film is finally removed in the photomask manufacturing process and a case where it remains without being removed.

  The photomask blank of the first aspect described above can be used as a photomask blank when the etching mask film is finally removed in the mask manufacturing process. With such a film structure, when the etching mask film is peeled off, an antireflection film is present on the outermost surface side of the photomask, and the reflectance of the photomask can be suppressed sufficiently low. In this case, it is preferable that the antireflection film can be etched under the same conditions as the etching of the light shielding film. Therefore, it is more preferable that the antireflection film contains the same metal as that contained in the light shielding film. More preferably, it is composed of a metal compound containing a large amount of oxygen and nitrogen.

  The antireflection film containing the same metal as the light shielding film can be etched together with the light shielding film. That is, the light shielding film and the antireflection film can be etched together by one dry etching using the etching mask film as a mask. In addition, it is preferable to use a silicon-containing material as the antireflection film because a low reflectance can be easily obtained even when the exposure wavelength is an ArF excimer laser.

  Further, in the case of the first aspect, as a photomask blank or in a photomask manufacturing process, an etching mask is used when a defect inspection is performed in a state where the etching mask film is present on the outermost surface portion of the photomask blank or the photomask. When it is necessary to adjust the reflectance of the film, a film having an antireflection function may be further formed on the etching mask film. In this case, the film having the antireflection function provided on the etching mask film can be finally removed together with the etching mask film.

  The photomask blank of the first aspect can also be used when the etching mask film is left as a part of the mask after manufacturing the mask. That is, this case corresponds to the case where the etching mask film has an auxiliary antireflection function of the antireflection film, or the case where the etching mask film functions as a protective film against chemicals used for cleaning or the like.

  The etching mask film may have a structure in which the function as the etching mask film and the function as the antireflection film are assigned to one film, but the etching mask film functions as an etching mask by separating the function from the antireflection film. It is also possible to achieve a minimum film thickness. In addition, when the etching mask function and the antireflection function are assigned to one film, adjusting the film quality and setting the light attenuation factor to a low value will deteriorate the function as an etching mask, but the etching mask film and the antireflection film Are independently provided, it is possible to achieve both low light attenuation and high etching resistance.

  The antireflection film has a different constituent element from the etching mask film or has the same constituent element and a different composition ratio. In the first aspect, the antireflection film is a metal that can be etched by fluorine-based dry etching. Or it is preferable to consist of a metal compound, for example, a silicon containing material is mentioned. Examples of the silicon-containing material include a silicon compound containing only silicon as a metal, and a silicon compound containing silicon alone, silicon, and one or more selected from oxygen, nitrogen, and carbon. More specific examples of the silicon compound include silicon oxide, silicon nitride, silicon oxynitride, silicon oxycarbide, silicon oxycarbide, and silicon oxynitride carbide.

  Further, as a metal containing silicon and a metal other than silicon, an alloy of transition metal and silicon, a transition metal, and a transition metal containing silicon and one or more selected from oxygen, nitrogen and carbon Silicon compounds are also suitable. More specifically, as the transition metal silicon compound, transition metal silicon oxide, transition metal silicon nitride, transition metal silicon oxynitride, transition metal silicon oxycarbide, transition metal silicon oxynitride, transition metal silicon oxynitride carbide, etc. Can be mentioned.

  As the transition metal, at least one selected from titanium, vanadium, cobalt, nickel, zirconium, niobium, molybdenum, hafnium, tantalum and tungsten is a suitable material, and in particular, molybdenum from the viewpoint of dry etching processability. It is preferable.

  The silicon-containing material of the antireflection film of the photomask blank of the first embodiment can be etched by fluorine-based dry etching, but can also be etched by chlorine gas not containing oxygen by selecting the composition.

  The composition of this antireflection film is 10 atomic% or more and 80 atomic% or less of silicon, particularly 30 atomic% or more and 50 atomic% or less, and oxygen is 0 atomic% or more and 60 atomic% or less, particularly 0 atomic% or more and 40 atomic% or less. Nitrogen is 0 atom% to 57 atom%, particularly 20 atom% to 50 atom%, carbon is 0 atom% to 20 atom%, particularly 0 atom% to 5 atom%, transition metal is 0 atom% to 35 atom%. It is preferably at most 1 atom%, particularly at least 1 atom% and at most 20 atom%.

  The antireflection film of the present invention may have a single layer structure or a multilayer structure. By adopting a single layer structure, the film configuration and the process reflecting this can be simplified.

  When the adhesion between the antireflection film and the light shielding film, the etching mask film, etc. is low, and pattern defects are likely to occur, or when a resist film is formed directly on the antireflection film during photomask manufacturing, When the resist pattern is squeezed or constricted and the cross-sectional shape is deteriorated, the part where the anti-reflection film is in contact with the light-shielding film, the etching mask film, etc. Is a material containing nitrogen and / or oxygen, for example, one or both of both end surfaces in the thickness direction of the antireflection film, or in the case of a multilayer structure, one or both of the layers located at both ends in the thickness direction of the antireflection film. The adhesion can be improved by adjusting the nitrogen and / or oxygen content. Further, it is possible to improve the perpendicularity of the cross-sectional shape of the etching pattern by forming the antireflection film so that the composition inclines continuously or stepwise in the thickness direction. These structures can be easily formed by controlling the sputtering conditions of reactive sputtering.

  In the case of the first aspect photomask blank, the composition of the antireflection film having a tilted composition in the thickness direction is 0 atomic% or more and 90 atomic% or less, particularly 10 atomic% or more and 90 atomic% or less, and oxygen is 0. Atom% to 67 atom%, especially 5 atom% to 67 atom%, nitrogen is 0 atom% to 57 atom%, particularly 5 atom% to 50 atom%, carbon is 0 atom% to 20 atom%, Particularly, it is preferable that the content is 0 atomic% to 5 atomic%, and the transition metal is 0 atomic% to 95 atomic%, particularly 1 atomic% to 20 atomic%.

  When the etching mask film is left without being finally removed in the photomask manufacturing process, the photomask blank of the second aspect described above can also be used. In this case, the antireflection film preferably has resistance to etching of the light shielding film.

  In this case, the antireflection film preferably contains the same metal as that contained in the etching mask film, and is provided on the antireflection film to improve adhesion to another film, for example, a resist. For example, the other film preferably contains the same metal as that contained in the etching mask film. With this configuration, the antireflection film can be removed by the same process as the etching mask film, and the other film can be removed by the same process as the etching mask film. The antireflection film can also have an auxiliary mask function of the etching mask film.

  The antireflection film has a different constituent element from the etching mask film or has the same constituent element and a different composition ratio. In the second aspect, the antireflection film is made of chromium alone, or chromium and oxygen, The chromium compound containing 1 or more types chosen from nitrogen and carbon is mentioned, The thing which does not contain silicon is preferable. More specific examples of the chromium compound include chromium oxide, chromium nitride, chromium oxynitride, chromium oxide carbide, chromium nitride carbide, and chromium oxynitride carbide.

  The composition of this antireflection film is such that chromium is 30 atomic% to 100 atomic%, especially 30 atomic% to 70 atomic%, especially 35 atomic% to 50 atomic%, oxygen is 0 atomic% to 60 atomic%, In particular, 20 atomic% to 60 atomic%, nitrogen is 0 atomic% to 50 atomic%, especially 3 atomic% to 30 atomic%, carbon is 0 atomic% to 20 atomic%, especially 0 atomic% to 5 atomic%. The following is preferable.

  In the case of the photomask blank of the second aspect, the composition of the antireflection film in which the composition in the thickness direction is inclined has a chromium content of 30 atomic% to 100 atomic%, particularly 35 atomic% to 90 atomic%, and oxygen of 0. Atom% to 60 atom%, especially 3 atom% to 60 atom%, nitrogen is 0 atom% to 50 atom%, particularly 3 atom% to 50 atom%, carbon is 0 atom% to 30 atom%, In particular, it is preferably 0 atom% or more and 20 atom% or less.

  In the present invention, the light shielding film is made of a metal or a metal compound that can be etched by fluorine-based dry etching, and examples thereof include a silicon-containing material. Examples of the silicon-containing material include silicon compounds containing silicon alone, silicon, and one or more selected from oxygen, nitrogen, and carbon. More specific examples of the silicon compound include silicon oxide, silicon nitride, silicon oxynitride, silicon oxycarbide, silicon oxycarbide, and silicon oxynitride carbide.

  A transition metal silicon compound containing an alloy of a transition metal and silicon, a transition metal, silicon, and one or more selected from oxygen, nitrogen, and carbon is also suitable. More specifically, as the transition metal silicon compound, transition metal silicon oxide, transition metal silicon nitride, transition metal silicon oxynitride, transition metal silicon oxycarbide, transition metal silicon oxynitride, transition metal silicon oxynitride carbide, etc. Can be mentioned.

  As the transition metal, at least one selected from titanium, vanadium, cobalt, nickel, zirconium, niobium, molybdenum, hafnium, tantalum and tungsten is a suitable material, and in particular, molybdenum from the viewpoint of dry etching processability. It is preferable.

  The silicon-containing material of this light-shielding film can be etched by fluorine-based dry etching, but can also be etched by chlorine gas not containing oxygen by selecting the composition.

  The composition of the light-shielding film is as follows: silicon is 10 atomic% to 95 atomic%, particularly 30 atomic% to 95 atomic%, oxygen is 0 atomic% to 50 atomic%, particularly 0 atomic% to 30 atomic%, and nitrogen is included. 0 atom% to 40 atom%, particularly 0 atom% to 20 atom%, carbon is 0 atom% to 20 atom%, particularly 0 atom% to 5 atom%, transition metal is 0 atom% to 35 atom% In particular, the content is particularly preferably 1 atomic percent or more and 20 atomic percent or less.

  The light shielding film of the present invention may have a single layer structure or a multilayer structure. By adopting a single layer structure, the film configuration and the process reflecting this can be simplified.

  When the adhesion between the light shielding film and the etching mask film, the antireflection film, the transparent substrate, the phase shift film, etc. is low and the pattern defect is likely to occur, the light shielding film is the etching mask film, the antireflection film, or the transparent substrate. In the case of a single layer structure, one or both of the both end surfaces in the thickness direction of the light shielding film, and in the case of a multilayer structure, the layers located at both ends in the thickness direction of the light shielding film. Adhesion can be improved by using one or both of the materials, for example, as a material containing nitrogen and / or oxygen and adjusting the content of nitrogen and / or oxygen. Further, it is possible to improve the perpendicularity of the cross-sectional shape of the etching pattern by forming the light shielding film so that the composition inclines continuously or stepwise in the thickness direction. These structures can be easily formed by controlling the sputtering conditions of reactive sputtering.

  The composition of the light-shielding film in which the composition in the thickness direction is inclined is 10 atomic% or more and 95 atomic% or less, particularly 15 atomic% or more and 95 atomic% or less, and oxygen is 0 atomic% or more and 60 atomic% or less, particularly 0 atom. % To 30 atomic%, nitrogen is 0 atomic% to 57 atomic%, especially 0 atomic% to 40 atomic%, carbon is 0 atomic% to 30 atomic%, especially 0 atomic% to 20 atomic%, transition It is preferable that the metal content is 0 atom% or more and 35 atom% or less, particularly 1 atom% or more and 20 atom% or less.

  Furthermore, when the silicon-containing material includes a transition metal and silicon, various composition ratios can be selected. For example, the composition ratio of the transition metal to silicon is set to transition metal: silicon = 1: 4 to 1. : 15 (atomic ratio) is preferable because stability is increased with respect to chemicals used for cleaning and the like. Moreover, even if the composition ratio of the transition metal and silicon is outside the above range, the necessary chemical stability can be obtained by including nitrogen, particularly by setting the nitrogen content to 5 atom% or more and 40 atom% or less. In particular, it is effective for reducing damage during dry etching of a chlorine-based gas containing oxygen when etching a Cr film used for an etching mask film or the like. At this time, the ratio of transition metal to silicon can be, for example, transition metal: silicon = 1: 1 to 1:10 (atomic ratio).

  The thickness of the light shielding film is preferably 10 to 80 nm. If the film thickness is less than 10 nm, a sufficient light-shielding effect may not be obtained. If it exceeds 80 nm, high-precision processing becomes difficult with a thin resist having a thickness of 250 nm or less, or the film stress causes warping of the substrate. There is a risk of

  In the present invention, the light-shielding film is a film that provides a light-shielding property against exposure light when using a photomask, and is not particularly limited. For example, a photomask blank in which a light-shielding film is directly laminated on a transparent substrate as shown in FIG. 1A or FIG. 2A, or FIG. In the case of a photomask blank in which a light shielding film is laminated on a transparent substrate as shown in FIG. 2B via a phase shift film, and the phase shift film is a complete transmission type phase shift film, It is preferable to adjust the film composition and film thickness so that the optical density in exposure light is 1 to 4. A suitable thickness of the light shielding film in this case is, for example, 20 to 80 nm.

  On the other hand, in addition to this light-shielding film, a film mainly having a light-shielding property of a photomask coexists, for example, a light-shielding film is formed on a transparent substrate as shown in FIGS. 1B and 2B. When the phase shift film is a halftone phase shift film having a transmittance of, for example, about 5 to 30%, the optical density of the light shielding film in the exposure light is a photomask blank laminated through the shift film. It is preferable to adjust the film composition and film thickness so as to be 0.2-4. In this case, a suitable thickness of the light shielding film is, for example, 10 to 70 nm.

  In the present invention, the film thickness of the antireflection film varies depending on the wavelength of exposure light in exposure using a photomask, the wavelength of light used for inspection required when producing or using a photomask, and the composition of the antireflection film, Usually, an antireflection effect is obtained by setting the film thickness to 8 to 30 nm, and it is preferably 8 to 25 nm particularly for ArF excimer laser exposure.

  In particular, in the case of a silicon-containing material suitable as an antireflection film in the photomask blank of the first aspect, the film thickness is preferably 10 to 30 nm. On the other hand, in the case of chromium alone or a chromium compound suitable as an antireflection film in the photomask blank of the second aspect, the film thickness is preferably 8 to 30 nm.

  The etching mask film having resistance to fluorine-based dry etching functions as an etching mask when etching the silicon-containing material constituting the light-shielding film, and contributes to increasing the accuracy when etching this film. . Also, it functions as an etching mask when a fluorine-based dry etching is performed on a transparent substrate or a phase shift film located below the light shielding film.

  The etching mask film in the present invention needs to be resistant to fluorine-based dry etching. For this reason, when the etching mask film has an etching selectivity with the light shielding film (fluorine dry etching selectivity of the light shielding film with respect to the etching mask film) of 2 or more in fluorine-based dry etching, the side etching amount of the pattern is suppressed. And a photomask blank capable of forming a finer pattern is preferable.

  Further, the etching selectivity in the fluorine-based dry etching between the etching mask film and the transparent substrate (fluorine-based dry etching selectivity of the transparent substrate with respect to the etching mask film) is set to 10 or more, so that the transparent substrate is etched and the photomask is etched. A photomask blank more suitable for manufacturing a Levenson-type or CPL-type photomask that forms the film.

  As such an etching mask film, a chromium-based material, a material containing tantalum and not containing silicon, or the like can be used.

  Examples of the chromium-based material include chromium alone or a chromium compound containing chromium and one or more selected from oxygen, nitrogen, and carbon, and those not containing silicon are preferable. More specific examples of the chromium compound include chromium oxide, chromium nitride, chromium oxynitride, chromium oxide carbide, chromium nitride carbide, and chromium oxynitride carbide. These materials have high resistance to fluorine-based dry etching.

  In particular, when the chromium content is 50 atomic% or more, particularly 60 atomic% or more, the fluorine-based dry etching resistance is good, and sufficient etching selectivity can be given to the light-shielding film and / or the transparent substrate. The mask film is preferable because a pattern can be formed by dry etching under dry etching conditions containing chlorine and oxygen.

  As the chromium-based material, for example, chromium is 50 atomic% to 100 atomic%, particularly 60 atomic% to 100 atomic%, oxygen is 0 atomic% to 50 atomic%, particularly 0 atomic% to 40 atomic%, Nitrogen is 0 atomic% or more and 50 atomic% or less, particularly 0 atomic% or more and 40 atomic% or less, and carbon is 0 atomic% or more and 20 atomic% or less, particularly 0 atomic% or more and 10 atomic% or less, thereby forming an etching mask film. In addition, a light-shielding film and / or a film that gives sufficient etching selectivity to the transparent substrate can be obtained.

  The etching mask film of the present invention can have a single layer structure or a multilayer structure. If a single-layer structure is used, the film configuration and the process reflecting this can be simplified.

  When the adhesion between the etching mask film and the light shielding film, the antireflection film, etc. is low and pattern defects are likely to occur, or when a resist film is formed directly on the etching mask film during photomask manufacturing, When the resist pattern is squeezed or constricted and the cross-sectional shape deteriorates, the etching mask film is in contact with the light shielding film, antireflection film, etc., or the resist film is in contact, that is, in the case of a single layer structure Is a material containing, for example, nitrogen and / or oxygen in one or both of both end surfaces in the thickness direction of the etching mask film, or in the case of a multilayer structure, one or both of the layers positioned at both ends in the thickness direction of the etching mask film The adhesion can be improved by adjusting the nitrogen and / or oxygen content. Further, it is possible to improve the perpendicularity of the cross-sectional shape of the etching pattern by forming the etching mask film so that the composition inclines continuously or stepwise in the thickness direction. These structures can be easily formed by controlling the sputtering conditions of reactive sputtering.

  The composition of the etching mask film in which the composition in the thickness direction is inclined is such that chromium is 50 atomic% to 100 atomic%, particularly 60 atomic% to 100 atomic%, and oxygen is 0 atomic% to 60 atomic%, particularly 0. Atomic% to 50 atomic%, nitrogen is 0 atomic% to 50 atomic%, particularly 0 atomic% to 40 atomic%, carbon is 0 atomic% to 20 atomic%, especially 0 atomic% to 10 atomic% Preferably there is.

  On the other hand, a material containing tantalum loses etching resistance against fluorine-based dry etching when silicon is included. However, when silicon is not included, for example, tantalum alone is etched to the extent that it can be selectively etched with a silicon-containing material. A tantalum compound that is resistant and contains tantalum and does not contain silicon, such as tantalum-zirconium, tantalum-hafnium, and the like, can give good etching selectivity to silicon-containing materials. . Note that these materials can be dry-etched by performing chlorine-based dry etching not containing oxygen, unlike the case of chromium-based materials.

  Note that the etching mask film having etching resistance to fluorine-based dry etching has a sufficiently thin film thickness so that the problem of dependency on the density of the transfer pattern during dry etching does not occur. Dependency issues are avoided. In the present invention, the density dependency of the transfer pattern is clearly lower than that of a conventional photomask blank using a film that cannot be etched by fluorine-based dry etching as a light shielding film.

  The thickness of the etching mask film can be appropriately selected according to the film configuration. Usually, in order to etch the silicon-containing material of the light shielding film, and to etch the phase shift film and the transparent substrate together with the light shielding film, a sufficient etching mask function can be obtained by setting the thickness to 2 to 55 nm. In particular, in order to achieve a lower density dependency, the thickness is preferably 2 to 30 nm.

  In the photomask blank of the present invention, a light-shielding film formed on a transparent substrate (which differs depending on the film configuration, but in addition to the light-shielding film, an auxiliary anti-reflection film that gives light-shielding properties (type of anti-reflection film) Depending on the type of the etching mask film, there may be an auxiliary light shielding property. In the case where an etching mask film is left when a photomask is used, an auxiliary etching mask film is provided. In order to function as a material having sufficient light shielding properties as a whole, the above light shielding properties when used as a photomask are provided. It is desirable that the optical density OD in the exposure light when the photomask of the entire film is used is 1 to 4.

  When the photomask is used after removing the etching mask film, the optical density OD is a combination of the light shielding film and the antireflection film. Further, when the halftone phase shift film is used together, the light shielding film and the reflection are used. It is preferable that the optical density OD of the prevention film and the halftone phase shift film is 2.5 or more, particularly 2.8 or more, particularly 3.0 or more.

  When the photomask is used without removing the etching mask film, an optical density OD that combines the etching mask film, the light shielding film, and the antireflection film, and a halftone phase shift film are used together. In this case, the optical density OD of the etching mask film, the light shielding film, the antireflection film, and the halftone phase shift film is preferably 2.5 or more, particularly 2.8 or more, particularly 3.0 or more.

Therefore, particularly when the light shielding film contains light elements such as oxygen, nitrogen, and carbon, if the light elements are contained in a certain amount or more, sufficient light shielding properties may not be obtained. For example, the photomask blank of the present invention exposure are particularly preferably by an applied wavelength 193nm or less of the light, for example, for an ArF excimer laser exposure wavelength 193nm, as the photomask blank of F such for ₂ laser exposure wavelength 153 nm, the content of nitrogen 40 atom% Hereinafter, it is preferable that the carbon content is 20 atomic% or less, the oxygen content is 10 atomic% or less, particularly the total of nitrogen, carbon, and oxygen is 40 atomic% or less, and at least a part, particularly all, of the light shielding film. With such a composition, good light shielding performance can be obtained.

The following two aspects are particularly preferable as the photomask blank of the present invention.
As a photomask blank of the first aspect, in particular, a light-shielding film containing transition metal and silicon that can be etched by fluorine-based dry etching laminated on a transparent substrate with or without another film, An antireflection film containing transition metal, silicon, and nitrogen laminated in contact with the light shielding film, and an etching mask film containing no chromium and containing chrome laminated on the antireflection film, or containing tantalum And a photomask blank having an etching mask film containing no silicon.

  In addition, as the photomask blank of the second aspect, in particular, a light-shielding film containing a transition metal and silicon that can be etched by fluorine-based dry etching, laminated on a transparent substrate with or without another film And an etching mask film containing chromium laminated in contact with the light-shielding film and having a chromium content of 50 atomic% or more, preferably 60 atomic% or more, and chromium and oxygen laminated in contact with the etching mask film. And an antireflection film having a chromium content of less than 50 atomic%, preferably 45 atomic% or less, is suitable.

  As the transparent substrate, a substrate mainly composed of silicon oxide such as a quartz substrate is suitable. On the other hand, when a phase shift film is used, a perfect transmission phase shift film or a halftone phase shift film, for example, a halftone phase shift film having a transmittance of 5 to 30% can be applied. Here, the phase shift film is preferably a film that can be etched by fluorine-based dry etching. The material of the phase shift film is a silicon-containing material, particularly a transition metal, a transition metal silicon compound containing silicon, and one or more selected from oxygen, nitrogen and carbon, especially a transition metal, silicon, and at least nitrogen. Those containing one of oxygen are preferable. Specific examples of the silicon-containing material include those exemplified as the silicon-containing compound of the light-shielding film, and examples of the transition metal include those exemplified as the transition metal of the light-shielding film. The film thickness of the phase shift film is set to a thickness that shifts the phase by a predetermined amount, usually 180 °, with respect to the exposure light when using the photomask.

  The silicon-containing material of this phase shift film can be etched by fluorine-based dry etching, but it can be made not to be etched by chlorine gas not containing oxygen by selecting the composition, and the photomask blank of the first aspect In the second photomask blank, the light shielding film and the light shielding film in the second photomask blank are made of a silicon-containing material that is etched with chlorine gas that does not contain oxygen. It is also possible to perform selective etching between the shift film and the light shielding film and the antireflection film (first aspect) or between the phase shift film and the light shielding film (second aspect).

  The etching mask film, the light-shielding film, the antireflection film, and the phase shift film can all be formed by known methods, but the method using sputtering is the easiest way to obtain a film with excellent uniformity. Preferably, any method such as DC sputtering or RF sputtering can be used.

  The target and sputtering gas are selected depending on the film composition. For example, the film formation using a chromium-based material can be performed by the same method as a conventional chromium-based film. As a commonly used method, a chromium target is used, and only an argon gas or a reactive gas such as nitrogen is used. Or a method of performing reactive sputtering in a mixed gas of a reactive gas such as nitrogen and an inert gas such as argon (see, for example, Patent Document 9: JP-A-7-140635). The flow rate of the sputtering gas may be adjusted according to the film characteristics, and may be constant during film formation. When the amount of oxygen or nitrogen is to be changed in the thickness direction of the film, it is changed according to the target composition. May be.

  When a film containing a transition metal and silicon is used, a target in which the content ratio of silicon and transition metal is adjusted may be used alone, or a silicon target, a transition metal target, and silicon and a transition metal. The ratio of silicon and transition metal is adjusted by appropriately selecting the target (transition metal silicide target) consisting of and adjusting the sputtering area of the target or sputtering using a plurality of targets and adjusting the power applied to the target. Also good. In addition, when light elements such as oxygen, nitrogen, and carbon are included, a film containing oxygen, a gas containing nitrogen, and a gas containing carbon are appropriately introduced as a reactive gas into the sputtering gas, and the film is formed by reactive sputtering. Is possible.

  When a film containing tantalum and not containing silicon is used, a target containing tantalum is used, and a target containing silicon is not used, and the film may be formed by the same method as the film containing the transition metal and silicon. .

  In the present invention, the photomask is formed by patterning each film of the above-described photomask blank into a desired pattern to form a mask pattern having a transparent area and an opaque area on the transparent substrate with respect to the exposure light. It is obtained by forming.

  In the photomask blank of the present invention, the light shielding film can be subjected to fluorine-based dry etching using the etching mask film as an etching mask, and the transparent substrate can be subjected to fluorine-based dry etching using the etching mask film as an etching mask.

A specific example of the photomask manufacturing process will be described in detail below with reference to the drawings.
(1) When removing the etching mask film in the photomask manufacturing process (binary mask)
A resist 5 is applied to the photomask blank (FIG. 3A) of the first embodiment formed on the transparent substrate 1 in the order of the light shielding film 2, the antireflection film 3, and the etching mask film 4, and then the resist After patterning 5 (FIG. 3B), chlorine-based dry etching is performed to pattern the etching mask film 4 (FIG. 3C). Next, using the resist 5 and the etching mask film 4 as a mask, the antireflection film 3 and the light shielding film 2 are subjected to fluorine dry etching and patterned (FIG. 3D). Thereafter, the resist 5 is peeled off (FIG. 3E), and the etching mask film 4 is removed by chlorine dry etching, whereby the antireflection film 3 appears on the surface of the photomask, and the photomask (FIG. 3F). ) Is completed.

(2) When the etching mask film is not removed in the photomask manufacturing process (binary mask)
A resist 5 is applied to the photomask blank (FIG. 4A) of the second embodiment formed on the transparent substrate 1 in the order of the light shielding film 2, the etching mask film 4, and the antireflection film 3, and then the resist 5 is patterned (FIG. 4B), chlorine-based dry etching is performed, and the antireflection film 3 and the etching mask film 4 are patterned (FIG. 4C). Next, using the resist 5, the antireflection film 3, and the etching mask film 4 as a mask, the light shielding film 2 is subjected to fluorine-based dry etching (FIG. 4D). Thereafter, the resist 5 is peeled off to complete a photomask (FIG. 4E).

(3) When removing the etching mask film in the photomask manufacturing process (halftone phase shift mask)
A halftone phase shift film 8 is formed on a transparent substrate 1, and a light mask film 2, an antireflection film 3, and an etching mask film 4 are formed in this order, and a photomask blank of the first aspect (FIG. 5A) ), After applying the first resist 6 and then patterning the first resist 6 (FIG. 5B), chlorine-based dry etching is performed to pattern the etching mask film 4 (FIG. 5B). C)). Next, using the first resist 6 and the etching mask film 4 as a mask, the antireflection film 3, the light shielding film 2, and the halftone phase shift film 8 are subjected to fluorine dry etching and patterned (FIG. 5D). ). Thereafter, the first resist 6 is peeled off (FIG. 5E), and the etching mask film 4 is removed by chlorine dry etching (FIG. 5F). Next, the second resist 7 is applied, the resist is left only in the portion where the light shielding film 2 is left (FIG. 5G), and the second resist 7 is used as a mask for dry etching with chlorine gas not containing oxygen. Then, the antireflection film 3 and the light shielding film 2 are removed (FIG. 5H). Thereafter, the second resist 7 is removed to complete the photomask (FIG. 5I).

(4) When the etching mask film is not removed in the photomask manufacturing process (halftone phase shift mask)
A halftone phase shift film 8 is formed on the transparent substrate 1, and a light mask film 2, an etching mask film 4, and an antireflection film 3 are formed in this order, and a photomask blank of the second mode (FIG. 6A). ), A first resist 6 is applied, and then the first resist 6 is patterned (FIG. 6B), chlorine-based dry etching is performed, and the antireflection film 3 and the etching mask film 4 are patterned. (FIG. 6C). Next, using the first resist 6, the antireflection film 3 and the etching mask film 4 as a mask, the light shielding film 2 and the halftone phase shift film 8 are subjected to fluorine-based dry etching (FIG. 6D). Thereafter, the first resist 6 is removed (FIG. 6E). Next, the second resist 7 is applied, leaving the resist only in the portion where the light-shielding film 2 is left (FIG. 6F), and using the second resist 7 as a mask, the anti-reflection film 3 is formed by chlorine dry etching. The etching mask film 4 is removed (FIG. 6G), and then the light shielding film 2 is removed by dry etching with chlorine gas not containing oxygen (FIG. 6H). Thereafter, the second resist 7 is removed to complete the photomask (FIG. 6I).

(5) When removing the etching mask film in the photomask manufacturing process (Levenson type mask)
A phase shift film is formed on the transparent substrate 1 as necessary (FIG. 7 shows a case where no phase shift film is provided), and a light shielding film 2, an antireflection film 3, and an etching mask film 4 are formed in this order. After applying the first resist 6 to the photomask blank of FIG. 1 (FIG. 7A) and then patterning the first resist 6 (FIG. 7B), chlorine-based dry etching is performed. Then, the etching mask film 4 is patterned (FIG. 7C). Next, using the first resist 6 and the etching mask film 4 as a mask, the anti-reflection film 3 and the light-shielding film 2 (in the case where a phase shift film is provided, together with the phase shift film), a fluorine-based dry Etching is performed for patterning (FIG. 7D). Thereafter, the first resist 6 is peeled off (FIG. 7E). Next, the 2nd resist 7 is apply | coated and the 2nd resist 7 is patterned into the pattern from which the part which etches the transparent substrate 1 was removed (FIG.7 (F)). Next, using the second resist 7 and the etching mask film 4 as a mask, the transparent substrate 1 is subjected to fluorine-based dry etching and patterned (FIG. 7G). Thereafter, the second resist 7 is removed (FIG. 7H), and then the etching mask film 4 is removed by chlorine-based dry etching, whereby the antireflection film 3 appears on the surface of the photomask, and the photomask ( FIG. 7 (I)) is completed.

(6) When the etching mask film is not removed after manufacturing the photomask (Levenson type mask)
A phase shift film is formed on the transparent substrate 1 as necessary (FIG. 8 shows a case where no phase shift film is provided), and a light shielding film 2, an etching mask 4, and an antireflection film 3 are formed in this order. The first resist 6 is applied to the photomask blank (FIG. 8A) of the embodiment, and then the first resist 6 is patterned (FIG. 8B), and then chlorine-based dry etching is performed. Then, the antireflection film 3 and the etching mask film 4 are patterned (FIG. 8C). Next, using the first resist 6, the antireflection film 3 and the etching mask film 4 as a mask, the fluorine-based dry etching is performed on the light shielding film 2 (in the case where a phase shift film is provided, together with the phase shift film). Then, patterning is performed (FIG. 8D). After that, the first resist 6 is peeled off (FIG. 8E). Next, the 2nd resist 7 is apply | coated and the 2nd resist 7 is patterned to the pattern from which the part which etches the transparent substrate 1 was removed (FIG.8 (F)). Next, using the second resist 7, the antireflection film 3 and the etching mask film 4 as a mask, the transparent substrate 1 is subjected to fluorine-based dry etching and patterned (FIG. 8G). After that, the second resist 7 is removed, and a photomask (FIG. 8H) is completed.

(7) When removing the etching mask film in the photomask manufacturing process (chromeless mask)
A first resist 6 is applied to the photomask blank (FIG. 9A) of the first embodiment formed on the transparent substrate 1 in the order of the light shielding film 2, the antireflection film 3, and the etching mask film 4. Thereafter, after patterning the first resist 6 (FIG. 9B), chlorine-based dry etching is performed to pattern the etching mask film 4 (FIG. 9C). Next, using the first resist 6 and the etching mask film 4 as a mask, the antireflection film 3 and the light shielding film 2 are subjected to fluorine-based dry etching and patterned (FIG. 9D), and the transparent substrate 1 is further formed. Etching is performed by fluorine-based dry etching (FIG. 9E). Thereafter, the first resist 6 is peeled off (FIG. 9F), and the etching mask film 4 is removed by chlorine-based dry etching (FIG. 9G). Next, the second resist 7 is applied, and only the portion where the light shielding film 2 is left is left (FIG. 9H), and the second resist 7 is used as a mask for dry etching with chlorine gas not containing oxygen. Then, the antireflection film 3 and the light shielding film 2 are removed (FIG. 9I). Thereafter, the second resist 7 is removed to complete the photomask (FIG. 9J).

(8) When the etching mask film is not removed after manufacturing the photomask (chromeless mask)
A phase shift film is formed on the transparent substrate 1 as necessary, and the photomask blank (FIG. 10 (A)) of the second mode in which the light shielding film 2, the etching mask 4, and the antireflection film 3 are formed in this order. Then, after applying the first resist 6 and then patterning the first resist 6 (FIG. 10B), chlorine-based dry etching is performed to pattern the antireflection film 3 and the etching mask film 4. (FIG. 10C). Next, using the first resist 6, the antireflection film 3 and the etching mask film 4 as a mask, the light shielding film 2 is subjected to fluorine-based dry etching and patterned (FIG. 10D), and the transparent substrate 1 is further treated with fluorine. Etching is performed by system dry etching (FIG. 10E). After that, the first resist 6 is peeled off (FIG. 10F). Next, the second resist 7 is applied, leaving the resist only in the portion where the light shielding film 2 is left (FIG. 10G), and using the second resist 7 as a mask, the antireflective film 3 is formed by chlorine dry etching. The etching mask film 4 is removed (FIG. 10H), and then the light-shielding film 2 is removed by dry etching with chlorine gas not containing oxygen (FIG. 10I). Thereafter, the second resist 7 is removed to complete the photomask (FIG. 10J).

  EXAMPLES Hereinafter, although an experiment example and an Example are shown and this invention is demonstrated concretely, this invention is not restrict | limited to the following Example.

[Experimental Example 1]
As a typical photomask blank model for an ArF exposure mask, a CrN light-shielding film (Cr: N = 9: 1 (atomic ratio)) with a thickness of 26 nm and a CrON antireflection film (Cr: O with a thickness of 20 nm) on a transparent substrate. : N = 4: 5: 1 (atomic ratio)) is prepared, and a pattern having a line width from 1.6 μm to 0.2 μm every 0.1 μm is coarsely and densely formed on this photomask blank. As a model, 1: 9 line and space (iso pattern model) and 9: 1 line and space (iso space model) are dry-etched with chlorine and oxygen (etching conditions: Cl ₂ = 20 sccm, O ₂ = 9 sccm). , He = 80 sccm, chamber internal pressure = 2 Pa).

  As a result, in the isospace, the size error between 1.6 μm and 0.2 μm is 5.3 nm in the width between the minimum value and the maximum value, whereas in the isopattern, from 1.6 μm to 0.5 nm. Although the width is 3.8 nm, it is 13.8 nm from 1.6 μm to 0.2 μm, and a phenomenon in which the etching rate is greatly different (finished thicker) is observed in a fine isopattern of 0.4 μm or less.

  On the other hand, it was predicted that this density dependence strongly correlated with the etching conditions, and a transition metal silicide light shielding film was tested as a light shielding film that can be processed under different etching conditions. As a photomask blank model for an ArF exposure mask, a MoSiN light-shielding film (Mo: Si: N = 1: 3: 1.5 (atomic ratio)) having a film thickness of 23 nm and a MoSiN antireflection film having a film thickness of 18 nm on a transparent substrate. (The composition on the light shielding film side is Mo: Si: N = 1: 3: 1.5 (atomic ratio), and the composition on the side away from the transparent substrate is Mo: Si: N = 1: 5: 5 (atomic ratio). And a pattern having a line width from 1.6 μm to 0.2 μm every 0.1 μm is prepared on the photomask blank, and the composition is inclined in the thickness direction). As a dense model, a 1: 9 line and space (iso pattern model) and a 9: 1 line and space (iso space model) were formed by fluorine-based dry etching.

  As a result, in the isospace, the size error between 1.6 μm and 0.2 μm is 2.3 nm in the width between the minimum value and the maximum value, whereas in the isopattern, it is between 1.6 μm and 0.2 μm. The width at 9.0 was 9.0 nm, and the problem of dependence on density was greatly improved.

[Experimental Example 2] Chromium content and etching resistance in chromium-based materials In order to investigate the etching resistance of chromium-based materials, metallic chromium was used as a target, argon, nitrogen, and oxygen gas were used as sputtering gases. By changing the flow rate, a chromium-based material film in which the ratio of chromium, oxygen, and nitrogen was changed was formed on the substrate. When this chromium-based material film was dry-etched with chlorine gas to examine the relationship between the amount of chromium in the film and the etching rate, the result shown in FIG. 11 was obtained. From this, it was found that if the chromium content in the chromium-based material film is 50 atomic% or more, the etching resistance is good.

Example 1 CrN / MoSiN / MoSiN / Substrate A light-shielding film (41 nm thick) made of molybdenum, silicon, and nitrogen was formed using a DC sputtering apparatus in which two targets were provided on a quartz substrate. Ar and nitrogen were used as the sputtering gas, and the gas pressure in the chamber was adjusted to 0.05 Pa. As the target, two kinds of targets were used, a Mo target as the transition metal source and a Si (single crystal) target as the silicon source, and the film was formed while rotating the substrate at 30 rpm. When the composition of this light shielding film was examined by ESCA, it was Mo: Si: N = 1: 3: 1.5 (atomic ratio).

  An antireflection film (film thickness: 18 nm) having a composition gradient in the thickness direction composed of molybdenum, silicon, and nitrogen was formed using a DC sputtering apparatus in which two targets were provided on the light shielding film. Ar and nitrogen were used as the sputtering gas, and the gas pressure in the chamber was adjusted to 0.05 Pa. As the target, two kinds of targets were used, a Mo target as the transition metal source and a Si (single crystal) target as the silicon source, and the film was formed while rotating the substrate at 30 rpm. When the composition of the antireflection film was examined by ESCA, the composition on the light shielding film side was Mo: Si: N = 1: 3: 1.5 (atomic ratio), and the composition on the side away from the transparent substrate (etching mask film side). Was Mo: Si: N = 1: 5: 5 (atomic ratio).

  An etching mask film (thickness 10 nm) made of CrN was formed on the antireflection film by using a DC sputtering apparatus. Ar and nitrogen were used as the sputtering gas, and the gas pressure in the chamber was adjusted to 0.05 Pa. As a target, Cr was used, and the film was formed while rotating the substrate at 30 rpm. When the composition of this etching mask film was examined by ESCA, it was Cr: N = 9: 1 (atomic ratio).

  Thus, a photomask blank was obtained in which a light shielding film made of MoSiN, an antireflection film made of MoSiN, and an etching mask film made of CrN were laminated on a quartz substrate.

  Next, an EB resist was applied as a resist on the etching mask film, and the resist was patterned by exposure and development. Next, dry etching was performed using a resist as a mask and a mixed gas of chlorine and oxygen as an etching gas, and the etching mask film was patterned. Next, using the resist and the etching mask film as a mask, the antireflection film and the light shielding film were subjected to fluorine-based dry etching and patterned. Thereafter, the resist was peeled off, and the etching mask film was removed by dry etching with a mixed gas of chlorine and oxygen, thereby completing a photomask from which the etching mask film was removed. As a result, a photomask in which the set pattern size was reflected well regardless of the density of the pattern was obtained, and it was found that this photomask blank had a small density dependency.

Example 2 CrON / CrN / MoSiN / Substrate A light-shielding film (thickness 30 nm) made of molybdenum, silicon, and nitrogen was formed using a DC sputtering apparatus in which two targets were provided on a quartz substrate. Ar and nitrogen were used as the sputtering gas, and the gas pressure in the chamber was adjusted to 0.05 Pa. As the target, two kinds of targets were used, a Mo target as the transition metal source and a Si (single crystal) target as the silicon source, and the film was formed while rotating the substrate at 30 rpm. When the composition of this light shielding film was examined by ESCA, it was Mo: Si: N = 1: 3: 1.5 (atomic ratio).

  An etching mask film (thickness 10 nm) made of CrN was formed on the light shielding film using a DC sputtering apparatus. Ar and nitrogen were used as the sputtering gas, and the gas pressure in the chamber was adjusted to 0.05 Pa. As a target, Cr was used, and the film was formed while rotating the substrate at 30 rpm. When the composition of this etching mask film was examined by ESCA, it was Cr: N = 9: 1 (atomic ratio).

  An antireflection film (thickness 20 nm) made of CrON was formed on the etching mask film using a DC sputtering apparatus. Ar, oxygen, and nitrogen were used as the sputtering gas, and the gas pressure in the chamber was adjusted to 0.05 Pa. As a target, Cr was used, and the film was formed while rotating the substrate at 30 rpm. When the composition of this antireflection film was examined by ESCA, it was Cr: O: N = 4: 5: 1 (atomic ratio).

  Thus, a photomask blank was obtained in which a light shielding film made of MoSiN, an etching mask film made of CrN, and an antireflection film made of CrON were laminated on a quartz substrate.

  Next, an EB resist was applied as a resist on the antireflection film, and the resist was patterned by exposure and development. Next, dry etching was performed using a resist as a mask and a mixed gas of chlorine and oxygen as an etching gas, and the antireflection film and the etching mask film were patterned. Next, using the resist, the antireflection film, and the etching mask film as a mask, the light shielding film was subjected to fluorine-based dry etching and patterned. Thereafter, the resist was peeled off to complete a photomask in which the etching mask film remained. As a result, a photomask in which the set pattern size was reflected well regardless of the density of the pattern was obtained, and it was found that this photomask blank had a small density dependency.

Example 3 CrON / MoSiN / MoSiN / Substrate Using a DC sputtering apparatus in which two targets were provided on a quartz substrate, a light-shielding film (thickness 41 nm) made of molybdenum, silicon, and nitrogen was formed. Ar and nitrogen were used as the sputtering gas, and the gas pressure in the chamber was adjusted to 0.05 Pa. As the target, two kinds of targets were used, a Mo target as the transition metal source and a Si (single crystal) target as the silicon source, and the film was formed while rotating the substrate at 30 rpm. When the composition of this light shielding film was examined by ESCA, it was Mo: Si: N = 1: 3: 1.5 (atomic ratio).

  An antireflection film (film thickness: 10 nm) made of molybdenum, silicon, and nitrogen was formed using a DC sputtering apparatus in which two targets were provided on the light shielding film. Ar and nitrogen were used as the sputtering gas, and the gas pressure in the chamber was adjusted to 0.05 Pa. As the target, two kinds of targets were used, a Mo target as the transition metal source and a Si (single crystal) target as the silicon source, and the film was formed while rotating the substrate at 30 rpm. When the composition of this antireflection film was examined by ESCA, it was Mo: Si: N = 1: 4: 3 (atomic ratio).

  An etching mask film (thickness: 10 nm) made of CrON was formed on the antireflection film using a direct current sputtering apparatus. Ar, oxygen, and nitrogen were used as the sputtering gas, and the gas pressure in the chamber was adjusted to 0.05 Pa. As a target, Cr was used, and the film was formed while rotating the substrate at 30 rpm. When the composition of this etching mask film was examined by ESCA, it was Cr: O: N = 4: 5: 1 (atomic ratio).

  Thus, a photomask blank was obtained in which a light shielding film made of MoSiN, an antireflection film made of MoSiN, and an etching mask film made of CrON were laminated on a quartz substrate.

  Next, an EB resist was applied as a resist on the etching mask film, and the resist was patterned by exposure and development. Next, dry etching was performed using a resist as a mask and a mixed gas of chlorine and oxygen as an etching gas, and the etching mask film was patterned. Next, using the resist and the etching mask film as a mask, the antireflection film and the light shielding film were subjected to fluorine-based dry etching and patterned. Thereafter, the resist was removed, and a photomask from which the etching mask film was removed was completed. As a result, a photomask in which the set pattern size was reflected well regardless of the density of the pattern was obtained, and it was found that this photomask blank had a small density dependency.

Example 4 Ta / MoSiN / MoSiN / Substrate A light-shielding film (thickness: 41 nm) made of molybdenum, silicon, and nitrogen was formed using a DC sputtering apparatus in which two targets were provided on a quartz substrate. Ar and nitrogen were used as the sputtering gas, and the gas pressure in the chamber was adjusted to 0.05 Pa. As the target, two kinds of targets were used, a Mo target as the transition metal source and a Si (single crystal) target as the silicon source, and the film was formed while rotating the substrate at 30 rpm. When the composition of this light shielding film was examined by ESCA, it was Mo: Si: N = 1: 3: 1.5 (atomic ratio).

  An antireflection film (film thickness: 18 nm) having a composition gradient in the thickness direction composed of molybdenum, silicon, and nitrogen was formed using a DC sputtering apparatus in which two targets were provided on the light shielding film. Ar and nitrogen were used as the sputtering gas, and the gas pressure in the chamber was adjusted to 0.05 Pa. As the target, two kinds of targets were used, a Mo target as the transition metal source and a Si (single crystal) target as the silicon source, and the film was formed while rotating the substrate at 30 rpm. When the composition of the antireflection film was examined by ESCA, the composition on the light shielding film side was Mo: Si: N = 1: 3: 1.5 (atomic ratio), and the composition on the side away from the transparent substrate (etching mask film side). Was Mo: Si: N = 1: 5: 5 (atomic ratio).

  An etching mask film (thickness: 15 nm) made of Ta was formed on the antireflection film using a DC sputtering apparatus. Ar was used as the sputtering gas, and the gas pressure in the chamber was adjusted to 0.05 Pa. Ta was used as a target, and the film was formed while rotating the substrate at 30 rpm.

  Thus, a photomask blank was obtained in which a light shielding film made of MoSiN, an antireflection film made of MoSiN, and an etching mask film made of Ta were laminated on a quartz substrate.

  Next, an EB resist was applied as a resist on the etching mask film, and the resist was patterned by exposure and development. Next, dry etching was performed using a resist as a mask and a mixed gas of chlorine and oxygen as an etching gas, and the etching mask film was patterned. Next, using the resist and the etching mask film as a mask, the antireflection film and the light shielding film were subjected to fluorine-based dry etching and patterned. Thereafter, the resist was peeled off, and the etching mask film was removed by dry etching with a mixed gas of chlorine and oxygen, thereby completing a photomask from which the etching mask film was removed. As a result, a photomask in which the set pattern size was reflected well regardless of the density of the pattern was obtained, and it was found that this photomask blank had a small density dependency.

[Example 5] CrON / CrN / MoSiN / substrate Levenson-type mask In the same manner as in Example 2, a light shielding film made of MoSiN, an etching mask film made of CrN, and an antireflection film made of CrON were laminated on a quartz substrate. A photomask blank was obtained.

  An EB resist was applied as a first resist on the antireflection film of the photomask blank, and the first resist was patterned by performing exposure and development. Next, dry etching was performed using the first resist as a mask and a mixed gas of chlorine and oxygen as an etching gas, and the antireflection film and the etching mask film were patterned. Next, using the first resist, the antireflection film, and the etching mask film as a mask, the light shielding film was subjected to fluorine-based dry etching and patterned, and then the first resist was peeled off. Next, an EB resist was applied as a second resist, and exposure and development were performed to form a second resist pattern from which a portion for etching the quartz substrate was removed. The quartz substrate was dry-etched with fluorine gas using the second resist, the antireflection film, and the etching mask film as a mask. Thereafter, the second resist was peeled off to complete a Levenson-type mask with an etching mask film remaining. As a result, a photomask in which the set pattern size was reflected well regardless of the density of the pattern was obtained, and it was found that this photomask blank had a small density dependency.

[Example 6] (CrON / CrN) / MoSiN / MoSiN / substrate Levenson-type mask Using a DC sputtering apparatus in which two targets are provided on a quartz substrate, a light-shielding film (film thickness) made of molybdenum, silicon, and nitrogen 41 nm) was deposited. Ar and nitrogen were used as the sputtering gas, and the gas pressure in the chamber was adjusted to 0.05 Pa. As the target, two kinds of targets were used, a Mo target as the transition metal source and a Si (single crystal) target as the silicon source, and the film was formed while rotating the substrate at 30 rpm. When the composition of this light shielding film was examined by ESCA, it was Mo: Si: N = 1: 3: 1.5 (atomic ratio).

  An antireflection film (film thickness: 18 nm) having a composition gradient in the thickness direction composed of molybdenum, silicon, and nitrogen was formed using a DC sputtering apparatus in which two targets were provided on the light shielding film. Ar and nitrogen were used as the sputtering gas, and the gas pressure in the chamber was adjusted to 0.05 Pa. As the target, two kinds of targets were used, a Mo target as the transition metal source and a Si (single crystal) target as the silicon source, and the film was formed while rotating the substrate at 30 rpm. When the composition of the antireflection film was examined by ESCA, the composition on the light shielding film side was Mo: Si: N = 1: 3: 1.5 (atomic ratio), and the composition on the side away from the transparent substrate (etching mask film side). Was Mo: Si: N = 1: 5: 5 (atomic ratio).

  On this antireflection film, an etching mask film (thickness 15 nm (CrN inner layer 10 nm, CrON front layer 5 nm) consisting of an inner layer made of CrN and a front side layer made of CrON was formed using a DC sputtering apparatus. As the sputtering gas, Ar and nitrogen were used for forming the inner layer, Ar, oxygen and nitrogen were used for forming the front side layer, and the gas pressure in the chamber was adjusted to 0.05 Pa. Cr was used as the target. When the composition of the etching mask film was examined by ESCA, the inner layer was Cr: N = 9: 1 (atomic ratio), and the front layer was Cr: O: N = 4: It was 5: 1 (atomic ratio).

  Thus, a photomask blank was obtained in which a light shielding film made of MoSiN, an antireflection film made of MoSiN, and an etching mask film made of two layers of CrON and CrN were laminated on a quartz substrate.

  An EB resist was applied as a first resist on the etching mask film of the photomask blank, and the first resist was patterned by performing exposure and development. Next, using the first resist as a mask, dry etching was performed using a mixed gas of chlorine and oxygen as an etching gas, and an etching mask film composed of a front side layer made of CrON and an inner layer made of CrN was patterned. Next, using the first resist and the etching mask film as a mask, the antireflection film and the light shielding film were subjected to fluorine-based dry etching and patterned, and then the first resist was peeled off. Next, an EB resist was applied as a second resist, and exposure and development were performed to form a second resist pattern from which a portion for etching the quartz substrate was removed. Using this second resist and the etching mask film as a mask, the quartz substrate was dry-etched with fluorine gas. After that, the second resist was peeled off, and the etching mask film was peeled off by dry etching using chlorine gas, thereby completing a Levenson type mask from which the etching mask film was removed. As a result, a photomask in which the set pattern size was reflected well regardless of the density of the pattern was obtained, and it was found that this photomask blank had a small density dependency.

Example 7 CrN / MoSiN / MoSi / MoSiON / Substrate Halftone Phase Shift Mask Halftone phase consisting of molybdenum, silicon, oxygen, and nitrogen using a DC sputtering apparatus having two targets on a quartz substrate. A shift film (film thickness 75 nm) was formed. Ar, oxygen, and nitrogen were used as the sputtering gas, and the gas pressure in the chamber was adjusted to 0.05 Pa. As the target, two kinds of targets were used, a Mo target as the transition metal source and a Si (single crystal) target as the silicon source, and the film was formed while rotating the substrate at 30 rpm. When the composition of this halftone phase shift film was examined by ESCA, it was Mo: Si: O: N = 1: 4: 1: 4 (atomic ratio).

  A light-shielding film (thickness: 23 nm) made of molybdenum and silicon was formed using a DC sputtering apparatus in which two targets were provided on the halftone phase shift film. Ar was used as the sputtering gas, and the gas pressure in the chamber was adjusted to 0.05 Pa. As the target, two kinds of targets were used, a Mo target as the transition metal source and a Si (single crystal) target as the silicon source, and the film was formed while rotating the substrate at 30 rpm. When the composition of this light shielding film was examined by ESCA, it was Mo: Si = 1: 5 (atomic ratio).

  An antireflection film (thickness 13 nm) made of molybdenum, silicon, and nitrogen was formed using a DC sputtering apparatus in which two targets were provided on the light shielding film. Ar and nitrogen were used as the sputtering gas, and the gas pressure in the chamber was adjusted to 0.05 Pa. As the target, two kinds of targets were used, a Mo target as the transition metal source and a Si (single crystal) target as the silicon source, and the film was formed while rotating the substrate at 30 rpm. When the composition of this antireflection film was examined by ESCA, it was Mo: Si: N = 1: 1: 2 (atomic ratio).

  An etching mask film (thickness 10 nm) made of CrN was formed on the antireflection film by using a DC sputtering apparatus. Ar and nitrogen were used as the sputtering gas, and the gas pressure in the chamber was adjusted to 0.05 Pa. As a target, Cr was used, and the film was formed while rotating the substrate at 30 rpm. When the composition of this etching mask film was examined by ESCA, it was Cr: N = 9: 1 (atomic ratio).

  Thus, a photomask blank was obtained in which a halftone phase shift film made of MoSiON, a light shielding film made of MoSi, an antireflection film made of MoSiN, and an etching mask film made of CrN were laminated on a quartz substrate.

  Next, a resist was patterned by applying a chemically amplified negative resist mainly composed of a hydroxystyrene-based resin, a crosslinking agent, and an acid generator as a resist to a film thickness of 250 nm, and performing exposure and development. Next, dry etching was performed using a resist as a mask and a mixed gas of chlorine and oxygen as an etching gas, and the etching mask film was patterned. Next, using the resist and the etching mask film as a mask, the antireflection film, the light shielding film, and the halftone phase shift film were subjected to fluorine-type dry etching and patterned. Thereafter, the resist was peeled off, and the etching mask film was removed by dry etching with a mixed gas of chlorine and oxygen to remove the etching mask film. Further, in order to remove unnecessary portions of the light shielding film, a resist pattern for protecting the portion where the light shielding film remains is formed, dry etching is performed with chlorine gas not containing oxygen, and after removing the antireflection film and the light shielding film, the resist is removed. Was removed to complete a halftone phase shift mask. As a result, there was obtained a photomask in which the pattern was not thinned and the set pattern size was reflected well regardless of the pattern density, and it was found that this photomask blank had a small density dependency.

DESCRIPTION OF SYMBOLS 1 Transparent substrate 2 Light-shielding film 3 Antireflection film 4 Etching mask film 5 Resist 6 First resist 7 Second resist 8 Phase shift film

Claims (19)

In photolithography for forming a resist pattern of 0.1 μm or less using light having an exposure wavelength of 250 nm or less provided with a mask pattern having a region transparent to exposure light and an effective opaque region on a transparent substrate A method of manufacturing a photomask to be used,
A light-shielding film made of a metal or a metal compound, which can be etched by fluorine-based dry etching, laminated on a transparent substrate with or without another film;
An antireflection film made of a metal or a metal compound that can be etched by fluorine-based dry etching formed on the light shielding film;
An etching mask film made of a metal or a metal compound having resistance to fluorine-based dry etching formed on the antireflection film;
Using a photomask blank in which the thickness of the etching mask film is 2 to 30 nm,
After applying a resist to the photomask blank and patterning the resist, the etching mask film is patterned by performing chlorine-based dry etching,
Using the etching mask film as a mask, the antireflection film and the light shielding film are subjected to fluorine-based dry etching and patterned,
Strip the resist,
A method for manufacturing a photomask, comprising removing the etching mask film by chlorine-based dry etching.   The light shielding film contains a transition metal and silicon, the ratio of transition metal to silicon (atomic ratio) is transition metal: silicon = 1: 4 to 1:15, and the transition metal content is 1 atom% or more and 20 The method for producing a photomask according to claim 1, wherein the amount is at most atomic%.   2. The method for producing a photomask according to claim 1, wherein the light-shielding film is a transition metal silicon compound containing a transition metal, silicon, and nitrogen and having a nitrogen content of 5 atomic% to 40 atomic%.   The transition metal silicon compound has a transition metal / silicon ratio (atomic ratio) of transition metal: silicon = 1: 1 to 1:10 and a transition metal content of 1 atomic% to 20 atomic%. The method of manufacturing a photomask according to claim 3.   The transition metal silicon compound constituting the light shielding film is selected from transition metal silicon nitride, transition metal silicon oxynitride, transition metal silicon oxynitride carbide, and transition metal silicon oxynitride carbide. The manufacturing method of the photomask as described.   6. The method of manufacturing a photomask according to claim 1, wherein the light shielding film has a thickness of 10 to 80 nm.   7. The method of manufacturing a photomask according to claim 1, wherein the antireflection film contains the same metal as that contained in the light shielding film.   8. The method for producing a photomask according to claim 7, wherein the antireflection film comprises a transition metal silicon compound containing a transition metal, silicon, and one or more selected from oxygen, nitrogen, and carbon.   The composition of the transition metal silicon compound that constitutes the antireflection film is such that silicon is 10 atomic% to 50 atomic%, oxygen is 0 atomic% to 60 atomic%, nitrogen is 20 atomic% to 50 atomic%, and carbon is 9. The method for producing a photomask according to claim 8, wherein the atomic ratio is 0 atomic% to 20 atomic%, and the transition metal is 1 atomic% to 35 atomic%.   The photomask manufacturing method according to any one of claims 1 to 9, wherein a fluorine-based dry etching selection ratio of the light shielding film to the etching mask film is 2 or more.   11. The photomask according to claim 1, wherein the etching mask film is made of chromium alone, or a chromium compound containing chromium and at least one selected from oxygen, nitrogen, and carbon. Manufacturing method.   12. The method of manufacturing a photomask according to claim 11, wherein the chromium compound has a chromium content of 50 atomic% or more.   11. The method of manufacturing a photomask according to claim 1, wherein the etching mask film is made of tantalum alone or a tantalum compound containing tantalum and not containing silicon.   11. The photo according to claim 1, wherein the etching mask film is a film containing chromium and not containing silicon, or a film containing tantalum and containing no silicon. Mask manufacturing method.   The photomask according to claim 1, wherein the transition metal is at least one selected from titanium, vanadium, cobalt, nickel, zirconium, niobium, molybdenum, hafnium, tantalum, and tungsten. Manufacturing method.   The method of manufacturing a photomask according to claim 1, wherein the transition metal is molybdenum.   The photomask manufacturing method according to any one of claims 1 to 16, wherein the other film is stacked via a phase shift film.   18. The method of manufacturing a photomask according to claim 17, wherein the phase shift film is a halftone phase shift film.   The photomask obtained by the manufacturing method of any one of Claims 1 thru | or 18.

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