JP2013178371A - Method for removing thin film of substrate with thin film, method for manufacturing transfer mask, method for regenerating substrate and method for manufacturing mask blank - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for removing a thin film of a substrate with thin films, capable of reducing damage to the substrate after removing the thin film and preventing a residue of the thin film.SOLUTION: By using a mask blank 10 having a light shielding film 2 made of a material including, for example, a molybdenum silicide compound and an etching mask film 3 made of a chromium based material which are formed on a translucent substrate 1 in this order, and patterning the thin films of the mask blank by a photolithography method, an etching mask film pattern 3a and a light shielding film pattern 2a are formed. After processing of making an ozone gas with high concentration of 100 volume% act on (for example, contact) the etching mask film pattern 3a while heating the substrate at 100°C or more, the etching mask film pattern 3a is peeled and removed.

Description

  The present invention relates to a method for removing a thin film from a substrate with a thin film, a method for manufacturing a transfer mask including a thin film removing step, a method for regenerating a substrate by removing a thin film such as a mask blank and regenerating the substrate, and a regenerated substrate The present invention relates to a mask blank manufacturing method using

 In general, in a manufacturing process of a semiconductor device, a fine pattern is formed using a photolithography method. Also, a number of transfer masks, usually called photomasks, are used to form this fine pattern. This transfer mask is generally provided with a fine pattern made of a metal thin film on a translucent glass substrate, and the photolithographic method is also used in the production of this transfer mask.

 In manufacturing a transfer mask by photolithography, a mask blank having a thin film (for example, a light shielding film) for forming a transfer pattern (mask pattern) on a light-transmitting substrate such as a glass substrate is used. The production of a transfer mask using the mask blank includes a drawing process for drawing a desired pattern on the resist film formed on the mask blank, and developing the resist film after drawing to form a desired resist pattern. The developing process is formed, the etching process is performed to etch the thin film using the resist pattern as a mask, and the process is performed to peel and remove the remaining resist pattern. In the developing step, a desired pattern is drawn on the resist film formed on the mask blank, and then a developing solution is supplied to dissolve a portion of the resist film that is soluble in the developing solution, thereby forming a resist pattern. . In the etching step, the resist pattern is used as a mask to remove the exposed portion of the thin film on which the resist pattern is not formed by dry etching or wet etching, thereby forming a desired mask pattern on the translucent substrate. Form. Thus, a transfer mask is completed.

  As a type of transfer mask, a halftone phase shift mask is known in addition to a binary mask having a light-shielding film pattern made of a chromium-based material on a conventional translucent substrate. This halftone type phase shift mask has a structure having a phase shift film on a translucent substrate, and this phase shift film has a light intensity that does not substantially contribute to exposure (for example, 1 for the exposure wavelength). % To 20%) and has a predetermined phase difference. For example, a material containing a molybdenum silicide compound is used. In addition, binary masks using a material containing a metal silicide compound such as molybdenum or a material containing tantalum as a light-shielding film have been used.

  By the way, a method using an etching mask film is known as a method for reducing the thickness of a resist film which is effective in realizing miniaturization of a mask pattern (for example, JP-A-2006-146152). For example, a mask blank in which an etching mask film formed of a material having a different etching characteristic (etching selectivity) from the light shielding film is provided on the surface of the light shielding film on the translucent substrate. The etching mask film is etched using the resist pattern formed above as a mask to form a pattern, and then the light shielding film is etched using the pattern of the etching mask film as a mask to form a light shielding film pattern.

Depending on the material of the light shielding film, for example, the chromium etching mask film pattern remaining on the molybdenum silicide light shielding film pattern is finally removed.
Further, also in the manufacturing process of the imprint mold used for manufacturing the optical component, the substrate digging pattern formed for digging the glass substrate is finally removed.

  As a method for removing the thin film pattern, conventionally, a method using a thin film etchant is generally used. For example, in the case of a thin film pattern of a chromium-based material, wet etching using a ceric ammonium nitrate solution, or chlorine and oxygen This gas was removed by dry etching using an etching gas as an etching gas. Patent Document 1 describes that a chromium-based etching mask film on a molybdenum silicide-based light-shielding film is removed by dry etching using a mixed gas of chlorine and oxygen, and Patent Document 2 discloses a molybdenum silicide-based half film. It describes that the chromium-based light-shielding film on the tone material film is removed by wet etching with a ceric ammonium nitrate solution.

JP 2007-2441060 A JP 2003-195479 A

  However, in the case of the conventional method using the thin film etchant, the lower layer film after removal of the thin film (for example, the above-described molybdenum silicide-based light-shielding film or molybdenum silicide-based halftone material film) in both wet etching and dry etching methods. It is inevitable that damages such as an increase in surface roughness and changes in optical characteristics (optical density, reflectance, transmittance, phase difference, etc.) will occur. In transfer masks, such deterioration of surface roughness and changes in optical characteristics are important issues that affect mask performance. Ultimately, the quality of semiconductor devices manufactured using transfer masks is reduced. It will make it worse. In this case, it is possible to suppress the occurrence of damage by making the etching conditions for removing the thin film as loose as possible, but if the etching conditions are made loose, there is a new problem that etching residues of the thin film remain. Occur.

  In addition, competition for lower prices of electronic parts such as semiconductor devices in recent years has become severe, and it is also an important issue to suppress the manufacturing cost of a transfer mask. Against this background, after forming a thin film for pattern formation on a substrate, a mask defect in which a surface defect was found or a pattern defect that was difficult to correct was found in a transfer mask made using the mask blank. There is a demand for a method of reclaiming a substrate by peeling off and removing the thin film from the substrate without discarding the transferred mask as a defective product.

  In this case as well, it is possible to use a method of peeling and removing using a thin film etchant. For example, an altered layer is formed on the surface of the substrate after the thin film is removed, or the surface of the substrate that has been polished highly smoothly is used. It is required that damage such as an increase in surface roughness does not occur. In order to regenerate a substrate on which such damage has occurred, it is necessary to re-polish and take a lot of polishing allowance. Surface polishing of a glass substrate before film formation is usually performed through a plurality of stages of polishing steps from rough polishing to precision polishing. When re-polishing, since it is necessary to take a lot of polishing allowance as described above, it is necessary to return to the initial stage of the multi-step polishing process, and the re-polishing process takes a long time, so the re-polishing process load Is large and the cost is high. In recent years, with the miniaturization of patterns in semiconductor devices and the like, high-precision and high-quality transfer masks are required, and mask blanks for manufacturing such transfer masks are expensive with high added value. Substrates are increasingly used, and in order to reduce the manufacturing cost of a transfer mask, the regeneration of the mask blank substrate has become more important than ever.

 Therefore, the present invention has been made in view of such a conventional problem. The object of the present invention is, firstly, a substrate with a thin film in which there is little damage to the substrate after the thin film is removed and no thin film residue remains. And second, to provide a method for manufacturing a transfer mask including a step of removing a thin film in which the lower layer film is less damaged after the thin film is removed and no thin film residue remains. And third, to provide a method for regenerating a substrate that can reduce the cost of regenerating the substrate by reducing the damage to the substrate after removing the thin film and reducing the process load of re-polishing, and fourth, It is an object of the present invention to provide a mask blank manufacturing method and a transfer mask manufacturing method using a substrate regenerated by this regenerating method.

  As a result of diligent studies to solve the above problems, the present inventor made ozone gas act on the thin film while heating the thin film-formed substrate on which a thin film made of a material containing a metal or a compound thereof was formed. It has been found that by removing the thin film on the substrate, damage to the substrate and the lower layer film surface after the thin film removal can be reduced. Moreover, it has been found that all thin film residues can be removed.

The present inventor completed the present invention as a result of further intensive studies based on the above elucidated facts.
That is, in order to solve the above problems, the present invention has the following configuration.
(Configuration 1)
A method for removing a thin film from a substrate with a thin film in which a thin film made of a material containing a metal or a compound thereof is formed on the substrate, wherein the thin film is formed by applying ozone gas to the thin film while heating the substrate with the thin film. A method for removing a thin film from a substrate with a thin film, comprising: removing the thin film.

(Configuration 2)
2. The method for removing a thin film from a substrate with a thin film according to Configuration 1, wherein the metal forms an oxide having a low melting point by applying ozone gas.
(Configuration 3)
The method for removing a thin film from a substrate with a thin film according to Configuration 2, wherein the metal is chromium (Cr).

(Configuration 4)
4. The method for removing a thin film from a substrate with a thin film according to any one of Structures 1 to 3, wherein the concentration of ozone gas is 50 to 100% by volume.
(Configuration 5)
The method for removing a thin film from a substrate with a thin film according to any one of Structures 1 to 4, wherein the heating temperature of the substrate with a thin film is 100 ° C. or higher.

(Configuration 6)
A method for manufacturing a transfer mask having a mask pattern for forming a transfer pattern on or on a substrate, comprising a mask pattern for forming a transfer pattern on a substrate or on a substrate and a metal or a compound thereof A step of producing a substrate with a pattern in which a thin film pattern made of a material is sequentially formed, and a step of removing the thin film pattern, wherein the thin film pattern is heated while heating the substrate with a pattern. A method for producing a transfer mask, wherein ozone gas is allowed to act on the thin film pattern to remove the thin film pattern.

(Configuration 7)
7. The method for manufacturing a transfer mask according to Configuration 6, wherein the metal forms an oxide having a low melting point by applying ozone gas.
(Configuration 8)
8. The method for manufacturing a transfer mask according to Configuration 7, wherein the metal is chromium (Cr).

(Configuration 9)
9. The method for manufacturing a transfer mask according to any one of configurations 6 to 8, wherein the concentration of ozone gas is 50 to 100% by volume.
(Configuration 10)
10. The method for manufacturing a transfer mask according to any one of configurations 6 to 9, wherein the heating temperature of the substrate with a pattern is 100 ° C. or higher.

(Configuration 11)
The method for manufacturing a transfer mask according to any one of Structures 6 to 10, wherein a resist pattern is formed on the thin film pattern, and the resist pattern and the thin film pattern are removed in the removing step.
(Configuration 12)
12. The transfer mask according to Configuration 11, wherein in the removing step, ozone gas and unsaturated hydrocarbon gas are allowed to act on the resist pattern and the thin film pattern to remove the resist pattern and the thin film pattern. Production method.

(Configuration 13)
A method of regenerating a substrate by removing the thin film of a mask blank provided with a thin film made of a material containing a metal for pattern formation or a compound thereof on the substrate or a transfer mask prepared using the mask blank, A method for reclaiming a substrate, comprising removing the thin film by applying ozone gas to the thin film while heating the mask blank or the transfer mask.
(Configuration 14)
A method of regenerating a substrate by removing the thin film of a mask blank comprising a laminated film having a thin film formed of a material containing a metal or a compound on the surface of the substrate, and heating the mask blank, A method for regenerating a substrate, comprising removing the thin film by applying ozone gas to the thin film.

(Configuration 15)
15. The method for regenerating a substrate according to Configuration 13 or 14, wherein the metal forms an oxide having a low melting point by applying ozone gas.
(Configuration 16)
16. The method for regenerating a substrate according to Configuration 15, wherein the metal is chromium (Cr).

(Configuration 17)
The method for regenerating a substrate according to any one of Structures 13 to 16, wherein the concentration of ozone gas is 50 to 100% by volume.
(Configuration 18)
The method for regenerating a substrate according to any one of Structures 13 to 17, wherein a heating temperature of the mask blank or the transfer mask is 100 ° C. or higher.

(Configuration 19)
A method for manufacturing a mask blank, comprising: forming a thin film for pattern formation on a substrate regenerated by the method for regenerating a substrate according to any one of Structures 13 to 18.
(Configuration 20)
A method for producing a transfer mask, comprising: patterning the thin film in a mask blank obtained by the method for producing a mask blank according to Configuration 19 to form a thin film pattern on the substrate.

  According to the method for removing a thin film from a substrate with a thin film according to the present invention, while heating the thin film substrate on which a thin film made of a material containing a metal or a compound thereof is heated, ozone gas is allowed to act on the thin film, By removing the thin film, there is little damage to the substrate after the thin film is removed, and the thin film residue can be removed without remaining.

  Further, according to the method for manufacturing a transfer mask according to the present invention, a mask pattern for forming a transfer pattern and a thin film pattern made of a material containing a metal or a compound thereof are sequentially formed on the substrate. A step of producing a substrate; and a removing step of removing the thin film pattern. In the removing step, the thin film pattern is removed by applying ozone gas to the thin film pattern while heating the substrate with the pattern. The mask pattern of the lower layer film after the thin film is removed is less damaged and can be removed without leaving a thin film residue. As a result, a transfer mask with less surface roughness degradation and less change in optical properties can be obtained.

Further, according to the method for regenerating a substrate according to the present invention, a mask blank provided with a thin film made of a material containing a metal for forming a pattern or a compound thereof on the substrate or a transfer mask produced using the mask blank is heated. However, by removing the thin film by applying ozone gas to the thin film, the damage to the substrate after the thin film removal can be reduced, and the re-polishing process load is reduced, thereby reducing the cost of regenerating the substrate. can do. In addition, since a high-quality substrate can be reproduced at low cost in this manner, it is particularly suitable for regenerating a mask blank using an expensive base material having high added value.
Further, according to the present invention, a mask blank using a high-quality substrate regenerated by this regenerating method can be manufactured, and a transfer mask can be manufactured using this mask blank.

It is sectional drawing which shows the process of manufacturing the transfer mask by this invention in order.

Hereinafter, embodiments of the present invention will be described in detail.
[First Embodiment]
First, as a first embodiment of the present invention, a method of removing a thin film from a substrate with a thin film will be described.
That is, the present invention relates to a method for removing a thin film from a substrate with a thin film in which a thin film made of a material containing a metal or a compound thereof is formed on the substrate, wherein ozone gas is applied to the thin film while heating the substrate with the thin film. The thin film is removed from the substrate with the thin film, wherein the thin film is removed.
The method for removing a thin film from a substrate with a thin film according to the present invention includes, as will be described later, specifically, a transfer mask manufacturing method, an imprint mold manufacturing method, a substrate recycling method, and the like. It can be preferably applied to.

As the substrate, for example, a transfer mask or a mask blank serving as an original plate thereof may be a synthetic quartz substrate or other various glass substrates (for example, soda lime glass) as long as it is transparent to the exposure wavelength used. Among them, a synthetic quartz substrate is particularly preferably used because of its high transparency in an ArF excimer laser or a shorter wavelength region. In addition, in a substrate for a reflective mask or a reflective mask blank, a substrate having a low thermal expansion coefficient is preferably used in order to prevent distortion of the pattern due to heat during exposure. For example, if it is amorphous glass, SiO ₂ —TiO ₂ is used. _{In the case of two-} system glass, quartz glass, and crystallized glass, crystallized glass or the like in which a β quartz solid solution is precipitated can be used.

  For example, in the production of a transfer mask, the thin film is a thin film used for forming a pattern of a transfer mask. In the present invention, a thin film made of a material containing a metal or a compound thereof is preferably used.

  The method for removing a thin film from a substrate with a thin film according to the present invention is characterized by removing the thin film by applying ozone gas to the thin film while heating the substrate with the thin film. Thus, by heating the substrate with a thin film and causing ozone gas to act on the thin film, a low-melting metal oxide can be formed and dissolved and removed. According to the inventor's consideration, a low melting point metal is formed before the passive state is formed by performing (supplying) the ozone gas on the thin film in a temperature atmosphere above a certain level. It is considered that oxides are formed and sublimation proceeds.

Therefore, it is preferable in the present invention that the metal contained in the material constituting the thin film is one that forms a low melting point oxide by the action of ozone gas. The low melting point is a range of about 300 ° C. or lower in a constant temperature and constant pressure state. Examples of the metal forming the low melting point oxide include chromium (Cr) and ruthenium (Ru). Among such metals, chromium (Cr) and ruthenium (Ru) are particularly suitable because they easily form oxides (CrO ₃ , RuO _4, etc.) having a low melting point (200 ° C. or less) by the action of ozone gas. It is. That is, the thin film removal method of the present invention is particularly effective when removing a thin film from a substrate with a thin film in which a thin film made of a material containing chromium metal or a compound thereof, ruthenium metal or a compound thereof is formed on the substrate. .
Examples of the chromium or ruthenium compound include those containing at least one element of oxygen, nitrogen, carbon, and hydrogen in addition to chromium and ruthenium.

  As a method of causing ozone gas to act on the thin film formed on the substrate, for example, a method in which a substrate with a thin film is installed in a suitable chamber, ozone gas is introduced into the chamber, and the inside of the chamber is replaced with ozone gas. It is done. Alternatively, a method of supplying ozone gas directly to the surface of the thin film may be used.

  In this invention, it is preferable that the density | concentration of the said ozone gas is high concentration ozone gas of the range of 50-100 volume%. If the concentration of ozone gas is less than 50% by volume, the treatment time may be very long, or even if the treatment time is lengthened, it may be difficult to remove the thin film without residue. . Moreover, in order to make processing time short, it is preferable that the density | concentration of ozone gas is 100 volume%. In addition, it is desirable to process under reduced pressure, so that the density | concentration of ozone gas is high. High-concentration ozone gas may not exist unless it is under reduced pressure. Usually, a reduced pressure within a range of about 200 Pa to 10 Pa is suitable.

Regarding the processing time (time for allowing ozone gas to act), it is basically sufficient that the thin film on the substrate can be peeled and removed without residue, but depending on the ozone gas concentration, the heating temperature of the substrate, etc. Since it is slightly different, it may be determined appropriately in consideration of the ozone gas concentration, the heating temperature of the substrate, and the like.
Further, the ozone gas treatment is performed while heating the substrate with the thin film. In this case, the heating temperature is 100 ° C. in order to further promote the reaction in which the low melting point metal oxide is formed. The above conditions are preferable. On the other hand, if the heating temperature in this case is too high, there is a risk of adverse effects such as deterioration on the substrate and the lower layer film (if any) under the thin film, so the upper limit of the heating temperature is preferably about 300 ° C. .

Further, it is preferable that the ozone gas is mixed with an unsaturated hydrocarbon gas to act. The unsaturated hydrocarbon gas in this case is a hydrocarbon having a carbon double bond (alkene) such as ethylene gas, a hydrocarbon having a carbon triple bond (alkyne) such as acetylene, or a low molecular weight one such as butylene. Is preferred. For example, hydrocarbon (alkene) having a carbon double bond such as ethylene and butylene, hydrocarbon (alkyne) having a carbon triple bond such as acetylene, and the like are mentioned. The lower unsaturated hydrocarbon gas is preferred.
The supply ratio (flow rate ratio) between ozone gas and unsaturated hydrocarbon gas is preferably 1: 1 to 4: 1. Particularly within this range, the thin film pattern is satisfactorily removed in a shorter time while suppressing the heating temperature of the substrate.

  According to the method for removing a thin film from a substrate with a thin film according to the present invention as described above, an ozone gas is applied to the thin film while heating the thin film substrate on which a thin film made of a material containing a metal or a compound thereof is formed on the substrate. By removing the thin film, it is possible to suppress the occurrence of damage such as deterioration (increase) of the surface roughness of the substrate after the thin film is removed. Moreover, according to the present invention, the thin film residue can be removed without remaining on the substrate.

As explained before, in the case of the conventional method using a thin film etchant, if etching is performed under the condition that no etching residue remains, damage such as deterioration of the surface roughness of the substrate after thin film removal occurs. It is inevitable to do. In this case, if the etching conditions are relaxed to suppress the occurrence of damage as much as possible, the thin film etching residue remains on the substrate.
Therefore, the method for removing a thin film of the present invention, which can remove the substrate after the thin film is removed and can be removed without leaving a thin film residue, is very useful.

[Second Embodiment]
Next, a transfer mask manufacturing method will be described as a second embodiment of the present invention.
That is, the present invention is a method for manufacturing a transfer mask having a mask pattern for forming a transfer pattern on a substrate or a substrate, the mask pattern for forming a transfer pattern on the substrate or the substrate, A step of producing a patterned substrate on which a thin film pattern made of a material containing a metal or a compound thereof is sequentially formed, and a removing step of removing the thin film pattern, wherein the substrate with pattern is heated in the removing step However, the transfer mask manufacturing method is characterized in that ozone gas is applied to the thin film pattern to remove the thin film pattern.

The transfer mask in the present embodiment has a mask pattern for forming a transfer pattern on the main surface of the substrate or by digging the substrate, but for manufacturing the transfer mask. Specifically, as the mask blank to be an original, specifically, a binary mask blank having a structure including a light shielding film on the main surface of the substrate, a structure including a phase shift film, or a phase shift film and a light shielding film on the main surface of the substrate. A phase shift mask blank, a substrate digging type phase shift mask blank having a light shielding film on the main surface of the substrate, a multilayer reflective film for reflecting exposure light on the main surface of the substrate, and absorbing the exposure light Examples include reflective mask blanks having a structure including an absorber film for pattern formation in order, and the present invention relates to these mask blanks or these mask blanks. It is preferably applied to the manufacture of the transfer mask using the mask blank structure with further etching mask film on the uppermost layer.
The light shielding film may be a single layer or a plurality of layers (for example, a laminated structure of a light shielding layer and an antireflection layer). Further, when the light shielding film has a laminated structure of a light shielding layer and an antireflection layer, the light shielding layer may be composed of a plurality of layers. The phase shift film may be a single layer or a plurality of layers.

As the substrate, for example, a binary mask, a phase shift mask, or a mask blank serving as an original plate thereof may be a synthetic quartz substrate or any other glass substrate as long as it is transparent to the exposure wavelength used. For example, soda lime glass, aluminosilicate glass, etc.) are used. Among them, a synthetic quartz substrate is particularly preferably used because it has high transparency in an ArF excimer laser or a shorter wavelength region. Further, in the reflective mask or the reflective mask blank, those having a low thermal expansion coefficient are preferably used in order to prevent distortion of the pattern due to heat at the time of exposure. For example, if it is amorphous glass, SiO ₂ —TiO ₂ glass In the case of quartz glass or crystallized glass, crystallized glass in which β quartz solid solution is precipitated can be used.

The method for producing a transfer mask according to the present invention is a process for producing a patterned substrate in which a mask pattern for forming a transfer pattern and a thin film pattern made of a material containing a metal or a compound thereof are sequentially formed on the substrate. And a removing step for removing the thin film pattern. In this removing step, the thin film pattern is removed by applying ozone gas to the thin film pattern while heating the substrate with the pattern.
The mask pattern is, for example, a light shielding film pattern, a phase shift film pattern, an absorber film pattern, or the like. The thin film pattern is, for example, an etching mask film pattern, a light shielding film pattern on the phase shift film pattern, or the like.

  In this manner, by applying ozone gas to the thin film pattern while heating the substrate with the pattern, a metal oxide having a low melting point can be formed and the thin film pattern can be dissolved and removed. The mechanism of this reaction is as described in the first embodiment.

Also in this embodiment, it is preferable that the metal contained in the material constituting the thin film is a material that forms an oxide having a low melting point by the action of ozone gas. Among such metals, chromium (Cr) and ruthenium (Ru) are particularly suitable because they easily form oxides (CrO ₃ , RuO _4, etc.) having a low melting point (200 ° C. or less) by the action of ozone gas. It is.

  Examples of a method for causing ozone gas to act on the thin film pattern include a method in which the substrate with the pattern is placed in a suitable chamber, ozone gas is introduced into the chamber, and the inside of the chamber is replaced with ozone gas. Alternatively, a method of supplying ozone gas directly to the thin film pattern may be used.

  Also in this Embodiment, it is preferable that the density | concentration of the said ozone gas is high concentration ozone gas of the range of 50-100 volume%. If the concentration of ozone gas is less than 50% by volume, the treatment time may be very long, or even if the treatment time is lengthened, it may be difficult to remove the thin film without residue. . Moreover, in order to make processing time short, it is preferable that the density | concentration of ozone gas is 100 volume%. In addition, it is desirable to process under reduced pressure, so that the density | concentration of ozone gas is high. High-concentration ozone gas may not exist unless it is under reduced pressure. Usually, a reduced pressure within a range of about 200 Pa to 10 Pa is suitable.

  Regarding the processing time (time for allowing ozone gas to act), it is basically sufficient that the thin film on the substrate can be peeled and removed without residue, but depending on the ozone gas concentration, the heating temperature of the substrate, etc. Since it is slightly different, it may be determined appropriately in consideration of the ozone gas concentration, the heating temperature of the substrate, and the like.

  In addition, the ozone gas treatment is performed while heating the patterned substrate. In this case, the heating temperature is 100 ° C. in order to further promote the reaction for forming a low-melting metal oxide. Conditions that are at or above ° C are preferred. On the other hand, if the heating temperature in this case is too high, the lower layer film pattern under the substrate or the thin film pattern may be adversely affected such as deterioration. Therefore, the upper limit of the heating temperature is preferably about 300 ° C.

  As a material for forming the mask pattern, a material having etching resistance with respect to the material for forming the thin film pattern and capable of forming a passive film when the ozone gas treatment is performed is preferable. Such combinations include the following. A binary mask blank having a light shielding film made of a material containing a transition metal and silicon (Si) or a material containing tantalum (Ta), and a thin film of, for example, a chromium-based material as an etching mask film on the light shielding film. May be used. Further, a light-shielding band is formed on the phase shift film using a phase shift mask blank having a phase shift film made of a material containing silicon (Si) or a thin film made of a material containing a transition metal and silicon (Si). For example, a thin film of a chromium-based material may be used as the light shielding film for this purpose. The present invention provides a method for manufacturing a transfer mask comprising a step of removing the etching mask film (pattern) and the light shielding film (pattern) for forming a light shielding band when a transfer mask is manufactured using the mask blank. It can be particularly preferably applied.

  Examples of the material containing the transition metal and silicon (Si) include a material containing at least one element of nitrogen, oxygen and carbon in addition to the transition metal and silicon in addition to the material containing the transition metal and silicon. It is done. Specifically, a transition metal silicide or a material containing a transition metal silicide nitride, oxide, carbide, oxynitride, carbonate, or carbonitride is preferable. As the transition metal, molybdenum, tantalum, tungsten, titanium, hafnium, nickel, vanadium, zirconium, ruthenium, rhodium, niobium, and the like are applicable. Of these, molybdenum is particularly preferred.

The tantalum (Ta) -containing material includes, in addition to tantalum alone, a compound of tantalum and other metal elements (for example, Hf, Zr, etc.), tantalum, nitrogen, oxygen, carbon, and boron. A material containing at least one element, specifically, a material containing TaN, TaO, TaC, TaB, TaON, TaCN, TaBN, TaCO, TaBO, TaBC, TaCON, TaBON, TaBCN, TaBCON, or the like.
In addition, as the material containing silicon (Si), a material containing silicon and at least one element of nitrogen, oxygen, and carbon, specifically, silicon nitride, oxide, carbide, oxynitride A material containing a product, a carbonate, or a carbonitride is preferable.

  The present invention also provides a reflective mask using a reflective mask blank that includes an absorber film on a substrate with a multilayer reflective film, and further includes, for example, a thin film of a chromium-based material as an etching mask film on the absorber film. When manufacturing, the method can be preferably applied to a method for manufacturing a reflective mask including a step of removing the etching mask film (pattern).

  The multilayer reflective film is a multilayer film in which a low refractive index layer and a high refractive index layer are alternately laminated. In general, a thin film of a heavy element or a compound thereof and a thin film of a light element or a compound thereof are alternately arranged. In addition, a multilayer film laminated for about 40 to 60 periods is used. For example, as a multilayer reflective film for EUV light having a wavelength of 13 to 14 nm, a Mo / Si periodic laminated film in which Mo films and Si films are alternately laminated for about 40 cycles is preferably used. Other examples of multilayer reflective films used in the EUV light region include Mo / Be periodic multilayer films, Mo compound / Si compound periodic multilayer films, and Si / Nb periodic multilayer films. The material may be appropriately selected depending on the exposure wavelength.

  The absorber film has a function of absorbing exposure light such as EUV light. For example, tantalum (Ta) alone or a material mainly composed of Ta is preferably used. As a material having Ta as a main component, a material containing Ta and B, a material containing Ta and N, a material containing Ta and B and further containing at least one of O and N, a material containing Ta and Si, Ta A material containing Si and N, a material containing Ta and Ge, a material containing Ta, Ge and N are used.

FIG. 1 is a cross-sectional view sequentially illustrating steps of manufacturing a transfer mask according to the present invention. Here, a manufacturing example of a binary mask is shown.
In this example, a mask blank 10 (see FIG. 1A) in which a light shielding film 2 made of, for example, a material containing a molybdenum silicide compound and an etching mask film 3 made of a chromium-based material are sequentially formed on a translucent substrate 1. The thin film pattern is formed by patterning the thin film of the mask blank by photolithography. That is, for example, a positive resist film 4 for electron beam drawing is formed on the mask blank 10 (see FIG. 1A), and a desired device pattern is drawn on the resist film 4. After drawing, the resist film 4 is developed to form a resist pattern 4a (see FIG. 5B).

Next, using the resist pattern 4a as a mask, the chromium-based etching mask film 3 is etched by dry etching using a mixed gas of chlorine and oxygen to form an etching mask film pattern 3a (thin film pattern) (FIG. 5). (See (c)). The remaining resist pattern 4a is removed by ashing.
Next, using the etching mask film pattern 3a as a mask, the molybdenum silicide light shielding film 2 is etched by dry etching using a fluorine-based gas (for example, SF ₆ ) to form a light shielding film pattern 2a (mask pattern). (See (d) in the figure).

Next, according to the method of the present invention described above, the substrate on which the etching mask film pattern 3a and the light shielding film pattern 2a are formed is heated to, for example, 100 ° C. A process of applying high concentration ozone gas (for example, contact) is performed to peel and remove the etching mask film pattern 3a.
In this way, a transfer mask 20 in which the light shielding film pattern 2a is formed on the translucent substrate 1 is completed (see FIG. 5E).

  In the above manufacturing process, the case where the resist pattern 4a remaining after the etching mask film pattern 3a is formed has been described. However, the present invention is not limited to this. For example, when the etching mask film pattern 3a is removed, the etching mask film pattern 3a is removed. The resist pattern 4a on the film pattern 3a may be removed together.

When the resist pattern is also removed together in this way, it is preferable that the unsaturated hydrocarbon gas is mixed with the ozone gas to act. The unsaturated hydrocarbon gas in this case is a hydrocarbon having a carbon double bond (alkene) such as ethylene gas, a hydrocarbon having a carbon triple bond (alkyne) such as acetylene, or a low molecular weight one such as butylene. Is preferred. For example, hydrocarbon (alkene) having a carbon double bond such as ethylene and butylene, hydrocarbon (alkyne) having a carbon triple bond such as acetylene, and the like are mentioned. The lower unsaturated hydrocarbon gas is preferred.
The supply ratio (flow rate ratio) between ozone gas and unsaturated hydrocarbon gas is preferably 1: 1 to 4: 1. Particularly within this range, not only the thin film pattern but also the resist pattern thereon can be removed well.

  Further, although the purpose of use is different from the transfer mask as described above, in a mask blank provided with a thin film for forming a substrate digging pattern on the main surface of a substrate made of a glass material, the thin film and the above-mentioned film by dry etching treatment The present invention can also be applied to a method for producing an imprint mold in which the thin film (pattern) is removed after etching the substrate.

In the production of imprint molds (stampers) used for fine pattern formation of magnetic layers in magnetic recording media used in hard disk drives, etc. A mask blank provided with a thin film for forming a substrate digging pattern on a glass substrate such as synthetic quartz glass is used. A desired resist pattern is formed on the mask blank, the thin film is etched by using the resist pattern as a mask, and the substrate is etched by using the thin film pattern as a mask. An imprint mold is produced by forming a step pattern (mask pattern) on the optical substrate.
In the method of manufacturing an imprint mold, for example, the present invention preferably applies the removing step in the above-described transfer mask manufacturing method when the thin film pattern made of a chromium-based material is finally removed. .

As described above, according to the method for manufacturing a transfer mask according to the present invention, a mask pattern for forming a transfer pattern on a substrate or a substrate and a thin film pattern made of a material containing a metal or a compound thereof are provided. In the removal step of removing the thin film pattern after producing the substrate with the pattern formed in sequence, the thin film pattern is removed by removing the thin film pattern by applying ozone gas to the thin film pattern while heating the patterned substrate. There is little damage such as deterioration of the surface roughness of the subsequent underlayer film or the mask pattern of the substrate or changes in optical characteristics, and it can be removed without leaving a thin film residue. Thereby, a transfer mask can be obtained in which the surface roughness of the mask pattern at the time of mask fabrication is less deteriorated and the optical characteristics are less changed.
In addition, when removing the thin film pattern, an oxide film is formed on the surface (including side surfaces) of the mask pattern by ozone gas treatment, so that a transfer mask having excellent chemical resistance and light resistance can be obtained.

[Third Embodiment]
Next, as a third embodiment of the present invention, a substrate recycling method will be described.
That is, the present invention removes the thin film from a mask blank provided with a thin film made of a material containing a metal for forming a pattern or a compound for forming a pattern on the substrate, or the transfer mask produced using the mask blank, and regenerates the substrate. A method for regenerating a substrate, wherein the thin film is removed by applying ozone gas to the thin film while heating the mask blank or the transfer mask.

  Examples of the mask blank or transfer mask to which the substrate recycling method of the present invention is applied include a binary mask blank or a binary mask having a structure having a light shielding film on the main surface of the substrate. This is preferably applied when the substrate is regenerated by removing the light shielding film in the binary mask blank or the light shielding film pattern in the binary mask.

Further, as another aspect of the method for regenerating a substrate according to the present invention, the substrate is formed by removing the thin film of the mask blank provided with a laminated film on the surface of which a thin film made of a material containing a metal or a compound thereof is formed. A method for regenerating a substrate, wherein the thin film is removed by applying ozone gas to the thin film while heating the mask blank.
For example, the present invention removes only the etching mask film in a binary mask blank having a structure having a light shielding film on the main surface of the substrate and further having an etching mask film on the light shielding film. When regenerating a substrate provided, or when removing only the light shielding film in a phase shift mask blank having a structure including a phase shift film and a light shielding film on the main surface of the substrate and regenerating a substrate provided with the phase shift film Also preferably applied.

  The mask blank includes one having a resist film on the thin film. Furthermore, the mask blank includes those in the middle of producing a transfer mask, such as those having a resist pattern on a thin film and those having a resist pattern on a thin film pattern. Thus, when reproducing a mask blank provided with a resist film or a resist pattern, as in the second embodiment, an ozone gas and an unsaturated hydrocarbon gas are allowed to act to form a thin film (pattern) and a resist film. The (resist pattern) may be removed at the same time.

  The substrate recycling method of the present invention is characterized by removing the thin film by applying ozone gas to the thin film on the surface while heating the mask blank or the transfer mask. In this manner, by applying ozone gas to the thin film while heating the mask blank or the transfer mask, a low melting point metal oxide can be formed and the thin film can be dissolved and removed. The mechanism of this reaction is as described in the first embodiment.

Also in this embodiment, it is preferable that the metal contained in the material constituting the thin film such as the light shielding film or the etching mask film is one that forms an oxide having a low melting point by applying ozone gas. . Among such metals, chromium (Cr) and ruthenium (Ru) are particularly suitable because they easily form oxides (CrO ₃ , RuO _4, etc.) having a low melting point (200 ° C. or less) by the action of ozone gas. It is.

The method of causing ozone gas to act on the thin film formed on the substrate is the same as in the above-described embodiment.
Also in the present embodiment, the concentration of the ozone gas is preferably a high-concentration ozone gas in the range of 50 to 100% by volume. If the concentration of ozone gas is less than 50% by volume, the treatment time may be very long, or even if the treatment time is lengthened, it may be difficult to remove the thin film without residue. . Moreover, in order to make processing time short, it is preferable that the density | concentration of ozone gas is 100 volume%. In addition, it is desirable to process under reduced pressure, so that the density | concentration of ozone gas is high. High-concentration ozone gas may not exist unless it is under reduced pressure. Usually, a reduced pressure within a range of about 200 Pa to 10 Pa is suitable.

  The processing time (time for allowing ozone gas to act) is also the same as in the above-described embodiment. Basically, it may be sufficient time for the thin film on the substrate to be peeled and removed without residue, but the ozone gas concentration and the substrate heating temperature are slightly different depending on the ozone gas concentration and the substrate heating temperature. Etc. may be determined as appropriate.

  Further, the ozone gas treatment is performed while heating the mask blank or the transfer mask. In this embodiment as well, the heating temperature in this case further promotes the reaction for forming a low-melting-point metal oxide. For this purpose, a condition where the temperature of the substrate is 100 ° C. or higher is preferable. On the other hand, if the heating temperature in this case is too high, there is a possibility that the lower layer film under the substrate or the thin film may be adversely affected such as deterioration. Therefore, the upper limit of the heating temperature is preferably about 300 ° C.

  In the present invention, for example, a binary mask blank using a thin film made of a chromium-based material as a light shielding film or a binary mask produced using this mask blank removes the light shielding film (pattern) to regenerate the substrate, For example, a binary type having a structure in which a thin film made of a material containing a transition metal and silicon (Si) or a material containing tantalum (Ta) is used as a light shielding film, and an etching mask film made of a chromium-based material is provided on the light shielding film. When only the etching mask film (pattern) in the mask blank is removed to regenerate the substrate having the light shielding film, for example, from a material containing silicon (Si) or a material containing a transition metal and silicon (Si) As an example of a light-shielding film for forming a light-shielding band on the phase-shift film. When only the light shielding film (pattern) in the phase shift mask blank having a structure including a thin film of a chromium-based material is removed and the substrate including the phase shift film is reproduced, for example, a thin film made of a chromium-based material is used as the light shielding film. The present invention can be particularly preferably applied to the case where the substrate is regenerated by removing the light shielding film in the substrate dug type phase shift mask blank.

  As described above, according to the substrate recycling method of the present invention, the thin film is removed by applying ozone gas to the thin film while heating the mask blank or the transfer mask produced using the mask blank. By doing so, the thin film residue can be removed without remaining, and the damage of the substrate after the thin film removal or the lower layer film under the thin film can be reduced. Further, since the process load of the substrate re-polishing is reduced, the cost for regenerating the substrate can be reduced. In addition, since a high-quality substrate can be reproduced at low cost in this manner, it is particularly suitable for regenerating a mask blank using an expensive base material having high added value.

The present invention also provides a method for manufacturing a mask blank using a substrate regenerated by this regenerating method. A mask blank using a high-quality regenerated substrate is produced by forming a thin film for pattern formation again on the substrate regenerated by the regenerating method according to the present invention by using, for example, a DC magnetron sputtering method. Can do.
Furthermore, the present invention also provides a method for producing a transfer mask using this mask blank. That is, by patterning the thin film in the mask blank obtained by the mask blank manufacturing method using the reproduction substrate, a transfer mask having a thin film pattern formed on the substrate can be manufactured.

Hereinafter, the embodiment of the present invention will be described more specifically with reference to examples. In addition, a comparative example for the embodiment will be described.
Example 1
On a translucent substrate made of synthetic quartz glass, a mixed target of molybdenum (Mo) and silicon (Si) (atomic% ratio Mo: Si = 13: 87) is used as a sputtering target by using a single wafer sputtering apparatus. Used, in a mixed gas atmosphere of argon (Ar) and nitrogen (N ₂ ), by reactive sputtering (DC sputtering), a MoSiN film (film composition Mo: 9.9 atomic%, Si: 66.1 atomic%, N : 24.0 atomic%) with a film thickness of 50 nm, and subsequently using a Mo / Si target (atomic% ratio Mo: Si = 13: 87), argon (Ar) and nitrogen (N ₂ ) In a mixed gas atmosphere, a MoSiN film (film composition Mo: 7.5 atomic%, Si: 50.5 atomic%, N: 42.0 atomic%) is formed with a film thickness of 10 nm, whereby a MoSiN film and a MoSiN film are formed. ArF excimer laser having a layered to form a (Wavelength 193 nm) light-shielding film.

In addition, the optical density of the light shielding film with respect to ArF excimer laser was 3.0. Further, the surface reflectance of the light shielding film with respect to the wavelength of 193 nm of the exposure light was 18%. Furthermore, when the optical density of the light shielding film was measured at 25 locations within the surface and the in-plane variation (in-plane uniformity) of the optical density was measured, 3σ (σ is the standard deviation) was 0.02. The optical density was measured using a spectrophotometer (Shimadzu Corporation: ss3700).
Moreover, when the surface roughness of the surface of the said light shielding film was measured using the atomic force microscope (AFM) (measurement area 1 micrometer x 1 micrometer), it was Ra = 0.40nm.

Next, the following Cr etching mask film was formed on the MoSi light shielding film.
Specifically, a chromium (Cr) target is used as a sputtering target, and a mixed gas atmosphere of argon (Ar) and nitrogen (N ₂ ) (in a reactive sputtering (DC sputtering), a 5 nm thick CrN film ( Film composition Cr: 75.3 atomic%, N: 24.7 atomic%) The film composition of each layer is the result of analysis by RBS (Rutherford backscattering analysis).

As described above, using the binary mask blank in which the MoSi-based light-shielding film and the Cr-based etching mask film were formed on the glass substrate, a binary mask was manufactured according to the manufacturing process shown in FIG.
First, for example, a positive resist film for electron beam drawing was formed on the mask blank (see FIG. 1A), and a desired device pattern was drawn on the resist film. After the drawing, the resist film was developed to form a resist pattern (see FIG. 5B).

Next, using the resist pattern as a mask, the Cr-based etching mask film was etched by dry etching using a mixed gas of chlorine and oxygen to form an etching mask film pattern (see FIG. 5C). The remaining resist pattern was removed by ashing.
Next, using the etching mask film pattern as a mask, the MoSi light shielding film was etched by dry etching using a fluorine-based gas (mixed gas of SF ₆ and He) to form a light shielding film pattern (see FIG. d)).

Next, according to the above-described method of the present invention, a treatment for causing ozone gas to act on the etching mask film was performed.
That is, a substrate in which the etching mask film pattern and the light shielding film pattern are formed in a chamber is installed, and a high-concentration ozone gas (100% by volume) is introduced into the chamber to provide a Cr-based etching mask on the substrate. The film was brought into contact with the high-concentration ozone gas. At this time, the gas pressure was 100 Pa, the substrate was heated to 100 ° C., and the treatment time was 10 minutes.
The etching mask film pattern was peeled and removed by this ozone gas treatment.

In this way, a binary mask in which a MoSi light-shielding film pattern was formed on a translucent substrate was completed (see (e) in the figure).
When the surface of the MoSi light-shielding film pattern of the produced binary mask was observed in detail using an SEM (scanning electron microscope), no residue of the Cr-based etching mask film was confirmed.
Moreover, when the surface roughness of the said light shielding film pattern surface was measured using the atomic force microscope (AFM) (measurement area 1 micrometer x 1 micrometer), it was Ra = 0.45nm. That is, there was no deterioration in the surface roughness of the lower layer film (light-shielding film pattern) after the removal of the etching mask film.

Furthermore, the optical density of the light-shielding film pattern was 3.0, which was not changed before the etching mask film was removed. Moreover, although the surface reflectance of the light shielding film pattern with respect to the wavelength of 193 nm of the ArF excimer laser exposure light was also confirmed, almost no change was observed before the etching mask film removal.
Thus, before and after the removal of the etching mask film by the ozone gas treatment according to the present invention, the surface roughness, optical characteristics, etc. of the light shielding film, which is the lower layer film of the etching mask film, do not change (deteriorate), that is, the etching mask film. It was confirmed that the etching mask film could be removed without causing damage to the light-shielding film after the removal and without leaving a residue.

(Example 2)
In the manufacturing process of Example 1, after forming the next light-shielding film pattern without removing the remaining resist pattern at the stage of forming the upper etching mask film pattern, ozone gas is removed when the etching mask film pattern is removed. The resist pattern remaining on the etching mask film pattern was removed together by allowing ethylene gas to be mixed and acting. In this case, the flow rate ratio between ozone gas (100% by volume) and ethylene gas was set to 2: 1. As in Example 1, the treatment time (time for allowing ozone gas and ethylene gas to act) was 10 minutes, and the substrate was heated to 100 ° C.
Except for this point, a binary mask was fabricated in the same manner as in Example 1.

  Also in this embodiment, before and after the removal of the etching mask film by the ozone gas treatment according to the present invention, the surface roughness, optical characteristics, etc. of the light shielding film, which is the lower layer film of the etching mask film, do not change (deteriorate), that is, etching It was confirmed that the etching mask film could be removed without causing damage to the light-shielding film after removing the mask film and without leaving any residue.

(Example 3)
On a translucent substrate made of synthetic quartz glass, a mixed target of molybdenum (Mo) and silicon (Si) (atomic% ratio Mo: Si = 21: 79) is used as a sputtering target using a single wafer sputtering apparatus. Used, in a mixed gas atmosphere of argon (Ar) and nitrogen (N ₂ ) (gas pressure 0.07 Pa, gas flow ratio Ar: N ₂ = 25: 28), the power of the DC power source is 2.1 kW, and the reactivity A MoSiN film (light-shielding layer) is formed to a thickness of 50 nm by sputtering (DC sputtering), and subsequently, using a Mo / Si target (atomic% ratio Mo: Si = 4: 96), argon (Ar) and oxygen (O ₂ ), nitrogen (N ₂ ) and helium (He) in a mixed gas atmosphere (gas pressure 0.1 Pa, gas flow ratio Ar: O ₂ : N ₂ : He = 6: 3: 11: 17) DC power supply The power was 3.0 kW, and a MoSiON film (surface antireflection layer) was formed to a thickness of 10 nm, thereby forming a light-shielding film for ArF excimer laser (wavelength 193 nm) comprising a laminate of a MoSiN film and a MoSiON film.

In addition, the optical density of the light shielding film with respect to ArF excimer laser was 3.0. The surface reflectance of the light shielding film with respect to the wavelength of 193 nm of the exposure light was 20%. Furthermore, when the optical density of the light shielding film was measured at 25 locations within the surface and the in-plane variation (in-plane uniformity) of the optical density was measured, 3σ (σ is the standard deviation) was 0.02.
Further, when the surface roughness of the surface of the light shielding film was measured using an atomic force microscope (AFM) (measurement area 1 μm × 1 μm), Ra = 0.52 nm.
Next, a Cr-based etching mask film was formed on the MoSi-based light shielding film. Specifically, a chromium (Cr) target is used as a sputtering target, and a mixed gas atmosphere of argon (Ar), nitrogen (N ₂ ), carbon dioxide (CO ₂ ), and helium (He) is used, and reactive sputtering (DC A CrOCN film (film composition Cr = 33.6 atomic%, O = 38.9 atomic%, C = 11.2 atomic%, N = 16.3 atomic%) having a thickness of 10 nm was formed by sputtering.

As described above, a binary mask was produced in the same manner as in Example 1 using the binary mask blank in which the MoSi light shielding film and the Cr etching mask film were formed on the glass substrate.
The ozone gas treatment was performed under the same conditions as in Example 1 except that the substrate was set to 150 ° C., and the etching mask film pattern was peeled off.

When the surface of the MoSi light-shielding film pattern of the produced binary mask was observed in detail using an SEM (scanning electron microscope), no residue of the Cr-based etching mask film was confirmed.
Moreover, when the surface roughness of the said light shielding film pattern surface was measured using the atomic force microscope (AFM) (measurement area 1 micrometer x 1 micrometer), it was Ra = 0.54nm. That is, there was no deterioration in the surface roughness of the lower layer film (light-shielding film pattern) after the removal of the etching mask film.

Furthermore, the optical density of the light-shielding film pattern was 3.0, which was not changed before the etching mask film was removed. Moreover, although the surface reflectance of the light shielding film pattern with respect to the wavelength of 193 nm of the ArF excimer laser exposure light was also confirmed, almost no change was observed before the etching mask film removal.
Thus, also in this embodiment, the surface roughness and optical characteristics of the light shielding film, which is the lower layer of the etching mask film, change (deteriorate) before and after the removal of the etching mask film by the ozone gas treatment according to the present invention. In other words, it was confirmed that the etching mask film could be removed without causing damage to the light shielding film after the etching mask film was removed and without leaving a residue.

Example 4
Reactive in a mixed gas atmosphere of xenon (Xe) and nitrogen (N ₂ ) using a single wafer sputtering device on a translucent substrate made of synthetic quartz glass, using a tantalum (Ta) target as a sputtering target. A TaN film (film composition Ta = 85 atomic%, N = 15 atomic%) is formed by sputtering (DC sputtering) to a film thickness of 42 nm, and subsequently, using a Ta target, argon (Ar) and oxygen (O ₂ ). In a mixed gas atmosphere, a TaO film (film composition Ta = 39 atomic%, O = 59 atomic%) is formed with a film thickness of 9 nm, whereby an ArF excimer laser (wavelength: 193 nm) composed of a TaN film and a TaO film is formed. ) Light shielding film was formed. The film composition of each layer is an analysis result by AES (Auger electron spectroscopy).

In addition, the optical density of the light shielding film with respect to ArF excimer laser was 3.0. Further, the surface reflectance of the light shielding film with respect to the wavelength of 193 nm of the exposure light was 25%. Furthermore, when the optical density of the light shielding film was measured at 25 locations within the surface and the in-plane variation (in-plane uniformity) of the optical density was measured, 3σ (σ is the standard deviation) was 0.02.
Further, when the surface roughness of the surface of the light shielding film was measured using an atomic force microscope (AFM) (measurement area 1 μm × 1 μm), Ra = 0.29 nm.
Next, a Cr-based etching mask film similar to that in Example 3 was formed on the Ta-based light shielding film.

As described above, a binary mask was produced in the same manner as in Example 1 using a binary mask blank in which a Ta light shielding film and a Cr etching mask film were formed on a glass substrate.
Note that SF ₆ was used as the fluorine-based gas when the Ta-based light shielding film was dry-etched using the Cr-based etching mask film pattern as a mask to form the light-shielding film pattern. Also, the ozone gas treatment was performed under the same conditions as in Example 3, whereby the etching mask film pattern was peeled and removed.

When the surface of the produced Ta-type light-shielding film pattern of the binary mask was observed in detail using an SEM (scanning electron microscope), no residue of the Cr-based etching mask film was confirmed.
Further, when the surface roughness of the light shielding film pattern surface was measured using an atomic force microscope (AFM) (measurement area 1 μm × 1 μm), Ra = 0.32 nm. That is, there was no deterioration in the surface roughness of the lower layer film (light-shielding film pattern) after the removal of the etching mask film.

Furthermore, the optical density of the light-shielding film pattern was 3.0, which was not changed before the etching mask film was removed. Moreover, although the surface reflectance of the light shielding film pattern with respect to the wavelength of 193 nm of the ArF excimer laser exposure light was also confirmed, almost no change was observed before the etching mask film removal.
Thus, also in this embodiment, the surface roughness and optical characteristics of the light shielding film, which is the lower layer of the etching mask film, change (deteriorate) before and after the removal of the etching mask film by the ozone gas treatment according to the present invention. In other words, it was confirmed that the etching mask film could be removed without causing damage to the light shielding film after the etching mask film was removed and without leaving a residue.

(Example 5)
A synthetic quartz glass substrate having a size of 6 inches square and a thickness of 0.25 inches was used as the light transmitting substrate, and a light semi-transmitting film made of nitrided molybdenum and silicon was first formed on the light transmitting substrate.
Specifically, using a mixed target of molybdenum (Mo) and silicon (Si) (Mo: Si = 10 mol%: 90 mol%), mixing argon (Ar), nitrogen (N ₂ ), and helium (He). In a gas atmosphere (gas flow ratio Ar: N ₂ : He = 5: 49: 46), a gas pressure of 0.3 Pa, a DC power source power of 3.0 kW, and reactive sputtering (DC sputtering), molybdenum, silicon, and A MoSiN film made of nitrogen was formed to a thickness of 69 nm. Next, the substrate on which the MoSiN film was formed was subjected to heat treatment using a heating furnace in the atmosphere at a heating temperature of 450 ° C. and a heating time of 1 hour. This MoSiN film had an transmittance of 6.16% and a phase difference of 184.4 degrees in an ArF excimer laser. Further, when the surface roughness of the surface of the MoSiN light semitransmissive film was measured using an atomic force microscope (AFM) (measurement area 1 μm × 1 μm), Ra = 0.20 nm.

Next, a light shielding film having the following surface antireflection layer was formed on the light semitransmissive film.
Specifically, a chromium (Cr) target is used as a sputtering target, and a mixed gas atmosphere of argon (Ar), carbon dioxide (CO ₂ ), nitrogen (N ₂ ), and helium (He) (gas pressure 0.2 Pa, Gas flow ratio Ar: CO ₂ : N ₂ : He = 20: 35: 10: 30), the power of the DC power source is 1.7 kW, and a 30 nm thick CrOCN layer is formed by reactive sputtering (DC sputtering). Filmed. Subsequently, a mixed gas atmosphere of argon (Ar) and nitrogen (N ₂ ) (gas pressure 0.1 Pa, gas flow ratio Ar: N ₂ = 25: 5) was set, and the power of the DC power source was set to 1.7 kW. A 4 nm thick CrN layer was formed by reactive sputtering (DC sputtering). Finally, a mixed gas atmosphere of argon (Ar), carbon dioxide (CO ₂ ), nitrogen (N ₂ ), and helium (He) (gas pressure 0.2 Pa, gas flow ratio Ar: CO ₂ : N ₂ : He = 20: 35: 5: 30), the power of the DC power source is 1.7 kW, and a CrOCN layer having a film thickness of 14 nm is formed by reactive sputtering (DC sputtering). A chromium-based light shielding film was formed.
This light-shielding film has a laminated structure with the light semi-transmissive film and is adjusted so that the optical density (OD) is 3.0 at a wavelength of 193 nm of ArF excimer laser exposure light.

As described above, a phase shift mask blank in which a MoSi-based semi-transmissive film and a Cr-based laminated light-shielding film were formed on a glass substrate was produced.
Next, according to the method of the present invention, a treatment for causing ozone gas to act on the Cr-based light shielding film was performed.
That is, the phase shift mask blank is installed in a chamber, and a high-concentration ozone gas (100% by volume) is introduced into the chamber so that the Cr-based light shielding film of the mask blank is brought into contact with the high-concentration ozone gas. did. At this time, the gas pressure was 100 Pa, the substrate was heated to 100 ° C., and the processing time was 30 minutes.
By this ozone gas treatment, only the Cr-based light-shielding film was peeled and removed, and the mask blank substrate provided with the MoSi-based semi-transmissive film on the glass substrate was regenerated.

When the surface of the MoSi-based semi-transmissive film on the regenerated substrate was observed in detail using an SEM (scanning electron microscope), the residue of the Cr-based light-shielding film was not confirmed.
Further, when the surface roughness of the surface of the MoSi light semi-transmissive film was measured using an atomic force microscope (AFM) (measurement area 1 μm × 1 μm), Ra = 0.25 nm. That is, there was no deterioration of the surface roughness of the lower layer film (the light semi-transmissive film) after the removal of the Cr-based light shielding film.

Furthermore, the transmittance and phase difference of the MoSiN light semi-transmissive film with respect to the wavelength of 193 nm of ArF excimer laser exposure light were also confirmed, but almost no change was observed before the removal of the Cr-based light shielding film.
Thus, before and after the removal of the Cr-based light shielding film by the ozone gas treatment according to the present invention, the surface roughness, optical characteristics, etc. of the MoSi-based semi-transmissive film, which is the lower layer film of the Cr-based light shielding film, change (deteriorate). In other words, it was confirmed that only the Cr-based light-shielding film can be removed without causing damage to the MoSi-based light semi-transmissive film after the removal of the Cr-based light-shielding film and without leaving any residue. As a result, it was confirmed that it was possible to remove only the light shielding film from the phase shift mask blank having the light shielding film on the light semitransmissive film and to regenerate the substrate having the light semitransmissive film. .

(Comparative Example 1)
In the manufacturing process of Example 1, using the Cr-based etching mask film pattern as a mask, a MoSi-based light-shielding film composed of a laminated film of a MoSiN film and a MoSiN film is etched to form a light-shielding film pattern, and then the etching mask film pattern is Example 1 except that dry etching using a conventional mixed gas of chlorine and oxygen (flow rate ratio chlorine: oxygen = 4: 1) as an etching gas was performed in place of the treatment using ozone gas at the time of removal. In the same manner, a binary mask was produced.

  Moreover, when the surface roughness of the surface of the light shielding film pattern was measured using an atomic force microscope (AFM) (measurement area 1 μm × 1 μm), Ra = 0.72 nm, which is compared with that before the removal of the etching mask film. As a result, the surface roughness increased and the surface condition deteriorated.

Furthermore, the optical density of the light-shielding film pattern was 3.0, which was not changed before the etching mask film was removed. In addition, the surface reflectance of the light shielding film pattern with respect to the wavelength of 193 nm of ArF excimer laser exposure light was also confirmed to be 25%, which is greatly changed from before the etching mask film removal, which may affect the mask performance. is there.
Thus, when the etching mask film is removed by the conventional dry etching method, the damage to the lower layer film is large, and the surface roughness and optical characteristics of the light shielding film that is the lower layer film of the etching mask film are before and after the removal of the etching mask film. It has been confirmed that the above changes (deteriorates).

(Comparative Example 2)
In the manufacturing process of Example 3, using the Cr-based etching mask film pattern as a mask, forming a light-shielding film pattern by etching a MoSi-based light-shielding film composed of a laminated film of a MoSiN film and a MoSiON film, and then etching the etching mask film pattern. Example 1 except that dry etching using a conventional mixed gas of chlorine and oxygen (flow rate ratio chlorine: oxygen = 4: 1) as an etching gas was performed in place of the treatment using ozone gas at the time of removal. In the same manner, a binary mask was produced.

When the surface of the MoSi-based light-shielding film pattern of the fabricated binary mask was observed in detail using an SEM (scanning electron microscope), the residue of the Cr-based etching mask film was slightly confirmed.
Moreover, when the surface roughness of the surface of the light shielding film pattern was measured using an atomic force microscope (AFM) (measurement area 1 μm × 1 μm), Ra = 0.80 nm, which is compared with that before the removal of the etching mask film. As a result, the surface roughness increased and the surface condition deteriorated.

Furthermore, the optical density of the light-shielding film pattern was 3.0, which was not changed before the etching mask film was removed. Further, the surface reflectance of the light shielding film pattern with respect to the wavelength of 193 nm of the ArF excimer laser exposure light was confirmed to be 27%, which is greatly changed from before the etching mask film removal, which may affect the mask performance. is there.
Thus, when the etching mask film is removed by the conventional dry etching method, the damage to the lower layer film is large, and the surface roughness and optical characteristics of the light shielding film that is the lower layer film of the etching mask film are before and after the removal of the etching mask film. It has been confirmed that changes (degradation) etc.

DESCRIPTION OF SYMBOLS 1 Translucent substrate 2 Light shielding film 3 Etching mask film 4 Resist film 10 Mask blank 20 Transfer mask

Claims (20)

A method of removing a thin film from a substrate with a thin film in which a thin film made of a material containing a metal or a compound thereof is formed on the substrate,
A method for removing a thin film from a substrate with a thin film, wherein the thin film is removed by applying ozone gas to the thin film while heating the substrate with the thin film.   2. The method for removing a thin film from a substrate with a thin film according to claim 1, wherein the metal forms an oxide having a low melting point by applying ozone gas.   The method for removing a thin film from a substrate with a thin film according to claim 2, wherein the metal is chromium (Cr).   The method for removing a thin film from a substrate with a thin film according to any one of claims 1 to 3, wherein the concentration of ozone gas is 50 to 100% by volume.   The method for removing a thin film from a substrate with a thin film according to any one of claims 1 to 4, wherein a heating temperature of the substrate with a thin film is 100 ° C or higher. A method for manufacturing a transfer mask having a mask pattern for forming a transfer pattern on or on a substrate,
Producing a substrate with a pattern in which a mask pattern for forming a transfer pattern on a substrate or a substrate and a thin film pattern made of a material containing a metal or a compound thereof are sequentially formed;
A removal step of removing the thin film pattern,
In the removing step, the thin film pattern is removed by applying ozone gas to the thin film pattern while heating the patterned substrate.   7. The method of manufacturing a transfer mask according to claim 6, wherein the metal forms an oxide having a low melting point by applying ozone gas.   The method for manufacturing a transfer mask according to claim 7, wherein the metal is chromium (Cr).   The method for manufacturing a transfer mask according to any one of claims 6 to 8, wherein the concentration of ozone gas is 50 to 100% by volume.   The method for manufacturing a transfer mask according to claim 6, wherein the heating temperature of the substrate with a pattern is 100 ° C. or higher.   11. The method for manufacturing a transfer mask according to claim 6, wherein a resist pattern is formed on the thin film pattern, and the resist pattern and the thin film pattern are removed in the removing step. .   12. The transfer mask according to claim 11, wherein in the removing step, ozone gas and unsaturated hydrocarbon gas are allowed to act on the resist pattern and the thin film pattern to remove the resist pattern and the thin film pattern. Manufacturing method. A method of regenerating a substrate by removing the thin film of a mask blank provided with a thin film made of a material containing a metal for pattern formation or a compound thereof on the substrate or a transfer mask prepared using the mask blank,
A method for reclaiming a substrate, comprising removing the thin film by applying ozone gas to the thin film while heating the mask blank or the transfer mask. A method of regenerating a substrate by removing the thin film of a mask blank including a laminated film on a surface of which a thin film made of a material containing a metal or a compound thereof is formed on a substrate,
A method for regenerating a substrate, comprising removing ozone by applying ozone gas to the thin film while heating the mask blank.   15. The method for regenerating a substrate according to claim 13, wherein the metal forms an oxide having a low melting point by applying ozone gas.   The method for regenerating a substrate according to claim 15, wherein the metal is chromium (Cr).   The method for regenerating a substrate according to any one of claims 13 to 16, wherein the concentration of ozone gas is 50 to 100% by volume.   18. The method for regenerating a substrate according to claim 13, wherein a heating temperature of the mask blank or the transfer mask is 100 ° C. or more.   A method for manufacturing a mask blank, comprising forming a thin film for pattern formation on a substrate regenerated by the method for regenerating a substrate according to claim 13. A method for manufacturing a transfer mask, comprising: patterning the thin film in a mask blank obtained by the method for manufacturing a mask blank according to claim 19 to form a thin film pattern on the substrate.

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