JP5384106B2 - Resist film peeling method, mask blank manufacturing method, and transfer mask manufacturing method - Google Patents

Description

  The present invention relates to a resist film peeling method, a mask blank manufacturing method, and a transfer mask manufacturing method for peeling a resist film from a mask blank having a resist film formed on a transfer pattern thin film.

  When manufacturing semiconductor devices, liquid crystal devices, etc., in the process of patterning a base film made of metal or a metal compound using photolithography technology, after applying a resist to the surface of the base film, the resist is exposed using a transfer mask. Next, the resist is developed using a developing solution to form a resist pattern, and the underlying film is etched using the resist pattern as a mask. After that, the resist pattern is removed using a stripping solution.

  Further, when a transfer mask is produced, a transfer pattern made of a metal (for example, chromium) or a metal compound (for example, a chromium compound containing at least one of oxygen, nitrogen, and carbon in chromium) is also formed on the substrate. After forming a thin film for use (for example, a light-shielding film), a mask blank is produced by applying a resist on the transfer pattern thin film. Next, after exposing the resist using a technique such as electron beam drawing or laser drawing, the resist is developed using a developer to form a resist pattern, and the transfer pattern thin film is etched using this resist pattern as a mask. To do. After that, the resist pattern is removed using a stripping solution.

  In such mask blanks, since the sensitivity of the resist film changes after a certain period of time, the mask blanks are always stocked to some extent at the manufacturing site (for example, mask blank manufacturing site and transfer mask manufacturing site). Then, mask blanks that cannot be used due to a change in sensitivity of the resist film are generated. Further, when a mask blank is formed by applying a resist on a transfer pattern thin film, a convex or concave defect may occur on the resist film surface for some reason. In such a case, if the resist film is peeled off from the mask blank and the substrate and the transfer pattern thin film formed on the substrate can be reused, the manufacturing cost can be reduced.

  In particular, as a resist film used for mask blanks, a chemically amplified resist film has been used in recent years. This chemically amplified resist film has high sensitivity, but the period until the sensitivity change starts is shorter than the conventional polymer resist film, so the sensitivity change of the resist film progresses in a relatively short period of time, and the mask Blanks can become unusable. Therefore, if the resist film is peeled from such a mask blank and the substrate and the transfer pattern thin film formed on the substrate can be reused, the manufacturing cost can be greatly reduced.

  By the way, in order to miniaturize the pattern of a semiconductor device, in addition to miniaturization of a mask pattern formed on a photomask, it is necessary to shorten the wavelength of an exposure light source used in photolithography. As an exposure light source for manufacturing a semiconductor device, in recent years, KrF excimer laser (wavelength 248 nm), ArF excimer laser (wavelength 193 nm), F2 excimer laser (wavelength 157 nm), EUV (extreme ultraviolet light: wavelength 13 to 14 nm) are used. The wavelength has been shortened.

  In addition, in order to perform fine pattern transfer using a photomask, it is necessary to suppress the damage of the transfer pattern thin film due to the resist film peeling with almost no change to the reflectance of the transfer pattern thin film before forming the resist film. . This is because it is necessary to prevent pattern defects when a transfer mask is produced from a mask blank and a semiconductor device or a liquid crystal device having a fine pattern is produced by lithography using the transfer mask. Because.

  Further, in order to inspect whether a fine pattern is formed on the photomask during the photomask manufacturing process, the surface of the layer patterned using the resist film as a mask and the patterned resist as a mask The inspection is performed by the difference in the surface reflectance with the exposed layer. For this reason, if damage is caused by peeling off the resist film, the transfer pattern thin film and a so-called hard mask, which will be described later, cause fluctuations in the surface reflectance, so whether or not a fine pattern formation as designed has been made. The inspection cannot be performed with high accuracy.

  Therefore, it is necessary to minimize damage to the transfer pattern thin film and the hard mask due to the resist film peeling.

Here, as a technique for removing and removing the resist film (resist film subjected to exposure and development), ashing treatment using plasma, etc., sulfuric acid (H ₂ SO ₄ ) and hydrogen peroxide water (H ₂ O ₂ ) Chemical treatment using a mixed liquid (SPM), chemical treatment using a mixed liquid (APM) of ammonia (NH ₃ ) and hydrogen peroxide water, treatment with ozone water, and the like have been proposed (Patent Documents 1 and 2). reference).
JP 2003-273079 A Japanese Patent No. 3344391

  However, when the resist film is peeled off from the mask blank having the transfer pattern thin film and the resist film formed on the substrate, a mixed liquid of sulfuric acid and hydrogen peroxide solution or the like is used as in the conventional resist film peeling method. When treated with an acidic or alkaline aqueous solution such as a mixed liquid of ammonia and hydrogen peroxide, a trace amount of chemical components remain on the substrate, and if this remains until the mask, the chemical reaction is promoted by laser irradiation. As a result, there arises a problem that the transfer pattern thin film becomes defective as a foreign matter. In addition, the above aqueous solution has a problem of high danger to the human body.

  Furthermore, in Patent Document 2, it is proposed to use ozone water in removing the resist film after patterning. However, in the technique disclosed herein, the resist film after being used for patterning is targeted for removal. This is not a technique for removing the resist film before development. For this reason, Patent Document 2 proposes supplying high-concentration ozone water and an ozone decomposition catalyst solution onto the substrate, assuming that the resist film cannot be efficiently removed with low-concentration ozone water. However, in such a method, since the reactivity is high, it is considered impossible to remove only the resist film while leaving the base film formed under the resist film in a reusable state.

  In particular, with regard to the above problems, when the resist film is peeled off from the mask blank in which the transfer pattern thin film and the resist film to be the transfer pattern are formed on the substrate, the surface of the underlying transfer pattern thin film is damaged (damaged). When the optical characteristics (reflectance and transmittance) are changed, a transfer mask is manufactured using the mask blank, and pattern defects are produced when a semiconductor device or a liquid crystal device is manufactured using the transfer mask. This is a more serious problem.

  In view of the above problems, an object of the present invention is to remove only a resist film in a mask blank in which a transfer pattern thin film to be a transfer pattern and a resist film are formed on a substrate, and the transfer pattern thin film and the substrate. A resist film peeling method, a mask blank manufacturing method, and a transfer mask manufacturing method.

  In order to solve the above problems, the present invention adopts the following configuration.

In the present invention, the resist film is peeled from a mask blank having a substrate, a transfer pattern thin film to be a transfer pattern formed on the substrate, and a resist film formed on the transfer pattern thin film. A resist film peeling method, wherein an acid or alkaline aqueous solution is brought into contact with the resist film to reduce the thickness of the resist film, and the ozone water in which ozone is dissolved is thinned. Ozone water treatment is performed in which the resist film is dissolved in contact with the film.

  According to the said structure, the resist film before image development formed in the mask blank can be peeled, and the damage to the thin film for transfer patterns can be made very small. Therefore, with the resist film formed on the transfer pattern thin film, it was judged that the mask blank was defective or unusable due to changes in resist film sensitivity, resist film surface defects, resist film coating abnormalities, etc. With respect to the product, after removing only the resist film, a new resist film is formed again on the transfer pattern thin film, and can be used as a patterning of the transfer pattern thin film. Therefore, since both the substrate and the transfer pattern thin film can be reused, the manufacturing cost of the mask blanks can be reduced.

Further, according to the above configuration, after the resist film is thinned with an acidic or alkaline aqueous solution and then subjected to ozone water treatment, there is no resist film remaining after the resist film is peeled off, so that the resist film can be securely formed. Can be peeled off. In particular, in the case of a mask blank having a quadrangular shape, there may be a thick region in the resist film, such as the outer periphery of the substrate. The film can be peeled off.

In this case, the surface of the resist film formed on the base film or the transfer pattern thin film is surface-treated so that an acidic or alkaline aqueous solution is preferentially brought into contact with the resist film on the outer peripheral portion of the substrate. It is preferable to perform ozone water treatment as a whole.

In the present invention, the transfer pattern thin film is made of, for example, a material containing chromium.

As described above , the resist film peeling method of the present invention is particularly suitable when the transfer pattern thin film formed under the resist film is made of a material containing chromium.

In the present invention, the transfer pattern thin film may employ a configuration in which an antireflection layer having an antireflection function containing oxygen and / or nitrogen is provided as an upper layer.

According to the above configuration , the resist film is peeled off when an antireflection layer such as chromium oxide, chromium nitride, or chromium oxynitride containing oxygen and / or nitrogen is provided on the upper layer of the transfer pattern thin film. With respect to the previous reflectance, the variation in reflectance after the resist film is peeled can be suppressed to a level that does not substantially vary. Therefore, it is possible to provide an extremely reliable mask blank that guarantees the optical characteristics of the transfer pattern thin film.

In the present invention, the oxygen and / or nitrogen content in the antireflection layer is preferably 40 atomic% or more .

According to the above configuration, the optical characteristics (reflectance and transmittance) of the antireflection layer are not substantially changed, which is particularly good. From the viewpoint of not changing the optical characteristics more, the content of oxygen and / or nitrogen in the antireflection layer is preferably 50 atom% or more, more preferably 60% atom or more.

  In the present invention, after the resist film is peeled off by the ozone water treatment, it is preferable to perform a gas dissolved water treatment with a gas dissolved water.

  According to the above configuration, after the resist film is removed by the ozone water treatment, the residue is left on the surface of the base film or the transfer pattern thin film after the resist film is removed by performing the gas-dissolved water treatment with the gas-dissolved water. This is preferable because foreign substances can be removed reliably.

  In the present invention, the ozone water treatment is preferably performed using ozone water in which ozone is dissolved in an amount of 25 to 110 ppm.

  According to the said structure, since the resist film peeling efficiency becomes favorable, suppressing the damage with respect to the thin film for transcription | transfer patterns, it is preferable. The treatment temperature and treatment time in the ozone water treatment are appropriately set within a range that suppresses damage to the transfer pattern thin film. A preferable temperature range of the processing temperature is 20 ° C to 35 ° C. The treatment time is preferably 1 to 20 minutes.

  In the mask blank manufacturing method using the resist film peeling method according to the present invention, after the resist film formed on the transfer pattern thin film is peeled off, a new resist film is formed on the transfer pattern thin film. It is characterized by that.

  According to the above configuration, by using the resist film peeling method to which the present invention is applied, the substrate can be effectively used in the state of the substrate with the transfer pattern thin film, and thus the manufacturing cost of mask blanks can be reduced. .

  In the present invention, the mask blank is, for example, a mask blank for KrF excimer laser exposure, a mask blank for ArF excimer laser exposure, a mask blank for F2 excimer laser exposure, or a mask blank for EUV exposure.

  In the transfer mask manufacturing method using the mask blank according to the present invention, the new resist film is selectively exposed and developed to form a resist pattern, and then the resist pattern is used as a mask for the transfer pattern. It is characterized by forming a transfer pattern by patterning a thin film.

  In the mask blanks to which the present invention is applied, after the new resist film is selectively exposed and developed to form a resist pattern, the transfer pattern is formed by patterning the transfer pattern thin film using the resist pattern as a mask. Thus, a transfer mask can be manufactured.

It is process sectional drawing which shows typically a mode that a mask blank is produced, and a mode that a transfer mask is produced using this mask blank. It is explanatory drawing which shows a mode that the resist film is thick in the edge part of mask blanks. In the resist film peeling method to which the present invention is applied, the surface temperature of the light-shielding film is optically measured when the ozone water treatment temperature is room temperature and the ozone water concentration and treatment time are changed. In the resist film peeling method to which the present invention is applied, the surface temperature of the light shielding film is optically measured when the ozone water treatment temperature is 25 ° C. and the ozone water concentration and treatment time are changed. . In the resist film peeling method to which the present invention is applied, the surface temperature of the light-shielding film is optically measured when the ozone water treatment temperature is 30 ° C. and the ozone water concentration and treatment time are changed. . In the resist film peeling method to which the present invention is applied, the surface temperature of the light-shielding film is optically measured when the treatment temperature of the ozone water treatment is 35 ° C. and the ozone water concentration and treatment time are changed. .

Explanation of symbols

1 Mask Blanks 10 Transfer Mask 11 Substrate 12 Light-shielding Film (Transfer Pattern Thin Film)
14 Resist film

  A resist film peeling method, a mask blank manufacturing method, and a transfer mask manufacturing method to which the present invention is applied will be described with reference to the drawings.

(Mask blanks and transfer mask manufacturing method)
FIG. 1 is a process cross-sectional view schematically showing how a mask blank is manufactured and how a transfer mask is manufactured using the mask blank.

To produce a transfer mask, first, as shown in FIG. 1A, synthetic quartz glass (for ArF excimer laser exposure), fluorine-doped quartz glass or calcium fluoride (for F2 excimer laser exposure), SiO ₂ − A substrate surface of a material made of a low expansion glass (for EUV exposure) such as TiO ₂ is mirror-polished and then cleaned to prepare a substrate 11 having a predetermined size (for example, 152.4 mm × 152.4 mm × 6.35 mm). To do.

  Next, as shown in FIG. 1B, a light-shielding film 12 that is a transfer pattern thin film is formed on the main surface of the substrate 11 by sputtering or vacuum deposition. The thickness of the light shielding film 12 is, for example, 40 nm to 120 nm, and is appropriately adjusted so that desired optical characteristics (for example, transmittance (optical density), reflectance, etc.) are obtained with respect to the wavelength of the exposure light. . As a material of the light shielding film 12, chromium or a chromium compound containing at least one of oxygen, nitrogen, and carbon can be used for chromium, and is appropriately selected according to optical characteristics with respect to the wavelength of exposure light, pattern cross-sectional characteristics, and the like. Selected. An antireflection layer having an antireflection function may be formed on the upper layer portion of the light shielding film 12. Such an antireflection layer is formed of, for example, a material containing oxygen and / or nitrogen in chromium. The oxygen and nitrogen contents in the antireflection layer are appropriately set according to the reflectance with respect to the wavelength of exposure light and the pattern cross-sectional characteristics.

  Further, another film may be formed between the substrate 11 and the light shielding film 12. Examples of the other film include a phase shift film (including a halftone film) having a desired phase difference with respect to exposure light, an etching stopper layer, and a conductive film. Further, another film may be formed on the light shielding film 12. For example, a hard mask made of an inorganic material having resistance against an etchant of the light shielding film that functions as a mask layer when patterning the light shielding film, for example, a material containing silicon can be used.

  Further, the transfer pattern thin film is not limited to the light shielding film. For example, when a resist film is peeled from a reflective mask blank in which a multilayer reflective film is formed on the substrate 11 as a mask blank and an absorber film and a resist film, which are transfer pattern thin films, are further formed on the multilayer reflective film. It can also be applied. In this case, examples of the material for the absorber film include a material containing chromium and a material containing tantalum.

  Next, as shown in FIG. 1C, a resist solution is applied onto the light shielding film 12 by spin coating or the like, and then heated and cooled to form, for example, a resist film 14 having a thickness of 50 nm to 500 nm. To do. As a result, the mask blank 1 in which the light shielding film 12 and the resist film 14 are laminated on the substrate 11 in this order is obtained.

  When a transfer mask is manufactured using the mask blank 1 configured as described above, first, electron beam drawing (selective exposure) is performed on the resist film 14 by an electron beam drawing apparatus, and then amines or the like. Development processing is carried out using a developer containing As a result, a resist pattern 140 shown in FIG. 1D is formed.

  Next, dry etching is performed on the light shielding film 12 using an etching gas containing a chlorine-based gas using the resist pattern 140 shown in FIG.

Next, the resist pattern 140 is stripped with a resist stripping solution made of a mixed solution of hydrogen peroxide (H ₂ O ₂ ) and sulfuric acid (H ₂ SO ₄ ), etc. The transfer mask 10 having the transfer pattern 120 shown in FIG.

(Removal method 1 of resist film 14)
In the method of peeling the resist film 14 in the mask blank described above , as shown in FIG. 1C, when the mask blank 1 is manufactured, a defect is found in the resist film 14 or the mask blank 1 is long. For example, when the sensitivity of the resist film 14 is greatly changed because it has been stored for a period of time, a method of immersing the mask blanks 1 in ozone water in which ozone is dissolved, or ozone water on the surface on which the resist film is formed. The resist film 14 is peeled by bringing the resist film 14 into contact with ozone water by a method such as supplying (ozone water treatment).

  Then, after removing only the resist film 14, a new resist film 14 is formed again on the light shielding film 12, and the mask blanks 1 are manufactured.

  Here, the ozone water is purified by an aeration method, a molten film processing method, or the like, but in order to effectively remove the resist film 14, it is necessary to use ozone water purified by the molten film processing method or the like. preferable. The ozone concentration of ozone water purified by the aeration method has a limit of about 20 ppm, and such a low concentration of ozone water has a very slow dissolution rate for dissolving the resist film 14. On the other hand, the ozone concentration of ozone water purified by the melt film processing method or the like is a high concentration of about 25 ppm to 110 ppm, and the dissolution rate for dissolving the resist film 14 is moderately fast, so that the resist film is surely removed from the light shielding film 12. 14 can be peeled off.

  According to the above resist film peeling method, the resist film 14 before development can be efficiently peeled off with ozone water, and damage to the surface of the light shielding film 12 is extremely small.

  Further, an antireflection layer having an antireflection function containing oxygen and / or nitrogen is provided on the upper layer of the transfer pattern thin film, and the content of oxygen and / or nitrogen in the antireflection layer is 40 atomic% or more. This is particularly preferable because the optical characteristics (reflectance and transmittance) of the light shielding film 12 are not substantially changed. Furthermore, it is preferably 50 atomic% or more, more preferably 60 atomic% or more from the viewpoint of further changing the optical properties.

  Therefore, the optical characteristics (reflectance and transmittance) of the light shielding film 12 are not substantially changed. After that, after removing only the resist film 14, a new resist film 14 is formed on the light shielding film 12 again. Even when the mask blanks 1 are manufactured by forming the mask blanks 1, the optical characteristics of the light shielding film 12 are guaranteed, and the mask blanks 1 with high reliability can be manufactured. Further, since both the substrate 11 and the light shielding film 12 can be reused, the manufacturing cost of the mask blanks 1 can be reduced.

(Removal method 2 of resist film 14)
As shown in FIG. 2, the resist film peeling method to which the present embodiment is applied is compared with the central region where the transfer pattern is formed in the outer periphery of the mask blank 1 manufactured as shown in FIG. Thus, this method is suitable for the case where the resist film 14 is formed to be thick, and the following processing is performed. First processing: processing with an acidic or alkaline aqueous solution (thickness reduction processing)
Second treatment: Ozone water treatment Third treatment: Gas dissolved water treatment (foreign matter residue removal treatment)
I do. That is, before the ozone water treatment, a chemical solution composed of a mixed liquid (SPM) of sulfuric acid (H ₂ SO ₄ ) and hydrogen peroxide water (H ₂ O ₂ ), ammonia (NH ₃ ) and hydrogen peroxide water The film thickness of the resist film 14 is reduced by a chemical solution composed of a mixed liquid (APM), a developer containing an amine, or the like. In addition, after the ozone water treatment, a gas-dissolved water treatment for removing foreign matters remaining on the surface of the light-shielding film 12 after removing the resist film 14 with a gas-dissolved water such as hydrogen water (hydrogen gas-dissolved water). Do. In the first treatment, it is preferable that an acidic or alkaline aqueous solution is preferentially brought into contact with a region where the thickness of the resist film 14 on the outer peripheral portion of the substrate is thick.

  Here, in the treatment with the above acidic or alkaline aqueous solution or the gas-dissolved water treatment, the entire substrate may be immersed in these aqueous solution or gas-dissolved water. May be supplied.

  Then, after removing only the resist film 14, a new resist film 14 is formed again on the light shielding film 12, and the mask blanks 1 are manufactured.

  As described above, in the present embodiment, when there is a thick region in the resist film 14 on the outer peripheral portion of the substrate 11, the resist film on the outer peripheral portion of the substrate 11 is processed by treatment with oxygen or an alkaline aqueous solution. In order to reduce the film thickness of the resist film 14 on the entire surface of the light shielding film 12 while preferentially reducing the film thickness 14, the ozone water treatment is performed, so that the resist film 14 is reliably removed in a short time. Can do. In addition, in this case, since the acid or alkaline treatment is performed at a relatively first stage in the resist film peeling method, the surface of the light-shielding film 12 is not damaged (damaged), and the light-shielding film is caused by the remaining aqueous solution. 12 is not damaged. Further, in the gas-dissolved water treatment performed after the ozone water treatment, no acid or alkali remains on the surface of the light shielding film 12 and the light shielding film 12 is not damaged.

  Further, in the ozone water treatment performed after the treatment with an acidic or alkaline aqueous solution, the resist film 14 can be removed and peeled at a sufficient dissolution rate if the resist film 14 is not developed, and the light-shielding film 12 is extremely damaged. small. Therefore, in the case where the use is not necessary with the resist film 14 formed on the light shielding film 12, after removing only the resist film 14, a new resist film 14 is formed on the light shielding film 12 again. It can be used for patterning of a light shielding film. Therefore, since it can be reused in both the substrate and the light shielding film, the manufacturing cost of the mask blanks 1 can be reduced.

  Further, in the resist film 14 peeling method performed only by treatment with an acidic or alkaline aqueous solution, treatment traces are generated, and thus further treatment with chemical rinsing or the like is necessary. In this embodiment, a plurality of treatments are performed. Since they are used in combination, it is possible to suppress the occurrence of a processing trace due to the resist film peeling on the surface of the light shielding film 12. Moreover, the usage amount of a chemical liquid with high risk can be reduced, and a load such as waste liquid treatment can be reduced.

(Other embodiments)
In the above embodiment, the material of the resist film 14 is arbitrary, but in the case of a chemically amplified resist film, there is an advantage that the sensitivity is high, but the sensitivity tends to easily change. Therefore, when a chemically amplified resist film is used as the resist film 14, the light-shielding film 12 and the substrate 11 are reused even when the sensitivity change is significant and cannot be actually used for manufacturing a transfer mask. Thereby, the manufacturing cost of mask blanks can be reduced significantly.

(Example 1)
Hereinafter, the present invention will be described in more detail based on examples. In this embodiment, the resist film peeling method 2 described above is employed. That is, as shown in FIG. 1C, after the mask blank 1 is manufactured, when a defect is found in the resist film 14, or because the mask blank 1 is stored for a long time, the sensitivity change of the resist film 14 changes. Is increased, the following processing is performed: first processing: developer processing containing amines second processing: ozone water processing third processing: hydrogen water processing. Here, the ozone water treatment in the second treatment is performed under the following conditions: Ozone water concentration: 30, 70, 90, 110 ppm
Treatment temperature: room temperature, 25, 30, 35 ° C
Processing time: 1, 2, 3, 5, 7, 10 minutes, and the reflectance of the light shielding film 12 after peeling the resist film 14 formed under these conditions is measured to evaluate the light shielding film damage did. The reflectance of the light shielding film 12 was measured with a spectrophotometer.

  An antireflection layer having an antireflection function is formed on the upper layer portion of the light shielding film 12, and the light shielding film 12 is formed from the substrate 11 side by a chromium nitride film (CrN film), a chromium carbide film (CrC film), an acid A chromium nitride film (CrON film) was used. The reflectance of the light shielding film 12 was 18% at an exposure wavelength of 193 nm. The resist film 14 was a chemically amplified resist film having a thickness of 350 nm.

  3 to 6 are graphs when optically measuring the state of the light shielding film 12 after removing the resist film 14 by changing the treatment temperature of the ozone water treatment to room temperature, 25 ° C., 30 ° C., and 35 ° C. It is. Here, the horizontal axis represents the wavelength of light used to measure the state of the light shielding film 12. The vertical axis represents the difference between the reflected light intensity from the light shielding film 12 after the resist film 14 is removed and the reflected light intensity from the light shielding film 12 after film formation (the light shielding film on which the resist 14 is not formed and peeled off). The smaller the absolute value, the smaller the damage received by the light shielding film 12 when the resist film 14 is peeled off. The numbers given to the lines in each graph indicate the results when the processing times are 1, 2, 3, 5, 7, and 10 minutes, respectively.

  As shown in FIGS. 3 to 6, within the range of the second processing condition, damage to the light-shielding film 12 due to the resist film peeling can be suppressed with almost no change with respect to the reflectance of the light-shielding film before forming the resist film. did it. This is a level at which pattern defects do not occur when a transfer mask is produced from a mask blank and a semiconductor device or a liquid crystal device is produced by lithography using the transfer mask. There appears to be no damage to the film.

  Further, when the defects on the surface of the light-shielding film 12 after the resist film was peeled were measured with a defect inspection apparatus, the resist film residue was not very good. After the resist film was peeled off, a new resist film 14 was formed on the light shielding film 12 to obtain a mask blank.

(Example 2)
On a translucent substrate made of synthetic quartz glass whose main surface and end face are precisely polished, an in-line sputtering system is used, a chromium target is used as a sputtering target, and reaction is performed in a mixed gas atmosphere of argon, nitrogen, and oxygen. By performing reactive sputtering, a light shielding film was formed, and a chemically amplified resist was applied to produce a photomask blank.

When a defect is found in the resist film after the mask blank 1 is manufactured in this way, or when the sensitivity change of the resist film 14 becomes large because it has been stored for a long time in the state of the mask blank 1, the following is performed. Process 1st process: Developer processing containing amines 2nd process: Ozone water process 3rd process: Hydrogen water process was performed. In addition, according to Rutherford backscattering analysis (RBS), an antireflection layer having an antireflection function in which the total amount of oxygen 40 atom% and nitrogen 20 atom% is 60 atom% is formed on the upper part of the light shielding film. The light shielding film was a chromium nitride film (CrN film), a chromium carbide film (CrC film), or a chromium oxynitride film (CrON film) from the substrate side.

  When the treatment temperature of the ozone water treatment was changed to room temperature, 25 ° C., 30 ° C., and 35 ° C. and the state of the light shielding film 12 after removing the resist film 14 was optically measured, Damage was suppressed with little change with respect to the reflectance of the light shielding film before the resist film was formed. This is a level at which pattern defects do not occur when a transfer mask is produced from a mask blank and a semiconductor device or a liquid crystal device having a fine pattern is produced by lithography using the transfer mask. It is considered that there is no damage to the light shielding film due to the resist film peeling.

  Further, when the defects on the surface of the light-shielding film 12 after the resist film was peeled were measured with a defect inspection apparatus, the resist film residue was not very good. After the resist film was peeled off, a new resist film 14 was formed on the light shielding film 12 to obtain a mask blank.

(Modification of Example 2)
In the above Example 2, the mask blanks were formed in the same manner as in Example 2 except that an antireflection layer having an antireflection function in which the total amount of oxygen and nitrogen was 30 atomic% was formed on the upper part of the light shielding film. The resist film 14 formed in 1 was peeled off. As a result, the variation in the reflectance of the light shielding film 12 due to the resist film peeling was more varied than that in Example 2, but was within 5%.

Example 3
On a translucent substrate made of synthetic quartz glass whose main surface and end face are precisely polished, an in-line sputtering system is used, a chromium target is used as a sputtering target, and reaction is performed in a mixed gas atmosphere of argon, nitrogen, and oxygen. Sputtering was performed.

Next, on the light-shielding chromium film 12, using a mixed target of molybdenum (Mo) and silicon (Si) (Mo: Si = 20: 80 [mol%]), argon (Ar) and nitrogen (N ₂ ). In the mixed gas atmosphere (Ar: N ₂ = 10: 90 [volume%], pressure 0.3 [Pa]), a hard mask film made of MoSiN was formed by performing reactive sputtering.

  Next, a chemically amplified resist was applied on the inorganic etching mask film 3 to produce a photomask blank.

After the mask blanks are manufactured in this way, when a defect is found in the resist film, or when the sensitivity change of the resist film 14 becomes large because it has been stored for a long time in the state of the mask blank 1, the following processing is performed. First treatment: Treatment with developer containing amines Second treatment: Ozone water treatment Third treatment: Hydrogen water treatment. In addition, according to Rutherford backscattering analysis (RBS), a layer having a total nitrogen amount of 60 atomic% was formed on the upper portion of the hard mask.

  The surface condition of the hard mask after removing the resist film 14 by changing the treatment temperature of the ozone water treatment to room temperature, 25 ° C., 30 ° C., and 35 ° C. was optically measured. The reflectivity was suppressed almost unchanged with respect to the surface reflectivity of the hard mask before forming the resist film. Thereby, when a transfer mask was produced from the mask blanks, it was possible to prevent deterioration of inspection accuracy as to whether or not a fine pattern was formed in a designed pattern.

  When a polymer resist was used instead of the chemically amplified resist in Examples 1 to 3, the same results as in Examples 1 to 3 could be obtained.

(Comparative Example 1)
In Example 1 described above, the resist film 14 formed on the mask blank 1 was peeled in the same manner as Example 1 except that the second process and the third process were not performed. As a result, the variation in reflectance of the light shielding film 12 due to the resist film peeling exceeded 5%. When the surface state of the light shielding film 12 after the resist film was peeled was observed, the surface was roughened by the first treatment. This state of the light shielding film 12 does not guarantee the optical characteristics of the light shielding film 12 in the mask blank 1. Therefore, it cannot be reused as a substrate with the light shielding film 12, and it is necessary to peel the light shielding film 12 and re-polish the substrate, so that the manufacturing cost of mask blanks cannot be reduced. Moreover, the result of deteriorating the accuracy of defect inspection performed in a subsequent process due to the change in the reflectance of the light shielding film 12 after the resist film was peeled off.

  In the present invention, since the resist film before development formed on the mask blank is peeled off with ozone water, the resist film can be peeled off without damaging the surface of the transfer pattern thin film. Therefore, with the resist film formed on the transfer pattern thin film, the mask blanks are defective or unusable due to changes in resist film sensitivity, resist film surface defects, resist film coating abnormalities, etc. With regard to the product, after removing only the resist film, a new resist film can be formed again on the transfer pattern thin film and used for patterning the transfer pattern thin film. Therefore, since both the substrate and the transfer pattern thin film can be reused, the manufacturing cost of the mask blanks can be reduced.

Claims (9)

A resist film peeling method for peeling a resist film from a mask blank having a substrate, a transfer pattern thin film to be a transfer pattern formed on the substrate, and a resist film formed on the transfer pattern thin film. There,
A process of bringing an acidic or alkaline aqueous solution into contact with the resist film to reduce the thickness of the resist film;
A resist film peeling method comprising performing ozone water treatment in which ozone water obtained by dissolving ozone is brought into contact with the thinned resist film to dissolve the resist film.   The resist film peeling method according to claim 1, wherein the transfer pattern thin film is made of a material containing chromium.   The resist film peeling method according to claim 1, wherein the transfer pattern thin film is provided with an antireflection layer having an antireflection function containing oxygen and / or nitrogen as an upper layer.   The resist film peeling method according to claim 3, wherein the content of oxygen and / or nitrogen in the antireflection layer is 40 atomic% or more. 2. The resist film peeling method according to claim 1, wherein after the resist film is peeled off by the ozone water treatment, gas dissolved water treatment with gas dissolved water is further performed . The resist film peeling method according to claim 1, wherein the ozone water treatment uses ozone water in which ozone is dissolved in an amount of 25 to 110 ppm . A mask blank manufacturing method using the resist film peeling method according to any one of claims 1 to 6,
A method for manufacturing a mask blank , comprising: peeling off the resist film formed on the transfer pattern thin film, and then forming a new resist film on the transfer pattern thin film . The mask blank is, KrF excimer laser exposure mask blank, ArF excimer laser exposure mask blank, F2 excimer laser exposure mask blank or mask blank according to claim 7, characterized in that the EUV exposure mask blank, Manufacturing method. A method for manufacturing a transfer mask using mask blanks manufactured by the manufacturing method according to claim 7,
Transcription and forming said selective exposure of a new resist film, after developed to form a resist pattern, and then the resist pattern as a mask by patterning said thin film for transfer pattern transferred pattern Mask manufacturing method.

Images