JP2011127221A - Method for regenerating substrate, method for producing mask blank, method for producing multilayer reflection film-fitted substrate and method for producing reflection type mask blank - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for regenerating a substrate in which the damage of a substrate after the removal of a thin film is reduced, and the process load of repolishing is reduced as well, thus the regeneration cost of the substrate can be reduced. <P>SOLUTION: The method for regenerating a substrate includes removing a mask blank provided with a thin film for forming a pattern on the main surface of a substrate made of a glass or removing the thin film of the mask for transfer produced using the mask blank. A substrate is regenerated by bringing the mask blank or the thin film of the mask for transfer into contact with a substance in a non-excited state comprising a compound of any element selected from chlorine (Cl), bromine (Br), iodine (I) and xenon (Xe), and fluorine (F) and removing it to regnerate the substrate. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a substrate recycling method for removing a thin film such as a mask blank to reproduce a substrate, a mask blank manufacturing method, a multilayer reflective film-coated substrate manufacturing method, and a reflective mask blank manufacturing method.

  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 or the like on a translucent glass substrate, and a photolithography 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 imparts 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 as a light-shielding film have been used.

  By the way, the price competition for electronic parts such as semiconductor devices in recent years is becoming more and more severe, and it is an important issue to suppress the manufacturing cost of the 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.

  As a method for removing a thin film on a glass substrate, a method using a thin film etchant is generally used. For example, in Patent Document 1, at least one of ammonium hydrogen fluoride, ammonium fluoride, hydrofluoric acid, and boron fluoride is used as an etchant for a light-shielding film containing a metal silicide such as molybdenum silicide. And using an aqueous solution in which at least one of hydrogen peroxide and nitric acid is mixed. Using such an etchant, a thin film containing a metal silicide on a substrate is removed by etching. It is possible. In addition, a thin film containing a metal silicide such as molybdenum silicide can be removed using hydrofluoric acid.

JP 62-218585 A JP 2002-4052 A

However, the method for removing a thin film containing a metal silicide such as molybdenum silicide on a glass substrate using an etchant or hydrofluoric acid as described in Patent Document 1 has the following problems. .
That is, since glass as a substrate material is soluble in the etchant and hydrofluoric acid described in Patent Document 1, an altered layer due to white turbidity is formed on the substrate surface after the thin film is removed, or polishing is performed with high smoothness. It is inevitable that damage such as an increase in the surface roughness of the substrate surface will occur.

  In order to completely remove such damage and regenerate the substrate, 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 other words, even if the substrate is regenerated by the conventional method, it cannot be said that it is sufficient for solving the problem of suppressing the manufacturing cost of the transfer mask.

In Patent Document 2, a deposited film attached to the inner wall of a reaction vessel in a deposition apparatus that forms a deposited film such as amorphous silicon on a substrate is used as a cleaning gas containing at least ClF ₃ or a plasma of the cleaning gas. Is disclosed. However, when plasma is used to increase the cleaning speed, there is a concern about the occurrence of damage due to plasma. In the mask blank substrate regeneration, it is desired to suppress the deterioration of the substrate surface after removing the thin film and to suppress the deterioration of the surface roughness. Therefore, the deposition attached to the inner wall of the reaction vessel as in Patent Document 2 above. It is not possible to simply apply the same method as when the film is simply removed.

  Further, the thin film material of the mask blank is not limited to the metal silicide such as the above-mentioned molybdenum silicide, but various kinds of thin film materials are known depending on the type of the mask blank, and a release agent ( It is possible to regenerate the substrate by removing the thin film on the substrate using an etchant or the like. However, even when these thin film materials are different, it is desirable that the thin film can be removed and the substrate can be regenerated using the same method if possible. Further, the thin film of the mask blank is often composed of a plurality of layers. In this case, even when the materials of the respective layers are different, when the substrate is regenerated, the entire thin film of the plurality of layers is simultaneously removed from the substrate. It is desirable to be able to remove and remove.

  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 also have high added value. Many expensive base materials have been 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 situation. The purpose of the present invention is, firstly, that there is little damage to the substrate after removal of the thin film, and the process load of re-polishing is also small. The present invention provides a method for regenerating a substrate that can reduce the cost of regenerating the substrate. Second, a method for manufacturing a mask blank that uses a substrate regenerated by this regenerating method, a method for manufacturing a substrate with a multilayer reflective film, and It is to provide a method for manufacturing a reflective mask blank.

  As a result of intensive investigations to solve the above problems, the present inventor has removed the thin film on the substrate by bringing it into contact with a non-excited substance containing a specific fluorine-based compound, thereby removing the substrate after removing the thin film. I found that I could reduce the damage. In addition, the above method can particularly reduce the damage to the substrate after removing the thin film when the thin film is formed of a material that can be dry-etched with a fluorine-based gas, such as a material containing silicon, and is suitable for substrate regeneration. I also found out.

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 mask blank provided with a thin film for pattern formation on a main surface of a substrate made of glass or a method of regenerating a substrate by removing the thin film of a transfer mask produced using the mask blank, the mask blank Alternatively, the thin film of the transfer mask is in an unexcited state containing a compound of fluorine (F) and any element of chlorine (Cl), bromine (Br), iodine (I), and xenon (Xe). A method for regenerating a substrate, wherein the substrate is removed by contact with the material.

(Configuration 2)
The method for regenerating a substrate according to Configuration 1, wherein the thin film is formed of a single layer or a plurality of layers, and at least a layer in contact with the substrate is formed of a material that can be dry-etched with a fluorine-based gas. .
(Configuration 3)
The layer in contact with the substrate is formed of any one of a material containing silicon (Si), a material containing metal and silicon (Si), and a material containing tantalum (Ta). The method for regenerating a substrate according to Configuration 2.

(Configuration 4)
4. The substrate recycling method according to any one of Structures 1 to 3, wherein the substrate is made of synthetic quartz glass.
(Configuration 5)
A mask blank manufacturing method, comprising: forming a thin film for pattern formation on a substrate regenerated by the substrate regenerating method according to any one of Structures 1 to 4.

(Configuration 6)
A method for regenerating a substrate by removing the multilayer reflective film of a substrate with a multilayer reflective film comprising a multilayer reflective film having a structure in which a low refractive index layer and a high refractive index layer are alternately laminated on a main surface of a substrate made of glass Wherein the multilayer reflective film of the substrate with the multilayer reflective film is formed of any one element of chlorine (Cl), bromine (Br), iodine (I), and xenon (Xe) and fluorine (F) A method for regenerating a substrate, wherein the substrate is removed by contact with a non-excited substance containing the compound.

(Configuration 7)
7. The method for regenerating a substrate according to Configuration 6, wherein the low refractive index layer is made of silicon (Si) and is in contact with the main surface of the substrate.
(Configuration 8)
8. The substrate recycling method according to Configuration 6 or 7, wherein the substrate is made of SiO ₂ —TiO ₂ low thermal expansion glass.

(Configuration 9)
A multilayer reflective film having a structure in which a low refractive index layer and a high refractive index layer are alternately laminated is formed on a substrate regenerated by the substrate regenerating method according to any one of Structures 6 to 8. It is a manufacturing method of a board | substrate with a multilayer reflective film.

(Configuration 10)
A reflective mask blank comprising a multilayer reflective film having a structure in which a low refractive index layer and a high refractive index layer are alternately laminated on a main surface of a glass substrate, and an absorber film for pattern formation, or the reflection A method of regenerating a substrate by removing the multilayer reflective film of a reflective mask manufactured using a mold mask blank, wherein the reflective mask blank or the multilayer reflective film of the reflective mask is made of chlorine (Cl ), Bromine (Br), iodine (I), and xenon (Xe), and a non-excited substance containing a compound of fluorine (F) and the element is removed. A method for regenerating a substrate.

(Configuration 11)
11. The method for regenerating a substrate according to Configuration 10, wherein the low refractive index layer is made of silicon (Si) and is in contact with the main surface of the substrate.
(Configuration 12)
12. The substrate recycling method according to Configuration 10 or 11, wherein the substrate is made of SiO ₂ —TiO ₂ low thermal expansion glass.

(Configuration 13)
A multilayer reflective film having a structure in which a low refractive index layer and a high refractive index layer are alternately laminated on a substrate regenerated by the substrate regenerating method according to any one of Structures 10 to 12, and an absorber for pattern formation It is a manufacturing method of the reflective mask blank characterized by forming a film | membrane in order.

(Configuration 14)
In a mask blank having a thin film for pattern formation on the main surface of a substrate made of glass, the thin film of the mask blank corresponding to a method for producing an imprint mold in which the thin film and the substrate are etched by dry etching is removed. Then, the substrate is regenerated, and the thin film of the mask blank is made of any one element of chlorine (Cl), bromine (Br), iodine (I), and xenon (Xe) with fluorine (F And a substrate in a non-excited state containing the compound, and removing the substrate.

(Configuration 15)
15. The method for regenerating a substrate according to Configuration 14, wherein the thin film is composed of a single layer or a plurality of layers, and at least a layer in contact with the substrate is formed of a material containing tantalum (Ta) as a main component. is there.
(Configuration 16)
16. The substrate recycling method according to Configuration 14 or 15, wherein the substrate is made of synthetic quartz glass.

(Configuration 17)
A mask blank manufacturing method, comprising: forming a thin film for pattern formation on a substrate regenerated by the substrate regenerating method according to any one of Structures 14 to 16.

  According to the present invention, glass as a substrate material is easily etched by dry etching with an excited fluorine-based gas, but has a characteristic that it is difficult to etch a non-excited fluorine-based compound. Therefore, damage to the substrate after removal of the thin film can be reduced, and the process load for re-polishing can be reduced, so that the cost for regenerating the substrate can be reduced. In addition, according to the present invention, a high-quality substrate can be reproduced at low cost, and therefore, it is particularly suitable for mask blank substrate regeneration using an expensive base material having high added value.

  Further, according to the present invention, a mask blank using a high-quality regenerated substrate can be manufactured at low cost by forming a thin film for pattern formation on the substrate regenerated by the regenerating method according to the present invention. In addition, by forming a multilayer reflective film having a structure in which a low refractive index layer and a high refractive index layer are alternately laminated, an absorber film for pattern formation, and the like on the substrate, a high quality reproduction substrate can be obtained. A substrate with a multilayer reflective film or a reflective mask blank to be used can be manufactured at low cost.

It is a schematic block diagram of the processing apparatus used at the process of removing a thin film.

Hereinafter, embodiments of the present invention will be described in detail.
[First Embodiment]
In the first embodiment of the present invention, a substrate is formed by removing the thin film of a mask blank provided with a thin film for pattern formation on the main surface of a substrate made of glass or a transfer mask produced using the mask blank. In which the mask blank or the thin film of the transfer mask is any one of chlorine (Cl), bromine (Br), iodine (I), and xenon (Xe). A method for regenerating a substrate, wherein the substrate is removed by contact with a non-excited substance containing a compound of element and fluorine (F).

  The mask blank in the present embodiment is a mask blank including a thin film for pattern formation on the main surface of the substrate. Specifically, the binary mask blank having a structure including a light-shielding film on the main surface of the substrate, A phase shift mask blank having a structure including a phase shift film or a phase shift film and a light-shielding film on the main surface of the substrate may be mentioned. Also provided is a light semi-transmissive film having characteristics that transmit light of intensity that does not substantially contribute to exposure but does not give a phase difference that causes a phase shift effect, or the light semi-transmissive film and the light-shield film. A mask blank having a structure is mentioned. Furthermore, the mask blank of the structure which equips the uppermost layer of these mask blanks with an etching mask film | membrane etc. are mentioned. In addition, the present invention can also be applied to a mask blank used for a multi-tone mask used in manufacturing an FPD (flat panel display) device. Examples of the mask blank include a structure in which a light semi-transmissive film and a light shielding film are stacked on a glass substrate.

  This 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 and the light semi-transmissive film may be a single layer or a plurality of layers.

In the method for regenerating a substrate according to the present invention, the thin film is made of a fluorine-based gas (for example, SF ₆ , CF ₄ , C ₂ F ₆ , CHF _3, etc., or these and He, Ar, N ₂ , C ₂ H ₄ , O It is suitable for regenerating a mask blank substrate formed of a material that can be dry-etched with a mixed gas of ₂ ). The glass substrate has a characteristic that it is easily etched by a fluorine-based gas plasma in an excited state used in dry etching, but is not easily etched by a non-excited fluorine-based compound substance. On the other hand, a material that can be dry-etched with a fluorine-based gas used in a thin film has a characteristic that it is easily etched even with a non-excited fluorine-based compound. That is, a material that can be dry-etched with a fluorine-based gas is particularly effective in that sufficient etching selectivity is easily obtained with respect to a non-excited fluorine-based compound, and damage to the substrate due to thin film peeling can be reduced. Easy to obtain.

  Examples of the material that can be dry-etched with this fluorine-based gas include a material containing silicon (Si), a material containing transition metal and silicon (Si), a material containing metal and silicon (Si), and tantalum ( Examples thereof include materials containing Ta). As a mask blank using such a material, for example, a binary mask blank having a light shielding film formed of a material containing a transition metal and silicon (Si), or a material containing tantalum (Ta) is used. A binary mask blank including a light shielding film, a phase shift mask blank including a phase shift film formed of a material containing silicon (Si), or a material containing a transition metal and silicon (Si). .

  As the material containing silicon (Si), a material further containing at least one element of nitrogen, oxygen, and carbon, specifically, a silicon nitride, an oxide, a carbide, an oxynitride, A material containing a carbonate or carbonitride is preferred.

  Moreover, as the material containing the transition metal and silicon (Si), in addition to the material containing the transition metal and silicon, the material further contains at least one element of nitrogen, oxygen and carbon in addition to the transition metal and silicon. Is mentioned. 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, chromium, hafnium, nickel, vanadium, zirconium, ruthenium, rhodium, niobium, yttrium, lanthanum, palladium, iron, and the like are applicable. Of these, molybdenum is particularly preferred.

  Examples of the material containing metal and silicon (Si) include a material containing at least one element of nitrogen, oxygen, and carbon in addition to metal and silicon, in addition to the material containing metal and silicon. . The material containing metal and silicon (Si) includes the material containing the transition metal and silicon (Si). As the metal, germanium, gallium, aluminum, indium, tin, and the like can be applied in addition to the transition metal.

  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 the method for regenerating a substrate according to the present invention, when a thin film such as a light shielding film in a binary mask blank or a phase shift film in a phase shift mask blank is composed of a plurality of layers, at least the layer in contact with the substrate , Materials that can be dry etched with a fluorine-based gas, such as materials containing silicon (Si), materials containing transition metals and silicon (Si), materials containing metals and silicon (Si), and tantalum (Ta It is suitable for the reproduction | regeneration of the board | substrate of the mask blank currently formed with either of the materials containing).

  The mask blank substrate is not particularly limited as long as it has transparency with respect to the exposure wavelength to be used, and a synthetic quartz substrate and other various glass substrates (for example, soda lime glass, aluminosilicate glass, etc.). Among them, the synthetic quartz substrate is particularly preferably used because of its high transparency in an ArF excimer laser or a shorter wavelength region.

  The method for regenerating a substrate according to the present invention includes a mask blank having a thin film for pattern formation on the main surface of the substrate as described above, or the thin film of a transfer mask produced by a mask processing technique using the mask blank. , In contact with a non-excited substance containing a compound of fluorine (F) with any one element of chlorine (Cl), bromine (Br), iodine (I), and xenon (Xe) This is a method for regenerating a substrate.

Between the glass substrate and the thin film for pattern formation (especially a thin film made of a material that can be dry-etched with a fluorine-based gas), it was excited by etching with an excited fluorine-based gas plasma or irradiation with charged particles. Etching selectivity is difficult to obtain by etching with a fluorine-based gas. On the other hand, a high etching selectivity can be obtained between the glass substrate and the pattern forming thin film for the non-excited fluorine-based compound substance. The non-excited fluorine-based compound is preferably brought into contact in a fluid state, and particularly preferably in a gas state.
On the other hand, hydrofluoric acid solution and silicic hydrofluoric acid solution containing hydrogen ions cause the action of hydrogen ions to break the bond of Si-O in the glass, so that fluorine and silicon are easily bonded. It is difficult to obtain the effects of the invention. Considering this point, it is desirable that the non-excited fluorine-based substance does not substantially contain hydrogen.

A compound of any element of chlorine (Cl), bromine (Br), iodine (I), and xenon (Xe) and fluorine (F) used in the present invention (hereinafter simply referred to as “the compound of the present invention”). For example, ClF ₃ , ClF, BrF ₅ , BrF, IF ₃ , IF ₅ , XeF ₂ , XeF ₄ , XeF ₆ , XeOF ₂ , XeOF ₄ , XeO ₂ F ₂ , XeO ₃ F _{2 can be used.} Or a compound such as XeO ₂ F ₄ can be preferably used. Among these, ClF ₃ can be particularly preferably used in the present invention.

  As a method for bringing the thin film of a mask blank or a transfer mask produced using the mask blank into contact with a non-excited substance containing the compound of the present invention, for example, a mask blank is placed in a chamber, and the chamber A method of introducing a substance containing the compound of the present invention into a gas state therein and replacing the inside of the chamber with the gas is preferred.

In the present invention, when a substance containing the compound of the present invention is used in a gas state, the compound of the present invention and nitrogen gas, or argon (Ar), helium (He), neon (Ne), krypton (Kr), xenon ( A mixed gas with Xe), radon (Rn) or the like (hereinafter simply referred to as argon (Ar) or the like) can be used. In the present invention, when a substance containing the compound of the present invention is used in a gas state, a mixed gas of the compound of the present invention and argon (Ar) can be preferably used.
The processing conditions when the thin film of the mask blank or transfer mask is brought into contact with a non-excited gas state substance containing the compound of the present invention, such as gas flow rate, gas pressure, temperature, and processing time, need to be particularly restricted. However, from the viewpoint of preferably obtaining the action of the present invention, it is desirable to select appropriately according to the material of the thin film and the number of layers (film thickness).

  As for the gas flow rate, for example, when a mixed gas of the compound of the present invention and argon is used, it is preferable that the compound of the present invention is mixed in a flow rate ratio of 1% or more. When the flow rate of the compound of the present invention is less than the above flow rate ratio, the progress of peeling of the thin film is delayed, resulting in a longer treatment time and difficulty in peeling.

  The gas pressure is preferably selected as appropriate in the range of 100 to 760 Torr, for example. When the gas pressure is lower than the above range, the gas amount itself of the compound of the present invention in the chamber is too small, and the progress of peeling of the thin film is delayed. As a result, the treatment time becomes long and peeling becomes difficult. On the other hand, if the gas pressure is higher than the above range (above atmospheric pressure), the gas may flow out of the chamber, and the compound of the present invention includes a highly toxic gas, which is not preferable.

  Moreover, it is preferable to select suitably about the temperature of gas, for example in 20-500 degreeC. When the temperature is lower than the above range, the progress of the peeling of the thin film is delayed, resulting in a longer treatment time and difficulty in peeling. On the other hand, if the temperature is higher than the above range, peeling progresses quickly and the processing time can be shortened, but the selectivity between the thin film and the substrate is difficult to obtain, and the substrate damage may be slightly increased.

  Furthermore, the processing time may be basically a time sufficient for the thin film to be peeled and removed from the substrate. In the case of the present invention, although depending on the gas flow rate, gas pressure, and temperature described above, or depending on the material and film thickness of the thin film, the processing time is generally in the range of 5 to 30 minutes, and the effects of the present invention are preferably obtained. .

FIG. 1 is a schematic configuration diagram of a processing apparatus suitable for use in the process of removing the thin film.
This processing apparatus includes gas filling containers 13 and 14, flow rate controllers 15 and 16, an ejection nozzle 17, and connection pipes thereof, and a non-excited gas supply machine is configured. A processing substrate 11 such as a mask blank is placed on a stage 12 in a chamber 10 of the processing apparatus. Then, for example, the gas in the two kinds of gas filling containers 13 and 14 is mixed after the flow rate is adjusted by the flow rate controllers 15 and 16, and then mixed, ejected from the ejection nozzle 17 and introduced into the chamber 10. Further, the gas in the chamber 10 passes through the exhaust pipe 18 and is appropriately exhausted after being detoxified by the exhaust gas processing device 19.
When the substance containing the fluorine-based compound of the present invention is used in a gas state, the above two types of gases are the fluorine-based compound of the present invention and nitrogen gas, or a rare gas such as argon (Ar).

  The chamber 10 of the processing apparatus has a horizontal apparatus configuration and is suitable for single wafer processing. On the other hand, as a configuration of a chamber suitable for batch processing for processing a large number of substrates at a time, for example, the following configuration can be considered. The chamber is vertically long and a heating device is arranged on the outer periphery of the chamber so that the inside of the chamber can be heated. Further, a vertically long shelf made of a heat-resistant material such as synthetic quartz is arranged inside the chamber so that a plurality of processing substrates can be arranged vertically at intervals in the chamber.

In general, a chromium-based material (Cr, CrO, CrN, CrC, CrON, CrCN, CrOC, CrOCN, etc.) that does not contain silicon is also used as a thin film for mask blank pattern formation. In the case of these thin films, a conventional method for removing a chromium-based material may be used, a method of supplying the compound of the present invention at a high temperature, a compound of the present invention in a gas state, oxygen (O ₂ ) gas, You may use the method of supplying with these mixed gas. In the case of a method of supplying the compound of the present invention at a high temperature to a thin film of a chromium-based material, the supply conditions include, for example, a concentration of the compound of the present invention in the supply gas (concentration at a gas flow ratio) of 90%. As described above, it is more preferable that the surface temperature of the object to be processed is 280 ° C. to 350 ° C., more preferably 100%. Further, it is desirable that the treatment time is 5 minutes or more, more preferably 6 minutes or more, the pressure in the chamber is about 1 kPa, and the supply gas flow rate is about 300 sccm.

  In a binary mask blank using a thin film made of a material containing a transition metal and silicon as a light shielding film, a thin film of a chromium-based material may be used as an etching mask film on the light shielding film. Also, a phase shift mask blank using a thin film made of a material containing transition metal and silicon as a phase shift film, and a thin film of a chromium-based material is used as a light shielding film for forming a light shielding band on the phase shift film. Sometimes. In addition, a mask blank that uses a thin film made of a material containing transition metal and silicon as a light semi-transmissive film, and a thin film of a chromium-based material is used as a light shielding film for forming a light shielding band on the light semi-transmissive film. There is. Further, there is a mask blank having a structure in which a thin film made of a material that can be dry-etched with a fluorine-based gas is stacked as an etching mask film on a light shielding film of a chromium-based material. In these cases, the above-described method or a conventional method for removing a chromium-based material can be used for removing the thin film of the chromium-based material.

According to the method for regenerating a substrate according to the present invention, a thin film such as a mask blank is brought into contact with a non-excited (preferably non-excited, gas-state) substance containing the compound of the present invention, and thereby a glass substrate (particularly Since high etching selectivity is obtained with respect to the synthetic quartz substrate), damage to the substrate after removal of the thin film can be reduced.
Thus, after removing the thin film from the mask blank, the surface of the substrate is precisely polished for a short time, so that the surface roughness of the highly smooth substrate before the thin film removal can be recovered. The substrate regeneration method according to the present invention has less damage on the substrate surface due to the removal of the thin film, and therefore requires less polishing allowance when re-polishing, and is the final stage of a plurality of stages of polishing processes from rough polishing to precision polishing. It becomes possible to return to (precision polishing). Therefore, the process load of re-polishing is reduced, so that the cost for regenerating the substrate can be reduced, and a high-quality substrate can be regenerated. According to the present invention, since a high-quality substrate can be reproduced at low cost, 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 can be produced at low cost 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 sputtering film forming method. Can be manufactured.

[Second Embodiment]
In the second embodiment of the present invention, the multilayer of the substrate with a multilayer reflective film comprising a multilayer reflective film having a structure in which a low refractive index layer and a high refractive index layer are alternately laminated on a main surface of a substrate made of glass. The present invention relates to a method for regenerating a substrate by removing a reflective film, wherein the multilayer reflective film of the substrate with the multilayer reflective film is made of chlorine (Cl), bromine (Br), iodine (I), and xenon (Xe ) In contact with a non-excited substance containing a compound of any one of the above elements and fluorine (F).

  In recent years, in the semiconductor industry, with the miniaturization of semiconductor devices, EUV lithography, which is an exposure technique using extreme ultraviolet (hereinafter referred to as EUV) light, is promising. Here, EUV light refers to light in the wavelength band of the soft X-ray region or the vacuum ultraviolet region, and specifically refers to light having a wavelength of about 0.2 to 100 nm. A reflective mask has been proposed as a mask used in this EUV lithography. In such a reflective mask, a multilayer reflective film that reflects exposure light is formed on a substrate, and an absorber film that absorbs exposure light is formed in a pattern on the multilayer reflective film.

  The substrate with a multilayer reflective film is a reflective mask blank for manufacturing the reflective mask, that is, a multilayer reflective film that reflects exposure light on the substrate, and an absorber film for pattern formation that absorbs the exposure light. Can be used as a substrate for a reflective mask blank. Then, after forming a multilayer reflective film on the substrate, a substrate with a multilayer reflective film in which subsurface defects etc. are found by surface defect inspection cannot be used as a substrate for a reflective mask blank. It is desirable to regenerate the substrate by removing the film.

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. In addition, as a multilayer reflective film used in the EUV light region, Ru / Si periodic multilayer film, Mo / Be periodic multilayer film, Mo compound / Si compound periodic multilayer film, Si / Nb periodic multilayer film, Si / Mo / Examples include Ru periodic multilayer films, Si / Mo / Ru / Mo periodic multilayer films, and Si / Ru / Mo / Ru periodic multilayer films. The material may be appropriately selected depending on the exposure wavelength.

Further, the glass substrate is preferably in the range of 0 ± 1.0 × 10 ⁻⁷ / ° C., more preferably 0 ± 0.3 × 10 ⁻⁷ / ° C., in order to prevent distortion of the pattern due to heat during exposure. A material having a low thermal expansion coefficient within the range is preferably used, and as a material having a low thermal expansion coefficient within this range, for example, if it is amorphous glass, it may be SiO ₂ —TiO ₂ glass, quartz glass, or crystallized glass. For example, crystallized glass or the like on which β quartz solid solution is deposited can be used. Further, in order to obtain high reflectivity and high transfer accuracy, a substrate having high smoothness and flatness is preferable. In particular, it is preferable to have a smooth surface of 0.15 nm Rq or less (smoothness in a 10 μm square area) and a flatness of 50 nm or less (flatness in a 142 mm square area). In addition, unit Rq which shows smoothness is a root mean square roughness, and can be measured with an atomic force microscope. Further, the flatness is a value representing the warpage (deformation amount) of the surface indicated by TIR (Total Indicated Reading), and a plane determined by the least square method with respect to the substrate surface is a focal plane, and is above the focal plane. This is the absolute value of the height difference between the highest position on the substrate surface and the lowest position on the substrate surface below the focal plane.

The method for regenerating a substrate according to the present invention includes a multilayer reflective film in which the low refractive index layer such as the Mo / Si periodic laminated film is made of silicon (Si) and is in contact with the main surface of the substrate. It is suitable for recycling the substrate of the substrate. Moreover, the method for regenerating a substrate according to the present invention is suitable for regenerating a substrate having a multilayer reflective film in which the substrate such as the SiO ₂ —TiO ₂ glass is made of low thermal expansion glass. In particular, in the case of SiO ₂ —TiO ₂ -based low thermal expansion glass, if the multilayer reflective film on the main surface of the substrate is peeled off with a hydrofluoric acid solution or a silicic hydrofluoric acid solution, Ti will come off the substrate, resulting in surface roughness. In particular, the substrate recycling method according to the present invention is effective.

  Also in the substrate with a multilayer reflective film of the present embodiment, the substrate can be regenerated by removing the multilayer reflective film of the substrate with the multilayer reflective film in contact with a non-excited substance containing the compound of the present invention. it can.

As the compound of the present invention used in this embodiment, that is, a compound of any element of chlorine (Cl), bromine (Br), iodine (I), and xenon (Xe) and fluorine (F) Is the same as in the first embodiment described above, for example, ClF ₃ , ClF, BrF ₅ , BrF, IF ₃ , IF ₅ , XeF ₂ , XeF ₄ , XeF ₆ , XeOF ₂ , XeOF ₄ , XeO _2. A compound such as F ₂ , XeO ₃ F ₂ , or XeO ₂ F ₄ can be preferably used, and ClF ₃ can be particularly preferably used.

As a method for bringing the multilayer reflective film into contact with a non-excited substance containing the compound of the present invention, a mask blank is placed in the chamber and the compound of the present invention is placed in the chamber, as in the first embodiment. A method of introducing a substance containing a gas in a gas state and replacing the inside of the chamber with the gas is preferable. Further, as in the first embodiment described above, the multilayer reflective film on the glass substrate may be removed using the processing apparatus shown in FIG. Also in this embodiment mode, when a substance containing the compound of the present invention is used in a gas state, a mixed gas of the compound of the present invention and nitrogen gas, argon (Ar), or the like can be used. Also in this embodiment, when a substance containing the compound of the present invention is used in a gas state, a mixed gas of the compound of the present invention and argon (Ar) can be preferably used.
Regarding preferable processing conditions when the multilayer reflective film is brought into contact with a non-excited gas state substance containing the compound of the present invention, for example, preferable conditions of gas flow rate, gas pressure, temperature, and processing time, the first embodiment described above is used. Although it is substantially the same as the case of the form, it is desirable to select appropriately according to the material and the number of layers (film thickness) of the multilayer reflective film.

According to the method for regenerating a substrate according to the present invention, a substrate made of glass (particularly low thermal expansion glass) is obtained by bringing the multilayer reflective film of the substrate with the multilayer reflective film into contact with a non-excited substance containing the compound of the present invention. High etching selectivity with respect to the substrate) can be obtained, so that damage to the substrate after removal of the multilayer reflective film can be reduced.
In this way, after removing the multilayer reflective film from the substrate with the multilayer reflective film, the surface of the substrate is re-polished to restore the surface roughness of the highly smooth substrate before removing the multilayer reflective film. The method for regenerating a substrate according to the present invention has less damage on the surface of the substrate due to the removal of the multilayer reflective film, and therefore requires less polishing allowance when re-polishing. Of the multiple stages of polishing steps from rough polishing to precise polishing, It becomes possible to return to the final stage (precision polishing). Therefore, the process load of re-polishing is reduced, so that the cost for regenerating the substrate can be reduced, and a high-quality substrate can be regenerated. According to the present invention, since a high-quality substrate can be reproduced at low cost, it is particularly suitable for regenerating a substrate with a multilayer reflective film using an expensive base material with high added value.

  The present invention also provides a method for manufacturing a substrate with a multilayer reflective film, which uses a substrate regenerated by this regenerating method. A multilayer reflection having a structure in which a low refractive index layer and a high refractive index layer are alternately laminated again on the substrate regenerated by the reproducing method according to the present invention by using, for example, a DC magnetron sputtering method or an ion beam sputtering method. By forming the film, a substrate with a multilayer reflective film that uses a high-quality recycled substrate can be manufactured at low cost.

  Further, the present invention is suitable not only for regenerating the substrate with the multilayer reflective film but also for regenerating the substrate with the reflective mask blank. That is, a reflective mask blank comprising a multilayer reflective film having a structure in which a low refractive index layer and a high refractive index layer are alternately laminated on a main surface of a substrate, and an absorber film for pattern formation, or the reflective type The substrate can be regenerated by removing the multilayer reflective film of the reflective mask produced using the mask blank by bringing it into contact with a non-excited substance containing the compound of the present invention.

  The absorber film has a function of absorbing exposure light such as EUV light. For example, tantalum (Ta) alone or a material containing Ta as a main component 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 Material containing Si and N, Material containing Ta and Ge, Material containing Ta, Ge and N, Material containing Ta and Hf, Material containing Ta, Hf and N, Material containing Ta, Hf and O, Ta And a material containing Zr, a material containing Ta, Zr and N, a material containing Ta, Zr and O, or the like is used.

  Usually, in order to protect the multilayer reflective film, a protective film or a buffer film is provided between the multilayer reflective film and the absorber film. In addition to silicon, ruthenium, and ruthenium compounds containing one or more elements of niobium, zirconium, and rhodium in ruthenium are used as the material for the protective film. The material for the buffer film is mainly the above-described chromium-based material. Is used.

According to the present invention, in the case of such a reflective mask blank or a reflective mask, the multilayer reflective film and an absorber film laminated thereon (a protective film and an absorber film when a protective film is provided) are provided. It is possible to remove together.
Even when the reflective mask blank or the substrate of the reflective mask is regenerated, when a substance containing the compound of the present invention is used in a gas state, a mixed gas of the compound of the present invention and nitrogen gas, argon (Ar), or the like. Can be used. Even when the reflective mask blank or the substrate of the reflective mask is regenerated, a mixed gas of the aforementioned compound of the present invention and argon (Ar) can be preferably used. Preferred processing conditions when a multilayer reflective film such as a reflective mask blank is brought into contact with a non-excited gaseous substance containing the compound of the present invention, for example, preferred conditions for gas flow rate, gas pressure, temperature, and processing time are described above. This is almost the same as the case of the substrate with a multilayer reflective film.

  For reflective mask blanks and reflective masks that use a chromium-based material for the absorber film, or that have a buffer film made of a chromium-based material, removal of the absorber film and buffer film of the chromium-based material The above-described method and a conventional chromium-based material removal method may be used.

  According to the method for regenerating a substrate according to the present invention, a glass substrate (particularly a low thermal expansion glass substrate) is obtained by bringing a multilayer reflective film such as the reflective mask blank into contact with a non-excited substance containing the compound of the present invention. Therefore, it is possible to reduce damage to the substrate after removing the multilayer reflective film and the laminated film (absorber film or protective film and absorber film) thereon. In the substrate regeneration method according to the present invention, the damage on the substrate surface due to the removal of the multilayer reflective film or the like is thus small, so that the process load of re-polishing is reduced, the substrate regeneration cost can be reduced, and high quality is achieved. The substrate can be regenerated.

  The present invention also provides a method for manufacturing a reflective mask blank using a substrate regenerated by this regenerating method. A multilayer reflective film having a structure in which a low refractive index layer and a high refractive index layer are alternately laminated on a substrate reproduced by the reproducing method according to the present invention by using, for example, a DC magnetron sputtering method or an ion beam sputtering method. A reflective mask blank that uses a high-quality reproduction substrate by forming a protective film and an absorber film for pattern formation (or a buffer film and an absorber film) on the substrate by magnetron sputtering or the like. Can be manufactured at low cost.

  In addition, the reflective mask blank or reflective mask to be processed is made of a chromium-based material for the protective film on the multilayer reflective film, and a non-chromium-based material (tantalum or tantalum as the main component) for the absorber film. It is also possible to remove only the absorber film. In this case, the concentration of the compound of the present invention in the supply gas (concentration at the gas flow ratio) is 80% or more, more preferably 90% or more, and the surface temperature of the absorber film is 180 ° C. to 220 ° C. Good. Further, it is desirable that the treatment time is 5 minutes or longer, more preferably 7 minutes or longer, and the pressure in the chamber is 490 to 510 Torr. Thereby, the substrate with a multilayer reflective film can be regenerated from the reflective mask blank or the reflective mask. Furthermore, a reflective mask blank can be manufactured by forming an absorber film again on the regenerated substrate with a multilayer reflective film.

[Third Embodiment]
In the third embodiment of the present invention, in a mask blank including a thin film for pattern formation on a main surface of a substrate made of glass, an imprint mold for etching the thin film and the substrate by a dry etching process is manufactured. A method of regenerating a substrate by removing the thin film of a mask blank corresponding to a method, wherein the thin film of the mask blank is made of chlorine (Cl), bromine (Br), iodine (I), and xenon A method for regenerating a substrate, comprising removing an element in contact with a non-excited substance containing a compound of any element of (Xe) and fluorine (F).

  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 having a thin film for pattern formation on a glass substrate such as synthetic quartz glass is used. A desired resist pattern is formed on the mask blank, and the thin film is etched by using the resist pattern as a mask to form a thin film pattern (mask pattern). Further, the substrate is etched by using the thin film pattern as a mask. And the mold for imprint is produced by forming a level | step difference pattern in a translucent board | substrate.

The present invention is also suitable for regenerating a mask blank substrate corresponding to such a method for producing an imprint mold.
In the method for regenerating a substrate according to the present invention, the thin film in the mask blank is composed of a single layer or a plurality of layers, and at least the layer in contact with the substrate is formed of a material mainly composed of tantalum (Ta). It is particularly suitable for substrate regeneration. As such a mask blank, for example, the thin film is composed of at least an upper layer and a lower layer, the upper layer is formed of a material containing Cr as a main component, and the lower layer is formed of a material containing tantalum (Ta) as a main component. An example is a mask blank in which these thin films can be etched by a dry etching process using a chlorine-based gas.

  The material mainly composed of tantalum is, for example, a Ta compound such as TaHf, TaZr, or TaHfZr, or a material obtained by adding a sub-material such as B, Ge, Nb, Si, C, or N using these Ta compounds as a base material. and so on. However, a material containing Ta as a main component has a characteristic of being easily oxidized when it comes into contact with a gas containing oxygen. Ta-based materials excluding TaHf, TaZr, and TaHfZr as main components can be etched with both excited chlorine-based gas and excited fluorine-based gas. The material used as a component becomes difficult to etch by dry etching using an excited state chlorine-based gas, and can be etched only by an excited state fluorine-based gas. In this case, the fluorine gas makes it difficult to obtain etching selectivity with the glass substrate, and damage to the glass substrate after peeling increases, so that the effect of the present invention is very great.

  Further, a material mainly composed of TaHf, TaZr, and TaHfZr can be etched with an excited chlorine-based gas, but is difficult to etch with an excited fluorine-based gas. These materials are also easily oxidized, and when oxidized, etching becomes difficult even with an excited chlorine-based gas. In this case, it becomes difficult to obtain etching selectivity with a chlorine-based gas with respect to the glass substrate, and damage to the glass substrate after peeling increases, so the effect of the present invention is very great.

  As the mask blank substrate, a synthetic quartz substrate and other various glass substrates (for example, soda lime glass, aluminosilicate glass, etc.) are used, and among these, a synthetic quartz substrate is particularly preferably used.

  Also in the mask blank corresponding to the method for manufacturing the imprint mold of the present embodiment, the substrate is regenerated by removing the thin film of the mask blank in contact with a non-excited substance containing the compound of the present invention. be able to.

The compound of the present invention used in this embodiment, that is, a compound of any element of chlorine (Cl), bromine (Br), iodine (I), and xenon (Xe) and fluorine (F) In the same manner as in the first embodiment, for example, ClF ₃ , ClF, BrF ₅ , BrF, IF ₃ , IF ₅ , XeF ₂ , XeF ₄ , XeF ₆ , XeOF ₂ , XeOF ₄ , XeO _{2 are used.} A compound such as F ₂ , XeO ₃ F ₂ , or XeO ₂ F ₄ can be preferably used, and ClF ₃ can be particularly preferably used.

  Also in the present embodiment, as a method of bringing the mask blank thin film into contact with the non-excited substance containing the compound of the present invention, the mask blank is placed in the chamber, as in the first embodiment described above. A method of introducing a substance containing the compound of the present invention into the chamber in a gas state and replacing the inside of the chamber with the gas is preferred. Further, as in the first embodiment described above, the mask blank thin film may be removed using the processing apparatus shown in FIG. Also in this embodiment mode, when a substance containing the compound of the present invention is used in a gas state, a mixed gas of the compound of the present invention and nitrogen gas, argon (Ar), or the like can be used. Also in this embodiment, when a substance containing the compound of the present invention is used in a gas state, a mixed gas of the compound of the present invention and argon (Ar) can be preferably used. Regarding the preferable processing conditions when the mask blank thin film is brought into contact with the non-excited gas state substance containing the compound of the present invention, for example, the preferable conditions of the gas flow rate, gas pressure, temperature, and processing time, the first implementation described above. However, it is desirable to select appropriately depending on the material of the thin film and the number of layers (film thickness).

According to the method for regenerating a substrate according to the present invention, the thin film of the mask blank corresponding to the method for producing an imprint mold is contacted with a non-excited substance containing the compound of the present invention to remove it from the glass. Since high etching selectivity is obtained with a substrate (especially a synthetic quartz glass substrate) to be formed, damage to the substrate after removal of the thin film can be reduced.
As described above, also in the present embodiment, since the damage on the substrate surface due to the removal of the thin film is small, the re-polishing process load is also reduced, so that the cost for regenerating the substrate can be reduced, and a high-quality substrate can be obtained. Can be played.

  The present invention also provides a mask blank manufacturing method corresponding to the imprint mold manufacturing method using the substrate regenerated by this regenerating method. That is, a thin film for pattern formation is formed again on the substrate regenerated by the regenerating method according to the present invention using, for example, a DC magnetron sputtering method, thereby reducing a mask blank using a high-quality regenerated substrate. Can be manufactured at cost.

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 (atomic% ratio Mo: Si = 12: 88) of molybdenum (Mo) and silicon (Si) is used as a sputtering target using a single wafer sputtering apparatus. Used in a mixed gas atmosphere of argon (Ar), nitrogen (N ₂ ) and helium (He) (gas pressure 0.3 Pa, gas flow ratio Ar: N ₂ : He = 8: 72: 100) A phase shift film for an ArF excimer laser (wavelength: 193 nm) composed of a single layer mainly composed of molybdenum, silicon, and nitrogen with a thickness of 70 nm is formed by reactive sputtering (DC sputtering) with an electric power of 3.0 kW. Then, a phase shift mask blank was produced. This phase shift film had an transmittance of 4.52% and a phase difference of 182.5 degrees in an ArF excimer laser (wavelength 193 nm).

Next, assuming that there are unacceptable surface defects in the phase shift mask blank produced as described above, the phase shift film of this phase shift mask blank was removed and the substrate was regenerated.
That is, the phase shift mask blank is installed in a chamber, and a mixed gas of ClF ₃ and Ar (flow rate ratio ClF ₃ : Ar = 0.2: 1.8 (SLM)) is introduced into the chamber, and the gas enters the chamber. The phase shift film of the phase shift mask blank was brought into contact with the mixed gas in an unexcited state. At this time, the gas pressure was adjusted to 488 to 502 Torr, the temperature was adjusted to 195 to 202 ° C., and the treatment time was 10 minutes.

  Thus, when the surface of the board | substrate which removed the phase shift film which consists of MoSiN was observed with the electron microscope, generation | occurrence | production of the altered layer, such as the residue of a phase shift film and white turbidity, was not confirmed. Further, the surface reflectance (200 to 700 nm) of the substrate after removing the phase shift film was measured, but there was no change from the substrate before film formation. Further, the surface roughness of the substrate from which the phase shift film was removed was measured with an atomic force microscope (AFM). As a result, Ra = 0.32 nm and Rmax = 6.27 nm. The surface roughness can be easily recovered by re-precise polishing (the final step of the normal polishing process) of the substrate surface, although it was slightly rougher than that (Ra = 0.11nm, Rmax = 1.26nm). I was able to.

That is, according to the method for regenerating a substrate according to the present invention, it was confirmed that the substrate was less damaged after the thin film was removed.
Further, by forming the phase shift film again on the substrate regenerated as described above, a phase shift mask blank using a high quality regenerated substrate can be manufactured.

(Example 2)
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) mixed gas atmosphere (gas pressure 0.1 Pa, gas flow ratio Ar: O ₂ : N ₂ : He = 6: 3: 11: 17) DC power supply By forming a MoSiON film (surface antireflection layer) with a film thickness of 10 nm at a thickness of 3.0 kW, a light shielding film for an ArF excimer laser (wavelength 193 nm) composed of a laminate of a MoSiN film and a MoSiON film is formed. A mask blank was prepared. In addition, the optical density of the light shielding film with respect to ArF excimer laser was 3.0.

Next, assuming that there are unacceptable surface defects in the binary mask blank manufactured as described above, the light shielding film of the binary mask blank was removed, and the substrate was regenerated.
That is, the binary mask blank is installed in the chamber, and a mixed gas of ClF ₃ and Ar (flow rate ratio ClF ₃ : Ar = 0.2: 1.8 (SLM)) is introduced into the chamber, and the gas enters the chamber. The light shielding film of the binary mask blank was brought into contact with the mixed gas in an unexcited state. At this time, the gas pressure was adjusted to 495 to 502 Torr, the temperature was adjusted to 195 to 201 ° C., and the treatment time was 10 minutes.

  When the surface of the substrate from which the light-shielding film composed of the MoSiN film and the MoSiON film was removed in this way was observed with an electron microscope, generation of a residue of the light-shielding film and an altered layer such as white turbidity was not confirmed. Further, the surface reflectance (200 to 700 nm) of the substrate after removing the light shielding film was measured, but there was no change from the substrate before film formation. Further, the surface roughness of the substrate from which the light shielding film was removed was measured by an atomic force microscope (AFM). As a result, Ra = 0.22 nm and Rmax = 3.06 nm. Although it was slightly rough compared to Ra = 0.11nm and Rmax = 1.26nm), the surface roughness can be easily recovered by re-precise polishing (the final stage of the normal polishing process) of the substrate surface. It was.

That is, according to the method for regenerating a substrate according to the present invention, it was confirmed that the substrate was less damaged after the thin film was removed.
Further, by forming the light shielding film again on the substrate regenerated as described above, a binary mask blank using a high-quality regenerated substrate can be manufactured.

(Example 3)
On a translucent substrate made of synthetic quartz glass, a single wafer sputtering apparatus is used, a tantalum (Ta) target is used as a sputtering target, and a mixed gas atmosphere of xenon (Xe) and nitrogen (N ₂ ) (gas pressure 0). 0.076 Pa, gas flow ratio Xe: N ₂ = 71: 29), the power of the DC power source is 1.5 kW, and reactive sputtering (DC sputtering) is used to form a TaN film with a film thickness of 42 nm. Using a Ta target, the power of the DC power source is 2.0 kW in a mixed gas atmosphere of argon (Ar) and oxygen (O ₂ ) (gas pressure 0.3 Pa, gas flow ratio Ar: O ₂ = 58: 32.5). By forming a TaO film with a film thickness of 9 nm, a light shielding film for an ArF excimer laser (wavelength 193 nm) composed of a laminate of a TaN film and a TaO film is formed, and a binary type mask is formed. To prepare a blank. The optical density of the light shielding film with respect to the ArF excimer laser was 3.1.

Next, assuming that there are unacceptable surface defects in the binary mask blank manufactured as described above, the light shielding film of the binary mask blank was removed, and the substrate was regenerated.
That is, the binary mask blank is installed in the chamber, and a mixed gas of ClF ₃ and Ar (flow rate ratio ClF ₃ : Ar = 0.2: 1.8 (SLM)) is introduced into the chamber, and the gas enters the chamber. The light shielding film of the binary mask blank was brought into contact with the mixed gas in an unexcited state. At this time, the gas pressure was adjusted to 496 to 504 Torr, the temperature was adjusted to 198 to 202 ° C., and the treatment time was 10 minutes.

  When the surface of the substrate from which the light-shielding film composed of the TaN film and TaO film was removed in this way was observed with an electron microscope, generation of a residue of the light-shielding film and an altered layer such as white turbidity was not confirmed. Further, the surface reflectance (200 to 700 nm) of the substrate after removing the light shielding film was measured, but there was no change from the substrate before film formation. Further, the surface roughness of the substrate from which the light shielding film was removed was measured by an atomic force microscope (AFM). As a result, Ra = 1.57 nm and Rmax = 21.4 nm. Although it was rough compared to Ra = 0.11 nm and Rmax = 1.26 nm, the surface roughness could be easily recovered by re-precise polishing (the final step of the normal polishing process) of the substrate surface. .

That is, according to the method for regenerating a substrate according to the present invention, it was confirmed that the substrate was less damaged after the thin film was removed.
Further, by forming the light shielding film again on the substrate regenerated as described above, a binary mask blank using a high-quality regenerated substrate can be manufactured.

Example 4
Suitable for EUV light wavelength range of 13 to 14 nm on a substrate (smoothness 0.15 nmRq or less, flatness 50 nm or less) made of SiO ₂ —TiO ₂ glass (thermal expansion coefficient 0.2 · 10 ⁻⁷ / ° C.) A Mo / Si periodic multilayer reflective film was formed. That is, the multilayer reflective film was formed by alternately stacking on the substrate by ion beam sputtering using a Mo target and a Si target. First, a Si film having a thickness of 4.2 nm and a Mo film having a thickness of 2.8 nm were formed, and this was formed as one period. After 40 periods of lamination, a Si film was formed with a thickness of 4.2 nm, and finally a RuNb target was formed as a protective film. A RuNb film was formed to 2.5 nm.
In this way, a substrate with a multilayer reflective film was produced. When the reflectance of this multilayer reflective film was measured with 13.5 nm EUV light at an incident angle of 6.0 degrees, it was 65.9%.

Next, assuming that there are unacceptable surface defects in the substrate with the multilayer reflective film manufactured as described above, the multilayer reflective film of the substrate with the multilayer reflective film is removed and the substrate is regenerated. It was.
That is, the substrate with a multilayer reflective film is installed in a chamber, and a mixed gas of ClF ₃ and Ar (flow rate ratio ClF ₃ : Ar = 0.2: 1.8 (SLM)) is introduced into the chamber, By substituting with the gas, the multilayer reflective film of the substrate with the multilayer reflective film was brought into contact with the mixed gas in an unexcited state. At this time, the gas pressure was adjusted to 495 to 502 Torr, the temperature was adjusted to 195 to 201 ° C., and the treatment time was 10 minutes.

  Observation of the surface of the substrate from which the EUV multilayer reflective film composed of the alternately laminated film of Mo film and Si film was removed with an electron microscope confirmed the occurrence of a multilayer reflective film residue and an altered layer such as cloudiness. Was not. Further, the surface reflectance (200 to 700 nm) of the substrate after removing the multilayer reflective film was measured, but there was no change from the substrate before film formation. Furthermore, as a result of measuring the surface roughness of the substrate from which the multilayer reflective film was removed with an atomic force microscope (AFM), Ra = 1.09 nm and Rmax = 13.8 nm. Although it was rough compared to the thickness (Ra = 0.11nm, Rmax = 1.26nm), the surface roughness can be easily recovered by re-precise polishing (the final stage of the normal polishing process) of the substrate surface. did it.

That is, according to the method for regenerating a substrate according to the present invention, it was confirmed that there was little damage to the substrate after removing the multilayer reflective film of the substrate with the multilayer reflective film.
In addition, by forming the multilayer reflective film again on the substrate regenerated as described above, it is possible to manufacture a substrate with a multilayer reflective film that uses a high-quality recycled substrate.

(Example 5)
First, a multilayer reflective film-coated substrate was produced in the same procedure as in Example 4.
Next, a single-wafer sputtering apparatus is used on the RuNb protective film, and a mixed target of tantalum (Ta) and boron (B) (atomic% ratio Ta: B = 80: 20) is used as the sputtering target. In a mixed gas atmosphere (gas flow ratio Xe: N ₂ = 13: 6) of Xe) and nitrogen (N ₂ ), the power of the DC power source is 1.5 kW, and the TaBN film is formed by reactive sputtering (DC sputtering). A film is formed with a thickness of 50 nm, and subsequently, using the same TaB mixed target, a DC power source in a mixed gas atmosphere (gas flow ratio Ar: O ₂ = 58: 32.5) of argon (Ar) and oxygen (O ₂ ) The reflective mask mask to which EUV exposure light is applied is formed by forming a TaBO film with a film thickness of 15 nm and forming an absorber film composed of a TaBN film and a TaBO film. To prepare a link.

Next, assuming that there are unacceptable surface defects in the reflective mask blank produced as described above, all thin films and multilayer reflective films such as absorber films of the reflective mask blank are removed. The substrate was regenerated.
That is, the reflective mask blank is installed in a chamber, and a mixed gas of ClF ₃ and Ar (flow ratio ClF ₃ : Ar = 0.2: 1.8 (SLM)) is introduced into the chamber, and the gas is introduced into the chamber. The mixed gas in an unexcited state is brought into contact with the surface of the absorber film of the reflective mask blank. At this time, the gas pressure was adjusted to 495 to 502 Torr, the temperature was adjusted to 195 to 201 ° C., and the treatment time was 10 minutes.

  The surface of the substrate from which the absorber film composed of the laminated structure of TaBN and TaBO, the RuNb protective film, and the EUV multilayer reflective film composed of the alternately laminated films of the Mo film and the Si film was completely removed was observed with an electron microscope. In addition, generation of residues such as multilayer reflective films and altered layers such as white turbidity was not confirmed. Moreover, although the surface reflectance (200-700 nm) of the board | substrate after removal was measured, there was no change with the board | substrate before film-forming. Furthermore, as a result of measuring the surface roughness of the removed substrate with an atomic force microscope (AFM), Ra = 1.12 nm and Rmax = 14.3 nm, and the surface roughness of the substrate before peeling (Ra = 0.11 nm, Rmax Although it was rough compared to 1.26 nm), the surface roughness could be easily recovered by re-precise polishing of the substrate surface (the final stage of the normal polishing process).

That is, according to the method for regenerating a substrate according to the present invention, it was confirmed that there was little damage to the substrate after removing the absorber film, the protective film, and the multilayer reflective film of the reflective mask blank.
In addition, by forming the multilayer reflective film, the protective film, and the absorber film again on the substrate reproduced as described above, the EUV exposure light using the high-quality reproduction substrate is applied. A mold mask blank can be manufactured.

(Example 6)
On a translucent substrate made of synthetic quartz glass, using a single wafer sputtering apparatus, an alloy target of tantalum (Ta) and hafnium (Hf) (atomic% ratio Ta: Hf = 80: 20) is used as a sputtering target. Then, a TaHf film (conductive film) with a film thickness of 7 nm is formed by reactive sputtering (DC sputtering) under an argon gas atmosphere (gas pressure of 0.3 Pa) and a DC power supply of 2.0 kW. By using a chromium target and forming a CrN film (Cr: N = 80: 20 atomic% ratio) with a film thickness of 2.5 nm in a mixed gas atmosphere of argon (Ar) and nitrogen (N ₂ ), TaHf A laminated thin film of a film and a CrN film was formed, and a mask blank used for producing an imprint mold was produced.

Next, assuming that there are unacceptable surface defects in the mask blank produced as described above, the laminated thin film of the mask blank was removed, and the substrate was regenerated.
That is, first, a mixed liquid of ceric ammonium nitrate, perchloric acid and pure water was sprayed onto the CrN film surface with a nozzle to remove the CrN film.
Next, a mask blank from which the CrN film has been removed is placed in the chamber, and a mixed gas of ClF ₃ and Ar (flow ratio ClF ₃ : Ar = 0.2: 1.8 (SLM)) is introduced into the chamber. By replacing the inside with the gas, the TaHf film of the mask blank was brought into contact with the non-excited mixed gas. At this time, the gas pressure was adjusted to 495 to 502 Torr, the temperature was adjusted to 195 to 201 ° C., and the treatment time was 10 minutes.

  Thus, when the surface of the board | substrate which removed the laminated thin film of TaHf film | membrane and the CrN film | membrane was observed with the electron microscope, generation | occurrence | production of deteriorated layers, such as the residue of a laminated thin film, and cloudiness, was not confirmed. Further, the surface reflectance (200 to 700 nm) of the substrate after removing the laminated thin film was measured, but there was no change from the initial substrate before film formation. Furthermore, as a result of measuring the surface roughness of the substrate after removing the laminated thin film with an atomic force microscope (AFM), Ra = 1.40 nm and Rmax = 18.0 nm. Although it was rough compared to the thickness (Ra = 0.11nm, Rmax = 1.26nm), the surface roughness can be easily recovered by re-precise polishing (the final stage of the normal polishing process) of the substrate surface. did it.

That is, according to the method for regenerating a substrate according to the present invention, it was confirmed that there was little damage to the substrate after removing the laminated thin film of the mask blank.
Also, a mask blank for producing an imprint mold using a high-quality recycled substrate is manufactured by forming a laminated thin film of the TaHf film and the CrN film on the substrate recycled as described above. can do.

(Comparative Example 1)
The phase shift film of the phase shift mask blank produced in Example 1 was removed by a conventional method to regenerate the substrate.
That is, the phase shift mask blank was immersed in a hydrofluoric acid solution (concentration 0.2%) accommodated in a treatment tank. The temperature of the hydrofluoric acid solution at this time was 40 ° C., and the treatment time was 30 minutes. During the treatment, the mask blank was appropriately swung.

  When the surface of the substrate from which the phase shift film made of MoSiN was removed in this way was observed with an electron microscope, the residue of the phase shift film was not particularly observed, but an altered layer due to white turbidity occurred on the substrate surface. It was confirmed. Further, the surface reflectance (200 to 700 nm) of the substrate after the phase shift film was removed was measured, but the reflectance was generally lowered as compared with the substrate before the film formation due to the influence of the altered layer. Furthermore, as a result of measuring the surface roughness of the substrate after removing the phase shift film with an atomic force microscope (AFM), Ra = 15.1 nm, Rmax = 150 nm, and the surface of the substrate before peeling of the phase shift film Compared to the roughness (Ra = 0.11 nm, Rmax = 1.26 nm), the roughness was very large, and it was confirmed that the substrate damage due to film removal was large. Therefore, in order to recover a good surface roughness by re-polishing the substrate surface, it is necessary to re-polish from the first stage of the normal substrate polishing process before film formation, and the re-polishing process load is increased. growing.

DESCRIPTION OF SYMBOLS 10 Chamber 11 Process substrate 12 Stages 13 and 14 Gas filling containers 15 and 16 Flow rate controller 17 Injection nozzle 18 Exhaust pipe 19 Exhaust gas processing apparatus

Claims (17)

A method of regenerating a substrate by removing the thin film of a mask blank provided with a thin film for pattern formation on a main surface of a substrate made of glass or a transfer mask produced using the mask blank,
The thin film of the mask blank or the transfer mask contains a compound of any element of chlorine (Cl), bromine (Br), iodine (I), and xenon (Xe) and fluorine (F). A method for regenerating a substrate, wherein the substrate is removed by contact with a non-excited substance.   The method for regenerating a substrate according to claim 1, wherein the thin film is formed of a single layer or a plurality of layers, and at least a layer in contact with the substrate is formed of a material that can be dry-etched with a fluorine-based gas.   The layer in contact with the substrate is formed of any one of a material containing silicon (Si), a material containing metal and silicon (Si), and a material containing tantalum (Ta). The method for regenerating a substrate according to claim 2.   4. The method for regenerating a substrate according to claim 1, wherein the substrate is made of synthetic quartz glass.   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 1. A method for regenerating a substrate by removing the multilayer reflective film of a substrate with a multilayer reflective film comprising a multilayer reflective film having a structure in which a low refractive index layer and a high refractive index layer are alternately laminated on a main surface of a substrate made of glass Because
The multilayer reflective film of the substrate with the multilayer reflective film includes a compound of any element of chlorine (Cl), bromine (Br), iodine (I), and xenon (Xe) and fluorine (F). A method for regenerating a substrate, wherein the substrate is removed by contact with a non-excited substance.   7. The method for regenerating a substrate according to claim 6, wherein the low refractive index layer is made of silicon (Si) and is in contact with the main surface of the substrate. The method for regenerating a substrate according to claim 6 or 7, wherein the substrate is made of SiO ₂ -TiO ₂ -based low thermal expansion glass.   A multilayer reflective film having a structure in which a low refractive index layer and a high refractive index layer are alternately laminated is formed on a substrate regenerated by the method for regenerating a substrate according to claim 6. A method for manufacturing a substrate with a multilayer reflective film. A reflective mask blank comprising a multilayer reflective film having a structure in which a low refractive index layer and a high refractive index layer are alternately laminated on a main surface of a glass substrate, and an absorber film for pattern formation, or the reflection A method of regenerating a substrate by removing the multilayer reflective film of a reflective mask produced using a mold mask blank,
The reflective mask blank or the multilayer reflective film of the reflective mask is coated with any element of chlorine (Cl), bromine (Br), iodine (I), and xenon (Xe) and fluorine (F). A method for regenerating a substrate, wherein the substrate is removed by contact with a non-excited substance containing the compound.   11. The method for regenerating a substrate according to claim 10, wherein the low refractive index layer is made of silicon (Si) and is in contact with the main surface of the substrate. The method for regenerating a substrate according to claim 10 or 11, wherein the substrate is made of SiO ₂ -TiO ₂ -based low thermal expansion glass.   A multilayer reflective film having a structure in which a low refractive index layer and a high refractive index layer are alternately laminated on a substrate regenerated by the method for regenerating a substrate according to any one of claims 10 to 12, and an absorption for pattern formation A manufacturing method of a reflective mask blank, comprising forming a body film in order. In a mask blank having a thin film for pattern formation on the main surface of a substrate made of glass, the thin film of the mask blank corresponding to a method for producing an imprint mold in which the thin film and the substrate are etched by dry etching is removed. And reclaiming the substrate,
The thin film of the mask blank is a non-excited substance containing a compound of any element of chlorine (Cl), bromine (Br), iodine (I), and xenon (Xe) and fluorine (F) A method for regenerating a substrate, wherein the substrate is removed by contacting the substrate.   15. The method for regenerating a substrate according to claim 14, wherein the thin film is formed of a single layer or a plurality of layers, and at least a layer in contact with the substrate is formed of a material mainly composed of tantalum (Ta). .   The method for regenerating a substrate according to claim 14 or 15, wherein the substrate is made of synthetic quartz glass.   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 14.

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