JP6444680B2 - Manufacturing method of substrate, manufacturing method of substrate with multilayer reflective film, manufacturing method of mask blank, and manufacturing method of transfer mask - Google Patents

Description

  The present invention relates to a method for manufacturing a substrate, a method for manufacturing a mask blank substrate, a method for manufacturing a substrate with a multilayer reflective film using the mask blank substrate, and a mask blank using the mask blank substrate or the substrate with a multilayer reflective film. And a transfer mask manufacturing method using the mask blank.

  In recent years, in semiconductor devices, the density and accuracy of highly integrated circuits have been further increased. As a result, there is a demand for flattening, smoothing, and reducing defects at a finer size for mask blank substrates and transfer masks used for circuit pattern transfer.

  For example, as a mask blank used in the semiconductor design rule 1xnm generation and later (half pitch (hp) 14 nm, 10 nm, 7 nm, etc.), a reflective mask blank for EUV exposure, a binary mask blank for ArF excimer laser exposure, and a phase shift There are mask blanks and mask blanks for nanoimprints, but in the mask blanks used in these generations, defects of 30 nm class (SEVD (Sphere Equivalent Volume Diameter) of 21.5 nm or more and 34 nm or less) or more Even small size defects can be a problem. For this reason, it is preferable that the main surface of the substrate used for the mask blank (that is, the surface on the side where the transfer pattern is formed) has as few as possible 30 nm-class defects. Further, in a high-sensitivity defect inspection apparatus that performs defect inspection of 30 nm-class defects, the surface roughness affects background noise. That is, if the smoothness is insufficient, a large number of pseudo defects due to surface roughness are detected, and defect inspection cannot be performed. For this reason, the main surface of the substrate used for the mask blank used after the 1 × nm generation of semiconductor design rules is required to have a smoothness of not more than 0.08 nm in terms of root mean square roughness (RMS).

  Further, in recent years, in the hard disk drive (HDD), the flying height of the recording / reading head with respect to the magnetic recording medium is further reduced as the recording capacity of the magnetic recording medium is increased. It has become. As such a head, a head mounted with a DFH (Dynamic Flying Height) mechanism is also widespread. The DFH mechanism operates so that the magnetic head thermally expands due to the heat generated by the heating element provided in the magnetic head, and the magnetic head projects slightly in the direction of the air bearing surface, thereby keeping the flying height constant. Can do. A head equipped with such a DFH mechanism has a flying height of about several nanometers, and thus a defect such as a head crash tends to occur when a magnetic recording medium is used. In order to reduce such defects, the surface of the magnetic recording medium substrate is required to have a low defect surface with high smoothness and substantially no protrusions.

  As a substrate for a magnetic recording medium, there is a metal substrate such as aluminum, but a glass substrate that is less likely to be plastically deformed than a metal substrate and that provides high surface smoothness when the main surface of the substrate is mirror-polished is preferably used. It has been.

  Various processing methods have been proposed so far in order to make the main surface of the mask blank substrate and the magnetic recording medium substrate have a high smoothness, a low defect, and substantially no protrusions. It has been difficult to realize a substrate having a main surface that satisfies the above characteristics.

  2. Description of the Related Art In recent years, a processing method using catalyst-based etching (hereinafter also referred to as “CARE”) has been proposed as a processing method for a substrate that requires a low defect and high smoothness with substantially no protrusions on the main surface. In catalyst-based etching (CARE) processing, a hydroxyl group is generated as an active species from a molecule in a processing fluid adsorbed on a processing reference surface formed from a catalyst substance, and the active species approaches or contacts the processing reference surface. It is considered that the fine convex portions on the surface undergo a hydrolysis reaction and the fine convex portions are selectively removed. Patent Document 1 describes a processing method by catalyst-based etching using a metal catalyst.

In Patent Document 1, in the presence of water such as pure water or ultrapure water used as a processing fluid, the processing reference surface of the catalytic material is brought into contact with or close to the surface of the workpiece made of a solid oxide such as glass, A solid oxide processing method is described in which a processing reference surface and a workpiece surface are moved relative to each other, a decomposition product due to hydrolysis is removed from the workpiece surface, and the workpiece surface is processed. The solid oxide processing method is also referred to as a CARE processing method). As the catalyst material, a material containing a metal element and having an electron d orbit near the Fermi level is used. Specific metal elements include, for example, platinum (Pt), gold (Au), silver ( Ag), copper (Cu), nickel (Ni), chromium (Cr), and molybdenum (Mo). It is described that the catalyst material does not need to be bulk, and may be a thin film in which a metal or a transition metal is formed by sputtering or the like on the surface of a base material that is inexpensive and has good shape stability. In addition, the base material for forming the catalyst material on the surface may be a hard elastic material, and for example, it is described that fluorine rubber can be used.
Patent Document 1 describes that the pH of the processing fluid is preferably adjusted in the range of 2 to 12, and that the adjustment to the alkaline region is performed by adding KOH (Patent Document 1). Paragraphs 0031 and 0056).

International Publication No. 2013/084934

In the CARE processing method, the load applied to the substrate (hereinafter also referred to as processing pressure) with the processing fluid interposed between the substrate to be processed and the catalyst depends on the use of the substrate, that is, the substrate A relatively wide range can be set according to the number of defects and smoothness allowed on the main surface. For example, in applications such as a reflective mask blank for EUV exposure, it is necessary to use a substrate having a low defect and a high smooth main surface.
From the viewpoint of whether or not the conventional CARE processing method can be applied to the production of a substrate having such a low-defect and high-smooth main surface, the present inventor When properties such as surface roughness of a substrate processed using water such as water or an inorganic alkaline aqueous solution such as KOH as a processing fluid were examined, the following problems were found.

  First, when the defect inspection of the main surface of the processed substrate obtained using water such as pure water as the processing fluid is performed, a minute defect that can be observed only with a high-sensitivity defect inspection apparatus. There was a case where a leak flaw occurred. This is because a water film made of pure water or the like interposed between the substrate to be processed and the catalyst is thinned by applying a processing pressure in CARE processing, but a relatively high processing pressure of, for example, 100 hPa or more is applied. Then, pure water escapes from between the substrate and the catalyst, and the thinned water film may be partially interrupted, resulting in a drainage phenomenon. In the portion where the drainage occurs, the substrate and the catalyst As a result of relative movement of the substrate and the catalyst with no water film interposed between them, it is considered that a micro-sleek flaw occurred on the main surface of the substrate.

Next, when the CARE process is performed using an inorganic alkaline aqueous solution such as KOH or NaOH as a processing fluid, a water drain phenomenon is unlikely to occur. This is because the viscosity of an inorganic alkaline aqueous solution such as KOH or NaOH is higher than that of pure water or the like described above, so even if a processing pressure that causes a drainage phenomenon in the case of water such as pure water is applied, It is considered that the inorganic alkali aqueous solution having a high viscosity is difficult to escape from between the substrate and the catalyst.
In general, when a substrate made of a material containing a silicon oxide is CARE processed, orthosilicate (H ₄ SiO ₄ ), metasilicic acid (H ₂ SiO ₃ ), metadisilicate (H ₂ SiO ₂ ), etc. It is known that silicic acid is produced. Since such a silicic acid is similar in composition to the material of the substrate, it is very difficult to remove the silicic acid remaining on the substrate without affecting the surrounding substrate surface. Such orthosilicic acid or the like is dissolved in an inorganic alkaline aqueous solution such as KOH or NaOH, so that orthosilicic acid or the like can be removed.
However, it has been confirmed that when an inorganic alkaline aqueous solution such as KOH or NaOH is used, the roughness of the main surface of the substrate after processing is deteriorated and a minute convex defect is detected. This is because Na ⁺ ions and K ⁺ ions contained in an inorganic alkaline aqueous solution such as KOH and NaOH are combined with silicate ions to form a silicate. It is thought that it remained and was detected as a minute convex defect.
Thus, in the conventional CARE processing method, as described above, there is a possibility that micro-sleeve scratches and micro-surface roughness that can become concave defects are generated, and furthermore, micro-convex defects may remain. There is a disadvantage in application to applications that require the use of a substrate having a low-defect and high-smooth main surface, such as a reflective mask blank for use.

  The present invention has been made to solve the above-described problems, and a method for manufacturing a substrate capable of manufacturing a substrate having a main surface with low defects and a high smoothness, and a method for manufacturing a substrate with a multilayer reflective film An object of the present invention is to provide a mask blank manufacturing method and a transfer mask manufacturing method.

  In order to solve the above-described problems, the present invention has the following configuration.

(Configuration 1)
A substrate preparation step of preparing a substrate having a main surface made of a material containing an oxide;
The processing reference surface of the catalytic substance and the main surface are brought into contact with or close to each other, and the main surface and the processing reference surface are moved relative to each other while a processing fluid is interposed between the processing reference surface and the main surface. In the method of manufacturing a substrate, the step of performing a catalyst-based etching of the main surface by
The method of manufacturing a substrate, wherein the processing fluid includes an organic alkaline aqueous solution.

(Configuration 2)
The organic alkali aqueous solution is an aqueous solution containing at least one of tetramethylammonium hydroxide (TMAH), tetraethylammonium hydroxide (TEAH), and tetrabutylammonium hydroxide (TBAH). The manufacturing method of the board | substrate of description.

(Configuration 3)
3. The method for manufacturing a substrate according to Configuration 1 or 2, wherein the substrate is made of a material containing at least the main surface including silicon oxide.

(Configuration 4)
4. The method for manufacturing a substrate according to any one of configurations 1 to 3, wherein the processing reference surface has a porous surface, and the porous surface is formed of the catalyst substance.

(Configuration 5)
The method for manufacturing a substrate according to Configuration 4, wherein a load of 50 hPa or more is applied to the substrate.

(Configuration 6)
6. The method of manufacturing a substrate according to any one of configurations 1 to 5, wherein the substrate is a mask blank substrate.

(Configuration 7)
A method for producing a substrate with a multilayer reflective film, comprising: forming a multilayer reflective film on a main surface of the substrate obtained by the method for producing a substrate according to Configuration 6.

(Configuration 8)
On the main surface of the substrate obtained by the method for producing a substrate according to Configuration 6, or on the multilayer reflective film of the substrate with a multilayer reflective film obtained by the method for producing a substrate with a multilayer reflective film according to Configuration 7, A method of manufacturing a mask blank, comprising forming a transfer pattern thin film.

(Configuration 9)
A method for producing a transfer mask, comprising: patterning a thin film for transfer pattern of a mask blank obtained by the method for producing a mask blank according to Configuration 8, to form a transfer pattern.

  According to the substrate manufacturing method of the present invention, when processing by catalyst-based etching, an organic alkaline aqueous solution is used as a processing fluid interposed between the substrate to be processed and the processing reference surface of the catalyst material. Even when a relatively high load (processing pressure) is applied, the occurrence of water breakage can be suppressed, so that a processing fluid is always interposed between the substrate and the processing reference surface during relative movement between the substrate and the processing reference surface. In addition, it is possible to suppress the formation of silicate, thereby suppressing micro-sleek scratches, micro-surface roughness, and micro-convex defects that can be concave defects on the main surface of the substrate. For this reason, it is possible to provide a substrate having a low-defect and high-smooth main surface.

  In addition, according to the method for manufacturing a substrate with a multilayer reflective film according to the present invention, a substrate with a multilayer reflective film is manufactured using the substrate obtained by the above-described substrate manufacturing method. And a substrate with a multilayer reflective film having desired characteristics can be manufactured.

  Further, according to the mask blank manufacturing method of the present invention, the mask is obtained using the substrate obtained by the above-described substrate manufacturing method or the substrate with the multilayer reflective film obtained by the above-described method of manufacturing the substrate with the multilayer reflective film. Since the blank is manufactured, a mask blank having desired characteristics can be manufactured while maintaining a highly smooth surface state with low defects.

  In addition, according to the method for manufacturing a transfer mask according to the present invention, a transfer mask is manufactured using the mask blank obtained by the above-described mask blank manufacturing method, so that a high-smooth surface state with low defects is maintained. Thus, a transfer mask having desired characteristics can be manufactured.

It is a fragmentary sectional view showing composition of a substrate processing device which performs local processing by catalyst standard etching to a mask blank substrate. It is a top view which shows the structure of the board | substrate processing apparatus shown in FIG. It is sectional drawing which showed typically the principal part of the process reference plane of the catalyst surface plate of the board | substrate processing apparatus shown in FIG.1 and FIG.2. The result of the test which compared the surface roughness of the main surface of the said board | substrate by the difference in immersion aqueous solution about the board | substrate immersed in inorganic alkaline aqueous solution (NaOH, KOH) and organic alkaline aqueous solution (TMAH: tetramethylammonium hydroxide). It is a graph shown relatively. It is a table | surface which shows the content of each processing condition about Examples 1-5 and Comparative Examples 1 and 2, and the evaluation before and behind processing.

  Hereinafter, a method for manufacturing a substrate according to an embodiment of the present invention, a method for manufacturing a substrate with a multilayer reflective film using the substrate, a method for manufacturing a mask blank using the substrate or the substrate with a multilayer reflective film, and the mask blank A method of manufacturing a transfer mask using the above will be described in detail with reference to timely drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals, and the description thereof may be simplified or omitted.

Embodiment 1 FIG.
In Embodiment 1, a substrate manufacturing method and a substrate processing apparatus will be described.

In the first embodiment, a substrate preparation step of preparing a substrate having a main surface made of a material containing an oxide, a processing reference surface of the catalytic substance and a main surface of the substrate are brought into contact with or approached, and the processing reference surface and the main surface A substrate is manufactured by a substrate processing step in which the main surface of the substrate is processed by catalyst-based etching with a processing fluid interposed therebetween.
Hereinafter, each process will be described in detail.

1. Substrate Preparation Step In the substrate manufacturing method, first, a substrate having a main surface made of a material containing an oxide is prepared.

The substrate to be prepared is, for example, a substrate made of a material containing an oxide as a whole, a substrate in which a thin film made of a material containing an oxide is formed on an upper surface used as a main surface, or both an upper surface and a lower surface used as a main surface A substrate on which a thin film made of a material containing an oxide is formed.
The substrate on which the thin film is formed may be a substrate in which a thin film made of a material containing oxide is formed on an upper surface or a lower surface used as a main surface of a substrate body made of a material containing oxide. The board | substrate with which the thin film which consists of a material containing an oxide was formed in the upper surface used as a main surface of the board | substrate main body which consists of materials other than the lower surface, and a lower surface may be sufficient.

Examples of the material of the substrate and the substrate body made of a material containing an oxide include glass such as synthetic quartz glass, soda lime glass, borosilicate glass, aluminosilicate glass, SiO ₂ —TiO ₂ glass, and glass ceramics. . Moreover, silicon, carbon, and a metal are mentioned as a material of the board | substrate body which consists of other than the material containing an oxide.
Examples of the oxide that forms the thin film include silicon oxide, metal oxide, and alloy oxide. Specifically, as the silicon oxide, silicon oxide (SiO _x , (x> 0)), metal silicide oxide containing metal and silicon (Me _x Si _y O _z , Me: metal, x> 0) , Y> 0, and z> 0). Examples of the metal oxide include tantalum oxide (TaO _x , (x> 0)) and ruthenium oxide (RuO _x (x> 0)). As the alloy oxide, tantalum boron oxide _{(Ta x B y Oz, (} x> 0, y> 0, and z> 0)), tantalum hafnium oxide _{(Ta x Hf y O z,} (x> 0, y> 0, z> 0), tantalum chromium oxide _{(Ta x Cr y O z,} (x> 0, y> 0, and z> 0)) and the like. materials containing such oxides The thin film made of can be formed, for example, by vapor deposition, sputtering, or electroplating.
In addition, the above-described oxide may contain elements such as nitrogen, carbon, hydrogen, fluorine and the like without departing from the effects of the present invention.
The substrate to be prepared is preferably made of a silicon substrate (SiO _x (x> 0) on the upper surface and the lower surface, which are the main surfaces of the glass substrate main body and the main surface of the glass substrate main body, which is difficult to plastically deform and easily obtain a high smoothness main surface. )).

The substrate to be prepared may be a mask blank substrate or a magnetic recording medium substrate. The mask blank substrate may be used for manufacturing any of a reflective mask blank, a binary mask blank, a phase shift mask blank, and a nanoimprint mask blank. In the binary mask blank, the material of the light shielding film may be any of MoSi, Ta, and Cr. The phase shift mask blank may be any of a halftone type phase shift mask blank, a Levenson type phase shift mask blank, and a chromeless type phase shift mask blank. The substrate material used for the reflective mask blank needs to be a material having low thermal expansion. For this reason, the substrate material used for the reflective mask blank for EUV (Extreme Ultra Violet) exposure is preferably, for example, SiO ₂ —TiO ₂ glass. Further, the substrate material used for the transmissive mask blank needs to be a material having translucency with respect to the exposure wavelength to be used. For this reason, as a substrate material used for the binary mask blank and the phase shift mask blank for ArF excimer laser exposure, for example, synthetic quartz glass is preferable. In addition, the substrate material used for the magnetic recording medium substrate needs to be chemically strengthened after the polishing step in order to improve impact resistance, strength and rigidity. For this reason, the substrate material used for the magnetic disk substrate is preferably, for example, a multicomponent glass such as borosilicate glass or aluminosilicate glass.

  The substrate to be prepared is preferably a substrate whose main surface has been polished using fixed abrasive grains, loose abrasive grains, or the like. For example, the upper and lower surfaces used as the main surface are polished using the following processing method so as to have predetermined smoothness and flatness. Even when the lower surface is not used as the main surface, the lower surface is also polished using the following processing method as necessary so as to have predetermined smoothness and flatness. However, it is not necessary to perform all the following processing methods, and it is performed by selecting appropriately so as to have predetermined smoothness and flatness.

As a processing method for reducing the surface roughness, for example, there are polishing and lapping using abrasive grains such as cerium oxide and colloidal silica.
As processing methods for improving the flatness, for example, magneto-rheological fluid polishing (MRF), local chemical mechanical polishing (LCMP), gas cluster ion beam etching (Gas Cluster Ion Beam Etching). : GCIB), and dry chemical planarization (DCP) using local plasma etching.

MRF is a local processing method in which a magnetic polishing slurry obtained by mixing a polishing slurry in a magnetic fluid is brought into contact with a workpiece at high speed and polishing is performed locally by controlling the residence time of the contact portion.
In LCMP, a polishing slurry containing abrasive grains such as a small-diameter polishing pad and colloidal silica is used. By controlling the residence time of the contact portion between the small-diameter polishing pad and the workpiece, the surface of the workpiece is mainly projected. This is a local processing method for polishing a portion.
GCIB is a gas produced by ejecting a gas reactive substance (source gas) at normal temperature and pressure while adiabatically expanding into a vacuum apparatus to generate a gas cluster, and irradiating it with an electron beam to ionize it. This is a local processing method in which cluster ions are accelerated by a high electric field to form a gas cluster ion beam, which is irradiated to a workpiece to be etched.

DCP is a local processing method in which dry etching is locally performed by locally performing plasma etching and controlling the amount of plasma etching according to the degree of convexity.
In order to improve the surface roughness damaged by the above-described processing method for improving the flatness, as a processing method for improving the surface roughness while maintaining the flatness as much as possible, for example, float polishing, EEM (Elastic) Emission Machining) and hydroplane polishing.

  In order to shorten the processing time by catalyst-based etching, it is preferable that the main surface of the substrate to be prepared has a root mean square roughness (RMS) of 0.3 nm or less, more preferably 0.15 nm or less.

2. Substrate processing step Next, the processing reference surface of the catalytic substance and the main surface of the substrate are brought into contact with or close to each other, and the processing reference surface and the main surface are relatively opposed with the processing fluid interposed between the processing reference surface and the main surface. The main surface is processed by catalytic reference etching (CARE) by moving.
When both the upper surface and the lower surface of the substrate are used as the main surface, the lower surface CARE processing may be performed after the upper surface CARE processing, or the upper surface CARE processing may be performed after the lower surface CARE processing. CARE processing on both sides of the lower surface may be performed simultaneously. Even if the lower surface is not used as the main surface, the lower surface is also processed by catalyst-based etching as necessary. When CARE processing is also performed on the lower surface that is not used as the main surface, the upper surface used as the main surface is required to have high quality in terms of defect quality. It is preferable to perform processing.

In this case, first, the main surface of the substrate is disposed so as to face the processing reference surface made of the catalyst material. Then, the processing fluid is supplied between the processing reference surface and the main surface, and the main surface of the substrate is brought into contact with or close to the processing reference surface with the processing fluid interposed between the processing reference surface and the main surface. The processing reference surface and the main surface are relatively moved while applying a predetermined load (processing pressure) to the substrate. When the processing reference surface and the main surface are moved relative to each other with the processing fluid interposed between the processing reference surface and the main surface, the activity generated from the molecules in the processing fluid adsorbed on the processing reference surface The seed and the main surface react and the main surface is processed. Here, this reaction is a hydrolysis reaction when the substrate surface contains an oxide or an oxide. The active species are generated only on the processing reference surface and deactivated when they are separated from the vicinity of the processing reference surface. Therefore, there is almost no reaction with the active species other than the main surface with which the processing reference surface contacts or approaches. In this way, the main surface is processed by catalyst-based etching. In the processing based on the catalyst-based etching, since no abrasive is used, damage to the mask blank substrate M is extremely small, and generation of new defects can be prevented.
Note that the contact or approach between the processing reference surface and the main surface occurs on the processing reference surface in a state where a processing fluid is interposed between both surfaces during relative movement of both surfaces in the CARE processing. It refers to the distance relationship between the two surfaces that is set to allow the hydrolysis reaction to reach the main surface.

The relative motion between the processing reference surface and the main surface is not particularly limited as long as the processing reference surface and the main surface move relative to each other. When the substrate is fixed and the processing reference surface is moved, the processing reference surface is fixed and the substrate is moved, or both the processing reference surface and the substrate are moved. When the processing reference plane moves, the movement may be a case where the machining reference plane rotates around an axis in a direction perpendicular to the main surface of the substrate or a case where the processing reference plane reciprocates in a direction parallel to the main surface of the substrate. Similarly, when the substrate moves, the movement may be when the substrate rotates about an axis perpendicular to the main surface of the substrate or when the substrate reciprocates in a direction parallel to the main surface of the substrate.
The load (processing pressure) applied to the substrate is, for example, 5 hPa to 350 hPa, and preferably 50 hPa to 250 hPa. For example, when the processing pressure is 100 hPa or higher and the processing pressure is relatively high, it becomes easier to apply the processing pressure to the main surface more uniformly than when the processing pressure is relatively low. A processing standard that makes it easier to reduce the thickness of a liquid film composed of an intervening processing fluid (organic alkaline aqueous solution), suppresses the entry of minute foreign objects between the processing reference surface and the main surface, and moves relatively. Since the fluctuation of the rotational movement of the surface and the main surface can be suppressed, the number of concave / convex defects on the main surface can be reduced. Further, when the processing pressure is relatively high, it becomes easy to apply the processing pressure uniformly to the main surface, so that a predetermined processing allowance described later can be made uniform over the entire main surface.
The machining allowance in the process by the catalyst reference etching is, for example, 5 nm to 100 nm. When there is a protrusion protruding from the main surface on the main surface of the substrate, the machining allowance is preferably set to a value larger than the height of the protrusion. By setting the machining allowance to a value larger than the height of the protrusion, the protrusion can be removed by CARE processing.

  The catalyst substance that forms the processing reference surface may be any material that generates active species that hydrolyze the substrate surface with respect to the processing fluid, and a material containing a metal element, preferably a transition metal element, is preferable. For example, at least one metal of elements belonging to Group 4, Group 6, Group 8, Group 9, Group 10, Group 11 and Group 11 of the periodic table and alloys containing them are preferably used. Specifically, platinum (Pt), titanium (Ti), zirconium (Zr), hafnium (Hf), vanadium (V), niobium (Nb), tantalum (Ta), chromium (Cr), molybdenum (Mo), At least one metal of tungsten (W), iron (Fe), ruthenium (Ru), copper (Cu), and osmium (Os), an alloy containing them, and oxygen (O), nitrogen (N ) And an alloy compound containing at least one component of carbon (C). Examples of the alloy compound described above include oxides, nitrides, carbides, oxynitrides, oxycarbides, nitride carbides, and oxynitride carbides of the above-described alloys. When such an alloy or alloy compound is used, the mechanical durability and chemical stability of the processing reference surface can be improved.

  The catalyst material layer containing the catalyst material is formed on a porous pad. This porous pad, including its effects, will be described in detail at the substrate surface creation means described later.

Area of the working reference plane is greater than the area of the main surface of the substrate, for ^example, a 100mm ² ~10000mm 2. In this case, since the entire main surface of the substrate can be processed to face the processing reference surface, the processing time can be shortened, and the occurrence of defects such as scratches due to the edge of the processing reference surface can be suppressed.
Further, the area of the processing reference plane may be smaller than the area of the main surface of the substrate. In this case, by reducing the processing reference surface, the substrate processing apparatus can be reduced in size, and high-precision processing can be performed reliably.

The processing fluid shows little solubility in a normal state with respect to the substrate, and includes an organic alkaline aqueous solution that induces a hydrolysis reaction. This is a feature of the present invention. By using such a processing fluid, the substrate is not dissolved by the processing fluid, and unnecessary deformation of the substrate can be prevented. As the organic alkaline aqueous solution, for example, each of tetramethylammonium hydroxide (TMAH), tetraethylammonium hydroxide (TEAH), and tetrabutylammonium hydroxide (TBAH) may be used alone or in an appropriate mixture. Can do. As the medium of the processing fluid, an aqueous medium such as water, deionized water, pure water, or ultrapure water can be used. The pH of the treatment fluid is preferably pH 9 to pH 13 and more preferably pH 10 to pH 11 in the alkaline region. The temperature when the processing fluid is used is preferably set in a range of 10 ° C. to 80 ° C. within a range in which the substrate is not deformed in consideration of a change in viscosity of the processing fluid.
In addition, when the substrate is not normally dissolved by a solution in which halogen-containing molecules are dissolved, and does not inhibit the hydrolysis reaction induced by a processing fluid containing an organic alkaline aqueous solution, the substrate is solidified by crystallization or the like. In the case where it does not have the property of remaining on and difficult to be removed, the treatment fluid may include a solution in which molecules containing halogen are dissolved. In addition, a processing fluid containing an organic alkaline aqueous solution is treated with Na ⁺ ions or K ⁺ ions that generate silicates that can become minute foreign matters (convex defects) on the substrate in the presence of silicate ions derived from the substrate. It is basically impossible to include an inorganic alkaline aqueous solution or substance such as NaOH or KOH supplied in the fluid. However, an inorganic alkaline aqueous solution such as NaOH or KOH may be included as long as the amount of silicate formed does not matter and does not deteriorate the roughness of the substrate surface.

When at least the main surface of the substrate is made of a material containing silicon oxide, the above-mentioned catalyst substance is used, and an organic alkaline aqueous solution is used as a processing fluid, so that even if processing by catalyst-based etching is performed, the conventional inorganic Because it does not contain Na ⁺ ions or K ⁺ ions contained in the alkaline aqueous solution, silicates are not generated in the presence of silicate ions, and fine foreign substances consisting of the silicates remain on the substrate. Therefore, the occurrence of minute convex defects on the main surface of the substrate can be suppressed.

  1 and 2 show an example of a substrate processing apparatus that performs processing by catalyst-based etching on the main surface of the substrate. FIG. 1 is a partial cross-sectional view of the substrate processing apparatus, and FIG. 2 is a plan view of the substrate processing apparatus. In the following, the case where the lower surface M1 used as the main surface of the substrate M is CARE processed using the substrate processing apparatus shown in FIGS. 1 and 2 will be described. However, when the upper surface M2 of the substrate M is also used as the main surface. Replaces the lower surface M1 and the upper surface M2, and the upper surface M2 is also CARE processed. Even when the upper surface M2 is not used as the main surface, the upper surface M2 is also CARE processed as necessary. In that case, CARE processing of the lower surface M1 is performed after CARE processing of the upper surface M2.

  The substrate processing apparatus 1 includes a substrate support means 2 for supporting a substrate M having a main surface made of an oxide-containing material, a substrate surface creation means 3 having a processing reference surface 33 for a catalytic substance, a processing reference surface 33 and a main processing surface. The main surface of the substrate M contacts or approaches the processing reference surface 33 in a state where the processing fluid is interposed between the processing fluid supply means 4 for supplying the processing fluid between the surface and the processing reference surface 33 and the main surface. Drive means 5, a cylindrical chamber 6 that accommodates the substrate surface creation means 3, and a relative motion means 7 that relatively moves the processing reference surface 33 and the main surface of the substrate M.

  The substrate support means 2 rotates the head rod 20 that is rotationally driven by the relative motion means 7 that will be described in detail later, and the substrate M that is attached to the lower end of the head rod 20 and that has the lower surface M1 facing downward. A columnar head portion 21 that can be supported, and a substantially disc-shaped vacuum chuck portion 22 that is detachably attached to the lower portion of the head portion 21 and that attracts and holds the upper surface M2 of the substrate M are provided. . The head portion 21 can be rotated on a horizontal plane in the chamber 6 by rotating the head rod 20 by the relative motion means 7 described in detail later (see a double-headed arrow B in FIGS. 1 and 2). The vacuum chuck portion 22 is schematically constituted by a concave portion (not shown) having a circular cross section formed on the lower surface of the head portion 21 and its peripheral portion (not shown). On the bottom surface of the recess (not shown) of the vacuum chuck portion 22, tips (not shown) of a plurality of branch pipes (not shown) of the vacuum pipe 23 extending from an external vacuum device (not shown) are provided. Is open. Each open end (not shown) of the plurality of branch pipes (not shown) is arranged at a position radially arranged from the center of the recess (not shown) of the vacuum chuck portion 22, for example. It is not limited. Here, when the vacuum apparatus (not shown) is operated in a state where the upper surface M2 of the substrate M is in contact with the peripheral part (not shown) of the vacuum chuck part 22, the concave part (not shown) of the vacuum chuck part 22 is shown. Z) and the substrate M is depressurized, and the substrate M can be fixed by the suction force generated by the depressurization.

  In the head portion 21, an air introduction space (not shown) is formed above the vacuum chuck portion 22, and the air introduction space (not shown) is inserted into the air introduction space (not shown) via an air tube (not shown). Air is configured to be supplied. Air is supplied into an air introduction space (not shown) in a state where a processing fluid is interposed between the lower surface M1 of the substrate M adsorbed and held by the vacuum chuck portion 22 and the processing reference surface 33 of the catalyst surface plate 31. When the pressure is applied, the head unit 21 presses the vacuum chuck unit 22 downward, so that a load (processing) is applied to the substrate M sucked and held by the vacuum chuck unit 22 via the vacuum chuck unit 22. Pressure) is applied. For this reason, the air introduction space (not shown) functions as an air cylinder that applies a load (processing pressure) to the substrate M. In the head portion 21, a load applied to the substrate M is measured by an air introduction space (not shown), and an air valve (not shown) is turned on / off so as not to exceed a predetermined load (processing pressure). A load cell (not shown) for controlling a load (processing pressure) applied to the substrate M by an air introduction space (not shown) is provided. These air introduction space (not shown), air valve (not shown), and load cell (not shown) control the load (processing pressure) applied to the substrate M when processing the substrate M by catalyst-based etching. The load control means (not shown) is configured.

  The substrate support means 2 is disposed at an upper position in the chamber 6, and the substrate surface creation means 3 is disposed in the chamber 6. The chamber 6 is supplied from the processing fluid supply means 4 and the opening 61 formed in the center of the bottom 63 of the chamber 6 in order to arrange the shaft portion 71 of the relative motion means 7 described in detail later in the chamber 6. In order to discharge the treated fluid, a discharge port 62 formed on the bottom 63 of the chamber 6 closer to the outer periphery than the opening 61 is provided. In FIG. 1, the state in which the processing fluid is discharged from the discharge port 62 is indicated by an arrow.

  The substrate surface creation means 3 includes a catalyst surface plate 31. The catalyst surface plate 31 is attached to a catalyst surface plate mounting portion (not shown) provided in the shaft portion 71 of the relative motion means 7. The catalyst surface plate 31 includes a surface plate body 32 whose surface faces upward, a base material formed on the entire surface of the surface plate body 32 so as to cover the surface plate body 32, and a process in which a catalyst is attached to the surface. And a reference surface 33. The catalyst material on the processing reference surface 33 opposes the lower surface M1 of the substrate M supported by the substrate support means 2 above it.

  The processing reference surface 33 has a porous structure in which a catalytic substance is deposited on a porous base material (porous base material). This structure will be described with reference to FIG. As shown in the figure, the processing reference surface 33 is formed by depositing the catalyst material layer 102 along the surface shape of the porous substrate 101 and forming a large number of pores (openings) 103. It is in the shape. In addition, in FIG. 3, although the substantially cylindrical hole is typically shown, the shape of the hole is not limited to this, and the hole has a diameter that changes in the middle, and the axial direction of the hole is oblique. It may be a complicated shape such as. Further, holes (openings, holes) having various sizes may be mixedly formed on the surface of the processing reference surface 33, and the catalyst material layer 102 is exposed on the surface portion around the holes. It is the catalyst standard processing surface. It is preferable that the hole has various shapes such as a perfect circle, an ellipse, and an indefinite shape. These holes (openings) are desirably arranged irregularly. In one example, the center of gravity of the hole is shifted in an oblique direction from a quadrilateral grid lattice (not shown) virtually set on the processing reference surface 33, or the hole is formed on the quadrilateral grid lattice (not shown). There may be sites that are not present (not shown), or there may be additional holes (not shown) in the unit cell. By arranging the holes irregularly in this way, it is possible to suppress the concentration of force at a specific place on the processing reference surface 33, and it is possible to disperse and average the force at the time of processing the substrate. Here, the case of a quadrilateral grid has been described, but the present invention is not limited to this, and may be a rhombic grid, a hexagonal grid, a honeycomb grid, or the like composed of parallelograms. It is desirable that the holes are not regularly arranged.

  Since the processing fluid can stay in the large number of hole groups, necessary and sufficient processing fluid can always be interposed between the main surface of the substrate M and the processing reference surface 33 during the catalyst reference etching. In addition, since this hole has a property of trapping foreign matter generated during processing etching, there is also an effect of reducing defects in this respect.

As a result of investigation by the inventor of setting various aperture ratios for the aperture ratio of the holes, when the area ratio is in the range of 20% to 80%, the surface can be smoothed and there are few defects. Further, it was found that when the average opening diameter of the porous surface is in the range of 0.1 μm or more and 100 μm or less, the surface can be smoothed and defects are reduced. The average opening diameter was measured from a scanning electron microscope (SEM) observation image of the porous surface, and the averaged opening diameter was defined as the average opening diameter.
From the viewpoint of surface roughness of the substrate main surface after processing and reduction of defects (particularly concave defects), the aperture ratio of the holes is preferably 20% or more and 70% or less, more preferably 25% or more and 60% by area ratio. % Or less, more preferably 25% or more and 40% or less.
Similarly, from the viewpoint of reducing the surface roughness of the substrate main surface after processing and reducing defects (particularly concave defects), the average opening diameter of the porous surface is preferably 10 μm to 80 μm, more preferably 20 μm to 70 μm. The following is desirable.

  As the porous base material, an elastic material is preferable in consideration of the point that it is difficult to be a source of foreign matters due to chipping or the like and hardly generate scratches. Here, the hardness range of the elastic body expressed by the modulus, the degree of compressive deformation, etc. is important. If the hardness is high, the surface of the substrate is likely to be damaged, and if the hardness is low, the processing rate is slow. In order to achieve both the prevention of scratches and the securing of the processing rate, the elastic body hardness of the porous base material or the porous catalyst portion with the catalyst formed thereon is in the range of less than 90 in Shore A hardness. It is desirable. The preferable range of the elastic body hardness of the porous catalyst portion is 50 or less, more preferably 20 or less, more preferably 10 or less in Shore A hardness.

  The method for forming the porous substrate is not particularly limited, but the foam formation method is suitable because it is an inexpensive and general-purpose method and the arrangement of the holes tends to be irregular. Moreover, as a porous base material of this foaming method, for example, urethane foam is suitable because of its versatility and appropriate hardness.

  The overall shape of the catalyst platen is not particularly limited. For example, the outer shape of a disk, a sphere, a cylinder, a cone, or a pyramid can be used. The surface shape of the portion of the catalyst surface plate on which the processing reference surface is formed is not particularly limited. For example, a flat, hemispherical, or rounded shape can be used.

  The processing fluid supply means 4 includes a supply pipe 41 extending from the outside to the inside of the chamber 6, and an injection nozzle that is provided at the tip of the lower end of the supply pipe 41 and jets the processing fluid toward the processing reference surface 33. 42. The supply pipe 41 is connected to, for example, a processing fluid storage tank (not shown) and a pressurizing pump (not shown) provided outside the chamber 6. The processing fluid is supplied to the injection nozzle 42 through the supply pipe 41, and is supplied from the injection nozzle 42 onto the processing reference surface 33. The method for supplying the processing fluid is not limited to this, and the processing fluid may be supplied from the substrate M side.

  The drive means 5 is connected to the upper end of the head rod 20 of the substrate support means 2 and extends to the periphery of the chamber 6 and extends in a direction parallel to the main surface of the substrate M attracted and held by the vacuum chuck portion 22; A shaft portion 52 that supports the end portion of the arm portion 51 extending to the periphery of the chamber 6 and extends in a direction perpendicular to the main surface of the substrate M attracted and held by the vacuum chuck portion 22, and a base that supports the lower end of the shaft portion 52 A portion 53 and a guide 54 that is disposed around the chamber 6 and defines a movement path of the base portion 53 are provided. The arm portion 51 can move in the longitudinal direction (see a double arrow C in FIGS. 1 and 2). The shaft part 52 can move the arm part 51 up and down by moving in the longitudinal direction (see a double-headed arrow D in FIG. 1). The base portion 53 can turn the arm portion 51 by rotating it by a predetermined angle about an axis perpendicular to the main surface of the substrate M held by the vacuum chuck portion 22 (FIG. 1). , 2 (see double arrow E). The guide 54 is disposed in a direction (first direction and second direction) parallel to two adjacent sides of the substrate M attracted and held by the vacuum chuck portion 22, and forms an L-shaped movement path of the base portion 53. To do. The base portion 53 moves along the guide 54 in the first direction, thereby moving the arm portion 51 in the first direction (see the double arrow F in FIG. 2), and the guide 54 in the second direction. The arm portion 51 can be moved in the second direction by moving along (see the double arrow G in FIG. 2). By such movement of the arm portion 51, the main surface of the substrate M attracted and held by the vacuum chuck portion 22 can be disposed at a predetermined position on the processing reference surface 33 of the catalyst surface plate 31.

  The relative motion means 7 is provided on the arm portion 51 of the drive means 5 and includes a rotation drive means (not shown) for rotating the head rod 20 of the substrate support means 2. By rotating the head rod 20, the substrate M sucked and held by the vacuum chuck portion 22 of the substrate support means 2 can be rotated with the head rod 20 as the rotation center (see arrow B in FIGS. 1 and 2). ).

  The relative motion means 7 supports a catalyst surface plate mounting portion (not shown) to which the catalyst surface plate 31 is mounted, a shaft portion 71 extending to the outside of the chamber 6 through the opening 61, and the shaft portion 71. Rotation drive means (not shown) for rotating the. The shaft portion 71 extends in a direction perpendicular to the processing reference surface 33 of the catalyst surface plate 31 and is perpendicular to the processing reference surface 33 of the catalyst surface plate 31 by a rotation driving means (not shown). (See arrow A in FIG. 1). The center of the catalyst surface plate 31 is located in the extending direction of the rotation center of the shaft portion 71. As the shaft portion 71 rotates, the catalyst surface plate mounting portion (not shown) supported by the shaft portion 71 rotates around the center thereof, and further, the catalyst surface plate mounting portion (not shown) The fixed catalyst surface plate 31 rotates around the center thereof.

  As a control method for securing the machining allowance as set, for example, various local processing conditions (processing pressure, rotational speed (catalyst platen, substrate), processing fluid, Flow rate), machining time and machining allowance are determined, the machining condition and machining time to be the desired machining allowance are determined, and the machining allowance is controlled by controlling the machining time. it can. The method is not limited to this, and various methods may be selected as long as the machining allowance can be ensured as set.

When performing processing by catalyst-based etching using the substrate processing apparatus shown in FIGS. 1 and 2, first, the lower surface M1 used as the main surface is directed downward and the upper surface M2 is adsorbed to the vacuum chuck 22. Hold.
Thereafter, the arm part 51 moves in the longitudinal direction (double arrow C), the arm part 51 pivots (double arrow E), the arm part 51 moves in the first direction (double arrow F), and the arm part 51 moves in the second direction ( By the double arrow G), the lower surface M1 of the substrate M is arranged so as to face the processing reference surface 33 of the substrate surface creation means 3.

Thereafter, the processing fluid is supplied from the spray nozzle 42 onto the lower surface M1 while rotating the processing reference surface 33 and the lower surface M1 at a predetermined rotational speed by rotating the shaft portion 71 and the head rod 20 at a predetermined rotational speed. The processing fluid is interposed between the lower surface M1 and the processing reference surface 33. In this state, the lower surface M1 is moved closer to the processing reference surface 33 by the vertical movement of the arm portion 51 (double arrow D). At that time, the load applied to the substrate M is controlled to a predetermined value by a load control means (not shown).
Thereafter, when the predetermined machining allowance is reached, the rotation of the shaft portion 71 and the head rod 20 and the supply of the processing fluid are stopped. Then, the lower surface M1 is separated from the processing reference surface 33 by a predetermined distance by the vertical movement of the arm portion 51 (double arrow D).

  The substrate M is manufactured through the substrate preparation process and the substrate processing process.

According to the substrate manufacturing method of the first embodiment, an organic alkaline aqueous solution is used as a processing fluid interposed between the substrate M to be processed and the processing reference surface 33 of the catalyst substance when processing by the catalyst reference etching is performed. Therefore, even when a relatively high load (processing pressure) is applied, it is possible to suppress the occurrence of a water drainage phenomenon. Thus, when the substrate M and the processing reference surface 33 move relative to each other, The process fluid can always be interposed between the two, and the formation of silicate can be suppressed, and thereby, micro-sleeve scratches, micro-surface roughness, micro-protrusions that can be concave defects on the main surface of the substrate M. Defects can be suppressed. For this reason, it is possible to provide a substrate having a low-defect and high-smooth main surface.
Further, according to the substrate processing apparatus 1 used in the substrate manufacturing method of the first embodiment, the substrate M supported by the substrate supporting means 2 is transferred to the chamber 6 by the linkage of the driving means 5 and the relative motion means 7. It can be moved in and out. For this reason, the substrate M is supported outside the chamber 6 by the substrate support means 2, the substrate M is moved into the chamber 6 by the linkage of the driving means 5 and the relative motion means 7, and after processing by catalyst reference etching. The substrate M can be moved to a cleaning device (not shown) outside the chamber 6 by the linkage of the driving means 5 and the relative motion means 7. Such a series of flows can be performed in a state where the substrate M is supported by the substrate support means 2, so that the main surface (particularly, the lower surface M <b> 1) of the substrate M is processed particularly after processing by the catalyst-based etching. It is possible to prevent adhesion of impurities and generation of scratches.

In this embodiment, the present invention is applied to a substrate processing apparatus of the type in which the main surface of the substrate M is pressed against the processing reference surface 33 of the substrate surface creation means 3 from above. The present invention can also be applied to a substrate processing apparatus that presses the surface against the main surface of the substrate from above.
In this embodiment, the present invention is applied to a substrate processing apparatus that processes one side of a substrate. However, the present invention can also be applied to a substrate processing apparatus that processes both surfaces of a substrate simultaneously. In this case, a carrier that is a member that holds the side surface of the substrate is used as the substrate support means.
In this embodiment, the present invention is applied to a substrate processing apparatus that supplies a processing fluid from the outside of the chamber toward the processing reference plane. However, the processing fluid supply means is provided in the substrate surface creation means, and the processing fluid is provided. The present invention can also be applied to the case where the processing fluid is supplied from the supply means, or the case where the processing fluid supply means is provided in the substrate support means and the processing fluid is supplied from the substrate support means. The present invention can also be applied to the case where the processing fluid is stored in the chamber, and the processing based on the catalyst reference etching is performed in a state where the substrate surface creation means and the substrate support means are placed in the processing fluid.

In this embodiment, the present invention is applied to a substrate processing apparatus of a type that relatively moves the processing reference surface 33 and the main surface by rotating both the processing reference surface 33 and the main surface. The present invention can also be applied to a substrate processing apparatus of a type in which the processing reference surface 33 and the main surface are moved relative to each other by a method.
In this embodiment, the present invention is applied to a single-wafer type substrate processing apparatus that processes substrates one by one. However, the present invention is also applied to a batch-type substrate processing apparatus that simultaneously processes a plurality of substrates. Applicable. Moreover, although the case where it processed over the main surface whole surface of a board | substrate was shown here, only the local processing which processes only a predetermined local part may be performed as needed, and these processes may be used together. Good.

Embodiment 2. FIG.
In Embodiment 2, a method for manufacturing a substrate with a multilayer reflective film will be described.

  In the second embodiment, a multilayer reflective film in which high refractive index layers and low refractive index layers are alternately laminated on the main surface of the substrate M manufactured by the method described in the substrate manufacturing method of the first embodiment. Then, a substrate with a multilayer reflective film is produced, or a protective film is formed on the multilayer reflective film to produce a substrate with a multilayer reflective film.

  According to the method for manufacturing a substrate with a multilayer reflective film according to the second embodiment, a substrate with a multilayer reflective film is manufactured using the substrate M obtained by the method for manufacturing a substrate according to the first embodiment. Can be prevented, and a substrate with a multilayer reflective film having desired characteristics can be manufactured.

  In the case of a substrate with a multilayer film for EUV lithography, it is necessary to pay attention to unevenness due to pits and bumps on the substrate surface and phase defects due to defects in the multilayer film. The inspection sensitivity of the phase defect is higher when the inspection is performed at the stage after the multilayer film is formed than at the substrate stage. At this time, if the surface of the substrate is rough and the surface smoothness is low, even if the inspection is performed after the multilayer film is formed, it becomes a background noise at the time of phase defect inspection and the inspection sensitivity is lowered. According to the embodiment of the present invention, since the surface smoothness including the surface of the multilayer film is high in addition to the surface of the substrate, the phase defect inspection sensitivity can be improved, and the substrate with the multilayer reflection film having high phase defect management quality can be obtained. It can be manufactured.

Embodiment 3 FIG.
In Embodiment 3, a mask blank manufacturing method will be described.

  In this third embodiment, a binary mask blank is manufactured by forming a light shielding film as a transfer pattern thin film on the main surface of the substrate M manufactured by the method described in the substrate manufacturing method of the first embodiment. Alternatively, a half-tone phase shift mask blank is manufactured by forming a light semi-transmissive film as a transfer pattern thin film, or a half-tone phase shift mask by sequentially forming a light semi-transmissive film and a light-shielding film as a transfer pattern thin film. A blank is manufactured.

  In the third embodiment, an absorber film as a transfer pattern thin film is formed on the protective film of the multilayer reflective film-coated substrate manufactured by the method described for the multilayer reflective film-coated substrate of the second embodiment. Alternatively, a protective film and an absorber film as a transfer pattern thin film are formed on the multilayer reflective film of the substrate with the multilayer reflective film, and a back conductive film is formed on the back surface on which the multilayer reflective film is not formed. A mold mask blank is manufactured.

  According to the third embodiment, the substrate M obtained by the substrate manufacturing method of the first embodiment or the substrate with the multilayer reflective film obtained by the method of manufacturing the substrate with the multilayer reflective film of the second embodiment is used. Since the mask blank is manufactured, it is possible to prevent deterioration of characteristics due to substrate factors, and it is possible to manufacture a mask blank having desired characteristics.

Embodiment 4 FIG.
In the fourth embodiment, a method for manufacturing a transfer mask will be described.

  In the fourth embodiment, an exposure / development process is performed on the transfer pattern thin film of the binary mask blank, phase shift mask blank, or reflective mask blank manufactured by the method described in the mask blank manufacturing method of the third embodiment. To form a resist pattern. Using this resist pattern as a mask, the transfer pattern thin film is etched to form a transfer pattern to manufacture a transfer mask.

  According to the fourth embodiment, since the transfer mask is manufactured using the mask blank obtained by the mask blank manufacturing method of the third embodiment, it is possible to prevent the deterioration of the characteristics due to the substrate factor. A transfer mask having the above characteristics can be manufactured.

≪Comparative test of substrate surface roughness due to different types of alkaline aqueous solution≫
Before describing the examples, the results of comparing the surface roughness of the low thermal expansion glass substrate in an inorganic alkaline aqueous solution (NaOH, KOH) and an organic alkaline aqueous solution (TMAH) will be described.
First, three low thermal expansion glass substrates having approximately the same root mean square roughness (RMS) before the comparative test were prepared.
Alkaline aqueous solutions (NaOH, KOH, TMAH) adjusted to pH 11 were accommodated in tanks of the same size, and the low thermal expansion glass substrate was placed in each tank and immersed for 24 hours. Thereafter, each low thermal expansion glass substrate was taken out of the tank, put on a spin cleaning machine, rinsed with deionized water for 5 minutes, and dried. The surface roughness of the main surface of each low thermal expansion glass substrate thus obtained was measured using an atomic force microscope (AFM) with respect to a 1 μm × 1 μm region at the center of the substrate. FIG. 4 shows a comparison of surface roughness with three types of alkaline aqueous solutions. The vertical axis | shaft of FIG. 4 has shown the root mean square roughness (RMS) after a comparative test in arbitrary units.
In FIG. 4, the RMS of TMAH was taken as a reference, and when this was set to 1, the RMS of NaOH was about 1.4 times that of TMAH, and the RMS of KOH was about 1.7 times that of TMAH.
Therefore, it was confirmed by the above-described comparative test that TMAH as the organic alkali aqueous solution can suppress the deterioration of the surface roughness of the substrate main surface as compared with NaOH and KOH as the inorganic alkaline aqueous solution.

Hereinafter, based on an Example, this invention is demonstrated more concretely.
In addition, the table | surface which shows the content of the evaluation conditions before and after each process conditions about the following Examples 1-5 and Comparative Examples 1 and 2 is shown in FIG.

Example 1.
A. Production of glass substrate Substrate Preparation Step A low thermal expansion glass substrate, which is a 6025 size (152.4 mm × 152.4 mm × 6.35 mm) TiO ₂ —SiO ₂ glass substrate with the main surface and back surface polished, was prepared. The TiO ₂ —SiO ₂ glass substrate is obtained through the following rough polishing process, precision polishing process, ultraprecision polishing process, local processing process, and touch polishing process.

(1) Rough polishing process Step 10 glass substrates that have undergone end chamfering and grinding were set in a double-side polishing apparatus, and rough polishing was performed under the following polishing conditions. A set of 10 sheets was performed twice, and a total of 20 glass substrates were roughly polished. The processing load and polishing time were adjusted as appropriate.
Polishing slurry: Aqueous solution containing cerium oxide (average particle size 2 to 3 μm) Polishing pad: Hard polisher (urethane pad)
After the rough polishing, in order to remove the abrasive grains adhering to the glass substrate, the glass substrate was immersed in a cleaning tank and cleaned by applying ultrasonic waves.

(2) Precision polishing process step Ten glass substrates after rough polishing were set in a double-side polishing apparatus, and precision polishing was performed under the following polishing conditions. A 10-sheet set was performed twice, and a total of 20 glass substrates were precisely polished. The processing load and polishing time were adjusted as appropriate.
Polishing slurry: Aqueous solution containing cerium oxide (average particle size 1 μm) Polishing pad: Soft polisher (suede type)
After the precision polishing, in order to remove abrasive grains adhering to the glass substrate, the glass substrate was immersed in a cleaning tank and cleaned by applying ultrasonic waves.

(3) Ultra-precision polishing process Step 10 glass substrates that had been subjected to precision polishing were again set in a double-side polishing apparatus, and ultra-precision polishing was performed under the following polishing conditions. A set of 10 sheets was performed twice and a total of 20 glass substrates were subjected to ultra-precision polishing. The processing load and polishing time were adjusted as appropriate.
Polishing slurry: alkaline aqueous solution (pH 10.2) containing colloidal silica
(Colloidal silica content 50wt%)
Polishing pad: Super soft polisher (suede type)
After ultra-precision polishing, the glass substrate was immersed in a cleaning tank containing an alkali cleaning solution of sodium hydroxide and cleaned by applying ultrasonic waves.

(4) Local processing step The flatness of the main surface and the back surface of the glass substrate after the rough polishing processing step, the precision polishing processing step, and the ultraprecision polishing processing step was measured using a flatness measuring device (UltraFlat200 manufactured by Tropel). . The flatness measurement was performed at a point of 1024 × 1024 with respect to an area of 148 mm × 148 mm excluding the peripheral area of the glass substrate. The measurement results of the flatness of the main surface and the back surface of the glass substrate were stored in a computer as height information (uneven shape information) with respect to the virtual absolute plane for each measurement point. The virtual absolute plane is a plane having a minimum value when the distance from the virtual absolute plane to the substrate surface is squared with respect to the entire flatness measurement region.
After that, the obtained uneven shape information was compared with the standard values of the flatness of the main surface and the back surface required for the glass substrate, and the difference was calculated by a computer for each predetermined region of the main surface and the back surface of the glass substrate. . This difference becomes a necessary removal amount (processing allowance) of each predetermined region in local surface processing.

Then, the processing conditions of the local surface processing according to the required removal amount were set for every predetermined area | region of the main surface and back surface of a glass substrate. The setting method is as follows. Using a dummy substrate in advance, the dummy substrate is processed at a certain point (spot) without moving the substrate for a certain period of time in the same manner as in actual processing, and the shape thereof is measured with a flatness measuring device (UltraFlat 200 manufactured by Tropel). Measurement was performed, and the processing volume at the spot per unit time was calculated. Then, the scanning speed for raster scanning of the glass substrate was determined according to the processing volume at the spot per unit time and the necessary removal amount of each predetermined area calculated as described above.
Then, the main surface and the back surface of the glass substrate were locally surface-treated by a magnet viscoelastic fluid polishing (MRF) using a substrate finishing device according to the processing conditions set for each predetermined region. At this time, a magnetic polishing slurry containing cerium oxide polishing particles was used.

  Thereafter, the glass substrate was immersed in a cleaning tank containing an aqueous hydrochloric acid solution having a concentration of about 10% (temperature: about 25 ° C.) for about 10 minutes, followed by rinsing with pure water and drying with isopropyl alcohol (IPA).

(5) Touch polishing process In order to improve the smoothness of the main surface and back surface of the glass substrate that has been roughened by the local processing process, the main surface and back surface of the glass substrate are only minute amounts by low-load mechanical polishing using a polishing slurry. Polished. This polishing is performed by setting a glass substrate held by a carrier between upper and lower polishing surface plates to which a polishing pad larger than the size of the substrate is attached, and containing a colloidal silica abrasive grain (average particle diameter of 50 nm). The glass substrate was revolved while rotating in the upper and lower polishing surface plates while feeding.
Thereafter, the glass substrate was immersed in an HF solution and washed by applying ultrasonic waves.

2. Substrate Processing Step Next, using the substrate processing apparatus shown in FIGS. 1 and 2, the main surface of the glass substrate after the touch polishing step was processed by catalyst-based etching.

In this embodiment, a disk-shaped surface plate main body 32 made of stainless steel (SUS), a foamed urethane pad formed on the entire surface of the surface plate main body 32 so as to cover the surface plate main body 32, and a glass substrate are opposed to each other. A catalyst surface plate 31 provided with a processing reference surface 33 made of Pt (platinum) formed on the entire surface of the urethane pad on the side was used. Here, the diameter of the catalyst platen is 600 mm. The hardness of this urethane foam pad is 3 by Shore A evaluation and is soft. The catalyst reference surface 33 was formed by performing sputtering film formation in an Ar (argon) gas atmosphere using a Pt target on this pad. The film thickness of the deposited Pt is 100 nm. The holes formed in the catalyst reference surface 33 vary in size, and the arrangement is irregularly arranged outside the lattice arrangement. Incidentally, the average opening diameter of the holes in this case was 32.5 μm, and the opening ratio (average value) was 30%.
The processing conditions are as follows.
Processing fluid: Tetramethylammonium hydroxide (TMAH) aqueous solution (pH 11)
Number of rotations of the shaft portion 71 (number of rotations of the glass substrate): 10.3 rotations / minute Number of rotations of the catalyst surface plate mounting portion (not shown) (number of rotations of the catalyst surface plate 31): 10 rotations / minute Processing pressure: 150 hPa
Processing allowance: 30nm

First, the glass substrate was held with its main surface facing downward and its back surface adsorbed to the vacuum chuck portion 22.
Thereafter, the longitudinal movement of the arm 51 (double arrow C), the swing movement of the arm 51 (double arrow E), the first movement of the arm 51 (double arrow F), and the second movement of the arm 51 ( The glass substrate was arranged so that the main surface of the glass substrate faces the processing reference surface 33 of the catalyst surface plate 31 by the double arrow G). The arrangement position of the glass substrate is a position at which the entire main surface of the glass substrate can contact or approach the processing reference surface 33 of the catalyst platen 31 when the glass substrate and the catalyst platen 31 are rotated. .

  Thereafter, the glass substrate is rotated at a rotation speed of 10.3 rotations / minute and the catalyst surface plate 31 is rotated at a rotation speed of 10 rotations / minute. Here, the glass substrate and the catalyst platen 31 are rotated so that the rotation direction of the glass substrate and the rotation direction of the catalyst platen 31 are opposite to each other. Thereby, a peripheral speed difference can be taken between them, and the processing efficiency by catalyst reference | standard etching can be improved. Moreover, both rotation speeds are set to be slightly different. Accordingly, the main surface of the glass substrate can be moved relative to the processing reference surface 33 of the catalyst surface plate 31 so as to draw different trajectories, and the processing efficiency by the catalyst reference etching can be increased.

While rotating the glass substrate and the catalyst surface plate 31, the TMAH aqueous solution is supplied from the injection nozzle 42 onto the processing reference surface 33 of the catalyst surface plate 31, and the TMAH aqueous solution is supplied between the main surface of the glass substrate and the processing reference surface 33. Intervened. In this state, the main surface of the glass substrate was brought into contact with or brought close to the processing reference surface 33 of the catalyst surface plate 31 by the vertical movement of the arm portion 51 (double arrow D). At that time, the load (working pressure) applied to the glass substrate was controlled to 150 hPa by a load control means (not shown).
Thereafter, when the machining allowance reached 30 nm, the rotation of the glass substrate and the catalyst platen 31 and the supply of the TMAH aqueous solution were stopped. Then, the main surface of the glass substrate was separated from the processing reference surface 33 of the catalyst surface plate 31 by a predetermined distance by the vertical movement of the arm portion 51 (double arrow D).
Thereafter, the operation of the vacuum device (not shown) was stopped, and the glass substrate was removed from the vacuum chuck portion 22.

Thereafter, the glass substrate removed from the vacuum chuck portion 22 was washed as follows. First, pure water cleaning was performed to remove the TMAH aqueous solution remaining on the glass substrate, followed by aqua regia cleaning, hydrochloric acid cleaning, and alkali cleaning, followed by rinsing with pure water and drying.
In this way, a glass substrate was produced.

3. Evaluation The surface roughness of the main surface of the glass substrate before and after processing by catalyst-based etching was measured using an atomic force microscope (AFM) for a 1 μm × 1 μm region at the center of the substrate.
As shown in FIG. 5, the surface roughness of the main surface before processing was 0.157 nm in terms of root mean square roughness (RMS).
As shown in FIG. 5, the surface roughness of the main surface after processing was as good as 0.047 nm in terms of root mean square roughness (RMS). The surface roughness of the main surface was improved from 0.157 nm to 0.047 nm in terms of root mean square roughness (RMS) by catalyst-based etching.

For inspection of defects on the main surface of the glass substrate after processing by catalyst-based etching, a mask / blank defect inspection apparatus (Teron 610: manufactured by KLA-Tencor) is used for a 132 mm × 132 mm area excluding the peripheral area of the substrate. I went. The defect inspection was carried out under inspection sensitivity conditions capable of detecting a 21.5 nm size defect in terms of SEVD (Sphere Equivalent Volume Diameter). SEVD is the length of the diameter when the defect is assumed to be hemispherical.
As shown in FIG. 5, the number of concave defects on the main surface after processing was as small as 5 and the number of convex defects was as small as 6.
Moreover, when 20 glass substrates were produced by the method of Example 1, the total number and the surface roughness were good at root mean square roughness (RMS) of 0.049 nm or less, and the number of concave defects was 7 or less. Also, the number of convex defects was as small as 8 or less.
By the method of Example 1, a glass substrate having a low-defect and highly smooth main surface was stably obtained.

B. Next, a high refractive index layer (film thickness: 4.2 nm) made of a silicon film (Si) is formed on the main surface of the glass substrate thus produced by ion beam sputtering. A multilayer reflective film (thickness: 280 nm) is formed by alternately stacking 40 pairs of low refractive index layers (2.8 nm) made of a molybdenum film (Mo) alternately with one pair of high refractive index layer and low refractive index layer. Formed.
Thereafter, a protective film (thickness 2.5 nm) made of ruthenium (Ru) was formed on the multilayer reflective film by ion beam sputtering.
In this way, a substrate with a multilayer reflective film was produced.

About the obtained board | substrate with a multilayer reflective film, the reflectance of EUV light (wavelength 13.5nm) was measured with the EUV reflectance measuring apparatus.
Due to the high smoothness of the main surface of the glass substrate, the surface of the protective film also maintained high smoothness, and the reflectance was as high as 64%.
The defect inspection of the protective film surface of the obtained multilayer reflective film-coated substrate was performed in the same manner as the defect inspection of the glass substrate.
The number of concave defects on the surface of the protective film after processing was as small as eight and the number of convex defects was nine. The phase defect inspection was also performed. However, because of the high smoothness, the background noise at the time of inspection was small, and the phase defect inspection with high sensitivity could be performed.
By the method of Example 1, a substrate with a multilayer reflective film having a highly smooth protective film surface with low defects was obtained.

C. Production of Reflective Mask Blank Next, a tantalum boride (TaB) target is used on the protective film of the multilayer reflective film substrate thus produced, and argon (Ar) gas and nitrogen (N ₂ ) gas are used. Reactive sputtering is performed in a mixed gas atmosphere to form a lower absorber layer (film thickness 50 nm) made of tantalum boron nitride (TaBN), and tantalum boride (TaB) is further formed on the lower absorber film. Using a target, reactive sputtering is performed in a mixed gas atmosphere of argon (Ar) gas and oxygen (O ₂ ) gas to form an upper absorber layer (thickness 20 nm) made of tantalum boron oxide (TaBO). As a result, a layer absorber film (film thickness 70 nm) composed of a lower absorber layer and an upper absorber layer was formed.
Thereafter, a reaction in a mixed gas atmosphere of argon (Ar) gas and nitrogen (N ₂ ) gas using a chromium (Cr) target on the back surface of the substrate with the multilayer reflective film on which the multilayer reflective film is not formed. A back conductive film (thickness 20 nm) made of chromium nitride (CrN) was formed by reactive sputtering.
In this way, a reflective mask blank for EUV exposure, in which a highly smooth surface state with low defects was maintained, was produced.

D. Production of Reflective Mask Next, a chemically amplified resist for electron beam drawing (exposure) is applied onto the absorber film of the thus produced reflective mask blank by a spin coating method, and heating and cooling steps are performed. Then, a resist film having a thickness of 150 nm was formed.
Thereafter, a desired pattern was drawn on the formed resist film using an electron beam drawing apparatus, and then developed with a predetermined developer to form a resist pattern.
Thereafter, using this resist pattern as a mask, the absorber film was dry-etched to form an absorber film pattern on the protective film. As a dry etching gas, chlorine (Cl ₂ ) gas was used.
Thereafter, the remaining resist pattern was peeled off and washed.
In this way, a reflective mask for EUV exposure, in which a highly smooth surface state with low defects was maintained, was produced.

Example 2
A. Production of Glass Substrate In this example, a synthetic quartz glass substrate of 6025 size (152.4 mm × 152.4 mm × 6.35 mm) whose upper and lower surfaces were polished was prepared. The synthetic quartz glass substrate is obtained through the above-described rough polishing process, precision polishing process, and ultraprecision polishing process.
Otherwise, a glass substrate was produced in the same manner as in Example 1.

Similar to Example 1, the surface roughness of the main surface of the glass substrate before and after processing by catalyst-based etching was measured.
As shown in FIG. 5, the surface roughness of the main surface before processing was 0.127 nm in terms of root mean square roughness (RMS).
As shown in FIG. 5, the surface roughness of the main surface after processing was as good as 0.045 nm in terms of root mean square roughness (RMS). The surface roughness of the main surface was improved from 0.127 nm to 0.045 nm in terms of root mean square roughness (RMS) by catalyst-based etching.
Moreover, the defect inspection of the lower surface of the glass substrate after the process by catalyst reference | standard etching was performed similarly to Example 1. FIG.
As shown in FIG. 5, the number of concave defects on the main surface after processing was as small as four and the number of convex defects was six.
Further, when 20 glass substrates were produced by the method of Example 2, the total number and the surface roughness were as good as 0.046 nm or less in root mean square roughness (RMS), and the number of concave defects was also 6 or less. Also, the number of convex defects was as small as 8 or less.
By the method of Example 2, a glass substrate having a low-defect and highly smooth main surface was stably obtained.

B. Production of Halftone Phase Shift Mask Blank Next, a molybdenum silicide (MoSi) target is used on the main surface of the glass substrate thus produced, and argon (Ar), nitrogen (N ₂ ), and oxygen ( Reactive sputtering was performed in a mixed gas atmosphere with O ₂ ) to form a light semitransmissive film (film thickness: 88 nm) made of molybdenum silicide oxynitride (MoSiON). The film composition of the light translucent film analyzed by Rutherford backscattering analysis was Mo: 5 atomic%, Si: 30 atomic%, O: 39 atomic%, and N: 26 atomic%. The transmittance of the light semi-transmissive film with respect to the exposure light was 6%, and the phase difference caused by the exposure light passing through the light semi-transmissive film was 180 degrees.

Then, using a chromium (Cr) target on the light semi-transmissive film, reactive sputtering is performed in a mixed gas atmosphere of argon (Ar), carbon dioxide (CO ₂ ), nitrogen (N ₂ ), and helium (He). To form a chromium oxycarbonitride (CrOCN) layer (thickness 30 nm), and further, using a chromium (Cr) target, a mixed gas of argon (Ar) and nitrogen (N ₂ ) Reactive sputtering is performed in an atmosphere to form a chromium nitride (CrN) layer (film thickness: 4 nm), and a light-shielding layer comprising a laminate of a chromium oxycarbonitride (CrOCN) layer and a chromium nitride (CrN) layer Formed. Further, a chromium (Cr) target is used on the light shielding layer, and reactive sputtering is performed in a mixed gas atmosphere of argon (Ar), carbon dioxide (CO ₂ ), nitrogen (N ₂ ), and helium (He). Then, a surface antireflection layer (film thickness: 14 nm) made of chromium oxycarbonitride (CrOCN) was formed. In this way, a light shielding film composed of the light shielding layer and the surface antireflection layer was formed.
In this way, a halftone phase shift mask blank for ArF excimer laser exposure, which maintained a low-smooth and highly smooth surface state, was produced.

C. Production of halftone phase shift mask Next, a chemical amplification resist for electron beam drawing (exposure) is applied onto the light-shielding film of the halftone phase shift mask blank produced in this way by a spin coating method. Through a heating and cooling process, a resist film having a thickness of 150 nm was formed.
Thereafter, a desired pattern was drawn on the formed resist film using an electron beam drawing apparatus, and then developed with a predetermined developer to form a resist pattern.
Thereafter, using this resist pattern as a mask, the light shielding film was dry etched to form a light shielding film pattern on the light semi-transmissive film. As a dry etching gas, a mixed gas of chlorine (Cl ₂ ) and oxygen (O ₂ ) was used.

Thereafter, using the resist pattern and the light shielding film pattern as a mask, the light semi-transmissive film was dry-etched to form a light semi-transmissive film pattern. As the dry etching gas, a mixed gas of sulfur hexafluoride (SF ₆ ) and helium (He) was used.
Thereafter, the remaining resist pattern is peeled off, a resist film is applied again, pattern exposure is performed to remove an unnecessary light-shielding film pattern in the transfer region, and then the resist film is developed to form a resist pattern. .
Thereafter, wet etching was performed to remove an unnecessary light shielding film pattern.
Thereafter, the remaining resist pattern was peeled off and washed.
In this way, a halftone phase shift mask for ArF excimer laser exposure that maintains a low-defect and high-smooth surface state was produced.

  In this embodiment, the present invention is applied to a halftone phase shift mask and a phase shift mask blank having a light semi-transmissive film made of molybdenum silicide oxynitride (MoSiON). However, molybdenum silicide nitride (MoSiN) is used. The present invention can also be applied to a halftone phase shift mask or a phase shift mask blank having a light semi-transmissive film made of The present invention is not limited to halftone phase shift masks and phase shift mask blanks having a single-layer light semi-transmissive film, but also to halftone phase shift masks and phase shift mask blanks having a multi-layered light semi-transmissive film. The invention can be applied. Further, the present invention can be applied not only to a halftone phase shift mask and a phase shift mask blank having a multi-layered light shielding film, but also to a halftone phase shift mask and a phase shift mask blank having a single-layer light shielding film. . Further, the present invention can be applied not only to the halftone phase shift mask blank and the phase shift mask blank but also to a Levenson type phase shift mask blank, a phase shift mask blank, a chromeless type phase shift mask blank, and a phase shift mask blank.

  In this example, the present invention was applied to the case where the main surface of the glass substrate obtained through the rough polishing process, the precision polishing process, and the ultraprecision polishing process was subjected to processing by catalyst-based etching. However, the present invention can also be applied to the case where the main surface of the glass substrate obtained through the local processing step and the touch polishing step performed in Example 1 is processed by catalyst-based etching.

Example 3 -Example 5.
In these Examples 3 to 5, the load (processing pressure) applied to the glass substrate in the substrate processing step of Example 1 described above was set to 100 hPa, 70 hPa, and 50 hPa, respectively, by the same method as Example 1. A glass substrate and a substrate with a multilayer reflective film were prepared.
Similarly to Example 1, when 20 glass substrates were prepared for the above Examples 3 to 5, the total number and the surface roughness of the main surface were as shown in FIG. RMS) was as good as 0.053 nm or less. As for the number of defects, as shown in FIG. 5, in the case of Example 3, the number of concave defects on the main surface after processing in Example 3 is 8 and the number of convex defects is 5 although it is inferior to Example 1. There were few. In the case of Example 4, the number of concave defects on the main surface after processing in Example 4 was 10 and the number of convex defects was small, although it was inferior to Example 3. In the case of Example 5, although inferior to Example 4, the number of concave defects on the main surface after processing in Example 5 was 14 and the number of convex defects was as small as 5.
Furthermore, the reflective mask blank for EUV exposure and a reflective mask were produced like Example 1 using the board | substrate with a multilayer reflective film obtained by Examples 3-5.
As a result, in all of Examples 3 to 5, it was possible to obtain a reflective mask blank for EUV exposure and a reflective mask for EUV exposure that maintained a highly smooth surface state with low defects.

  Further, as is clear from the number of concave defects (pits) on the glass substrate after processing in Examples 1 and 3 to 5, the load (processing pressure) was 50 hPa (Example 5), 70 hPa (Example 4), In the case of 100 hPa (Example 3) and 150 hPa (Example 1), it was confirmed that the number of concave defects (pits) decreased as the load (working pressure) increased. This is because a liquid film composed of an organic alkaline aqueous solution (TMAH aqueous solution) interposed between the glass substrate and the processing reference surface is thinned with an increase in load (processing pressure), and the thinned liquid film is uniformly formed. In this state, the main surface of the glass substrate can be processed by catalyst-based etching, so the number of concave defects (pits) on the main surface of the glass substrate can be reduced, and the main surface is low and highly smooth. This is considered to indicate that a glass substrate having a surface can be obtained.

Comparative Example 1
In Comparative Example 1, a glass substrate and a multilayer reflective film were formed in the same manner as in Example 1 except that KOH (pH 11) was used instead of the TMAH aqueous solution used as the processing fluid in the substrate processing step of Example 1. An attached substrate was produced.

Similar to Example 1, the surface roughness of the main surface of the glass substrate before and after processing by catalyst-based etching was measured.
As shown in FIG. 5, the surface roughness of the main surface after processing was insufficient as 0.071 nm in terms of root mean square roughness (RMS).
Moreover, the defect inspection of the main surface of the glass substrate after the process by catalyst reference | standard etching was performed similarly to Example 1. FIG.
As shown in FIG. 5, the number of concave defects on the main surface after processing was as large as 24 and the number of convex defects was 81.
Moreover, when 20 glass substrates were produced by the method of Comparative Example 1, the surface roughness of the main surface was 0.060 nm or more in terms of root mean square roughness (RMS), and the number of concave defects was 23 or more. The number of convex defects was as high as 80 or more.
Thus, Comparative Example 1 has a lower root mean square roughness (RMS) of the main surface after processing than Example 1, and the silicate produced by using KOH becomes a minute foreign matter, resulting in a convex defect. It turns out that there are many pieces.
For this reason, the glass substrate which has a low-defect and highly smooth main surface by the method of the comparative example 1 was not obtained.

In the same manner as in Example 1, the reflectance of EUV light (wavelength: 13.5 nm) was measured for the obtained substrate with a multilayer reflective film.
Due to the insufficient smoothness of the main surface of the glass substrate, the surface of the protective film was also insufficiently smooth, and the reflectance was 63%, which was lower than that of Example 1.
Moreover, the defect inspection of the protective film surface of the obtained board | substrate with a multilayer reflective film was performed similarly to Example 1. FIG.
The number of concave defects on the surface of the protective film was as large as 30 and the number of convex defects was as large as 86.
By the method of Comparative Example 1, a substrate with a multilayer reflective film having a highly smooth protective film surface with low defects was not obtained.
Moreover, the reflective mask blank and reflective mask for EUV exposure which have a low defect and a highly smooth surface were not obtained by the method of Comparative Example 1.

Comparative Example 2
In Comparative Example 2, the same method as in Example 3 was used except that pure water was used instead of the TMAH aqueous solution used as the processing fluid in the substrate processing step of Example 3 where the load (processing pressure) was 100 hPa. A glass substrate and a substrate with a multilayer reflective film were prepared.

Similar to Example 3 based on the method of Example 1, the surface roughness of the main surface of the glass substrate before and after processing by catalyst-based etching was measured.
As shown in FIG. 5, the surface roughness of the main surface after processing was 0.052 nm in terms of root mean square roughness (RMS).
Moreover, the defect inspection of the main surface of the glass substrate after the process by catalyst reference | standard etching was performed similarly to Example 3 based on the method of Example 1. FIG.
As shown in FIG. 5, the number of concave defects on the main surface after processing was as large as 311 and the number of convex defects was 114.
Further, when 20 glass substrates were produced by the method of Comparative Example 2, the surface roughness was 0.050 nm or more in terms of root mean square roughness (RMS), and the number of concave defects was 305 or more. The number was as large as 108 or more.
Thus, unlike Example 3, Comparative Example 2 has a large number of concave defects and convex defects because a water drainage phenomenon occurred between the main surface of the glass substrate and the processing reference surface 33 of the catalyst surface plate 31. I understood that.
For this reason, a glass substrate having a low-defect and high-smooth main surface could not be obtained by the method of Comparative Example 2.

In the same manner as in Example 3 in accordance with the method of Example 1, the reflectance of EUV light (wavelength: 13.5 nm) was measured for the obtained substrate with a multilayer reflective film.
Due to the insufficient smoothness of the main surface of the glass substrate, the surface of the protective film was also insufficiently smooth, and the reflectance was 63%, which was lower than that of Example 1.
Moreover, the defect test | inspection of the protective film surface of the obtained board | substrate with a multilayer reflective film was performed similarly to Example 3 based on the method of Example 1. FIG.
The number of concave defects on the surface of the protective film was as large as 322 and the number of convex defects was 123.
By the method of Comparative Example 2, a substrate with a multilayer reflective film having a highly smooth protective film surface with low defects was not obtained.
In addition, the reflective mask blank and reflective mask for EUV exposure having a low defect and a high smooth surface were not obtained by the method of Comparative Example 2.

  In the above-described embodiment, the present invention is applied to the case where the main surface of the reflective mask blank substrate or the phase shift mask blank substrate is processed by catalyst-based etching, but the glass for magnetic recording media is used. The present invention can also be applied to a case where a main surface of a substrate, a binary mask blank, or a nanoimprint mask blank is processed by catalyst-based etching.

DESCRIPTION OF SYMBOLS 1 ... Substrate processing apparatus, 2 ... Substrate support means, 3 ... Substrate surface creation means, 4 ... Processing fluid supply means, 5 ... Drive means, 6 ... Chamber, 7 ... Relative motion means, 8 ... Load control means, 20 ... Head Rod, 21 ... Head part, 22 ... Vacuum chuck part, 31 ... Catalyst surface plate, 32 ... Surface plate body, 33 ... Processing reference plane, 41 ... Supply pipe, 42 ... Injection nozzle, 51 ... Arm part, 52 ... Shaft part 53 ... Base part, 54 ... Guide, 61 ... Opening part, 62 ... Discharge port, 63 ... Bottom part, 71 ... Shaft part, M ... Substrate, M1 ... Lower surface, M2 ... Upper surface, 101 ... Porous substrate, 102 ... Catalytic substance, 103 ... hole (opening).

Claims (9)

A substrate preparation step of preparing a substrate having a main surface made of a material containing silicon oxide;
The processing reference surface of the catalytic substance and the main surface are brought into contact with or close to each other, and the main surface and the processing reference surface are moved relative to each other while a processing fluid is interposed between the processing reference surface and the main surface. A step of catalytically etching the main surface based on a hydrolysis reaction between the active species generated on the processing reference surface and the main surface.
The method of manufacturing a substrate, wherein the processing fluid includes an organic alkaline aqueous solution.   The organic alkali aqueous solution is an aqueous solution containing at least one of tetramethylammonium hydroxide (TMAH), tetraethylammonium hydroxide (TEAH), and tetrabutylammonium hydroxide (TBAH). The manufacturing method of the board | substrate of description. The method for manufacturing a substrate according to claim 1 , wherein the processing fluid does not substantially exhibit solubility in the normal state with respect to the substrate.   4. The substrate manufacturing method according to claim 1, wherein the processing reference surface has a porous surface, and the porous surface is formed of the catalyst material.   The substrate manufacturing method according to claim 4, wherein a load of 50 hPa or more is applied to the substrate.   The method for manufacturing a substrate according to claim 1, wherein the substrate is a mask blank substrate.   A method for producing a substrate with a multilayer reflective film, comprising: forming a multilayer reflective film on a main surface of the substrate obtained by the method for producing a substrate according to claim 6.   On the main surface of the substrate obtained by the method for producing a substrate according to claim 6, or on the multilayer reflective film of the substrate with a multilayer reflective film obtained by the method for producing a substrate with a multilayer reflective film according to claim 7. And a method of manufacturing a mask blank, comprising forming a transfer pattern thin film.   A method for producing a transfer mask, comprising: patterning a transfer pattern thin film of a mask blank obtained by the method for producing a mask blank according to claim 8 to form a transfer pattern.

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