TW201327031A - Manufacturing method of transfer mask - Google Patents

Abstract

To provide a manufacturing method of transfer mask capable of inhibiting occurrence of black defects in the transfer mask. The manufacturing method of transfer mask lines is to form a film having the transfer pattern on the substrate. The thin film is made of materials that can be subjected to dry etching, comprising: a preparation step to prepare a mask substrate having a resist film formed on the thin film; an exposure step to expose the transfer pattern on the resist film; a development step to develop the exposed resist film, using a developer containing etching hinder factor substance with a concentration higher than 0.3ppb and pH > 8 for the development treatment; a first rinsing step to rinse the substrate after the developing treatment, using a first rinsing solution containing etching hinder factor substance with a concentration less than 0.3ppb and pH > 8; and a second rinsing step, after the first rinsing step, using a second rinsing solution containing an etching hinder factor substance with a concentration less than 0.3ppb and 6 < pH < 8.

Description

Manufacturing method of transfer mask

The present invention relates to a method of manufacturing a mask for transfer.

In general, a manufacturing process such as a semiconductor uses a photolithography method to form a fine pattern. When this photolithography method is implemented, a transfer mask is used in the fine pattern transfer process. This transfer mask is generally produced by forming a desired fine pattern on a light-shielding film as a mask base of an intermediate. For this reason, the characteristics of the light-shielding film formed as the mask base of the intermediate body almost directly affect the performance of the transfer mask. In the conventional light shielding film of the mask base, a light shielding film made of a Cr-containing material is generally used. Moreover, in recent years, a mask base having a light-shielding film made of a lanthanoid material has been developed, and evaluation of the performance of a transfer mask manufactured using the same has been carried out.

When a mask for transfer is manufactured using a mask base, the transfer pattern is formed on the film by etching the film with the resist pattern as a mask. The process of forming a resist pattern on a film generally performs a resist coating process, an exposure (drawing) process, a post-exposure baking process, a development process, and a cleaning process. In the developing step, the resist of the exposed portion (positive type) or the non-exposed portion (negative type) is removed by the developing solution by contacting the developing solution with the resist.

Patent Document 1 discloses a method for suppressing collapse or damage of a resist pattern which occurs in a rinsing step or a drying step in a developing step, and does not require an ultraviolet ray irradiation device or the like, but can be developed without damaging a resist pattern. Invention of a pharmaceutical agent and a developing method using the same.

Further, Patent Document 1 discloses that development at pH 10 or higher is disclosed. After the liquid is developed, the invention is immersed in a rinse composition having a pH of 11 or less or an aqueous solution thereof, followed by a development method in which the water is rinsed with pure water.

[Previous Technical Literature]

[Patent Literature]

Patent Document 1: Japanese Laid-Open Patent Publication No. Hei 11-295902

In the etching process for etching the mask substrate, first, the resist film formed on the mask substrate is subjected to drawing, development, and rinsing to form a resist pattern. Next, the mask pattern is used as a mask, and the light shielding film is dry etched to form a thin film pattern. Finally, the transfer mask is completed by removing the resist film. The completed transfer mask is inspected for the presence or absence of black defects and white defects by a mask defect inspection device. When a defect is found, a correction technique such as EB irradiation is used to correct the defective portion.

When a mask for transfer is produced using a mask substrate having a light-shielding film made of a lanthanoid material, black defects occur more than when a mask substrate having a light-shielding film made of a chrome-based material is used. The problem. In the defect inspection performed on the mask substrate having the light-shielding film of the lanthanoid material at the stage before the resist coating, the number of defects is the number within the allowable range. That is, although the defect inspection of the mask base was not detected, it is known that there are many minute black defects detected at the first time in the defect inspection after the mask for the transfer is manufactured using the mask substrate. This micro black defect is present on the surface of the substrate and has a size of 20 to 100 nm, and the height corresponds to the film thickness of the film. This is the case where the transfer mask after the DRAM half pitch of 32 nm is fabricated under the semiconductor design rule for the first time. Discovered. Such tiny black defects are fatal defects in the manufacture of semiconductor components, so they must be completely removed. However, in the case where the number of defects exceeds 50, the burden of defect correction becomes large, and the story There are difficulties in correcting defects in real time. Further, in recent years, in the high integration of semiconductor elements, the defect of the thin film pattern formed by the transfer mask (for example, OPC pattern), miniaturization (for example, an assist bar), and narrowing are eliminated. ‧The correction also has limits and becomes a problem.

In view of the above, the present invention has been made in an effort to provide a method for producing a transfer mask which can suppress the occurrence of black defects in a transfer mask.

The inventors of the present invention investigated the cause of occurrence of minute black defects in the above-mentioned transfer mask, and found that the etching inhibiting factor substance adhering to the film in the developing step of the resist is a cause, and the etching inhibiting factor substance is contained in the resist. The developer used in the development of the agent (the details of the etching inhibitor factor will be described later). The present invention has been completed based on such novel findings and is an extremely epoch-making invention.

The present invention has the following configuration in order to solve the above problems.

(Composition 1)

A method for producing a transfer mask, which is a method for producing a transfer mask having a film on which a transfer pattern is formed on a substrate, wherein the film is made of a material that can be dry-etched; a preparation step of preparing a mask substrate on which a resist film is formed; an exposure step of exposing the transfer pattern to the resist film; and a developing step of the resist film after the exposure treatment Using etching The concentration of the barrier factor substance is higher than 0.3 ppb, and the developer having a pH of 8 or higher is subjected to development treatment; and the first rinsing step is performed by using the concentration of the etch barrier factor as 0.3 for the mask substrate after the development treatment. The first rinsing liquid having a pH of 8 or more is treated as ppb or less, and the second rinsing step is used after the first rinsing step, and the concentration of the etch inhibiting factor substance is 0.3 ppb or less, and the pH is lower than The 6th but not the 2nd lotion is processed.

(constituent 2)

In the method for producing a transfer mask according to the first aspect, the pH of the first rinse liquid is lower than the pH of the developer.

(constitution 3)

In the method for producing a transfer mask of the first or second aspect, the first rinse liquid adjusts the pH of the deionized water.

(construction 4)

The method for producing a transfer mask according to any one of the first to third aspects, wherein the second rinse liquid is deionized water.

(Constituent 5)

The method for producing a transfer mask according to any one of the first to fourth aspect, wherein the etch-stopping factor substance is bonded to other substances to cause an etching hindrance to the etching gas during the dry etching. Substance of matter.

(constituent 6)

The manufacturer of the transfer mask of any one of the components 1 to 5 The method wherein the etching inhibiting factor substance is at least one selected from the group consisting of calcium, magnesium, and aluminum.

(constituent 7)

In the method for producing a transfer mask according to any one of the first to sixth aspects, the etching inhibiting factor substance present in the developing solution is present in the liquid in an ionized state.

(Composition 8)

The method for producing a transfer mask according to any one of the first to seventh aspect, wherein the film is dry-etched by using an etching gas of at least one of a fluorine-based gas or a substantially oxygen-free chlorine-based gas. It can be made of an etchable material.

(constituent 9)

A method of producing a transfer mask according to any one of the first to eighth aspects, wherein the film is made of a ruthenium-containing material.

(construction 10)

The method for producing a transfer mask according to any one of the first to fifth aspect, wherein the film is formed by laminating a lower layer composed of a niobium-containing and nitrogen-containing material and a material containing niobium and oxygen from the substrate side. The upper layer of the multilayer film.

(Structure 11)

The method for producing a transfer mask according to any one of the first to tenth aspects, further comprising an etching step of dry etching the film on the mask substrate after the second rinsing step to form a transfer pattern .

(construction 12)

a manufacturing method of a mask for transfer 11, wherein the etcher The order is dry etching using an etching gas of at least one of a fluorine-based gas or a substantially chlorine-free gas.

According to the invention, it is possible to provide a method for producing a transfer mask which can suppress occurrence of black defects in the transfer mask.

Before the description of the method for producing the transfer mask of the present invention, the following experiment will be carried out to investigate the cause of the occurrence of the mask black defect.

In order to investigate the cause of the occurrence of a small black defect, two kinds of mask substrates were prepared. One type is a mask base on which a film made of a lanthanoid material is formed, and the other is a mask base on which a film made of a chrome-based material is formed.

A mask substrate on which a film composed of a lanthanoid material is formed is prepared as a binary mask substrate (hereinafter referred to as a lanthanide mask substrate, the mask of which is referred to as a lanthanide mask), which is provided on the light-transmitting substrate The light-shielding layer (film thickness: 42 nm) of TaN consisting essentially of niobium and nitrogen, and the laminated structure of the anti-reflection layer (film thickness: 9 nm) of TaO consisting essentially of yttrium and oxygen are comprised.

A mask substrate on which a film made of a chromium-based material is formed is prepared as a binary mask substrate (hereinafter referred to as a chromium-based mask substrate, the mask is referred to as a chromium-based mask), and is provided on the light-transmitting substrate. A light-shielding layer of a CrCON film (film thickness: 38.5 nm) consisting essentially of chromium and oxygen, nitrogen and carbon, and a CrON film (film thickness: 16.5 nm) consisting essentially of chromium and oxygen and nitrogen And consisting essentially of a laminated structure of chromium and oxygen, nitrogen and carbon (rCON antireflection layer (film thickness: 14 nm)).

The surface of the prepared 2 types of mask bases is respectively missing using a mask base A trap inspection device (M1350: manufactured by Lasertec) was used to perform defect inspection. As a result, defects such as particles or voids could not be confirmed on the surface of the film of any of the mask substrates.

Next, the transfer mask was produced using the two types of mask substrates. In the former, the ruthenium mask base is formed by masking the resist pattern formed on the surface of the mask substrate, and dry etching using a fluorine-based (CF ₄ ) gas is used to pattern the anti-reflection layer, and then, the reflection is performed. The protective layer was subjected to dry etching using a chlorine-based (Cl ₂ ) gas as a mask to pattern the light-shielding layer, and finally the resist pattern was removed to prepare a transfer mask.

In the latter, the chromium-based mask substrate is formed by using a resist pattern formed on the surface of the mask substrate as a mask, and dry etching using a mixed gas of a chlorine-based (Cl ₂ ) gas and an oxygen (O ₂ ) gas. The antireflection layer and the light shielding layer are patterned, and finally the resist pattern is removed to fabricate a transfer mask.

The two kinds of masks obtained were subjected to defect inspection by a mask defect inspection device (manufactured by KLA-Tencor Co., Ltd.). As a result, the lanthanide mask confirmed that there were many (more than 50) minute black defects. On the other hand, the chromium-based mask hardly confirmed the occurrence of minute black defects. In addition, the above-mentioned defects in the lanthanide mask are also confirmed in the case of performing UV treatment, ozone treatment or heating for the purpose of removing dirt on the mask substrate before forming the resist film.

In addition, the case where the anti-reflection layer and the light-shielding layer are patterned by dry etching using a fluorine-based (CF ₄ ) gas is also confirmed in the case of the minute black defect of the above-described enamel mask.

Scanning transmission electron microscope (STEM: Scanning Transmission Electron) for tiny black defects detected by defect inspection Microscope) section observation in bright field. In the cross-sectional observation, a platinum alloy is applied to the entire surface of the light-transmissive substrate on which the thin film pattern is formed.

As a result, it was confirmed that the micro black defect height was almost the same as the film thickness of the laminated film of the light shielding layer and the reflection preventing layer. Specifically, it was confirmed that the micro black defect is a laminated structure in which a material having a thickness of 5 to 10 nm is a surface oxide in a core having a size of about 23 nm and a height of about 43 nm (see FIG. 1).

Next, in order to investigate the cause of the occurrence of minute black defects in the transfer mask, the presence of the etching inhibitory factor substance on the surface of the mask substrate which was not detected during the defect inspection was investigated.

For this verification, two types of mask substrates (a lanthanide mask base and a chrome-based mask substrate) in which a resist film was temporarily formed on the surface of the film and the resist film was completely removed were prepared. Specifically, first, a positive resist film is formed on the film of the mask substrate by a spin coating method, and a baking treatment (drying treatment) after coating is performed. Next, the resist film is exposed to the entire surface (by which the resist film as a whole is soluble in the developer). Next, the mask substrate is subjected to development treatment to dissolve all the resist films, and rinsed with deionized water to remove the dissolved resist film from the surface of the film. Two types of mask substrates were prepared by the above steps.

The surface of the film (reflection preventing layer) of the two types of mask substrates subjected to the above treatment was analyzed by TOF-SIMS (Time-Of-Flight Secondary Ion Mass Spectrometry).

As a result, calcium which is an etch barrier factor substance is detected on the surface of the ruthenium mask base. On the other hand, the calcium on the surface of the chromium-based mask base is below the detection lower limit value.

Since the developer used in the resist film development step contains calcium (Ca ²⁺ ) as an impurity, the calcium detected by TOF-SIMS should be the calcium contained in the developer used this time.

From the result of the defect inspection of the transfer mask produced by using the above-described two kinds of mask substrates, and the analysis result of the surface of the mask base, it is presumed that the minute black defect of the transfer mask is as follows.

(1) The coating is formed on the surface of the mask substrate, and after exposure treatment, the resist film is exposed to the developer to be developed. At this time, the surface of the film exposed on the mask base due to the dissolution of the resist film by the developer strongly adheres to the calcium (Ca ²⁺ ) contained in the developer. Since the thickness of calcium (etching hindrance factor substance) is extremely thin, it is difficult to detect even with the latest mask substrate inspection apparatus (Fig. 2(a)).

(2) The reflection preventing layer (TaO) on the surface of the mask substrate is patterned by dry etching of a fluorine-based gas. At this time, the fluorine-based gas reacts with calcium adhering to the surface of the antireflection layer to form an etching inhibitor such as calcium fluoride (Fig. 2(b)). Since calcium fluoride has a high boiling point, it is difficult to be etched even if a fluorine-based gas is used, and thus it becomes an etching inhibitor. When the etching inhibitor is a mask, a portion of the anti-reflection layer (TaO) remains without being etched (Fig. 2(c)).

(3) The light shielding layer (TaN) is patterned by dry etching of a chlorine-based gas. At this time, since the etching rate of the chlorine-based gas of TaO is significantly smaller than that of TaN, the residual of the anti-reflection layer becomes a mask, and a part of the light-shielding layer (TaN) remains without being etched. Therefore, a core of minute black defects is formed (Fig. 3(d)).

(4) After that, the surface of the core of the minute black defect is oxidized, and an oxide layer is formed around the core, and a minute black defect is formed on the surface of the substrate (synthetic quartz glass) (Fig. 3(e)).

The mechanism of the occurrence of tiny black defects is described in terms of calcium. Magnesium, aluminum, and the like, which are the etching inhibitor substances to be described later, may react with fluorine or chlorine contained in the etching gas to form an etching inhibitor, and therefore, a micro black defect occurs in the same mechanism as described above. Further, when the etching inhibitor element such as calcium is dry-etched with a chlorine-based gas, it may react with the chlorine-based gas to form an etching inhibitor such as calcium chloride. The chloride of the etching inhibitor element such as calcium chloride has a high boiling point and is difficult to dry-etch, so it may become an etching inhibitor. In addition, in the above verification, in order to facilitate the analysis of the surface of the film of the mask substrate by TOF-SIMS, the entire surface of the resist film was exposed to be removed from the surface of the film. However, even in the case where the transfer pattern is exposed to the resist film to form a resist pattern as in the usual mask process, it is presumed that the surface of the film which is exposed by the dissolution of the resist still forms an etching inhibitor.

As described above, after the development treatment and the rinsing treatment of the resist film, calcium which is an etch-stopping factor substance is detected on the surface of the ruthenium-based mask substrate. On the other hand, the calcium on the surface of the chromium-based mask base is below the detection lower limit value. In the following, the reasons for such differences are examined. In addition, the following investigations are based on the estimation by the present inventors, and do not limit the scope of the present invention.

On the surface of the lanthanide mask substrate, a large number of hydroxyl groups (OH groups, which are attracted by hydrogen and oxygen) are present, and this hydroxyl group attracts calcium (Ca ²⁺ ) contained in the developer (Fig. 4(a)). Then, after the development treatment with the developer, the liquid covering the surface of the mask base is rapidly changed from alkaline (pH 10) to neutral (before and after pH 7) by rinsing with pure water for washing away the developer. Therefore, calcium (Ca ²⁺ ) attracted to the surface of the mask base becomes calcium hydroxide (Ca(OH) ₂ ) and is easily deposited on the surface of the film (Fig. 4(b)). This calcium hydroxide should be an etch stop factor substance on the surface of the mask substrate.

On the other hand, only a small number of hydroxyl groups (OH groups) exist on the surface of the chromium-based mask substrate. Therefore, the surface of the mask substrate does not attract the calcium (Ca ²⁺ ) contained in the developer. Since the concentration of the calcium contained in the original developer is low, the concentration of calcium (Ca ²⁺ ) near the surface of the film is extremely low (Fig. 5(a)). As a result, after development treatment with the developer, the calcium (Ca ²⁺ ) attracted to the surface of the mask base becomes calcium hydroxide (Ca) even when it is rinsed with pure water for washing away the developer. (OH) ₂ ) is washed away from the surface of the film, or it is only deposited as a small amount of calcium hydroxide which does not hinder the etching degree (Fig. 5(b)).

As described above, since the thickness of the etching inhibiting factor substance adhering to the surface of the film of the chromium-based mask base is thin, it is difficult to detect in the defect inspecting apparatus of the mask base. It is not impossible to scan the entire surface of the film with an atomic force microscope (AFM) to identify the substance to which the etch barrier factor is attached, but the detection requires a large amount of time. Therefore, in the same manner as described above, a film composed of a chromium-based material having a small amount of an etch-resistant factor substance adhered thereto is laminated in an amount of two layers at a film thickness of 100 nm, and is subjected to development treatment by a developing solution and rinsing by pure water. The treated lanthanide mask is on the film of the substrate. As a result, the bismuth-based material film has a part of the height of the etch-resistance factor, which is relatively high due to the so-called decorative effect, and can be detected by the defect inspection device of the mask base to protrude the defect.

Using this method, the etching inhibitory substance formed on the surface of the substrate of the enamel mask was observed in a dark field by a scanning transmission electron microscope (STEM: Scanning Transmission Electron Microscope) (see FIG. 6). Also, at this time, the energy diffusion X-ray attached to the STEM is used. Line detectors (EDX) also analyze the elements that make up the etch barrier factor. By EDX analysis, the portion on the surface of the ruthenium-based film in which the presence of the etch-blocking factor substance was confirmed (the portion indicated by the mark of Spot 1 in Fig. 6), and the etch-blocking factor substance as the control data were not confirmed. The portion on the surface of the chromium-based film (the portion indicated by the mark of Spot 2 in Fig. 6) is carried out. As a result, the detection intensity of Ca (calcium) and O (oxygen) is high at Spot 1, whereas the detection intensity of Ca (calcium) and O (oxygen) is extremely small at Spot 2. From the results of this analysis, it is presumed that a layer containing an etch-blocking factor substance is present at Spot 1.

The method for producing a transfer mask according to the embodiment of the present invention is as follows.

A method for producing a transfer mask, which is a method for producing a transfer mask having a film on which a transfer pattern is formed on a substrate, wherein the film is made of a material that can be dry-etched; a preparation step of preparing a mask substrate on which a resist film is formed; an exposure step of exposing the transfer pattern to the resist film; and a developing step of the resist film after the exposure treatment The development process is performed by using a developer having a pH higher than 0.3 ppb and having a pH of 8 or more, and a first rinse process using an etch barrier factor for the mask substrate after the development process. The concentration is below 0.3 ppb, and the pH is 8 The first rinsing liquid is treated as described above; and the second rinsing step is performed after the first rinsing step, wherein the concentration of the etch inhibiting factor substance is 0.3 ppb or less, and the pH is 6 or less but less than 8 The second lotion is processed

Here, the material that can be dry-etched is a material that can be dry-etched using a fluorine-based gas and a chlorine gas that is substantially free of oxygen, and specifically, tantalum (Ta), tungsten (W), and zirconium ( Zr), hafnium (Hf), vanadium (V), niobium (Nb), nickel (Ni), titanium (Ti), palladium (Pd), molybdenum (Mo), antimony (Si), and the like. Further, the material may contain oxygen, nitrogen, carbon, hydrogen, fluorine, or the like from the viewpoint of controlling optical characteristics or etching characteristics.

The film material on which the transfer pattern is formed is preferably a ruthenium-containing material. More preferably, a laminated film of tantalum nitride film (TaN) containing tantalum and nitrogen and tantalum oxide film (TaO) containing tantalum and oxygen is laminated. Here, the tantalum nitride film may be any material containing niobium and nitrogen, and may contain other elements in addition to niobium and nitrogen. Further, in the same manner as described above, the tantalum oxide film may contain other elements in addition to germanium and oxygen.

Further, the fluorine-based gas is exemplified by CHF ₃ , CF ₄ , SF ₆ , C ₂ F ₆ , C ₄ F ₈ or the like. The chlorine-based gas is exemplified by Cl ₂ , SiCl ₄ , CHCl ₃ , CH ₂ Cl ₂ , CCl ₄ or the like. Further, in addition to the fluorine-based gas or the chlorine-based gas, a dry gas may be a mixed gas of a gas such as He, H ₂ , Ar or C ₂ H ₄ .

Here, in the case where the fluorine-based gas or the substantially chlorine-free gas containing no oxygen is dry-etched as an etching gas, the ion main body tends to be dry-etched. In the case of dry etching of the ionic body, it is easy to control the anisotropic dry etching, and it has an excellent effect of improving the verticality of the side wall of the pattern formed by the film. However, in the case of anisotropic dry etching, due to the direction of the sidewall of the pattern Since etching is suppressed, when an etching-obstructing substance is provided on the film in which the resist pattern is not formed and the exposed portion is formed, it is difficult to remove by dry etching.

On the other hand, when the mixed gas of oxygen and a chlorine-based gas is dry-etched as an etching gas, the tendency of dry etching of the radical body is strong. In the case of dry etching of the radical body, it is difficult to control the anisotropic dry etching, and it is not easy to increase the sidewall verticality of the pattern formed by the film. However, in the case of the dry etching having such an isotropic tendency, since the etching in the direction of the sidewall of the pattern is also relatively easy, even if the film is formed on the exposed portion of the film in which the resist pattern is not formed, the etching is inhibited during the dry etching. It will also be easier to remove.

In the transfer mask according to the embodiment of the present invention which contains the lanthanide mask base, the film on which the transfer pattern is formed is formed by dry etching of the ionic body. Therefore, in the case of dry etching, an etch inhibiting factor substance is present on the surface of the film, and it is easy to cause minute black defects on the surface of the film. On the other hand, since the chromium-based film in the chromium-based mask substrate is formed by a material which can be dry-etched by a radical body, it can be said that even if an etching-inhibiting factor substance exists on the surface of the film, it is difficult to cause minute black in dry etching. defect.

Examples of the film on which the transfer pattern is formed include a light-shielding film having a function of shielding exposure light, and an anti-reflection film having a function of suppressing surface reflection in order to suppress multiple reflection with the transfer target, to improve the clarity of the pattern. A phase transfer film having a function of generating a predetermined transmittance and a predetermined phase difference with respect to exposure light. Further, an example in which a film having a transfer pattern is formed has a predetermined transmittance for exposure light, but also includes a semi-transparent film having a phase difference which does not cause a phase shift effect. The mask base with such a semi-transmissive film is mainly Used for Enhancer type phase shift masks. The films may be a single layer film or a laminated film in which the films are laminated in multiple layers. Further, a transfer mask having a film forming the transfer pattern is provided, and ArF excimer laser light or KrF excimer laser light or the like is applied to the exposure light.

The transfer mask may be a pass-through type mask as described above or a reflective type mask.

Further, the mask substrate for fabricating the transfer mask may be a mask substrate for forming a transmissive mask, or may be a mask substrate for forming a reflective mask (hereinafter, The mask substrate forming the reflective mask is referred to as a reflective mask substrate).

In the reflective mask, examples of the film on which the transfer pattern is formed include an absorber film having a function of absorbing exposure light, a reflection reducing film for reducing reflection of exposure light, and a patterning of the absorber film. A barrier layer or the like for preventing etch damage to the multiple reflection film.

Further, the film constituting the mask base for forming the upper transfer mask may be provided as an etching mask (hard mask) function in addition to the film which is the transfer pattern, when the film of the lower layer is etched. Mask film (or hard mask film). Alternatively, an etching mask (hard mask) may be provided to form a film which becomes a transfer pattern as a laminated film and become a part of the laminated film.

Further, in the case where the substrate is in the transmissive type mask, it may be any material that allows the exposure light to penetrate, and for example, synthetic quartz glass is exemplified. In the case of the reflective type mask substrate, any material which can prevent thermal expansion due to absorption of the exposure light can be used, and examples thereof include TiO ₂ -SiO ₂ low expansion glass, crystallized glass which precipitates β quartz solid solution, and single crystal. Crystal germanium, SiC, etc. Further, it is preferable that the substrate in the reflective mask has a multilayer reflective film substrate having a multilayer reflective film (Mo/Si multilayer reflective film) for reflecting the exposure light on the substrate.

Further, the resist film can be applied to either a positive type or a negative type, and any of the effects can be obtained by the present invention. The resist film can be formed by any one of a resist for laser light exposure and a resist for electron beam drawing exposure. Since the exposure fine pattern can be drawn, the resist film is preferably formed by a resist for electron beam drawing exposure. In particular, the resist film is preferably formed by a chemically amplified resist.

Further, the exposure treatment for exposing the transfer pattern to the resist film differs depending on the resist, but the drawing exposure using the electron beam drawing exposure apparatus and the drawing exposure using the laser drawing exposure apparatus can be applied. In particular, the drawing exposure of the electron beam drawing exposure apparatus is preferable because a very fine transfer pattern can be exposed to the resist film.

In the method for producing a mask for transfer printing in the embodiment of the present invention, in addition to the preparation step of preparing the mask substrate and the exposure step of exposing the transfer pattern to the resist film, the development step and the first rinse step are included. And a second rinse process (see Fig. 7). Hereinafter, each of these steps will be described.

[Development process]

In the development step, a resist film having a transfer pattern for exposure treatment is used, and a development process is performed using a developer having a higher concentration of the etching inhibitor factor than 0.3 ppb and having a pH of 8 or more.

As the developer, a developer solution can be used, but an alkaline aqueous solution of an organochlorine-based compound such as TMAH (tetramethylammonium hydroxide), choline (2-hydroxyethyltrimethylamine), monoethanolamine is preferably used. An aqueous solution.

As the developing method, a known method such as Dip development, spray development, or Paddle development can be used.

The etching inhibitor element means a material which reacts with fluorine (F) or chlorine (Cl) contained in the dry etching gas to form an etching inhibitor.

Specifically, the etching inhibitor factor is, for example, calcium (Ca), magnesium (Mg), aluminum (Al), or the like, and is a substance which dissolves as an ion in a developing solution (alkaline solution). can.

When the etching inhibitor element is Ca or Mg, when the film is dry-etched with a fluorine-based gas or a chlorine-based gas, calcium fluoride (boiling point: 2500 ° C) and magnesium fluoride (boiling point: 2260 ° C) are formed. Compounds such as calcium chloride (boiling point 1600 ° C) and magnesium chloride (boiling point 1412 ° C), these compounds become etch inhibiting substances.

The concentration of the etching inhibitor factor contained in the developer is set to be higher than 0.3 ppb (mass ratio). Since the developing solution inevitably contains an etching inhibitor substance such as calcium (Ca ²⁺ ) in the process, the concentration of the etching inhibiting factor substance contained in the developing solution is higher than 0.3 ppb.

The developer used in the development step is pH 8 or higher, preferably pH 9 or higher, more preferably pH 10 or higher, and is alkaline.

[First rinsing process]

After the development process, the first rinse process is performed. The first rinsing step is a step of performing a rinsing treatment on the mask substrate after the development treatment using a first rinsing liquid having a concentration of an etch inhibiting factor of 0.3 ppb or less and a pH of 8 or more.

For the first rinse liquid, for example, an aqueous ammonia solution prepared by dissolving ammonia (NH ₃ ) in DI water (deionized water) can be used.

In the rinsing treatment method, the first rinsing liquid can be used while the first rinsing liquid is supplied onto the rotating substrate while the surface rinsing is performed. Any method such as a Dip method in which a substrate is immersed in a bath to perform surface rinsing.

The concentration of the etching inhibiting factor substance contained in the first rinse liquid is 0.3 ppb (mass ratio) or less, preferably 0.1 ppb or less, more preferably 0.05 ppb or less.

When the concentration of the etching inhibitor element contained in the first rinse liquid exceeds 0.3 ppb, the number of minute black defects having a size of 20 to 100 nm generated on the surface of the transfer mask is increased. In fact, defect correction becomes difficult.

The first rinse liquid has a pH of 8 or higher, preferably pH 9 or higher, more preferably pH 10 or higher, and is alkaline.

The first rinse liquid preferably has a lower pH than the developer used in the development step.

[Second rinse process]

After the first rinse process, the second rinse process is performed. In the second rinsing step, the mask base after the first rinsing step is rinsing treatment using a second rinsing liquid having a concentration of an etch inhibiting factor of 0.3 ppb or less and a pH of 6 or less but less than 8. Process.

As the second rinse liquid, for example, neutral pure water such as DI water (deionized water) can be used.

In the rinsing treatment method, the surface rinsing can be performed by immersing the substrate in a tank in which the second rinsing liquid is accumulated while the second rinsing liquid is supplied onto the rotating substrate while performing surface rinsing. Any method such as Dip mode.

The concentration of the etch inhibitor factor contained in the second rinse solution is 0.3 ppb (mass ratio) or less, preferably 0.1 ppb or less, more preferably 0.05 ppb or less.

When the concentration of the etching inhibitor element contained in the second rinse liquid exceeds 0.3 ppb, when the transfer mask is produced, the number of minute black defects having a size of 20 to 100 nm generated on the surface thereof increases. In fact, defect correction becomes difficult.

The pH of the second rinse is 6 but less than 8, preferably 6.5 but less than 7.5, and is almost neutral.

The second rinse preferably has a lower pH than the first rinse.

Further, the concentration of the etching inhibiting factor substance contained in the developer, the first rinse liquid, and the second rinse liquid means inductive coupling by the developer or the rinse liquid before being supplied to the surface of the mask substrate. The total concentration of the elements detected by the analysis method (except for the elements below the detection limit) is measured by ICP-MS (Inductively Coupled Plasma-Mass Spectroscopy).

The resist pattern (transfer pattern) can be formed on the resist film by the development process, the first rinse process, and the second rinse process. A transfer mask can be produced by using a mask substrate on which the resist pattern is formed.

Specifically, the resist pattern is used as a mask, and the anti-reflection layer is patterned by dry etching using a fluorine-based (CF ₄ ) gas. Thereafter, the anti-reflection layer is used as a mask, and a chlorine-based (Cl) is used. ₂ ) Dry etching of the gas to pattern the light shielding layer, and finally removing the resist pattern, thereby producing a transfer mask.

The transfer mask thus obtained is significantly smaller in number than the transfer mask produced by using the conventional mask substrate. The reason is related to the cause of the occurrence of the minute black defect described above. That is, in order to sequentially treat the surface of the mask substrate with a developer (alkaline)→first moisturizing liquid (alkaline)→second moisturizing liquid (neutral), the pH change of the surface of the mask may change. It is moderated, and calcium ions (Ca ²⁺ ) attracted to the surface of the mask base may hardly become calcium hydroxide (Ca(OH) ₂ ). As a result, the surface of the mask substrate should be difficult to adhere to calcium hydroxide (Ca(OH) ₂ ) which is an etch barrier substance.

The reason why the etching inhibiting factor substance adheres to the film of the mask substrate may also occur in processes other than the above. Prior to forming the resist on the film of the mask substrate, the surface of the film is typically treated with a treatment fluid (e.g., a cleaning solution). The treatment liquid is alkaline, and further, the treatment liquid still contains an etch inhibiting factor substance. Further, after the surface of the film is treated with the alkaline treatment liquid, it is washed with a lotion liquid in a neutral region. Therefore, after the development process of the resist film, the same phenomenon as in the case where the rinsing process is performed by the rinsing liquid in the past is caused, and the phenomenon that the etch inhibiting factor substance adheres to the surface of the film of the mask base easily occurs. The inventors of the present invention have found that a solution to the technical problem of development processing of the resist film can be applied to the problem of the related art of treating the film of the mask substrate with the treatment liquid, and the second invention is conceived. Invention relating to a method of manufacturing a cover substrate. The second invention specifically has the following configuration.

(Composition 1A)

A method for manufacturing a mask substrate, comprising: a method for manufacturing a mask substrate having a film for forming a transfer pattern on a substrate, wherein the film is made of a material that can be dry etched; The first treatment step is performed by using a first treatment liquid having a pH of 8 or more for the surface of the film to be higher than 0.3 ppb, and a second treatment step for the second treatment step. After the first treatment step, the surface treatment is performed using the second treatment liquid having a concentration of the etching inhibitor factor of 0.3 ppb or less and having a pH of 8 or more, and the third treatment step is performed by etching after the second treatment step. The third treatment liquid having a concentration of the barrier factor substance of 0.3 ppb or less and having a pH of 6 or less but less than 8 is subjected to surface treatment.

(constitution 2A)

The method for producing a mask substrate according to 1A, wherein the pH of the second treatment liquid is lower than the pH of the first treatment liquid.

(constitution 3A)

A method for producing a mask substrate comprising 1A or 2A, wherein the first treatment liquid contains a cleaning solution of a surfactant.

(constitution 4A)

The method for producing a mask substrate according to any one of the components 1A to 3A, wherein the second treatment liquid is a rinse liquid which does not contain a surfactant.

(constitution 5A)

A method of producing a mask substrate according to any one of 1A to 4A, wherein the third treatment liquid is deionized water.

(Constitute 6A)

The manufacturing side of the mask substrate constituting any one of 1A to 5A The method wherein the etch inhibiting factor substance is bonded to other substances to form an etch inhibiting substance resistant to the etching gas during the dry etching.

(Constitute 7A)

The method for producing a mask substrate according to any one of the above 1A to 6A, wherein the etching inhibiting factor substance is at least one selected from the group consisting of calcium, magnesium, and aluminum.

(Composition 8A)

The method for producing a mask substrate according to any one of the above 1A to 7A, wherein the etching inhibiting factor substance present in the first processing liquid is present in the liquid in an ionized state.

(Composition 9A)

The method for producing a mask substrate according to any one of the components 1A to 8A, wherein the film is etched by dry etching using an etching gas of at least one of a fluorine-based gas or a substantially oxygen-free chlorine-based gas. Made up of materials.

(constitution 10A)

A method of producing a mask substrate according to any one of 1A to 9A, wherein the film is composed of a ruthenium-containing material.

(Composition 11A)

A method of manufacturing a mask substrate according to any one of 1A to 10A, wherein the film is formed by laminating a lower layer composed of a niobium-containing and nitrogen-containing material and an upper layer composed of a niobium-containing and oxygen-containing material from the substrate side. Multilayer film.

(Composition 12A)

A transfer mask is obtained by using a mask substrate manufactured by a manufacturing method of a mask substrate constituting any one of 1A to 11A, and forming a transfer pattern by dry etching.

According to the second aspect of the invention, there is provided a method of manufacturing a mask substrate, which can suppress occurrence of black defects in the mask for transfer. In addition, in the method of manufacturing the mask substrate, the configuration of the mask substrate or the configuration of the transfer mask manufactured from the mask substrate, the matters relating to the film material, the matters concerning the substrate, and the etching The matter of the gas is the same as in the case of the manufacturing method of the transfer mask.

The method for producing a mask base according to the second aspect of the invention includes the first treatment step, the second treatment step, and the third treatment step. Hereinafter, each of these steps will be described.

[First Processing Step]

The first treatment step is a step of performing surface treatment on the surface of the film formed on the mask base by using a first treatment liquid having a concentration of an etching inhibitor factor higher than 0.3 ppb and having a pH of 8 or more.

Examples of the first treatment liquid include a cleaning liquid used for the purpose of removing foreign matter (particles) adhering to the surface of the mask base or foreign matter (particles) mixed in a film to be a transfer pattern. Further, in the case where the film to be transferred is formed of a material having a low adhesion to the resist film (particularly, a Si-containing material), in order to prevent peeling or collapse of the fine pattern formed by the resist film, A surface treatment liquid (for example, hexamethyldioxane (HMDS)) for reducing the surface energy of the surface of the mask substrate, or a surface treatment agent with other organic lanthanum for alkaneization of the surface of the mask substrate ( A surface treatment solution of alkylsilyl). Surface treatment In the method, one of the Dip method in which the surface of the first rinse liquid is supplied to the rotating substrate and the substrate is immersed in the groove in which the first rinse liquid is accumulated to perform surface treatment can be used. method.

The etching inhibitor element means a material which reacts with fluorine (F) or chlorine (Cl) contained in the dry etching gas to form an etching inhibitor.

Specifically, the etching inhibitor factor is, for example, calcium (Ca), magnesium (Mg), aluminum (Al), or the like, and is dissolved as long as it is an ion in the first treatment liquid (alkaline solution). The substance can be.

When the etching inhibitor element is Ca or Mg, when the film is dry-etched with a fluorine-based gas or a chlorine-based gas, calcium fluoride (boiling point: 2500 ° C) and magnesium fluoride (boiling point: 2260 ° C) are formed. Compounds such as calcium chloride (boiling point 1600 ° C) and magnesium chloride (boiling point 1412 ° C), these compounds become etch inhibiting substances.

The concentration of the etching inhibitor factor contained in the first treatment liquid is set to be higher than 0.3 ppb (mass ratio).

When the first treatment liquid is a cleaning liquid, the cleaning liquid contains a surfactant. Since the surfactant inevitably contains an etching inhibitor factor such as calcium (Ca ²⁺ ), the concentration of the etching inhibitor factor contained in the first treatment liquid is higher than 0.3 ppb.

The first treatment liquid is pH 8 or higher, preferably pH 9 or higher, more preferably pH 10 or higher, and is alkaline.

[Second treatment process]

After the first treatment step, the second treatment step is performed. The second treatment step is performed on the surface of the film formed on the mask base, and the second treatment liquid having a concentration of the etching inhibitor factor of 0.3 ppb or less and a pH of 8 or more is used. To carry out the surface treatment process.

The second treatment liquid is preferably a cleaning liquid which does not contain a surfactant. As the second treatment liquid, for example, an aqueous ammonia solution prepared by dissolving ammonia (NH ₃ ) in DI water (deionized water) can be used.

In the method of the surface treatment, a method of performing surface treatment while supplying the second treatment liquid onto the rotating substrate, and a Dip method of immersing the substrate in a tank in which the second treatment liquid is stored and performing surface treatment may be used. A method.

The concentration of the etching inhibitor element contained in the second treatment liquid is 0.3 ppb (mass ratio) or less, preferably 0.1 ppb or less, more preferably 0.05 ppb or less.

When the concentration of the etching inhibitor element contained in the second treatment liquid exceeds 0.3 ppb, the number of minute black defects having a size of 20 to 100 nm generated on the surface of the mask is increased, so that the defect is actually corrected. It has become difficult.

The second treatment liquid is pH 8 or higher, preferably pH 9 or higher, more preferably pH 10 or higher, and is alkaline.

The second treatment liquid preferably has a lower pH than the first treatment liquid. In other words, it is preferable that the pH of the second treatment liquid is lower than the pH of the first treatment liquid, and the difference from the pH of the third treatment liquid is reduced in advance. By this means, after the treatment of the second treatment liquid, even if a large amount of etch-resistance factor in the ion state remains in the vicinity of the surface of the film, it is possible to prevent the remaining etch-resistance factor from being deposited as a hydroxide.

[Third processing step]

After the second treatment step, the third treatment step is performed. The third treatment step is a step of performing a surface treatment on the surface of the film formed on the mask base by using a third treatment liquid having a concentration of the etching inhibitor factor of 0.3 ppb or less and a pH of 6 or less but less than 8.

As the third treatment liquid, for example, pure water such as DI water (deionized water) can be used.

In the method of the surface treatment, a method of performing surface treatment while supplying the third treatment liquid onto the rotating substrate, a Dip method in which the substrate is immersed in a tank in which the third treatment liquid is stored, and surface treatment may be used. One method

The concentration of the etching inhibiting factor substance contained in the third processing liquid is 0.3 ppb (mass ratio) or less, preferably 0.1 ppb or less, more preferably 0.05 ppb or less. When the concentration of the etching inhibiting factor substance contained in the third processing liquid exceeds 0.3 ppb, the number of minute black defects having a size of 20 to 100 nm generated on the surface of the mask is increased, so that the defect correction is actually caused. It has become difficult.

The pH of the third treatment liquid is larger than 6 but less than 8, preferably 6.5 but less than 7.5, and is almost neutral.

The third treatment liquid preferably has a lower pH than the second treatment liquid.

In addition, the concentration of the etching inhibitor factor contained in the first to third processing liquids refers to inductively coupled plasma mass spectrometry (ICP-MS: Inductively Coupled) by the treatment liquid supplied to the surface of the mask substrate. Plasma-Mass Spectroscopy) The total concentration of the elements detected by the analysis method (except for the elements below the detection limit).

After the surface treatment of the mask base is performed by the above-described first to third processing steps, the mask for the transfer can be produced using the mask substrate. Specifically, a resist pattern is formed on the surface of the mask substrate, and the resist pattern is used as a mask, and dry etching using a fluorine-based (CF ₄ ) gas is used to pattern the anti-reflection layer, and then the anti-reflection layer is formed. As a mask, dry etching using a chlorine-based (Cl ₂ ) gas is used to pattern the light-shielding layer, and finally, the resist pattern is removed, and a transfer mask can be produced.

The transfer mask thus obtained is significantly smaller in number than the transfer mask produced by using the conventional mask substrate. The reason is related to the cause of the occurrence of the minute black defect described above. That is, in order to wash the surface of the mask base in the first treatment liquid (alkaline) → the second treatment liquid (alkaline) → the third treatment liquid (neutral), the pH of the surface of the substrate is changed. It becomes gentle, and calcium ions (Ca ²⁺ ) attracted to the surface of the mask base hardly become calcium hydroxide (Ca(OH) ₂ ). As a result, the surface of the mask substrate should be difficult to adhere to calcium hydroxide (Ca(OH) ₂ ) which is an etch barrier substance.

Next, a method of manufacturing the transfer mask of the present invention will be described using an embodiment.

(Example 1)

The mask substrate used in this embodiment is a plurality of binary mask substrates for ArF excimer laser exposure corresponding to a semiconductor design rule DRAM with a half pitch of 32 nm. The mask base is formed on a synthetic quartz glass substrate having a size of about 152 mm × about 152 mm to form a light-shielding layer (film thickness: 42 nm) of TaN substantially composed of niobium and nitrogen, and TaO consisting essentially of niobium and oxygen. The film formed by the laminated structure of the antireflection layer (film thickness: 9 nm).

The developer used in the development step is prepared with the following developer.

Developer A: TMAH (calcium concentration 3.0 ppb, pH 10.0)

Developer B: Choline (calcium concentration 3.0 ppb, pH 10.0)

The first rinse liquid is prepared by the following rinse liquid.

Lotion C: DI water containing ammonia (calcium concentration 0.3ppb, pH10.0)

Lotion D: DI water containing ammonia (calcium concentration 0.3ppb, pH 9.0)

Lotion E: DI water containing ammonia (calcium concentration 0.1ppb, pH10.0)

Lotion F: DI water containing ammonia (calcium concentration 0.1ppb, pH 9.0)

The second rinse liquid is prepared by the following rinse liquid.

Lotion G: DI water (calcium concentration 0.3ppb, pH7.0)

Lotion H: DI water (calcium concentration 0.1ppb, pH7.0)

First, a positive-type electron beam drawing exposure chemical amplification type resist (PRL009: manufactured by FUJIFILM Electronic Materials Co., Ltd.) was applied to the surface of the mask substrate by a spin coating method, and then pre-baked to form a resist film (preparation step).

Next, an exposure process (exposure process) of the desired transfer pattern is performed on the resist film using an electron beam drawing device. In addition, the pattern after electron beam drawing is used to divide the fine pattern of the DRAM half-pitch (hp) 32 nm generation into one of the two relatively loose transfer patterns using a double patterning technique.

Next, in the liquid tank in which the developer A or the developer B is accumulated, the mask substrate on which the resist film is formed is immersed to develop the resist film (developing step).

Next, using any of the rinsing liquids C to F, the rinsing treatment of the mask base after the development treatment is performed. In addition, the rinsing treatment of the mask substrate is performed by The rotation method is performed (the first rinse process).

Next, the rinsing treatment of the mask base after the first rinsing step is performed using the rinsing liquid G or the rinsing liquid H. Further, the rinsing treatment of the mask base is performed by a rotation method (second rinsing step).

Then, the resist pattern (transfer pattern) formed by each of the above-described processes is used as a mask, and dry etching using a fluorine-based (CF ₄ ) gas is performed to pattern the anti-reflection layer to form an anti-reflection layer pattern. Thereafter, dry etching using a chlorine-based (Cl ₂ ) gas is performed, and the light-shielding layer is patterned by using the anti-reflection layer pattern as a mask to form a light-shielding layer pattern. Finally, the resist pattern is removed to produce a transfer mask.

The mask for the transfer was obtained, and the defect inspection was performed in the transfer pattern formation region (132 mm × 104 mm) using a mask defect inspection device (manufactured by KLA-Tencor Co., Ltd.), and the number of minute black defects of 100 nm or less was obtained. 50 or less, the defect correction burden is less good.

(Example 2)

In Embodiment 2, the mask substrate is a reflective mask substrate for making a reflective mask used for EUV lithography, which uses extremely short ultraviolet (Extreme UltraViolet, EUV wavelength about 13 nm) light. . In the second embodiment, a reflective mask was produced in the same manner as in the first embodiment except that a reflective mask substrate was used.

This reflection-type mask substrate are substrates used in low expansion glass substrate on TiO ₂ -SiO _2, the formation of a useful multilayer reflective layer to the reflection of EUV light at a high reflectance (the Mo and Si alternately stacking 40 periods, Finally, a Mo/Si multilayer reflective film in which Si is laminated) and a protective layer (Ru film) which exhibits an etching stop function when etched into an absorber film of a transfer pattern. An absorber film as a film to be a transfer pattern is formed on the substrate. This absorber film layer has a two-layer structure in which an absorber layer using a material having high absorbability to EUV light and an antireflection layer using a material having low reflectance for inspection light are laminated. The absorber layer is a TaBN film which is substantially dry-etched by an ionic body and consists essentially of lanthanum and boron and nitrogen. The antireflection layer is a TaBO film which is substantially dry-etched by an ionic body and consists essentially of lanthanum and boron and oxygen.

First, a positive-type chemical amplification type resist (PRL009: manufactured by FUJIFILM Electronic Materials Co., Ltd.) was applied onto the surface of a reflective mask substrate by spin coating, and then pre-baked to form a resist film (preparation step).

Next, an exposure process (exposure process) of the desired transfer pattern (a fine pattern of a DRAM half pitch (hp) 32 nm generation) was performed on the resist film using an electron beam drawing device.

Next, in the liquid tank in which the developer A or the developer B is accumulated, the reflective mask substrate on which the resist film is formed is immersed to develop the resist film (developing step).

Next, using any of the rinsing liquids C to F, the rinsing treatment of the reflective mask base after the development treatment is performed. Further, the rinsing treatment of the reflective mask base is performed by a rotation method (first rinsing step).

Next, the rinsing treatment of the reflective mask base after the first rinsing step is performed using the rinsing liquid G or the rinsing liquid H. Further, the rinsing treatment of the reflective mask base is performed by a rotation method (second rinsing step).

Next, a resist pattern (transfer pattern) formed by development processing is used as a mask, and dry etching using a fluorine-based (CF ₄ ) gas is performed to pattern the anti-reflection layer to form an anti-reflection layer pattern. Thereafter, dry etching using a chlorine-based (Cl ₂ ) gas is performed, and the absorber layer is patterned by using the anti-reflection layer pattern as a mask to form an absorber layer pattern. Finally, the resist pattern is removed to produce a transfer mask (reflective mask).

The mask for the transfer (reflective type mask) obtained was subjected to defect inspection in a transfer pattern forming region (132 mm × 104 mm) using a mask defect inspection device (manufactured by KLA-Tencor Co., Ltd.) to obtain a fineness of 100 nm or less. The number of black defects is 50 or less, and the defect correction burden is small.

Next, a method of manufacturing the mask base according to the second invention will be described using an embodiment.

(Example 3)

The mask substrate used in this embodiment 3 is a plurality of binary mask substrates for ArF excimer laser exposure corresponding to a semiconductor design rule DRAM with a half pitch of 32 nm. The mask base is formed on a synthetic quartz glass substrate having a size of about 152 mm × about 152 mm to form a light-shielding layer (film thickness: 42 nm) of TaN substantially composed of niobium and nitrogen, and TaO consisting essentially of niobium and oxygen. The film formed by the laminated structure of the antireflection layer (film thickness: 9 nm).

The first treatment liquid was prepared with the following washing liquid.

Cleaning solution A2: surfactant-containing cleaning solution (calcium concentration 1.0ppb, pH10.0)

Cleaning solution B2: Containing surfactant cleaning solution (calcium concentration 0.5ppb, pH10.0)

The second treatment liquid was prepared by the following rinse liquid.

Lotion C2: DI water + ammonia (calcium concentration 0.3ppb, pH10.0)

Lotion D2: DI water + ammonia (calcium concentration 0.3ppb, pH 9.0)

Lotion E2: DI water + ammonia (calcium concentration 0.1ppb, pH10.0)

Lotion F2: DI water + ammonia (calcium concentration 0.1ppb, pH 9.0)

The third treatment liquid was prepared by the following rinse liquid.

Washing solution G2: DI water (calcium concentration 0.3ppb, pH7.0)

Lotion H2: DI water (calcium concentration 0.1ppb, pH7.0)

First, the cleaning of the above-mentioned mask base is performed using the cleaning liquid A2 or the cleaning liquid B2. Further, the cleaning of the mask base is performed by spin cleaning (first processing step).

Next, the mask base is rinsed and washed using any of the rinse liquids C2 to F2. Further, the cleaning of the mask base is performed by spin cleaning (second treatment step).

Finally, the pure water rinse of the above-mentioned mask base is washed using the rinse liquid G2 or the rinse liquid H2. Further, the cleaning of the mask base is performed by spin cleaning (third processing step).

After the surface of the mask substrate after the cleaning treatment, a positive-type chemical amplification type resist (PRL009: manufactured by FUJIFILM Electronic Materials Co., Ltd.) was applied by spin coating, and then pre-baked to form a resist film. Next, the resist film was drawn, developed, and washed to form a resist pattern on the surface of the mask substrate. Next, the resist pattern is used as a mask, and dry etching using a fluorine-based (CF ₄ ) gas is performed to pattern the anti-reflection layer to form an anti-reflection layer pattern. Thereafter, dry etching using a chlorine-based (Cl ₂ ) gas is performed, and the light-shielding layer is patterned by using the anti-reflection layer pattern as a mask to form a light-shielding layer pattern. Finally, the resist pattern is removed to produce a transfer mask.

A mask defect inspection device (manufactured by KLA-Tencor Co., Ltd.) was used in the transfer pattern forming region (132 mm × 104 mm) for the transfer mask obtained. The defect inspection was carried out, and the number of the minute black defects of 100 nm or less was 50 or less, and the defect correction burden was small.

(Example 4)

The mask substrate of Example 4 used a reflective mask substrate for making a reflective mask used for EUV lithography using Extreme UltraViolet (EUV wavelength: about 13 nm) light. In the fourth embodiment, a mask was produced in the same manner as in the third embodiment except that the reflective mask substrate was used.

This reflection-type mask substrate are substrates used in low expansion glass substrate on TiO ₂ -SiO _2, the formation of a useful multilayer reflective layer to the reflection of EUV light at a high reflectance (the Mo and Si alternately stacking 40 periods, Finally, a Mo/Si multilayer reflective film in which Si is laminated) and a protective layer (Ru film) which exhibits an etching stop function when etched into an absorber film of a transfer pattern. An absorber film as a film to be a transfer pattern is formed on the substrate. This absorber film layer has a two-layer structure in which an absorber layer using a material having high absorbability to EUV light and an antireflection layer using a material having low reflectance for inspection light are laminated. The absorber layer is a TaBN film which is substantially dry-etched by an ionic body and consists essentially of lanthanum and boron and nitrogen. The antireflection layer is a TaBO film which is substantially dry-etched by an ionic body and consists essentially of lanthanum and boron and oxygen.

First, the cleaning of the reflective mask base is performed using the cleaning liquid A2 or the cleaning liquid B2. Further, the cleaning of the reflective mask base is performed by spin cleaning (first processing step).

Next, using any of the rinse liquids C2 to F2, the reflective mask base is rinsed and washed. Further, the cleaning of the reflective mask base is performed by spin cleaning (second processing step).

Finally, using the rinse liquid G2 or the rinse liquid H2, the pure water rinse of the reflective mask base is washed. Further, the cleaning of the reflective mask base is performed by spin cleaning (third processing step).

After the surface of the reflective mask substrate after the cleaning treatment, a positive-type chemical amplification type resist (PRL009: manufactured by FUJIFILM Electronic Materials Co., Ltd.) was applied by spin coating, and then pre-baked to form a resist film. Next, the resist film was drawn, developed, and washed to form a resist pattern on the surface of the reflective mask substrate. Next, the resist pattern is used as a mask, and dry etching using a fluorine-based (CF ₄ ) gas is performed to pattern the anti-reflection layer to form an anti-reflection layer pattern. Thereafter, dry etching using a chlorine-based (Cl ₂ ) gas is performed, and the anti-reflection layer pattern is used as a mask to pattern the absorber layer to form an absorber film pattern composed of the laminated absorber layer pattern and the anti-reflection layer pattern. . Finally, the resist pattern is removed to produce a transfer mask (reflective mask).

The mask for the transfer (reflective type mask) obtained was subjected to defect inspection in a transfer pattern forming region (132 mm × 104 mm) using a mask defect inspection device (manufactured by KLA-Tencor Co., Ltd.) to obtain a fineness of 100 nm or less. The number of black defects is 50 or less, and the defect correction burden is small.

Fig. 1 is a cross-sectional photograph of a micro black defect observed by a scanning type transmission electron microscope in a bright field.

Fig. 2 is a diagram for explaining the first half (a) to (c) of the mechanism of occurrence of minute black defects.

Fig. 3 is a view for explaining the latter half (d) to (e) of the mechanism of occurrence of minute black defects.

Fig. 4 is an explanatory view showing a mechanism of attaching an etch barrier substance to the surface of the lanthanide mask substrate.

Fig. 5 is an explanatory view showing a mechanism in which an etch barrier factor substance is adhered to the surface of a chromium-based mask substrate.

Fig. 6 is a cross-sectional photograph of an etch barrier factor substance formed on the surface of a lanthanide mask substrate by a scanning type transmission electron microscope in a dark field.

Fig. 7 is a flow chart showing a method of manufacturing a mask for transfer.

Claims (12)

A method for producing a transfer mask, which is a method for producing a transfer mask having a film on which a transfer pattern is formed on a substrate, wherein the film is made of a material that can be dry-etched; a preparation step of preparing a mask substrate on which a resist film is formed; an exposure step of exposing the transfer pattern to the resist film; and a developing step of the resist film after the exposure treatment The development process is performed by using a developer having a pH higher than 0.3 ppb and having a pH of 8 or more, and a first rinse process using an etch barrier factor for the mask substrate after the development process. The first rinsing liquid having a concentration of 0.3 ppb or less and having a pH of 8 or more is treated; and the second rinsing step is performed after the first rinsing step, and the concentration of the etch inhibiting factor substance is 0.3 ppb or less. The second rinse solution having a pH greater than 6 but not reaching 8 is treated. The method for producing a transfer mask according to claim 1, wherein the pH of the first rinse solution is lower than the pH of the developer. The method for producing a transfer mask according to the first aspect of the invention, wherein the first rinse liquid adjusts the pH of the deionized water. The method for producing a transfer mask according to the first aspect of the invention, wherein the second rinse liquid is deionized water. The method for producing a transfer mask according to the first aspect of the invention, wherein the etch-stopping factor substance is bonded to other substances to form an etch-resistant substance resistant to the etching gas during the dry etching. . The method for producing a transfer mask according to the first aspect of the invention, wherein the etching inhibiting factor substance is at least one selected from the group consisting of calcium, magnesium, and aluminum. The method for producing a transfer mask according to claim 1, wherein the etching inhibiting factor substance present in the developing solution is present in the liquid in an ionized state. The method for producing a transfer mask according to the first aspect of the invention, wherein the film is an etchable material which is dry-etched using an etching gas of at least one of a fluorine-based gas or a substantially oxygen-free chlorine-based gas. . The method for producing a transfer mask according to the first aspect of the invention, wherein the film is composed of a ruthenium-containing material. The method for producing a transfer mask according to the first aspect of the invention, wherein the film is formed by laminating a lower layer composed of a niobium-containing and nitrogen-containing material and an upper layer composed of a niobium-containing and oxygen-containing material. membrane. The method for producing a transfer mask according to any one of claims 1 to 10, further comprising an etching step of dry etching the film on the mask substrate after the second rinsing step Transfer pattern. The method for producing a transfer mask according to claim 11, wherein the etching step is dry etching using an etching gas of at least one of a fluorine-based gas or a substantially oxygen-free chlorine-based gas.