KR20220060515A - Method of manufacturing transfer mask and developer - Google Patents

Abstract

Provided is a technology for forming a resist pattern with a straight pattern edge while reducing resist pattern swelling, pattern collapse and resist pattern distortion. A manufacturing method of a transfer mask according to the present invention comprises the steps of: preparing a substrate having a thin film; forming a resist film on a surface of the thin film; exposing the resist film to light; forming the resist pattern by developing the resist film after the step of exposing; and etching the thin film using the resist pattern as a mask. In the step of forming the resist pattern, the resist film is formed by a chemically amplified negative-type resist liquid, and a developing solution used in the step of developing contains solvent A and solvent B, which are organic solvents, and solvent C, which is an organic solvent and is less likely to dissolve the resist film than the solvent A and the solvent B. The boiling point of the solvent A is higher than that of the solvent C, and the boiling point of the solvent C is higher than that of the solvent B.

Description

Manufacturing method and developer of a transfer mask

The present invention relates to a method for manufacturing a transfer mask and a developer, and more particularly, to a method for manufacturing a transfer mask and a developer applied when forming a resist pattern from a resist film formed with a chemically amplified and negative resist liquid.

Generally, in the manufacturing process of a semiconductor device etc., formation of a fine pattern is performed using the photolithography method. In the micro-pattern transfer process at the time of implementing this photolithography method, the mask for transfer is used. This transfer mask is generally manufactured by forming a desired fine pattern (concave-convex pattern) on the light-shielding film of the mask blank as an intermediate body. Then, in order to form a desired fine pattern on the light-shielding film, a resist film is formed so as to cover the light-shielding film. In order to produce a transfer mask from a mask blank, first, the resist film is exposed to light corresponding to a predetermined shape, and then developed to form a resist pattern having irregularities from the resist film. Then, using the resist pattern as a mask, etching is performed on the light-shielding film to form a desired fine pattern on the light-shielding film.

A resist liquid is used when forming a resist film on the surface of a mask blank. Various types of the resist liquid exist. For example, there exists a positive resist liquid in which an exposed part becomes soluble, and conversely, a negative resist liquid in which the exposed part hardens|cures and becomes insoluble.

When a positive resist solution is used, the exposed portion becomes a light transmitting portion in the transfer mask. At present, a movement to enlarge the light-transmitting portion is actively carried out. However, if the light-transmitting portion is to be enlarged, of course, the exposure portion must be enlarged. Assuming that exposure is performed by drawing like electron beam drawing, a very large amount of time is required to complete the exposure.

On the other hand, when a negative resist solution is used, the portion not exposed to light becomes the light transmitting portion in the transfer mask. Therefore, in order to enlarge the light-transmitting part, what is necessary is just to make the exposure part small. That is, if exposure is performed by drawing like electron beam drawing, the time required to complete the exposure becomes very small. In this regard, in recent years, the frequency of using a negative resist solution in manufacturing processes, such as a transfer mask, is increasing.

However, points to be taken into consideration when developing a resist film using a negative resist solution are suggested by Patent Documents 1 and 2.

That is, if the affinity between the developer and the resist film used in development for the resist film is high, the convex portions (exposed portions) in the resist pattern will swell by the developer, no matter how hardened and insoluble by exposure. there is a risk of doing When the resist pattern swells, for example, when drying, the pattern shrinks unevenly, dents or protrusions are formed in the convex portions, and the line width uniformity in a plan view is remarkably reduced. As a result, when a conductive portion having a shape corresponding to a resist pattern is formed in the future in a transfer mask or the like, adjacent conductive portions spaced apart from each other are formed adjacent to each other more than imagined, resulting in a short circuit. There is also a risk of performance degradation.

In addition, the so-called undercut phenomenon in which the root of the convex portion in the resist pattern (the portion in contact with the underlying light-shielding film) dissolves more than expected and becomes depressed due to the affinity of the developer and the resist film. There is also a risk that the pattern may collapse.

In order to eliminate the above concerns, in Patent Documents 1 and 2, as a developer, a good solvent with a low boiling point (a solvent with high affinity with the resist film) and a poor solvent with a high boiling point ( A mixture of a solvent having low affinity with the resist film) is used. By doing in this way, first, since the ratio of the good solvent in a developing solution decreases, a resist pattern becomes comparatively difficult to swell, and the dent which is the root of a resist pattern is also suppressed.

Japanese Patent Laid-Open No. 2011-65105 Japanese Patent Laid-Open No. 2013-7785

As a result of the present inventor examining the technique described in said patent document 1 and 2, the following subject newly became clear.

The problem is, as shown in Fig. 3(b) (corresponding to the comparative example of the present specification, which will be described later), for example, distortion (“bending” or “bending” or “ It is said that there is a possibility that there is a risk of burrowing.

The big problems of swelling of a resist pattern and collapsing of a pattern are surely solved by said patent document 1 and 2. On the other hand, while the performance of the semiconductor device etc. manufactured using the transfer mask is improving day by day, the performance requested|required is also increasing day by day. In such a situation, the above distortion can also affect LER (Line Edge Roughness), which is one index for evaluating the shape of the resist pattern, and furthermore, it has an effect on maximizing performance in semiconductor devices. There is a risk of giving

SUMMARY OF THE INVENTION It is an object of the present invention to provide a technique for reducing swelling of a resist pattern, collapsing of a pattern, and distortion of a resist pattern, and forming a resist pattern having a linear pattern edge.

MEANS TO SOLVE THE PROBLEM This inventor added examination about the method of solving said subject. At that time, under the recognition that the techniques described in Patent Documents 1 and 2 described above are effective techniques for suppressing the occurrence of swelling of the resist pattern and collapse of the pattern, the cause of the occurrence of distortion of the resist pattern was studied. As a result, the present inventors obtained the following knowledge.

That is, if it is the technique of patent documents 1 and 2, since the boiling point of a good solvent is comparatively low, in the initial stage of a drying process, a good solvent will volatilize. That is, since the good solvent volatilizes in a state in which all the soluble parts (unexposed parts) of the negative resist film could not be sufficiently dissolved, the inventors guessed that the resist pattern might be jagged when viewed in a plan view.

Further, in the techniques described in Patent Documents 1 and 2, the good solvent first rapidly volatilizes from the convex portions of the resist pattern that have absorbed a certain amount of the good solvent without going to swelling. When the convex portion of the pattern is viewed in a plan view, the inventor of the present invention guessed that a curvature may occur.

Based on said knowledge, this inventor investigated. As a result, in addition to "a good solvent with a low boiling point" and "a poor solvent with a high boiling point", a method of adding "a good solvent with a higher boiling point" as a component of the developer was conceived. In this way, a good solvent is left on the resist pattern until the final stage in the drying step, and the soluble portion of the negative resist film is sufficiently dissolved, and the method of suppressing rapid depression of the resist pattern has been contemplated.

The configuration of the present invention made on the basis of this knowledge is as follows.

<Configuration 1>

The 1st structure of this invention is a manufacturing method of the mask for transcription|transfer.

This manufacturing method comprises the steps of preparing a substrate having a thin film, forming a resist film on the surface of the thin film, exposing the resist film, and developing the resist film after exposure to form a resist pattern. It includes a step of forming a layer, and a step of etching the thin film using the resist pattern as a mask.

In the step of forming the resist pattern, the resist film is a resist film formed with a chemically amplified and negative resist solution.

Further, in the production method of the present invention, the developer used in the developing step is an organic solvent, solvent A and solvent B, and an organic solvent, and solvent C is less difficult to dissolve the resist film than the solvent A and solvent B. is included, the boiling point of the solvent A is higher than the solvent C, and the boiling point of the solvent C is higher than the solvent B.

According to this configuration, the infiltration of the developer solution into the resist pattern is suppressed by including a poor solvent having low affinity for the resist, and problems such as swelling of the resist pattern and collapse accompanying it can be suppressed. Moreover, it also has the effect that a pattern edge can be smoothed in the final stage of drying of a developing solution by adding a little good solvent with a boiling point higher than a poor solvent.

In addition, the "good solvent" as used herein is a solvent capable of dissolving the resist composition before exposure while maintaining a chemically stable state, and the dissolution rate for the resist film is 5 nm/sec or more at 23°C, preferably 10 Nanometer/sec or more, More preferably, it refers to a thing of 12 nm/sec or more. In addition, "poor solvent" refers to a solvent in which the resist composition before exposure cannot be dissolved. For example, when the resist composition solution is diluted 10 times or more with a poor solvent, the dilution solution may become cloudy due to precipitation of the resist composition. refers to the solvent The specific poor solvent has a specific dissolution rate for the resist film of 1 nm/sec or less, preferably 0.5 nm/sec or less, more preferably 0.3 nm/sec or less, and substantially insoluble 0.01 nm/sec. The following are particularly preferred solvents.

<Configuration 2>

In the second configuration of the present invention, in the configuration described in the first, the dissolution rates of the solvent A and the solvent B in the resist film are 10 nm/sec or more at 23° C., and the solvent C of the resist The dissolution rate for the film is characterized in that it is 0.5 nm/sec or less at 23°C.

When the dissolution rates of solvent A and solvent B, which are good solvents, are within the above ranges, the development rate can be maintained even when mixed with solvent C, which is a poor solvent. In addition, when the dissolution rate of the solvent C, which is a poor solvent, is within the above range, the penetration of the solvent C into the exposed portion of the resist film does not substantially occur, so that development such as swelling caused by the developer can be more effectively suppressed.

Further, in the case of a good solvent, the faster the dissolution rate into the resist film is, the better, and in the case of a poor solvent, the slower the dissolution rate in the resist film is. Therefore, the upper limit of the dissolution rate of the good solvent is not particularly limited, and the lower limit of the dissolution rate of the poor solvent is not particularly limited. .

<Configuration 3>

A third configuration of the present invention is the configuration described in the first or second aspect, wherein the solvent B has a higher dissolution rate in the resist film than the solvent A.

Although the solvent A and the solvent B are good solvents, among them, by increasing the dissolution rate of the solvent B in the resist film, it becomes possible to clarify the role division between the solvent A and the solvent B. That is, while solvent B is the main one for dissolving the resist film, it has a low boiling point and is relatively easy to volatilize. On the other hand, solvent A does not easily dissolve the resist film as much as solvent B, but has a high boiling point and is relatively difficult to volatilize, contributing to smoothing of the pattern edge in the drying process after development.

<Configuration 4>

A fourth configuration of the present invention is the configuration according to any one of claims 1 to 3, wherein the volume fraction of the solvent A in the developer is 5% or more and 10% or less.

If the ratio of solvent A contained in the developer is within the above range, smoothing (smoothing) of the pattern edges can be effectively performed without causing swelling of the resist pattern due to the components of the good solvent remaining in the final stage of volatilization of the developer. .

<Configuration 5>

A fifth configuration of the present invention is the configuration according to any one of the first to fourth aspects, wherein the boiling point of the solvent A is 140°C or more and 250°C or less.

The solvent A contributes to the smoothing of the pattern edge in the drying process after image development. When volatilization of the solvent A is too fast, smoothing will become inadequate and distortion will arise, conversely, when it is too late, smoothing will be performed excessively and a pattern edge will become round. However, when the boiling point of the solvent A is in the above range, a pattern having a linear shape and a rectangular cross-sectional shape can be formed by smoothing.

<Configuration 6>

A sixth configuration of the present invention is the configuration according to any one of claims 1 to 5, wherein at least one of the solvent A and the solvent B is the same as at least one of the solvents constituting the resist solution. do.

The solvent constituting the resist liquid can stably maintain the dissolved state of the resist composition without changing the structure of the resist composition, which is a solute of the resist liquid. When such a solvent is contained in the component of the developing solution, when a resist pattern is formed by development using an organic solvent, it is possible to reliably elute the unexposed portion of the resist film. At the same time, since no chemical change occurs in the exposed portion (resist pattern) in the resist film, it is preferable. Further, it is preferable that at least the solvent B is the same as at least one of the solvents constituting the resist solution.

<Configuration 7>

A seventh configuration of the present invention is the configuration according to any one of claims 1 to 6, wherein the volume fraction of the solvent C in the developer is 30% or more.

When the solvent C, which is a poor solvent, is 30% or more, penetration of the developer into the exposed portion of the resist pattern during development is suppressed, so that the swelling of the resist pattern is more effectively suppressed.

<Configuration 8>

An eighth configuration of the present invention is the configuration according to any one of claims 1 to 7, wherein the volume fraction of the solvent C in the developer is 50% or more.

When the solvent C, which is a poor solvent, is 50% or more, penetration of the developer into the exposed portion of the resist pattern during development is more reliably suppressed, so that the swelling of the resist pattern is particularly effectively suppressed.

<Configuration 9>

A ninth configuration of the present invention is the configuration according to any one of claims 1 to 8, wherein in the step of etching the thin film, dry etching using a reactive gas as an etchant is performed, and the reactive gas contains an isotropic etching gas characterized by being

In addition, the "isotropic etching gas" as used herein refers to a gas to which the etching gas acts not only in the thickness direction of the thin film but also on the sidewall of the pattern during formation when etching the thin film to form (patterning) the concave-convex pattern on the thin film. In this case, the etching rate in the thickness direction of the thin film and the etching rate to the sidewall do not need to be equal.

When the etching gas used for patterning the thin film contains isotropic etching gas, the formed thin film pattern tends to have a pattern shape in which the distortion shape of the resist pattern is synergistically reflected. In this invention, since distortion of a resist pattern is suppressed, even if the etching gas used for patterning of a thin film is isotropic, a linear thin film pattern can be formed.

<Configuration 10>

A tenth configuration of the present invention is the configuration described in the ninth aspect, wherein chromium is included in the composition of the surface layer of the thin film, and the reactive gas is a mixed gas containing at least oxygen and chlorine.

Since the layer containing chromium in its composition has etching selectivity with respect to the layer containing silicon in its composition, it is applied to a hard mask or the like of a layer containing silicon in its composition, and thus is easily applied to the surface layer of a thin film. The layer containing chromium in its composition is etched by dry etching with a mixed gas containing chlorine and oxygen, but since the mixed gas containing chlorine and oxygen has isotropy, distortion in the shape of the resist pattern used as the mask is not affected. If it exists, it will form in the shape which raised distortion of a resist pattern in the thin film pattern obtained.

In the structure of the present invention, since distortion of the resist pattern and the like are suppressed, a linear thin film pattern can be formed even when a mixed gas of oxygen and chlorine is used as the etching gas in the thin film of the surface layer containing chromium in the composition.

<Configuration 11>

The eleventh configuration of the present invention is a developing solution used when forming a resist pattern from a resist film formed with a chemically amplified and negative resist solution and performing a developing step.

The developer of the present invention contains solvent A and solvent B, which are organic solvents, and solvent C, which is an organic solvent, which is difficult to dissolve the resist film compared to solvent A and solvent B, and the boiling point of solvent A is higher than that of solvent C. high, and the boiling point of the solvent C is higher than that of the solvent B.

By using this developer, even if a developing process using an organic solvent is employed and a resist pattern is formed using a negative resist, swelling of the resist pattern can be effectively suppressed and a linear pattern edge is obtained. A resist pattern can be formed.

ADVANTAGE OF THE INVENTION According to this invention, the swelling of a resist pattern, pattern collapse, and distortion of a resist pattern can be reduced, and the technique of forming a resist pattern with a linear pattern edge can be provided.

BRIEF DESCRIPTION OF THE DRAWINGS It is a process drawing of the manufacturing method of the mask for transcription|transfer in this embodiment.
Fig. 2 is a graph showing the results when the horizontal axis represents the exposure intensity (DOSE amount) and the vertical axis represents the remaining film ratio in the present Example.
3 is an electron micrograph showing an enlarged state of the resist pattern in Example [FIG. 3 (a)] and Comparative Example [FIG. 3 (b)].

EMBODIMENT OF THE INVENTION Hereinafter, embodiment of this invention is described in detail, referring drawings.

In this embodiment, it demonstrates in the following procedure.

1. Manufacturing method of transfer mask

1-A) Thin film-attached substrate (mask blank) preparation process

1-A-a) Substrate preparation process

1-A-b) thin film formation process

1-B) resist film formation process

1-C) Exposure process

1-D) Development process

1-E) Etching process

1-F) Other

2. Effects according to the embodiment

In addition, you may employ|adopt a well-known structure suitably about the structure without description below.

<1. Manufacturing method of transfer mask 50>

The manufacturing method of the mask 50 for transcription|transfer in this embodiment is demonstrated using FIG. 1 : is a process diagram of the manufacturing method of the mask 50 for transcription|transfer in this embodiment. In addition, in this embodiment, in the board|substrate preparation process with a thin film, although the example which prepares the board|substrate 10 and forms the thin film 11 into a film on the board|substrate 10 is shown, the thin film 11 is formed in advance and A form in which a mask blank 5 is prepared and a resist film is formed thereon is also included in the aspect of the present invention.

1-A) Thin film-attached substrate (mask blank) preparation process

1-A-a) Substrate preparation process

First, the substrate 10 used for the transfer mask 50 is prepared. As the substrate 10 of the transfer mask 50, a glass substrate can be used. In the case of the transmissive mask, the substrate 10 is selected from a glass material having a high transmittance to exposure light when forming a pattern on the wafer. In the case of a reflective mask, the low thermal expansion glass which can minimize the thermal expansion of the board|substrate 10 accompanying the energy of exposure light is selected.

Specifically, in the case of a transmissive mask (eg, binary mask, phase shift mask, and gray tone mask), as the material of the substrate 10, synthetic quartz glass, soda-lime glass, aluminosilicate glass, borosilicate glass, Alkali-free glass etc. are mentioned. As a detailed example, synthetic quartz glass having high transmittance with respect to light having a wavelength of 300 nm or less is applied to the substrate 10 of a transfer mask using an ArF excimer laser having a wavelength of 193 nm or a KrF excimer laser having a wavelength of 254 nm as exposure light. It can be used preferably.

In addition, in the case of an EUV mask which is a reflective mask, the substrate 10 has a range of about 0±1.0×10 ⁻⁷ /° C., more preferably, in order to suppress distortion of the pattern to be transferred due to heat during exposure. A SiO ₂ -TiO ₂ based glass, which is a glass material having a low coefficient of thermal expansion within the range of about 0±0.3×10 ⁻⁷ /°C, may be preferably used.

1-A-b) thin film formation process

Next, as shown in FIG. 1A , a thin film 11 is formed on the main surface of the substrate 10 . The thin film 11 formed under the resist film 12 on the surface of the substrate 10 is a thin film 11 selected according to the purpose of the transfer mask 50 to be manufactured. If enumerated, the following (1) to (5) are mentioned.

(1) Thin film of binary mask

In the case of manufacturing a binary mask blank, a thin film 11 having a light-shielding film is formed on a substrate 10 having light-transmitting properties with respect to light having an exposure wavelength.

The light-shielding film includes a material containing a simple transition metal such as chromium, tantalum, ruthenium, tungsten, titanium, hafnium, molybdenum, nickel, vanadium, zirconium, niobium, palladium and rhodium or a compound thereof. For example, the light-shielding film comprised with chromium and the chromium compound which added 1 or more types of elements selected from elements, such as oxygen, nitrogen, and carbon, to chromium is mentioned. Moreover, the light-shielding film comprised with the tantalum compound which added 1 or more types of elements selected from elements, such as oxygen, nitrogen, and boron, to tantalum, for example is mentioned.

The thin film 11 has a two-layer structure of a light-shielding layer and a surface anti-reflection layer, or a three-layer structure in which a back surface anti-reflection layer is added between the light-shielding layer and the substrate 10 . Moreover, it is good also as a composition gradient film|membrane whose composition in the film thickness direction of a light shielding film differs continuously or stepwise.

Moreover, it is good also as the structure of the thin film 11 which has an etching mask film on a light shielding film. This etching mask film is made of a material containing particularly chromium, which has etching selectivity (having etching resistance) with respect to etching of a light-shielding film containing a transition metal silicide, or a chromium compound obtained by adding elements such as oxygen, nitrogen, and carbon to chromium. It is preferable to configure At this time, by giving the etching mask film an antireflection function, the transfer mask 50 may be produced in a state in which the etching mask film is left on the light shielding film.

(2) Thin films of binary masks with different configurations

Moreover, as another example of the thin film 11 of a binary mask, the structure which has the light shielding film containing the material containing the compound of a transition metal and silicon (transition metal silicide, especially molybdenum silicide is included) is also mentioned.

This light-shielding film contains the material containing the compound of a transition metal and a silicon, The material which has these transition metal and silicon, and oxygen and/or nitrogen as a main component is mentioned. Moreover, the material which has a transition metal and oxygen, nitrogen, and/or boron as main components of a light shielding film is mentioned. As the transition metal, molybdenum, tantalum, tungsten, titanium, hafnium, nickel, vanadium, zirconium, niobium, palladium, ruthenium, rhodium, chromium and the like are applicable.

In particular, when the light-shielding film is formed of a compound of molybdenum silicide, the two-layer structure of the light-shielding layer (MoSi, etc.) and the surface anti-reflection layer (MoSiON, etc.) ) is added and has a three-layer structure.

Moreover, it is good also as a composition gradient film|membrane whose composition in the film thickness direction of a light shielding film differs continuously or stepwise.

(3) Thin film of halftone phase shift mask

In the case of manufacturing a halftone phase shift mask, a compound of a transition metal and silicon (including transition metal silicide, particularly molybdenum silicide) is included on a substrate 10 having light transmittance with respect to the wavelength of exposure light used at the time of transfer. A thin film 11 having a light semitransmissive film containing the material is formed.

The light semitransmissive film included in the thin film 11 transmits light with an intensity that does not substantially contribute to exposure (eg, 1% to 30% with respect to the exposure wavelength), and has a predetermined phase difference (eg, 180 degrees). ) to have Further, the halftone phase shift mask has a light semitransmissive portion patterned with this light semitransmissive film and a light transmitting portion that transmits light having an intensity substantially contributing to exposure in which the light semitransmissive film is not formed. By making the relationship substantially inverted with respect to the phase of the light passing through the light-transmitting section, the light passing near the boundary between the light-semitransmissive section and the light-transmitting section and returning to the opposite region by the diffraction phenomenon cancels each other out, and at the boundary In this case, the light intensity is almost zero and the contrast or resolution of the boundary is improved.

This light-semitransmissive film contains, for example, a material containing a compound of a transition metal and silicon (including a transition metal silicide), and a material containing these transition metals and silicon and oxygen and/or nitrogen as main components. can be heard As the transition metal, molybdenum, tantalum, tungsten, titanium, hafnium, nickel, vanadium, zirconium, niobium, palladium, ruthenium, rhodium, chromium and the like are applicable.

Further, in the case of a type having a light-shielding film on the light-semitransmissive film, since the material of the light-semitransmissive film contains a transition metal and silicon, the light-shielding film material is particularly chromium or , preferably composed of a chromium compound in which elements such as oxygen, nitrogen, and carbon are added to chromium.

(4) Thin film of multi-gradation mask

The thin film 11 of the multi-gradation mask has a laminated structure of one or more semi-transmissive films and a light-shielding film.

About the material of the semitransmissive film, in addition to the elements similar to the light semitransmissive film of the said halftone type phase shift mask blank, the material containing metal singlets, alloys, or these compounds, such as chromium, tantalum, titanium, aluminum, is also contained.

The composition ratio and film thickness of each element are adjusted so as to have a predetermined transmittance with respect to the exposure light. As for the material of the light-shielding film, the above-described light-shielding film of the binary mask blank is applicable, but in a laminated structure with a semi-transmissive film, the composition and film thickness of the light-shielding film material are adjusted so as to achieve a predetermined light-shielding performance (optical density).

(5) Thin film of reflective mask

The thin film 11 of the reflective mask has a structure in which a multilayer reflective film for reflecting exposure light is formed on a substrate 10, and an absorber film for absorbing exposure light is formed on the multilayer reflective film in a patterned shape. The light (EUV light) incident on the reflective mask mounted on the exposure machine (pattern transfer device) is absorbed in the portion with the absorber film, and the light image reflected by the multilayer reflective film in the portion without the absorber film passes through the reflective optical system. It is transferred onto the semiconductor substrate 10 through the

The multilayer reflective film is formed by alternately laminating a high refractive index layer and a low refractive index layer. Examples of the multilayer reflective film include Mo/Si periodic multilayer film, Ru/Si periodic multilayer film, Mo/Be periodic multilayer film, Mo compound/Si compound periodic multilayer film, Si/Nb periodic multilayer film, in which Mo film and Si film are alternately laminated for about 40 cycles; Si/Mo/Ru periodic multilayer film, Si/Mo/Ru/Mo periodic multilayer film, Si/Ru/Mo/Ru periodic multilayer film, and the like. The material can be appropriately selected according to the exposure wavelength.

The absorber film has a function of absorbing, for example, EUV light, which is exposure light, and for example, tantalum (Ta) alone or a material containing Ta as a main component can be preferably used. The crystalline state of such an absorber film preferably has an amorphous or microcrystalline structure from the viewpoint of smoothness and flatness.

1-B) resist film formation process

Next, as shown in FIG. 1B , a resist film 12 is formed on the thin film 11 of the mask blank 5 . The resist film 12 is formed of a chemically amplified and negative resist liquid. As the resist solution, a known resist solution may be used as long as it is a chemically amplified and negative resist solution. Substances constituting the resist film 12 are listed below.

The resist solution in the present embodiment contains at least a base polymer, a photoacid generator, a crosslinking agent that crosslinks the base polymer by the action of an acid, and a solvent.

The base polymer is not particularly limited as long as it has a functional group that can be crosslinked when a crosslinking reaction by a crosslinking agent starts with the generation of an acid. Specific examples thereof include polyhydroxystyrene-based resins, novolak resins, and acrylic resins having a polar group (eg, carboxyl group, alkoxyl group, hydroxyl group, alkoxycarbonyl group, etc.). This embodiment relates to a polyhydroxystyrene-based polymer, and is particularly effective.

The crosslinking agent is a crosslinking agent having a functional group that can be crosslinked with the base polymer, and is composed of a substance that exhibits crosslinking ability by the action of an acid.

A hydroxymethyl group, an alkoxymethyl group, an acyloxymethyl group, or an alkoxymethyl ether group is mentioned as a functional group, The compound or resin which has these 2 or more is mentioned.

The acid generator is not particularly limited as long as it is a known agent, but a compound that generates at least any one of sulfonic acid, bis(alkylsulfonyl)imide, or tris(alkylsulfonyl)methide upon irradiation with actinic light or radiation is desirable.

Although it does not specifically limit as a solvent which can be used when manufacturing a composition, As long as it dissolves each component, For example, alkylene glycol monoalkyl ether carboxylate (propylene glycol monomethyl ether acetate (PGMEA; 1-methyl oxy-2-acetoxypropane), etc.), alkylene glycol monoalkyl ether (propylene glycol monomethyl ether (PGME; 1-methoxy-2-propanol: BP119°C), etc.), alkyl lactate (ethyl lactate, methyl lactate, etc.) ), cyclic lactones (γ-butyrolactone, etc., preferably having 4 to 10 carbon atoms), chain or cyclic ketones (2-heptanone, cyclohexanone, etc., preferably having 4 to 10 carbon atoms), alkylenecarbo nate (ethylene carbonate, propylene carbonate, etc.), alkyl carboxylate (alkyl acetate, such as butyl acetate, is preferable), alkoxy alkyl acetate (ethyl ethoxypropionate), etc. are mentioned. In particular, PGMEA and PGME are preferable.

In addition, other components, such as surfactant, a basic component, a sensitizer, a light absorber, and antioxidant, may be contained in a composition.

In addition, as for the specific formation method of the resist film 12, you may use a well-known method. For example, you may spin-coat a resist liquid with respect to the surface of the mask blank 5, and bake after that.

By the above, the mask blank 1 with a resist used for manufacture of the transfer mask 50 is produced.

1-C) Exposure process

Next, as shown in Fig. 1C, the formed resist film 12 is exposed to a predetermined shape. About the method of specific exposure, you may use a well-known method. For example, you may employ|adopt the exposure method used for each mask mentioned in 1-A-b) thin film formation process.

1-D) Development process

One of the major characteristics of this embodiment is the developing process. By the developing step, as shown in Fig. 1(d), a resist pattern is formed. The specific operation itself of the image development process may use a well-known method. However, the developer used in this step is composed of at least solvent A and solvent B, which are organic solvents, and solvent C, which is an organic solvent, which is difficult to dissolve the resist film 12 compared to solvents A and B. The solvent A has a higher boiling point than the solvent C, and the solvent C has a higher boiling point than the solvent B. Hereinafter, the solvent A and the solvent B are referred to as a "good solvent" and the solvent C is referred to as a "poor solvent".

[Component of Good Solvent A]

As the good solvent A, an ester solvent, a ketone solvent, a glycol ether solvent, an alcohol solvent, or a polar solvent ester solvent of an ether solvent can be used. As for the good solvent A, the thing of a higher boiling point than the boiling point of the poor solvent C should just be used. In addition, when the poor solvent C contains multiple types of solvent, it is made to make the boiling point of the good solvent A higher than the thing with the highest boiling point among multiple types of solvents. A preferred solvent is a solvent in which the difference in boiling points between the poor solvent C and the good solvent A is 2°C or more and less than 20°C, and a particularly preferred solvent is a solvent in which the difference in boiling points between the poor solvent C and the good solvent A is 3°C or more and less than 10°C. is a solvent. If the difference between the boiling points of the poor solvent C and the good solvent A is less than 2°C, the good solvent A will also volatilize immediately after the volatilization of the poor solvent C is completed, so there is a risk that the smoothing of the pattern edge performed by the good solvent A will be insufficient. there is. Moreover, when the boiling point of the good solvent A is 20 degreeC or more higher than the boiling point of the poor solvent C, time will be required for volatilization of the good solvent A, and we are anxious that a drying process will become a long time. Based on the above, it is preferable that the boiling points of the solvent A are 140 degreeC or more and 250 degrees C or less.

(ester solvent)

As an example of the ester solvent, propylene glycol monomethyl ether acetate (PGMEA), amyl acetate, ethyl lactate, ethylene glycol monoethyl ether acetate, propylene glycol monoethyl ether acetate, ethyl methoxypropionate, ethyl 3-ethoxypropionate , ethyl ethoxypropionate, 3-methoxybutyl acetate, methyl acetoacetate, ethyl acetoacetate, butyl lactate, ethylene glycol monobutyl ether acetate, 3-methyl-3-methoxybutyl acetate, diethylene glycol monoethyl ether acetate, and Butyl carbitol acetate is mentioned.

Among them, amyl acetate, propylene glycol monomethyl ether acetate (PGMEA; 1-methoxy-2-acetoxypropane), propylene glycol monoethyl ether acetate, ethyl lactate, ethylene glycol monoethyl ether acetate, and 3-methoxybutyl acetate , diethylene glycol monoethyl ether acetate, butyl lactate, and propylene glycol diacetate are preferable.

(ketone-based, alkyl ketone-based solvents)

Examples of the ketone solvent include acetylacetone, 4-heptanone, cyclohexanone, methylcyclohexanone, 1-octanone, 2-octanone, cycloheptanone, acetonylacetone, 2-nonanone, and acetophenone, isophorone, phenylacetone, ionone, propylene carbonate and methyl amyl ketone. Among these, acetylacetone, 4-heptanone, cyclohexanone, methylcyclohexanone, 1-octanone, 2-octanone, cycloheptanone, acetonylacetone, and 2-nonanone are preferable.

(Glycol ether solvent)

Examples of the glycol ether solvent include propylene glycol propyl ether, ethylene glycol t-butyl ether, 3-methoxybutanol, diethylene glycol dimethyl ether, propylene glycol monobutyl ether, ethylene glycol monobutyl ether, dipropylene glycol dimethyl ether, 3- Methyl-3-methoxybutanol, diethylene glycol ethyl methyl ether, diethylene glycol isopropyl methyl ether, dipropylene glycol monomethyl ether, diethylene glycol diethyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether , Ethylene glycol monohexyl ether, dipropylene glycol propyl ether, diethylene glycol butyl methyl ether, tripropylene glycol dimethyl ether, triethylene glycol dimethyl ether, ethylene glycol 2-ethylhexyl ether, diethylene glycol monobutyl ether, dipropylene glycol Monobutyl ether, tripropylene glycol monomethyl ether, ethylene glycol phenyl ether, and triethylene glycol monomethyl ether are mentioned.

Among these, propylene glycol monoethyl ether, diethylene glycol dimethyl ether, propylene glycol monobutyl ether, 3-methyl-3-methoxybutanol, dipropylene glycol monomethyl ether, and diethylene glycol monomethyl ether are preferable.

(alcoholic solvent)

Examples of the alcohol-based solvent include n-hexyl alcohol, methoxymethyl butanol, n-heptyl alcohol, phenol, 2ethyl-hexanol, 1,2-propylene glycol, n-octyl alcohol, ethylene glycol, 1,3 -Butylene glycol, 1,3-propylene glycol, 1, 4- butylene glycol, n-decanol, diethylene glycol, etc. are mentioned. Among them, n-hexyl alcohol, methoxymethyl butanol, n-heptyl alcohol, 2ethyl-hexanol, 1,2-propylene glycol, n-octyl alcohol and ethylene glycol are preferable.

[Component of Good Solvent B]

As a good solvent, the polar solvent ester solvent of an ester solvent, a ketone solvent, and an ether solvent can be used. As for the good solvent B, the thing of a lower boiling point than the boiling point of the poor solvent C should just be used. In addition, when the poor solvent C contains multiple types of solvent, it is made so that the boiling point of the good solvent B is lower than the thing with the lowest boiling point among multiple types of solvent. A preferable solvent is a solvent having a property that the difference between the boiling points of the poor solvent C and the good solvent B is 50°C or more and 5°C or less, and a particularly preferable solvent is a solvent having a property of 30°C or more and 10°C or less than the boiling point of the poor solvent C. If the difference between the boiling points of the poor solvent C and the good solvent B is less than 5° C., the poor solvent C will also volatilize along with the volatilization of the good solvent B. There is this. Moreover, when the difference of the boiling point of the poor solvent C and the good solvent B becomes 50 degreeC or more, time will be required for volatilization of the poor solvent C, and we are anxious that a drying process will become a long time. Based on the above, the boiling point of the solvent B is preferably 70°C or higher (preferably 80°C or higher) and 170°C or lower.

Moreover, it is preferable that the dissolution rate with respect to the resist film 12 is faster than the good solvent A of good solvent B. Both the good solvent A and the good solvent B are good solvents, but among them, by increasing the dissolution rate of the good solvent B in the resist film, it becomes possible to clarify the role division between the good solvent A and the good solvent B. . That is, while solvent B is the main one for dissolving the resist film, it has a low boiling point and is relatively easy to volatilize. On the other hand, solvent A does not easily dissolve the resist film as much as solvent B, but has a high boiling point and is relatively difficult to volatilize, contributing to smoothing of the pattern edge in the drying process after development.

Moreover, it is good also as the structure of the thin film 11 which has an etching mask film on a light shielding film. This etching mask film is made of a material containing particularly chromium, which has etching selectivity (having etching resistance) with respect to etching of a light-shielding film containing a transition metal silicide, or a chromium compound obtained by adding elements such as oxygen, nitrogen, and carbon to chromium. It is preferable to do At this time, by giving the etching mask film an antireflection function, the transfer mask 50 may be produced in a state in which the etching mask film is left on the light shielding film.

In addition, it is preferable that the solvent B is the same as the solvent constituting the resist solution, or is the same type as at least one solvent out of the plurality in the case of a plurality of solvents constituting the resist solution. "Same type" as used herein refers to using solvent B and a solvent having the same composition as that of the resist film 12 . Since the affinity between the solvent B and the resist film 12 is increased, it is possible to promote dissolution of the resist film 12 after exposure, and thus it is possible to suppress the occurrence of residual dissolution of the resist film 12 .

In addition, this content is the same also about solvent A. That is, at least one of the solvent A and the solvent B is preferably the same as at least one of the solvents constituting the resist solution.

Of course, the high affinity between the solvent B and the resist film 12 leads to swelling of the resist pattern. Therefore, in the present embodiment, the boiling point of the solvent B is set to the lowest among the solvents A to C, and is rapidly removed from the resist pattern in the drying step.

(ester solvent)

As an example of the ester solvent of solvent B, ethyl acetate, propyl formate, isopropyl acetate, isopropyl acetate, n-propyl acetate, butyl formate, isobutyl acetate, butyl acetate, amyl acetate, ethylene glycol monomethyl ether acetate, propylene glycol Monomethyl ether acetate (PGMEA), amyl acetate, ethyl lactate, ethylene glycol monoethyl ether acetate, propylene glycol monoethyl ether acetate, ethyl methoxypropionate, ethyl 3-ethoxypropionate, ethyl ethoxypropionate, 3-acetic acid Methoxybutyl and methyl acetoacetate are mentioned.

Among them, butyl acetate, amyl acetate, propylene glycol monomethyl ether acetate (PGMEA; 1-methoxy-2-acetoxypropane), propylene glycol monoethyl ether acetate, and ethyl ethoxypropionate are preferable. In addition, as shown in Patent Document 2, PEGMEA is known as a raw material for a resist solution.

(ketone-based, alkyl ketone-based solvents)

As an example of the ketone of solvent B, and an alkyl ketone type solvent, For example, methyl ethyl ketone, methyl isobutyl ketone, methyl isobutyl ketone, 3-hexanone, diisobutyl ketone, 2-hexanone, cyclopentanone, acetyl Acetone, methyl amyl ketone, 4-heptanone, and cyclohexanone are mentioned.

Among these, methyl isobutyl ketone, 3-hexanone, diisobutyl ketone, 2-hexanone, cyclopentanone, acetylacetone, methyl amyl ketone, and 4-heptanone are preferable.

(Glycol ether solvent)

Examples of the glycol ether solvent include ethylene glycol dimethyl ether, ethylene glycol dimethyl ether, propylene glycol dimethyl ether, propylene glycol monomethyl ether, ethylene glycol monomethyl ether, propylene glycol monoethyl ether (PGME), ethylene glycol monoethyl. Ether, ethylene glycol isopropyl ether, propylene glycol propyl ether, ethylene glycol t-butyl ether, 3-methoxybutanol, diethylene glycol dimethyl ether, and propylene glycol monobutyl ether are mentioned. Among these, propylene glycol monomethyl ether, ethylene glycol monomethyl ether (PGME), propylene glycol monoethyl ether, and ethylene glycol monoethyl ether are preferable.

(ether solvent)

As an example of the ether type solvent of solvent B, tetrahydropyran and 1, 4- dioxane are mentioned, for example.

(alcoholic solvent)

Examples of the alcoholic solvent of solvent B include isopropyl alcohol, tert-butyl alcohol, cresol, n-propyl alcohol, sec-butyl alcohol, isobutyl alcohol, n-butyl alcohol, and n-hexyl alcohol. there is.

Especially, cresol, n-propyl alcohol, sec-butyl alcohol, and isobutyl alcohol are preferable.

[Component of poor solvent C]

As for the poor solvent C, it is preferable that the nonpolar solvent whose boiling point is 100 degreeC or more and less than 230 degreeC is selected. It is preferable to use aliphatic hydrocarbons and aromatic hydrocarbons having properties in the above boiling point range as non-polar solvents. When it exceeds 230 degreeC, time is required for the drying process after image development. Moreover, by setting it as 100 degreeC or more, excessive evaporation of a developing solution can be suppressed. As for the poor solvent C, 120 degreeC or more and less than 230 degreeC of a boiling point are more preferable, and it is especially preferable that they are 130 degreeC or more and less than 200 degreeC.

Examples of the aliphatic hydrocarbon of the poor solvent C include alkanes, alkenes, allenes and cycloalkanes having 7 to 12 carbon atoms. For example, as examples of alkanes and cycloalkanes, butylcyclohexane, cyclononane, diethylcyclohexane, n-undecane, n-decane, 1-methyl-4-isopropylcyclohexane, methylnonane, tetra and methylcyclohexane, cyclooctane, n-nonane, trimethylheptane, isobutylcyclopentane, trimethylcyclohexane, methyloctane, trimethylhexane, ethylcyclohexane, isopropylcyclopentane, and n-octane. Moreover, 1-nonene, dimethylheptene, octene, dimethylhexene, dimethyloctadiene, methylethylhexadiene, dimethylheptadiene etc. are mentioned as an example of alkenes and allenes.

Among them, cyclodecane, undecane, decane, cyclooctane and nonane are preferable.

As examples of the aromatic hydrocarbon of the poor solvent C, toluene, ethylbenzene, p-xylene, m-xylene, o-xylene, propylbenzene, 1,3,5-trimethylbenzene, 1,2,4-trimethylbenzene, 1, 2,3-trimethylbenzene, diethylbenzene, butylbenzene, triethylbenzene, styrene, etc. are mentioned.

Although it is also possible to use two or more types of poor solvents, in this case, it is necessary that the substance with a higher boiling point than the boiling point of solvent B is not contained and the substance with a higher boiling point than the boiling point of solvent B is contained.

Moreover, there exists a preferable example also about the volume fraction in the developing solution of the good solvents A and B, and the poor solvent C.

It is preferable that the volume fraction of solvent A is 5 % or more and 10 % or less. Since the solvent A has a high boiling point, it has a role of adjusting the shape of the resist pattern until the end of the drying process. When the volume fraction is 5% or more, the effect can be sufficiently exhibited. Moreover, when it is 10 % or less, generation|occurrence|production of the swelling with respect to a resist pattern is fully suppressed.

Moreover, it is preferable that the volume fraction of solvent C is 30 % or more. This is because the occurrence of swelling in the resist pattern is sufficiently suppressed. When the solvent C, which is a poor solvent, is 30% or more, penetration of the developer into the exposed portion of the resist pattern during development is suppressed, so that the swelling of the resist pattern is more effectively suppressed. Moreover, as for the volume fraction of solvent C, it is more preferable that it is 50 % or more. This is because the penetration of the developer into the exposed portion of the resist pattern during development is more reliably suppressed, and the swelling of the resist pattern is particularly effectively suppressed.

1-E) Etching process

It becomes possible to form a resist pattern through the above process. Using the resist pattern, a predetermined pattern is formed on the thin film 11 under the resist pattern. As shown in Fig. 1D, the thin film 11 is etched using the resist film 12 having a predetermined resist pattern formed thereon as a mask. A predetermined transfer pattern is formed on the thin film 11 by etching.

In addition, a well-known method may be used for the method of etching. A preferable example is dry etching using a reactive gas as an etchant in the step of etching the thin film 11 . If the resist pattern of this embodiment is used, even if the reactive gas contains an isotropic etching gas, a transfer pattern with high precision can be formed.

Further, the composition of the surface layer of the thin film 11 is preferably applicable to an etching method in which chromium is contained and the reactive gas is a mixed gas containing at least oxygen and chlorine.

1-F) Other

And as shown in FIG.1(e), the transfer mask 50 in this embodiment is manufactured by removing a resist pattern and performing other processes, such as washing|cleaning, as appropriate. As this method, a well-known thing may be used.

In addition, you may form another film suitably other than said structure. For example, a resist base film may be formed between the thin film 11 and the resist film 12 .

<2. Effects according to the embodiment>

According to this embodiment, the following effects are exhibited.

In addition to "a good solvent with a low boiling point" and "a poor solvent with a high boiling point", "a good solvent with a higher boiling point" is added as a component of the developer so that the good solvent remains on the resist pattern until the final step in the drying process. , while sufficiently dissolving the soluble portion of the negative type resist film 12, it is possible to suppress the rapid depression of the resist pattern. As a result, as shown in Fig. 3(a) (to be described later in the embodiment), it is possible to suppress the occurrence of distortion in the convex portions of the resist pattern, making it possible to form a linear resist pattern in plan view. do. Moreover, at the same time, the occurrence of swelling of the resist pattern and collapse of the pattern can also be suppressed.

As described above, according to the present embodiment, it is possible to provide a technique for forming a resist pattern having a linear pattern edge by reducing swelling of the resist pattern, collapse of the pattern, and distortion of the resist pattern.

<Example>

Next, an Example is shown and this invention is demonstrated concretely. Of course, the present invention is not limited to the following examples.

In addition, in the following examples, while the structure of a developing solution was made into good solvent A and B and poor solvent C, in a comparative example, only good solvent A, good solvent B and poor solvent C, or good solvent A and poor solvent C did with

<First to Seventh Embodiments>

1-A) Thin film-attached substrate (mask blank) preparation process

1-A-a) Substrate preparation process

A translucent substrate 10 (hereinafter also referred to as translucent substrate 10) containing synthetic quartz glass having a main surface dimension of about 152 mm x about 152 mm and a thickness of about 6.25 mm was prepared.

1-A-b) thin film formation process

First, a light-shielding film was formed on the light-transmitting substrate 10 .

A mixed target of molybdenum (Mo) and silicon (Si) (atomic % ratio Mo: Si = 13: 87) is used as a sputtering target on a substrate 10 made of synthetic quartz glass using a single-wafer sputtering device Then, a MoSiN film (lower layer (light-shielding layer)) was formed to a film thickness of 47 nm by reactive sputtering (DC sputtering) in a mixed gas atmosphere of argon and nitrogen.

Then, using a Mo/Si target (atomic % ratio Mo:Si=13:87), in a mixed gas atmosphere of argon and nitrogen, a MoSiN film (upper layer (surface antireflection layer)) is formed to a thickness of 13 nm. , including lamination of the lower layer (film composition ratio Mo: 9.9 atomic %, Si: 66.1 atomic %, N: 24.0 atomic %) and the upper layer (film composition ratio Mo: 7.5 atomic %, Si: 50.5 atomic %, N: 42.0 atomic %) A light-shielding film 2 (total film thickness 60 nm) for an ArF excimer laser (wavelength 193 nm) was formed. In addition, elemental analysis of each layer of the light-shielding film used the Rutherford backscattering analysis method.

Next, an etching mask film was formed on the light-shielding film.

The substrate 10 provided with the light-shielding film was subjected to a heat treatment (annealing treatment) at 450° C. for 30 minutes to reduce the film stress of the light-shielding film.

Then, an etching mask film was formed on the upper surface of the light-shielding film. Specifically, in a single-wafer sputtering apparatus, a CrN film (film composition ratio Cr: 75.3 atomic %, N: 24.7 atomic%) to a film thickness of 5 nm. In addition, by annealing the etching mask film (CrN film) at a lower temperature than the annealing treatment of the light-shielding film, the stress of the etching mask film is reduced as low as possible (preferably, the film stress is substantially zero) without affecting the film stress of the light-shielding film. Adjusted. By the above procedure, the board|substrate 10 for binary masks with the thin film 11 was obtained.

1-B) resist film formation process

On the surface of the thin film 11 on the substrate 10 for a binary mask, a chemically amplified negative resist composition in which the base polymer is a PHS (polyhydroxystyrene)-based polymer (“SLV-12M Negative” manufactured by Fujifilm Electronics Materials Co., Ltd.) type resist") was applied by a spin coating method. Then, the resist film 12 (thickness 100 nm) was formed by heating at 130 degreeC for 600 second.

1-C) Exposure process

Next, a pattern was drawn on the resist film 12 using an electron beam drawing apparatus manufactured by Elionix. Moreover, as a pattern, it exposed so that the width|variety of the convex part (line) of a resist pattern might become 200 nm, and the ratio of a line to a space might become 1:1, for example. It heated at 130 degreeC for 600 second after drawing.

1-D) Development process

Subsequently, in each of Examples 1 to 7, development was performed using an organic solvent. Development was performed by supplying a developing solution to the board|substrate 10 at 5 mL/sec. In Table 1, the components of the developing solution used in each Example, and developing time are shown. In addition, in Example 2, since the unexposed part of the resist film 12 could not all be melt|dissolved in one development, development was performed twice.

Then, drying rotation for 60 second was performed by high-speed rotation, and it was air-dried. In addition, the process after removal of the resist pattern was not performed.

<Comparative Examples 1 to 3>

In the 1st comparative example, the structure of the developing solution was made into good solvent A only. In the 2nd comparative example, the structure of the developing solution was made into only the good solvent B and the poor solvent C. In Comparative Example 3, the configuration of the developer was only the solvent A and the solvent C. Other than that, it carried out similarly to an Example.

<Evaluation>

(contrast evaluation)

For the mask blank 5 on which the resist film 12 of the first to second examples and the first comparative example was formed, the film reduction ratio with respect to the exposure intensity (DOSE amount) was measured. The results are shown in FIG. 2 . Fig. 2 is a graph showing the results when the horizontal axis represents the exposure intensity (DOSE amount) and the vertical axis represents the remaining film ratio in the present Example.

In Examples 1 and 2, the change in the amount of residual film with respect to the amount of DOSE was a curve similar to the tan curve, whereas in Comparative Example 1 in which only PGMEA, a good solvent, was used as the developer, the amount of DOSE was in the range of 15 to 18 µC/cm 2 behavior became irregular. From this point, when all of the developing solutions were good solvents, it turned out that the case where the stability of contrast cannot be acquired.

In addition, in FIG. 2, the behavior of the curve of the 1st comparative example becomes irregular in the range of 15-18 microC/cm<2> of DOSE amount. This inventor has confirmed that there is no measurement error. For example, as a result of electron microscope observation of a sample (DOSE amount of about 16 µC/cm 2 ) having a zero residual film ratio in the curve of Comparative Example 1, the resist pattern was lost. In the first comparative example, the present inventor is earnestly examining the mechanism by which such a phenomenon occurs. In either case, in the first to second embodiments, it was possible to stably form a resist pattern without such a phenomenon occurring.

(Resist residue evaluation)

Regarding the resist-adhered mask blanks 1 after resist development of Examples 1 to 7 and Comparative Examples 1 to 3, the resist residues (resist re-precipitation) after development were evaluated. Evaluation irradiated the halogen lamp from the oblique direction with respect to the mask blank 1 with a resist after development, and visually evaluated the presence or absence of precipitation of a resist residue from the light reflection condition. Specifically, it was set as fail (x) when rough diffuse reflection was confirmed by precipitation of a particulate-form resist residue, and pass (circle) when coarse diffuse reflection was not confirmed.

As a result, in Examples 1 to 3, 5 to 7, and Comparative Examples 1 and 3, diffuse reflection was not observed. In Example 4, it was confirmed that it was slightly opaque in part. In Comparative Example 2, diffuse reflection was confirmed.

Hereinafter, an estimate of the reason will be described.

In the second comparative example, in the drying step after development, in the developer on the mask blank 5 after forming the resist pattern, the good solvent having the ability to dissolve the resist is volatilized. For this reason, as drying progresses, the ratio of the poor solvent increases, and the resist component in the form of fine particles is precipitated in the developer in which the poor solvent is excessive. When the fine particles due to the precipitation of the resist adhere to the surface of the resist pattern or are caught in the space, they remain as resist residues without being discharged to the outside of the substrate. It is considered that the rough-shaped diffuse reflection generated in Comparative Example 2 is due to the resist residue generated in this way.

In the first to third, fifth to seventh implementations, in the drying step after development, the developer on the mask blank 5 after the resist pattern is formed has a good solvent from beginning to end. This is because the good solvent A having a higher boiling point than the poor solvent exists. It is considered that the efficiency of discharging the resist component to the outside of the substrate is maintained by the constant presence of a good solvent for the resist in the developer. In addition, the ratio of the good solvent contained in the developer decreases along with the volatilization of the good solvent B, and even when the resist component is temporarily precipitated, it is re-dissolved again by the good solvent A at the end of drying, and the resist component outside the substrate It is considered that the discharge efficiency of the furnace has been secured.

In addition, in Example 4, since the component of the high boiling point good solvent A was too little, it is thought that the resist component was saturated in the developing solution at the end of drying, and precipitation of a residue arose slightly.

Moreover, in Comparative Example 1, since the developing solution was all comprised with the good solvent, it is thought that precipitation of the resist component did not arise in the drying process. In Comparative Example 3, since the boiling point of the good solvent is higher than the boiling point of the poor solvent, the good solvent was present even at the end of drying, so it is considered that the resist component did not precipitate.

(Resolution evaluation)

For Examples 1 to 7 and Comparative Examples 1 to 3, resolution was evaluated. The resolution investigated the dimensions of the limit for resolving lines and spaces by exposure and development. In addition, there is no significant residue in the original resist dissolving portion, and there is no sticking of the adjacent undissected portion of the resist, and furthermore, there is no curvature or meandering of the pattern greatly deviating from the predetermined drawing pattern portion, and furthermore, there is no electron beam drawing Measure the line width of the undissolved resist portion where the width ratio of the exposed portion (resist undissolved portion) and the non-exposed portion (resist melt portion) that is not drawn with electron beams is a predetermined value, and this line width becomes a limit in practical use set to resolution. In addition, the exposure amount at the time of obtaining the resolution used as the limit in this practical use was set as the required exposure amount. The results are shown in Table 2.

As shown in Table 2, in the first comparative example, which was developed with a developer of a good solvent, pattern collapse was observed when the line width was less than 200 nm. In Comparative Example 3, when the line width was less than 120 nm, the pattern collapsed. This is because, in Comparative Example 3, the volume fraction of the good solvent A in the developer is always 50% or more, and the concentration of the solvent A gradually increases toward the end of drying, and the initial swelling state of the resist pattern is maintained. is thought to have been lowered.

On the other hand, in Examples 1 to 7 and Comparative Examples 2, in which a good solvent and a poor solvent were mixed, it was found that the resolution was excellent. In addition, although the resolution of Example 5 was slightly lower than that of other developing solutions, it is considered that this is due to the small proportion of solvent C.

(Evaluation of line edge roughness)

In order to evaluate the line edge roughness (LER) in the line width 80 nm of Examples 1 - 4, 6, 7, and the 2nd comparative example, the state which expanded the resist pattern was image|photographed with the electron micrograph. . 3 shows the result. In addition, the numerical value of LER was measured using the CD-SEM manufactured by Advanced Test Corporation. In addition, Example 5 evaluated the line edge roughness (LER) in line width 90 nm.

Fig. 3(a) is an SEM image of Example 1, and Fig. 3(b) is an SEM image of Comparative Example 2. In the first embodiment, the edge portion was straight. That is, distortion did not occur when the resist pattern was viewed in a planar view. In addition, the value of LER of the resist pattern was 5.53 nm. Further, the difference between the maximum portion and the minimum portion of the line width of the convex portion of the resist pattern was 7.01 nm. Also in the other examples 2 to 7, the LER value of the resist pattern was less than 6.0 nm. Further, the difference between the maximum portion and the minimum portion of the line width of the convex portions of the resist pattern in Examples 2 to 7 was less than 7.5 nm.

On the other hand, as shown in FIG.3(b), in the 2nd comparative example, the edge part became a gentle broken line. Further, conspicuous concavities were formed in the convex portions of the resist pattern in plan view, such as the portions surrounded by the broken line circles. That is, distortion occurred when the resist pattern was viewed in a planar view. In addition, the value of LER of the resist pattern was 6.32 nm. Further, the difference between the maximum portion and the minimum portion of the line width of the convex portion of the resist pattern was 8.65 nm.

<Production of Warrior Mask>

Using the resist patterns formed in Examples 1 to 3 and Comparative Examples 1 to 2 as a mask, etching is performed on the thin film 11 to form concavo-convex patterns on the thin film 11, and a transfer mask ( 50) was made.

First, using the resist pattern as a mask, dry etching was performed on the etching mask film including the CrN film to form an uneven pattern on the etching mask film. As the dry etching gas, a mixed gas of oxygen and chlorine (O ₂ :Cl ₂ =1:4) was used.

Next, after the remaining resist pattern was removed by an ashing process or the like, the light-shielding film was dry etched by using the uneven pattern formed on the etching mask film as a mask to form a light-shielding film pattern. As the dry etching gas, a mixed gas of SF ₆ and He was used.

Finally, the etching mask film pattern was removed using a mixed gas of oxygen and chlorine (O ₂ :Cl ₂ =1:4).

As described above, the transfer mask 50 was obtained.

<Evaluation of transcription mask>

Next, using the obtained binary type transfer mask 50, a process of exposing and transferring a transfer pattern was performed with respect to the resist film on the semiconductor wafer as the transfer object. The exposure apparatus was performed using the exposure apparatus of the liquid immersion system which uses an ArF excimer laser as a light source.

With respect to the resist film on the semiconductor wafer after exposure, predetermined|prescribed developing process was performed and the resist pattern was formed. Subsequently, a circuit pattern including a line and space (L&S) pattern with a DRAM half pitch (hp) of 40 nm was formed on the semiconductor wafer.

As a result of confirming the circuit pattern on the obtained semiconductor wafer with an electron microscope (TEM), the circuit pattern formed using the transfer mask 50 obtained in the first to third embodiments described above had a DRAM half pitch (hp) of 40 The specification of the line and space pattern of nm was sufficiently satisfied.

On the other hand, in the circuit pattern formed using the transfer mask 50 obtained in Comparative Example 1, many short circuits and disconnections occur in the line and space pattern portion, and the DRAM half pitch (hp) is 40 nm. The specification could not be satisfied.

In addition, although the transfer mask 50 obtained in Comparative Example 2 satisfies the specification of a line-and-space pattern with a DRAM half-pitch (hp) of 40 nm, there are places where the line width is narrow, and the DRAM half-pitch It is thought that it is difficult to cope with the specification of (hp) less than 40 nm.

From the above results, the present Example was able to reduce the swelling of the resist pattern, the collapse of the pattern, and the distortion of the resist pattern, and to form a resist pattern having a linear pattern edge, compared to the comparative example.

In addition, it was found that, in the present Example, a mask for transferring the mask pattern excellent in the pattern shape can be obtained by using the resist pattern excellent in the pattern shape as a mask.

1: Mask blank with resist attached
5: Mask blank
10: substrate
11: thin film
12: resist film
50: warrior mask

Claims (11)

A method for manufacturing a transfer mask, comprising:
A step of preparing a substrate having a thin film;
forming a resist film on the surface of the thin film;
exposing the resist film;
a step of forming a resist pattern by performing a step of developing the resist film after exposure;
etching the thin film using the resist pattern as a mask
is included,
In the process of forming the resist pattern,
The resist film is a resist film formed with a chemically amplified and negative resist solution,
The developing solution used when performing the said developing process contains the solvent A and solvent B which are organic solvents, and the solvent C which is an organic solvent and is difficult to dissolve the said resist film compared with the said solvent A and the said solvent B, The said solvent A The boiling point of the solvent C is higher than that of the solvent C, the boiling point of the solvent C is higher than that of the solvent B, and the volume fraction of the solvent A in the developer is 5% or more and 10% or less. A method for manufacturing a transfer mask, comprising:
A step of preparing a substrate having a thin film;
forming a resist film on the surface of the thin film;
exposing the resist film;
a step of forming a resist pattern by performing a step of developing the resist film after exposure;
etching the thin film using the resist pattern as a mask
is included,
In the process of forming the resist pattern,
The resist film is a resist film formed with a chemically amplified and negative resist solution,
The developing solution used when performing the said developing process contains the solvent A and solvent B which are organic solvents, and the solvent C which is an organic solvent and is difficult to dissolve the said resist film compared with the said solvent A and the said solvent B, The said solvent A The boiling point of the solvent C is higher than that of the solvent C, the boiling point of the solvent C is higher than that of the solvent B, and the volume fraction of the solvent C in the developer is 30% or more. 3. The method of claim 1 or 2,
The dissolution rate of the solvent A and the solvent B in the resist film is 10 nm/sec or more at 23° C.,
The dissolution rate of the solvent C in the resist film is 0.5 nm/sec or less at 23°C. 4. The method according to any one of claims 1 to 3,
The method for manufacturing a transfer mask, wherein the solvent B has a higher dissolution rate in the resist film than the solvent A. 5. The method according to any one of claims 1 to 4,
The boiling point of the solvent A is a method of manufacturing a transfer mask, characterized in that 140 ° C. or more and 250 ° C. or less. 6. The method according to any one of claims 1 to 5,
A method for manufacturing a transfer mask, wherein at least one of the solvent A and the solvent B is the same as at least one of the solvents constituting the resist solution. 7. The method according to any one of claims 1 to 6,
The method for producing a transfer mask, wherein the volume fraction of the solvent C in the developer is 50% or more. 8. The method according to any one of claims 1 to 7,
In the step of etching the thin film, dry etching is performed using a reactive gas as an etchant, and the reactive gas contains an isotropic etching gas. 9. The method of claim 8,
Chromium is included in the composition of the surface layer of the thin film, and the reactive gas is a mixed gas containing at least oxygen and chlorine. A developing solution used when performing a development process accompanying the formation of a resist pattern from a resist film formed with a chemically amplified and negative resist solution, comprising:
The developer contains solvent A and solvent B, which are organic solvents, and solvent C, which is an organic solvent, which is difficult to dissolve the resist film compared to solvent A and solvent B,
The solvent A has a boiling point higher than the solvent C, the solvent C has a higher boiling point than the solvent B, and the volume fraction of the solvent A in the developer is 5% or more and 10% or less. A developing solution used when performing a development process accompanying the formation of a resist pattern from a resist film formed with a chemically amplified and negative resist solution, comprising:
The developer contains solvent A and solvent B, which are organic solvents, and solvent C, which is an organic solvent, which is difficult to dissolve the resist film compared to solvent A and solvent B,
A developer, characterized in that the boiling point of the solvent A is higher than that of the solvent C, the boiling point of the solvent C is higher than that of the solvent B, and the volume fraction of the solvent C in the developer is 30% or more.

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