JP2013021152A - Method for forming resist pattern - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for forming a resist pattern, capable of preventing collapse and slip of a resist pattern after developing and rinsing to eliminate a defect in the pattern.SOLUTION: A method for forming a resist pattern includes the steps of: forming a sensitive resin film as a resist on a material to be etched; selectively irradiating the sensitive resin film with energy by controlling a portion irradiated with the energy; and developing the sensitive resin film selectively irradiated with the energy. The method includes a resist residual film forming method in which a resist residual film remains in a recess between resist protrusions formed by developing.

Description

  The present invention relates to a method for forming a resist pattern in a manufacturing process of a photomask, a nanoimprint mold, and the like.

  In recent years, along with the large integration of semiconductor circuits and downsizing of semiconductor elements, the performance required for lithography technology is increasing, and it is possible to cope with the shortening of the wavelength of the light source and the corresponding in order to realize pattern miniaturization. Development of sensitive resists has been underway.

  By the way, one of the problems that arise when a fine resist pattern, particularly a high aspect ratio resist pattern is formed by the lithography technique, is the collapse or slipping of the resist pattern. The resist pattern collapses or slips when one or both of the adjacent linear resist convex portions are inclined when a large number of linear resist convex portions are arranged and formed in parallel at a predetermined pitch on the substrate. Or a breakage from the base part of the linear resist convex part, or the base part of the linear resist convex part peels off and slides. When such a resist pattern collapses or slips, it directly affects the subsequent microfabrication, and a desired final product cannot be obtained, resulting in a decrease in product yield and a decrease in reliability. End up.

  In order to avoid such a problem, conventionally, a surface treatment layer made of HMDS (Hexamethyldisilazane) is interposed between the resist and the substrate in order to improve the adhesion between the resist and the substrate in the lithography process. Has been used.

  However, due to the recent demand for further miniaturization of the resist pattern, the adhesion between the resist resin and the substrate may not be sufficient even when HMDS is used, which means that the resist pattern collapses or slips after development. For example, when a photomask or nanoimprint mold is manufactured using such a deficient resist pattern after the formation of such a defective resist pattern, a defect occurs in these finely processed products.

  The above-mentioned problems of resist pattern collapse and slipping after development are generally caused by the resist height (aspect ratio), the surface tension of the rinsing liquid in the rinsing process, and the adhesion between the resist and the substrate. JP-A-7-142349 (Patent Document 1) describes an interface between at least one of a developing solution and a rinsing solution for the purpose of preventing a high aspect ratio resist pattern from collapsing in a developing process. A technique for reducing the collapse of the resist pattern by a technique such as reducing the wettability and adhesiveness of the resist pattern surface by mixing an activator or an organic solvent is disclosed. JP-A-10-270306 (Patent Document 2) describes the surface of a semiconductor substrate for the purpose of improving the adhesion between the semiconductor substrate and the resist pattern and obtaining a good resist pattern without film peeling. A technique of a pattern forming method including a step of performing a surface treatment with a surface treatment agent containing a predetermined silane compound instead of conventional HMDS to make the substrate surface hydrophobic is disclosed.

JP-A-7-142349 JP-A-10-270306

  However, according to the proposal disclosed in Japanese Patent Laid-Open No. Hei 7-142349 (Patent Document 1), resist pattern collapse cannot be prevented completely, and dimensional fluctuation due to resist swelling / dissolution occurs to ensure desired accuracy. Problems such as inability to occur may occur. Further, according to the proposal disclosed in Japanese Patent Laid-Open No. 10-270306 (Patent Document 2), the resist pattern collapse cannot be prevented completely, and a compatible silane compound is selected according to the basic skeleton of the resin constituting the resist. Therefore, it can be said that the selection is extremely difficult.

  The present invention was devised on the basis of such a situation, and the purpose thereof is a resist pattern that can suppress the resist pattern from falling and slipping after development and rinsing and can eliminate defects in the resist pattern. It is to provide a forming method.

  In order to solve such problems, the present invention provides a sensitive resin film forming step for forming a sensitive resin film as a resist on a material to be etched, and a portion for irradiating energy to the sensitive resin film. A resist pattern forming method comprising: an exposure step of selectively irradiating with energy by controlling a development step of developing a sensitive resin film selectively irradiated with energy, wherein the resist pattern forming method includes: A resist residual film forming method is provided, in which a resist residual film is present in a concave portion between the resist convex portion and the resist convex portion formed by the step.

  Further, as a preferred embodiment of the resist pattern forming method of the present invention, the resist residual film forming method is arranged such that a compound having a basic functional group is disposed on a material to be etched and a sensitive resin film is positively amplified. The resist residual film is made to exist by deactivating the acid generated on the surface of the material to be etched by irradiating the sensitive resin film with energy.

  As a preferred embodiment of the resist pattern forming method of the present invention, the compound having a basic functional group is configured to be a silane coupling agent.

  As a preferred embodiment of the resist pattern forming method of the present invention, the basic functional group is an amino group and is arranged at the end.

  Further, as a preferred embodiment of the resist pattern forming method of the present invention, the resist residual film forming method includes a sensitive resin film as a negative resist, the exposure step as a first exposure step, and the first exposure step. In addition, the resist residual film is made to exist by performing a second exposure step of irradiating energy to a sensitive resin film at least at a location not irradiated with energy.

  As a preferred embodiment of the resist pattern forming method of the present invention, the irradiation energy used in the second exposure step is configured to be lower than the irradiation energy used in the first exposure step.

  Further, as a preferred aspect of the resist pattern forming method of the present invention, the second exposure step is configured to be performed over the entire region or a necessary portion of the sensitive resin film.

  The resist pattern forming method of the present invention comprises a resist residual film forming method in which a resist residual film is present in a concave portion between a resist convex portion and a resist convex portion formed by development. The resist pattern can be prevented from falling and slipping, and pattern defects can be eliminated.

FIGS. 1A to 1E are schematic cross-sectional views each showing an embodiment of a resist pattern forming method of the present invention over time. 2 (F) to 2 (G) are schematic cross-sectional views showing the time course of one embodiment of the resist pattern forming method of the present invention, which is a process following FIG. 1 (E). FIG. 3 is a cross-sectional view for explaining a modification in the case where the material to be etched is a hard mask layer. 4 (A) to 4 (E) are schematic cross-sectional views each showing another embodiment of the resist pattern forming method of the present invention over time. 5 (F) to 5 (G) are schematic cross-sectional views each showing a process subsequent to FIG. 4 (E) and showing another embodiment of the resist pattern forming method of the present invention over time.

  Hereinafter, embodiments of the resist pattern forming method of the present invention will be described.

  In the present invention, a sensitive resin film forming step for forming a sensitive resin film as a resist on a material to be etched, and a portion that irradiates energy to the sensitive resin film are controlled to selectively irradiate energy. An exposure process, a PEB (Post Exposure Bake) process provided as necessary, a development process for developing a sensitive resin film selectively irradiated with energy, and further stopping the development reaction to form a resist pattern after development. A resist pattern forming method having a rinsing step for removing unnecessary portions, and in particular, the resist pattern forming method of the present invention includes a resist convex portion and a resist convex portion formed by development as essential portions thereof. And a resist residual film forming method for causing a resist residual film to exist in the recesses between the two.

  There are several methods for forming the resist residual film. Hereinafter, embodiments of the resist pattern forming method will be described separately for different resist residual film forming methods.

  In the present specification, the term “exposure (process)” is used as a fixed term in the fine pattern forming process, and this term refers to an electron beam ( The concept of “EB irradiation (process)” replaced with EB) is included. In addition, the “sensitive resin (film)” used in this specification refers to a resin (film) that is sensitive to energy rays such as light and electron beams (EB).

<First Embodiment>
A first embodiment of a resist pattern forming method of the present invention will be described with reference to FIGS. FIGS. 1A to 1E are schematic cross-sectional views showing an embodiment of the resist pattern forming method of the present invention over time, and FIGS. 2F to 2G are respectively FIGS. It is a process following (E), Comprising: It is a schematic sectional drawing which shows one Embodiment of the resist pattern formation method of this invention with time.

(Process for preparing the material to be etched)
As shown in FIG. 1A, a step of preparing a material to be etched 10 to be etched is performed.

The material to be etched 10 may be in the form of a substrate such as a silicon wafer, or a layer to be etched for forming a hard mask formed on the substrate, for example, SiO ₂ , SiN, A laminated film or the like on which Cr, CrN, CrO ₂ or the like is formed may be used, and the material and form of the material to be etched are not particularly limited.

  Here, the material to be etched 10 in the form of a substrate such as a silicon wafer is illustrated so that the drawing can be drawn simply and the understanding of the invention can be made easier.

(Process of disposing a compound having a basic functional group on the material to be etched)
Next, as shown in FIG. 1B, a step of disposing a compound having a basic functional group on the material to be etched 10 is performed. The compound having a basic functional group to be arranged is represented as a film-like material indicated by a thick line formed on the material to be etched 10 in FIG. However, the arrangement form of the compound is not necessarily limited to a film-like material. A compound having a basic functional group may be present on the material to be etched 10 to such an extent that the effects of the present invention can be exhibited. Hereinafter, reference numeral 15 may be referred to as a processing surface.

  As the compound having a basic functional group, a so-called silane coupling agent is preferably used, and in particular, a compound having an amino group as a basic functional group at the terminal is preferable. Such amino groups include those in which hydrogen is substituted with an alkyl group.

  Such silane coupling agents include N-2-aminoethyl-3-aminopropylmethyldimethoxysilane, N-2-aminoethyl-3-aminopropyltrimethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxy. Silane, N-phenyl-3-aminopropyltrimethoxysilane, 3-triethoxysilyl-N-1,3-dimethyl-butylidene-propylamine and the like can be exemplified as preferable examples, but these compounds are not necessarily limited to these compounds. It is not limited.

  In order to arrange such a silane coupling agent on the material to be etched, the silane coupling agent is diluted with a solvent to a concentration of, for example, about 0.01 to 10% by weight, and the diluted solution is used. A liquid film may be formed on the material to be etched by dipping, spin coating, vapor deposition, or the like. Thereafter, by performing baking treatment, chemical bonding by dehydration condensation proceeds to complete the silane coupling treatment. In addition, as said solvent for said dilution, well-known various solvents, such as ethanol, methanol, propylene glycol monomethyl ether acetate, isopropyl alcohol, can be used, for example.

(Sensitive resin film forming process)
Next, as shown in FIG. 1C, a sensitive resin film forming step is performed in which a sensitive resin film 20 as a resist is formed on the surface (treated surface 15) subjected to the silane coupling treatment. In order to form the sensitive resin film 20 as a resist, a spin coating method is usually used, but it is not necessarily limited to this method.

  In the present embodiment, a positive chemically amplified resist (CAR) is used as a sensitive resin for forming a resist.

  As a suitable example, the positive chemically amplified resist includes a mixture of a polymer compound into which a polarity converting group is introduced and a photoacid generator as a main component. For example, an acid-decomposable group may be chemically bonded to a hydroxyl group (OH) at the end of an alkaline water-soluble polymer compound, and an acid generator may be further mixed to form a resist.

  Then, as will be described later, by exposing the sensitive resin film, an acid is generated in the exposed portion, and further, in the PEB (Post Exposure Bake) step described later, the acid diffuses and reacts in the exposed portion. The introduced acid-decomposable group is defused and converted to the original hydroxyl group to make it alkali-soluble. That is, the acid generated in the resist is diffused by PEB and changes many regions to be alkali-soluble. High sensitivity is realized by such a mechanism.

  The positive chemically amplified resist may be appropriately selected from various known materials in consideration of exposure conditions and the like, and is not particularly limited.

(Pre-baking process)
Next, a pre-baking process for solidifying the resist is performed by heating the sensitive resin film 20 as a resist formed on the processing surface 15 on the material to be etched 10 as described above. The heating temperature and heating time in the prebaking process may be appropriately selected in consideration of the physical properties of the resist itself.

(Exposure process)
Next, as shown in FIG. 1D, an exposure process is performed in which the pre-baked sensitive resin film 20 is selectively irradiated with energy by controlling the portion irradiated with energy.

  In order to control a portion to be irradiated with energy, a method of drawing directly on a resist with an electron beam (EB) only at a necessary portion, or an energy source on a mask on which a predetermined light transmissive pattern is formed. A method of irradiating and irradiating energy is used.

As the pattern becomes finer, an energy source with a shorter wavelength is required. For example, a KrF excimer laser, an ArF excimer laser, an F ₂ excimer laser, or the like is preferably used. In addition, X-rays can be used as an energy source, or an EUV light source can be used as an energy source.

  When a positive chemically amplified resist is used as the sensitive resin film 20 as described above, normally, a portion that is not irradiated with energy is not dissolved in the developer, but only a portion that is irradiated with energy is dissolved in the developer. A latent image is formed. Therefore, by the subsequent development processing, resist convex portions are formed only at locations where energy irradiation is not performed, and the resist does not remain at locations where energy irradiation has been performed. However, in this embodiment, since the compound having a basic functional group is disposed on the material to be etched (the treatment surface 15 is formed) as described above, exposure is performed near the surface of the material to be etched. As a result, the acid generated in the resist is neutralized by the base to deactivate the acid. Therefore, as shown in FIG. 1D, the resist in the vicinity of the surface of the material to be etched (near the processing surface 15) cannot be changed to alkali-soluble even after a PEB (Post Exposure Bake) process described later. After the development, an alkali-soluble latent image 20a is formed so that a thin film resist remains near the surface of the material to be etched (near the processing surface 15).

(PEB (Post Exposure Bake) process)
Next, a PEB (Post Exposure Bake) process, which is a heating process before development, is performed after exposure. A heating temperature and a heating time in the PEB process may be appropriately selected in consideration of physical properties of the resist itself.

  The acid generated in the exposed portion of the sensitive resin film by the PEB process further diffuses and reacts in the film, and the introduced acid-decomposable group is defused and converted to the original hydroxyl group, thereby being alkali-soluble. And That is, the acid generated in the resist diffuses by baking, and changes many regions to be alkali-soluble. However, in this embodiment, as described above, the resist in the vicinity of the surface of the material to be etched in which the compound having a basic functional group is disposed cannot be denatured to be alkali-soluble due to acid deactivation. Even after development, a thin film resist (see reference numeral 25 in FIG. 1E) remains in the vicinity of the surface of the material to be etched (near the processing surface 15).

(Development process)
Next, as shown in FIG. 1E, a developing step is performed in which the exposed portion is immersed in a developer to remove the excess portion of the resist. In this step, a convex pattern of resist appears on the material 10 to be etched.

  In the present invention, as described above, a compound having a basic functional group is disposed on the material to be etched, the sensitive resin film is a positive chemically amplified resist, and the sensitive resin film is irradiated by energy irradiation. Since a resist residual film forming method for deactivating the acid generated on the surface of the etching material is provided, as shown in FIG. 1E, between the resist convex portion 21 and the resist convex portion 21 formed by development. The resist residual film 25 can be present in the recesses of the substrate.

  In this manner, a concavo-convex pattern of the resist is formed that includes the resist convex portion 21 and the resist residual film 25 formed in the concave portion between the resist convex portion 21 and the resist convex portion 21.

  The thickness of the resist residual film 25 is about Hr / Hp = 0.02 to 0.1, where Hr is the thickness of the resist residual film 25 and Hp is the thickness of the resist protrusion 21.

  The aspect ratio, which is the ratio between the bottom width W and the height Hp of the resist protrusion, is about 1 to 3.

  Due to the presence of the resist residual film 25, the concavo-convex pattern of the resist has a form in which the bottom thereof is integrally fixed to the substrate with a single film, and the contact area is increased. 21 can be prevented from slipping or falling. The resist residual film 25 can be easily removed in an etching process described later.

(Rinse process)
Next, the supply of the developer is stopped, the development reaction is stopped, and a rinsing process for removing unnecessary portions around the resist pattern is performed. Examples of the unnecessary portion include a resist developer and a residual unnecessary resist after development. As the rinsing liquid, ultrapure water is mainly used, but the rinsing liquid is not necessarily limited thereto, and various cleaning liquids can be used. A solution containing a solvent or a surfactant may be used.

  In the present invention, a resist concavo-convex pattern is formed which includes a resist convex portion 21 and a resist residual film 25 formed in a concave portion between the resist convex portion 21 and the resist convex portion 21 in a concavo-convex shape. Since there is no portion that is in close contact with the substrate in a state where only the convex portion is divided and the contact area is large, the resist pattern composed of the resist convex portion 21 can be prevented from falling, slipping, and the like. Can be eliminated.

  Such an effect can be exhibited not only immediately after the development process but also after a rinsing process (especially a rinsing process using ultrapure water) in which the subsequent resist is particularly likely to fall.

  Through such a rinsing step, a desired cleaned resist uneven pattern is formed. In addition, after the rinsing step, a post-baking step may be provided in order to remove moisture such as a developing solution or a rinsing solution and improve the adhesion of the resist and the etching resistance in the next step, if necessary.

(Residual film removal process)
Next, a residual film removing step is performed in which the resist residual film 25 formed in the concave portion that is a valley between the resist convex portion 21 and the resist convex portion 21 is removed by etching, ashing, or the like. As a result, the resist residual film 25 formed in the concave portion which is a valley is removed, and a part of the material to be etched is exposed. The resist convex portion 21 remains.

(Process of etching material)
Next, as shown in FIG. 2 (F), the exposed portion of the material to be etched is etched to form a desired recess 10a. Such a processing step of the material to be etched can be performed continuously with the above-described residual film removing step.

(Resist removal process)
Next, as shown in FIG. 2G, a resist removing process is performed to remove the resist remaining on the material to be etched by ashing or using a solvent or the like, so that a concavo-convex pattern of the material to be etched 10 is formed.

  In the above description, the material to be etched 10 is, for example, a substrate such as a silicon wafer. However, when the material to be etched 10 is, for example, a laminated film formed on a substrate for forming a hard mask, The state shown in FIG. 2G is replaced with the cross-sectional shape shown in FIG. In FIG. 3, the material to be etched is a hard mask layer 12 provided on a substrate 11, and this hard mask layer 12 is formed using, for example, the resist pattern forming method of the present invention, as shown in FIGS. Etching is performed through the same process as shown in FIG. The concave portion of the hard mask layer 12 that is the material to be etched reaches the surface of the substrate 11 in order to be used as a mask.

<Second Embodiment>
A second embodiment of the resist pattern forming method of the present invention will be described with reference to FIGS. 4 (A) to 4 (E) are schematic cross-sectional views each showing another embodiment of the resist pattern forming method of the present invention over time, and FIGS. 5 (F) to 5 (G) are respectively FIG. 5 is a schematic cross-sectional view subsequent to FIG. 4 (E), showing another embodiment of the resist pattern forming method of the present invention over time.

(Process for preparing the material to be etched)
As shown in FIG. 4A, a step of preparing a material to be etched 10 to be etched is performed. 4A is basically the same drawing as FIG. 1A described above, and the structure of the material to be etched 10 is as described above.

(Sensitive resin film forming process)
Next, as shown in FIG. 4B, a sensitive resin film forming step is performed in which a sensitive resin film 30 as a resist is formed on the material to be etched 10. In order to form the sensitive resin film 30 as a resist, a spin coating method is usually used, but it is not necessarily limited to this method.

  In this embodiment, a negative resist is used as the sensitive resin for forming the resist, and either a non-chemically amplified resist or a chemically amplified resist may be used.

  The negative resist is a type of resist in which the resist resin undergoes a cross-linking reaction and polymerizes when irradiated with energy, and as a result, becomes insoluble in the developer.

  The negative resist may be appropriately selected from various known materials in consideration of exposure conditions and the like, and is not particularly limited.

(Pre-baking process)
Next, a pre-baking step for heating the sensitive resin film 30 as a resist formed on the material to be etched 10 and solidifying the resist is performed. The heating temperature and heating time in the prebaking process may be appropriately selected in consideration of the physical properties of the resist itself.

(Exposure process)
Next, as shown in FIG. 4C, a first exposure step of selectively irradiating the energy by controlling a portion where the pre-baked sensitive resin film 30 is irradiated with energy is performed.

  As described above, in order to control the portion to be irradiated with energy, a method of drawing directly on the resist with an electron beam (EB) only at a necessary portion, or through a mask on which a predetermined light transmissive pattern is formed. A method of irradiating energy by arranging an energy source is used.

As the pattern becomes finer, an energy source with a shorter wavelength is required. For example, a KrF excimer laser, an ArF excimer laser, an F ₂ excimer laser, or the like is preferably used. In addition, X-rays can be used as an energy source, or an EUV light source can be used as an energy source.

When a negative resist is used as the sensitive resin film 30 as described above, the resin is exposed to energy in the first exposure step shown in FIG. Latent image 30a is formed. The portion not irradiated with energy is dissolved in the developer. The energy used in the first exposure step is high energy (K _H ) that can form a sufficient latent image from the surface of the sensitive resin film 30 to the bottom in the film thickness direction.

Next, in the exposure process of the present embodiment, a second exposure process is performed on the sensitive resin film 30 as shown in FIG. The purpose of the second exposure step is to irradiate the portion 39 of the sensitive resin film 30 that has not been irradiated with energy in the first exposure step with low energy (K _L ) energy. The resist in the vicinity of the surface of the material to be etched is polymerized by a crosslinking reaction to form a latent image 30b that is insoluble in the developer.

  Therefore, at least the portion 39 of the sensitive resin film 30 that has not been irradiated with energy in the first exposure step can achieve the object by applying the energy exposure in the second exposure step, but the second exposure. In consideration of the simplicity of the exposure operation of the process, the second exposure process (for the region having the same area or more as the region where the pattern of the sensitive resin film 30 is formed as shown in FIG. It is preferable to perform (overlap exposure). Of course, the second exposure step may be performed so that energy is irradiated only to the portion 39 of the sensitive resin film 30 that has not been irradiated with energy in the first exposure step. Further, the order of the first exposure process (high energy irradiation) and the second exposure process (low energy irradiation) may be switched.

  In particular, in the portion 39 of the sensitive resin film 30 that has not been irradiated with energy in the first exposure process, the resist in the vicinity of the surface of the material to be etched tends to be easily polymerized by low energy energy irradiation in the second exposure process. It is in. This is considered to be caused by a phenomenon caused by electrons entering the sensitive resin film 30 being scattered in the vicinity of the surface of the material to be etched and a part of the electrons being reflected in the sensitive resin film.

  As a result, the thin resist can be left on the portion 39 of the sensitive resin film 30 that was not originally irradiated with energy in the first exposure step, that is, the portion where the surface of the material to be etched should be exposed.

The ratio (K _L ) / (K _H ) of the high energy (K _H ) light energy used in the first exposure process to the low energy (K _L ) light energy used in the second exposure process. )
It is about 0.1 to 0.25.

(PEB (Post Exposure Bake) process)
When a chemically amplified resist is used as the negative resist, a PEB (Post Exposure Bake) process, which is a heating process before development, is performed after exposure. In this case, the heating temperature and heating time in the PEB process may be appropriately selected in consideration of the physical properties of the resist itself.

(Development process)
Next, as shown in FIG. 4E, a developing process is performed in which the exposed portion is immersed in a developing solution to remove excess portions of the resist. In this step, a convex pattern of resist appears on the material 10 to be etched.

  In the present invention, as described above, the sensitive resin film is a negative resist, and in addition to the first exposure step, at least the portion 39 of the sensitive resin film that is not irradiated is irradiated with energy. Since the resist remaining film forming method for performing the overexposure as the exposure step 2 is provided, as shown in FIG. 4E, the concave portion between the resist convex portion 31 and the resist convex portion 31 formed by development is provided. The resist residual film 35 can be present in the substrate.

  The thickness of the resist remaining film 35 is about Hr / Hp = 0.02 to 0.1, where Hr is the thickness of the resist remaining film 35 and Hp is the thickness of the resist protrusion 31.

  The aspect ratio, which is the ratio between the bottom width W and the height Hp of the resist protrusion, is about 1 to 3.

(Rinse process)
Next, a rinsing process is performed to stop the development reaction and remove unnecessary portions around the resist pattern. Examples of the unnecessary portion include a resist developer and a residual unnecessary resist after development. As the rinsing liquid, ultrapure water is mainly used, but the rinsing liquid is not necessarily limited thereto, and various cleaning liquids can be used. A solution containing a solvent may be used.

  In the present invention, a resist concavo-convex pattern is formed which includes a resist convex portion 31 and a resist residual film 35 formed in a concave portion between the resist convex portion 31 and the resist convex portion 31 in a concave and convex shape. Since there is no portion that is in close contact with the substrate in a state where only the convex portion is divided and the contact area is large, the resist pattern composed of the resist convex portion 21 can be prevented from falling, slipping, and the like. Can be eliminated.

  Such an effect can be exhibited not only immediately after the development process but also after a rinsing process (especially a rinsing process using ultrapure water) in which the subsequent resist is particularly likely to fall.

Through such a rinsing step, a desired cleaned resist uneven pattern is formed.
In addition, after the rinsing step, a post-baking step may be provided in order to remove moisture such as a developing solution or a rinsing solution and improve the adhesion of the resist and the etching resistance in the next step, if necessary.

(Residual film removal process)
Next, a residual film removing step is performed in which the resist residual film 35 formed in the concave portion that is a valley between the resist convex portion 31 and the resist convex portion 31 is removed by etching, ashing, or the like. As a result, the resist residual film 35 formed in the concave portion which is a valley is removed, and a part of the material to be etched is exposed. The resist convex portion 31 is in a remaining state.

(Process of etching material)
Next, as shown in FIG. 5F, the exposed portion of the material to be etched is etched to form a desired recess 10a. Such a processing step of the material to be etched can be performed continuously with the above-described residual film removing step.

(Resist removal process)
Next, as shown in FIG. 5G, a resist removing process is performed in which the resist remaining on the material to be etched is removed by ashing, a solvent, or the like, and an unevenness processing pattern of the material to be etched 10 is formed.

Hereinafter, the present invention will be described in more detail with reference to specific experimental examples.
Example 1
A 6-inch silicon wafer substrate was prepared as a material to be etched, and the surface of this substrate was subjected to silane coupling treatment.

  The solution used for the silane coupling treatment was prepared by diluting a silane coupling agent (manufactured by Shin-Etsu Chemical Co., Ltd .: KBM-903 (3-aminopropyltrimethoxysilane)) to 0.05% by weight with an ethanol solvent. After the substrate was immersed in the solution for 30 minutes to form a film, a baking process was performed at 105 ° C. for 30 minutes to complete the silane coupling process.

  On the surface of the silane coupling treatment thus formed, a positive chemically amplified resist sensitive resin solution is spin-coated (rotated) at 3000 rpm for 90 seconds, and then pre-baked at 110 ° C. for 90 seconds. A sensitive resin film having a thickness of 50 nm was formed.

Next, the sensitive resin film thus formed was subjected to selective energy irradiation (line & space = 32 nm & 32 nm) with an electron beam at an exposure amount of 100 μC / cm ² , and then heated at 90 ° C. and 90 ° C. with a hot plate. Second-time PEB (Post Exposure Bake) treatment was performed.

  Next, the resist pattern (line) after development is subjected to paddle development for 60 seconds with a developer solution of tetramethylammonium hydroxide having a concentration of 2.38 wt% on the sensitive resin film subjected to PEB (Post Exposure Bake) treatment. & Space = 32 nm & 32 nm).

  In this embodiment, a compound having a basic functional group is arranged on a silicon wafer as an etching target material, and the sensitive resin film is a positive chemically amplified resist, and the sensitive resin film is applied to the sensitive resin film. Since the resist residual film formation method is used to deactivate the acid generated on the surface of the material to be etched by energy irradiation, the resist convex portion and the resist convex portion formed by development and rinsing as shown in FIG. It was confirmed by observing the cross section of the resist with an SEM image that a residual resist film exists in the recesses between the two. By the way, when applied to the state of FIG. 1E, the thickness of the resist residual film 25 is as follows. When the thickness of the resist residual film 25 is Hr and the thickness of the resist convex portion 21 is Hp, the Hr / Hp ratio is About 0.1. The aspect ratio, which is the ratio between the bottom width W and the height Hp of the resist protrusion, was about 1.56. In addition, the protrusions were not tilted or slipped, and it was confirmed that the resist protrusions vertically formed from the substrate surface formed a sharp line group at a constant pitch.

(Comparative Example 1)
In Example 1 above, the silane coupling treatment on the surface of the silicon wafer substrate was not performed. Instead, the substrate was treated with HMDS (Hexamethyldisilazane), which has been generally performed, and the surface treatment layer was interposed between the resist and the substrate. Other than that, the pattern of the resist convex part was formed in the same manner as in Example 1 above.

  When the state of the pattern of the resist convex portion after rinsing was confirmed by observing the SEM image, it was confirmed that 30% of the line composed of the resist convex portion fell and slipped.

  From the result of the comparison experiment of Example 1 and Comparative Example 1 described above, in Example 1 of the present invention, there was no occurrence of the resist protrusion pattern falling and slipping, and the effect on the pattern falling and slipping was remarkably high. You can see that it has improved.

(Example 2)
A quartz glass substrate was prepared as a material to be etched, and a Cr layer for forming a hard mask was formed on the surface of the substrate by sputtering to a thickness of 20 nm.

  On the Cr layer for hard mask formation formed in this way, a sensitive resin solution of a negative non-chemical amplification resist (Sumitomo Chemical: NEB-22) is spin-coated (rotated) for 90 seconds at 3000 rpm. Thereafter, a sensitive resin film having a film thickness of 300 nm was formed by pre-baking at 90 ° C. for 90 seconds.

Next, the sensitive resin film thus formed was subjected to two-step exposure. That is, selective energy irradiation (line & space = 100 nm & 100 nm) is performed by an electron beam with an exposure amount of 50 μC / cm ² (first exposure step shown in FIG. 4C), and thereafter 10 μC / cm ² . Overexposure with an electron beam was performed on the entire area where the pattern of the sensitive resin film was present at the exposure amount (second exposure step shown in FIG. 4D).

Next, the photosensitive resin film exposed in two steps is subjected to paddle development for 60 seconds with a developing solution of tetramethylammonium hydroxide having a concentration of 2.38% by weight, whereby a resist pattern (line and space after development) is developed. = 100 nm & 100 nm).
In this embodiment, since a sensitive resin film is used as a negative resist and a resist residual film forming method is employed in which the exposure process is a two-step exposure including the overexposure as described above, it is shown in FIG. As described above, a resist residual film exists in the concave portion between the resist convex portion and the resist convex portion formed by performing development and then rinsing processing for 60 seconds using ultrapure water. It was confirmed by observing the cross section of the resist with an SEM image that the resist protrusions perpendicular to the substrate surface formed at a constant pitch and formed a sharp line group. Incidentally, when applied to the state shown in FIG. 4E, the thickness of the resist residual film 35 is Hr when the thickness of the resist residual film 35 is Hr and the thickness of the resist convex portion 31 is Hp. The / Hp ratio was about 0.03. The aspect ratio, which is the ratio between the bottom width W and the height Hp of the resist protrusion, was about 3.0.

(Comparative Example 2)
In Example 2 described above, the overlap exposure (second exposure step shown in FIG. 4D) was not performed. Otherwise, the same pattern of resist protrusions was formed in the same manner as in Example 2.

  When the state of the pattern of the resist convex portion after rinsing was confirmed by observing the SEM image, it was confirmed that the line composed of the resist convex portion was tilted or slipped.

  From the results of the comparison experiment of Example 2 and Comparative Example 2 described above, in Example 2 of the present invention, there was no occurrence of the resist protrusion pattern falling and slipping, and the effect on the pattern falling and slipping was remarkably high. You can see that it has improved.

From the above experimental results, the effect of the present invention is clear. That is, the resist pattern forming method of the present invention is configured to include a resist residual film forming method in which a resist residual film is present in a concave portion between a resist convex portion and a resist convex portion formed by development. The resist pattern can be prevented from falling and slipping after rinsing, and pattern defects can be eliminated.
In particular, in the present invention, after development, the resist is not formed in contact with the material to be etched as a pattern, but is formed as a film on the material to be etched, and the contact area is increased. Can be made slightly smaller, and the fall can be reduced. The residual resist film can be easily removed in the subsequent etching process.

  The present invention relates to a method for forming a resist pattern in a manufacturing process of a photomask, a nanoimprint mold, and the like, and can be used in technical fields that require various fine processing.

DESCRIPTION OF SYMBOLS 10 ... To-be-etched material 10a ... Concave part 15 ... Process surface 20, 30 ... Sensitive resin film 21, 31 ... Resist convex part 25, 35 ... Resist residual film

Claims (7)

A sensitive resin film forming step of forming a sensitive resin film as a resist on the material to be etched; an exposure step of selectively irradiating energy by controlling a portion that irradiates energy to the sensitive resin film; Developing a sensitive resin film selectively irradiated with energy, and a resist pattern forming method comprising:
The resist pattern forming method includes a resist residual film forming method in which a resist residual film is present in a concave portion between a resist convex portion and a resist convex portion formed by development.   In the resist residual film formation method, a compound having a basic functional group is arranged on a material to be etched, the sensitive resin film is a positive chemically amplified resist, and etching is performed by irradiating the sensitive resin film with energy. The resist pattern forming method according to claim 1, wherein the resist remaining film is present by deactivating an acid generated on the surface of the material.   The resist pattern forming method according to claim 2, wherein the compound having a basic functional group is a silane coupling agent.   The resist pattern forming method according to claim 2, wherein the basic functional group is an amino group and is arranged at a terminal.   In the resist residual film forming method, the sensitive resin film is a negative resist, the exposure process is a first exposure process, and in addition to the first exposure process, at least the sensitivity of a portion not irradiated with energy is used. The resist pattern forming method according to claim 1, wherein the resist remaining film is present by performing a second exposure step of irradiating energy to the resin film.   6. The resist pattern forming method according to claim 5, wherein the irradiation energy used in the second exposure step is lower than the irradiation energy used in the first exposure step.   The resist pattern forming method according to claim 6, wherein the second exposure step is performed over the entire area or a necessary portion of the sensitive resin film.

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