JP4871786B2 - Pattern formation method - Google Patents

Description

  The present invention relates to a pattern forming method for forming a pattern by a double patterning method.

A technology (pattern formation technology) that forms a fine pattern on a substrate and processes the lower layer of the pattern by etching using this as a mask has been widely adopted for IC creation in the semiconductor industry and has received great attention. ing.
The fine pattern is usually made of an organic material, and is formed by a technique such as a lithography method or a nanoimprint method. For example, in a lithography method, a resist film made of a resist composition containing a base material component such as a resin is formed on a support such as a substrate, and a mask in which a predetermined pattern is formed on the resist film (mask A process of forming a resist pattern having a predetermined shape on the resist film is performed by performing selective exposure with radiation such as light and electron beam via a pattern and performing development. A resist composition in which the exposed portion changes to a property that dissolves in the developer is referred to as a positive type, and a resist composition that changes to a property in which the exposed portion does not dissolve in the developer is referred to as a negative type.
And a semiconductor element etc. are manufactured through the process of processing a board | substrate by an etching using the said resist pattern as a mask.

In recent years, pattern miniaturization is rapidly progressing due to the advancement of lithography technology. As a technique for miniaturization, the wavelength of an exposure light source is generally shortened. Specifically, conventionally, ultraviolet rays typified by g-line and i-line have been used, but now mass production of semiconductor elements using KrF excimer laser and ArF excimer laser has been started. Lithography using an ArF excimer laser enables pattern formation with a resolution of 45 nm. In addition, in order to further improve the resolution, studies have been made on F ₂ excimer lasers, electron beams, EUV (extreme ultraviolet rays), X-rays, and the like having shorter wavelengths than these excimer lasers.
The resist composition is required to have lithography characteristics such as sensitivity to these exposure light sources and resolution capable of reproducing a pattern with fine dimensions. As a resist composition satisfying such requirements, a chemically amplified resist composition containing a base material component whose solubility in an alkaline developer is changed by the action of an acid and an acid generator that generates an acid upon exposure is used. (See, for example, Patent Document 1). For example, a positive chemically amplified resist usually contains, as a base material component, a resin whose solubility in an alkaline developer is increased by the action of an acid. When it occurs, the exposed part becomes soluble in the alkaline developer.

As one of the methods for further improving the resolution, exposure (immersion exposure) is performed by interposing a liquid (immersion medium) having a higher refractive index than air between the objective lens of the exposure machine and the sample. A so-called immersion lithography (hereinafter referred to as “immersion exposure”) is known (for example, see Non-Patent Document 1).
According to immersion exposure, even when a light source having the same exposure wavelength is used, the same high resolution as when using a light source with a shorter wavelength or using a high NA lens can be achieved, and the depth of focus can be reduced. It is said that there is no decline. In addition, immersion exposure can be performed by applying an existing exposure apparatus. For this reason, immersion exposure is expected to be able to form resist patterns with low cost, high resolution, and excellent depth of focus. In particular, in terms of lithography characteristics such as resolution, the semiconductor industry is attracting a great deal of attention.
Immersion exposure is effective in forming all pattern shapes, and can be combined with super-resolution techniques such as the phase shift method and the modified illumination method that are currently being studied. Currently, as an immersion exposure technique, a technique mainly using an ArF excimer laser as a light source is being actively researched. Currently, water is mainly studied as an immersion medium.

Recently, as a newly proposed lithography technique, there is a double patterning method in which patterning is performed twice or more (see, for example, Non-Patent Documents 2 to 3). According to this double patterning method, a pattern finer than a pattern formed by one patterning can be formed. For example, Non-Patent Document 2 describes a method as shown in FIG.
That is, first, as shown in FIG. 2A, a laminate in which a substrate 101, a lower layer film 102, and a hard mask 103 are laminated is prepared. Next, a resist film is provided on the hard mask 103, and the resist film is selectively exposed through a mask 105 and developed as shown in FIG. A resist pattern 104 having a plurality of trench patterns arranged at a pitch d is formed. Next, after the hard mask 103 is etched using the resist pattern 104 as a mask, the remaining resist pattern 104 is removed. As a result, as shown in FIG. 2C, a hard mask 103 ′ to which the resist pattern is transferred is obtained. Next, as shown in FIG. 2D, the position of the mask 105 is shifted, and a hard mask that fills the voids in the hard mask 103 ′ by applying a resist material onto the hard mask 103 ′. A resist film having a thickness greater than that of 103 ′ is formed. Then, the resist film is selectively exposed through the shifted mask 105 and developed to form a resist pattern 106. Next, after etching the hard mask 103 ′ using the resist pattern 106 as a mask, the remaining resist pattern 106 is removed. As a result, as shown in FIG. 2E, a hard mask 103 ″ to which a pattern in which a plurality of trench patterns with a space width d / 4 are arranged at a pitch d / 2 is transferred is obtained. By etching using “as a mask, the pattern of the hard mask 103” is transferred to the lower layer film 102, and a pattern 102 ′ having a half pitch of the used mask 105 is formed.
As described above, according to the double patterning method, it is possible to form a resist pattern with higher resolution even when using a light source having the same exposure wavelength or using the same resist composition. The double patterning method can be performed using an existing exposure apparatus.
JP 2003-241385 A Proceedings of SPIE, 5754, 119-128 (2005). Proceedings of SPIE, 5256, 985-994 (2003). Proceedings of SPIE, 6153, 615301-1-19 (2006).

However, in the conventional double patterning method, it is usually necessary to provide a lower layer film on the substrate, and in order to form a pattern on the substrate, the resist film is patterned at least twice, and the hard mask in the lower layer is formed. This etching must be performed at least twice.
This invention is made | formed in view of the said situation, Comprising: It aims at providing the novel pattern formation method which can reduce the number of processes in a double patterning method.

In order to achieve the above object, the present invention employs the following configuration.
[1] A pattern forming method for forming a pattern using a chemically amplified resist composition,
A step of applying a first chemically amplified resist composition on a support to form a first resist film, and selectively exposing the first resist film through a first mask pattern. A step of forming a first resist pattern by development, a step of forming a coating film made of a metal oxide film on the surface of the first resist pattern, and a step of forming the coating pattern A step of performing an alkali treatment on the surface of the support, a step of applying a second chemically amplified resist composition on the support on which the coating pattern is formed, and forming a second resist film; the second resist film, the second selectively exposed through a mask pattern and developed to look including a step of forming a pattern, the covering layer, the metal compounds capable of forming a hydroxyl group by hydrolysis ( W) is an organic solvent (S ' The pattern forming method is characterized in that it is formed using a metal oxide film-forming material dissolved in (1) .
[2] The pattern formation according to [1], including a step of baking the coating pattern at a temperature of 200 ° C. or higher after the alkali treatment and before applying the second chemically amplified resist composition. Method.
[3] before Symbol metal compound (W) is a silicon compound having two or more isocyanate groups [1] or [2] The pattern forming method according.

In the present specification and claims, “exposure” is a concept including general irradiation of radiation.
In the present specification, unless otherwise specified, the “alkyl group” includes linear, branched and cyclic monovalent saturated hydrocarbon groups.
The “lower alkyl group” is an alkyl group having 1 to 5 carbon atoms.
“Aliphatic” means that the group or compound does not have aromaticity.
“Aliphatic cyclic group” means a monocyclic or polycyclic group having no aromaticity.

  The present invention can provide a novel pattern forming method capable of reducing the number of steps in the double patterning method.

≪Pattern formation method≫
The pattern forming method of the present invention includes a step of forming a first resist film by applying a first chemically amplified resist composition on a support (hereinafter referred to as a film forming step (1)), and the above. A step of selectively exposing and developing the first resist film through a first mask pattern to form a first resist pattern (hereinafter referred to as a patterning step (1)); A step of forming a coating pattern by forming a coating film made of a metal oxide film on the resist pattern surface (hereinafter referred to as a coating step), and a step of performing an alkali treatment on the support surface on which the coating pattern is formed ( Hereinafter referred to as an alkali treatment step) and a step of forming a second resist film by applying a second chemically amplified resist composition on the support on which the coating pattern is formed (hereinafter referred to as a film forming step). (2) and Cormorant including. A), the second resist film, the second selectively exposed through a mask pattern, forming a developing the pattern (hereinafter, the patterning step (2) is referred to.) And.
In the present invention, it is preferable to include a step of baking the coating pattern at a temperature of 200 ° C. or higher after the alkali treatment and before applying the second chemically amplified resist composition.

Hereinafter, a preferred embodiment of the pattern forming method of the present invention will be described with reference to FIG. The present embodiment is an example in which a positive resist composition is used as the first and second chemically amplified resist compositions.
In the present embodiment, first, as shown in FIG. 1A, a first resist film 2 is formed by applying a first chemically amplified resist composition on a support 1. Next, as shown in FIG. 1B, the first resist film 2 is selectively exposed and developed to form a plurality of resist patterns 3. Next, as shown in FIG. 1C, a plurality of coating patterns 5 are formed by forming coating films 4 made of metal oxide films on the surfaces of the plurality of resist patterns 3, respectively. Next, the support surface on which the coating pattern 5 is formed is subjected to alkali treatment. Next, the coating pattern 5 is baked at a temperature of 200 ° C. or higher. Next, as shown in FIG. 1 (d), the second chemically amplified resist composition is applied onto the support 1 on which the plurality of coating patterns 5 are formed, and the gaps between the plurality of coating patterns 5 are filled. A second resist film 6 is formed. Next, as shown in FIG. 1E, the second resist film 6 is selectively exposed and developed at a position different from the position where the plurality of coating patterns 5 are formed. The exposed portion of the second resist film 6 is removed by development, and as a result, a pattern (hereinafter referred to as this pattern) composed of a plurality of resist patterns 7 (unexposed portions of the second resist film 6) and a plurality of coating patterns 5 is obtained. Thus, a pattern composed of a resist pattern not covered with a coating film and a coating pattern may be referred to as a composite pattern).
In this way, a composite pattern having a narrower pitch than the resist pattern 3 formed in the patterning step (1) is formed on the support 1.
Hereinafter, each process will be described in more detail.

[Film Formation Step (1)]
The support 1 is not particularly limited, and a conventionally known one can be used. For example, a substrate for an electronic component or a substrate on which a predetermined wiring pattern is formed can be exemplified. More specifically, a silicon substrate, a metal substrate such as copper, chromium, iron, and aluminum, a glass substrate, and the like can be given. As a material for the wiring pattern, for example, copper, aluminum, nickel, gold or the like can be used.
Further, the support 1 may be a substrate in which an inorganic and / or organic film is provided on the substrate as described above. An inorganic antireflection film (inorganic BARC) is an example of the inorganic film. Examples of the organic film include an organic antireflection film (organic BARC) and an organic film such as a lower layer film in a multilayer resist method. In particular, it is preferable that a lower layer film is provided because a pattern with a high aspect ratio can be formed on the substrate, which is useful in manufacturing semiconductors.

  Here, the multilayer resist method is a method in which at least one organic film (lower film) and at least one resist film are provided on a substrate, and the lower layer is patterned using the resist pattern formed on the upper resist film as a mask. It is said that a high aspect ratio pattern can be formed. The multilayer resist method basically includes a method of forming a two-layer structure of an upper resist film and a lower film, and one or more intermediate layers (hard films such as metal thin films) between the resist film and the lower film. And a method of forming a multilayer structure of three or more layers provided with a mask layer. According to the multilayer resist method, by securing a required thickness with the lower layer film, the resist film can be thinned and a fine pattern with a high aspect ratio can be formed.

When the organic film is provided, the organic film is formed by, for example, applying a material for forming an organic film in which a resin component or the like constituting the organic film is dissolved in an organic solvent to the substrate with a spinner or the like, preferably 200 to 300 ° C., preferably 30 It can be formed by baking treatment under heating conditions of ˜300 seconds, more preferably 60 to 180 seconds.
The organic film forming material will be described later in detail.
The thickness of the organic film is preferably 10 to 500 nm, more preferably 50 to 450 nm. By setting it within this range, there are effects that a pattern with a high aspect ratio can be formed and sufficient etching resistance can be ensured during substrate etching.

  A hard mask layer made of a silicon-based material may be further provided between the resist film and the organic film. The hard mask layer can be formed by a conventionally known method using a conventionally known silicon-based material.

There is no restriction | limiting in particular as a 1st chemically amplified resist composition, It can select suitably from many chemical amplified resist compositions proposed as a chemically amplified resist composition, and can use it. Details of the chemically amplified resist composition will be described later.
The first chemically amplified resist composition may be a positive resist composition or a negative resist composition. In the present invention, it is preferable to use a positive resist composition.

The first resist film 2 can be formed by applying the first chemically amplified resist composition onto the support 1. The first chemically amplified resist composition can be applied by a conventionally known method using a spinner or the like.
Specifically, for example, the first chemically amplified resist composition is applied onto the support 1 with a spinner or the like, and baked (pre-baked) at a temperature of 80 to 150 ° C. for 40 to 120 seconds, preferably 60. The first resist film 2 can be formed by applying for 90 seconds and volatilizing the organic solvent.
The thickness of the first resist film 2 is preferably 50 to 500 nm, more preferably 50 to 450 nm. By setting it within this range, there are effects such that the resist pattern 3 can be formed with high resolution and sufficient resistance to etching can be obtained.

[Patterning process (1)]
The patterning step (1) can be performed using a conventionally known method. For example, the first resist film 2 is selectively exposed through a mask (mask pattern) on which a predetermined pattern is formed, and a baking process (PEB (post-exposure heating)) is performed at a temperature of 80 to 150 ° C. It is applied for 40 to 120 seconds, preferably 60 to 90 seconds, and is alkali-developed with, for example, an aqueous solution of tetramethylammonium hydroxide (TMAH) having a concentration of 0.1 to 10% by mass.
In the present embodiment, since a positive type resist composition is used as the first chemically amplified resist composition, when alkali development is performed, the exposed portion is removed, while the unexposed portion remains on the support 1 as it is. A positive resist pattern (first resist pattern 3) is formed.
When a negative resist composition is used as the first chemically amplified resist composition, conversely, the unexposed portion is removed, while the exposed portion remains as it is, and a negative resist pattern is formed.
The wavelength used for the exposure is not particularly limited, and includes KrF excimer laser, ArF excimer laser, F ₂ excimer laser, EUV (extreme ultraviolet), VUV (vacuum ultraviolet), EB (electron beam), X-ray, soft X-ray, etc. Can be done using radiation.

At this time, the selective exposure of the first resist film 2 may be normal exposure (dry exposure) performed in an inert gas such as air or nitrogen, or may be performed by immersion exposure.
In immersion exposure, as described above, the portion between the lens, which has been conventionally filled with an inert gas such as air or nitrogen, and the resist film on the wafer is refracted larger than the refractive index of air. Exposure is performed in a state filled with a solvent (immersion medium) having a high rate.
More specifically, the immersion exposure is a solvent (immersion medium) having a refractive index larger than the refractive index of air between the resist film obtained as described above and the lowermost lens of the exposure apparatus. And in that state, it can be carried out by exposing through a desired mask pattern (immersion exposure).
As the immersion medium, a solvent having a refractive index larger than the refractive index of air and smaller than the refractive index of a resist film exposed by immersion exposure is preferable. The refractive index of such a solvent is not particularly limited as long as it is within the above range.
Examples of the solvent having a refractive index larger than the refractive index of air and smaller than the refractive index of the resist film include water, a fluorine-based inert liquid, a silicon-based solvent, and a hydrocarbon-based solvent.
Specific examples of the fluorine-based inert liquid include a fluorine-based compound such as C ₃ HCl ₂ F ₅ , C ₄ F ₉ OCH ₃ , C ₄ F ₉ OC ₂ H ₅ , and C ₅ H ₃ F ₇ as a main component. Liquid etc. are mentioned. The fluorine-based inert liquid preferably has a boiling point of 70 to 180 ° C, more preferably 80 to 160 ° C. It is preferable that the fluorine-based inert liquid has a boiling point in the above range since the medium used for immersion can be removed by a simple method after the exposure is completed.
As the fluorine-based inert liquid, a perfluoroalkyl compound in which all hydrogen atoms of the alkyl group are substituted with fluorine atoms is particularly preferable. Specific examples of the perfluoroalkyl compound include a perfluoroalkyl ether compound and a perfluoroalkylamine compound.
More specifically, examples of the perfluoroalkyl ether compound include perfluoro (2-butyl-tetrahydrofuran) (boiling point: 102 ° C.). Examples of the perfluoroalkylamine compound include perfluorotributylamine ( Boiling point of 174 ° C.).

[Coating process]
Next, a plurality of coating patterns 5 are formed by forming coating films 4 made of metal oxide films on the surfaces of the plurality of first resist patterns 3 formed.
As a method for forming the coating film 4, a method using a metal oxide film forming material in which a metal compound (W) is dissolved in a solvent (S ′) is preferably used. According to this method, the metal oxide film can be formed at a low temperature (for example, room temperature (20 to 25 ° C.)).
The metal oxide film forming material will be described in detail later, but when this metal oxide film forming material is used, the coating film 5 is formed by, for example, applying the metal oxide film forming material to the surface of the pattern. And after forming a coating film, it can form by drying this coating film. At this time, after the coating film is formed and before the drying is completed, the metal compound (W) in the coating film is gradually hydrolyzed by moisture in the air to form a hydroxyl group, and this hydroxyl group undergoes dehydration condensation. As a result, a thin film (coating film) made of a metal oxide is formed on the surface of the resist pattern. Moreover, when the metal oxide film forming material contains an organic substance as will be described later, the formed coating film is a composite thin film of an organic substance and a metal oxide.
At this time, if the resist pattern 3 has a reactive group (preferably a hydroxyl group or a carboxy group) that reacts with the functional group of the metal compound (W) contained in the film forming material, this reactive group and the metal compound (W ) Is reacted or adsorbed, and the bond between the resist pattern 3 and the coating film 4 becomes strong, which is preferable.
The operation for forming the coating film 4 is desirably performed in an inert gas atmosphere from the viewpoint of reactivity control. At this time, in the case where moisture is not contained in the atmosphere, it is necessary to perform a water treatment described later in order to form a film.

As a method for applying the metal oxide film forming material, a known method can be used. For example, a method of immersing the support 1 on which the resist pattern 3 is formed in the metal oxide film forming material (dip coating method). And a method of applying a metal oxide film forming material on the support 1 by a spin coating method. It can also be formed by a method such as an alternating adsorption method.
The temperature (coating temperature) at which the metal oxide film-forming material is applied on the support 1 varies depending on the activity of the metal compound (W) used and cannot be generally limited. What is necessary is just to determine within the range of 100 degreeC.
Further, the time from application of the metal oxide film-forming material on the support 1 to drying (including application and treatment such as washing and adsorption performed as necessary), that is, before hydrolysis. The contact time between the coating film and the pattern, and the temperature between them (contact temperature) vary depending on the activity of the metal compound (W) used, and cannot be generally limited. What is necessary is just to determine within the range similar to application | coating temperature.

  There is no restriction | limiting in particular as a drying method of the said coating film, A well-known method can be used. For example, baking treatment may be performed, a drying gas such as nitrogen gas may be used, and when a metal oxide film forming material is applied using a spinner, the powder is dried as it is. Also good. The upper limit of the baking temperature of the baking treatment is preferably less than 200 ° C, more preferably 190 ° C or less, and further preferably 170 ° C or less. As a minimum of this baking temperature, 100 ° C or more is preferred, 110 ° C or more is more preferred, and 120 ° C or more is still more preferred.

In the coating step, after applying the metal oxide film-forming material, the surface of the support 1 may be washed with an organic solvent (S ″). Thereby, a portion on the support 1 where no resist film exists ( Even if an excess metal compound (W) is adhered to the surface of the non-pattern part, it is washed away by the organic solvent (S ″) or the concentration becomes very thin. On the other hand, the metal compound (W) adhering to the surface of the resist pattern 3 remains as it is because it adheres firmly. As a result, the metal oxide film is sufficiently formed on the surface of the resist pattern 3, but the metal oxide film is not formed or hardly formed on the surface of the non-patterned portion on the support 1, resulting in high coating selectivity. Thus, a metal oxide film (coating film 4) can be formed on the surface of the resist pattern 3.
Further, by performing the cleaning, the coating film 4 becomes thin and uniform. That is, when cleaning is performed, the excess metal compound (W) that is not chemically adsorbed on the resist pattern 3 is removed, while the metal compound (W) that is relatively strongly bonded to the pattern surface by chemical adsorption or the like. ) Remains uniformly on the pattern surface. Therefore, a nanometer level metal oxide thin film is formed with a uniform film thickness, extremely high accuracy, and high reproducibility.

The organic solvent (S ″) is not particularly limited as long as it does not have a functional group that reacts with the metal compound (W), and can be selected from conventionally known organic solvents.
In particular, since the organic solvent (S ″) is applied on the resist pattern 3, it is preferable to select and use an organic solvent (S ″) that does not dissolve the resist pattern 3. When S ″) is applied, the shape of the resist pattern 3 is hardly damaged.
As the organic solvent (S ″), it is particularly preferable to use the same organic solvent (S ′) as that described as the solvent (S ′) in the metal oxide film forming material described later. This further improves the above effect.

The cleaning can be performed using a known method. For example, after supplying an organic solvent (S ″) to the surface of the coating film made of the metal oxide film forming material by a spray method or the like, an excess organic solvent ( S ″) by suction under reduced pressure, immersion cleaning method in organic solvent (S ″), spray cleaning method, steam cleaning method, organic solvent (S ″) on the support by spin coating method The method of apply | coating is mentioned, The spin coat method is especially preferable.
The cleaning conditions (cleaning time, amount of organic solvent (S ″) used, etc.) may be appropriately set in consideration of the cleaning method, the type of organic solvent (S ″), and the like.
For example, when cleaning by a spin coating method, it may be adjusted as appropriate within a range of, for example, about 100 to 5000 rpm and about 1 to 100 seconds.
The cleaning is preferably performed before the solvent (S ′) in the coating film made of the metal oxide film forming material is completely volatilized. Whether the solvent (S ′) is not completely volatilized can be confirmed visually.

In this step, the resist pattern 3 and the metal compound (W) in the coating film are further applied as necessary after the metal oxide film-forming material is applied to form a coating film and then dried. In order to advance the chemical adsorption and / or physical adsorption with the above), a treatment such as leaving may be performed.
In this step, after the coating film is formed and before it is dried, the coating film and water are brought into contact with each other to hydrolyze the metal compound (W) on the film surface, thereby generating a hydroxyl group on the film surface. A hydration treatment may be performed. Thereby, as described later, it becomes easy to form a coating film in which a plurality of coating films are laminated, and thereby the thickness of the coating film can be easily adjusted. That is, the hydroxyl group formed on the surface of the coating film reacts with the metal compound (W) in the coating film formed by applying the metal oxide film-forming material on the surface to be in close contact with each other. A coating film in which the films are laminated is obtained.
As a means for the hydration treatment, a known method can be used without any particular limitation. For example, the sol-gel method in which the coating film is brought into contact with water is the most common. More specifically, there are a method of applying water to the surface of the coating film and a method of immersing the laminate on which the coating film is formed in an organic solvent containing a small amount of water. When the metal compound (W) includes a compound having high reactivity with water, it is left to stand in the atmosphere, and then reacts with water vapor in the atmosphere to be hydrolyzed. Hydrolysis proceeds naturally.
As water, it is preferable to use deionized water in order to prevent impurities and the like from being produced and to produce a high-purity metal oxide.
In addition, by using a catalyst such as an acid or a base in the hydrolysis treatment, the time required for these steps can be significantly shortened.

The thickness of the coating film 4 is preferably 0.1 nm or more, more preferably 0.5 to 50 nm, and further preferably 1 to 30 nm. By setting the thickness to 0.1 nm or more, there is an effect that sufficient resistance to etching, for example, dry etching such as oxygen plasma etching can be obtained.
The thickness of the coating film 4 can be adjusted, for example, by repeatedly performing a series of operations of application, cleaning, and hydration of the metal oxide film forming material. That is, a metal oxide film-forming material is applied to form a coating film, washed, allowed to stand as necessary, and repeatedly subjected to a hydrolysis treatment to obtain a desired thickness. A uniform thin film can be formed.
By such an operation, a coating film having a thickness of several nanometers to several tens of nanometers and, depending on conditions, several hundred nanometers can be formed with high accuracy.
For example, when a film forming material containing a metal alkoxide containing one kind of metal atom, such as silicon tetraisocyanate or titanium butoxide, is used as the metal compound (W), a thin film having a thickness of several angstroms is sequentially laminated depending on the contact conditions. Can be In this case, the increase in the film thickness per cycle corresponds to the number of laminations of the metal oxide film forming material. On the other hand, when fine particles of alkoxide gel are used as the metal compound (W), a thin film having a thickness of about 60 nm can be laminated per cycle. In addition, when forming a coating film using a metal oxide film forming material by a spin coating method, the film thickness can be changed from several nm to about 200 nm by changing the concentration of the solvent used, the metal compound (W), the spin speed, and the like. It can be controlled arbitrarily.
At that time, the coating film 4 in which different types of metal oxide films are laminated can be formed by changing the type of the metal compound (W) used for each cycle.

[Alkali treatment process]
Next, the support surface on which the coating pattern 5 is formed is subjected to alkali treatment.
By the alkali treatment, the solvent resistance, exposure / development resistance and the like of the coating pattern 5 are improved. Therefore, when the second chemically amplified resist composition is applied in the subsequent film formation step (2), or when the second resist film 6 is exposed and developed in the patterning step (2). The covering pattern 5 is maintained on the support without impairing the shape, and as a result, a composite pattern having a good shape is formed on the support 1.
The reason why such an effect is obtained is not clear, but the following can be considered. That is, for example, when a coating film is formed using a silicon compound having two or more isocyanate groups as the metal compound (W), Fourier transform is performed on the coating film with and without alkali treatment. When observed by conversion infrared spectroscopy (FT-IR), the -Si-OH peak decreased and the -Si-O-Si- peak increased when the alkali treatment was performed. From this, cross-linking between a plurality of hydroxyl groups generated by hydrolysis of the metal compound (W) or between the hydroxyl groups and the resist pattern 3 is promoted by the alkali treatment, and the resist pattern surface has good adhesion. It is considered that a dense film is formed. Moreover, it is considered that the penetration of the solvent of the chemically amplified resist composition and the developer is suppressed by forming a dense film.

The alkali treatment can be carried out, for example, by bringing the surface of the support 1 on which the coating pattern 5 is formed into contact with an aqueous alkali solution.
The alkaline aqueous solution is not particularly limited, and for example, those generally used as an alkaline developer, inorganic alkaline aqueous solutions, and the like can be used. As what is generally used as an alkali developing solution, specifically, the above-mentioned 0.1 to 10% by mass of TMAH aqueous solution can be mentioned. Specific examples of the inorganic alkaline aqueous solution include a sodium hydroxide aqueous solution, a potassium hydroxide aqueous solution, and a sodium hydrogen carbonate aqueous solution.
The contact method between the surface of the support 1 and the aqueous alkaline solution is not particularly limited. For example, the method of immersing the support 1 in the aqueous alkaline solution, or the method of applying the aqueous alkaline solution onto the support 1 by spin coating or the like. Etc.
The alkali treatment time varies depending on the type of alkaline aqueous solution used, the type of resist, and the like, but is usually preferably in the range of 5 to 180 seconds, more preferably 10 to 120 seconds, and particularly preferably 15 to 90 seconds.
The alkali treatment temperature is not particularly limited. Usually, the inside of the range of 10-30 degreeC is preferable.

In the alkali treatment step, it is preferable to wash the surface of the support 1 with pure water in order to remove the alkali from the surface of the support 1 after the surface of the support 1 is subjected to alkali treatment.
The washing can be performed using a known method as described above.

[High temperature baking process]
Next, the coating pattern 5 is baked (high temperature baking) at a temperature of 200 ° C. or higher.
By applying high temperature baking, the effect obtained by the alkali treatment is further improved. The reason why such an effect is obtained is that, for example, when a coating film is formed using a silicon compound having two or more isocyanate groups as the metal compound (W), the Fourier transform is performed by changing the baking temperature for the coating film. As observed by infrared spectroscopic analysis (FT-IR), the peak of -Si-OH tends to decrease and the peak of -Si-O-Si- increases as the baking temperature in high-temperature baking is increased. It is conceivable that the crosslinking reaction during the alkali treatment described above is further promoted.
The baking temperature of the high temperature baking is preferably 200 to 250 ° C., more preferably 200 to 230 ° C., considering the heat resistance of the resist pattern 3 and the like.
The baking time is not particularly limited, but usually 10 to 180 seconds is preferable and 20 to 120 seconds is more preferable in consideration of the effect of high-temperature baking, the stability of the resist pattern shape, and the like.
As a baking method, a conventionally known method can be used, and examples thereof include a method using a baking furnace.

[Film Formation Step (2)]
Next, the second chemically amplified resist composition is applied on the support 1 on which the plurality of coating patterns 5 are formed, and the second resist film 6 that fills the gaps between the plurality of coating patterns 5 is formed. .
In the present embodiment, a positive resist composition is used as the second chemically amplified resist composition. As the first chemically amplified resist composition and the second chemically amplified resist composition, the same positive resist composition may be used, or different positive resist compositions may be used.
Similar to the first resist film 2, the second resist film 6 can be formed by a conventionally known method.
The film thickness of the second resist film 6 is preferably at least the same as or higher than the height of the coating pattern 5. That is, when the support 1 is viewed from the second resist film 6 side, the surface is preferably flat.

[Patterning process (2)]
Next, the second resist film 6 is selectively exposed and developed at a position different from the position where the plurality of coating patterns 5 are formed. As a result, a composite pattern comprising a plurality of coating patterns 5 and a plurality of resist patterns 7 newly formed on the second resist film 6 is formed on the support 1.
Here, in the present invention, all are “positions different from the position where the covering pattern is formed” except when they completely coincide with the covering pattern formed in the covering step. Including cases where
In the present invention, it is preferable that the position where the covering pattern 5 is formed and the position where the patterning step (2) is selectively exposed do not overlap at all. Thereby, a narrow pitch pattern in which the interval (pitch) between patterns is narrower than the resist pattern formed in the patterning step (1) can be formed.

The selective exposure at a position different from the position where the covering pattern 5 is formed can be performed by, for example, moving the mask pattern used in the patterning step (1) in the horizontal direction.
Such movement of the mask pattern can be carried out by adjusting the program of the exposure apparatus to be used.
The mask pattern may be translated in one direction or rotated. For example, in the patterning step (1), a line and space resist pattern is formed using a line and space mask pattern in which a plurality of lines are arranged at a constant pitch. In the patterning step (2), the mask pattern is From the line-and-space pitch formed first, the line pattern is formed in the middle position between the line pattern formed in the patterning step (1) by parallel translation in the direction perpendicular to the line direction. Also, a line-and-space composite pattern is formed with a narrow pitch.
More specifically, for example, in the patterning step (1), a line-and-space resist pattern (first resist pattern) having a line width of 100 nm and a line width: space width = 1: 3 is formed, and the patterning step (2) Then, the mask pattern is translated by 200 nm in the direction perpendicular to the line direction to form a line-and-space resist pattern (second resist pattern) having a line width of 100 nm and a line width: space width = 1: 3. Thus, a line-and-space composite pattern having a line width of 100 nm and a line width: space width = 1: 1 can be formed.
In addition, various composite patterns can be formed by rotating and moving the mask pattern used in the patterning step (1) or using a mask pattern different from the mask pattern used in the patterning step (1).
As a method other than the method of moving the mask pattern, a method of moving the stage (the stage on which the substrate is placed) in the exposure machine can also be used.

  In the pattern forming method of this embodiment, after the patterning step (2), a second covering step of forming a coating film made of a metal oxide film on the surface of the formed composite pattern may be performed. . Thereby, the surface of the resist pattern 7 formed on the second resist film 6 in the composite pattern is covered with the coating film made of the metal oxide film, and the etching resistance and the like are improved.

In the pattern forming method of the present embodiment, after the patterning step (2), a series of operations of the covering step, the film forming step (2), and the patterning step (2) may be repeated a plurality of times. .
That is, a coating film made of a metal oxide film is formed on the surface of the formed composite pattern to form a coating pattern, and a chemically amplified resist composition is applied onto the support on which the coating pattern is formed. An operation of forming a resist film, selectively exposing the resist film, and developing to form a composite pattern may be performed a plurality of times. Thereby, a narrower pitch pattern or a complicated pattern can be formed.

In the pattern forming method of the present embodiment, after the patterning step (2), the support 1 may be etched using the formed composite pattern as a mask.
That is, when the support 1 having an organic film provided on the substrate is used, the organic film can be etched. Thereby, a pattern (organic film pattern) faithful to the composite pattern can be formed on the organic film. Furthermore, the substrate can be etched using these patterns (composite pattern and organic film pattern) as a mask.
When a substrate is used as the support 1, that is, when the composite pattern is formed directly on the substrate, the substrate can be etched as it is using the composite pattern as a mask.
Thus, a semiconductor device etc. can be manufactured by etching a board | substrate.
As the etching method, a known method can be used. For example, dry etching is preferable for etching the organic film. In particular, oxygen plasma etching or etching using CF ₄ gas or CHF ₃ gas is preferable from the viewpoint of high resistance of the coating film to etching and production efficiency, and oxygen plasma etching is particularly preferable.
Etching using a halogen gas is preferable for etching the substrate, etching using a fluorocarbon gas is preferable, and etching using CF ₄ gas or CHF ₃ gas is particularly preferable.

  In the pattern forming method of the above embodiment, the high temperature baking process is performed. However, in the present invention, the high temperature baking process is not necessarily performed. After the alkali treatment process, the film forming process (2 ) May be performed.

In the pattern forming method of the above embodiment, a positive resist composition is used as the first and second chemically amplified resist compositions, but the present invention is not limited to this. For example, a positive resist composition may be used as the first chemically amplified resist composition, and a negative resist composition may be used as the second chemically amplified resist composition. A negative resist composition may be used as the product, a positive resist composition may be used as the second chemically amplified resist composition, and a negative resist composition may be used as the first and second chemically amplified resist compositions. You may use thing.
In the present invention, it is preferable that both the first and second chemically amplified resist compositions are positive.

In the pattern formation method of the present invention, a second chemical is formed on the surface of the first resist pattern formed in the patterning step (1) by performing a coating step and an alkali treatment step after the patterning step (1). A coating pattern having excellent resistance to an organic solvent in the amplification resist composition and resistance to exposure and development of the second resist film can be formed. “Tolerance” as used herein means that the coating pattern is applied after the second chemically amplified resist composition is applied (after contact with the organic solvent of the resist composition) or after exposure and development. However, the shape before performing the said process is maintained on a support body, without impairing.
Therefore, even when the second chemically amplified resist composition is applied on the coating pattern and the patterning step (2) is performed, the first chemically amplified resist composition contains the first chemically amplified resist composition. There is no risk that the resist pattern dissolves or that the shape of the coating pattern is damaged by exposure / development.
Therefore, in the conventional double patterning method, as shown in FIG. 2, it is necessary to provide a lower layer film on the substrate, and in order to form a pattern on the substrate, the resist film is patterned at least twice. Although it was necessary to etch the lower hard mask at least twice, in the present invention, it is not always necessary to provide a lower layer film, and it is possible to form a pattern on the substrate without performing etching. is there.
In the present invention, a positive resist composition can be used for both of the two patterning operations. That is, when a second positive resist composition is applied without forming a coating film on a first resist pattern that has been conventionally formed using a positive resist composition, The first resist pattern is dissolved by the organic solvent of the positive resist composition. Therefore, until now, no positive resist composition has been applied on a resist pattern formed using a positive resist composition. However, in the present invention, since the first resist pattern is protected from the organic solvent by forming the coating film, the pattern can be formed by combining the positive resist compositions.
Furthermore, according to the pattern forming method of the present invention, a fine pattern can be formed even by using an existing exposure apparatus or an existing chemical amplification resist composition.

[Metal oxide film forming material]
In the pattern formation method of this invention, in order to form the coating film which consists of a metal oxide film on said 1st resist pattern surface, the metal compound (W) which can produce | generate a hydroxyl group by hydrolysis is an organic solvent ( A metal oxide film forming material dissolved in S ′) (hereinafter sometimes simply referred to as a film forming material) is preferably used.

<Metal compound (W)>
The metal compound (W) is a compound that can generate a hydroxyl group by hydrolysis.
When a film-forming material containing such a metal compound (W) is applied to the resist pattern surface, or when water, preferably deionized water is further applied after application, the metal compound ( W) reacts with moisture in the atmosphere and applied water, and generates hydroxyl groups by hydrolysis. Then, the generated hydroxyl groups are dehydrated and condensed, and a plurality of metal compound (W) molecules are combined to form a dense metal oxide film having a high film density. Such a dense film is excellent in etching resistance because it contains a metal, and since it can be coated at a low temperature, it does not impair the shape of the resist pattern to be coated.
Further, when the resist pattern has a reactive group such as a carboxy group or a hydroxyl group on its surface, the reactive group on the resist pattern surface reacts with a hydroxyl group generated from the metal oxide (W) (dehydration condensation). , Adsorption, etc.) to form a coating film firmly adhered to the resist pattern surface.

As the metal compound (W), for example, a metal compound having a functional group capable of generating a hydroxyl group by hydrolysis can be used.
The functional group is preferably bonded directly to the metal atom.
The number of functional groups is preferably 2 or more per molecule. By having two or more functional groups in one molecule, the hydroxyl groups produced by hydrolysis undergo dehydration condensation, and a plurality of metal compound (W) molecules are continuously bonded to form a strong metal oxide film. It is formed.
In particular, the number of functional groups is preferably 2 or more per metal atom, more preferably 2 to 4, and particularly preferably 4.

Examples of the functional group capable of generating a hydroxyl group by hydrolysis include an alkoxy group, an isocyanate group, and a carbonyl group. Moreover, since a halogen atom also has the same function, a halogen atom is also contained in a functional group in this invention.
Examples of the alkoxy group include linear or branched alkoxy groups having 1 to 5 carbon atoms such as a methoxy group (-O-Me), an ethoxy group (-O-Et), and an n-propoxy group (-O-nPr). , Isopropoxy group (-O-iPr), n-butoxy group (-O-nBu) and the like.
Examples of the halogen atom include a chlorine atom, a fluorine atom, a bromine atom, and an iodine atom, and among them, a chlorine atom is preferable.
Among the above, an alkoxy group and an isocyanate group are carboxy groups on the resist pattern surface, particularly when the film-forming material is applied onto the resist pattern to form a metal oxide film (coating film). The presence of a reactive group such as a hydroxyl group is preferred because it undergoes a condensation reaction with it. As a result, the hydroxyl group formed after hydrolysis and the reactive group on the resist pattern surface undergo a condensation reaction, and the coating film and the resist pattern surface adhere firmly.
Among the above, the carbonyl group and the halogen atom are particularly reactive groups such as a carboxy group and a hydroxyl group on the surface of the resist pattern when the film forming material is applied onto the resist pattern to form a coating film. If present, it adsorbs to this, which is preferable. Thereby, the hydroxyl group formed after hydrolysis and the reactive group on the surface are adsorbed, and the coating film and the resist pattern surface are firmly adhered.
Among these, an isocyanate group and a halogen atom (especially a chlorine atom) are preferable because they have high activity and can easily form a coating film without any heat treatment, and an isocyanate group is particularly preferable.

In the present invention, the metal constituting the metal compound (W) includes boron, silicon, germanium, antimony, selenium, tellurium and the like in addition to a normal metal.
Suitable examples of the metal constituting the metal compound (W) include titanium, zirconium, aluminum, niobium, silicon, boron, lanthanide, yttrium, barium, cobalt, iron, zirconium, tantalum, and the like. Silicon is preferred, and silicon is particularly preferred.
Further, the number of metal atoms in the metal compound (W) may be 1 or 2 or more, preferably 1.

  The metal compound (W) may have an atom or an organic group other than the above-mentioned “functional group capable of generating a hydroxyl group by hydrolysis”. Examples of the atom include a hydrogen atom. Examples of the organic group include an alkyl group (preferably a lower alkyl group having 1 to 5 carbon atoms) and the like, and an ethyl group and a methyl group are preferable.

Examples of the metal compound (W) include the following.
Examples of the metal compound having an alkoxy group (hereinafter sometimes referred to as “metal alkoxides”) include the following.
For example, titanium butoxide (Ti (O-nBu) ₄ ), zirconium propoxide (Zr (O-nPr) ₄ ), aluminum butoxide (Al (O-nBu) ₃ ), niobium butoxide (Nb (O-nBu) ₅ ) Metal alkoxide compounds other than rare earth metals such as silicon tetramethoxide (Si (O-Me) ₄ ) and boron ethoxide (B (O-Et) ₃ );
Metal alkoxide compounds of rare earth metals such as lanthanide isopropoxide (Ln (O-iPr) ₃ ), yttrium isopropoxide (Y (O-iPr) ₃ );
Double alkoxide compounds such as barium titanium alkoxide (BaTi (OR ⁶⁰ ) _x ) (wherein “R ⁶⁰ ” is a lower alkyl group having 1 to 5 carbon atoms, and X is an integer of 2 to 4);
An organic group other than an alkoxy group having two or more alkoxy groups such as methyltrimethoxysilane (MeSi (O-Me) ₃ ) and diethyldiethoxysilane (Et ₂ Si (O-Et) ₂ ) A metal alkoxide compound having:
Examples thereof include metal alkoxide compounds having a ligand such as acetylacetone and having two or more alkoxy groups.

Further, fine particles of alkoxide sol or alkoxide gel obtained by adding a small amount of water to the metal alkoxides and partially hydrolyzing and condensing them can also be used.
Furthermore, a binuclear or cluster type alkoxide compound having a plurality of or plural kinds of metal elements such as titanium butoxide tetramer (C ₄ H ₉ O [Ti (OC ₄ H ₉ ) ₂ O] ₄ C ₄ H ₉ ) In addition, a polymer based on a metal alkoxide compound cross-linked one-dimensionally through an oxygen atom is also included in the metal alkoxides.

As the metal compound having an isocyanate group, a compound having two or more isocyanate groups is preferable, and in particular, the general formula “M (NCO) _X ” (wherein M is a metal atom, and X is 2 to 2). Is an integer of 4.).
Specifically, tetraisocyanate silane (Si (NCO) ₄ ), titanium tetraisocyanate (Ti (NCO) ₄ ), zirconium tetraisocyanate (Zr (NCO) ₄ ), aluminum triisocyanate (Al (NCO) ₃ ), etc. Can be mentioned.

As the metal compound having a halogen atom, a metal halide compound having two or more (preferably 2 to 4) halogen atoms is preferable, and in particular, the general formula "M (X ₁ ) _n1 " 2 or more (preferably 2 to 4) represented by X ₁ is a kind selected from fluorine atom, chlorine atom, bromine atom and iodine atom, and n ₁ is an integer of 2 to 4 And halogenated metal compounds having the following halogen atoms.
The compound having a halogen atom may be a metal complex.
Specific examples include tetrachlorotitanium (TiCl ₄ ), tetrachlorosilane (SiCl ₄ ), and the like. The metal complexes also include cobalt chloride (CoCl ₂₎ or the like.

Examples of the metal compound having a carbonyl group include metal carbonyl compounds such as titanium oxoacetyl acetate (TiO (CH ₃ COCH ₂ COO) ₂ ), pentacarbonyl iron (Fe (CO) ₅ ), and multinuclear clusters thereof.

Among these, a silicon compound having two or more (preferably 2 to 4) isocyanate groups and / or halogen atoms because a metal oxide film having particularly high activity and high etching resistance can be easily formed. In particular, a silicon compound having 2 or more (preferably 2 to 4) isocyanate groups is preferred.
The number of silicon in one molecule of the silicon compound may be 1 or 2 or more, preferably 1. Especially, the compound represented by the following general formula (w-1) is preferable.
SiW _a (w-1)
[Wherein, a represents an integer of 2 to 4, W represents an isocyanate group (NCO group) or a halogen atom, and a plurality of W may be the same or different from each other. ]

In the formula (w-1), a is an integer of 2 to 4, and is preferably 4.
W is an isocyanate group or a halogen atom, and the halogen atom is the same as described above, and is preferably a chlorine atom. Among these, an isocyanate group is preferable.

  A metal compound (W) may be used individually by 1 type, and 2 or more types may be mixed and used for it.

<Solvent (S ')>
Since a solvent (S ') is excellent in the effect of this invention, it is preferable to contain the solvent (S'1) which does not have a functional group which reacts with the said metal compound (W).
The solvent (S′1) is not particularly limited as long as it does not have a functional group that reacts with the metal compound (W) and can dissolve the metal compound (W) to be used. Can be used.
Examples of the functional group that reacts with the metal compound (W) include a group having a carbon-carbon double bond such as a vinyl group, a hydroxyl group, a carboxy group, and a halogen atom as described above. When the solvent (S′1) does not have such a functional group, the metal compound (W) is stably present in the solvent (S ′), and thus the film forming ability is excellent.

In the present invention, the solvent (S′1) preferably has a boiling point of 155 ° C. or higher. By using such a solvent, the coating selectivity is improved and the resist pattern surface can be selectively coated. In addition, since the resist pattern surface can be selectively coated, an organic film such as an organic BARC formed on the substrate below the non-patterned portion of the resist pattern (the portion where no resist is present) or an organic BARC (hereinafter, these are summarized) The etching selectivity with respect to “a non-patterned substrate or the like” is also good.
Here, in this specification, “etching selection ratio” means a coating pattern and a non-pattern when etching a non-patterned substrate or the like using a resist pattern (covering pattern) coated with a metal oxide film as a mask. It means the difference in apparent etching rate between the partial substrate and the like.
Usually, when a film forming material is applied to the resist pattern surface, especially when an organic film such as organic BARC is provided on the substrate, the coating selectivity is low, and the surface of the non-patterned substrate or the like is also a metal oxide film. It will be covered with. Therefore, when etching is performed using a pattern (covering pattern) covered with a metal oxide film as a mask, etching of the non-patterned part substrate or the like is hindered by the metal oxide film, and apparently the covering pattern and the non-patterned part substrate There is a problem that a sufficient etching selectivity cannot be obtained.
However, by using the solvent (S′1) as described above, the coating selectivity is improved and the etching selectivity with respect to the non-patterned portion is improved. This is because the solvent (S′1) is almost volatilized after the film forming material containing the solvent (S′1) is applied on the pattern and before the metal compound (W) is hydrolyzed to form a film. Presumably because it remains without. That is, in a process of etching using a pattern formed on a substrate as a mask, a film forming material is applied onto a resist pattern to form a coating film, and then the solvent in the coating film contains a metal compound (W ) Is volatilized before being hydrolyzed to form a film, the metal compound (W) is physically adsorbed not only on the surface of the pattern but also on the surface of the non-patterned substrate, etc. It may be formed and the apparent etching selectivity may be reduced. On the other hand, it is presumed that by containing the solvent (S′1) having a boiling point of 155 ° C. or higher, volatilization of the solvent (S ′) is suppressed, and these problems are improved.
In particular, as will be described later, when the surface is washed (rinsed) after the film forming material is applied, the etching selectivity with respect to the non-patterned portion substrate or the like is further improved. This is because the solvent (S′1) remains with almost no volatilization until the cleaning is performed. Therefore, the metal compound (W) on the surface of the pattern, which is relatively strongly adhered by chemical adsorption or the like, is cleaned. However, the metal compound (W) on the surface of the non-patterned portion substrate or the like which is relatively weakly adhered by physical adsorption or the like is removed by washing, and as a result, a metal oxide is formed on the surface of the non-patterned portion substrate or the like It is presumed that almost no film is formed.
The boiling point of the solvent (S′1) is more preferably 160 ° C. or higher, and further preferably 165 ° C. or higher. The upper limit of the boiling point is not particularly limited, but is preferably 300 ° C. or lower and more preferably 250 ° C. or lower in consideration of applicability and the like.

The solvent (S′1) is preferably an aliphatic compound because of excellent effects of the present invention.
The aliphatic compound may be a chain compound that does not contain a ring in its structure, or may be a cyclic compound that has a ring in its structure, and a cyclic compound is preferred. The cyclic compound is preferably a hydrocarbon, and particularly preferably a saturated hydrocarbon. Examples of such cyclic compounds include monocycloalkanes, polycycloalkanes such as bicycloalkanes, tricycloalkanes, and tetracycloalkanes, and compounds in which substituents such as alkyl groups are bonded to these rings. .
Examples of the chain compound include n-hexane (boiling point: about 69 ° C.), n-heptane (boiling point: about 98 ° C.), and the like.
As a cyclic compound, the compound etc. which are represented with general formula (s'-1) mentioned later are mentioned, for example.

As the solvent (S′1), it is preferable to select a solvent having a small influence on the environment.
Examples of such a solvent include a solvent whose starting material is a natural substance.
Solvents whose starting materials are natural substances include, for example, terpene solvents obtained from plant essential oil components (for example, monocyclic monoterpenes such as p-menthane, o-menthane, m-menthane described later, and pinanes). Cyclic monoterpenes, etc.).

  Furthermore, in the present invention, since the film forming material is used to coat the resist pattern, it is preferable to select and use a solvent (S′1) that does not dissolve the resist pattern. As a result, when the coating film is formed on the resist pattern surface using the film forming material, the resist pattern shape is hardly damaged.

  Especially as a solvent (S'1), the compound (henceforth a compound (s'-1)) represented by the following general formula (s'-1) does not react with a metal compound (W), but this It is preferable in terms of excellent effects of the invention, little influence on the environment, and not dissolving the resist pattern.

［式中、Ｒ^２１〜Ｒ^２３はそれぞれ独立に水素原子、または直鎖状もしくは分岐状のアルキル基であって、Ｒ^２１〜Ｒ^２３のうち少なくとも２つはアルキル基であり、該アルキル基は、シクロヘキサン環における当該アルキル基が結合した炭素原子以外の炭素原子と結合して環を形成していてもよい。］

[Wherein, R ^{21 to} R ²³ are each independently a hydrogen atom or a linear or branched alkyl group, and at least two of R ^{21 to} R ²³ are alkyl groups, A ring may be formed by bonding to a carbon atom other than the carbon atom to which the alkyl group in the cyclohexane ring is bonded. ]

In formula (s′-1), at least two of R ^{21 to} R ²³ are linear or branched alkyl groups. That is, in the compound (s′-1), two of R ^{21 to} R ²³ may be linear or branched alkyl groups, and the other one may be a hydrogen atom, and R ^{21 to} R ²³ May be all linear or branched alkyl groups. In the present invention, two of R ^{21 to} R ²³ are preferably linear or branched alkyl groups.

The linear or branched alkyl group of R ^{21 to} R ²³ is preferably a lower alkyl group having 1 to 5 carbon atoms, and more preferably 1 to 3 carbon atoms. Specific examples include a methyl group, an ethyl group, a propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a pentyl group, an isopentyl group, and a neopentyl group. Of these, a methyl group or an isopropyl group is preferable.
At least two alkyl groups of R ^{21 to} R ²³ may be the same or different from each other.
In the present invention, at least one of R ^{21 to} R ²³ is preferably a branched alkyl group, and particularly preferably at least one is an isopropyl group.
The compound (s′-1) particularly preferably has both an isopropyl group and a methyl group.

The alkyl group of R ^{21 to} R ²³ may be bonded to a carbon atom other than the carbon atom to which the alkyl group in the cyclohexane ring is bonded to form a ring.
Here, the alkyl group is “bonded to a carbon atom other than the carbon atom to which the alkyl group in the cyclohexane ring is bonded to form a ring” as a group in which one hydrogen atom has been removed from the alkyl group ( Means that the carbon atom on the cyclohexane ring to which the alkyl group is bonded and the other carbon atom are bridged.

The bonding positions of R ^{21 to} R ²³ are not particularly limited, but at least two alkyl groups are bonded to the 1-position and 4-position (para-position) or the 1-position and 3-position (meta-position) of the cyclohexane ring, respectively. It is preferable.

Specific examples of the compound represented by the formula (s′-1) include p-menthane (boiling point: about 170 ° C.), m-menthane (boiling point: about 170 ° C.), o-menthane (boiling point: about 170 ° C.), pinane (Boiling point: about 169 ° C.). These structures are shown below.
In the present invention, in particular, the solvent (S′1) is preferably p-menthane because of the excellent effects of the present invention.

A solvent (S'1) may be used individually by 1 type, and may mix and use 2 or more types.
In the solvent (S ′), the ratio of the solvent (S′1) is preferably in the range of 50 to 100% by mass, more preferably 80 to 100% by mass, and most preferably 100% by mass.

In the present invention, the solvent (S ′) has a functional group that reacts with the solvent (S′2) other than the solvent (S′1), that is, the metal compound (W), as long as the effects of the present invention are not impaired. A solvent can also be contained.
Examples of the solvent (S′2) include alcohols such as methanol, ethanol, and propanol; aromatic compounds such as toluene, benzene, and cumene, and cumene (boiling point: about 152). ° C) is preferred.
A solvent (S'2) may be used individually by 1 type, and may be used in mixture of 2 or more types.

  The amount of the solvent (S ′) used is not particularly limited, but preferably the molar concentration in the film-forming material (the total concentration of the metal compound (W) and an organic compound described later used as necessary). Is preferably used in an amount of about 1 to 200 mM, more preferably 10 to 150 mM, and even more preferably 25 to 100 mM. A molar concentration within this range is preferable because a more uniform film can be formed.

<Optional component>
In addition to the metal compound (W) and the solvent (S ′), an optional component may be blended in the film forming material.
Examples of the optional component include organic compounds. Thereby, a composite film of a metal oxide and an organic compound can be formed.
The organic compound is not particularly limited as long as it dissolves in the solvent (S ′) described above. The dissolution here is not limited to the case where the organic compound is dissolved alone, but also includes the case where it is dissolved in a solvent such as chloroform by complexing with a metal alkoxide, such as 4-phenylazobenzoic acid.
There is no restriction | limiting in particular about the molecular weight of an organic compound.

The organic compound has a plurality of reactive groups (preferably a hydroxyl group or a carboxy group) from the viewpoint of further enhancing the strength of the coating film and the adhesion to the pattern, and is solid at room temperature (25 ° C.). It is preferable to use a material having a property.
Examples of such organic compounds include polymer compounds having a hydroxyl group or a carboxy group such as polyacrylic acid, polyvinyl alcohol, polyvinylphenol, polymethacrylic acid, and polyglutamic acid; polysaccharides such as starch, glycogen, and colominic acid; glucose, A disaccharide such as mannose, a monosaccharide; a porphyrin compound having a hydroxyl group or a carboxy group at the end, a dendrimer, or the like is preferably used.

Moreover, a cationic polymer compound can also be preferably used as the organic compound. Since metal alkoxides and metal oxides can interact anionically with the cation of the cationic polymer compound, a strong bond can be realized.
Specific examples of the cationic polymer compound include PDDA (polydimethyldiallylammonium chloride), polyethyleneimine, polylysine, chitosan, and a dendrimer having an amino group at the terminal.

These organic compounds function as a structural component for forming a thin film having high mechanical strength. Moreover, it can also serve as a functional site for imparting a function to the thin film obtained.
An organic compound can be used 1 type or in mixture of 2 or more types.
When mix | blending an organic compound, 0.1-50 mass parts is preferable with respect to 100 mass parts of metal compounds (W), and 1-20 mass parts is especially preferable.

  Moreover, you may add the unsaturated ether compound currently disclosed by Unexamined-Japanese-Patent No. 2004-315771 to the film formation material of this invention in order to improve stability with time.

In the present invention, by using such a film forming material, a uniform metal oxide film (coating film) having a high etching resistance can be formed on the resist pattern surface at a low temperature.
That is, conventionally, a chemical vapor deposition method (hereinafter sometimes referred to as a CVD method), an SOG (spin-on-glass) method, or the like is used to form a silica-based film such as a SiO ₂ film. The SOG method is generally a film containing SiO ₂ as a main component (hereinafter referred to as an SOG coating) by applying a solution (hereinafter sometimes referred to as an SOG solution) in which a silicon compound is dissolved in an organic solvent, followed by heat treatment. (See, for example, Japanese Patent Application Laid-Open No. 2003-167346, Japanese Patent Publication No. 8-3074, Japanese Patent No. 2739902, Japanese Patent No. 3228714, etc.).
A metal oxide film such as this silica-based film is said to have excellent etching resistance. However, when such a metal oxide film is formed on the resist pattern surface, there are various problems. For example, in order to obtain a high-quality metal oxide film having excellent etching resistance, for example, in the case of the CVD method or SOG method, it is necessary to bake at a high temperature of 400 ° C. or higher to form a dense metal oxide film. Such a high-temperature process has problems such as time and cost, and poor production efficiency. In addition, when the metal oxide film is coated on the resist pattern surface, it is difficult to maintain the shape of the resist pattern, for example, the resist pattern to be coated is thermally sag due to the high temperature treatment as described above.
On the other hand, according to the metal oxide film forming material described above, the metal oxide film can be formed at a relatively low temperature that can maintain the shape of the resist pattern.
Therefore, for example, when the substrate or the organic film provided on the substrate is etched using the coating pattern coated with the coating film as a mask, the shape of the coating pattern is not impaired, and it is faithful to the coating pattern. The pattern can be transferred to a substrate or an organic film. In addition, since a pattern faithful to the coating pattern can be transferred to the organic film, a pattern with a high aspect ratio can be formed. The aspect ratio is represented by the ratio of the pattern height to the width below the substrate (substrate side).
In addition, since a metal oxide film having a uniform thickness can be formed on the resist pattern surface, when the coating pattern is transferred by performing etching of the substrate or the like using the coating pattern coated with the metal oxide film as a mask, The shape of the pattern formed on the substrate or the like, the resolution, etc. are improved.
In addition, the resist pattern can be coated by low-temperature treatment (a coating film can be formed by heat treatment or a coating film can be formed without heat treatment). Since it is simple, the production efficiency can be improved and the cost can be reduced, and it can be applied to coating various resist patterns.

[Chemically amplified resist composition]
The first chemically amplified resist composition and the second chemically amplified resist composition used in the pattern forming method of the present invention are not particularly limited, and each has been proposed as a chemically amplified resist composition. Among the many chemically amplified resist compositions, it can be appropriately selected and used according to the exposure light source to be used, lithography characteristics, and the like.
Each of the first chemically amplified resist composition and the second chemically amplified resist composition may be a positive resist composition or a negative resist composition.
In the present invention, both the first chemically amplified resist composition and the second chemically amplified resist composition are preferably positive resist compositions.

The chemically amplified resist composition includes a base material component (A) whose solubility in an alkaline developer is changed by the action of an acid (hereinafter referred to as “component (A)”) and an acid generator component that generates an acid upon exposure ( B) (hereinafter referred to as “component (B)”) is generally dissolved in organic solvent (S) (hereinafter referred to as “component (S)”).
Here, the “base material component” is an organic compound having a film forming ability, and an organic compound having a molecular weight of 500 or more is preferably used. When the molecular weight of the organic compound is 500 or more, the film forming ability is improved and a nano-level pattern is easily formed.
The organic compound having a molecular weight of 500 or more is roughly classified into a low molecular weight organic compound having a molecular weight of 500 to 2000 (hereinafter referred to as a low molecular compound) and a high molecular weight resin having a molecular weight of more than 2000 (polymer). Is done. As the low molecular weight compound, a non-polymer is usually used. In the case of a resin (polymer), a polystyrene-reduced weight average molecular weight by GPC (gel permeation chromatography) is used as the “molecular weight”. Hereinafter, the term “resin” simply means a resin having a molecular weight of more than 2000.
The component (A) may be a low-molecular compound whose solubility in an alkali developer is changed by the action of an acid, or a resin whose solubility in an alkali developer is changed by the action of an acid. It may be a mixture of

As the component (A), organic compounds that are usually used as base material components for chemically amplified resists can be used singly or in combination of two or more.
As the component (A) of the chemically amplified resist composition, those having a hydrophilic group are preferable. By having a hydrophilic group, when a resist pattern is formed using the chemically amplified resist composition, a coating film having good adhesion can be formed uniformly on the resist pattern. That is, when the component (A) has a hydrophilic group, the hydrophilic group exists on the resist pattern surface. The hydrophilic group functions as a functional group (reactive group) that bonds strongly with the metal oxide film formed on the resist pattern, thereby forming a uniform high-density coating film on the resist pattern. Can be formed.
The hydrophilic group in the component (A) includes a hydroxyl group, a carboxy group, a carbonyl group (—C (O) —), an ester group (ester bond; —C (O) —O—), an amino group, and an amide group. One or more selected from the group is preferred. Of these, hydroxyl groups (particularly alcoholic hydroxyl groups or phenolic hydroxyl groups), carboxy groups, and ester groups are more preferred.
Among these, a carboxy group, an alcoholic hydroxyl group, and a phenolic hydroxyl group are particularly preferable because they easily form a coating film on the pattern surface. In addition, a pattern with small line edge roughness (unevenness on the pattern side wall) can be formed at the nano level, which is preferable.

The content ratio of the hydrophilic group in the component (A) affects the amount per unit area of the hydrophilic group present on the pattern surface. Therefore, the adhesion and density of the coating film formed on the pattern can be affected.
When the component (A) is a low molecular compound, the component (A) preferably has 1 to 20 equivalents of hydrophilic groups per molecule, more preferably 2 to 10 equivalents. Here, “having 1 to 20 equivalents of hydrophilic group per molecule” means that 1 to 20 hydrophilic groups are present in one molecule.
When the component (A) is a resin, the component (A) preferably has a hydrophilic group of 0.2 equivalent or more, more preferably 0.5 to 0.8 equivalent, and still more preferably 0.6 to 0. A range of .75 equivalents. This is because if the resin is composed of a structural unit having a hydrophilic group and other structural units, the former structural unit is 20 mol% or more, more preferably 50 to 80 mol%, still more preferably 60 mol% to It means 75 mol%.
In the present specification, “structural unit” and “unit” mean a monomer unit constituting a resin (polymer, copolymer).

When the chemically amplified resist composition is a negative resist composition, as the component (A), a base material component soluble in an alkali developer is used, and a crosslinking agent is further blended.
In such a negative resist composition, when an acid is generated from the component (B) by exposure, crosslinking occurs between the component (A) and the crosslinking agent by the action of the acid, and the component (A) becomes an alkaline developer. On the other hand, it changes from soluble to hardly soluble. Therefore, in the formation of the resist pattern, when the resist film obtained by applying the negative resist composition on the support is selectively exposed, the exposed portion turns into slightly soluble in the alkali developer. The unexposed portion remains soluble in the alkali developer and does not change, so that alkali development can be performed.
As the component (A) of the negative resist composition, a resin that is soluble in an alkali developer (hereinafter referred to as an alkali-soluble resin) is usually used.
As the alkali-soluble resin, a resin having a unit derived from at least one selected from α- (hydroxyalkyl) acrylic acid or a lower alkyl ester of α- (hydroxyalkyl) acrylic acid is preferable because of less swelling. A resist pattern can be formed, which is preferable. Α- (Hydroxyalkyl) acrylic acid includes acrylic acid in which a hydrogen atom is bonded to the α-position carbon atom to which the carboxy group is bonded, and a hydroxyalkyl group (preferably having 1 carbon atom) in the α-position carbon atom. One or both of [alpha] -hydroxyalkylacrylic acids to which (5) hydroxyalkyl groups) are attached.
As the crosslinking agent, for example, it is usually preferable to use an amino crosslinking agent such as glycoluril having a methylol group or an alkoxymethyl group because a good resist pattern with less swelling can be formed.
It is preferable that the compounding quantity of a crosslinking agent is 1-50 mass parts with respect to 100 mass parts of alkali-soluble resin.

When the chemically amplified resist composition is a positive resist composition, as the component (A), there is a base material component having an acid dissociable, dissolution inhibiting group and increasing the solubility in an alkali developer by the action of an acid. Used.
Such a positive resist composition is hardly soluble in an alkali developer before exposure. When an acid is generated from the component (B) by exposure at the time of resist pattern formation, an acid dissociable dissolution inhibiting group is generated by the action of the acid. Dissociates, and the component (A) becomes soluble in an alkaline developer. Therefore, in the formation of the resist pattern, when the resist film obtained by applying the positive resist composition on the substrate is selectively exposed, the exposed portion turns soluble in an alkali developer, while Since the exposed portion remains hardly soluble in an alkali developer, it does not change, so that alkali development can be performed.

As the (A) component of the positive resist composition, those having a hydrophilic group and an acid dissociable, dissolution inhibiting group are preferred, and the following (A-1) component and / or (A-2) component are more preferred. The hydrophilic group may also serve as an acid dissociable, dissolution inhibiting group.
Component (A-1): a resin having a hydrophilic group and an acid dissociable, dissolution inhibiting group.
Component (A-2): a low molecular compound having a hydrophilic group and an acid dissociable, dissolution inhibiting group.
Hereinafter, preferred embodiments of the component (A-1) and the component (A-2) will be described more specifically.

[(A-1) component]
As the component (A-1), a resin having a structural unit having a hydrophilic group and a structural unit having an acid dissociable, dissolution inhibiting group is preferable.
The proportion of the structural unit having the hydrophilic group in the resin is preferably 20 to 80 mol%, more preferably 20 to 70 mol%, based on the total amount of all the structural units constituting the resin. 20 to 60 mol% is more preferable.
The proportion of the structural unit having the acid dissociable, dissolution inhibiting group in the resin is preferably 20 to 80 mol% with respect to the total amount of all structural units constituting the resin. Is more preferable, and 30 to 60 mol% is more preferable.
Preferably, the structural unit having a hydrophilic group is a structural unit having a carboxy group, an alcoholic hydroxyl group or a phenolic hydroxyl group, more preferably an acrylic acid, methacrylic acid or an alcoholic hydroxyl group (α-lower alkyl). A unit derived from an acrylate ester and hydroxystyrene.

More specifically, the component (A-1) is derived from a novolak resin having a hydrophilic group and an acid dissociable, dissolution inhibiting group, a hydroxystyrene resin, an (α-lower alkyl) acrylate resin, and hydroxystyrene. And a copolymer resin containing a structural unit derived from an (α-lower alkyl) acrylic acid ester are preferably used.
In this specification, “(α-lower alkyl) acrylic acid” refers to one or both of acrylic acid (CH ₂ ═CH—COOH) and α-lower alkylacrylic acid. α-Lower alkyl acrylic acid refers to one in which a hydrogen atom bonded to a carbon atom to which a carbonyl group in acrylic acid is bonded is substituted with a lower alkyl group. “(Α-Lower alkyl) acrylic acid ester” is an ester derivative of “(α-lower alkyl) acrylic acid” and represents one or both of acrylic acid ester and α-lower alkyl acrylic acid ester.
The “structural unit derived from (α-lower alkyl) acrylic acid ester” is a structural unit formed by cleavage of an ethylenic double bond of (α-lower alkyl) acrylic acid ester. -Lower alkyl) acrylate structural unit. “(Α-lower alkyl) acrylate” refers to one or both of acrylate and α-lower alkyl acrylate.
The “structural unit derived from hydroxystyrene” is a structural unit formed by cleaving an ethylenic double bond of hydroxystyrene or α-lower alkylhydroxystyrene, and may hereinafter be referred to as a hydroxystyrene unit. “Α-lower alkylhydroxystyrene” indicates that the lower alkyl group is bonded to the carbon atom to which the phenyl group is bonded.
In the “structural unit derived from an α-lower alkyl acrylate ester” and the “structural unit derived from an α-lower alkylhydroxystyrene”, the lower alkyl group bonded to the α-position has 1 to 5 carbon atoms. An alkyl group, preferably a linear or branched alkyl group, methyl group, ethyl group, propyl group, isopropyl group, n-butyl group, isobutyl group, tert-butyl group, pentyl group, isopentyl group, neopentyl group Etc. Industrially, a methyl group is preferable.
In the lower alkyl group, part or all of the hydrogen atoms may be substituted with a halogen atom. Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom, and a fluorine atom is particularly preferable.

The resin component suitable as the component (A-1) is not particularly limited. For example, a unit having a phenolic hydroxyl group such as the following structural unit (a1), the following structural unit (a2) and the following structural unit A structural unit having at least one acid dissociable, dissolution inhibiting group selected from the group consisting of units (a3), and hardly soluble in an alkali developer such as structural unit (a4), which is used as necessary. The resin component which has a structural unit of (Hereinafter, it may be called (A-11) component.).
In the component (A-11), cleavage occurs in the structural unit (a2) and / or the structural unit (a3) by the action of the acid generated from the acid generator upon exposure. On the other hand, in a resin that is hardly soluble, the solubility in an alkali developer increases. As a result, a chemically amplified positive pattern can be formed by exposure and development.

..Structural unit (a1)
The structural unit (a1) is a unit having a phenolic hydroxyl group, and is preferably a unit derived from hydroxystyrene represented by the following general formula (I).

（式中、Ｒは水素原子または低級アルキル基を示す。）

(In the formula, R represents a hydrogen atom or a lower alkyl group.)

R is a hydrogen atom or a lower alkyl group. The lower alkyl group is as described above, and a hydrogen atom or a methyl group is particularly preferable. The description of R is the same below.
The bonding position of —OH to the benzene ring is not particularly limited, but the position 4 (para position) described in the formula is preferred.
The structural unit (a1) is preferably contained in an amount of 40 to 80 mol%, preferably 50 to 75 mol% in the component (A-11) from the viewpoint of forming a pattern. By setting it as 40 mol% or more, the solubility with respect to an alkali developing solution can be improved, and the improvement effect of a pattern shape is also acquired. The balance with other structural units can be taken by setting it as 80 mol% or less.
Moreover, from the point that a coating film is formed on the pattern, the structural unit (a1) is preferably contained in the component (A-11) in an amount of 50 mol% or more, more preferably 60 mol% or more. More preferably, it is 75 mol% or more. Although an upper limit is not specifically limited, It is 80 mol% or less. Within the above range, a good coating film can be formed on the pattern due to the presence of the phenolic hydroxyl group, and a pattern with a good shape can be obtained. In addition, the adhesion between the pattern and the coating film is improved.

..Structural unit (a2)
The structural unit (a2) is a structural unit having an acid dissociable, dissolution inhibiting group, and is represented by the following general formula (II).

（式中、Ｒは上記と同じであり、Ｘは酸解離性溶解抑制基を示す。）

(In the formula, R is the same as above, and X represents an acid dissociable, dissolution inhibiting group.)

The acid dissociable, dissolution inhibiting group X is an alkyl group having a tertiary carbon atom, and the tertiary carbon atom of the tertiary alkyl group is bonded to the ester group [—C (O) O—]. Examples thereof include an acid-dissolving dissolution inhibiting group, a cyclic acetal group such as a tetrahydropyranyl group and a tetrahydrofuranyl group.
As such an acid dissociable, dissolution inhibiting group X, for example, those other than those described above can be arbitrarily used from among those used in a chemically amplified positive resist composition.

  As the structural unit (a2), for example, those represented by general formula (III) shown below are preferred.

In the formula, R is the same as above, and R ¹¹ , R ¹² , and R ¹³ are each independently a lower alkyl group (which may be linear or branched. Preferably, the number of carbon atoms is 1 to 5). It is. Or, among R ¹¹ , R ¹² and R ¹³ , R ¹¹ may be a lower alkyl group, and R ¹² and R ¹³ may be bonded to form a monocyclic or polycyclic aliphatic cyclic group. . The aliphatic cyclic group preferably has 5 to 12 carbon atoms.
When R ¹¹ , R ¹² , and R ¹³ do not have an aliphatic cyclic group, for example, it is preferable that R ¹¹ , R ¹² , and R ¹³ are all methyl groups.
In the case where any of R ¹¹ , R ¹² and R ¹³ has an aliphatic cyclic group, when the aliphatic cyclic group is a monocyclic aliphatic cyclic group, as the structural unit (a2), for example, cyclopentyl And those having a cyclohexyl group are preferred.
When the aliphatic cyclic group is a polycyclic alicyclic group, preferred examples of the structural unit (a2) include those represented by the following general formula (IV).

［式中、Ｒは上記と同じであり、Ｒ^１４は低級アルキル基（直鎖、分岐鎖のいずれでもよい。好ましくは炭素数は１〜５である。）］

[Wherein, R is the same as described above, and R ¹⁴ is a lower alkyl group (which may be linear or branched, preferably has 1 to 5 carbon atoms)]

  Moreover, what is represented by the following general formula (V) is preferable as what has an acid dissociable dissolution inhibiting group containing a polycyclic aliphatic cyclic group.

［式中、Ｒは上記と同じであり、Ｒ^１５、Ｒ^１６は、それぞれ独立に低級アルキル基（直鎖、分岐鎖のいずれでもよい。好ましくは炭素数は１〜５である。）である。］

[Wherein, R is the same as defined above, and R ¹⁵ and R ¹⁶ each independently represent a lower alkyl group (which may be either a straight chain or a branched chain, preferably has 1 to 5 carbon atoms). . ]

  In the component (A-11), the proportion of the structural unit (a2) is preferably 5 to 50 mol%, more preferably 10 to 40 mol%, and still more preferably 10 to 35 mol%.

..Structural unit (a3)
The structural unit (a3) is a structural unit having an acid dissociable, dissolution inhibiting group, and is represented by the following general formula (VI).

（式中、Ｒは上記と同じであり、Ｘ’は酸解離性溶解抑制基を示す。）

(In the formula, R is the same as above, and X ′ represents an acid dissociable, dissolution inhibiting group.)

Examples of the acid dissociable, dissolution inhibiting group X ′ include tertiary alkyloxycarbonyl groups such as tert-butyloxycarbonyl group and tert-pentyloxycarbonyl group; tert-butyloxycarbonylmethyl group, tert-butyloxycarbonylethyl group Tertiary alkyloxycarbonylalkyl groups such as: tertiary alkyl groups such as tert-butyl and tert-pentyl groups; cyclic acetal groups such as tetrahydropyranyl and tetrahydrofuranyl groups; ethoxyethyl groups and methoxypropyl groups And the like, and the like.
Of these, a tert-butyloxycarbonyl group, a tert-butyloxycarbonylmethyl group, a tert-butyl group, a tetrahydropyranyl group, and an ethoxyethyl group are preferable.
As the acid dissociable, dissolution inhibiting group X ′, those other than those described above can be arbitrarily used from among those used in, for example, a chemically amplified positive resist composition.
In the general formula (VI), the bonding position of the group (—OX ′) bonded to the benzene ring is not particularly limited, but the position 4 (para position) shown in the formula is preferable.

  In the component (A-11), the proportion of the structural unit (a3) is preferably 5 to 50 mol%, more preferably 10 to 40 mol%, and still more preferably 10 to 35 mol%.

..Structural unit (a4)
The structural unit (a4) is a unit that is hardly soluble in an alkali developer and is represented by the following general formula (VII).

（式中、Ｒは上記と同じであり、Ｒ^４’は低級アルキル基を示し、ｎ’は０または１〜３の整数を示す。）

(In the formula, R is the same as above, R ^{4 ′} represents a lower alkyl group, and n ′ represents 0 or an integer of 1 to 3).

The lower alkyl group for R ^{4 ′} may be either a straight chain or branched chain, and preferably has 1 to 5 carbon atoms.
n ′ represents 0 or an integer of 1 to 3, and is preferably 0.

  In the component (A-11), the proportion of the structural unit (a4) is preferably 1 to 40 mol%, more preferably 5 to 25 mol%. By setting it to 1 mol% or more, the effect of improving the shape (particularly, improving film loss) is enhanced, and by setting it to 40 mol% or less, it is possible to balance with other structural units.

In the component (A-11), while the structural unit (a1) and at least one selected from the group consisting of the structural unit (a2) and the structural unit (a3) are essential, the structural unit (a4) is arbitrarily selected. May be included. Further, a copolymer having all of these units may be used, or a mixture of polymers having one or more of these units (for example, a polymer or copolymer having a structural unit (a1), A polymer or a mixture having a structural unit (a2) may be used. Or these may be combined.
Further, the component (A-11) can optionally contain components other than the structural units (a1), (a2), (a3), and (a4), but the total ratio of these structural units is 80. It is preferably at least mol%, more preferably at least 90 mol%, most preferably 100 mol%.

As the component (A-11), in particular, “any one of the copolymers having the structural units (a1) and (a3), or a mixture of two or more of the copolymers” or “configuration An embodiment in which any one of the copolymers having units (a1), (a2) and (a4), or a mixture of two or more of the copolymers is used or mixed, has lithography characteristics, heat resistance It is most preferable because of its excellent properties.
In particular, a mixture of polyhydroxystyrene protected with a tertiary alkyloxycarbonyl group and polyhydroxystyrene protected with a 1-alkoxyalkyl group is preferred. When such mixing is performed, the mixing ratio (mass ratio) of each polymer (polyhydroxystyrene protected with a tertiary alkyloxycarbonyl group / 1-polyhydroxystyrene protected with 1-alkoxyalkyl group) is, for example, 1/9 to The ratio is 9/1, preferably 2/8 to 8/2, and more preferably 2/8 to 5/5.

In addition to the component (A-11), examples of the resin component suitable as the component (A-1) include (α-lower alkyl) acrylate resin (hereinafter referred to as component (A-12)).
As the component (A-12), a resin having a structural unit (a5) derived from an (α-lower alkyl) acrylate ester containing an acid dissociable, dissolution inhibiting group is preferable. The α-lower alkyl group is the same as described above.
The acid dissociable, dissolution inhibiting group of the structural unit (a5) has an alkali dissolution inhibiting property that makes the entire component (A-12) before exposure difficult to dissolve in an alkali developer, and at the same time, the component (B) after exposure. It is a group that is dissociated by the action of an acid generated from the above and changes the entire component (A-12) to be soluble in an alkali developer.
In the component (A-12), when the acid dissociable, dissolution inhibiting group in the structural unit (a5) is dissociated by the acid generated from the component (B), a carboxylic acid is generated. Due to the presence of the generated carboxylic acid, the adhesion with the coating film formed on the resist pattern is improved.

As the acid dissociable, dissolution inhibiting group, for example, a resin for resist composition of ArF excimer laser can be appropriately selected from those proposed in large numbers. In general, a group that forms a cyclic or chain tertiary alkyl ester with a carboxy group of (α-lower alkyl) acrylic acid, or a cyclic or chain alkoxyalkyl group is widely known.
Here, the “group that forms a tertiary alkyl ester” is a group that forms an ester by substituting the hydrogen atom of the carboxy group of acrylic acid. That is, a structure in which the tertiary carbon atom of a chain-like or cyclic tertiary alkyl group is bonded to the oxygen atom at the terminal of the carbonyloxy group [—C (O) —O—] of the acrylate ester. In this tertiary alkyl ester, when an acid acts, a bond is cut between an oxygen atom and a tertiary carbon atom.
The tertiary alkyl group is an alkyl group having a tertiary carbon atom.
Examples of the group that forms a chain-like tertiary alkyl ester include a tert-butyl group and a tert-pentyl group.
Examples of the group that forms a cyclic tertiary alkyl ester include those exemplified in the “acid dissociable, dissolution inhibiting group containing an alicyclic group” described later.

The “cyclic or chain alkoxyalkyl group” is substituted with a hydrogen atom of a carboxy group to form an ester. That is, a structure is formed in which the alkoxyalkyl group is bonded to the terminal oxygen atom of the carbonyloxy group [—C (O) —O—] of the acrylate ester. In such a structure, the bond between the oxygen atom and the alkoxyalkyl group is broken by the action of an acid.
Examples of such cyclic or chain alkoxyalkyl groups include 1-methoxymethyl group, 1-ethoxyethyl group, 1-isopropoxyethyl, 1-cyclohexyloxyethyl group, 2-adamantoxymethyl group, 1-methyladamant Examples thereof include a xymethyl group, a 4-oxo-2-adamantoxymethyl group, a 1-adamantoxyethyl group, and a 2-adamantoxyethyl group.

As the structural unit (a5), a structural unit containing an acid dissociable, dissolution inhibiting group containing a cyclic group, particularly an aliphatic cyclic group, is preferred.
The aliphatic cyclic group may be monocyclic or polycyclic, and can be appropriately selected and used from among many proposed, for example, ArF resists. From the viewpoint of etching resistance, a polycyclic alicyclic group is preferred. The alicyclic group is preferably a hydrocarbon group, and particularly preferably a saturated hydrocarbon group (alicyclic group).
Examples of the monocyclic alicyclic group include groups in which one hydrogen atom has been removed from a cycloalkane. Examples of the polycyclic alicyclic group include groups in which one hydrogen atom has been removed from bicycloalkane, tricycloalkane, tetracycloalkane and the like.
Specifically, examples of the monocyclic alicyclic group include a cyclopentyl group and a cyclohexyl group. Examples of the polycyclic alicyclic group include groups in which one hydrogen atom has been removed from a polycycloalkane such as adamantane, norbornane, isobornane, tricyclodecane, and tetracyclododecane.
Among these, an adamantyl group obtained by removing one hydrogen atom from adamantane, a norbornyl group obtained by removing one hydrogen atom from norbornane, a tricyclodecanyl group obtained by removing one hydrogen atom from tricyclodecane, and tetracyclo A tetracyclododecanyl group obtained by removing one hydrogen atom from dodecane is preferred industrially.

More specifically, the structural unit (a5) is preferably at least one selected from the following general formulas (I ′) to (III ′).
In addition, a unit derived from an (α-lower alkyl) acrylic acid ester having a cyclic alkoxyalkyl group as described above, specifically a 2-adamantoxymethyl group, 1-methyladamant Aliphatic polycyclic alkyloxy lower alkyl (α which may have a substituent such as xymethyl group, 4-oxo-2-adamantoxymethyl group, 1-adamantoxyethyl group, 2-adamantoxyethyl group, etc. -Lower alkyl) It is preferably at least one selected from units derived from acrylic acid esters.

［式（Ｉ’）中、Ｒは上記と同じであり、Ｒ^１は低級アルキル基である。］

[In the formula (I ′), R is the same as above, and R ¹ is a lower alkyl group. ]

［式（ＩＩ’）中、Ｒは上記と同じであり、Ｒ^２及びＲ^３はそれぞれ独立に低級アルキル基である。］

[In formula (II ′), R is as defined above, and R ² and R ³ each independently represents a lower alkyl group. ]

［式（ＩＩＩ’）中、Ｒは上記と同じであり、Ｒ^４は第３級アルキル基である。］

[In the formula (III ′), R is the same as above, and R ⁴ is a tertiary alkyl group. ]

In formulas (I ′) to (III ′), the hydrogen atom or lower alkyl group of R is the same as described above for the hydrogen atom or lower alkyl group bonded to the α-position of the acrylate ester.
The lower alkyl group for R ¹ is preferably a linear or branched alkyl group having 1 to 5 carbon atoms, and specifically includes a methyl group, an ethyl group, a propyl group, an isopropyl group, an n-butyl group, and an isobutyl group. , A pentyl group, an isopentyl group, a neopentyl group, and the like. Among these, a methyl group and an ethyl group are preferable because they are easily available industrially.
The lower alkyl group for R ² and R ³ is preferably each independently a linear or branched alkyl group having 1 to 5 carbon atoms. Among them, when R ² and R ³ are both methyl groups is preferred industrially. Specific examples include structural units derived from 2- (1-adamantyl) -2-propyl acrylate.

R ⁴ is a chain-like tertiary alkyl group or a cyclic tertiary alkyl group. Examples of the chain-like tertiary alkyl group include a tert-butyl group and a tert-pentyl group, and the tert-butyl group is industrially preferable.
The cyclic tertiary alkyl group is the same as that exemplified in the aforementioned “acid dissociable, dissolution inhibiting group containing an aliphatic cyclic group”, and includes a 2-methyl-2-adamantyl group, 2-ethyl- Examples include 2-adamantyl group, 2- (1-adamantyl) -2-propyl group, 1-ethylcyclohexyl group, 1-ethylcyclopentyl group, 1-methylcyclohexyl group, 1-methylcyclopentyl group and the like.
The group —COOR ⁴ may be bonded to the 3 or 4 position of the tetracyclododecanyl group shown in the formula, but the bonding position cannot be specified. Similarly, the carboxy group residue of the acrylate structural unit may be bonded to the position 8 or 9 shown in the formula.

The structural unit (a5) can be used alone or in combination of two or more.
In the component (A-12), the proportion of the structural unit (a5) is preferably 20 to 60 mol%, and preferably 30 to 50 mol based on the total of all the structural units constituting the component (A-12). % Is more preferable, and 35 to 45 mol% is most preferable. A pattern can be obtained by setting it to the lower limit value or more, and balancing with other structural units can be achieved by setting it to the upper limit value or less.

In addition to the structural unit (a5), the component (A-12) preferably further has a structural unit (a6) derived from an acrylate ester having a lactone ring. The structural unit (a6) is effective in increasing the adhesion of the resist film to the substrate and increasing the hydrophilicity with the developer. In addition, a coating film having high adhesion to the pattern can be formed.
In the structural unit (a6), a lower alkyl group or a hydrogen atom is bonded to the α-position carbon atom. The lower alkyl group bonded to the α-position carbon atom is the same as described for the structural unit (a5), and is preferably a methyl group.
Examples of the structural unit (a6) include a structural unit in which a monocyclic group consisting of a lactone ring or a polycyclic cyclic group having a lactone ring is bonded to the ester side chain portion of the acrylate ester. At this time, the lactone ring indicates one ring containing an —O—C (O) — structure, and this is counted as the first ring. Therefore, here, in the case of only a lactone ring, it is called a monocyclic group, and when it has another ring structure, it is called a polycyclic group regardless of the structure.
Examples of the structural unit (a6) include a monocyclic group obtained by removing one hydrogen atom from γ-butyrolactone and a polycyclic group obtained by removing one hydrogen atom from a lactone ring-containing bicycloalkane. It is done.
More specifically, the structural unit (a6) is preferably at least one selected from, for example, the following general formulas (IV ′) to (VII ′).

［式（ＩＶ’）中、Ｒは上記と同じであり、Ｒ^５、Ｒ^６は、それぞれ独立に、水素原子または低級アルキル基である。］

[In formula (IV ′), R is the same as defined above, and R ⁵ and R ⁶ each independently represent a hydrogen atom or a lower alkyl group. ]

［式（Ｖ’）中、Ｒは上記と同じであり、ｍは０または１である。］

[In the formula (V ′), R is the same as described above, and m is 0 or 1. ]

［式（ＶＩ’）中、Ｒは上記と同じである。］

[In formula (VI ′), R is the same as defined above. ]

［式（ＶＩＩ’）中、Ｒは上記と同じである。］

[In the formula (VII ′), R is the same as above. ]

In formula (IV ′), R ⁵ and R ⁶ are each independently a hydrogen atom or a lower alkyl group, preferably a hydrogen atom. In R ⁵ and R ⁶ , the lower alkyl group is preferably a linear or branched alkyl group having 1 to 5 carbon atoms, and includes a methyl group, an ethyl group, a propyl group, an isopropyl group, an n-butyl group, and an isobutyl group. Tert-butyl group, pentyl group, isopentyl group, neopentyl group and the like. Industrially, a methyl group is preferable.

Among the structural units represented by the general formulas (IV ′) to (VII ′), the structural unit represented by (IV ′) is inexpensive and industrially preferable, and among the structural units represented by (IV ′). R is a methyl group, R ⁵ and R ⁶ are hydrogen atoms, and the position of the ester bond between the methacrylic acid ester and γ-butyrolactone is α-methacryloyloxy-γ-butyrolactone, which is the α-position on the lactone ring. Most preferred.
The structural unit (a6) can be used alone or in combination of two or more.
In the component (A-12), the proportion of the structural unit (a6) is preferably 20 to 60 mol%, more preferably 20 to 50 mol%, based on the total of all the structural units constituting the component (A-12). Preferably, 30 to 45 mol% is most preferable. Lithographic characteristics are improved by setting the value to the lower limit value or more, and balance with other structural units can be achieved by setting the upper limit value or less.

The component (A-12) is derived from an acrylate ester containing a polar group-containing polycyclic group, in addition to the structural unit (a5) or in addition to the structural units (a5) and (a6). It is preferable to have the structural unit (a7).
By the structural unit (a7), the hydrophilicity of the entire component (A-12) is increased, the affinity with the developer is increased, the solubility in the alkaline developer in the exposed area is improved, and the resolution is improved. Contribute. Moreover, the adhesiveness of the resist pattern formed using the said resist composition and the coating film formed on this resist pattern surface improves.
In the structural unit (a7), a lower alkyl group or a hydrogen atom is bonded to the α-position carbon atom. The lower alkyl group bonded to the α-position carbon atom is the same as described for the structural unit (a5), and is preferably a methyl group.
Examples of the polar group include a hydroxyl group, a cyano group, a carboxy group, and an amino group, and a hydroxyl group is particularly preferable.
As the polycyclic group, among the aliphatic cyclic groups exemplified in the “acid dissociable, dissolution inhibiting group containing an aliphatic cyclic group” which is the structural unit (a5), a polycyclic group is appropriately selected. It can be selected and used.
The structural unit (a7) is preferably at least one selected from the following general formulas (VIII ′) to (IX ′).

［式（ＶＩＩＩ’）中、Ｒは上記と同じであり、ｎは１〜３の整数である。］

[In formula (VIII ′), R is the same as above, and n is an integer of 1 to 3. ]

R in the formula (VIII ′) is the same as R in the above formulas (I ′) to (III ′).
Among these, those in which n is 1 and the hydroxyl group is bonded to the 3-position of the adamantyl group are preferable.

［式（ＩＸ’）中、Ｒは上記と同じであり、ｋは１〜３の整数である。］

[In formula (IX ′), R is the same as defined above, and k is an integer of 1 to 3. ]

  Among these, those in which k is 1 are preferable. Moreover, it is preferable that the cyano group has couple | bonded with 5-position or 6-position of the norbornyl group.

The structural unit (a7) can be used alone or in combination of two or more.
In the component (A-12), the proportion of the structural unit (a7) is preferably 10 to 50 mol%, more preferably 15 to 40 mol%, based on the total of all structural units constituting the component (A-12). Preferably, 20 to 35 mol% is more preferable. Lithographic characteristics are improved by setting the value to the lower limit value or more, and balance with other structural units can be achieved by setting the upper limit value or less.

  In the component (A-12), the total of these structural units (a5) to (a7) is 70 to 100 mol% with respect to the total of all the structural units constituting the component (A-12). Preferably, it is 80-100 mol%.

The component (A-12) may contain a structural unit (a8) other than the structural units (a5) to (a7).
The structural unit (a8) is not particularly limited as long as it is another structural unit that is not classified into the structural units (a5) to (a7).
As the structural unit (a8), for example, a structural unit containing a polycyclic aliphatic hydrocarbon group and derived from an (α-lower alkyl) acrylate ester is preferable. The polycyclic aliphatic hydrocarbon group is appropriately selected from, for example, polycyclic ones among the aliphatic cyclic groups exemplified in the aforementioned “acid dissociable, dissolution inhibiting group containing an aliphatic cyclic group”. Can be used. In particular, at least one selected from a tricyclodecanyl group, an adamantyl group, a tetracyclododecanyl group, a norbornyl group, and an isobornyl group is preferable in terms of industrial availability. The structural unit (a8) is most preferably a non-acid dissociable group.
Specific examples of the structural unit (a8) include the following structures (X ′) to (XII ′).

（式中、Ｒは上記と同じである。）

(In the formula, R is the same as above.)

（式中、Ｒは上記と同じである。）

(In the formula, R is the same as above.)

（式中、Ｒは上記と同じである。）

(In the formula, R is the same as above.)

  In the case of having the structural unit (a8), the proportion of the structural unit (a8) in the component (A-12) is 1 to 25 mol% based on the total of all the structural units constituting the component (A-12). Preferably, 5 to 20 mol% is more preferable.

  The component (A-12) is preferably a copolymer having at least the structural units (a5), (a6) and (a7). Examples of such a copolymer include a copolymer composed of the structural units (a5), (a6) and (a7), and a copolymer composed of the structural units (a5), (a6), (a7) and (a8). A polymer etc. can be illustrated.

  The component (A-1) can be obtained by polymerizing the monomer related to the structural unit by a known method. For example, the monomer related to each structural unit can be obtained by polymerizing by a known radical polymerization using a radical polymerization initiator such as azobisisobutyronitrile (AIBN).

  The component (A-1) is preferably 30000 or less, more preferably 20000 or less, and preferably 12000 or less, in terms of mass average molecular weight (polystyrene conversion mass average molecular weight by gel permeation chromatography, hereinafter the same). Further preferred. The lower limit may be more than 2000, and is preferably 4000 or more, and more preferably 5000 or more in terms of suppressing pattern collapse and improving resolution.

[(A-2) component]
The component (A-2) has a molecular weight of 500 or more and 2000 or less, has a hydrophilic group, and has an acid dissociable, dissolution inhibiting group X or X as exemplified in the description of the component (A-1). Low molecular weight compounds having 'are preferred. Specific examples include those obtained by substituting a part of the hydrogen atoms of the hydroxyl group of the compound having a plurality of phenol skeletons with the acid dissociable, dissolution inhibiting group X or X ′.
The component (A-2) contains, for example, a part of the hydrogen atom of the hydroxyl group of a low molecular weight phenol compound known as a sensitizer or heat resistance improver for non-chemically amplified g-line or i-line resists. Those substituted with a dissociable, dissolution inhibiting group are preferred and can be arbitrarily used.

Examples of such low molecular weight phenol compounds include the following.
Bis (4-hydroxyphenyl) methane, bis (2,3,4-trihydroxyphenyl) methane, 2- (4-hydroxyphenyl) -2- (4′-hydroxyphenyl) propane, 2- (2,3,3) 4-trihydroxyphenyl) -2- (2 ′, 3 ′, 4′-trihydroxyphenyl) propane, tris (4-hydroxyphenyl) methane, bis (4-hydroxy-3,5-dimethylphenyl) -2- Hydroxyphenylmethane, bis (4-hydroxy-2,5-dimethylphenyl) -2-hydroxyphenylmethane, bis (4-hydroxy-3,5-dimethylphenyl) -3,4-dihydroxyphenylmethane, bis (4- Hydroxy-2,5-dimethylphenyl) -3,4-dihydroxyphenylmethane, bis (4-hydroxy-3-methylphenol) Nyl) -3,4-dihydroxyphenylmethane, bis (3-cyclohexyl-4-hydroxy-6-methylphenyl) -4-hydroxyphenylmethane, bis (3-cyclohexyl-4-hydroxy-6-methylphenyl) -3 , 4-dihydroxyphenylmethane, 1- [1- (4-hydroxyphenyl) isopropyl] -4- [1,1-bis (4-hydroxyphenyl) ethyl] benzene, phenol, m-cresol, p-cresol or xylenol And 2,3,4 nuclei of formalin condensates of phenols and the like. Of course, it is not limited to these.
The acid dissociable, dissolution inhibiting group is not particularly limited, and examples thereof include those described above.

<(B) component>
As the component (B), any conventionally known acid generator for chemically amplified resists can be appropriately selected and used. Examples of such acid generators include onium salt acid generators such as iodonium salts and sulfonium salts, oxime sulfonate acid generators, bisalkyl or bisarylsulfonyldiazomethanes, and poly (bissulfonyl) diazomethanes. There are various known diazomethane acid generators, nitrobenzyl sulfonate acid generators, imino sulfonate acid generators, disulfone acid generators, and the like.

  Specific examples of the onium salt-based acid generator include diphenyliodonium trifluoromethanesulfonate, (4-methoxyphenyl) phenyliodonium trifluoromethanesulfonate, bis (p-tert-butylphenyl) iodonium trifluoromethanesulfonate, and triphenylsulfonium trifluoromethanesulfonate. (4-methoxyphenyl) diphenylsulfonium trifluoromethanesulfonate, (4-methylphenyl) diphenylsulfonium nonafluorobutanesulfonate, (p-tert-butylphenyl) diphenylsulfonium trifluoromethanesulfonate, diphenyliodonium nonafluorobutanesulfonate, bis (p -Tert-Butylphenyl) iodonium nonafluorobutans Honeto include triphenylsulfonium nonafluorobutanesulfonate. Of these, onium salts having a fluorinated alkyl sulfonate ion as an anion are preferable.

  Examples of oxime sulfonate compounds include α- (methylsulfonyloxyimino) -phenylacetonitrile, α- (methylsulfonyloxyimino) -p-methoxyphenylacetonitrile, α- (trifluoromethylsulfonyloxyimino) -phenylacetonitrile, α -(Trifluoromethylsulfonyloxyimino) -p-methoxyphenylacetonitrile, α- (ethylsulfonyloxyimino) -p-methoxyphenylacetonitrile, α- (propylsulfonyloxyimino) -p-methylphenylacetonitrile, α- (methyl Sulfonyloxyimino) -p-bromophenylacetonitrile and the like. Of these, α- (methylsulfonyloxyimino) -p-methoxyphenylacetonitrile is preferred.

  Specific examples of the diazomethane acid generator include bis (isopropylsulfonyl) diazomethane, bis (p-toluenesulfonyl) diazomethane, bis (1,1-dimethylethylsulfonyl) diazomethane, bis (cyclohexylsulfonyl) diazomethane, bis (2, 4-dimethylphenylsulfonyl) diazomethane and the like.

As the component (B), one type of acid generator may be used alone, or two or more types may be used in combination.
(B) The usage-amount of a component becomes like this. Preferably it is 1-20 mass parts with respect to 100 mass parts of (A) component, More preferably, you may be 2-10 mass parts. By setting it to be equal to or higher than the lower limit value of the above range, sufficient pattern formation is performed.

<Optional component>
The chemical amplification resist composition is further mixed with a nitrogen-containing organic compound (D) (hereinafter referred to as the component (D)) as an optional component in order to improve the pattern shape, the stability over time and the like. Can do.
Since a wide variety of components (D) have already been proposed, any known one may be used, but amines, particularly secondary lower aliphatic amines and tertiary lower aliphatic amines are preferred. .
Here, the lower aliphatic amine refers to an alkyl or alkyl alcohol amine having 5 or less carbon atoms, and examples of the secondary and tertiary amines include trimethylamine, diethylamine, triethylamine, di-n-propylamine, Tri-n-propylamine, tripentylamine, diethanolamine, triethanolamine, triisopropanolamine and the like can be mentioned, and tertiary alkanolamines such as triethanolamine and triisopropanolamine are particularly preferable.
These may be used alone or in combination of two or more.
(D) component is normally used in 0.01-5.0 mass parts with respect to 100 mass parts of (A) component.

In addition, in the chemically amplified resist composition, an organic carboxylic acid or an organic carboxylic acid is added as an optional component for the purpose of preventing sensitivity deterioration due to the blending with the component (D), and improving the pattern shape, retention stability and the like. Phosphorus oxoacid or derivative thereof (E) (hereinafter referred to as component (E)) can be contained. In addition, (D) component and (E) component can also be used together, and any 1 type can also be used.
As the organic carboxylic acid, for example, malonic acid, citric acid, malic acid, succinic acid, benzoic acid, salicylic acid and the like are suitable.
Phosphorus oxoacids or derivatives thereof include phosphoric acid, phosphoric acid di-n-butyl ester, phosphoric acid diphenyl ester and other phosphoric acid or derivatives thereof such as phosphonic acid, phosphonic acid dimethyl ester, phosphonic acid- Like phosphonic acids such as di-n-butyl ester, phenylphosphonic acid, phosphonic acid diphenyl ester, phosphonic acid dibenzyl ester and derivatives thereof, phosphinic acids such as phosphinic acid, phenylphosphinic acid and their esters Among these, phosphonic acid is particularly preferable.
(E) A component is normally used in the ratio of 0.01-5.0 mass parts per 100 mass parts of (A) component.

  If desired, the chemically amplified resist composition may further contain miscible additives such as an additional resin for improving the performance of the coating film of the resist composition, a surfactant for improving the coating property, A dissolution inhibitor, a plasticizer, a stabilizer, a colorant, an antihalation agent and the like can be appropriately contained.

<(S) component>
As the component (S), any component can be used as long as it can dissolve each component to be used to form a uniform solution. More than one species can be appropriately selected and used.
Specific examples include lactones such as γ-butyrolactone, ketones such as acetone, methyl ethyl ketone, cyclohexanone, methyl isopentyl ketone, 2-heptanone, ethylene glycol, ethylene glycol monoacetate, diethylene glycol, diethylene glycol monoacetate, propylene glycol, propylene Polyhydric alcohols such as glycol monoacetate, propylene glycol monomethyl ether acetate (PGMEA), dipropylene glycol, or monomethyl ether, monoethyl ether, monopropyl ether, monobutyl ether or monophenyl ether of dipropylene glycol monoacetate and derivatives thereof And cyclic ethers such as dioxane, methyl lactate, ethyl lactate (EL), Methyl, ethyl acetate, butyl acetate, methyl pyruvate, ethyl pyruvate, may be mentioned methyl methoxypropionate, and esters such as ethyl ethoxypropionate. Among these, PGMEA, EL, and propylene glycol monomethyl ether (PGME) are preferable. These organic solvents may be used independently and may be used as 2 or more types of mixed solvents.
The amount of component (S) used is not particularly limited. Usually, an amount is used in which the chemically amplified resist composition becomes a liquid having a concentration that can be applied onto the support.

[Organic film forming material]
In the above-described film forming step (1), when the support 1 in which an organic film is formed on a substrate is used, the organic film forming material for forming the organic film may be a semiconductor element or a liquid crystal display. In the manufacture of the element, a resist or resin that is generally used may be used.
Note that the organic film forming material does not necessarily require sensitivity to an electron beam or light as in a resist film.
In addition, the organic film forming material is formed so that an organic film pattern can be formed by transferring the composite pattern to the organic film by etching the organic film using the composite pattern formed by the pattern forming method of the present invention. A material that can form an organic film that can be etched, particularly dry-etched is preferable.
Among these, a material capable of forming an organic film that can be etched such as oxygen plasma etching is preferable.
Such an organic film forming material may be a material conventionally used for forming an organic film such as an organic BARC. Examples include the ARC series manufactured by Brewer Science, the AR series manufactured by Rohm and Haas, and the SWK series manufactured by Tokyo Ohka Kogyo.
In particular, as described above, when oxygen plasma etching is used in the etching process, the organic film is easily etched by oxygen plasma etching, and a fluorine gas such as halogen gas, specifically CF ₄ gas or CHF ₃ gas, is used. It is preferable to use a material having a relatively high resistance to gas.
Further, an organic film containing at least one resin component selected from the group consisting of novolak resin, acrylic resin and soluble polyimide may be formed between the organic BARC and the substrate.
These materials are suitable for the present invention because they are easy to perform etching such as oxygen plasma etching and have high resistance to fluorocarbon gases. That is, in general, etching of a substrate or the like is performed using a halogen gas such as a fluorocarbon-based gas. Therefore, by forming an organic film from such a material, oxygen plasma etching is used when forming an organic film pattern. Etching resistance can be improved in a subsequent process using a halogen gas such as a fluorocarbon-based gas for etching the substrate and the like.
These resin components may be used individually by 1 type, and 2 or more types may be mixed and used for them.

Among the above, a novolak resin and an acrylic resin having an alicyclic moiety or an aromatic ring in the side chain are preferably used because they are inexpensive and widely used and have excellent resistance to dry etching using a fluorocarbon-based gas. Used.
As the novolac resin, those generally used in positive resist compositions can be used, and i-line and g-line positive resists containing novolac resin as a main component can also be used.

The novolac resin is a resin obtained by, for example, addition condensation of an aromatic compound having a phenolic hydroxyl group (hereinafter simply referred to as “phenols”) and an aldehyde under an acid catalyst.
Examples of phenols include phenol, o-cresol, m-cresol, p-cresol, o-ethylphenol, m-ethylphenol, p-ethylphenol, o-butylphenol, m-butylphenol, p-butylphenol, 2, 3 -Xylenol, 2,4-xylenol, 2,5-xylenol, 2,6-xylenol, 3,4-xylenol, 3,5-xylenol, 2,3,5-trimethylphenol, 3,4,5-trimethylphenol , P-phenylphenol, resorcinol, hydroquinone, hydroquinone monomethyl ether, pyrogallol, phloroglicinol, hydroxydiphenyl, bisphenol A, gallic acid, gallic acid ester, α-naphthol, β-naphthol and the like.
Examples of aldehydes include formaldehyde, furfural, benzaldehyde, nitrobenzaldehyde, acetaldehyde and the like.
The catalyst for the addition condensation reaction is not particularly limited. For example, hydrochloric acid, nitric acid, sulfuric acid, formic acid, oxalic acid, acetic acid and the like are used as the acid catalyst.
As the novolak resin, a commercially available product can be used.

The lower limit of the mass average molecular weight (Mw) of the novolak resin is preferably 3000 or more, more preferably 5000 or more, more preferably 6000 or more, and further preferably 7000 or more. As an upper limit, 50000 or less is preferable, 30000 or less is more preferable, 10,000 or less is further more preferable, and 9000 or less is the most preferable.
When Mw is 3000 or more, it is difficult to sublime when baked at a high temperature, and the device or the like is hardly contaminated. Further, it is preferable to set Mw to 5000 or more because etching resistance against a fluorocarbon gas or the like is excellent.
Further, when Mw is 50000 or less, good embedding characteristics with respect to a substrate having fine irregularities are excellent, and when it is 10,000 or less, dry etching tends to be easy, which is preferable.

As the novolak resin, in particular, the content of low nuclei having a Mw of 5000 to 50000, preferably 8000 to 30000, and a molecular weight of 500 or less, preferably 200 or less, is gel permeation chromatography ( In the GPC method, a novolak resin of 1% by mass or less, preferably 0.8% by mass or less is preferred. The content of the low nucleus is preferably as small as possible, and is desirably 0% by mass.
In the novolak resin having Mw within the above range, the content of the low nucleus having a molecular weight of 500 or less is 1% by mass or less, so that the embedding property with respect to the substrate having fine irregularities is improved. Although the reason why the embedding property is improved by reducing the content of the low nuclei is not clear, it is presumed that the degree of dispersion becomes small.
Here, the “low molecular weight body having a molecular weight of 500 or less” is detected as a low molecular fraction having a molecular weight of 500 or less when analyzed by GPC using polystyrene as a standard. “Low-nuclear bodies having a molecular weight of 500 or less” include monomers that have not been polymerized and those having a low degree of polymerization, such as those obtained by condensing 2-5 molecules of phenols with aldehydes, depending on the molecular weight. .
The content (mass%) of the low-nuclear body having a molecular weight of 500 or less is graphed with the analysis result by the GPC method taking the fraction number on the horizontal axis and the concentration on the vertical axis, and the molecular weight of 500 or less with respect to the area under the entire curve. It is measured by determining the percentage (%) of the area under the curve of the low molecular fraction.

As the acrylic resin, those generally used in positive resist compositions can be used. For example, a structural unit derived from a polymerizable compound having an ether bond and a polymerizable compound having a carboxy group can be used. Mention may be made of acrylic resins containing derived structural units.
Examples of the polymerizable compound having an ether bond include 2-methoxyethyl (meth) acrylate, methoxytriethylene glycol (meth) acrylate, 3-methoxybutyl (meth) acrylate, ethyl carbitol (meth) acrylate, phenoxy polyethylene glycol (meta And (meth) acrylic acid derivatives having an ether bond and an ester bond such as acrylate, methoxypolypropylene glycol (meth) acrylate, and tetrahydrofurfuryl (meth) acrylate. These compounds can be used alone or in combination of two or more. In the present specification, (meth) acrylate represents one or both of acrylate and methacrylate.
Examples of the polymerizable compound having a carboxy group include monocarboxylic acids such as acrylic acid, methacrylic acid, and crotonic acid; dicarboxylic acids such as maleic acid, fumaric acid, and itaconic acid; 2-methacryloyloxyethyl succinic acid, and 2-methacryloyloxyethyl. Examples include maleic acid, 2-methacryloyloxyethyl phthalic acid, 2-methacryloyloxyethyl hexahydrophthalic acid and other compounds having a carboxy group and an ester bond, and acrylic acid and methacrylic acid are preferred. These compounds can be used alone or in combination of two or more.
A soluble polyimide is a polyimide that can be made liquid by an organic solvent.

The organic film-forming material further contains miscible additives as desired, for example, additional resins for improving the performance of organic films, surfactants for improving coating properties, dissolution inhibitors, plasticizers, Stabilizers, colorants, antihalation agents and the like can be appropriately contained.
The organic film forming material can be manufactured by dissolving the above-described materials such as the resin component in an organic solvent. As an organic solvent, the thing similar to what was illustrated as (S) component of the chemically amplified resist composition mentioned above can be used.

[Production Example 1]
Silicon tetraisocyanate (Si (NCO) ₄ ) was dissolved in p-menthane to a concentration of 50 mM to prepare a metal oxide film forming material.

The resist compositions used in the following Examples 1-2 and Comparative Examples 1-3 are as follows.
Resist composition 1: TArF-6016ME (manufactured by Tokyo Ohka Kogyo Co., Ltd.).
Resist composition 2: TArF-6a128EL (manufactured by Tokyo Ohka Kogyo Co., Ltd.).

[Example 1]
A pattern was formed by the following procedure.
(First step)
The resist composition 1 was uniformly applied by spin coating on an 8-inch silicon substrate on which an organic antireflection film was formed by ARC29 (trade name, manufactured by Brewer Science Co., Ltd.) on the surface, at 115 ° C. for 90 seconds. A resist film having a thickness of 120 nm was formed by performing pre-baking (PAB).
Next, this resist film was selectively exposed through a mask at an exposure amount of 20 mJ / cm ² using an ArF excimer laser exposure machine NSR-S302 (manufactured by Nikon, NA = 0.6). Then, after post-exposure heating (PEB) was performed at 120 ° C. for 90 seconds, development was performed for 30 seconds using an aqueous 2.38 mass% tetramethylammonium hydroxide solution. As a result, a line-and-space resist pattern (hereinafter referred to as pattern (1)) in which line patterns with a line width of 120 nm were arranged at equal intervals (pitch 360 nm) was formed on the resist film.
Next, the metal oxide film-forming material obtained in Production Example 1 is uniformly applied by spin coating (100 rpm for 10 seconds) onto the substrate on which the pattern (1) is formed, and then washed with p-menthane. (500 rpm for 15 seconds), and further, dry drying at 2000 rpm for 10 seconds and 3000 rpm for 10 seconds to protect the surface of the line pattern with the metal oxide film forming material. Subsequently, a 2.38 mass% tetramethylammonium hydroxide aqueous solution was applied to the surface, allowed to stand for 30 seconds, and then washed with pure water. Subsequently, the coating film (silicon oxide film (SiO ₂ )) was formed on the surface of the line pattern by performing high-temperature baking at 200 ° C. for 60 seconds in a baking furnace and drying.

The following evaluation was performed using the substrate after the first step (a substrate on which a line pattern coated with a coating film (covered line pattern) was formed).
(Solvent resistance evaluation)
A mixed solvent of PGMEA and PGME (mass ratio 6: 4) was uniformly applied to the surface of the substrate after the first step, and then dried at 110 ° C. for 60 seconds, and then the shape of the coated line pattern was observed. .
As a result, the covering line pattern maintained the shape before applying the mixed solvent thereon without dissolving. Thereby, it has confirmed that a covering line pattern was excellent in solvent tolerance.

(Exposure / development resistance evaluation)
Wherein with respect to the substrate after the first step, by using an ArF excimer laser exposure machine NSR-S302 (Nikon Corp.), while changing the exposure amount from 5 mJ / cm ² in the range of 100 mJ / cm ² by 5 mJ / cm ² Full open exposure was performed. Subsequently, after post-exposure heating (PEB) was performed at 110 ° C. for 60 seconds, development was performed for 30 seconds using a 2.38 mass% tetramethylammonium hydroxide aqueous solution.
When the shape of the coated line pattern on the substrate was observed, the coated line pattern maintained the shape before exposure without dissolving at any exposure amount. This confirmed that the coated line pattern was excellent in exposure / development resistance.

(Second step)
Next, on the substrate obtained in the first step (the substrate on which the covering line pattern is formed), the resist composition 1 is applied again so as to have a film thickness of 120 nm, as described above, and PAB is applied. And a resist film was formed. Then, the mask of the ArF excimer laser exposure machine used in the first step is shifted so that a line pattern having a line width of 120 nm is formed in the space portion of the covering line pattern, and the resist film is moved to the first step. The film was exposed and developed under the same conditions.
As a result, line patterns having a line width of 120 nm were formed in the gaps between the plurality of covered line patterns.
Moreover, at this time, the shape before the resist composition was applied thereon was maintained without dissolving the covering line pattern.

[Example 2]
In Example 1, a first step was performed in the same manner as in Example 1 except that the resist composition 2 was used in place of the resist composition 1 to form a coated line pattern on the substrate.

About this board | substrate, solvent resistance evaluation was performed like the said Example 1 except having used EL instead of the mixed solvent (mass ratio 6: 4) of PGMEA and PGME.
As a result, the covering line pattern maintained the shape before applying the mixed solvent thereon without dissolving. Thereby, it has confirmed that a covering line pattern was excellent in solvent tolerance.

The substrate was subjected to exposure / development resistance evaluation in the same manner as in Example 1.
As a result, the covering line pattern maintained the shape before exposure without dissolving at any exposure amount. This confirmed that the coated line pattern was excellent in exposure / development resistance.

Moreover, the 2nd process was performed like Example 1 except having used the board | substrate obtained above and using the resist composition 2 instead of the resist composition 1. FIG.
As a result, as in Example 1, line patterns having a line width of 120 nm were formed on the substrate in the gaps between the plurality of covered line patterns. At this time, the covered line patterns were not dissolved. The shape before the resist composition was applied thereon was maintained.

[Comparative Example 1]
In the same manner as in the first step of Example 1, a pattern (1) was formed on a silicon substrate having an antireflection film formed on the surface.
Next, a mixed solvent of PGMEA and PGME (mass ratio 6: 4) was uniformly applied on the substrate on which the pattern (1) was formed, and then dried at 110 ° C. for 60 seconds.
At this time, when the substrate surface was observed, the pattern (1) was dissolved, and the shape before applying the mixed solvent could not be maintained.

[Comparative Example 2]
In the same manner as in the first step of Example 1, a pattern (1) was formed on a silicon substrate having an antireflection film formed on the surface.
Next, the metal oxide film forming material obtained in Production Example 1 was uniformly applied by spin coating (10 seconds at 100 rpm) onto the substrate on which the pattern (1) was formed, and then p-menthane. Washing was performed (500 rpm for 15 seconds), and further, dry drying was performed at 2000 rpm for 10 seconds and 3000 rpm for 10 seconds, and the surface of the line pattern was protected with a metal oxide film forming material. Subsequently, a baking process was performed at 120 ° C. for 60 seconds in a baking furnace, followed by drying to form a coating film (silicon oxide film (SiO ₂ )) on the surface of the line pattern.
About the obtained board | substrate (board | substrate with which the covering line pattern was formed), exposure / development tolerance evaluation was performed similarly to Example 1. FIG.
As a result, in any case where the exposure amount was 5 mJ / cm ² to 100 mJ / cm ² , the coated line pattern was dissolved and the shape before exposure could not be maintained.

[Comparative Example 3]
In the same manner as in the first step of Example 1, a pattern (1) was formed on a silicon substrate having an antireflection film formed on the surface.
Next, the metal oxide film forming material obtained in Production Example 1 was uniformly applied by spin coating (10 seconds at 100 rpm) onto the substrate on which the pattern (1) was formed, and then p-menthane. Washing was performed (500 rpm for 15 seconds), and further, dry drying was performed at 2000 rpm for 10 seconds and 3000 rpm for 10 seconds, and the surface of the line pattern was protected with a metal oxide film forming material. Subsequently, a baking process was performed at 200 ° C. for 60 seconds in a baking furnace, followed by drying to form a coating film (silicon oxide film (SiO ₂ )) on the surface of the line pattern.
About the obtained board | substrate (board | substrate with which the covering line pattern was formed), exposure / development tolerance evaluation was performed similarly to Example 1. FIG.
As a result, when the exposure amount was 20 mJ / cm ² or more, the collapse of the coated line pattern was observed. At 100 mJ / cm ² , the coated line pattern was completely dissolved, and the shape before exposure could not be maintained.

It is a schematic process drawing explaining the preferred embodiment of the pattern formation method of this invention. It is a schematic process drawing explaining an example of the conventional double patterning method.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Support body, 2 ... 1st resist film, 3 ... 1st resist pattern, 4 ... Cover film, 5 ... Cover pattern, 6 ... 2nd resist film, 7 ... 2nd resist pattern, 101 ... Substrate, 102 ... lower layer film, 103 ... hard mask, 104 ... resist pattern, 105 ... mask, 106 ... resist pattern.

Claims (3)

A pattern forming method for forming a pattern using a chemically amplified resist composition,
A step of applying a first chemically amplified resist composition on a support to form a first resist film, and selectively exposing the first resist film through a first mask pattern. A step of forming a first resist pattern by development, a step of forming a coating film made of a metal oxide film on the surface of the first resist pattern, and a step of forming the coating pattern A step of performing an alkali treatment on the surface of the support, a step of applying a second chemically amplified resist composition on the support on which the coating pattern is formed, and forming a second resist film; the second resist film, the second selectively exposed through a mask pattern and developed to look including a step of forming a pattern, the covering layer, the metal compounds capable of forming a hydroxyl group by hydrolysis ( W) is an organic solvent (S ' The pattern forming method is characterized in that it is formed using a metal oxide film-forming material dissolved in (1) .   The pattern forming method according to claim 1, further comprising a step of baking the coating pattern at a temperature of 200 ° C. or higher before applying the second chemically amplified resist composition after the alkali treatment. The metal compound (W) is, the pattern forming method according to claim 1 or 2, wherein the silicon compound having two or more isocyanate groups.

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