WO2005073811A1 - Positive resist composition and method of forming resist pattern - Google Patents

Abstract

A positive resist composition for immersion exposure operation, wherein (1) when the sensitivity at formation of a 150 nm line-and-space 1:1 pattern by subjecting the positive resist composition to ordinary exposure using KrF excimer laser is referred to as X1 while the sensitivity at formation of similar pattern by a simulated immersion lithography consisting of the same operation as the above operation using the ordinary exposure plus an operation of effecting solvent-resist film contact between exposure and post-exposure heating is referred to as X2, the absolute value of [(X2/X1)-1]×100 is 5 or less, and wherein (2) resin component (A) having hydroxystyrene units is blended.

Description

 Specification

 Positive resist composition and resist pattern forming method

 Technical field

 The present invention relates to a positive resist composition and a method for forming a resist pattern.

 This application is based on Japanese Patent Application No. 2004-24579 filed with the Japan Patent Office on January 30, 2004 and Japanese Patent Application No. 2004-119496 filed with the Japan Patent Office on April 14, 2004. Claim priority, the contents of which are incorporated herein.

 Background art

 [0002] In the production of microstructures in various electronic devices such as semiconductor devices and liquid crystal devices, a lithography method is frequently used. With the miniaturization of device structures, the miniaturization of resist patterns in the lithography process has been increasing. Is required.

 At present, for example, KrF excimer laser and ArF excimer laser are used in mass production of semiconductor devices using a lithography method. In the future, finer pattern formation will be required.

 In order to achieve fine pattern formation, the development of exposure equipment and the corresponding resist is the first. For exposure equipment, ArF excimer laser, F laser, EUV

 2

 (Extreme ultraviolet light), electron beams, X-rays, and other light source wavelengths are generally shortened, and the numerical aperture (NA) of the lens is increased.

 However, shortening the wavelength of the light source requires an expensive new exposure apparatus, and in the case of high NA, there is a trade-off between resolution and depth of focus. However, there is a problem that the depth of focus is reduced.

[0003] Under such circumstances, a method called immersion lithography has been reported (see, for example, Non-Patent Document 1, Non-Patent Document 2, and Non-Patent Document 3). In this method, at the time of exposure, a solvent having a refractive index larger than the refractive index of air is applied to the portion between the lens and the resist layer (resist film) on the wafer, which was conventionally an inert gas such as air or nitrogen, For example, it is filled with a solvent such as pure water or a fluorine-containing inert liquid. By filling with such a solvent, even if a light source with the same exposure wavelength is used, a light source with a shorter wavelength or a high NA lens can be used. It is said that, as in the case of (1), high resolution is achieved and the depth of focus does not decrease.

 By using such immersion lithography, it is possible to form a resist pattern with low cost, high resolution, and excellent depth of focus using a lens mounted on existing equipment. For this reason, it has attracted much attention.

 Non-Patent Document 1: Journal of Vacuum Science & Technology B (USA), 1999, Vol. 17, No. 6, 3306-3309.

 Non-Patent Document 2: Journal of Vacuum Science & Technology B (USA), 2001, Vol. 19, No. 6, 2353—2356.

 Non-Patent Document 3: Proceedings of SPIE (USA) 2002, Vol. 4691, pp. 459-465.

 Disclosure of the invention

 Problems to be solved by the invention

[0004] As described above, one of the advantages of immersion lithography is that in the manufacture of semiconductor elements that require a large capital investment, there is a great effect on the semiconductor industry in terms of cost and lithography characteristics such as resolution. It is expected to give.

 However, since the resist film comes into contact with the solvent at the time of exposure as described above, the resist film is deteriorated, and a component that adversely affects the solvent is leached from the resist, thereby reducing the refractive index of the solvent. However, there are problems such as loss of the original merits of immersion lithography, and a resist pattern as good as the conventional normal exposure process is formed, or there are still many unknown points.

 In fact, when a certain type of conventional positive resist composition for KrF excimer laser was applied to image lithography, the resist pattern was affected by the solvent and the sensitivity was deteriorated and the resulting resist pattern became a T-top shape. There is a problem that the surface is roughened (profile shape is inferior) or the resist pattern swells.

[0005] The present invention has been made in view of such a problem, and a KrF excimer having a wavelength of 248 nm has been developed. A positive type resist composition and a resist pattern forming method applied to a process using a ma laser are used in an immersion lithography step which does not impair the improvement of resolution and depth of focus which is one of the advantages of immersion lithography. Provided is a positive resist composition and a resist pattern forming method which are used in a resist pattern forming method including an image lithography step and which have an excellent resist pattern profile shape which is less susceptible to adverse effects of a solvent. As an issue.

Means for solving the problem

 In order to achieve the above object, the present invention employs the following configurations.

 The first mode (mode) of the positive resist composition of the present invention is a positive resist composition used for a resist pattern forming method including a step of immersion exposure, and comprises the following (1) and (2): A positive resist composition satisfying the conditions.

 (1) Sensitivity when using the positive resist composition to form a resist pattern in which a 150 nm line and space is one-to-one by a lithography process of normal exposure using a KrF excimer laser having a wavelength of 248 nm as a light source. Is XI,

 On the other hand, in a process similar to the lithography process of the normal exposure using the KrF excimer laser having a wavelength of 248 nm as a light source, the solvent of the immersion exposure is brought into contact with the resist film between the selective exposure and the post-exposure baking (PEB). When the sensitivity at the time of forming a resist pattern with a 150 nm line and space of 1 to 1 by a simulated immersion lithography process using a process is defined as X2,

 [(X2 / XD-1) The absolute value of X100 is 5 or less.

 The solvent is at least one kind selected from water, a fluorine-containing inert solvent and the like, preferably at least one kind selected from water and a fluorine-containing inert solvent, and particularly preferably water.

 (2) The positive resist composition contains a resin component (A) and a compound capable of generating an acid upon exposure (acid generator) (B), wherein the component (A) is represented by the following general formula (I). Having a structural unit (al).

[Chemical 1] (OH) _m … (I)

(In the formula, R represents a hydrogen atom or a methyl group, and m represents an integer of 1 to 3.)

 A second mode (mode) is a positive resist composition used for a resist pattern forming method including a step of immersion exposure,

 A resin component (A) and a compound that generates an acid upon exposure (acid generator) (B);

Component (A) is a hydroxystyrene structural unit (al) represented by the above general formula (I),

 and

 Having a structural unit (a2) having an acid dissociable, dissolution inhibiting group,

This structural unit ( _a2 ) is a positive resist composition containing two or more structural units having acid dissociable, dissolution inhibiting groups having different structures.

 [0007] Further, a method for forming a resist pattern according to the present invention is a method for forming a resist pattern using the resist composition according to the present invention, the method including a step of immersion exposure. .

[0008] In the present specification and the claims, "normal exposure" refers to an inert gas such as air or nitrogen that has been conventionally used between a lens of an exposure apparatus and a resist film on a wafer. Exposure is performed in the state described above.

 “(Meth) acrylic acid” refers to one or both of methacrylic acid and acrylic acid. “(Meta) atelylate” is a generic term for metatarylate and atalylate. “Structural unit” refers to a monomer unit constituting a polymer.

The “lithography step” generally includes a step of sequentially applying resist application, pre-beta, selective exposure, heating after exposure, and alkali development, and optionally includes a post-beta step after the alkali development. The invention's effect In the present invention, a positive resist composition and a resist pattern forming method applied to a process using a KrF excimer laser having a wavelength of 248 nm are described. It is possible to obtain an excellent effect that the sensitivity is not easily deteriorated due to the adverse effect of the solvent used in the immersion lithography process, and the resist pattern profile is excellent.

 BEST MODE FOR CARRYING OUT THE INVENTION

[0010] In making the present invention, the present inventors analyzed a method for evaluating the suitability of a resist film used for a resist pattern forming method including an immersion exposure step as follows, and based on the analysis results, Then, a positive resist composition and a method of forming a resist pattern using the composition were evaluated.

 That is, to evaluate the resist pattern forming performance by immersion exposure,

 (i) performance of optical system by immersion exposure method,

 (ii) the influence of the resist film (resist layer) on the immersion solvent,

 (iii) deterioration of the resist film due to the immersion solvent,

 If these three points can be confirmed, it is determined that it is necessary and sufficient.

[0011] Regarding the performance of the optical system (i), for example, assuming a case in which a photosensitive plate having a water-resistant surface is submerged in water and its surface is irradiated with pattern light, If there is no light propagation loss such as reflection at the interface between water and the surface of the photosensitive plate, there is no doubt in principle that no problem will occur thereafter.

 The light propagation loss in this case can be easily solved by optimizing the incident angle of the exposure light. Therefore, whether the object to be exposed is a resist film, a photographic plate, or an imaging screen, if they are inert to the immersion solvent, If it is not affected and does not affect the immersion solvent, it can be considered that there is no change in the performance of the optical system.

 Therefore, this point falls short of a new confirmation experiment.

[0012] Specifically, the effect of the resist film on the immersion solvent in (ii) is that the components of the resist film dissolve into the liquid and change the refractive index of the immersion solvent.

If the refractive index of the immersion solvent changes, the optical resolution of pattern exposure will change That is clear from the theory that goes without experimenting. In this regard, simply confirming that when the resist film is simply immersed in the immersion solvent, certain components are dissolved and the composition of the immersion solvent changes, or that the refractive index changes. It's enough, even if you actually irradiate the pattern light and develop it to check the resolution.

 Conversely, when the resist film in the immersion solvent is irradiated with pattern light and developed to confirm the resolution, the quality of the resolution can be confirmed, but the resolution due to deterioration of the immersion solvent can be confirmed. The effect on the resolution, the effect of the resolution of the resist film, or both.

, Can not be distinguished.

 [0013] Regarding the point that the resolution deteriorates due to the deterioration of the resist film due to the immersion solvent of (m),

`` Between selective exposure and post-exposure baking (PEB), the immersion solvent is applied to the resist film, for example, as a shower, and then the resist film is contacted, then developed and the resolution of the resulting resist pattern is improved. Is sufficient. In addition, in this evaluation method, the immersion solvent is directly sprinkled on the resist film, and the immersion conditions become more severe. In the case of a test in which exposure is performed in a completely immersed state, the resolution is determined by the influence of the deterioration of the immersion solvent, the force of the resist composition caused by the deterioration of the immersion solvent, or both. It is not clear whether the sex has changed.

 [0014] That is, the phenomena (ii) and (m) are two-sided phenomena, and can be grasped by confirming the degree of deterioration such as deterioration of the pattern shape or sensitivity deterioration due to the immersion solvent for the resist film. . Therefore, if only the point (iii) is verified, the verification related to the point (ii) is also included.

 Based on these analyses, the immersion exposure suitability of a resist film formed from a new resist composition suitable for the immersion exposure process was described as `` using an immersion solvent between selective exposure and post-exposure bake (PEB). For example, a process of contacting the resist film with a resist film as in a shower is performed, and then developed, and the resolution of the obtained resist pattern is detected. "

 [Positive resist composition]

 ♦ First embodiment (embodiment)

The resist composition of the present embodiment (embodiment) comprises a resist including a step of immersion exposure. A positive resist composition used in a pattern forming method, characterized by satisfying the following conditions (1) and (2).

 (1) Sensitivity when using the positive resist composition to form a resist pattern in which a 150 nm line and space is one-to-one by a lithography process of normal exposure using a KrF excimer laser having a wavelength of 248 nm as a light source. Is XI,

 On the other hand, in a process similar to the lithography process of the normal exposure using the KrF excimer laser having a wavelength of 248 nm as a light source, the solvent of the immersion exposure is brought into contact with the resist film between the selective exposure and the post-exposure baking (PEB). When the sensitivity at the time of forming a resist pattern with a 150 nm line and space of 1 to 1 by a simulated immersion lithography process using a process is defined as X2,

 [(X2 / XD-1) The absolute value of X100 is 5 or less.

 The solvent is at least one kind selected from water, a fluorine-containing inert solvent and the like, preferably at least one kind selected from water and a fluorine-containing inert solvent, and particularly preferably water.

 (2) The positive resist composition contains a resin component (A) and a compound that generates an acid upon exposure (acid generator) (B), wherein the component (A) is represented by the general formula (I). Having a structural unit (al).

· Condition (1):

 The absolute value of [(X2 / X1) -1] X100 is 5 or less, preferably 3 or less, more preferably 1 or less, and the closer to 0, the more preferable.

 By satisfying this range, it is extremely suitable as a resist composition for the immersion exposure process for the process of exposing with the KrF excimer laser, and is not easily affected by the solvent used in one step of the immersion lithography. It has the effect of being excellent in resist pattern profile shape with less sensitivity deterioration.

 If the absolute value exceeds 5, it is unsuitable as a resist composition for the immersion exposure process for the KrF excimer laser exposure process, and the resist pattern may have a T-top shape or the resist pattern may collapse. Such troubles occur.

The absolute value is obtained by changing the composition of a resist composition such as a resin component and an acid generator. Can be changed. Preferably, a positive resist composition of an embodiment (embodiment) after a second embodiment (embodiment) described later is employed.

 It should be noted that, as shown in the condition (2), even if a resin component having a structural unit (al) having a hydrophilic group such as a hydroxyl group is contained, a resist composition in which the absolute value is in a small range is constituted. Alternatively, the absolute value may be large even when the same structural unit (al) is included. Therefore, it is difficult to specify the invention according to the present embodiment (embodiment) by the specific composition of the resist composition other than the structural unit (al). Therefore, in the invention according to the present embodiment (embodiment), the invention is specified by the absolute value as the condition (1). The resist composition of the invention according to the present embodiment (embodiment) can be easily specified by a simple test whether or not the absolute value satisfies the range of the invention according to the present embodiment (embodiment).

[0017] The lithography process of normal exposure using a KrF excimer laser having a wavelength of 248 nm as a light source refers to a lens of an exposure apparatus and a wafer which are conventionally used with a KrF excimer laser having a wavelength of 248 nm as a light source. Exposure between the resist films in the state of an inert gas such as air or nitrogen is performed on a substrate such as a silicon wafer by the normal exposure, i.e., resist coating, pre-beta, selective exposure, and exposure. It means a step of sequentially performing post-heating and alkali development.

 In some cases, a post-beta step after the alkali development may be included, or an organic or inorganic antireflection film may be provided between the substrate and the coating layer of the resist composition.

 When a resist pattern (hereinafter referred to as “150 nmL & S”) having a 150 nm line-and-space ratio of 1 to 1 is formed by such a normal exposure lithography process, the sensitivity X1 is 150 nmL & S. Exposure is a technical term frequently used by those skilled in the art and is obvious.

[0018] As a precautionary measure, this sensitivity will be described temporarily.

 First, the exposure amount is plotted on the horizontal axis, the resist line width formed by the exposure amount is plotted on the vertical axis, and a logarithmic approximation curve is obtained from the obtained plot by the least square method.

The equation is given by Y = aLoge (Xl) + b, where XI is the exposure and Y is the resist line A and b are constants. Further, if this expression is expanded to an expression representing XI, Xl = Exp [(Yb) / a]. By introducing Y = 150 (nm) into this equation, the calculated ideal sensitivity XI is calculated.

[0019] The conditions at that time, ie, the number of rotations of the resist coating, the pre-beta temperature, the exposure condition, the heating condition after exposure, and the alkali development condition are also those under the conditions conventionally used up to 150 nmL & S. It is obvious. Specifically, the rotation speed is about 1000-4000 rpm, more specifically about 2000 rpm, and the pre-beta (PAB) temperature is in the range of 70 140 ^o G, which is If the absolute value of [(X2ZX1) _1] X 100 is 5 or less at any point within these ranges, the range of the present invention is within the scope of the present invention. is there.

 Exposure conditions may be exposure through a mask using a KrF excimer laser exposure apparatus with a wavelength of 248 nm manufactured by Nikon Corporation or Canon Inc. (NA = 0.68). An ordinary binary mask is used as a mask in the selective exposure. As the mask, a phase shift mask may be used.

Post exposure baking (PEB) temperature is in the range of 90- 140 ° C, alkali development conditions, 2. The 38 weight ⁰ / ^oTMAH (tetramethylammonium Niu beam hydroxide) developer at 23 ° C, 15 — Develop for 90 seconds, more specifically 60 seconds, then rinse with water.

 The temperature conditions of PAB and PEB are optimized for each resist composition. It is obvious to those skilled in the art how to determine the optimized conditions.

 Preferred optimized [PAB temperature (° C), PEB temperature (° C)] combinations are [125, 110], [100, 110], [140, 140], and more preferably [125, 110].

[0020] The simulated immersion lithography process is a process similar to the above-described lithography process of normal exposure using a 248 nm KrF excimer laser as a light source, which is performed between selective exposure and post-exposure baking (PEB). Means a step of adding a solvent for immersion exposure to the resist film.

 That is, the conditions of the experiment for obtaining X2 are the same as those for obtaining XI, except for performing the step of bringing the solvent into contact with the resist film.

[0021] Specifically, a solvent for resist coating, pre-beta, selective exposure, and immersion exposure is applied to a resist film. And a step of sequentially performing post-exposure heating and alkali development. In some cases, a post-beta step after the alkali development may be included.

 Contacting means that the solvent on the surface of the resist film and the solvent sufficiently contact each other.For example, the resist film after selective exposure provided on the substrate may be immersed in the solvent for immersion exposure or sprayed like a shower. Regardless, the same result is obtained in each case. The contact time is for example 2-5 minutes.

 Then, the sensitivity X2 when a resist pattern of 150 nmL & S is formed by such a simulated immersion lithography process is the amount of exposure light at which 150 nmL & S is formed in the same manner as in XI, and a technique commonly used by those skilled in the art. Is a term.

 The conditions at that time (the number of rotations of the resist coating, the pre-beta temperature, the exposure conditions, the post-exposure heating conditions, the conditions such as alkali development, etc.) are also the same as those in XI.

The solvent used in the immersion exposure step is water, a fluorine-containing inert liquid described below, or the like, and is preferably water.

 [0023] [(X2 / X1) -1] The absolute value of X100 is self-evident if X2 and XI are determined as described above.

Preferred specific conditions of the normal exposure step for obtaining XI and the simulated immersion lithography step for obtaining X2 are shown below.

 (i) Formation of resist pattern using lithographic process by normal exposure (Measurement of XI) Organic anti-reflective coating composition: Product name DUV42P (manufactured by Bruce Science) was coated with a spinner to a diameter of 6 inches or 8 mm. An organic anti-reflective film with a thickness of 65 nm is formed by applying the film on a silicon wafer of inches or the like, baking it on a hot plate at 185 ° C for 60 seconds, and drying.

 Then, a positive resist composition is applied on the anti-reflection film using a spinner, pre-betaed (PAB) on a hot plate, and dried to form a 350 nm-thick resist film on the anti-reflection film. To form

Next, a KrF excimer laser (248 nm) is selectively irradiated as a reticle using a KrF exposure apparatus S203B (Nikon NA numerical aperture = 0.68, σ = 2Z3 annular illumination) through a binary mask. Next, PEB treatment is performed, and further development is performed at 23 ° C with an alkaline developer for 60 seconds. The alkali current image solution 2.38 wt _^0/0 using a tetramethylammonium Niu arm hydroxide aqueous solution. Thus, a resist pattern in which the 150 nm line and space is 1: 1 is formed, and the sensitivity (Eop): X1 at that time is obtained.

 The PAB and PEB conditions used are optimized for each resist composition. It is obvious to those skilled in the art how to determine the optimized conditions.

 Preferred optimized [PAB temperature (° C), PEB temperature (° C)] combinations are [125, 110], [100, 110], [140, 140], and more preferably [125, 110].

(Ii) Formation of Resist Pattern Using Simulated Immersion Lithography Step (Measurement of X2) The sensitivity (Eop): X2 was changed by performing the same operation as in (i) above except that the simulated immersion exposure treatment was performed. Ask.

 That is, as a simulated immersion exposure process, pure water is continuously dropped at 23 ° C. for 2 minutes while rotating a silicon wafer provided with a resist film between the selective exposure and the PEB process.

 [0026] · Regarding condition (2):

 The positive resist composition of the present embodiment (embodiment) is not particularly limited, and is a chemically amplified type resist composition containing a resin component capable of becoming alkali-soluble by the action of an acid and an acid generator component generating an acid upon exposure. Are preferred.

 · Resin component (A)

 Constituent unit (al)

 The structural unit (al) is represented by the general formula (I).

 As such a positive resist composition for a KrF excimer laser, one containing a resin component having a structural unit (al) having a hydroxyl group is used. In the case where the resin component having a unit having a hydrophilic group is contained, the influence of a solvent such as water is particularly concerned. However, by applying this embodiment (embodiment), it is possible to prevent sensitivity deterioration and obtain a good pattern shape.

In the above general formula (I), R is a hydrogen atom or a methyl group, and is preferably a hydrogen atom. The position of the hydroxyl group may be any of the o-position, m-position, and p-position. P-position is preferred because it is affordable and affordable.

[0028] The amount of the structural unit (al) is the component (A) in 50- 85 mole _^0/0, preferably 60- 80 Monore _^0/0. When the content is not less than the lower limit, good resolution is obtained from the viewpoint of solubility in a developing solution and the like, and when the content is not more than the upper limit, the condition (1) can be easily satisfied. In addition, it is possible to suppress the film thickness of the pattern and the like.

 [0029] The component (A) preferably has a structural unit (a2) having an acid dissociable, dissolution inhibiting group.

 By the action of an acid generated from the component (B) upon exposure, the acid dissociable, dissolution inhibiting group is dissociated in the structural unit (a2), whereby the resin component (A) becomes alkali-soluble. As a result, a resist pattern can be formed.

 [0030] Structural unit (a2)

 As the structural unit (a2), various types have been proposed, and these can be arbitrarily selected and used.

 [0031] For example, as described below, the structural unit (a2-1) in which the acid dissociable, dissolution inhibiting group is an alkoxyalkyl group, and the acid dissociable, dissolution inhibiting group is a tertiary alkoxycarbonyl group and / or a tertiary alkyl group. The structural unit (a2-2) [including the structural unit having an aliphatic cyclic group (a2-3)], and the acid dissociable, dissolution inhibiting group is a crosslinking group represented by the following general formula (II). Structural units and the like can be used arbitrarily.

 The main chain of the structural unit (a2) may be a (meth) acrylic acid skeleton or a hydroxystyrene skeleton represented by the above general formula (I) (hereinafter, these “(meth) ataryl” An “acid skeleton” or “hydroxystyrene skeleton” may be referred to as a “backbone”.) In the case of the (meth) acrylic acid skeleton, a structure in which the ethylenic double bond is cleaved and an acid dissociable, dissolution inhibiting group is bonded instead of the hydrogen of the carboxyl group [1-C (O) -O-R] '; R' is a structural unit having an acid dissociable, dissolution inhibiting group]. In the case of a hydroxystyrene skeleton, a structural unit in which hydrogen of a hydroxyl group is substituted with an acid dissociable, dissolution inhibiting group is used.

 [0032] The skeleton of the main chain is appropriately selected depending on the type of the acid dissociable, dissolution inhibiting group and the like. For example, in the case of a (meth) acrylic acid skeleton, a tertiary alkyl group or the following crosslinking group is mainly used.

In the case of the hydroxystyrene skeleton represented by the general formula (I), an alkoxyalkyl group, Tertiary alkoxycarbonyl groups, tertiary alkyl groups, the following crosslinking groups, and the like are used.

 The structural unit (a2) is a structural unit having an acid dissociable, dissolution inhibiting group having a different structure.

 It is preferable to contain two or more types. Here, the “acid dissociable, dissolution inhibiting group having a different structure” means that the chemical formula of the “acid dissociable, dissolution inhibiting group” is different.

 That is, for example, when the two types of the first structural unit and the second structural unit are mixed and used in the structural unit (a2), the acid dissociable, dissolution inhibiting group of the first structural unit and the second structural unit This means that the chemical formula of the acid dissociable, dissolution inhibiting group having the following structure is different.

 Thereby, the effect is improved.

 As described above, three or more structural units having an acid dissociable, dissolution inhibiting group having different structures can be mixed, and it is desirable that two structural units be used from the viewpoints of effects and simplicity of processing. When a plurality of types of structural units having different structures of the acid dissociable, dissolution inhibiting group are combined in the structural unit (a2), it is preferable that each of the structural units contains 1 mol% or more of the component (A). More preferably, it is contained at least 3 mol%.

[0034] The proportion of the structural unit (a2) component (A) in 5 to 50 mole _^0/0, Ru preferably 10 45 mol _^0/0 der. When the content is not less than the lower limit, the content is preferably not more than the upper limit from the viewpoint of improvement in resolution, solubility in a developing solution, and the like, whereby the balance with the structural unit (al) and the like can be achieved.

The component (A) may include a structural unit other than the structural unit (al) and the structural unit (a2). Examples of the other structural unit include a structural unit (a3) represented by the following general formula (III).

 [0036] Structural unit (a3)

The structural unit (a3) is represented by the following general formula (III). [0037] [Formula 2]

(In the formula, R represents a hydrogen atom or a methyl group, R ¹ represents an alkyl group having 15 to 15 carbon atoms, and 1 represents an integer of 0 or 113.)

[0038] In the structural unit (a3), R is a hydrogen atom or a methyl group, and is preferably a hydrogen atom.

R ¹ is a linear or branched alkyl group having 115 carbon atoms, such as methyl, ethyl, propyl, isopropyl, n-butyl, isobutyl, tert-butyl, pentyl, Examples include an isopentyl group and a neopentyl group. Industrially, a methyl group or an ethyl group is preferred.

 The above 1 is 0 or an integer of 1 to 3. Among these, 1 is preferably 0 or 1, and particularly preferably 0 industrially.

In addition, when 1 is 1 to 3, R ¹ may be substituted at any of the o-, m-, and p-positions. Further, when 1 is 2 or 3, any substitution may be performed. Can combine positions

[0039] The proportion of the structural unit (a3) component (A) in 1 one 30 mole _^0/0, preferably from 2 to 15 mol _^0/0. By setting the lower limit or more, the resist pattern shape is improved, and by setting the lower limit or less, which is preferable from the viewpoint of solubility in a developing solution, the balance with the structural units (al), (a2), etc. Can be taken.

 [0040] The component (A) can be used alone or as a mixture of two or more.

The mass average molecular weight of the component (A) [Mw: mass average molecular weight in terms of positive styrene by GPC (gel permeation chromatography)] is 5000 to 30000, and preferably 6000 to 15 000. The amount of the component (A) in the resist composition is 5 to 20% by mass, preferably 8 to 15% by mass.

··· Acid generator (B)

 As the component (B), a known acid generator used in a conventional chemically amplified photoresist composition can be arbitrarily used.

 That is, as the acid generator, there have hitherto been used a dominate-based acid generator such as a rhododium salt or a sulfonium salt; an oxime sulfonate-based acid generator; a bisalkyl or bisarylsulfonyldiazomethane; Diazomethane-based acid generators such as (bissulfonyl) diazomethanes and diazomethane-ditrobenzyl sulfonates; and many other types such as iminosulfonate-based acid generators and disulfone-based acid generators are known. Known acid generators can be used without particular limitation.

 [0042] Among the diazomethane-based acid generators, specific examples of bisalkyl or bisarylsulfonyldiazomethane-based acid generators include bis (isopropylsulfonyl) diazomethane, bis (p-toluenesulfoninole) diazomethane, Bis (1,1-dimethylethylsulfoninole) diazomethane, bis (cyclohexylsulfonyl) diazomethane, bis (cyclopentylsulfoninole) diazomethane, bis (2,4-dimethylphenylsulfonyl) diazomethane and the like can be mentioned.

Among the diazomethane-based acid generators, poly (bissulfonyl) diazomethane-based acid generators include, for example, 1,3-bis (phenylsulfonyldiazomethylsulfonyl) propane having the following structure 1,4-bis (phenylsulfonyldiazomethylsulfonyl) butane (disulfide B, decomposition point 147 ° C), 1,6-bis (phenylsulfonate) Rudazomethylsulfonyl) hexane (disulfide compound C, melting point 132 ° C, decomposition point 145 ° C), 1,10_bis (phenylsulfonyldiazomethylsulfonyl) decane (compound D, decomposition point 147 .C), 1, 2_ bis (cyclohexyl sulfonyl di § zone methylsulfonyl cyclohexane) Etan (I匕合product E, decomposition point 149.C), 1, ³ _ bis (cyclohexyl sulfonyl di § zo methyl cyclohexane Sulfonyl) pupan (Compound F, decomposition point 153.C), 1 , 6_bis (cyclohexylsulfonyldiazomethylsulfonyl) hexane (disulfide G, melting point 109.C, decomposition point 122.C), 1,10_bis (cyclohexylsulfonyldia) Zomethylsulfonyl) decane (distilled compound H, decomposition point 116 ° C). [0044]

[0045] Specific examples of the oxime sulfonate-based acid generator include α_ (methylsulfonyloximino) -phenylacetonitrile, and a- (methylsulfonyloximino) _p-methoxyphene. Diacetonitrile, a- (trifluoromethylsulfonyloximino) -phenylacetonitrile, α- (trifluoromethylsulfonyloxymino) -p-methoxyphenylacetonitrile, α- (ethylsulfonyloxy) Simino)-ρ-methoxyphenylacetonitrile, α- (propylsulfonyloximino)-ρ_methylphenylacetonitrile, hi- (methylsulfonyloxyminino)-ρ_bromophenylacetonitrile and the like. Among these

,-(Methylsulfonyloxyimino) _p-Methoxyphenylacetonitrile is preferred.

[0046] As described above, examples of the onium salt-based acid generator include an odonium salt-based acid generator containing iodine in the cation and a sulfonium salt-based acid generator containing sulfur in the cation.

[0047] Specific examples of the acid salt-based acid generator include: trifluoromethanesulfonate or nonafluorobutanesulfonate of difluoronium, trifluoromethanesulfonate or nonafluorobutane of bis (4_tert_butylpheninole) odonium. Sulfonate and the like.

 [0048] Specific examples of the sulfonium salt-based acid generator include trifluoromethanesulfonate of triphenylsulfonium, heptafluoropropanesulfonate or nonafluorobutanesulfonate, and tri (4-methylphenyl) sulfonate. Trifluoromethanesulfonate, its heptafluoropropanesulfonate or its nonafluorobutanesulfonate, its trifluoromethanesulfonate of dimethyl (4-hydroxynaphthinole) sulfonium, its heptaful O-fluoropropanesulfonate or its nonafluorobutanesulfonate, triphenylonemethanesulfonate of monophenyldimethylsulfonium, its heptafluoropropanesulfonate or its nonafluorobutanesulfonate, dipheninolemono Truffle Ruo Lome chest Norre phosphonate chill Sno Reho Niu-time, the hepta unloading Leo Krumlov. Mouth pan sulfonate or its nonafluorobutane sulfonate.

 [0049] The component (B) is not particularly limited and preferably selected depending on the type of the acid dissociable, dissolution inhibiting group of the component (A), but is not particularly limited. The use of at least one selected from diazomethane-based acid generators is preferred in view of the effect of the present embodiment (embodiment), which is less affected by the solvent.

When one or more selected from sulfonium salt-based acid generators and diazomethane-based acid generators are used, they should be present in component (B) in an amount of at least 50% by mass, preferably at least 80% by mass. Is preferred.

 In this case, the diazomethane-based acid generator is preferably a bisalkyl or bisarylsulfonyldiazomethane-based acid generator.

 [0050] The component (B) can be used alone or in combination of two or more.

 The amount of the component (B) used is 0.5-30 parts by mass, preferably 110 parts by mass, per 100 parts by mass of the component (A). When the amount is 0.5 parts by mass or more, pattern formation is sufficiently performed, and when the amount is 30 parts by mass or less, a uniform solution is obtained and storage stability is improved.

 [0051] The positive resist composition of the present embodiment (embodiment) further contains a nitrogen-containing organic compound (D) as an optional component in order to improve the resist pattern shape, the stability with time of storage, and the like. (Hereinafter, referred to as component (D)).

 [0052] · '(D) Nitrogen-containing organic compound

 As the component (D), since a wide variety of components have already been proposed, any known component may be used arbitrarily. Amines, particularly secondary aliphatic amines ゃ tertiary aliphatic amines, are preferred. The aliphatic amine refers to an alkyl or alkyl alcohol amine having 15 or less carbon atoms. Examples of the secondary or tertiary amine include trimethylamine, getylamine, triethynoleamine, di-n-propylamine, and the like. Powers include tri-n-propylamine, tripentinoleamine, tridodecinoleamine, trioctylamine, diethanolamine, triethanolamine, triisopropanol, etc. Class alkanolamines are preferred.

 Also, trisporial coxylalkylamines such as tris- (2-methoxymethoxyethyl) amine, tris-2- (2-methoxy (ethoxy)) ethynoleamine and tris- (2- (2-methoxyethoxy) methoxyethyl) amine Min. Among them, tris_2_ (2-methoxy (ethoxy)) ethylamine is preferred.

 Among these nitrogen-containing organic compounds, tris_2_ (2-methoxy (ethoxy)) ethylamine is preferred because of its low solubility in the solvent used in the imaginion lithography step.

 These can be used alone or in combination of two or more.

Component (D) is usually used in the range of 0.01 to 5.0 parts by mass with respect to 100 parts by mass of component (A). You can.

 [0053] Further, for the purpose of preventing the sensitivity deterioration due to the blending of the component (D) and improving the resist pattern shape, the storage stability, and the like, an organic carboxylic acid or an oxo acid of phosphorus or a phosphoric acid thereof as a further optional component. A derivative (E) (hereinafter, referred to as a component (E)) can be contained. In addition, the component (D) and the component (E) can be used in combination, and four kinds of force can be used eventually.

 [0054] · '(E) component

 As the component (E), for example, malonic acid, citric acid, malic acid, succinic acid, benzoic acid, salicylic acid and the like are suitable.

 Phosphorus oxo acids or derivatives thereof include phosphoric acid such as phosphoric acid, di-n_butyl phosphate and diphenyl phosphate, and derivatives such as esters thereof, phosphonic acid, dimethyl phosphonate, and phosphonic acid. —Phosphonic acids such as di-n_butyl ester, phenylphosphonic acid, diphenylphosphonic acid ester, dibenzylphosphonic acid ester and derivatives thereof, phosphinic acids such as phosphinic acid, phenylphosphinic acid and the like; Derivatives such as esters are mentioned, and among these, phosphonic acid is particularly preferred.

 The component (E) is used in an amount of 0.01 to 5.0 parts by mass per 100 parts by mass of the component (A).

[0055] · · Other optional ingredients

 The positive resist composition of the present embodiment (embodiment) may further contain, if desired, additives that are miscible, for example, an additional resin for improving the performance of the resist film, a surfactant for improving coatability, A dissolution inhibitor, a plasticizer, a stabilizer, a coloring agent, an antihalation agent and the like can be appropriately added and contained.

[0056] The positive resist composition of the present embodiment (embodiment) can be produced by dissolving each material in an organic solvent.

 For example, the components may be mixed and stirred by a usual method, and if necessary, may be dispersed and mixed using a disperser such as a dissolver, a homogenizer, or a three-roll mill. After mixing, the mixture may be further filtered using a mesh or a membrane filter.

[0057] · · Organic solvent Any organic solvent may be used as long as it can dissolve each component used to form a uniform solution.

One or more kinds can be appropriately selected and used.

 For example, ketones such as γ_butyrolataton, acetone, methyl ethyl ketone, cyclohexanone, methyl isoamyl ketone, 2_heptanone, ethylene glycol, ethylene glycol monomonoacetate, diethylene glycolone diethylene glycolone monoacetate, Polyhydric alcohols such as propylene glycolone, propylene glycol monoacetate, dipropylene glycol monoacetate, or dipropylene glycol monoacetate, such as monomethyl ether, monoethyl ether, monopropyl ether, monobutyl ether or monophenyl ether, and derivatives thereof And cyclic ethers such as dioxane, methyl lactate, ethyl lactate (EL), methyl acetate, ethyl acetate, butyl acetate, methyl pyruvate, and pyruvate. Le, methyl methoxypropionate, and esters such as ethoxypropionate Echiru can be exemplified.

 These organic solvents may be used alone or as a mixed solvent of two or more.

[0058] A mixed solvent of propylene glycol monomethyl ether acetate (PGMEA) and a polar solvent is preferable. The mixing ratio may be appropriately determined in consideration of the compatibility between PGMEA and the polar solvent, but is preferably 1: 9 to 9: 1, and more preferably 2: 8 to 8: 2. . Alternatively, it is preferably in the range of 1: 9 to 8: 2, more preferably in the range of 2: 8 to 5: 5. More specifically, when EL is blended as a polar solvent, the mass ratio of PGMEA: EL is preferably 1: 9 to 9: 1, more preferably 2: 8 to 8: 2. Alternatively, it is preferably 2: 8-5: 5, more preferably 3: 7-4: 6.

 In addition, as the organic solvent, a mixed solvent of at least one selected from PGMEA and EL with γ_petit mouth opening is also preferable. In this case, the mixing ratio of the former and the latter is preferably 70: 30-95: 5.

[0059] The amount of the organic solvent to be used is not particularly limited, but is appropriately set at a concentration applicable to a substrate or the like according to the thickness of the applied film. In general, the resist composition is selected so that the solid content of the resist composition is in the range of 2 to 20% by mass, preferably 5 to 15% by mass.

[0060] ♦ Second embodiment (embodiment): According to a second embodiment (embodiment), in the positive resist composition of the first embodiment (embodiment), the component (A) has a structural unit (a2) having an acid dissociable, dissolution inhibiting group. However, the structural unit (a2) includes a structural unit (a2_l) in which the acid dissociable, dissolution inhibiting group is an alkoxyalkyl group.

[0061] 'component (A)

 · · Structural unit (a2)

 In the second embodiment (embodiment), the structural unit (a2) has a structural unit (a2-1) in which the acid dissociable, dissolution inhibiting group is an alkoxyalkyl group.

 Examples of the structural unit (a2_1) include a structural unit (al), that is, a unit in which a hydrogen atom of a hydroxyl group of a hydroxystyrene skeleton (main chain) is substituted with an alkoxyalkyl group. Hereinafter, when a structural unit (al) is mentioned in the description of the main chain, it is preferable that the embodiment (embodiment) is the same as the structural unit (al).

 Examples of the alkoxyalkyl group include lower alkoxy having an alkoxy group having 1 to 5 carbon atoms and an alkyl group having 1 to 5 carbon atoms, such as 1 ethoxyxyl group, 1 ethoxypropyl group, 1-methoxypropyl group, and 1_ethoxypropyl group. And an alkyl group. Among them, a structural unit substituted with a 1-ethoxyshethyl group is preferable.

[0062] In the second embodiment (embodiment), the structural unit (a2) further includes a structural unit in which the acid dissociable, dissolution inhibiting group is a tertiary alkoxycarbonyl group and / or a tertiary alkyl group. _a 2_2), preferably having.

 Thus, for the structural unit (a21) having an easily dissociable acid dissociable, dissolution inhibiting group such as an alkoxyalkyl group, a higher level of active energy is required for dissociation of the acid dissociable, dissolution inhibiting group. By having a structural unit (a2_2) which is a hardly dissociable tertiary alkoxycarbonyl group and Z or a tertiary alkyl group, both the pattern shape and the resolution can be improved.

When the structural unit (a2-1) and the structural unit (a2-2) are combined, the ratio of the structural unit (a2_l) in the component (A) is 20 45 mol%, preferably 25 40 Monore _^0/0, the structural unit (a2_2) is 5 20 mole _^0/0, preferably appropriate to the 7 15 molar%. The main chain of the structural unit (a2-2) may include a (meth) acrylic acid skeleton, a hydroxystyrene skeleton similar to the structural unit (al) represented by the general formula (I), and the like. The acid dissociation is appropriately selected depending on the type of the dissolution inhibiting group and the like. Of these, a hydroxystyrene skeleton is preferred.

 [0064] Examples of the tertiary alkoxycarbonyl group include an alkoxycarbonyl group in which the alkoxy group has 4 or 5 carbon atoms, such as a tert-butyloxycarbonyl group and a tert-amyloxycarbonyl group.

 Examples of the tertiary alkyl group include an alkyl group having 4 or 5 carbon atoms, such as a tert-butyl group and a tert-amyl group.

 Among them, a tertiary alkoxycarbonyl group is preferred, and a tert-butyloxycarbonyl group is more preferred.

 · (C) Crosslinkable polybutyl ether conjugate

 The fact that the resist composition of the second embodiment (embodiment) further contains the component (C) improves the profile shape, the depth of focus, and the effect of the present embodiment (embodiment). Is preferred.

· (C) Crosslinkable polyvinyl ether compound

 The component (C) functions as a crosslinking agent for the component (A).

 That is, the resist composition of the present embodiment is applied to a substrate or the like, and is pre-betaed at a temperature of 80 to 150 ° C., preferably 120 ° C. or more. By this heating, the components (C) and (A), for example, A crosslinking reaction with the hydroxyl group of the structural unit (al) occurs, and an alkali-insoluble or hardly-solubilized resist film is formed on the entire surface of the substrate. In the exposure step and the PEB step, (B) the component force is generated by the action of the generated acid, the cross-links are decomposed, and the exposed part changes to alkali-soluble, and the unexposed part remains unchanged in alkali-insoluble. ,. Therefore, the exposed portions can be removed by alkali development to form a resist pattern.

 Therefore, the type of component (C) is not particularly limited as long as it has such a function.

As the component (C), specifically, a compound having at least two crosslinkable butyl ether groups can be used. Specifically, ethylene glycol dibutyl ether, Triethylene glycol dibutyl ether, 1,3-butanediol dibutyl ether, tetramethylene glycol divinyl ether, neopentyl glycol divinyl ether, trimethylolpropane tributyl ether, trimethylolethane tributyl ether, hexanediol dibutyl Ether, 1,4-cyclohexanediol divinyl ether, tetraethylene glycolino resininoleate, pentaerythritol resininoleate, pentaerythritol tributyl ether, cyclohexane dimethanol divinyl Tell and the like. Among these, a crosslinkable dibutyl ethereal conjugate is more preferred.

 And, as the dibutyl ethereal conjugate, those represented by the following general formula (1) are also preferable.

[0067] [Formula 4]

CH ₂ = CH-0-R ¹ '-O-CH ^ C ^ (1)

In the general formula (1), R ¹¹ may have a substituent, and may be a branched or linear alkylene group having 1 to 10 carbon atoms, or a group represented by the following general formula (2) It is represented by The alkylene group may contain an oxygen bond (ether bond) in the main chain.

[0069] [Formula 5]

In the above general formula, R ¹⁴ is also a branched or straight-chain alkylene group having 1 to 10 carbon atoms, which may have a substituent, and the alkylene group is in the main chain. Oxygen bonds (ether bonds) are acceptable. Y is 0 or 1.

R ¹¹ includes —CH—, —CH OC H—, —CH OC H OC H—, and the general formula (2

 4 8 2 4 2 4 2 4 2 4 2 4

) Are preferred, and those represented by the general formula (2) are preferred. Particularly, those having R ¹⁴ force S methylene and Y being 1 (cyclohexanedimethanol dibutyl ether [hereinafter , Abbreviated as CH DVE]).

 The component (C) can be used alone or in combination of two or more.

The compounding amount is 0.520 parts by mass, preferably 11 to 100 parts by mass of the component (A). 10 parts by mass.

[0071] * Component (B)

 Similar to the first embodiment (embodiment).

[0072] * (D) component

 Similar to the first embodiment (embodiment).

[0073] '(E) component

 Similar to the first embodiment (embodiment).

[0074] · Other optional ingredients

 Similar to the first embodiment (embodiment).

[0075] Organic solvents

 Similar to the first embodiment (embodiment).

♦ Third Embodiment (embodiment):

 A positive resist composition according to a third embodiment (embodiment) is the positive resist composition according to the first embodiment, wherein the component (A) comprises the structural unit (al) and acid dissociation. Having a unit (a2) having a soluble dissolution inhibiting group, wherein the structural unit (a2) includes a structural unit (a2-3) in which the acid dissociable, dissolution inhibiting group is a group having an aliphatic cyclic group.

[0077] * Component (A)

 · Structural unit (a2-3)

 Here, “the acid dissociable, dissolution inhibiting group is a group having an aliphatic cyclic group” means that the acid dissociable, dissolution inhibiting group is dissociated from the resin component by the action of an acid. It shows that it is a group which has.

 By having such a structural unit (a2-3), the effect of improving the shape is improved. In particular, the resist pattern obtained by the lithography process in which the immersion process is performed tends to obtain a better rectangular shape and a higher sidewall verticality than the resist pattern obtained by the lithography process in which the immersion process is not performed. There is.

As the structural unit (a2-3), the acid dissociable, dissolution inhibiting group is a tertiary alkyl group containing an aliphatic polycyclic group and a tertiary alkyl group containing Z or an aliphatic monocyclic group. Something is No.

 [0079] Examples of the aliphatic monocyclic group include groups in which one hydrogen atom has been removed from cycloalkane. Examples of the aliphatic polycyclic group include groups obtained by removing one hydrogen atom from bicycloalkane, tricycloalkane, tetracycloalkane, and the like.

 Specifically, examples of the aliphatic monocyclic group include groups obtained by removing one hydrogen atom from cyclopentane and cyclohexane, and a cyclohexyl group is preferable.

 Examples of the aliphatic polycyclic group include groups obtained by removing one hydrogen atom from polycycloalkanes such as adamantane, norbornane, isobornane, tricyclodecane, and tetracyclododecane. Such a polycyclic group can be appropriately selected and used from a large number of groups proposed as an acid dissociable, dissolution inhibiting group in, for example, a resin for a photoresist composition of an ArF excimer laser.

 Among these, a cyclohexyl group, an adamantyl group, a nonolevonoreninole group, and a tetracyclododecanyl group are industrially available and readily preferred. Among them, a cyclohexyl group and an adamantyl group are preferred.

 [0080] The aliphatic polycyclic group-containing tertiary alkyl group and / or the aliphatic monocyclic group-containing tertiary alkyl group generally have a structure represented by the following general formula (V). A hydrogen atom of a carboxyl group of (meth) acrylic acid is bonded to a lower alkyl group such as a unit or 1-methylcyclohexyl group, 1-ethylcyclohexyl group, 1-methylcyclopentyl group, or 1-methylcyclopentyl group. Those which form an acid-dissociable tertiary alkyl ester on a substituted ring by being substituted with a substituted aliphatic monocyclic or polycyclic group are widely known. Alternatively, as in the structural unit represented by the general formula (VI) described below, a lower alkylene group having a tertiary carbon atom is bonded instead of the hydrogen atom of the methoxyl group of (meth) acrylic acid, Structural units in which an aliphatic polycyclic group or a monocyclic group is bonded to the other end of the lower alkylene group are also known. In this case, the partial force of the tertiary carbon atom of the lower alkylene group dissociates.

 Among them, the former type is preferred.

More specifically, the structural unit (a2-3) force is preferably at least one selected from the following general formulas (V) and (VI). [0082] [Formula 6]

… (V)

(In the formula, R is a hydrogen atom or a methyl group, and ¹ is a lower alkyl group.)

 [0083] [Formula 7]

 (In the formula, R is a hydrogen atom or a methyl group, and R and R are each independently a lower alkyl group.)

In the formula, R ²¹ is preferably a lower linear or branched alkyl group having 15 carbon atoms, and is preferably a methinole group, an ethyl group, a propyl group, an isopropyl group, an n-butyl group, an isobutyl group, tert Monobutyl group, pentyl group, isopentyl group, neopentyl group and the like. Among them, an alkyl group having 2 or more carbon atoms, preferably 2 to 5 carbon atoms is preferable in that acid dissociation property is higher than that of a methyl group and sensitivity can be increased. In addition, a methyl group and an ethyl group are preferable industrially.

[0085] wherein R ²² and R ²³ are each independently preferably a lower alkyl group having 1 one 5 carbon atoms It is preferred that there is. Such groups tend to be more acid dissociable than the 2-methyl-2-adamantyl group.

More specifically, it is preferable that R ²² and R ²³ are each independently a lower straight-chain or branched alkyl group similar to R ²¹ described above. Among them, the case where both R ²² and R ²³ are a methyl group is industrially preferable. Specifically, a structural unit derived from 2- (1-adamantyl) -12-propyl (meth) acrylate is exemplified. Can be.

[0086] · Preferred example of resin component (A) 1

 Among the third embodiment (embodiment), the following can be mentioned as one preferable embodiment.

 That is, the component (A) has a structural unit (al), and the structural unit (a2) is a (meth) acrylic acid in which the acid dissociable, dissolution inhibiting group is an aliphatic polycyclic group-containing tertiary alkyl group. It has a unit derived from an acid and has a structural unit (a3). More preferred is a copolymer composed of these three structural units.

[0087] Example 2 of preferred resin component (A)

 Further, of the third embodiment (embodiment), the following can be mentioned as more preferable aspects.

That is, the structural unit (a2) is intended to include structural units _(a 2-4) having an acid dissociable dissolution inhibiting group other than group having an aliphatic cyclic group.

In this embodiment, the structural unit (a2) includes a structural unit (a2-3) in which the acid dissociable, dissolution inhibiting group is a group having an aliphatic cyclic group, and further corresponds to the structural unit (a2-3). No, including the structural unit ( _a2-4 ).

With this configuration, surprisingly, when the immersion treatment step is performed, the perpendicularity of the pattern shape becomes higher, and a good rectangular pattern can be obtained. Depending on the solvent used for immersion exposure, the sensitivity S, the sensitivity of the resist pattern, etc., is degraded S. By selecting such a composition of the resist composition, better properties than the normal case without immersion exposure Is obtained. In the contact hole pattern, since the exposure area is small, a force that tends to be particularly affected by the immersion of the solvent. With this configuration, a good pattern shape can be obtained not only in L & S but also in the contact hole pattern. The reason why this effect can be obtained is apparently due to the difference in the active energy level for dissociation of the acid dissociable, dissolution inhibiting group between the structural unit (a2-3) and the structural unit (a2-4).

RCRII

 J 4

 It is expected to be one to do.

When combining the structural unit (a2-3) and the structural unit (a2-4), component (A) in terms of effect, the structural unit (a2_3) is 3-25 mole _^0/0, preferably 6- 20 Monore _^0/0, the structural units (a2_4

 RCRII

) Is 1 one 20 mole _^0/0, preferably 3 15 mol ⁰ /. It is said.

[0089] · · Structural unit (a2-4)

 The structural unit (a2-4) is not particularly limited as long as it does not correspond to the structural unit (a2_3). However, the acid dissociable, dissolution inhibiting group includes a tertiary alkoxycarbonyl group and a tertiary alkyl group. It is preferably at least one selected from a group and a crosslinking group represented by the following general formula (II).

[0090] [Formula 8]

A

 n… (Π)

(R ³ and R ⁴ are each independently a lower alkyl group, n is an integer of 13 and A represents a single bond or an n + 1 monovalent organic group.)

[0091] Examples of the tertiary alkoxycarbonyl group include a tert-butyloxycarbonyl group and a tert-amyloxycarbonyl group.

 Examples of the tertiary alkyl group include a chain tertiary alkyl group that does not contain an aliphatic polycyclic group or an aliphatic monocyclic group, such as a tert-butyl group and a tert-amyl group. -Butyl groups are preferred.

 [0092] The cross-linking group bonds between at least two constituent units. The structural unit linked by the cross-linking group has a carboxyl group, a hydroxyl group, and the like. The number of structural units linked by the crosslinking group is preferably two or three.

Examples of the lower alkyl group of R ³ and R ⁴ (preferably having 5 or less carbon atoms) include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n_butyl group, an isobutyl group, and a tert-butyl group. And a n-pentyl group.

 A is a single bond or an organic group having (n + 1) bonds, preferably a hydrocarbon group having 120 carbon atoms.

Examples of the hydrocarbon group when n is 1 include a linear or branched alkylene group, a cycloalkylene group and an arylene group.Examples of the hydrocarbon group when _n is 2 include: Examples thereof include a trivalent group in which one hydrogen atom in the above-mentioned alkylene group, cycloalkylene group or arylene group has been eliminated.

 Examples of the hydrocarbon group when n is 3 include a tetravalent group in which two hydrogen atoms in the above-mentioned alkylene group, cycloalkylene group or arylene group have been eliminated.

Particularly preferred crosslinking groups (II) are those in which A is a linear alkylene group of 2-10 and is an R ³ and R ⁴ methyl group.

 [0093] The structure of the main chain of the structural unit to be crosslinked by the crosslinking group is not particularly limited, and the same hydroxystyrene structural unit as the above structural unit (al) or the above-mentioned (meth) acrylic acid skeleton But a (meth) acrylic acid skeleton is preferred.

 That is, it is preferable to form a crosslinked structure represented by the following general formula (4).

[0095] [Formula 9]

H ₂ C

(In the above formula, R ³¹ is a methyl group or a hydrogen atom, R ³ ,

And A have the same meaning as described above. )

[0096] The crosslinked structure is preferably a crosslinked unit linked via at least two acrylic acid or methacrylic acid tertiary alkyl ester forces A (organic group or single bond). In this crosslinked structure, the ester group is converted to a carboxylic acid by the action of an acid generated by exposure. It changes to a boxyl group and changes the resin component in the exposed area to alkali solubility. On the other hand, in the unexposed area, the resin component remains alkali-insoluble because the crosslinking group remains.

 [0097] Such a crosslinked structure may be, for example, a tertiary carbon in which two or four molecules of acrylic acid or methacrylic acid or a reactive functional derivative thereof, for example, a halide of (meth) acrylic acid are bonded to each terminal with a hydroxyl group. Diesters, triesters or tetraesters having 2 to 4 ethylenically unsaturated bonds obtained by bonding to one molecule of alcohols having 2 to 4 hydroxyl groups such as diols, triols or tetrols having atoms Force induced.

 [0098] Examples of the diols include, for example, 2,3_dimethyl-2,3_butanediol, 2,3-dimethylamino-2,3_butanediol, 2,3_di-n-propyl_2,3_ Butanediol, 2,4_dimethinole-1,4_pentanediol, 2,4_jetinole-1,4, pentanediol, 2,4-di_n_propyl-1,2,4_pentanediol, 2,5-dimethinole 2,5-hexanediol, 2,5-jetinole 2,5-hexanediol, 2,5-di_n-propyl_2,5-hexanediol, 2,6 dimethyl-2,6 heptanediol, 2 Glycols such as 2,6-diethyl 2,6-heptandiol and 2,6-di-n-propyl 2,6 heptanediol, and triols such as 2,4_dimethyl-2,4-dihydroxy-3_ (2 —Hydroxypropynole) pentane, 2, 4-—Jetinole 2,4-Jihi Droxy 3_ (2-hydroxypropynole) pentane, 2,5-dimethyl-2,5-dihydroxy-3- (2-hydroxypropyl) hexane, 2,5_ethyl-2,5-dihydroxy-3_ (2-hydroxy Examples of acetonitriles such as propyl) hexane, and examples of tetrolnoles include tetrols such as erythritol, antayuritrit, and 2,3,4,5-hexanexetrol.

[0099] Among these diesters or triesters, particularly preferred are those represented by the general formula (5) [0100] [Formula 10]

(Wherein R ³¹ has the same meaning as described above, and p is 0, 1 or 2) and the general formula (6)

 [0101] [Formula 11]

Or general formula (7) [0102] [Formula 12]

… (7)

(Wherein R ³¹ has the same meaning as described above).

The acid dissociable, dissolution inhibiting group of the structural unit (a2-4) is preferably a tert-butyl group, or a crosslinking group in the diester in which p is 2 in the general formula (5).

[0104] Among Examples 2 of such a preferable resin component (A), more preferably the following two examples (Example 2)

-1, Example 2-2).

[0105] Examples of preferred resin component (A) 2_1

 In this example, the acid dissociable, dissolution inhibiting group of the structural unit (a2-3) is a tertiary alkyl group containing an aliphatic polycyclic group, and the acid dissociable, dissolvable group of the structural unit (a2-4). The resin component (A) in which the inhibitory group is a tertiary alkyl group is used.

[0106] Examples of the structural unit in which the acid dissociable, dissolution inhibiting group of the structural unit (a2-3) is a tertiary alkyl group containing an aliphatic polycyclic group include those exemplified in the description of the structural unit (a2_3). Can be used as appropriate. Above all, those having an adamantyl group are preferable, and further, in the general formula (V), a structural unit in which R ²¹ is a methyl group or an ethyl group is preferable.

When the structural unit (a2-3) and the structural unit (a2-4) are combined at this time, the ratio of each structural unit is, for example, the structural unit (a2-3) in the component (A), in terms of effect, 2 20 mole _^0/0, preferably 5-10 mol _^0/0, the structural unit (a2_4) 2-20 mole _^0/0, preferably 5- It is a 10 Monore ^_0/0.

 As the structural unit in which the acid dissociable, dissolution inhibiting group of the structural unit (a2-4) is a tertiary alkyl group, those exemplified in the description of the structural unit (a2-4) can be used as appropriate. obtain. Among them, tert-butoxystyrene structural unit in which the hydrogen atom of the hydroxyl group is substituted with t-butyl group in the hydroxystyrene skeleton, and t-butyl (meth) acrylate copolymer are preferred. Are more preferably used in combination. When these two structural units are used in combination, the molar ratio is, for example, 1: 1 to 1: 3.

 [0108] Examples of preferred resin component (A) 2_2

 In this example, the acid dissociable, dissolution inhibiting group of the structural unit (a2-3) is an aliphatic monocyclic group-containing tertiary alkyl group, and the structural unit (a2-4) is an acid dissociable, dissolution inhibiting group. As the inhibitory group, a resin component (A) having a crosslinked structure represented by the general formula (Π) is used. According to this configuration, the perpendicularity of the side wall of the pattern particularly when the immersion exposure step is performed is increased, and a very good rectangular pattern can be obtained. Good pattern shapes can be obtained not only in L & S but also in contact hole patterns.

 [0109] Examples of the structural unit in which the acid dissociable, dissolution inhibiting group of the structural unit (a2-3) is an aliphatic monocyclic group-containing tertiary alkyl group have been exemplified in the structural unit (a2-3). Can be used as appropriate. Among them, those having a cyclohexyl group are preferable, and (meth) acrylate units having a 1-methylcyclohexinole group or a 1-ethylcyclohexyl group bonded thereto are more preferable.

 [0110] The structural unit in which the acid dissociable, dissolution inhibiting group of the structural unit (a2-4) is a crosslinked structure represented by the general formula (II) is as described in the description of the structural unit (a2-4). The exemplified ones can be used as appropriate. The same applies to preferred ones.

 [0111]-Component (B)

 This is the same as in the first embodiment.

 Note that, similarly to the first embodiment (embodiment), when the component (B) contains at least one selected from a sulfoium salt-based acid generator and a diazomethane-based acid generator, the effect of the present embodiment (embodiment) can be obtained. Les, preferred in terms of.

Further, from the relationship with the acid dissociable, dissolution inhibiting group of the third embodiment (embodiment), In the embodiment (embodiment), it is preferable that the component (B) contains an onium salt-based acid generator. In the third embodiment (embodiment), even when the component (B) containing a sulfonium salt-based acid generator or a rhododium salt-based acid generator is used, the influence of the solvent or the like is not exerted. A resist composition is obtained. Among them, edonia salt-based acid generators are preferred. This is presumed to be due to the composition of component (A).

 As the acid salt-based acid generator, those similar to those exemplified in the first embodiment can be used. In the third embodiment, it is desirable that the content of the acid salt-based acid generator in the component (B) is 50% by mass or more, preferably 80% by mass or more (most preferably 100% by mass).

[0112] * (D) component

 Similar to the first embodiment (embodiment).

[0113] '(E) component

 Similar to the first embodiment (embodiment).

[0114] · Other optional ingredients

 Similar to the first embodiment (embodiment).

[0115] Organic solvents

 Similar to the first embodiment (embodiment).

[0116] ♦ Fourth embodiment (embodiment):

 A fourth embodiment (embodiment) is a positive resist composition used for a method of forming a resist pattern including a step of immersion exposure,

 It contains a resin component (A) and a compound that generates an acid upon exposure (acid generator) (B), and the component (A) is a hydroxystyrene structural unit (al) represented by the general formula (I),

 and

 Having a structural unit (a2) having an acid dissociable, dissolution inhibiting group,

This structural unit ( _a2 ) is a positive resist composition containing two or more structural units having acid dissociable, dissolution inhibiting groups having different structures.

The fourth embodiment (embodiment) differs from the first embodiment (embodiment) in that it is not essential to satisfy the condition (1). In addition, the structural unit (a2) having an acid dissociable, dissolution inhibiting group has two or more types having an acid dissociable, dissolution inhibiting group having different structures. The point is that it is essential to contain a structural unit.

 Otherwise, preferred embodiments and the like are the same as those of the first embodiment (embodiment) to the third embodiment (embodiment).

[Resist Pattern Forming Method]

 The resist pattern forming method of the present invention is a method of forming a resist pattern using the resist composition of the present invention, and includes a step of immersion exposure.

For example, first, a resist composition according to the present invention is applied to a substrate such as silicon wafer by a spinner or the like, and then pre-beta (PAB treatment) is performed.

 Note that a two-layer laminate in which an organic or inorganic antireflection film is provided between the substrate and the coating layer of the resist composition can also be used.

 Further, a two-layer laminate in which an organic antireflection film is provided on the coating layer of the resist composition can be used, and a three-layer laminate in which a lower antireflection film is further provided can be used. Further, a protective film may be formed on the coating layer of the resist composition. The steps so far can be performed using a known method. Preferably, the operating conditions and the like are appropriately set according to the composition and characteristics of the resist composition used.

[0119] Next, the resist film, which is a coating film of the resist composition obtained above, is selectively subjected to immersion exposure (Liquid Immersion Lithography) via a desired mask pattern. At this time, it is preferable to perform the exposure in a state where the space between the resist film and the lens at the lowermost position of the exposure apparatus is filled with a solvent having a refractive index larger than that of air in advance.

 The exposure light source is a KrF excimer laser.

[0120] Examples of the solvent having a refractive index larger than the refractive index of air and smaller than the refractive index of the resist composition to be used include water or a fluorine-containing inert liquid.

 Specific examples of the fluorine-containing inert liquid include C HC1 F, C F OCH, C F〇C H

 3 2 5 4 9 3 4 9 2

Liquids containing fluorine-containing compounds such as

5 5 3 7

 Such compounds can have a boiling point of 70-180 ° C, more preferably a compound having a boiling point of 80-160 ° C.

Specifically, the perfluoroalkyl compound is a perfluoroalkyl compound. Monoter compounds and perfluoroalkylamine compounds can be mentioned.

 More specifically, as the perfluoroalkyl ether compound, perfluoro (2-butyl-tetrahydrofuran) (boiling point: 102 ° C.) can be mentioned, and as the perfluoroalkylamine compound, Fluorotributylamine (boiling point 174 ° C) can be raised. Among the fluorine-containing inert liquids, those having a boiling point in the above range are preferable because the immersion liquid can be removed by a simple method after the exposure.

 Among them, water is preferable from the viewpoints of cost, safety, environmental problems and versatility.

[0121] Next, after the exposure step, PEB (post-exposure baking) is performed, and subsequently, development processing is performed using an alkaline developing solution composed of an alkaline aqueous solution. Then, water rinsing is preferably performed using pure water. The water rinsing, for example, drops or sprays water on the surface of the substrate while rotating the substrate to wash away the developing solution on the substrate and the resist composition dissolved by the developing solution.

 Then, by drying, a resist pattern patterned into a shape corresponding to the mask pattern such as the L & S or hole pattern of the resist composition can be obtained. By forming the resist pattern in this manner, a resist pattern having a fine line width, in particular, a line-and-space (L & S) pattern with a small pitch can be manufactured with good resolution.

 Here, the pitch in the line and space pattern refers to the total distance of the resist pattern width and the space width in the line width direction of the pattern.

 Example

 [0122] ♦ Production of positive resist composition

 (Example 1)

 A positive resist composition was produced as a uniform solution in which the following components (A) to (D) were dissolved in an organic solvent.

 Resin component (A) 100 parts by mass

Ore chemical formula Te,, xl: y 1: zl = 70 mole _^0/0: 5 mol _^0/0: 25 mol _^0/0 random copolymer polymer of (Mwl 2000) [0123] [Formula 13]

 [0124] Component (B)

 Acid generator represented by the following chemical formula (Bl) 3.7 parts by mass Acid generator represented by the following chemical formula (B2) 1.0 parts by mass

 [0125] [Formula 14]

 [Formula 15]

 [0126] Component (D)

 Tris 2- (2-methoxy (ethoxy)) ethylamine 0.8 parts by mass

[0127] Organic solvent

PGMEA: EL = 900 parts by mass of a mixed solvent with a mass ratio of 6: 4 (Example 2)

 A positive resist composition was manufactured as a uniform solution in which the following components (A) to (D) and a surfactant were dissolved in an organic solvent.

 Resin component (A) 100 parts by mass

(A2-1) In the following chemical formula, 22 = 61 mol%: 39 mol% of the random copolymer (MwlOOOO), and (A2-2) According to the following formula, x3: y3 = 64 monoles ⁰ / _0:36 Monore _^0/0 random copolymer and (MwlOOOO), 70: 30 resin component were mixed at a mass ratio of

[0129] [Formula 16]

 [0130] Component (B)

 Acid generator represented by the following chemical formula (B3) 3.

 Acid generator represented by the following chemical formula (B4) 1.

 The acid generator represented by the chemical formula (B1) 1.0 part by mass

 [0131] [Formula 17]

[Formula 18]

 … (B4)

[0132] Component (C)

 CHDVE 3.0 parts by mass

[0133] Component (D)

 0.2 parts by mass of triethanolamine

 Triisopropanolamine 0.05 parts by mass

[0134] Surfactant

 Fluorine-containing surfactant Megafax XR-104 (manufactured by Dainippon Ink) 0.05 parts by mass [0135] Organic solvent

 PGMEA 900 parts by mass

(Example 3)

 A positive resist composition was prepared as a uniform solution in which the following components (A) to (D) and a surfactant were dissolved in an organic solvent.

 Resin component (A) 100 parts by mass

(A3-1) in the following chemical formula, x4: y4: z4: y5 : z5 = 72.5 mol%: 5 mol%: 7.5 mol _^0/0: 12.5 mole _^0/0: 2.5 mole _^0/0 each unit of randomly Polymer (Mwl 2000

) Is a resin component

[0137] [Formula 19]

[0138] Component (B)

 2.19 parts by mass of the acid generator represented by the chemical formula (Bl)

 The acid generator represented by the chemical formula (B2) 0.18 parts by mass

[0139] Component (D)

 Triethanolamine 0.126 mass 咅

 Triisopropanolamine 0.108 parts by mass

[0140] Surfactant

 Fluorine-containing surfactant Megafax XR-104 (manufactured by Dainippon Ink) 0.05 parts by mass

[0141] Organic solvent

 PGMEA: EL = 900 parts by mass of 6: 4 mixed solvent

[0142] (Example 4)

 A poly-type resist composition was prepared as a uniform solution in which the following components (A) to (E) and a surfactant were dissolved in an organic solvent.

 Resin component (A) 100 parts by mass

(A4-1) in the following chemical formula, x6: y6: z6: w = 73.6 mole _^0/0: 6.6 Monore ⁰ / _0:15 model %: A polymer having 5 mol% of each unit at random (resin component having Mw of 30,000)

 [0144] Component (B)

 3.0 parts by mass of an acid generator represented by the following chemical formula (B5)

[0145] [Formula 21]

 … CB5)

 [0146] Component (D)

 Triethanolamine 0.15 mass%

 [0147] Component (E)

 Phenylphosphonic acid 0.158 parts by mass

 [0148] Surfactant

 Fluorosilicon-based surfactant Megafax R-60 (Dainippon Ink)

0.02 mass 咅! ^

 [0149] Organic solvent

 900 parts by mass of ethyl lactate

[0150] (Comparative Example 1) In the photoresist composition of Example 1, the resin component (A) was copolymerized with the following structural formula.

 x7 + y7 = 20 mol%

 z7 tens t7 = 80 mol% ♦ Evaluation method 1 (Evaluation of Examples 1-4 and Comparative example 1)

 (Test method 1: Sensitivity measurement)

 (i) Formation of resist pattern using lithographic process by normal exposure: XI

 First, using a positive resist composition, a resist pattern was formed using a lithographic process by ordinary exposure.

 Organic anti-reflective coating composition: Product name DUV42P (made by Blue's Science) is applied on an 8-inch diameter silicon wafer using a spinner, baked on a hot plate at 185 ° C for 60 seconds and dried. As a result, an organic antireflection film having a thickness of 65 nm was formed.

 Then, the positive resist composition is applied on the anti-reflection film using a spinner, pre-betaed (PAB) for 90 seconds on a hot plate under the conditions shown in Table 1 below, and dried to obtain a reflection. A 350 nm-thick resist film was formed on the prevention film.

 Next, selective exposure was performed using a KrF excimer laser (248 nm) with a KrF lithography system S203B (Nikon NA numerical aperture = 0.68, σ = 2/3 annular illumination) through a binary mask as a reticle. went.

Next, PEB treatment was performed for 90 seconds under the conditions shown in Table 1, and further development was performed at 23 ° C with an alkaline developer for 60 seconds. As the alkali developing solution 2.38 wt _^0/0 tetramethylammonium Niu arm hydroxamate An aqueous sid solution was used.

 In this way, a resist pattern with a 150 nm line and space of 1: 1 was formed, and the sensitivity (Eop): X1 at that time was determined.

(Ii) Formation of Resist Pattern Using Simulated Immersion Lithography Step: X2

 A pattern was formed in the same manner as in the above (i) except that the following simulated immersion exposure treatment was performed, and the sensitivity X2 was obtained.

 In the simulated immersion exposure processing, pure water was continuously dropped on the resist film at 23 ° C for 2 minutes while rotating the silicon wafer with the resist film between selective exposure and PEB processing. .

 [0154] The PAB conditions and PEB conditions of the above Examples and Comparative Examples are as follows. These conditions were optimized for each resist composition.

[Table 1] Example 1 Example 2 Example 3 Example 4 Comparative 1

PAB condition temperature () 125 100 125 140 100

PEB condition temperature (^ 0) 1 10 1 10 1 10 140 1 10

[0156] The results are shown in Table 2.

[0157] [Table 2]

[0158] In Example 2 according to the second embodiment (embodiment); In Examples 1, 3, and 4 according to the third embodiment (embodiment), the absolute value was 5 or less and the sensitivity deterioration was small. It was good.

 (Test method 2: Evaluation of pattern shape)

For the L & S pattern (both with and without immersion treatment) formed in Test Method 1, Each was observed with a scanning electron microscope (SEM), and the cross-sectional shape of the pattern was observed.

 The hole pattern was also evaluated. For the evaluation of the hole pattern, use a halftone mask in which holes with a diameter of 200 nm were formed. A pattern was formed in accordance with Test Method 1 except that was formed.

 Table 3 shows the results.

[Table 3]

ヽ

 ^

 Comparative Example Example Example Example Example 14321

 'Ta Slight Slight' 'Ta Slight' T-Shape or I-Shape: LS Raha / Hari, Sori & Ri: // / / ---- Shape Rectangle

 The straightness is high and the side wall is vertical.

 The young part has a dry head, and the part has a vertical part. The part is slightly T-head.

 But it's round

 The rectangular shape is available.

 Very good rectangular shape

 Takhokutoruri]--Ta. Slightly a little bit, a little bit, / * Type: /-part is round and rectangular part is round and rectangular part is round and rectangular head

 (瀆) No immersion

 The side wall perpendicularity is high.

 The part of Takuta Waka's dried head Kurbasoko is slightly different. The head of the head-, (

 Overhang e. The shape is round and the rounded part is no longer round.

 Rikuho (soaked) shape has a performance

 Very good rectangular shape

As shown in Table 3, in the comparative example, the pattern shape became T-top by immersion in water, and it was confirmed that the influence of the immersion solvent was large, whereas the example according to the present invention was confirmed. In both cases, no significant change in pattern shape was observed with or without the immersion treatment. It was.

 Above all, surprisingly, in Examples 3 and 4, it was confirmed that the immersion treatment increased the perpendicularity of the pattern shape and provided a good rectangular pattern.

 Therefore, it was confirmed that better characteristics could be obtained by performing immersion exposure by selecting the composition of the resist composition where the deterioration of sensitivity, resist pattern, etc. was concerned by the solvent used for immersion exposure did it.

[0162] (Example 5)

 Using the same resist composition as in Example 2, evaluation was made by the following evaluation method 2.

(Example 6)

 A resist layer was formed using the same resist composition as in Example 2, a protective film material was further applied thereon, and a laminate provided with a top coat (protective film) was evaluated by the following evaluation method 2. .

 The protective film material is a resin mixture of Demnum S-20 (product name, manufactured by Daikin Industries, Ltd.) and CYTOP (product name, manufactured by Asahi Glass Co., Ltd.). It was dissolved in fluorotributylamine to give a resin concentration of 2.5% by mass.

(Example 7)

 Using the same resist composition as that in Example 3, evaluation was performed by the following evaluation method 2.

(Example 8)

 Regarding a laminate in which a resist layer was formed using the same resist composition as in Example 3 and a top coat was further provided thereon using the same protective film material as that used in Example 6 above. Evaluation was performed by the following evaluation method 2.

♦ Evaluation Method 2 (Evaluation of Examples 5-8)

 First, an organic anti-reflective coating composition: product name DUV42P (manufactured by Blue Science) is applied on an 8-inch diameter silicon wafer using a spinner, and baked at 185 ° C for 60 seconds on a hot plate. Then, an organic antireflection film having a thickness of 65 nm was formed by drying.

Then, the positive resist composition obtained above is applied on an antireflection film using a spinner, and is pre-betaed on a hot plate at a temperature condition shown below for 90 seconds. By drying, a resist film having a thickness of 350 nm was formed on the antireflection film.

In Examples 6 and 8, the protective film material was further spin-coated on the resist film, and heated at 90 ° C. for 60 seconds to form a protective film having a thickness of 37 nm. .

[0168] Then, as the immersion exposure, a two-beam interference exposure machine LEIES193-1 (Nikon) was used.

Immersion two-beam interference exposure using two beams of 248 nm wavelength with prism and water

. A similar method is also disclosed in the aforementioned Non-patent Document 2, and is known as a method for easily obtaining a line-and-space (L & S) pattern at a laboratory level.

 Next, PEB treatment was performed for 90 seconds under the following temperature conditions, and further development was performed at 23 ° C with an alkaline developer for 60 seconds. As the alkaline developer, an aqueous solution of 2.38% by mass of tetramethylammonium hydroxide was used.

 [0169] The temperature conditions of the pre-beta and the PEB treatment were the same as in Examples 5 and 6 of Example 2 shown in Table 1 above. Examples 7 and 8 were the same as Example 3 shown in Table 1 above.

 [0170] In this way, an attempt was made to form a resist pattern in which the L & S of 64.5 nm was 1: 1. In each of the examples, the resolution could be resolved.

 Then, each was observed with a scanning electron microscope (SEM), and the cross-sectional shape of the pattern was observed. The results are shown in Table 4.

 [0171] [Table 4]

[0172] As shown in Table 4, in Examples 5 to 8, a rectangular 64.5 nm L & S pattern could be formed using a KrF excimer laser. Also, a pattern could be formed by immersion exposure without forming a top coat. Industrial applicability

 The method for forming a positive resist composition and a resist pattern of the present invention is used in a method for forming a resist pattern including a step of immersion exposure.

Claims

Claims A positive resist composition used in a method for forming a resist pattern including a step of immersion exposure, wherein the positive resist composition satisfies the following conditions (1) and (2). (1) Sensitivity when using the positive resist composition to form a resist pattern in which a 150 nm line and space is one-to-one by a lithography process of normal exposure using a KrF excimer laser having a wavelength of 248 nm as a light source. In the same step as the lithography step of the normal exposure using the KrF excimer laser having the wavelength of 248 nm as a light source, the solvent of the above immersion exposure is applied between the selective exposure and the post-exposure bake (PEB). Assuming that the sensitivity at the time of forming a resist pattern in which a 150 nm line and space is one-to-one by a simulated immersion lithography process in which the process of contacting with a film is reduced is X2, [(X2 / XD-1 The absolute value of X 100 is not more than 5. (2) The positive resist composition contains a resin component (A) and a compound capable of generating an acid upon exposure (acid generator) (B). The ingredients are as follows Having a hydroxystyrene structural unit (al) represented by the general formula (I).

 [Chemical 1]

(In the formula, R represents a hydrogen atom or a methyl group, and m represents an integer of 1 to 3.)

[2] The positive resist composition according to claim 1, wherein

 The component (A) has a structural unit (a2) having an acid dissociable, dissolution inhibiting group, and the structural unit (a2) includes two or more structural units having an acid dissociable, dissolution inhibiting group having different structures. A positive resist composition to be contained.

[3] The positive resist composition according to claim 1 or 2, The component (A) has a structural unit (a2) having an acid dissociable, dissolution inhibiting group, and the structural unit (a2) is a structural unit (a2-1) in which the acid dissociable, dissolution inhibiting group is an alkoxyalkyl group. A) a positive resist composition comprising:

[4] The positive resist composition according to claim 3,

 The positive resist composition further comprises the structural unit (a2), wherein the acid dissociable, dissolution inhibiting group is a tertiary alkoxycarbonyl group and / or a tertiary alkyl group.

 [5] The positive resist composition according to claim 1 or 2, further comprising (C) a crosslinkable polyvinyl ether compound.

 [6] The positive resist composition according to claim 1 or 2,

 The component (A) has a unit (a2) having an acid dissociable, dissolution inhibiting group, and the constituent unit (a2) is a group in which the acid dissociable, dissolution inhibiting group has an aliphatic cyclic group. A positive resist composition containing a unit (a2-3).

[7] The positive resist composition according to claim 6, wherein the acid dissociable, dissolution inhibiting group of the structural unit (a2-3) is an aliphatic polycyclic group-containing tertiary alkyl group. And / or a positive resist composition which is an aliphatic monocyclic group-containing tertiary alkyl group.

[8] The positive resist composition according to claim 6, wherein the structural unit (a2) 1 a structural unit having an acid dissociable, dissolution inhibiting group other than the group having an aliphatic cyclic group ( a2-4) A positive resist composition comprising:

[9] The positive resist composition according to claim 8, wherein the acid dissociable, dissolution inhibiting group of the structural unit (a2-4) is a tertiary alkoxycarbonyl group or a tertiary alkyl group. And a positive resist composition of at least one kind selected from crosslinking groups represented by the following general formula (II).

 [Formula 2]

• (II) (R ³ and R ⁴ are each independently a lower alkyl group, n is an integer of 13 and A represents a single bond or an n + 1 monovalent organic group.)

[10] The positive resist yarn composition according to claim 9, wherein

The acid dissociable, dissolution inhibiting group of the structural unit ( _a2-3 ) is an aliphatic polycyclic group-containing tertiary alkyl group,

The structural unit _(a 2 - 4) The positive resist composition is a tertiary alkyl group of outside Moto以the acid dissociable dissolution inhibiting group having the aliphatic cyclic group.

[11] The positive resist composition according to claim 9,

The acid dissociable, dissolution inhibiting group of the structural unit ( _a2-3 ) is an aliphatic monocyclic group-containing tertiary alkyl group,

A positive resist composition wherein the acid dissociable, dissolution inhibiting group of the structural unit ( _a2-4 ) has a crosslinked structure represented by the general formula (II).

[12] The positive resist composition according to claim 1 or 2,

 A positive resist composition comprising (B) an acid generator, wherein the component (B) contains at least one selected from a sulfonium salt-based acid generator and a diazomethane-based acid generator.

13. The positive resist composition according to claim 6, wherein the positive resist composition contains (B) an acid generator, and the component (B) contains an onium salt-based acid generator.

[14] A positive resist composition used for a resist pattern forming method including a step of immersion exposure,

 A resin component (A) and a compound capable of generating an acid upon exposure (acid generator) (B), wherein the component (A) is a hydroxystyrene structural unit (al) represented by the following general formula (I),

 [Formula 3]

_m '.. (I) (In the formula, R represents a hydrogen atom or a methyl group, and m represents an integer of 1 to 3.)

 and

 Having a structural unit (a2) having an acid dissociable, dissolution inhibiting group,

This positive resist composition contains two or more structural units ( _a 2) having acid dissociable, dissolution inhibiting groups having different structures.

[15] A method for forming a resist pattern using the resist composition according to claim 1, 2, or 14, comprising a step of immersion exposure.

[16] In the step of immersion exposure, after forming a resist film made of a resist composition, the space between the resist film and the lowermost lens of the exposure apparatus is filled with a solvent having a refractive index larger than that of air. 16. The method for forming a resist pattern according to claim 15, wherein: