JP2011197150A - Radiation-sensitive composition and resist pattern forming method using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a radiation-sensitive composition that is used for double patterning and suitably used also for a liquid (such as water) immersion exposure process.SOLUTION: This radiation-sensitive composition is used in a resist pattern forming method including double patterning as a predetermined process. The radiation-sensitive composition contains (a) polymer containing repeating unit having a lactone structure or cyclic carbonate structure and also having acid-labile group, (b) radiation-sensitive acid generator, and (c) solvent.

Description

  The present invention relates to a positive-type radiation-sensitive composition and a resist pattern forming method using the same, and more particularly, to a radiation-sensitive composition that is used for patterning by double exposure and also suitable for immersion exposure processes such as water. The present invention relates to a conductive composition and a resist pattern forming method using the same.

  In the field of microfabrication represented by the manufacture of integrated circuit elements, in order to obtain a higher degree of integration, recently, lithography technology capable of microfabrication at a level of 0.10 μm or less is required. In the conventional lithography process, near ultraviolet rays such as i-line are generally used as radiation, and it is said that fine processing at the subquarter micron level is extremely difficult with this near ultraviolet rays. Therefore, in order to enable microfabrication at a level of 0.10 μm or less, use of radiation having a shorter wavelength is being studied. Examples of such short-wavelength radiation include an emission line spectrum of a mercury lamp, far ultraviolet rays typified by an excimer laser, X-rays, and electron beams. Among these, KrF excimer laser (wavelength 248 nm) or ArF excimer laser (wavelength 193 nm) has attracted attention.

  As a resist suitable for irradiation with such an excimer laser, a component having an acid-dissociable functional group and a component that generates an acid upon irradiation with radiation (hereinafter also referred to as “exposure”) (hereinafter referred to as “acid generator”) Many resists that utilize the chemical amplification effect (hereinafter referred to as “chemically amplified resist”) have been proposed. As the chemically amplified resist, for example, a resist containing a resin having a tert-butyl ester group of carboxylic acid or a tert-butyl carbonate group of phenol and an acid generator has been proposed. In this resist, a tert-butyl ester group or a tert-butyl carbonate group is dissociated by the action of an acid generated by exposure to become an acidic group composed of a carboxyl group or a phenolic hydroxyl group. This utilizes the phenomenon of being easily soluble in an alkali developer.

  In such a lithography process, further fine pattern formation (for example, a fine resist pattern having a line width of about 45 nm) will be required in the future. As means for achieving such fine pattern formation, it is conceivable to shorten the wavelength of the light source of the exposure apparatus or increase the numerical aperture (NA) of the lens. However, in order to shorten the light source wavelength, a new expensive exposure apparatus is required. In addition, the increase in the numerical aperture (NA) of the lens has a problem that the depth of focus decreases even if the resolution is increased because the resolution and the depth of focus are in a trade-off relationship.

  Recently, a liquid immersion lithography (liquid immersion lithography) method has been reported as a lithography technique that can solve such problems. In this method, at the time of exposure, a liquid high refractive index medium (immersion exposure liquid) such as pure water or a fluorine-based inert liquid having a predetermined thickness on at least the resist film between the lens and the resist film on the substrate. It is a method of interposing. According to this method, by replacing the exposure optical path space, which has conventionally been an inert gas such as air or nitrogen, with a liquid having a higher refractive index (n), a shorter wavelength can be obtained using a light source having the same exposure wavelength. As in the case of using the above light source and the case of using a high NA lens, high resolution is achieved and there is no reduction in the depth of focus. If such immersion exposure is used, it is possible to realize the formation of a resist pattern that is low in cost, excellent in resolution, and excellent in depth of focus by using a lens mounted on an existing apparatus. It is attracting attention and is being put to practical use.

However, it is said that the progress of the exposure technique by the immersion exposure method is limited to 45 nmhp, and technical development for the 32 nmhp generation that requires further fine processing is being performed.
In recent years, along with the demand for higher complexity and higher density of such devices, sparse line patterns such as double patterning (hereinafter also referred to as “DP”) or double exposure (hereinafter also referred to as “DE”) or Techniques for patterning 32 nm LS by overlapping isolated trench patterns shifted by a half cycle have been proposed (see, for example, Non-Patent Documents 1 and 2).

As an example of a technique for patterning 32 nm LS, Non-Patent Document 2 discloses that a 32 nm line having a pitch of 1: 3 is formed, a hard mask such as SiO ₂ is processed by etching, and then a resist pattern and a half layer of the first layer are formed. It is disclosed that a 32 nm line having a pitch of 1: 3 is similarly formed at a position shifted by a period, and a HM is processed again by etching to finally form a 32 nm line having a pitch of 1: 1. .

SPIE 2006 61531K 3rd International Symposium Immersion Lithography PO-11

  However, although there are some proposed processes, the proposal of specific materials that can be suitably used for patterning by double exposure using such an immersion exposure process is still insufficient. It is. Also, in the proposed process, after forming the first resist pattern, when forming the second resist pattern, the final target fine pattern cannot be obtained unless the resolution of the second resist is sufficient. There was a problem.

  The present invention has been made in view of such problems of the prior art, and the problem is that it can be suitably used for an immersion exposure process. In patterning by double exposure, It is providing the radiation sensitive composition used suitably in order to form a 2nd resist pattern.

  Further, the problem is that patterning by double exposure can be suitably employed in the immersion exposure process without causing insufficient resolution and insufficient DOF margin when forming the second resist pattern. It is to provide a resist pattern forming method.

  As a result of intensive studies to achieve the above-mentioned problems, the present inventors have found that the above-mentioned problems can be achieved by containing predetermined constituents, and the present invention has been completed.

  In addition, the second resist formed using the radiation-sensitive composition of the present invention has a very high resolving power, and does not collapse even in a very fine pattern of less than 30 nm LS, ensuring a sufficient DOF margin in device manufacturing. The present inventors have succeeded in lithography and found that the above-mentioned problems can be achieved, thereby completing the present invention.

  That is, according to the present invention, the following radiation sensitive composition and resist pattern forming method are provided.

  [1] A step (1) of forming a first resist pattern on a substrate using the first radiation-sensitive composition, and the first resist pattern with respect to the second radiation-sensitive composition And insolubilizing step (2), and using the second radiation-sensitive composition, forming a second resist pattern on the substrate on which the first resist pattern is formed (3), A radiation-sensitive composition used as a second radiation-sensitive composition in a resist pattern forming method comprising a polymer (a), a radiation-sensitive acid generator (b), and a solvent (c), A radiation-sensitive composition, wherein the polymer (a) contains a repeating unit having a lactone structure or a cyclic carbonate structure.

  [2] The polymer (a) includes at least one repeating unit (a2) selected from the group consisting of the following general formulas (1-1) to (1-7) [1] The radiation-sensitive composition as described in 1.

In the general formulas (1-1) to (1-7), R ¹ represents a hydrogen atom, a methyl group, or a trifluoromethyl group. In the general formula (1-1), R ² represents a hydrogen atom or a substituted or unsubstituted alkyl group having 1 to 4 carbon atoms, and l represents an integer of 1 to 3. In the general formulas (1-4) and (1-5), R ³ represents a hydrogen atom or a methoxy group. In the general formulas (1-2) and (1-3), A represents a single bond or a methylene group, and m represents 0 or 1. In the general formulas (1-3) and (1-5), B represents an oxygen atom or a methylene group. In the general formula (1-7), R ^c1 represents a single bond or a divalent linking group. R ^cc represents a monovalent organic group having a cyclic carbonate structure.

  [3] The ratio [2], wherein the ratio of the repeating unit (a2) contained in the polymer (a) is 1 to 80 mol% with respect to 100 mol% in total of the repeating units contained in the polymer (a). The radiation-sensitive composition as described in 1.

  [4] The radiation-sensitive composition according to [1] to [3], wherein the polymer (a) has a repeating unit represented by the following general formula (2).

In General Formula (2), R ¹ represents a hydrogen atom, a methyl group, or a trifluoromethyl group, and R ^{4 s} are independently of each other a linear or branched alkyl group having 1 to 4 carbon atoms, or A monovalent alicyclic hydrocarbon group having 4 to 20 carbon atoms, or a divalent alicyclic hydrocarbon having 4 to 20 carbon atoms formed by bonding any two R ⁴ to each other The remaining R ⁴ represents a linear or branched alkyl group having 1 to 4 carbon atoms, or a monovalent alicyclic hydrocarbon group having 4 to 20 carbon atoms or a derivative thereof.
[5] A step (1) of forming a first resist pattern on a substrate, a step (2) of insolubilizing the first resist pattern with respect to a second radiation-sensitive composition, and the [1 Step (3) of forming a second resist pattern on the substrate on which the first resist pattern is formed using the radiation-sensitive composition according to any one of [4] to [4]. A resist pattern forming method.
[6] The first resist pattern has a line portion and a space portion, the second resist pattern has a line portion and a space portion, the line portion of the first resist pattern, The resist pattern forming method according to [5], wherein the second resist pattern is formed so that the line portions of the second resist pattern intersect each other.
[7] The first resist pattern has a line portion and a space portion, the second resist pattern has a line portion and a space portion, and the line portion of the first resist pattern; The resist pattern forming method according to [5], wherein the second resist pattern is formed so that the line portion of the second resist pattern is parallel to the line portion.
[8] The resist pattern forming method according to any one of [5] to [7], wherein the step (2) is a step of applying heat of 100 ° C. to 250 ° C. to the first resist pattern.

  Further, according to the resist pattern forming method of the present invention, in double exposure, particularly in patterning a photoresist called double patterning, when forming the second resist pattern, insufficient resolution and insufficient DOF margin occur. In addition, there is an effect that it can be suitably employed in the immersion exposure process.

  BEST MODE FOR CARRYING OUT THE INVENTION The best mode for carrying out the present invention will be described below, but the present invention is not limited to the following embodiment, and is based on the ordinary knowledge of those skilled in the art without departing from the gist of the present invention. It should be understood that modifications and improvements as appropriate to the following embodiments also fall within the scope of the present invention.

1. Resist pattern formation method:
The resist pattern forming method of the present invention is a method including steps (1) to (3). Hereinafter, an embodiment of a resist pattern forming method of the present invention will be described with reference to the drawings.

1-1. Step (1):
1 to 3 and FIG. 8 are cross-sectional views schematically showing a substrate at each stage of step (1) in the resist pattern forming method of the present embodiment. In step (1), first, as shown in FIG. 1, the first resist layer 2 is formed by applying the first radiation-sensitive composition onto the substrate 1. Next, as shown in FIGS. 8 and 2, the radiation that has passed through the mask 4 having a predetermined pattern (arrow L in FIG. 8) is optionally passed through an immersion exposure liquid 3 such as water. By exposing the resist layer 2, an alkali developing portion 5 as shown in FIG. 2 is formed. Thereafter, development is performed to form a first resist pattern 12 having a line portion 12a and a space portion 12b (line and space is 1: 3: 1L3S) on the substrate 1 as shown in FIG. .

1-1-1. Formation of the first resist layer:
The first resist layer 2 can be formed by applying a coating liquid made of the first radiation-sensitive composition on the substrate 1. The method for applying is not particularly limited, and an appropriate application method such as spin coating, cast coating, roll coating or the like can be used. The thickness of the first resist layer to be formed is not particularly limited, but is usually 10 to 1,000 nm, and preferably 10 to 500 nm.

  Moreover, after apply | coating the coating liquid which consists of a 1st radiation sensitive composition, as needed, it precoats (Pre-Bake. Hereafter, it is also described as "PB."), And a coating film (coating liquid) The solvent inside may be volatilized. The heating conditions for PB are appropriately selected depending on the composition of the first radiation-sensitive composition, but are usually 10 to 200 seconds at 30 to 200 ° C. and 15 to 120 seconds at 50 to 150 ° C. It is more preferable that it is 30 to 100 seconds at 60 to 120 ° C.

(I) First radiation-sensitive composition The first radiation-sensitive composition is a radiation-sensitive composition described later. The polymer (A1), the radiation sensitive acid generator (C), the solvent (D) and the like contained in the first radiation sensitive composition will also be described later.

(Ii) The substrate substrate is not particularly limited, and a conventionally known substrate such as a silicon wafer or a wafer coated with aluminum can be used. In order to maximize the potential of the first radiation-sensitive composition, it is used, for example, as disclosed in Japanese Patent Publication No. 6-12452 and Japanese Patent Application Laid-Open No. 59-93448. An organic or inorganic antireflection film can also be formed on the substrate.

1-1-2. exposure:
As shown in FIG. 8, the radiation that has passed through the mask 4 having a predetermined pattern (arrow L in FIG. 8) is exposed to the first resist layer 2. Form. At this time, radiation may optionally be passed through the immersion exposure liquid 3 such as water or a fluorine-based inert liquid.

  In the resist pattern forming method of the present embodiment, the “mask of a predetermined pattern” is, for example, the width of a strip-shaped portion (space portion) exposed by radiation that has passed through the mask is the width of an unexposed strip-shaped portion (line portion). This is a mask having a pattern in which the exposed strip-shaped portions and the unexposed strip-shaped portions are alternately arranged. That is, the resist pattern formed by this mask is a mask that becomes a line-and-space (1L3S) pattern in which the width of the line portion and the width of the space portion are 1: 3.

  The radiation used for exposure is visible light, ultraviolet light, far ultraviolet light, X-rays, charged particle beams, depending on the type of radiation-sensitive acid generator (B) contained in the first radiation-sensitive composition. Etc. are selected as appropriate. Among these, far ultraviolet rays by ArF excimer laser (wavelength 193 nm), KrF excimer laser (wavelength 248 nm), etc. are preferable, and far ultraviolet rays by ArF excimer laser (wavelength 193 nm) are particularly preferable. Further, the exposure conditions such as the exposure amount are appropriately selected according to the blending composition of the first radiation-sensitive composition, the type of additive, and the like.

  Furthermore, it is preferable to perform a heat treatment (Post-Exposure Bake. Hereinafter, also referred to as “PEB”) after exposure. By performing PEB, the dissociation (elimination) reaction of the acid labile group in the first radiation-sensitive composition can proceed smoothly. The heating conditions for PEB are appropriately selected depending on the composition of the first radiation-sensitive composition, but are usually 30 to 200 ° C. for 30 to 120 seconds and 50 to 170 ° C. for 40 to 100 seconds. Is preferred.

1-1-3. First resist pattern formation:
By developing the first resist layer 2 with a developer that is an alkaline aqueous solution, the alkali developing portion 5 is dissolved, and a first resist pattern 12 having a line portion 12a and a space portion 12b as shown in FIG. Can be formed. In addition, after developing, it is usually washed with water and dried.

(1) Developer As preferred examples of the developer, sodium hydroxide, potassium hydroxide, sodium carbonate, sodium silicate, sodium metasilicate, ammonia, ethylamine, n-propylamine, diethylamine, di-n-propylamine, Triethylamine, methyldiethylamine, ethyldimethylamine, triethanolamine, tetramethylammonium hydroxide, pyrrole, piperidine, choline, 1,8-diazabicyclo- [5.4.0] -7-undecene, 1,5-diazabicyclo- [ 4.3.0] An alkaline aqueous solution in which an alkaline compound such as 5-nonene is dissolved can be mentioned. These alkaline compounds may be used alone or in combination of two or more.

  The concentration of the alkaline compound in the developer is usually 10% by mass or less. If the concentration of the alkaline compound is more than 10% by mass, the unexposed area may be dissolved in the developer.

  Moreover, an organic solvent can also be added to a developing solution. Specific examples of the organic solvent include acetone, methyl ethyl ketone, methyl i-butyl ketone, cyclopentanone, cyclohexanone, 3-methylcyclopentanone, 2,6-dimethylcyclohexanone and the like ketones; ethyl acetate, n-butyl acetate, acetic acid Esters such as i-amyl; aromatic hydrocarbons such as toluene and xylene, as well as phenol, acetonylacetone, dimethylformamide and the like. In addition, you may use these organic solvents individually by 1 type or in combination of 2 or more types.

  The use ratio of the organic solvent in the developer is preferably 100 parts by volume or less with respect to 100 parts by volume of the alkaline aqueous solution. If the use ratio of the organic solvent is more than 100 parts by volume, the developability may be reduced, and the development residue in the exposed part may increase. Further, an appropriate amount of a surfactant or the like may be added to the developer.

(2) Development method There is no restriction | limiting in particular as a development method, Although a conventionally well-known method can be used, It is preferable to use development methods, such as a paddle type, LD nozzle type, and GP nozzle type. The development time is preferably 10 to 90 seconds.

1-2. Step (2):
Step (2) is a step of insolubilizing the first resist pattern with respect to the second radiation-sensitive composition. In the resist pattern forming method of the present embodiment, the first resist pattern 12 is formed. It is preferable to heat or irradiate (exposure) the entire wafer, particularly preferably.

  FIG. 4 is a cross-sectional view schematically showing the substrate in the state irradiated with radiation in the step (2). The line portion 12a of the first resist pattern 12 formed in the step (1) is baked by heating at a temperature of 120 ° C. or higher (hereinafter also referred to as “PDB”); The line part 22a of the first resist pattern 22 insolubilized with respect to the second radiation-sensitive composition is obtained by at least one of the irradiation treatments.

  As conditions for PDB, the heating temperature is 100 to 250 ° C. for 60 to 150 seconds, preferably the heating temperature is 120 to 240 ° C. or less for 30 to 120 seconds, and more preferably the heating temperature is 140 to 220 ° C. or less. 15 to 100 seconds. The heating temperature of the PDB is preferably higher than the PEB temperature when forming the first resist pattern.

  As conditions for irradiating radiation, it is preferable to use radiation, and it is more preferable to perform exposure using radiation having a wavelength of 300 nm or less. Moreover, as an exposure amount, it is preferable to irradiate radiation with an exposure amount 2 to 20 times the optimum exposure amount for forming the first resist pattern 12.

Moreover, the 1st resist in which the line part 12a of the 1st resist pattern 12 was inactivated with respect to light and a heat, and was insolubilized with respect to the 2nd radiation sensitive composition by irradiating with radiation. It can also be the line portion 22a of the pattern 22. Specific examples of the lamp used for UV curing include Ar ₂ lamp, KrCl lamp, Kr ₂ lamp, XeCl lamp, Xe ₂ lamp (manufactured by Ushio Electric Co., Ltd.) and the like. These inactivation methods may be used alone or in combination of two or more.

  In addition, the first resist pattern 12 may be coated with an insolubilized resin composition. As an insolubilized resin composition, for example, there is one containing a hydroxyl group-containing resin and an alcohol solvent and having a property of being insolubilized by baking. More specifically, a resin composed of a monomer having an amide bond in the molecule (having an amide group) and a monomer having a hydroxyl group, a monovalent alcohol solvent having 1 to 8 carbon atoms, and The thing containing a crosslinking component according to this can be mentioned. The insolubilized resin composition is applied, baked, and then developed to form a pattern insolubilized with respect to the second radiation-sensitive composition.

  In the present specification, “inert to light” means that the radiation-sensitive composition is not exposed to radiation or the like. That is, the line portion 22a of the first resist pattern 22 does not become alkali-soluble even when exposed. Further, “inactive to heat” means that the resist pattern is not deteriorated by heating at the time of forming the second resist pattern.

1-3. Step (3):
5 to 7 and 8 are cross-sectional views schematically showing the substrate at each stage of step (3) in the resist pattern forming method of the present embodiment. In step (3), first, as shown in FIG. 5, the second radiation-sensitive composition is applied to the space portion 22 b of the first resist pattern 22 on the substrate 1 to thereby form the second resist layer. 32 is formed. Next, as shown in FIGS. 8 and 6, the radiation that has passed through the mask 4 having a predetermined pattern (arrow L in FIG. 8) is optionally passed through an immersion exposure liquid 3 such as water. By exposing the resist layer 32, an alkali developing portion 35 as shown in FIG. 6 is formed. Thereafter, development is performed to form a line portion 42 a of the second resist pattern 42 in the space portion 22 b of the first resist pattern 22 formed on the substrate 1.

1-3-1. Formation of second resist layer:
The second resist layer 32 can be formed by applying a coating solution made of the second radiation-sensitive composition from above the first resist pattern 22 formed on the substrate 1. The coating solution made of the second radiation-sensitive composition applied from above the first resist pattern 22 enters the space portion 22b of the first resist pattern 22, and as shown in FIG. 22b is filled with a coating solution made of the second radiation-sensitive composition.

  The application method is not particularly limited, and can be performed by an appropriate application means such as spin coating, cast coating, roll coating or the like. The thickness of the second resist layer 32 is not particularly limited, but is usually 10 to 1,000 nm, preferably 10 to 500 nm, like the first resist layer.

  Moreover, after apply | coating the coating liquid which consists of a 2nd radiation sensitive composition, the solvent in a coating film (coating liquid which consists of a 2nd radiation sensitive composition) is carried out by PB as needed. It may be volatilized. The heating conditions for PB are appropriately selected depending on the composition of the second radiation-sensitive composition, but are usually 10 to 200 seconds at 30 to 200 ° C. and 15 to 120 seconds at 50 to 150 ° C. It is more preferable that it is 30 to 100 seconds at 60 to 120 ° C.

(I) Second radiation-sensitive composition The second radiation-sensitive composition is the radiation-sensitive composition of the present invention described later. The polymer (a), the radiation sensitive acid generator (b), the solvent (c) and the like contained in the second radiation sensitive composition will also be described later.

1-3-2. exposure:
As shown in FIG. 8, the radiation that has passed through the mask 4 having a predetermined pattern (arrow L in FIG. 8) is used to expose the second resist layer 32 formed in the space 22b of the first resist pattern 22. As a result, an alkali developing portion 35 as shown in FIG. 6 is formed. In this exposure, the position where the radiation is exposed is shifted by a half period (the width of the line portion of the first or second resist pattern is two times) from the position where the first resist pattern is formed. By doing so, the unexposed portion (line portion) of the second resist layer 32 is positioned in the middle of the two adjacent line portions 22 a of the first resist pattern 22, and the line portion 22 a of the first resist pattern 22. And a resist pattern (1L1S) in which all the line portions 42a of the second resist pattern 42 are alternately arranged at equal intervals can be obtained. At this time, radiation may optionally be passed through the immersion exposure liquid 3 such as water or a fluorine-based inert liquid.

  In addition, about exposure conditions etc., the description similar to the exposure conditions mentioned above by process (1) can be performed.

1-3-3. Formation of second resist pattern:
Next, as shown in FIG. 7, a line portion 42 a of the second resist pattern 42 is formed in the space portion 34 of the first resist pattern 22 by development.

  In addition, about the image development method, the description similar to the image development method mentioned above at process (1) can be performed. However, the organic solvent that can be added to the developer excludes alcohols, ethers, and hydrocarbons from the specific examples of the organic solvent.

  Thus, by performing steps (1) to (3), the line portions 22a of the first resist pattern 22 and the line portions 42a of the second resist pattern 42 are alternately arranged on the substrate 1 at equal intervals. Thus, a resist pattern of 1L1S (line and space is 1: 1) can be formed.

  As another embodiment of the resist pattern forming method of the present invention, for example, as shown in FIG. 9, a first resist pattern 22 of 1L1S is formed by the step (1), and this first resist is formed. In the space 22b of the pattern 22, a resist pattern in which the second resist pattern 42 of 1L1S is formed so as to be orthogonal to the first resist pattern 22 by the step (3) can be cited. In such a resist pattern, a grid-like resist pattern (contact hole pattern 15) partitioned by the line portion 22a of the first resist pattern 22 and the line portion 42a of the second resist pattern can be formed. .

  Furthermore, as another embodiment of the resist pattern forming method of the present invention, for example, as shown in FIGS. 10 and 11, a first resist pattern 22 of 1L1S is formed by the step (1). The resist pattern formed so that the 2nd resist pattern 42 of 1L1S may be orthogonally crossed with the 1st resist pattern 22 by process (3) so that the one resist pattern 22 may be covered. Even with such a resist pattern, a grid-like resist pattern (contact hole pattern 15) partitioned by the line portion 22a of the first resist pattern 22 and the line portion 42a of the second resist pattern can be formed. .

  As the resist pattern forming method of the present invention, an embodiment in which a contact hole pattern is formed as in the above-described two embodiments is also preferable.

2. Radiation sensitive composition:
In the radiation-sensitive composition, an acid labile group contained in the polymer existing in the composition is dissociated (eliminated) by the action of an acid generated from the radiation-sensitive acid generator by exposure to generate a carboxyl group. As a result, the solubility of the exposed portion in the alkaline developer is increased, and the resist pattern can be formed by being dissolved and removed by the alkaline developer. Hereinafter, the second radiation-sensitive composition used for forming the second resist layer (the radiation-sensitive composition of the present invention) and the first radiation-sensitive composition used for forming the first resist layer. The composition will be described in order.

  In addition, the “acid labile group” in the present specification is sometimes called an “acid dissociable group” and refers to a group dissociated by an acid. A polymer that is insoluble or hardly soluble in an alkali having an acid labile group is dissociated into a carboxyl group by the action of an acid, and is easily soluble in an alkali.

2-1. Second Radiation Sensitive Composition The second radiation sensitive composition comprises a polymer (a) having a lactone structure or a cyclic carbonate structure (hereinafter referred to as “polymer (a)”), and radiation sensitivity. It contains an acid generator (b) (hereinafter referred to as “acid generator (b)”) and a solvent (c).

(1) Polymer (a)
By containing the polymer (a), the second radiation-sensitive composition can form a second resist layer that is easily soluble in an alkali developer by the action of an acid.

(I) Repeating unit (a2)
The polymer (a) includes at least one repeating unit selected from the group consisting of the following general formulas (1-1) to (1-7) (hereinafter referred to as “repeating unit (a2)”).

In the general formulas (1-1) to (1-7), R ¹ represents a hydrogen atom, a methyl group, or a trifluoromethyl group. In the general formula (1-1), R ² represents a hydrogen atom or a substituted or unsubstituted alkyl group having 1 to 4 carbon atoms, and l represents an integer of 1 to 3. In the general formulas (1-4) and (1-5), R ³ represents a hydrogen atom or a methoxy group. In the general formulas (1-2) and (1-3), A represents a single bond or a methylene group, and m represents 0 or 1. In the general formulas (1-3) and (1-5), B represents an oxygen atom or a methylene group. In the general formula (1-7), Rc1 represents a single bond or a divalent linking group. Rcc represents a monovalent organic group having a cyclic carbonate structure.

Preferable examples of the monomer which gives the repeating unit (a2) include (meth) acrylic acid-3,5-dioxane-4-one-methyl ester, (meth) acrylic acid-5-oxo-4-oxa-tricyclo [5.2.1.0 ^3,8 ] dec-2-yl ester, (meth) acrylic acid-6-oxo-7-oxa-bicyclo [3.2.1] oct-2-yl ester, (meth ) Acrylic acid-7-oxo-8-oxa-bicyclo [3.3.1] non-2-yl ester, (meth) acrylic acid-2-oxotetrahydropyran-4-yl ester, (meth) acrylic acid- 4-methyl-2-oxotetrahydropyran-4-yl ester, (meth) acrylic acid-4-ethyl-2-oxotetrahydropyran-4-yl ester, (meth) acrylic acid-4-propyl- - oxo tetrahydropyran-4-yl ester, (meth) acrylic acid-7-oxo-8-oxa - tricyclo [3.3.1.1 ^{3, 9]} dec-2-yl ester, 9-oxo-8- There are oxa-bicyclo [4.3.0] non-2-yl ester, 5-oxo-4-oxa-tricyclo [4.3.1.1 ^3,8 ] dec-2-yl ester, and the like.

  In addition, the polymer (a) may contain only 1 type of repeating units (a2), and may contain 2 or more types.

(Ii) Repeating unit (a1)
The polymer (a) preferably further contains a repeating unit represented by the following general formula (2) (hereinafter referred to as “repeating unit (a1)”).

In General Formula (2), R ¹ represents a hydrogen atom, a methyl group, or a trifluoromethyl group, and R ^{4 s} are independently of each other a linear or branched alkyl group having 1 to 4 carbon atoms, or A monovalent alicyclic hydrocarbon group having 4 to 20 carbon atoms, or a divalent alicyclic hydrocarbon having 4 to 20 carbon atoms formed by bonding any two R ⁴ to each other The remaining R ⁴ represents a linear or branched alkyl group having 1 to 4 carbon atoms, or a monovalent alicyclic hydrocarbon group having 4 to 20 carbon atoms or a derivative thereof.

Among the groups represented by R ⁴ in the general formula (1), examples of the linear or branched alkyl group having 1 to 4 carbon atoms include a methyl group, an ethyl group, an n-propyl group, i- Examples include propyl group, n-butyl group, 2-methylpropyl group, 1-methylpropyl group, t-butyl group and the like.

  Examples of the monovalent alicyclic hydrocarbon group having 4 to 20 carbon atoms include cyclohexane such as norbornane, tricyclodecane, tetracyclododecane, adamantane, cyclobutane, cyclopentane, cyclohexane, cycloheptane, and cyclooctane. Groups composed of alicyclic rings derived from alkanes and the like; groups composed of these alicyclic rings are, for example, methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, 2- Examples thereof include a group substituted with a linear, branched or cyclic alkyl group having 1 to 4 carbon atoms such as a methylpropyl group, a 1-methylpropyl group and a t-butyl group.

Furthermore, examples of the divalent alicyclic hydrocarbon group having 4 to 20 carbon atoms formed by bonding any two R ⁴ to each other or derivatives thereof include, for example, norbornane, tricyclodecane, tetracyclododecane, Groups composed of alicyclic rings derived from adamantane, cyclopentane, cyclohexane, etc .; groups obtained by substituting these alicyclic rings with the alkyl group, and the like.

In the general formula (2), preferred examples of the group represented by —C (R ⁴ ) ₃ include t-butyl group, 1-n- (1-ethyl-1-methyl) propyl group, 1-n—. (1,1-dimethyl) propyl group, 1-n- (1,1-dimethyl) butyl group, 1-n- (1,1-dimethyl) pentyl group, 1- (1,1-diethyl) propyl group, Groups having no alicyclic ring such as 1-n- (1,1-diethyl) butyl group and 1-n- (1,1-diethyl) pentyl group; 1- (1-methyl) cyclopentyl group, 1 -(1-ethyl) cyclopentyl group, 1- (1-n-propyl) cyclopentyl group, 1- (1-i-propyl) cyclopentyl group, 1- (1-methyl) cyclohexyl group, 1- (1-ethyl) Cyclohexyl group, 1- (1-n-propyl) cyclohexyl group, 1- (1-i- (Lopyl) cyclohexyl group, 1- (1-methyl-1- (2-norbornyl)) ethyl group, 1- (1-methyl-1- (2-tetracyclodecanyl)) ethyl group, 1- (1-methyl -1- (1-adamantyl)) ethyl group, 2- (2-methyl) norbornyl group, 2- (2-ethyl) norbornyl group, 2- (2-n-propyl) norbornyl group, 2- (2-i -Propyl) norbornyl group, 2- (2-methyl) tetracyclododecanyl group, 2- (2-ethyl) tetracyclododecanyl group, 2- (2-n-propyl) tetracyclododecanyl group, 2- ( 2-i-propyl) tetracyclododecanyl group, 2-methyl-2-adamantyl, 2-ethyl-2-adamantyl, groups having an alicyclic ring such as 2-propyl-2-adamantyl group; these alicyclics A group having a ring For example, straight chain having 1 to 10 carbon atoms such as methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, 2-methylpropyl group, 1-methylpropyl group, t-butyl group Alternatively, there are groups substituted with a cyclic alkyl group having 4 to 20 carbon atoms such as a branched alkyl group, a cyclopentyl group, a cyclohexyl group, and a cyclooctyl group.

Preferable examples of the monomer giving the repeating unit (a1) include (meth) acrylic acid 2-methyladamantyl-2-yl ester, (meth) acrylic acid 2-methyl-3-hydroxyadamantyl-2-yl ester, (Meth) acrylic acid 2-ethyladamantyl-2-yl ester, (meth) acrylic acid 2-ethyl-3-hydroxyadamantyl-2-yl ester, (meth) acrylic acid 2-n-propyladamantyl-2-yl ester (Meth) acrylic acid 2-isopropyladamantyl-2-yl ester, (meth) acrylic acid-2-methylbicyclo [2.2.1] hept-2-yl ester, (meth) acrylic acid-2-ethylbicyclo ester [2.2.1] Hept-2-yl ester, (meth) acrylic acid-8-methyltricyclo [5.2.1. ^2,6] decan-8-yl ester, (meth) ethyl-8-acrylic acid tricyclo [5.2.1.0 ^2,6] decan-8-yl ester, (meth) acrylic acid-methyl Tetracyclo [6.2.13,6.0 ^2,7 ] dodecan-4-yl ester, (meth) acrylic acid-4-ethyltetracyclo [6.2.1.1 ^3,6 . 0 ^2,7 ] dodecan-4-yl ester, (meth) acrylic acid 1- (bicyclo [2.2.1] hept-2-yl) -1-methylethyl ester, (meth) acrylic acid 1- (tricyclo [5.2.1.0 ^2,6 ] decan-8-yl) -1-methylethyl ester, (meth) acrylic acid 1- (tetracyclo [6.2.1.1 ^3,6.0 0.0 ^2,7 ] Dodecan-4-yl) -1-methylethyl ester, (meth) acrylic acid 1- (adamantan-1-yl) -1-methylethyl ester, (meth) acrylic acid 1- (3-hydroxyadamantane-1- Yl) -1-methylethyl ester, (meth) acrylic acid 1,1-dicyclohexyl ethyl ester, (meth) acrylic acid 1,1-di (bicyclo [2.2.1] hept-2-yl) ethyl ester (Meth) acrylic acid 1,1-di (tricyclo [5.2.1.0 ^2,6] decan-8-yl) ethyl ester, (meth) acrylic acid 1,1-di (tetracyclo [6.2. 1.1 ^3,6 .0 ^2,7] dodecane-4-yl) ethyl ester, (meth) acrylic acid 1,1-di (adamantan-1-yl) ethyl ester, (meth) acrylic acid 1-methyl - 1-cyclopentyl ester, (meth) acrylic acid 1-ethyl-1-cyclopentyl ester, (meth) acrylic acid 1-methyl-1-cyclohexyl ester, (meth) acrylic acid 1-ethyl-1-cyclohexyl ester, and the like. In the present specification, “(meth) acrylic acid” refers to both acrylic acid and methacrylic acid.

  Among these, (meth) acrylic acid 2-methyladamantyl-2-yl ester, (meth) acrylic acid 2-ethyladamantyl-2-yl ester, (meth) acrylic acid-2-methylbicyclo [2.2.1]. ] Hept-2-yl ester, (meth) acrylic acid-2-ethylbicyclo [2.2.1] hept-2-yl ester, (meth) acrylic acid 1- (bicyclo [2.2.1] hept- 2-yl) -1-methylethyl ester, (meth) acrylic acid 1- (adamantan-1-yl) -1-methylethyl ester, (meth) acrylic acid 1-methyl-1-cyclopentyl ester, (meth) acrylic Acid 1-ethyl-1-cyclopentyl ester, (meth) acrylic acid 1-methyl-1-cyclohexyl ester, (meth) acrylic acid 1-ethyl-1 Cyclohexyl ester are particularly preferred.

  In addition, the polymer (a) may contain only 1 type of repeating units (a1), and may contain 2 or more types.

  The polymer (a) may contain one or more repeating units other than the repeating unit (a1) and the repeating unit (a2).

(Ratio of each repeating unit contained in polymer (a))
The proportion of the repeating unit (a1) contained in the polymer (a) is preferably 10 to 90 mol%, preferably 10 to 80 mol%, based on 100 mol% of the total repeating units contained in the polymer (a). More preferred is 20 to 70 mol%. If the ratio of the repeating unit (a1) is less than 10 mol%, the resolution of the alkali developing portion may be deteriorated. On the other hand, if it exceeds 90 mol%, the developability of the alkali developing portion may be deteriorated.

  The ratio of the repeating unit (a2) contained in the polymer (a) is preferably 5 to 70 mol%, and preferably 5 to 65 mol% with respect to 100 mol% of the total repeating units contained in the polymer (a). It is more preferable, and it is still more preferable that it is 10-60 mol%. If the ratio of the repeating unit (a2) is 5 mol% or less, the developability as a resist and the process margin may be reduced.

(Method for preparing polymer (a))
The polymer (a) is, for example, a polymerizable unsaturated monomer that gives each repeating unit described above, using a radical polymerization initiator such as a hydroperoxide, a dialkyl peroxide, a diacyl peroxide, or an azo compound. If necessary, it can be prepared by polymerization in an appropriate solvent in the presence of a chain transfer agent.

  Examples of the solvent used for polymerization include alkanes such as n-pentane, n-hexane, n-heptane, n-octane, n-nonane, n-decane; cyclohexane, cycloheptane, cyclooctane, decalin, norbornane. Cycloalkanes such as benzene, toluene, xylene, ethylbenzene, cumene and other aromatic hydrocarbons; chlorobutane, bromohexane, dichloroethane, hexamethylene dibromide, chlorobenzene and other halogenated hydrocarbons; ethyl acetate, acetic acid n- Saturated carboxylic acid esters such as butyl, i-butyl acetate and methyl propionate; ketones such as acetone, 2-butanone, 4-methyl-2-pentanone and 2-heptanone; tetrahydrofuran, dimethoxyethane, diethoxyethane and the like There are ethers. In addition, these solvents may be used individually by 1 type, and 2 or more types may be mixed and used for them.

  As polymerization conditions, the reaction temperature is usually 40 to 150 ° C, preferably 50 to 120 ° C. Moreover, reaction time is 1 to 48 hours normally, Preferably it is 1 to 24 hours.

(Physical property value of polymer (a))
The weight average molecular weight in terms of polystyrene (hereinafter referred to as “Mw”) by gel permeation chromatography (GPC) of the polymer (a) is not particularly limited, but is preferably 1,000 to 100,000. More preferably, it is 1,000-30,000, More preferably, it is 1,000-20,000. If the Mw is less than 1,000, the heat resistance of the first resist layer may be reduced. On the other hand, if it exceeds 100,000, the developability of the alkali developing portion may be lowered.

  In addition, the ratio (Mw / Mn) between the Mw of the polymer (a) and the number average molecular weight (hereinafter referred to as “Mn”) in terms of polystyrene by gel permeation chromatography (GPC) of each polymer is usually 1-5, preferably 1-3.

  In addition, the polymer (a) may contain a low molecular weight component derived from a monomer used for preparation. The content of the low molecular weight component is preferably 0.1% by mass or less, more preferably 0.07% by mass or less, based on 100% by mass (in terms of solid content) of the polymer (a). Preferably it is 0.05 mass% or less. When the content is 0.1% by mass or less, it is possible to reduce the amount of the eluate in the immersion exposure liquid such as water that has been in contact with the immersion exposure. In addition, foreign matters are less likely to occur in the resist during resist storage, and coating unevenness is less likely to occur during resist application, so that the occurrence of defects during resist pattern formation can be sufficiently suppressed.

  The “low molecular weight component” means a component having an Mw of 500 or less, and specifically includes a monomer, a dimer, a trimer, and an oligomer. The low molecular weight component can be removed by, for example, chemical purification methods such as washing with water and liquid-liquid extraction, or a combination of these chemical purification methods and physical purification methods such as ultrafiltration and centrifugation. The analysis can be performed by high performance liquid chromatography (HPLC).

  Furthermore, it is preferable that each polymer has few impurities such as halogen and metal. This is because the sensitivity, resolution, process stability, pattern shape and the like of the first resist layer to be formed can be further improved by reducing the impurities.

  Examples of the purification method of the polymer (a) include chemical purification methods such as washing with water and liquid-liquid extraction, and combinations of these chemical purification methods with physical purification methods such as ultrafiltration and centrifugation. is there.

(2) Acid generator (b)
The acid generator (b) refers to an agent that generates an acid upon exposure. When the second radiation-sensitive composition contains the acid generator (b), an acid-dissociable group, specifically a repeating unit (a1) present in the polymer by the action of an acid generated by exposure. Dissociate the acid dissociable group possessed by (eliminate the protective group), and as a result, the alkali developing part becomes readily soluble in the alkali developing solution, and a resist pattern can be formed. The acid generator (b) preferably contains a compound represented by the following general formula (9) (hereinafter referred to as “acid generator (1)”).

(I) Acid generator (1)
The acid generator (1) is a compound represented by the general formula (9).

In the general formula (9), R ¹⁴ is a hydrogen atom, a fluorine atom, a hydroxyl group, a linear or branched alkyl group having 1 to 10 carbon atoms, or a linear or branched alkoxyl group having 1 to 10 carbon atoms. Or a linear or branched alkoxycarbonyl group having 2 to 11 carbon atoms. R ¹⁵ is a linear or branched alkyl group having 1 to 10 carbon atoms, a linear or branched alkoxyl group having 1 to 10 carbon atoms, or a linear or branched group having 1 to 10 carbon atoms. Or a cyclic alkanesulfonyl group. Further, R ¹⁶ independently represents a linear or branched alkyl group having 1 to 10 carbon atoms, a phenyl group, or a naphthyl group, or two R ¹⁶ are bonded to each other. A divalent group having 2 to 10 carbon atoms containing a sulfur cation. However, the phenyl group, naphthyl group, and divalent group may have a substituent. k represents an integer of 0 to 2, and r represents an integer of 0 to 10 (preferably an integer of 0 to 2). X ⁻ represents an anion represented by general formulas (10-1) to (10-4).

In General Formulas (10-1) and (10-2), R ¹⁷ represents a fluorine atom or an optionally substituted hydrocarbon group having 1 to 12 carbon atoms. In general formula (10-1), q represents an integer of 1 to 10. In the general formulas (10-3) and (10-4), R ¹⁸ independently represents a linear or branched alkyl group having 1 to 10 carbon atoms substituted with a fluorine atom, or A divalent organic group having 2 to 10 carbon atoms and substituted with a fluorine atom, which is formed by bonding two R ¹⁸ to each other. However, the divalent organic group may have a substituent other than a fluorine atom.

  In addition, the acid generator (b) may contain the said acid generator (1) individually by 1 type, and may contain 2 or more types.

  The acid generator (b) may contain a radiation-sensitive acid generator other than the acid generator (1).

  The amount of the acid generator (b) used is usually 0.1 to 20 parts by mass with respect to 100 parts by mass of the polymer (a), preferably from the viewpoint of ensuring sensitivity and developability as a resist. 0.5 to 10 parts by mass. There exists a tendency for a sensitivity and developability to fall that the usage-amount is less than 0.1 mass part. On the other hand, if it exceeds 20 parts by mass, the transparency to radiation is lowered, and it tends to be difficult to obtain a rectangular resist pattern.

(3) Solvent (c)
Examples of the solvent (c) include 2-butanone, 2-pentanone, 3-methyl-2-butanone, 2-hexanone, 4-methyl-2-pentanone, 3-methyl-2-pentanone, 3,3-dimethyl. Linear or branched ketones such as 2-butanone, 2-heptanone, 2-octanone; cyclopentanone, 3-methylcyclopentanone, cyclohexanone, 2-methylcyclohexanone, 2,6-dimethylcyclohexanone, isophorone Cyclic ketones such as: propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, propylene glycol mono-n-propyl ether acetate, propylene glycol mono-i-propyl ether acetate, propylene glycol mono-n-butyl ether Propylene glycol monoalkyl ether acetates such as cetate, propylene glycol mono-i-butyl ether acetate, propylene glycol mono-sec-butyl ether acetate, propylene glycol mono-t-butyl ether acetate; methyl 2-hydroxypropionate, 2-hydroxypropionic acid Ethyl, 2-hydroxypropionate n-propyl, 2-hydroxypropionate i-propyl, 2-hydroxypropionate n-butyl, 2-hydroxypropionate i-butyl, 2-hydroxypropionate sec-butyl, 2-hydroxy Alkyl 2-hydroxypropionates such as t-butyl propionate; methyl 3-methoxypropionate, ethyl 3-methoxypropionate, 3-ethoxypropionate Methyl phosphate, other 3-alkoxy propionic acid alkyl such as ethyl 3-ethoxypropionate,

  n-propyl alcohol, i-propyl alcohol, n-butyl alcohol, t-butyl alcohol, cyclohexanol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol mono-n-propyl ether, ethylene glycol mono-n-butyl ether , Diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol di-n-propyl ether, diethylene glycol di-n-butyl ether, ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, ethylene glycol mono-n-propyl ether acetate, propylene glycol monomethyl ether , Propylene glycol monoethyl Ether, propylene glycol mono-n-propyl ether, toluene, xylene, ethyl 2-hydroxy-2-methylpropionate, ethyl ethoxyacetate, ethyl hydroxyacetate, methyl 2-hydroxy-3-methylbutyrate, 3-methoxybutyl acetate, 3-methyl-3-methoxybutyl acetate, 3-methyl-3-methoxybutyl propionate, 3-methyl-3-methoxybutyl butyrate, ethyl acetate, n-propyl acetate, n-butyl acetate, methyl acetoacetate, Ethyl acetoacetate, methyl pyruvate, ethyl pyruvate, N-methylpyrrolidone, N, N-dimethylformamide, N, N-dimethylacetamide, benzyl ethyl ether, di-n-hexyl ether, diethylene glycol monomethyl ether, diethylene glycol Monoethyl ether, caproic acid, caprylic acid, 1-octanol, 1-nonanol, benzyl alcohol, benzyl acetate, ethyl benzoate, diethyl oxalate, diethyl maleate, .gamma.-butyrolactone, ethylene carbonate, propylene carbonate and the like.

  Among these, linear or branched ketones, cyclic ketones, propylene glycol monoalkyl ether acetates, alkyl 2-hydroxypropionate, alkyl 3-alkoxypropionate, γ-butyrolactone and the like are preferable.

  The 2nd radiation sensitive composition may contain the solvent (c) individually by 1 type, and may contain 2 or more types.

  The amount of the solvent (c) used is such that the total solid concentration of the second radiation-sensitive composition is usually 1 to 50% by mass, preferably 1 to 25% by mass.

(4) Additive The second radiation-sensitive composition may contain various additives such as an acid diffusion controller, an alicyclic additive, a surfactant, and a sensitizer as necessary. .

(I) Acid Diffusion Control Agent The acid diffusion control agent controls the diffusion phenomenon in the second resist layer of the acid generated from the acid generator (b) by exposure and suppresses an undesirable chemical reaction in a non-exposed region. It is a component having By containing such an acid diffusion controller, the storage stability of the second radiation-sensitive composition is improved. In addition, the resolution as a resist is further improved, and it is possible to suppress changes in the line width of the resist pattern due to fluctuations in the holding time (PED) from exposure to post-exposure heat treatment, and an extremely excellent process stability. A thing is obtained.

  Examples of the acid diffusion controller include an amine compound, an amide group-containing compound, a urea compound, and a nitrogen-containing heterocyclic compound.

(Amine compound)
Preferred examples of the amine compound include mono (cyclo) alkylamines, di (cyclo) alkylamines, tri (cyclo) alkylamines, aniline or derivatives thereof, ethylenediamine, N, N, N ′, N′-tetra Methylethylenediamine, tetramethylenediamine, hexamethylenediamine, 4,4′-diaminodiphenylmethane, 4,4′-diaminodiphenyl ether, 4,4′-diaminobenzophenone, 4,4′-diaminodiphenylamine, 2,2-bis (4 -Aminophenyl) propane, 2- (3-aminophenyl) -2- (4-aminophenyl) propane, 2- (4-aminophenyl) -2- (3-hydroxyphenyl) propane, 2- (4-amino) Phenyl) -2- (4-hydroxyphenyl) propane, 1,4-bis (1- (4 Aminophenyl) -1-methylethyl) benzene, 1,3-bis (1- (4-aminophenyl) -1-methylethyl) benzene, bis (2-dimethylaminoethyl) ether, bis (2-diethylaminoethyl) Ether, 1- (2-hydroxyethyl) -2-imidazolidinone, 2-quinoxalinol, N, N, N ′, N′-tetrakis (2-hydroxypropyl) ethylenediamine, N, N, N ′, N '', N ''-pentamethyldiethylenetriamine and the like.

(Amido group-containing compound)
Preferable examples of the amide group-containing compound include Nt-butoxycarbonyl group-containing amino compound, formamide, N-methylformamide, N, N-dimethylformamide, acetamide, N-methylacetamide, N, N-dimethylacetamide. , Propionamide, benzamide, pyrrolidone, N-methylpyrrolidone, N-acetyl-1-adamantylamine, tris (2-hydroxyethyl) isocyanurate, and the like.

(Urea compound)
Preferred examples of urea compounds include urea, methylurea, 1,1-dimethylurea, 1,3-dimethylurea, 1,1,3,3-tetramethylurea, 1,3-diphenylurea, tri-n-butyl. There is thiourea.

(Nitrogen-containing heterocyclic compounds)
Preferable examples of the nitrogen-containing heterocyclic compound include imidazoles, pyridines, piperazines, pyrazine, pyrazole, pyridazine, quinosaline, purine, pyrrolidine, piperidine, piperidine ethanol, 3-piperidino-1,2-propanediol, Morpholine, 4-methylmorpholine, 1- (4-morpholinyl) ethanol, 4-acetylmorpholine, 3- (N-morpholino) -1,2-propanediol, 1,4-dimethylpiperazine, 1,4-diazabicyclo [2 2.2.2] Octane and the like.

  Further, as the acid diffusion control agent, in addition to the above-described acid diffusion control agent, a photodegradable base that is exposed to light and generates a base can be used.

(Photodegradable base)
As an example of the photodegradable base, there is an onium salt compound that is decomposed by exposure and loses acid diffusion controllability. Specific examples of such an onium salt compound include a sulfonium salt compound represented by the general formula (11) and an iodonium salt compound represented by the general formula (12).

R < ¹⁹ > -R < ²¹ > in General formula (11) and R < ²² > -R < ²³ > in General formula (12) show a hydrogen atom, an alkyl group, an alkoxyl group, a hydroxyl group, or a halogen atom mutually independently. In general formulas (11) and (12), Z ⁻ represents OH ⁻ , R ²⁴ —COO ⁻ , R ²⁴ —SO ₃ ^— (wherein R ²⁴ represents a substituted or unsubstituted alkyl group, aryl group, An anion represented by an alicyclic hydrocarbon group or an alkaryl group).

  In addition, these acid diffusion control agents may be used individually by 1 type, and 2 or more types may be mixed and used for them.

  The content of the acid diffusion controller is preferably 0.001 to 15 parts by mass, more preferably 0.01 to 10 parts by mass with respect to 100 parts by mass of the polymer (a), and 0.05 More preferably, it is -5 mass parts. If the content is more than 15 parts by mass, the sensitivity as a resist may decrease. On the other hand, if it is less than 0.001 part by mass, the pattern shape and dimensional fidelity as a resist may be lowered depending on the process conditions.

(Ii) Alicyclic additive The alicyclic additive is a component that exhibits the action of further improving dry etching resistance, pattern shape, adhesion to the substrate, and the like.

Examples of the alicyclic additive include 1-adamantanecarboxylic acid, 2-adamantanone, 1-adamantanecarboxylic acid t-butyl, 1-adamantanecarboxylic acid t-butoxycarbonylmethyl, 1-adamantanecarboxylic acid α-butyrolactone ester. 1,3-adamantane dicarboxylic acid di-t-butyl, 1-adamantane acetate t-butyl, 1-adamantane acetate t-butoxycarbonylmethyl, 1,3-adamantane diacetate di-t-butyl, 2,5-dimethyl Adamantane derivatives such as -2,5-di (adamantylcarbonyloxy) hexane; t-butyl deoxycholate, t-butoxycarbonylmethyl deoxycholic acid, 2-ethoxyethyl deoxycholic acid, 2-cyclohexyloxyethyl deoxycholic acid , Deoxycholic acid Deoxycholic acid esters such as oxocyclohexyl, deoxycholic acid tetrahydropyranyl, deoxycholic acid mevalonolactone ester; lithocholic acid t-butyl, lithocholic acid t-butoxycarbonylmethyl, lithocholic acid 2-ethoxyethyl, lithocholic acid 2 -Lithocholic acid esters such as cyclohexyloxyethyl, lithocholic acid 3-oxocyclohexyl, lithocholic acid tetrahydropyranyl, lithocholic acid mevalonolactone ester; dimethyl adipate, diethyl adipate, dipropyl adipate, di-n-butyl adipate, Alkylcarboxylic esters such as di-t-butyl adipate and 3- (2-hydroxy-2,2-bis (trifluoromethyl) ethyl) tetracyclo [6.2.1.1 ^3,6 . 0 ^2,7 ] dodecane and the like. In addition, these alicyclic additives may be used individually by 1 type, and 2 or more types may be mixed and used for them.

(Iii) Surfactant A surfactant is a component that exhibits an effect of improving coatability, striation, developability, and the like.

  Examples of the surfactant include polyoxyethylene lauryl ether, polyoxyethylene stearyl ether, polyoxyethylene oleyl ether, polyoxyethylene n-octylphenyl ether, polyoxyethylene n-nonylphenyl ether, polyethylene glycol dilaurate, polyethylene glycol In addition to nonionic surfactants such as distearate, KP341 (manufactured by Shin-Etsu Chemical Co., Ltd.), Polyflow No. 75, no. 95 (above, manufactured by Kyoeisha Chemical Co., Ltd.), F-top EF301, EF303, EF352 (above, manufactured by Tochem Products), Megafax F171, F173 (above, manufactured by Dainippon Ink and Chemicals), Florard FC430, FC431 (above, manufactured by Sumitomo 3M), Asahi Guard AG710, Surflon S-382, SC-101, SC-102, SC-103, SC-104, SC-105, SC-106 ( As mentioned above, manufactured by Asahi Glass Co., Ltd.). In addition, these surfactants may be used individually by 1 type, and 2 or more types may be mixed and used for them.

(Iv) Sensitizer A sensitizer absorbs radiation energy and transmits the energy to the acid generator (b), thereby increasing the amount of acid produced. It has the effect of improving the apparent sensitivity of the radiation-sensitive composition.

  Examples of the sensitizer include carbazoles, acetophenones, benzophenones, naphthalenes, phenols, biacetyl, eosin, rose bengal, pyrenes, anthracenes, phenothiazines, and the like. In addition, these sensitizers may be used individually by 1 type, and 2 or more types may be mixed and used for them.

(V) Other Additives The first radiation-sensitive composition may contain additives other than the additives described above (hereinafter referred to as “other additives”). Other additives include alkali-soluble resins, low-molecular alkali-solubility control agents having acid-dissociable protecting groups, antihalation agents, storage stabilizers, antifoaming agents, and the like. In addition, by including a dye or a pigment, the latent image of the exposed portion can be visualized, and the influence of halation during exposure can be reduced. Furthermore, the adhesiveness with a board | substrate can be improved by containing an adhesion assistant.

  The second radiation-sensitive composition may be prepared as a coating solution by dissolving each component in the solvent (c) and then filtering through a filter having a pore size of about 0.2 μm, and applied onto the substrate. it can.

2-2. First radiation-sensitive composition The first radiation-sensitive composition has a polymer (A) having an acid labile group and no crosslinking group (hereinafter referred to as “polymer (A)”). And a radiation-sensitive acid generator (C) (hereinafter referred to as “acid generator (C)”) and a solvent (D), and if necessary, an acid labile group And a polymer (B) having a crosslinking group (hereinafter referred to as “polymer (B)”).

(1) Polymer (A)
The 1st radiation sensitive composition can form the 1st resist layer which melt | dissolves with respect to an alkali developing solution by the effect | action of an acid by containing a polymer (A).

  The polymer (A) includes a repeating unit having an acid labile group represented by the general formula (2) (hereinafter referred to as “repeating unit (A1)”), and the general formula (1-1) to And at least one repeating unit selected from the group consisting of (1-7) (hereinafter referred to as “repeating unit (A2)”).

(I) Repeating unit (A1)
Examples of the repeating unit (A1) include repeating units having the same structure as the above-described repeating unit (a1). Among them, (meth) acrylic acid 2-methyladamantyl-2-yl ester, (meth) acrylic acid 2 -Ethyladamantyl-2-yl ester, (meth) acrylic acid-2-methylbicyclo [2.2.1] hept-2-yl ester, (meth) acrylic acid-2-ethylbicyclo [2.2.1] Hept-2-yl ester, (meth) acrylic acid 1- (bicyclo [2.2.1] hept-2-yl) -1-methylethyl ester, (meth) acrylic acid 1- (adamantan-1-yl) -1-methyl ethyl ester, (meth) acrylic acid 1-methyl-1-cyclopentyl ester, (meth) acrylic acid 1-ethyl-1-cyclopentyl ester , (Meth) acrylic acid 1-methyl-1-cyclohexyl ester, (meth) acrylic acid 1-ethyl-1-cyclohexyl ester, and the like are particularly preferable.

  In addition, a polymer (A) may contain only 1 type of repeating units (A1), and may contain 2 or more types.

(Ii) Repeating unit (A2)
Examples of the repeating unit (A2) include repeating units having the same structure as the above-described repeating unit (a2). Among them, (meth) acrylic acid-3,5-dioxane-4-one-methyl ester, (meta ) Acrylic acid-5-oxo-4-oxa-tricyclo [5.2.1.0 ^3,8 ] dec-2-yl ester, (meth) acrylic acid-6-oxo-7-oxa-bicyclo [3. 2.1] Oct-2-yl ester, (meth) acrylic acid-7-oxo-8-oxa-bicyclo [3.3.1] non-2-yl ester, (meth) acrylic acid-2-oxotetrahydro Pyran-4-yl ester, (meth) acrylic acid-4-methyl-2-oxotetrahydropyran-4-yl ester, (meth) acrylic acid-4-ethyl-2-oxotetrahydropi -4-yl ester, (meth) acrylic acid-4-propyl-2-oxotetrahydropyran-4-yl ester, (meth) acrylic acid-7-oxo-8-oxa-tricyclo [3.3.1. 1 ^3,9 ] dec-2-yl ester, 9-oxo-8-oxa-bicyclo [4.3.0] non-2-yl ester, 5-oxo-4-oxa-tricyclo [4.3.1]. ^.1,3,8 ] dec-2-yl ester and the like are particularly preferable.

  In addition, a polymer (A) may contain only 1 type of repeating units (A2), and may contain 2 or more types.

  Further, the polymer (A) may contain one or more repeating units other than the repeating unit (A1) and the repeating unit (A2) (hereinafter referred to as “other repeating units”).

  The proportion of the repeating unit (A1) contained in the polymer (A) is preferably 10 to 90 mol%, preferably 10 to 80 mol%, based on 100 mol% of the total repeating units contained in each polymer. More preferred is 20 to 70 mol%. If the ratio of the repeating unit (A1) is less than 10 mol%, the resolution of the alkali developing portion may be deteriorated. On the other hand, if it exceeds 90 mol%, the developability of the alkali developing portion may be deteriorated.

  The proportion of the repeating unit (A2) contained in the polymer (A) is preferably 5 to 70 mol%, preferably 5 to 65 mol%, based on 100 mol% of the repeating units contained in each polymer. More preferably, it is more preferably 10 to 60 mol%. If the ratio of the repeating unit (A2) is 5 mol% or less, the developability as a resist and the process margin may be reduced.

(2) Polymer (B)
The polymer (B) is represented by the following general formulas (3-1) and (3-2) in addition to at least one selected from the repeating unit (A1) and the repeating unit (A2) described in the polymer (A). It includes at least one of the repeating units represented (hereinafter referred to as “repeating unit (B3)”). The first radiation-sensitive composition contains the polymer (B), and in addition to being dissolved in an alkali developer by the action of an acid, the first resist pattern is subjected to heat or light. And inactivating the second radiation-sensitive composition.

In General Formulas (3-1) and (3-2), R ¹ represents a hydrogen atom, a methyl group, or a trifluoromethyl group. In General Formula (3-1), R ⁵ represents a methylene group, an ethylene group or a propylene group, and R ⁶ represents a group represented by Formula (4) or a group represented by Formula (5). In General Formula (3-2), R ⁷ represents a methylene group or an alkylene group having 2 to 6 carbon atoms, and R ⁸ represents a hydrogen atom, a methyl group, or an ethyl group. n represents 0 or 1.

(In said general formula (4) and (5), several R < ⁹ > shows a hydrogen atom or a C1-C10 linear or branched alkyl group mutually independently.)

  The usage-amount of the said polymer (B) is 1-80 mass parts normally with respect to 100 mass parts of said polymers (A), Preferably it is 2-50 mass parts. If the amount used is less than 1 part by mass, it may not be possible to have sufficient resistance to the second resist layer. On the other hand, if it exceeds 80 parts by mass, resolution failure may occur when the first resist pattern is formed.

(Ratio of each repeating unit contained in each polymer)
The ratio of the repeating unit (A1) contained in the polymer (B) is preferably 10 to 90 mol%, and preferably 10 to 80 mol% with respect to 100 mol% of the total repeating units contained in each polymer. More preferred is 20 to 70 mol%. If the ratio of the repeating unit (A1) is less than 10 mol%, the resolution of the alkali developing portion may be deteriorated. On the other hand, if it exceeds 90 mol%, the developability of the alkali developing portion may be deteriorated.

  The ratio of the repeating unit (A2) contained in the polymer (B) is preferably 5 to 70 mol%, and preferably 5 to 65 mol% with respect to 100 mol% in total of the repeating units contained in each polymer. It is more preferable, and it is still more preferable that it is 5-60 mol%. If the ratio of the repeating unit (A2) is 5 mol% or less, the developability as a resist and the process margin may be reduced.

  The ratio of the repeating unit (B3) contained in the polymer (B) is preferably 0.5 to 30 mol% or less with respect to 100 mol% of the total repeating units contained in the polymer (B), 25 mol % Or less is more preferable. If the ratio of the repeating unit (B3) is more than 30 mol%, the alkali developing part may be easily swollen by the alkali developer, or the solubility in the alkali developer may be reduced. If it is less than 0.5 mol%, the resistance to the second radiation-sensitive resist may be lowered.

  In addition, the 1st radiation sensitive composition may contain 1 type of each polymer, and may contain 2 or more types.

(Method for preparing each polymer)
Each polymer in the first radiation-sensitive composition conforms to the adjustment method in the second radiation-sensitive composition.

(Physical properties of each polymer)
The physical property value of each polymer in the first radiation-sensitive composition conforms to the physical property value in the second radiation-sensitive composition.

  Examples of the purification method for each polymer include chemical purification methods such as washing with water and liquid-liquid extraction, and combinations of these chemical purification methods with physical purification methods such as ultrafiltration and centrifugation.

(3) Acid generator (C)
The acid generator (C) contained in the first radiation-sensitive composition is the same as the acid generator (b) (acid generator (1)) contained in the second radiation-sensitive composition. Can be used.

  In addition, an acid generator (C) may contain the said acid generator (1) individually by 1 type, and may contain 2 or more types.

  The acid generator (C) may contain a radiation-sensitive acid generator other than the acid generator (1).

  The amount of the acid generator (C) used is usually 0.1 to 20 parts by mass with respect to 100 parts by mass of the polymer (A), preferably from the viewpoint of ensuring the sensitivity and developability as a resist. 0.5 to 10 parts by mass. There exists a tendency for a sensitivity and developability to fall that the usage-amount is less than 0.1 mass part. On the other hand, if it exceeds 20 parts by mass, the transparency to radiation is lowered, and it tends to be difficult to obtain a rectangular resist pattern.

(4) Solvent (D)
The solvent (D) contained in the first radiation-sensitive composition may be the same as the solvent (c) of the second radiation-sensitive composition.

  Among these, linear or branched ketones, cyclic ketones, propylene glycol monoalkyl ether acetates, alkyl 2-hydroxypropionate, alkyl 3-alkoxypropionate, γ-butyrolactone and the like are preferable.

  The 1st radiation sensitive composition may contain the solvent (D) individually by 1 type, and may contain 2 or more types.

  The amount of the solvent (D) used is such that the total solid concentration of the first radiation-sensitive composition is usually 1 to 50% by mass, preferably 1 to 25% by mass.

(5) Additives The first radiation-sensitive composition comprises various additives such as an acid diffusion controller, an alicyclic additive, a surfactant, a sensitizer, and other additives as necessary. May be contained. These may be the same as those contained in the second radiation-sensitive composition.

  The first radiation-sensitive composition can be prepared as a coating solution by dissolving each component in the solvent (D) and then filtering with a filter having a pore size of about 0.2 μm, and can be applied onto the substrate. it can.

  EXAMPLES Hereinafter, although this invention is demonstrated concretely based on an Example, this invention is not limited to these Examples. In the examples and comparative examples, “parts” and “%” are based on mass unless otherwise specified. Moreover, the measuring method of various physical-property values and the evaluation method of various characteristics are shown below.

  [Weight average molecular weight (Mw) and number average molecular weight (Mn)]: Tosoh GPC columns (2 G2000HXL, 1 G3000HXL, 1 G4000HXL), flow rate 1.0 mL / min, elution solvent tetrahydrofuran, column temperature 40 ° C. Under analysis conditions, the measurement was performed by gel permeation chromatography (GPC) using monodisperse polystyrene as a standard.

  [DOF margin evaluation]: In this evaluation, the following evaluation was performed on the evaluation substrate C described later, assuming a 45 nm hole / 90 nm pitch pattern. A second resist layer is formed on a substrate on which a first resist pattern is formed (45 nm line / 90 nm pitch pattern is formed on the entire surface of the wafer under the same conditions), and the second resist layer is selectively selected through a mask. In addition to using a mask having a line pattern perpendicular to the line direction of the first resist pattern, the focus value is intentionally shifted, and the second resist pattern size at each focus offset value is set to CG−. Measured using 4000. A defocus area in which the measured value is within ± 10% with respect to the target pattern size value of 45 nm is defined as a DOF margin, and it is determined that a wider area is more desirable in the lithography process. Table 2 shows the exposure amount (sensitivity) necessary for forming the second resist pattern.

[Limited resolution evaluation]: In this evaluation, in the evaluation substrate F to be described later, the ratio of line / pitch = 1/2 is fixed, the line width is swung in a fine direction, and the limit resolution is set using CG-4000. Measured. It was determined that the smaller this value, the more desirable in the lithography process. The pattern forming method at this time is as follows. On the substrate on which the first resist pattern is formed (Xnm line / (4 times X) nm pitch pattern is formed on the entire surface of the wafer under the same conditions. The value of X is arbitrary) When the second resist layer is formed, and the second resist layer is selectively exposed through the mask, the exposure is performed through the line pattern mask in a direction parallel to the line direction of the first resist pattern, and the overlay is performed. Thereafter, the pattern was formed at a ratio of line / pitch = 1/2. At this time, the exposure amount (sensitivity) necessary for forming the first resist pattern is 29 mJ / cm ² . Table 2 shows the exposure amount (sensitivity) necessary for forming the second resist pattern.

Preparation of first radiation-sensitive composition (hereinafter referred to as first resist 1) 90 parts of polymer (A-1) having the composition of the following formula (A-1) as polymer (A), polymer (B) ) 10 parts of the polymer (B-1) having the composition of the following formula (B-1) as the acid generator (C), 7.5 parts of triphenylsulfonium nonafluoro-n-butanesulfonate, the nitrogen-containing compound (E ) 0.94 parts of Nt-butoxycarbonylpyrrolidine, and (D) 2010 parts of propylene glycol monomethyl ether acetate and 861 parts of cyclohexanone were added, and the components were mixed to obtain a homogeneous solution. Then, the coating liquid (1st resist 1) which consists of a 1st radiation sensitive composition was prepared by filtering using a membrane filter with a hole diameter of 200 nm (total solid content concentration of about 5%). In addition, Mw of the polymer (A-1) was 10,000, and Mw of the polymer (B-1) was 10,000.

Example 1
Preparation of second radiation-sensitive composition (hereinafter referred to as second resist 1) As polymer (a), 100 parts of polymer (a-1) having the composition of the following formula (a-1), acid generator ( The acid generator (b-1) (triphenylsulfonium nonafluoro-n-butanesulfonate) 7.5 parts as b), the acid diffusion inhibitor (d-1) (Nt-butoxy) as the nitrogen-containing compound (d) 0.94 parts of carbonyl pyrrolidine), and (c) 2010 part of solvent (c-1) (propylene glycol monomethyl ether acetate) and 861 parts of solvent (c-2) (cyclohexanone) are added and mixed. To obtain a homogeneous solution. Then, the coating liquid (2nd resist 1) which consists of a 2nd radiation sensitive composition was prepared by filtering using a membrane filter with a hole diameter of 200 nm (total solid content concentration of about 5%). In addition, Mw of the polymer (a-1) was 10,000.

(Examples 2-5, Comparative Examples 1-2)
Each coating solution was prepared in the same manner as in Example 1 except that the formulation shown in Table 1 was used.

  The types of the acid generator, the solvent, and the acid diffusion controller omitted in Table 1 are described below.

(Acid generator)
b-2: triphenylsulfonium a, a-difluorobicyclo [2.2.1] heptane-2-ethanesulfonate (solvent)
c-3: 4-methyl-2-pentanol (acid diffusion controller)
d-2: Triphenylsulfonium salicylate

  In addition, each composition of the polymer (a) described in Table 1 below is shown by the following structural formulas (a-1) to (a-7). Moreover, the kind of acid generator (b), a solvent (c), and a nitrogen-containing compound (d) is described.

  Acid generator (b-1): triphenylsulfonium nonafluoro-n-butanesulfonate

Solvent (c-1): Propylene glycol monomethyl ether acetate Solvent (c-2): Cyclohexanone

  Acid diffusion controller (d-1): Nt-butoxycarbonylpyrrolidine

(Resist pattern formation for DOF margin evaluation)
(Example 6)
A 12-inch silicon wafer was spin-coated with a lower antireflection film (trade name “ARC66”, manufactured by Brewer Science) using a trade name “CLEAN TRACK Lithius Pro i” (manufactured by Tokyo Electron), and then PB By carrying out (205 ° C., 60 seconds), a coating film having a film thickness of 105 nm was formed. The first resist 1 (first radiation-sensitive composition) was spin-coated using a trade name “CLEAN TRACK Lithius Pro i”, PB (130 ° C., 60 seconds), and then cooled (23 ° C., 30 Second) to form a first resist layer having a thickness of 100 nm.

  Next, using an ArF immersion exposure apparatus (trade name “NSR-S610C”, manufactured by Nikon Seiki Company), exposure was performed under the optical conditions of NA: 1.3 and Dipole. PEB (125 ° C, 60 seconds) on a hot plate of the product name “CLEAN TRACK Lithius Pro i”, cooled (23 ° C., 30 seconds), and then 2.38% tetramethyl with the LD nozzle of the developing cup. Paddle development (30 seconds) was performed using an aqueous ammonium hydroxide solution as a developer, and rinsed with ultrapure water. A substrate A on which a first resist pattern of 45 nm line / 90 nm pitch pattern was formed was obtained by spin-drying by shaking off at 2000 rpm for 15 seconds.

  PEB (200 ° C., 90 seconds) was performed on the obtained first resist pattern of the evaluation substrate A on a hot plate having a trade name “CLEAN TRACK Lithius Pro i” to obtain a substrate B.

  The coating liquid (1) (second radiation-sensitive composition) prepared in Example 1 was spin-coated on the evaluation substrate B using the trade name “CLEAN TRACK Lithius Pro i”, and PB (100 ° C. , 60 seconds), and then cooled (23 ° C., 30 seconds) to form a second resist layer having a thickness of 100 nm. Next, using an ArF immersion exposure apparatus (trade name “NSR-S610C”, manufactured by Nikon Seiki Company), exposure is performed in a direction perpendicular to the first resist pattern under the optical conditions of NA: 1.3 and Dipole. did. PEB (110 ° C., 60 seconds) on a hot plate of the trade name “CLEAN TRACK Lithius Pro i”, cooled (23 ° C., 30 seconds), and then 2.38% tetramethyl with the LD nozzle of the developing cup. Paddle development (30 seconds) was performed using an aqueous ammonium hydroxide solution as a developer, and rinsed with ultrapure water to obtain an evaluation substrate C on which a second resist pattern having a 45 nm line / 90 nm pitch pattern was formed.

(Resist pattern formation for critical resolution evaluation)
A 12-inch silicon wafer was spin-coated with a lower antireflection film (trade name “ARC66”, manufactured by Brewer Science) using a trade name “CLEAN TRACK Lithius Pro i” (manufactured by Tokyo Electron), and then PB By carrying out (205 ° C., 60 seconds), a coating film having a film thickness of 105 nm was formed. The first resist 1 (first radiation-sensitive composition) was spin-coated using a trade name “CLEAN TRACK Lithius Pro i”, PB (130 ° C., 60 seconds), and then cooled (23 ° C., 30 Second) to form a first resist layer having a thickness of 70 nm.

  Next, using an ArF immersion exposure apparatus (trade name “NSR-S610C”, manufactured by Nikon Seiki Company), exposure was performed under the optical conditions of NA: 1.3 and Dipole. PEB (125 ° C, 60 seconds) on a hot plate of the product name “CLEAN TRACK Lithius Pro i”, cooled (23 ° C., 30 seconds), and then 2.38% tetramethyl with the LD nozzle of the developing cup. Paddle development (30 seconds) was performed using an aqueous ammonium hydroxide solution as a developer, and rinsed with ultrapure water. Spin drying was performed by shaking off at 2000 rpm for 15 seconds to obtain a substrate D on which a first resist pattern having various Xnm lines / (4 times X) nm pitch (the value of X was arbitrary) was formed.

  PEB (200 ° C., 90 seconds) was performed on a hot plate having a trade name “CLEAN TRACK Lithius Pro i” on the first resist pattern of the obtained evaluation substrate D to obtain a substrate E.

  The coating liquid (2) (second radiation sensitive composition) prepared in Example 1 was spin-coated on the evaluation substrate E using the trade name “CLEAN TRACK Lithius Pro i”, and PB (100 ° C. , 60 seconds), and then cooled (23 ° C., 30 seconds) to form a second resist layer having a thickness of 70 nm. Using the product name “NSR-S610C, NA: 1.3, Dipole under optical conditions, exposure was performed in the parallel direction between the spaces of the first resist pattern. Product name“ CLEAN TRACK Lithius Pro i ”hot plate After PEB (110 ° C., 60 seconds) and cooling (23 ° C., 30 seconds) above, paddle development (30% tetramethylammonium hydroxide aqueous solution as a developing solution with a LD nozzle of the developing cup (30 And rinsed with ultrapure water. An evaluation substrate F on which a second resist pattern having an Xnm line / (4 times X) nm pitch (the value of X is arbitrary) is formed between first spaces by spin drying at 2000 rpm for 15 seconds. Got.

(Examples 7 to 10, Comparative Examples 3 to 4)
Except what described in Table 2, it carried out similarly to Example 6, and obtained each board | substrate C and F for evaluation. The evaluation results of the obtained evaluation substrates C (DOF margin evaluation) and F (limit resolution evaluation) are shown together in Table 2.

  According to the resist pattern forming method using the radiation-sensitive composition of the present invention, a good DP pattern showing a sufficiently wide DOF margin and a high limit resolution can be formed.

  According to the resist pattern forming method using the radiation-sensitive composition of the present invention, it is possible to form a satisfactory DP pattern showing a sufficiently wide DOF margin and high resolution. It can be used very suitably in the field of microfabrication represented by the manufacture of integrated circuit elements.

It is sectional drawing which shows typically the state after forming the 1st resist layer on the board | substrate in the process (1) of one Embodiment of the resist pattern formation method of this invention. It is sectional drawing which shows typically the state after the 1st resist layer was exposed in the process (1) of one Embodiment of the resist pattern formation method of this invention. It is sectional drawing which shows typically the state after the 1st resist pattern was formed in the process (1) of one Embodiment of the resist pattern formation method of this invention. It is sectional drawing which shows typically the state to expose in process (i) of one Embodiment of the resist pattern formation method of this invention. It is sectional drawing which shows typically the state after the 2nd resist layer was formed on the 1st resist pattern in process (2) of one Embodiment of the resist pattern formation method of this invention. It is sectional drawing which shows typically the state after the 2nd resist layer was exposed in the process (2) of one embodiment method of the resist pattern formation method of this invention. It is sectional drawing which shows typically the state after the 2nd resist pattern was formed in the process (2) of one Embodiment of the resist pattern formation method of this invention. It is sectional drawing which shows typically the board | substrate in the state which exposes the 1st resist layer or the 2nd resist layer in process (1) and process (2) of one Embodiment of the resist pattern formation method of this invention. . It is a top view which shows typically the resist pattern formed in other embodiment of the resist pattern formation method of this invention. It is a top view which shows typically the resist pattern formed in other embodiment of the resist pattern formation method of this invention. FIG. 11 is a side view schematically showing the resist pattern shown in FIG. 10.

  E: Optical system, L: Radiation (light), 1: Substrate, 2: First resist layer, 3: Liquid for immersion exposure, 4: Mask, 5, 35: Alkali developing part, 6: Lens, 12, 22: first resist pattern, 12a, 22a: first resist pattern line portion, 12b, 22b: first resist pattern space portion, 15: contact hole pattern, 32: second resist layer, 42: 2nd resist pattern, 42a: Line part of 2nd resist pattern, 42b: Space part of 2nd resist pattern.

Claims (8)

A step (1) of forming a first resist pattern on a substrate using the first radiation-sensitive composition;
A step (2) of insolubilizing the first resist pattern with respect to the second radiation-sensitive composition;
A step (3) of forming a second resist pattern on the substrate on which the first resist pattern is formed using the second radiation-sensitive composition; A radiation-sensitive composition used as a radiation-sensitive composition of
A radiation sensitive material comprising a polymer (a), a radiation sensitive acid generator (b), and a solvent (c), wherein the polymer (a) comprises a repeating unit having a lactone structure or a cyclic carbonate structure. Composition. The polymer (a) includes at least one repeating unit (a2) selected from the group consisting of the following general formulas (1-1) to (1-7). Radiation sensitive composition.
(In the general formulas (1-1) to (1-7), R ¹ represents a hydrogen atom, a methyl group or a trifluoromethyl group. In the general formula (1-1), R ² represents hydrogen. Represents an atom or a substituted or unsubstituted alkyl group having 1 to 4 carbon atoms, and l represents an integer of 1 to ^{3. In the} general formulas (1-4) and (1-5), R ³ represents hydrogen. In the general formulas (1-2) and (1-3), A represents a single bond or a methylene group, and m represents 0 or 1. In the general formulas (1-2) and (1-3), m represents 0 or 1. ) And (1-5), B represents an oxygen atom or a methylene group, R ^c1 represents a single bond or a divalent linking group in the general formula (1-7), and R ^cc represents a cyclic carbonate structure. A monovalent organic group having   The feeling of Claim 2 whose ratio of the repeating unit (a2) contained in the said polymer (a) is 1-80 mol% with respect to a total of 100 mol% of the repeating unit contained in the said polymer (a). Radiation composition. The radiation sensitive composition of Claims 1-3 in which the said polymer (a) has a repeating unit represented by following General formula (2).
(In the general formula (2), R ¹ represents a hydrogen atom, a methyl group or a trifluoromethyl group, and R ^{4 s} are independently of each other a linear or branched alkyl group having 1 to 4 carbon atoms, Or a monovalent alicyclic hydrocarbon group having 4 to 20 carbon atoms, or a bivalent alicyclic carbon atom having 4 to 20 carbon atoms formed by bonding any two R ^{4 's} to each other. Represents a hydrogen group or a derivative thereof, and the remaining R ⁴ represents a linear or branched alkyl group having 1 to 4 carbon atoms, or a monovalent alicyclic hydrocarbon group having 4 to 20 carbon atoms or a derivative thereof. .) Forming a first resist pattern on the substrate (1);
A step (2) of insolubilizing the first resist pattern with respect to the second radiation-sensitive composition;
A step (3) of forming a second resist pattern on the substrate on which the first resist pattern is formed using the radiation-sensitive composition according to any one of claims 1 to 4. A resist pattern forming method. The first resist pattern has a line portion and a space portion,
The second resist pattern has a line portion and a space portion,
The resist pattern forming method according to claim 5, wherein the second resist pattern is formed so that the line portion of the first resist pattern and the line portion of the second resist pattern intersect each other. . The first resist pattern has a line portion and a space portion,
The second resist pattern has a line portion and a space portion,
The resist pattern forming method according to claim 5, wherein the second resist pattern is formed so that the line portion of the first resist pattern and the line portion of the second resist pattern are parallel to each other. The resist pattern forming method according to claim 5, wherein the step (2) is a step of applying heat of 100 ° C. to 250 ° C. to the first resist pattern.