JP3476359B2 - Resist material, method for preparing the same, and method for forming resist pattern - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resist material, and more specifically to a chemically amplified resist material having high resolution, high sensitivity, and excellent dry etching resistance. The present invention also relates to a method for preparing such a novel resist material, particularly a method for preparing an acid-sensitive copolymer used as a base resin. Furthermore, the present invention relates to a method for forming a resist pattern using the resist material of the present invention. The resist material according to the present invention can be advantageously used for manufacturing a semiconductor device such as a semiconductor integrated circuit because of its excellent characteristics.

[0002]

2. Description of the Related Art In recent years, integration of semiconductor integrated circuits has advanced, and LSI and VLSI have been put to practical use. Further, along with this, the minimum pattern of the integrated circuit is in the submicron region, and there is a tendency for further miniaturization. . To form a fine pattern, cover the substrate on which the thin film is formed with a resist,
It is essential to have a lithographic technique in which a latent image of a desired pattern is formed by selective exposure and then developed to form a resist pattern, dry etching is performed using this as a mask, and then the resist is removed to obtain the desired pattern. is there. Then, as an exposure light source for printing a circuit pattern used for this lithography, g-line (wavelength 4
36 nm), i-line (wavelength 365 nm) ultraviolet light is used, but with the miniaturization of patterns, far-ultraviolet light of shorter wavelength, vacuum ultraviolet light, electron beam (EB), X-ray, etc. are used as light sources. It is becoming used. In particular, recently, an excimer laser (a KrF laser having a wavelength of 248 nm and an ArF laser having a wavelength of 193 nm) has been attracting attention as an exposure light source and is expected to be effective for forming a fine pattern. In particular, a KrF laser is already used for forming a fine pattern. It is used. In this specification, when the term "radiation" is used, light from these various light sources, that is, ultraviolet light, far ultraviolet light, vacuum ultraviolet light, electron beam, X-ray,
A line, various laser beams, etc. are meant.

In order to form a submicron pattern by using exposure light in the far ultraviolet or vacuum ultraviolet region having a shorter wavelength, the resist material used has excellent transparency and excellent dry etching resistance. It is necessary to have
The present inventors have previously clarified that a chemically amplified resist containing an acrylic resin having an alicyclic hydrocarbon structure and an acid generator has such characteristics, and filed a patent application (for example, Japanese Patent Laid-Open Publication No. Hei 10 (1999) -135242). See Japanese Patent Publication No. 4-39665). In addition, Japanese Patent Laid-Open No. 9-73173 proposes the introduction of a leaving cyclic hydrocarbon group in order to enable more stable patterning. That is, in this publication, by adopting an alicyclic hydrocarbon group-containing moiety having an acid elimination structure and removing the alicyclic hydrocarbon group, it is possible to reduce the peeling of the pattern during development. Amplified resists have been proposed. Furthermore, JP-A-9-906
In JP-A 37-37, introduction of a lactone structure was also proposed. That is, in this publication, in a chemically amplified resist material containing an acid-sensitive polymer having a protective group-containing carboxyl group on the side chain of a monomer unit and an acid generator, the protective group of the acid-sensitive polymer is used. It has been proposed to introduce a lactone structure to form a fine positive pattern having a practical sensitivity and excellent adhesion.

[0004]

The chemically amplified resist material, which has been clarified by the present inventors, has many remarkable effects as described above.
A resist material having both a eliminable cyclic hydrocarbon group and a lactone structure is remarkable in that it has extremely high performance. However, such excellent resist materials still have problems to be solved. That is, in the case of this type of resist material, the characteristics thereof tend to vary from lot to lot, and it is also desirable to improve the yield and the pattern profile and the process margin.

The first object of the present invention, therefore, is to solve the problems of the prior art as described above, and to solve the problems in the resist material of the type having both a leaving cyclic hydrocarbon group and a lactone structure. Without deteriorating many characteristics derived from the structure of the material resin, that is, high resolution, high sensitivity,
Then, while maintaining excellent dry etching resistance, a chemically amplified resist material that can eliminate variations in characteristics between resin lots, and at the same time improve yield, pattern profile and process margin can be obtained. To provide.

Another object of the present invention is to provide a method for preparing such a chemically amplified resist material. Still another object of the present invention is to provide a method for forming a resist pattern using such a chemically amplified resist material. The above and other objects of the present invention will be easily understood from the following detailed description.

[0007]

As a result of earnest research to solve the above-mentioned problems, the present inventor has found that in the case of the conventional chemically amplified resist material of the above-mentioned type, the base resin constituting the same is used. The dispersity of an acid-sensitive copolymer is usually 2 to
This is a relatively large amount of about 3 and therefore tends to cause variations in resin lots and further makes it difficult to purify, and also causes a large loss due to removal of undesired resin in the refining stage, resulting in a high yield. We obtained the finding that it is a cause of loss. It was also found that it is difficult to obtain a good profile and exposure margin because the resin has a wide molecular weight distribution and includes a wide range of molecular weights. Based on these findings and discoveries, the present inventor has completed the following invention.

In one aspect, the present invention contains at least the following first and second monomer units: an alkali-soluble group protected by a protecting group having an alicyclic hydrocarbon structure, and the protecting group is an acid group. Containing a first monomer unit having a structural unit capable of leaving the copolymer to be alkali-soluble by removing with an alkali-soluble group protected by a protective group having a lactone structure, and the protective group being eliminated by an acid. And a second monomer unit having a structural unit that makes the copolymer alkali-soluble, and an acid-sensitive copolymer formed by copolymerization, and an acid generator that generates an acid upon exposure to radiation. In the chemically amplified resist material, the acid-sensitive copolymer comprises a monomer corresponding to each of the first and second monomer units. Radicals in accordance with the consumption amount of the monomer
A chemically amplified resist material is characterized by being prepared by adding it to a solution polymerization reaction system.

Further, in another aspect of the present invention, at least the following first and second monomer units: an alkali-soluble group protected by a protecting group having an alicyclic hydrocarbon structure, and The protective group contains a first monomer unit having a structural unit capable of leaving the copolymer alkali-soluble by elimination with an acid, and an alkali-soluble group protected by a protective group having a lactone structure, and the protective group is An acid-sensitive copolymer, which is formed by copolymerization of a second monomer unit having a structural unit that eliminates with an acid to make the copolymer alkali-soluble, and an acid is generated by radiation exposure. A method for preparing a chemically amplified resist material comprising an acid generator, wherein the acid-sensitive copolymer is prepared from the first and second monomer units. Is to a method for the preparation of the chemically amplified resist material characterized by comprising the step of preparing by adding the radical solution polymerization reaction system in accordance with a monomer corresponding to the record to the consumption of these monomers.

Furthermore, the invention in another of its aspects at least the following first and second monomer units:
A first monomer unit containing an alkali-soluble group protected by a protecting group having an alicyclic hydrocarbon structure and having a structural unit by which the protecting group is eliminated by an acid to make the copolymer alkali-soluble; And a second monomer unit containing an alkali-soluble group protected by a protecting group having a lactone structure and having a structural unit which makes the copolymer alkali-soluble by elimination of the protecting group from an acid. And a monomer corresponding to each of the first and second monomer units in the radical solution polymerization reaction system according to the consumption amount of the monomers. applying an acid-sensitive copolymer prepared <br/> by adding a chemically amplified resist material containing an acid generator which generates an acid upon radiation exposure on the substrate to be processed Forming a resist film, selectively exposing the resist film on the substrate to be treated to radiation capable of causing the generation of an acid from the acid generator, and developing the latent image formed in the exposing step. And a resist pattern forming method.

As will be described in detail below, the present invention is characterized by a polymerization process of an acid-sensitive copolymer used as a base resin of a chemically amplified resist material. That is, when an acid-sensitive copolymer is prepared from a monomer as its starting material, the polymerization reaction is started in a state where all the monomers are charged in a reaction vessel as in the conventional polymerization method. In this case, the heat of reaction generated makes it impossible to control the temperature in the initial stage of the reaction. Therefore, the obtained copolymer becomes a copolymer having a high degree of dispersion as described above, and the loss during purification is large, and the resist performance varies. The acid-sensitive copolymer used in the chemically amplified resist material of the present invention preferably has a molecular weight of about 4,000 to 20,000 corresponding to a dispersity of 1.7 or less, as will be described below. However, in the case of the conventional polymerization method, in order to have a molecular weight in such a range, it was essential to add a large amount of a polymerization initiator. However, the polymerization initiator does not completely consume what was charged for the reaction at the time of completion of the polymerization, so that it remains in the copolymer, resulting in variation in performance of the resulting resist material or performance fluctuation. It is a factor that causes the decline.

On the other hand, according to the present invention, the monomer is
While monitoring the polymerization process, the amount of the polymerization initiator used can be minimized by adding it according to the reaction consumption amount, and thereby, in contrast to the conventional tail-spreading molecular weight distribution. Moreover, it is possible to obtain a copolymer having a steep peak, in other words, a dispersion degree of which is narrower. Furthermore, this makes it possible to suppress loss during purification and obtain stable resist performance.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below with reference to its embodiments. In the practice of the present invention, the acid-sensitive copolymer used as the base resin of the chemically amplified resist material has at least the following first and second monomer units: alicyclic carbon as described above. A first monomer unit containing an alkali-soluble group protected by a protecting group having a hydrogen structure, a second monomer unit containing an alkali-soluble group protected by a protecting group having a lactone structure, and, if necessary, The first and second
Formed by copolymerization of a third monomer unit containing an alkali-soluble group protected by a protecting group different from the protecting group of the monomer unit of, or containing a polar group or an unprotected alkali-soluble group Is.
Such an acid-sensitive two-component or three-component copolymer may be used alone, or two or more copolymers may be mixed and used. In these acid sensitive copolymers, when an acid is generated as a result of exposure from an acid generator used in combination therewith, the first and second monomer units and, if included, the third monomer. The alkali-soluble group can be exhibited because the protecting group is eliminated from the alkali-soluble group protected by the protecting group in the unit by an acid. The alkali-soluble copolymer therefore has
It is dissolved and removed by the subsequent alkali development to obtain a desired resist pattern.

More specifically, the acid-sensitive copolymer which can be advantageously used in the practice of the present invention contains an alkali-soluble group in at least the first and second monomer units, as described above. In addition, when the third monomer unit is included for the formation of the three-component copolymer, the monomer unit may also contain a protected alkali-soluble group, and rather, However, for the third monomer unit, it may contain a polar group or an unprotected alkali-soluble group. As the alkali-soluble group, various groups generally used in the field of chemically amplified resist can be used, but preferably a carboxylic acid group, a sulfonic acid group, an amide group, an imide group, a phenol group and the like. And a carboxylic acid group is particularly preferable. Examples of polar groups include a cyano group and a hydroxyethyl group.

In the acid-sensitive copolymer of the present invention, the first
In the monomer unit, the above-mentioned alkali-soluble carboxylic acid group and the like are protected by a protective group having a specific alicyclic hydrocarbon structure. The alicyclic hydrocarbon structure of this protecting group can be an alicyclic hydrocarbon group generally used in the field of chemically amplified resists. A suitable alicyclic hydrocarbon group has, for example, the following compounds as a skeleton.

(1) Adamantane and its derivative (2) Norbornane and its derivative (3) Perhydroanthracene and its derivative (4) Perhydronaphthalene and its derivative (5) Tricyclo [5.2.1.0 ^2,6] ] Decane and its derivatives (6) Cyclohexane, methylcyclohexane, dimethylcyclohexane, bicyclohexane and its derivatives (7) Spiro [4,4] nonane and its derivatives (8) Spiro [4,5] decane and its derivatives These compounds Are each represented by the following structural formulas:

[0017]

[Chemical 15]

In the above formula, (6) is an example of bicyclohexane. Among these alicyclic hydrocarbon groups, those which can be advantageously used in the practice of the present invention are:
Those having a skeleton of adamantane and its derivatives, for example, an adamantyl group and a 2-methyladamantyl group represented by the following formula. Adamantyl group:

[0019]

[Chemical 16]

2-Methyladamantyl group:

[0021]

[Chemical 17]

Further, in this first monomer unit,
As the structure of the monomer unit itself, various structures generally used in this technical field can be adopted, but usually, (meth) acrylate-based monomer units, that is, acrylate-based and methacrylate-based monomer units, vinylphenol-based monomers Units, vinyl benzoic acid type monomer units, N-substituted maleimide type monomer units, styrene type monomer units and the like, and (meth) acrylate type monomer units are particularly preferable.

In the acid-sensitive copolymer of the present invention, it is essential that the second monomer unit contains a lactone structure as a protective group. Here, as a suitable lactone structure, the following formula (I) or (II) can be mentioned.

[0024]

[Chemical 18]

[0025]

[Chemical 19]

In the above formula, R ₁ represents a hydrogen atom or is a substituted or unsubstituted linear or branched hydrocarbon group having 1 to 4 carbon atoms, preferably a methyl group. , Ethyl groups, butyl groups, and other lower alkyl groups, and n is an integer of 1 to 4, among these lactone structures, those which can be advantageously used in the practice of the present invention are, for example, those represented by the following formula: And 3-hydroxybutyrolactone and γ-butyrolactone. 3-hydroxybutyrolactone:

[0027]

[Chemical 20]

Γ-Butyrolactone:

[0029]

[Chemical 21]

As the second monomer unit having such a lactone structure, various structures generally used in this technical field can be adopted,
Usually, like other monomer units, (meth) acrylate-based monomer units, that is, acrylate-based and methacrylate-based monomer units, vinylphenol-based monomer units, vinylbenzoic acid-based monomer units, N-substituted maleimide-based monomer units, Styrene-based monomer units are included, and (meth) acrylate-based monomer units are particularly preferable.

In the acid-sensitive copolymer of the present invention, the third monomer unit, which can be optionally incorporated, is protected by a protecting group different from the protecting groups of the first and second monomer units described above. It is desirable to include an alkali-soluble group, which may be a polar group or an alkali-soluble group. Here, the third monomer unit is not particularly limited as long as the third monomer unit has an acid elimination ability and is of a lower price, as long as the resist performance is not impaired. However, from the viewpoint of dry etching resistance, it is preferable that the protective group does not contain oxygen atoms or has a small oxygen atom content. Therefore, examples of the protecting group to be contained in the third monomer unit include a t-butyl group and a t-amyl group, and a t-butyl group is particularly preferable. Further, as other protective groups that can be advantageously introduced in the third monomer unit, for example, (1) 3-oxocyclohexyl group and (2) tetrahydropyranyl represented by the following formulas, respectively, are exemplified. Examples of the polar group or alkali-soluble group that can be used as necessary include, for example, a (3) cyano group and a (4) hydroxyethyl group represented by the following formulas, respectively. Group and (5) carboxyl group.

[0032]

[Chemical formula 22]

Although the alkali-soluble group to be contained in the third monomer unit is not particularly limited,
Preferably, as in the case of the first and second monomer units described above, a carboxylic acid group, a sulfonic acid group, an amide group, an imide group, a phenol group and the like are preferable, and a carboxylic acid group is particularly preferable. As the structure of the monomer unit itself, various structures generally used in this technical field can be adopted, but normally, like other monomer units, a (meth) acrylate-based monomer unit, that is, an acrylate-based monomer unit, It includes a methacrylate-based monomer unit, a vinylphenol-based monomer unit, a vinylbenzoic acid-based monomer unit, an N-substituted maleimide-based monomer unit, a styrene-based monomer unit, and the like, and a (meth) acrylate-based monomer unit is particularly preferable.

The acid-sensitive two-component copolymer of the present invention can preferably be represented by the following formula (III).

[0035]

[Chemical formula 23]

In the above formula, R may be the same or different and is a hydrogen atom, a halogen atom or a substituted or unsubstituted hydrocarbon group having 1 to 4 carbon atoms, preferably lower alkyl. Represents a group, R _I represents a substituted or unsubstituted hydrocarbon group having 1 to 4 carbon atoms, and Z represents an alicyclic carbon group such as those listed above together with the carbon atoms described. Represents a plurality of atoms required to complete a hydrogen structure, and LAC is represented by the above formula (I) or (II)
Represents a lactone structure represented by, and k and m
Is the number of monomer units constituting the acid-sensitive two-component copolymer, and their ratio k: m is 45 to 90:10 to 55 in terms of molar ratio.

Molecular weight (weight average molecular weight, Mw) of the acid-sensitive two-component copolymer having the structure as described above.
Is not particularly limited and can be changed in a wide range, but it is usually preferably in the range of about 4000 to 20000. The acid-sensitive two-component copolymer that can be advantageously used in the practice of the present invention is not specifically limited to those listed below, but the following copolymers can be used. Include. In addition,
K and m in the formula are the same as defined above. 2-Methyl-2-adamantyl methacrylate / mevalonic lactone methacrylate copolymer:

[0038]

[Chemical formula 24]

2-Methyl-2-adamantyl methacrylate / γ-butyrolactone-3-yl methacrylate copolymer:

[0040]

[Chemical 25]

2-Methyl-2-adamantyl methacrylate / γ-butyrolactone-2-yl methacrylate copolymer:

[0042]

[Chemical formula 26]

The acid-sensitive three-component copolymer of the present invention can be preferably represented by the following formula (IV).

[0044]

[Chemical 27]

Where R, R _I , Z and LAC
Are each as defined above, and A is any protecting group which can be removed by an acid, preferably Z and LA.
It represents a protecting group other than the C structure, more preferably a t-butyl group, a 3-oxocyclohexyl group or a tetrahydropyranyl group, and k, l and m respectively represent the acid-sensitive three-component copolymer. The number of constituent monomer units and their ratio k: 1: m, expressed as a molar ratio,
45 to 75:15 to 40:10 to 35. Note that −
The C (O) -OA group may be a polar group or an alkali-soluble group such as a cyano group, a hydroxyethyl group and a carboxyl group.

Molecular weight (weight average molecular weight, Mw) of the acid-sensitive three-component copolymer having the structure as described above.
Is not particularly limited and can be changed in a wide range, but normally, it is preferably in the range of about 4,000 to 20,000, like the acid-sensitive two-component copolymer described above. The acid-sensitive three-component copolymer that can be advantageously used in the practice of the present invention is, more specifically, not limited to those listed below, but the following copolymers can be used. Include. In the formula, t-Bu is an abbreviation for t-butyl group, and k, l and m are the same as defined above. 2-Methyl-2-adamantyl methacrylate / t-butyl methacrylate / mevalonic lactone methacrylate copolymer:

[0047]

[Chemical 28]

2-Methyl-2-adamantyl methacrylate / t-butyl methacrylate / γ-butyrolactone-3-yl methacrylate copolymer:

[0049]

[Chemical 29]

2-Methyl-2-adamantyl methacrylate / t-butyl methacrylate / 3-methyl-γ-butyrolactone-3-yl methacrylate copolymer:

[0051]

[Chemical 30]

2-Methyl-2-adamantyl methacrylate / t-butyl methacrylate / γ-butyrolactone-2-yl methacrylate copolymer:

[0053]

[Chemical 31]

The above-mentioned acid-sensitive two-component and three-component copolymers are, if necessary, alkali-soluble polymers or copolymers such as novolac resins, phenol resins, imide resins, carboxylic acid-containing resins, etc. May be additionally contained. The present invention is characterized in that a method different from the conventional method is adopted in preparing the above-mentioned acid-sensitive two-component and three-component copolymers used as the base resin. That is, in the conventional method, the selected monomers for forming the acid-sensitive copolymer were collectively polymerized in the presence of a suitable polymerization initiator. The first and second monomer units for forming a copolymer and optionally a third
It is characterized in that the monomer corresponding to each of the monomer units is added to the polymerization reaction system according to the consumption amount of those monomers to gradually perform the polymerization. When the polymerization is carried out by such a method, the heat of reaction during the polymerization reaction cannot be controlled by the conventional method, and in fact, at the initial stage of the reaction,
Sudden temperature rise (80 minutes within 30 minutes from the start of the reaction
Temperature rises from 90 ° C to 90 ° C), and as a result, the inconveniences described in the section of the prior art occur, but on the contrary, a relatively low temperature, usually around 80 ° C, is stabilized. ,
It can be maintained with only a fluctuation of around 1 ° C. Also,
According to the knowledge of the present inventor, this method is particularly effective when the polymerization reaction system is a radical solution polymerization system.

Further, in such a polymerization reaction system,
Although the polymerization reaction may be carried out in the presence of only a polymerization initiator as in the conventional case, it is preferably carried out in the presence of a chain transfer agent in combination with this polymerization initiator, and at that time, it is acid-sensitive. It is advantageous to control the molecular weight of the copolymer by adjusting the addition of polymerization initiators and chain transfer agents. Here, the polymerization initiator to be used can be arbitrarily selected from a wide range of commonly used ones, but preferably, for example, the most industrial radical solution polymerization can be used to obtain the copolymer. When, the following polymerization initiators are used. AIBN (N, N'-azobisisobutyronitrile):

[0056]

[Chemical 32]

MAIB (dimethyl-2,2-azoisobisbutyrate):

[0058]

[Chemical 33]

The chain transfer agent can also be arbitrarily selected from a wide range of commonly used ones, but is preferably, for example, 2-ethylhexyl mercaptopropionate. The addition amount of the polymerization initiator and the chain transfer agent can be widely changed depending on the desired result. Also, the polymerization conditions themselves are
The optimum condition can be determined each time according to the conventional method.

When the acid-sensitive copolymer is prepared in this manner, the dispersity of the copolymer can be suppressed to a low level of 1.7 or less. The fact that such a narrow dispersity can be obtained without accompanying treatment such as a purification step is notable in comparison with the conventional technology that accepts the decrease in yield due to the increase in man-hours. Is worth.

The preparation of the acid-sensitive copolymer according to the present invention is
It can be carried out using a polymerization apparatus which has been conventionally used. Also, when this is done on a laboratory scale, it can be done similarly using commonly available equipment. For example, FIG. 1 is a schematic diagram showing an example of a polymerization apparatus for preparing an acid-sensitive copolymer according to the present invention. In the illustrated polymerization apparatus, the reaction vessel 1 is placed in an oil bath 6
In addition, the oil bath 6 is placed on the heating device 7. The reaction vessel 1 is a three-necked flask, a dropping funnel 2 is provided at one port, a Liebig condenser 3 is provided at the other port, and a thermometer 4 is provided at the other port.
Are installed respectively. Furthermore, the reaction container 1
A stir bar 5 is also placed at the bottom of the. Using such a polymerization apparatus, the reaction solvent is put into the reaction vessel 1, and the monomer solution is dropped from the dropping funnel 2 according to the procedure of the present invention.
The desired copolymer can be recovered. Further, for dropping the monomer solution, a means such as a liquid feed pump (not shown) may be adopted instead of the dropping funnel 2.

In the chemically amplified resist material according to the present invention, the acid sensitive two-component and three-component copolymers described above use an acid generator in combination therewith. The acid generator used in the present invention (also referred to as "photo acid generator")
Is an acid generator commonly used in resist chemistry, that is, a substance that produces a protonic acid upon irradiation with radiation such as ultraviolet rays, deep ultraviolet rays, vacuum ultraviolet rays, electron beams, X-rays, and laser beams. it can. Acid generators suitable in the practice of the present invention include, but are not limited to, those listed below. (1) diazonium salt represented by the formula: Ar-N ₂ ⁺ X ^- in (the above formula, Ar is a substituted or unsubstituted aromatic group, such as a phenyl group, or an alicyclic group, and X is halogen such as Cl, Br, I or F,
BF ₄ , BF ₆ , PF ₆ , AsF ₆ , SbF ₆ , CF ₃
SO _3, represents and ClO ₄ or an organic sulfonic acid anion). (2) Iodonium salt represented by the following formula:

[0063]

[Chemical 34]

(In the above formula, Ar and X are the same as defined above). (3) Sulfonium salt represented by the following formula:

[0065]

[Chemical 35]

[0066]

[Chemical 36]

[0067]

[Chemical 37]

[0068]

[Chemical 38]

[0069]

[Chemical Formula 39]

[0070]

[Chemical 40]

(In the above formula, R, Ar and X are respectively the same as defined above, and R ¹ , R ² and R ³ are
They may be the same or different and each represents a hydrogen atom or any substituent, for example, a halogen atom,
Represents an alkyl group, an aryl group or the like, for example, R is a methyl group or the like, and R ¹ , R ² and R ³ are phenyl groups or the like). (4) Sulfonic acid ester represented by the following formula:

[0072]

[Chemical 41]

(In the above formula, Ar and R are the same as defined above). (5) Oxazole derivative represented by the following formula:

[0074]

[Chemical 42]

(In the above formula, X has the same meaning as defined above, provided that one of the --CX ₃ groups may be a substituted or unsubstituted aryl group or alkenyl group). (6) s-triazine derivative represented by the following formula:

[0076]

[Chemical 43]

(In the above formula, X has the same meaning as defined above, provided that one of the --CX ₃ groups may be a substituted or unsubstituted aryl group or alkenyl group). (7) a disulfone derivative represented by the _{formula: Ar-SO 2 -SO 2 -Ar} ( In the above formula, Ar are as defined above). (8) An imide compound represented by the following formula:

[0078]

[Chemical 44]

(In the above formula, X has the same definition as above). (9) Others, such as oxime sulfonate, diazonaphthoquinone, and benzoin tosylate. More specifically, some examples of these acid generators are the following compounds. Triphenylsulfonium triflate:

[0080]

[Chemical formula 45]

Triphenylsulfonium hexafluoroantimonate:

[0082]

[Chemical formula 46]

Triphenylphosphonium hexafluorophosphate:

[0084]

[Chemical 47]

Diphenyl iodohexafluorophosphate:

[0086]

[Chemical 48]

Benzoin tosylate:

[0088]

[Chemical 49]

Naphthylimidyl triflate:

[0090]

[Chemical 50]

Cyclohexylmethyl (2-oxocyclohexyl) -sulfonium trifluoromethanesulfonate:

[0092]

[Chemical 51]

The chemically amplified resist material according to the present invention is
It can be prepared using the acid-sensitive copolymer as described above and an acid generator as starting materials. Preparation of such a resist material, for example, by adding an acid generator to the copolymer prepared according to the method of the present invention, further adding an organic solvent as a dispersion medium for the coating film, for example, ethyl lactate, and dissolved
It can be a resist solution. In the preparation of the chemically amplified resist material, the amount of the acid generator added to the acid-sensitive copolymer can be changed over a wide range,
Generally in the range of about 1 to 30% by weight, preferably about 1 to 1
It is in the range of 5% by weight.

The solvent used for preparing such a resist solution can be variously changed depending on the type of resist, coating conditions and other factors, but is preferably ethyl lactate or propylene glycol monomethyl ether. Organic solvents such as acetate (PGMEA), ethylpyruvate, and cyclohexanone. In particular, when ethyl lactate, propylene glycol monomethyl ether acetate (PGMEA), ethyl pyruvate, or the like is used, a resist pattern with higher contrast can be obtained. If necessary, a cosolvent may be added. It is also effective to add a surfactant in order to prevent striation after coating the resist solution. Furthermore, if necessary, a weakly basic compound such as a substituted amine compound that is an acid quencher, a nitrile compound, or N-methylpyrrolidone may be added.

In the present invention, the chemically amplified resist material of the present invention as described above is applied on a substrate to be processed to form a resist film, and the resist film formed on the substrate to be processed is used in the resist film. Selectively exposing to a radiation capable of causing the generation of an acid from an acid generator contained in, and developing the latent image formed in the exposing step, a resist pattern comprising: It is in the forming method.

In the method of forming a resist pattern according to the present invention, the exposed resist film is heated at an elevated temperature between the exposure step and the development step, that is, the post-exposure bake (PEB, described below) is performed. (Sometimes referred to simply as "post bake") is essential. The formation of the resist pattern according to the present invention can be carried out using a general method for a chemically amplified resist material, but preferably it can be carried out as follows.

First, the solution of the chemically amplified resist material prepared as described above is applied onto the substrate to be processed. The substrate to be used here may be any substrate usually used in semiconductor devices and other devices, and specifically, a semiconductor substrate such as a silicon substrate, a glass substrate, or a substrate formed on the substrate. Various layer films such as an oxide film, a polysilicon layer, a nitride film, and an aluminum wiring can be used. These substrates may or may not already have circuitry built into them. In some cases, these substrates are preferably pretreated with an adhesion promoter such as hexamethyldisilazane (HMDS) in order to improve the adhesion to the resist.

The coating of the resist solution can be carried out by using a commonly used coating device such as a spin coater, a dip coater and a roller coater. Preferably, the resist solution can be dropped onto the substrate to be processed using a spin coater. The thickness of the formed resist film can be widely changed depending on factors such as the purpose of the obtained resist pattern, but is usually about 0.3 to 2.0 μm.
Is the range.

Then, preferably, the resist film formed in the above-mentioned step is exposed to about 40 before selectively exposing to radiation.
~ 170 ° C, preferably about 6 at a temperature of about 60-120 ° C.
Prebake for 0 to 180 seconds. For this prebaking, a heating means such as a hot plate can be used. Further, if a cover coat is further applied on the resist film, for example, a solution of an olefin resin is applied on the resist film by a spin coating method, and then the resin coating film is baked at a predetermined temperature. It can be used as a cover coat.

After the resist film is formed and pre-baked, the resist film is selectively exposed to radiation through a reticle by a conventional exposure device. Suitable exposure apparatuses are commercially available ultraviolet (far ultraviolet / vacuum ultraviolet) exposure apparatuses, X-ray exposure apparatuses, electron beam exposure apparatuses, excimer steppers, and the like.
As the exposure condition, an appropriate condition can be selected each time. As a result of this selective exposure, an acid is generated from the acid generator contained in the resist film, and finally the circuit pattern on the reticle is printed.

Then, the resist film after exposure is immediately post-exposure baked (PEB) to cause an acid-catalyzed elimination reaction of the protective group. This post-exposure bake is
It can be performed in the same manner as the above prebaking. For example, the baking temperature is about 60 to the decomposition temperature of the base resin of the resist, preferably about 90 to 150 ° C.
When a cover coat is used, the cover coat is peeled off with a predetermined peeling solution after the post-exposure bake and before the development.

After completion of the post-exposure bake, the post-exposure resist film is liquid-developed by a conventional method. As the developing solution used here, an appropriate developing solution can be arbitrarily selected from the developing solutions generally used in this technical field.
Particularly preferred developers are ammonium compounds of the formula:

[0103]

[Chemical 52]

(In the formula, R ₂ , R ₃ , R ₄ and R ₅ are respectively
A morpholine compound of the following formula, which may be the same or different and represents a substituted or unsubstituted alkyl group having 1 to 6 carbon atoms):

[0105]

[Chemical 53]

A developing solution containing an aqueous solution or an alcohol solution of a mixture thereof. Preferred examples of the ammonium compound as the developer are not limited to those listed below, but tetramethylammonium hydroxide (TMAH), tetraethylammonium hydroxide (TEAH), tetrapropylammonium hydroxide (TPAH). ), Tetrabutylammonium hydroxide (TBAH), and the like.

These developers are dissolved in water or dissolved in alcohol such as methanol, ethanol or isopropyl alcohol to prepare a developing solution. The concentration of the dissolved developer can be widely varied, but is generally in the range of about 0.1 to 15% by weight, preferably in the range of about 0.1 to 10% by weight. Usually, a 2.38 wt% aqueous solution of TMAH is used as a developer. The developing time is not particularly limited, but is generally in the range of about 10 seconds to 20 minutes, preferably 30 seconds to.
The range is 5 minutes. As a result of the development, the exposed area of the resist film is dissolved and removed, and a desired resist pattern can be obtained. Finally, the obtained resist pattern is also rinsed with pure water according to a conventional method and dried.

[0108]

EXAMPLES Next, the present invention will be described with reference to the examples. It should be understood that the present invention is not limited to these examples. Example 1 2-Methyl-2-adamantyl methacrylate / mevalonic lactone methacrylate copolymer (2MAdMA
Preparation of MLMA): A reaction vessel as shown in FIG. 1 was prepared, and 55 g of 1,4-dioxane (as a solvent) was added thereto. Furthermore, since it is used as a dropping liquid,
0.08 mol of 2-methyl-2-adamantyl methacrylate (2MAdMA), 0.08 mol of mevalonic lactone methacrylate (MLMA), 1 mol% (based on the total amount of monomers) of AIBN (N, N) '-Azoisobutyronitrile, as a polymerization initiator), 2 mol% (based on the total amount of monomers) of 2-ethylhexyl mercaptopropionate (as a chain transfer agent), and 20 g of 1,
4-dioxane was mixed. The reaction vessel containing 1,4-dioxane was immersed in an oil bath whose temperature was controlled at 70 ° C. and heated, and the dropping solution was added dropwise at a temperature of 70 ° C. over about 2 hours. Furthermore, the reaction was continued at a temperature of 70 ° C. for about 4 hours. After completion of the reaction, the reaction system was returned to room temperature,
The reaction solution was poured into about 1 liter of methanol to precipitate a polymer. After the precipitate was dried, the polymer was dissolved in tetrahydrofuran (THF), and the solution was poured again into about 1 liter of methanol. The precipitate formed again was filtered off and dried. When the same operation was repeated twice, a resinous product was obtained with a yield of 62%. 1H-
When analyzed by NMR, it was confirmed to be a 2-methyl-2-adamantyl methacrylate / mevalonic lactone methacrylate copolymer (composition ratio 50:50). Furthermore, when the molecular weight of this copolymer was measured by GPC, the weight average molecular weight (Mw) was 6069 and the dispersity (Mw / Mn) was 1.32. Example 2 Formation of resist pattern: The copolymer (2MAdMA-MLMA) prepared in Example 1 was dissolved in ethyl lactate (EL) to obtain a 14 wt% solution, and the resulting solution was used as an acid generator. 2% by weight of the copolymer of triphenylsulfonium triflate (TPSSO ₃ CF ₃ )
And was dissolved in ethyl lactate so that the resin content was 14% by weight. The obtained resist solution was spin-coated on a silicon substrate whose adhesion was enhanced by pretreatment with hexamethyldisilazane (HMDS), and prebaked on a hot plate at 90 ° C. for 60 seconds. A resist film having a film thickness of 0.4 μm was obtained.

Next, after coating the obtained resist film with a polyolefin resin to form a protective film,
ArF excimer laser exposure device (Nikon, NA =
0.55), ArF laser light having a wavelength of 193 nm was selectively exposed through a reticle on which a pattern of an IC circuit was drawn. Immediately after completion of the exposure, the resist film was post-exposure baked (PEB) on a hot plate at 90 ° C. for 60 seconds. After peeling off the protective film, the resist film was developed for 60 seconds with a developer composed of a 2.38 wt% tetramethylammonium hydroxide (TMAH) aqueous solution, NMD-3 manufactured by Tokyo Ohka Kabushiki Kaisha, and further with pure water for 30 seconds. I rinsed. As a result, a desired resist pattern corresponding to the laser beam pattern used for exposure was obtained with a resolution of 0.17 μm L & S (line and space). The exposure dose at this time was 13 mJ / cm ² . Comparative Example 1 2-Methyl-2-adamantyl methacrylate / mevalonic lactone methacrylate copolymer (2MAdMA
-MLMA) preparation: 0.08 mol of 2-methyl-2-
Adamantyl methacrylate (2MAdMA), 0.0
8 mol of mevalonic lactone methacrylate (MLM
A) and 15 mol% (relative to the total amount of monomers) of AIB
N (N, N'-azoisobutyronitrile was dissolved in 1,4-dioxane (as a solvent) to give a 3 mol / L solution of 1,4-dioxane. The mixture was immersed in an oil bath whose temperature was controlled at 80 ° C. and heated, and the reaction was carried out at a temperature of 80 ° C. for about 6 hours. The polymer was precipitated by pouring it into about 1 liter of methanol, and after the precipitate was dried, the polymer was dissolved in tetrahydrofuran (THF), and the solution was poured into about 1 liter of methanol again. The precipitate was filtered off and dried, and the same operation was repeated twice, yielding 40
% Of resinous material was obtained. 1H-NMR of this resinous material
As a result, it was confirmed to be a 2-methyl-2-adamantyl methacrylate / mevalonic lactone methacrylate copolymer (composition ratio 50:50). Furthermore, when the molecular weight of this copolymer was measured by GPC, the weight average molecular weight (Mw) was 17252 and the dispersity (Mw / Mn) was 3.26. Comparative Example 2 Formation of resist pattern: The copolymer (2MAdMA-MLMA) prepared in Comparative Example 1 was dissolved in ethyl lactate (EL) to obtain a 14 wt% solution, and the obtained solution was used as an acid generator. 2% by weight of the copolymer of triphenylsulfonium triflate (TPSSO ₃ CF ₃ )
And was dissolved in ethyl lactate so that the resin content was 14% by weight. The obtained resist solution was spin-coated on a silicon substrate whose adhesion was enhanced by pretreatment with hexamethyldisilazane (HMDS), and prebaked on a hot plate at 90 ° C. for 60 seconds. A resist film having a film thickness of 0.4 μm was obtained.

Then, after coating the obtained resist film with a polyolefin resin to form a protective film,
ArF excimer laser exposure device (Nikon, NA =
0.55), ArF laser light having a wavelength of 193 nm was selectively exposed through a reticle on which a pattern of an IC circuit was drawn. Immediately after completion of the exposure, the resist film was post-exposure baked (PEB) on a hot plate at 90 ° C. for 60 seconds. After peeling off the protective film, the resist film was developed for 60 seconds with a developer composed of a 2.38 wt% tetramethylammonium hydroxide (TMAH) aqueous solution, NMD-3 manufactured by Tokyo Ohka Kabushiki Kaisha, and further with pure water for 30 seconds. I rinsed. As a result, a resist pattern corresponding to the laser beam pattern used for exposure was obtained with a resolution of 0.17 μm L & S (line and space). However, in this resist pattern, the upper part was rounded, and residues between the patterns were also recognized. The exposure amount at this time is 1
It was 8 mJ / cm ² .

[0111]

According to the present invention, by preparing an acid-sensitive copolymer used as a base resin under specific polymerization conditions, high resolution, high sensitivity, and excellent dry etching resistance can be obtained. Thus, it is possible to provide a chemically amplified resist material having no variation in characteristics among resin lots.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a configuration of a polymerization apparatus used for preparing a base resin of a resist material of the present invention.

[Explanation of symbols]

1 ... Reaction vessel 2 ... Dripping funnel 3 ... Liebig cooler 4 ... thermometer 5 ... Stirrer 6 ... oil bath 7 ... Heating device

Continuation of the front page (56) Reference JP-A-9-90637 (JP, A) JP-A-9-73173 (JP, A) JP-A-10-17623 (JP, A) JP-A-57-52050 (JP , A) JP 62-295046 (JP, A) JP 10-133377 (JP, A) JP 10-161313 (JP, A) JP 11-119434 (JP, A) JP 10-207069 (JP, A) JP-A-10-274852 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) G03F ^7/ 00-7/42

Claims (18)

(57) [Claims] 1. At least the following first and second monomer units: containing an alkali-soluble group protected by a protecting group having an alicyclic hydrocarbon structure, wherein the protecting group is eliminated by an acid, and the copolymerization The copolymer contains a first monomer unit having a structural unit that makes the polymer alkali-soluble, and an alkali-soluble group protected by a protective group having a lactone structure, and the protective group is eliminated by an acid to give an alkali-containing copolymer. A chemically amplified type compound comprising an acid-sensitive copolymer formed by copolymerization of a second monomer unit having a structural unit capable of being soluble, and an acid generator capable of generating an acid upon exposure to radiation. in the resist material, the acid-sensitive copolymer, a monomer corresponding to each of the first and second monomer units in accordance with the consumption of these monomers Chemically amplified resist composition which is characterized in that which was prepared by adding the radical solution polymerization reaction system. 2. The acid-sensitive copolymer contains the first and second monomer units, and an alkali-soluble group protected by a protecting group different from the protecting groups of the monomer units, and the alkali-containing group. It is formed by copolymerization of a third monomer unit having a structural unit capable of eliminating the soluble group with an acid to make the copolymer alkali-soluble or a structural unit containing a polar group or an alkali-soluble group. The chemically amplified resist material according to claim 1. 3. The alicyclic hydrocarbon structure of the protective group contained in the first monomer unit has the following groups: (1) adamantane and its derivative (2) norbornane and its derivative (3) perhydroanthracene and Derivatives thereof (4) Perhydronaphthalene and derivatives thereof (5) Tricyclo [5.2.1.0 ^2,6 ] decane and derivatives thereof (6) Cyclohexane, methylcyclohexane, dimethylcyclohexane, bicyclohexane and derivatives thereof (7) 3. Spiro [4,5] nonane and its derivative (8) Spiro [4,5] decane and its derivative are derived from one member selected from the group consisting of: Chemically amplified resist material. 4. The lactone structure contained in the second monomer unit has the following formula (I) or (II): [Chemical 2] (In the above formula, R ₁ represents a hydrogen atom or a substituted or unsubstituted hydrocarbon group having 1 to 4 carbon atoms, and n is an integer of 1 to 4) The chemically amplified resist material according to any one of claims 1 to 3, which is represented by: 5. The protective group contained in the third monomer unit is a t-butyl group, a 3-oxocyclohexyl group or a tetrahydropyranyl group, according to any one of claims 2 to 4. The chemically amplified resist material according to item 1. 6. The alkali-soluble group contained in the monomer unit is a carboxylic acid group, a sulfonic acid group, an amide group, an imide group or a phenol group, according to any one of claims 1 to 5. The chemically amplified resist material described. 7. The acid-sensitive copolymer has the following formula (III):
Two-component copolymer represented by: (In the above formulas, R may be the same or different and represents a hydrogen atom, a halogen atom or a substituted or unsubstituted hydrocarbon group having 1 to 4 carbon atoms, and R _I is It represents a substituted or unsubstituted hydrocarbon group having 1 to 4 carbon atoms, and Z represents a plurality of atoms necessary for completing the alicyclic hydrocarbon group together with the indicated carbon atom. LAC is a lactone structure represented by the following formula (I) or (II): [Chemical 5] Wherein R ₁ represents a hydrogen atom or a substituted or unsubstituted hydrocarbon group having 1 to 4 carbon atoms, and n is an integer of 1 to 4 , And k and m are respectively the number of monomer units constituting the acid-sensitive two-component copolymer and their ratio k:
m is 45 to 90:10 to 55 in terms of a molar ratio), and the chemically amplified resist material according to claim 1. 8. The acid-sensitive copolymer is a three-component copolymer represented by the following formula (IV): embedded image (In the above formulas, R may be the same or different and represents a hydrogen atom, a halogen atom or a substituted or unsubstituted hydrocarbon group having 1 to 4 carbon atoms, and R _I is It represents a substituted or unsubstituted hydrocarbon group having 1 to 4 carbon atoms, and Z represents a plurality of atoms necessary for completing the alicyclic hydrocarbon group together with the indicated carbon atom. LAC is a lactone structure represented by the following formula (I) or (II): [Chemical 8] Wherein R ₁ represents a hydrogen atom or a substituted or unsubstituted hydrocarbon group having 1 to 4 carbon atoms, and n is an integer of 1 to 4 , A represents a protecting group other than the Z and LAC structures which can be removed by an acid, and k, l and m respectively represent the number of monomer units constituting the acid-sensitive ternary copolymer. And their ratio k: l: m is expressed as a molar ratio,
45 to 75:15 to 40:10 to 35, and the repeating order of the described monomer units can be arbitrarily changed). Resist material. 9. At least the following first and second monomer units: containing an alkali-soluble group protected by a protecting group having an alicyclic hydrocarbon structure, and the protecting group being eliminated by an acid, The copolymer contains a first monomer unit having a structural unit that makes the polymer alkali-soluble, and an alkali-soluble group protected by a protective group having a lactone structure, and the protective group is eliminated by an acid to give an alkali-containing copolymer. A chemically amplified type compound comprising an acid-sensitive copolymer formed by copolymerization of a second monomer unit having a structural unit capable of being soluble, and an acid generator capable of generating an acid upon exposure to radiation. In the method for preparing a resist material, the acid-sensitive copolymer is prepared from the monomers corresponding to the first and second monomer units, respectively. Method for preparing a chemically amplified resist material characterized by comprising the step of preparing by adding the radical solution polymerization reaction system in accordance with the fee amount. 10. The acid-sensitive copolymer is a three-component copolymer, and the three-component copolymer is a monomer corresponding to each of the first and second monomer units, A structural unit or a polar group or an alkali-soluble group containing an alkali-soluble group protected by a protecting group different from the protecting group of the monomer unit, and the protecting group is eliminated by an acid to make the copolymer alkali-soluble. And a monomer corresponding to a third monomer unit having a structural unit containing ## STR3 ## and a monomer corresponding to the amount of consumption of those monomers are added to the radical solution polymerization reaction system. The method for preparing a chemically amplified resist material according to claim 9. 11. In the radical solution polymerization reaction system, the polymerization of the monomer is carried out in the presence of a polymerization initiator and a chain transfer agent, and the molecular weight of the acid-sensitive copolymer is controlled by the polymerization initiator. The method for preparing a chemically amplified resist material according to claim 9 or 10 , wherein the method is performed by adjusting the addition of a chain transfer agent. 12. The acid-sensitive copolymer has a dispersity of 1.
Method for preparing a chemically amplified resist material according to any one of claims 9 to 11, characterized in that 7 or less. 13. At least the following first and second monomer units: containing an alkali-soluble group protected by a protecting group having an alicyclic hydrocarbon structure, wherein the protecting group is eliminated by an acid, The copolymer contains a first monomer unit having a structural unit that makes the polymer alkali-soluble, and an alkali-soluble group protected by a protective group having a lactone structure, and the protective group is eliminated by an acid to give an alkali-containing copolymer. A second monomer unit having a structural unit that renders it soluble; and a monomer corresponding to each of the first and second monomer units at the time of the copolymerization. the radical according to the consumption of these monomers
A chemically amplified resist material containing an acid-sensitive copolymer prepared by adding it to a solution polymerization reaction system and an acid generator that generates an acid upon exposure to radiation is applied to a substrate to be processed to form a resist film. Forming, selectively exposing the resist film on the substrate to be processed to radiation capable of causing the acid generator to generate an acid, and developing the latent image formed in the exposing step. A method for forming a resist pattern, comprising: 14. The acid-sensitive copolymer, life and death contains the first and second monomer units, the alkali-soluble group protected by a protecting group different from protecting groups of the monomers units It is formed by the copolymerization of a third monomer unit having a structural unit capable of eliminating the protective group with an acid to make the copolymer alkali-soluble or a structural unit containing a polar group or an alkali-soluble group. 14. The method of forming a resist pattern according to claim 13 , wherein: 15. The acid-sensitive copolymer is represented by the following formula (III
Two-component copolymer represented by: (In the above formulas, R may be the same or different and represents a hydrogen atom, a halogen atom or a substituted or unsubstituted hydrocarbon group having 1 to 4 carbon atoms, and R _I is It represents a substituted or unsubstituted hydrocarbon group having 1 to 4 carbon atoms, and Z represents a plurality of atoms necessary for completing the alicyclic hydrocarbon group together with the indicated carbon atom. LAC is a lactone structure represented by the following formula (I) or (II): [Chemical 11] Wherein R ₁ represents a hydrogen atom or a substituted or unsubstituted hydrocarbon group having 1 to 4 carbon atoms, and n is an integer of 1 to 4 , And k and m are respectively the number of monomer units constituting the acid-sensitive two-component copolymer and their ratio k:
m is 45-75: 25-55 expressed in a molar ratio), The method for forming a resist pattern according to claim 13 . 16. The acid-sensitive copolymer has the following formula (IV):
A three-component copolymer represented by: (In the above formulas, R may be the same or different and represents a hydrogen atom, a halogen atom or a substituted or unsubstituted hydrocarbon group having 1 to 4 carbon atoms, and R _I is It represents a substituted or unsubstituted hydrocarbon group having 1 to 4 carbon atoms, and Z represents a plurality of atoms necessary for completing the alicyclic hydrocarbon group together with the indicated carbon atom. LAC is a lactone structure represented by the following formula (I) or (II): [Chemical 14] Wherein R ₁ represents a hydrogen atom or a substituted or unsubstituted hydrocarbon group having 1 to 4 carbon atoms, and n is an integer of 1 to 4 , A represents an acid-eliminating protecting group other than Z and LAC, and k, l and m are the number of monomer units constituting the acid-sensitive ternary copolymer, respectively. And the ratio k: l: m of them is 45 in terms of molar ratio.
To 75:15 to 40:10 to 35, and the repeating order of the described monomer units can be changed arbitrarily). 15. Formation of a resist pattern according to claim 13 or 14. Method. 17. The polydispersity of the acid-sensitive copolymer is 1.
It is 7 or less, Any one of Claims 1-8 characterized by the above-mentioned.
The chemically amplified resist material according to item 1. 18. The polydispersity of the acid-sensitive copolymer is 1.
It is 7 or less, In any one of Claims 13-16 characterized by the above-mentioned.
2. The method for forming a resist pattern according to item 1.