JP5437165B2 - Copolymer composition analysis method and program thereof - Google Patents

Description

  The present invention relates to a polymer composition analysis method for analyzing characteristics of a copolymer produced by synthesizing a plurality of different monomers and a program thereof.

In general, in order to measure the properties of polymers (polymers), especially copolymers, online in a polymerization reactor system and control the polymerization reaction, it is necessary to analyze those measured properties.
For example, as one type of copolymer, it is conceivable to evaluate characteristics of a resist (resist composition) which is a lithography composition used in the process of manufacturing a semiconductor element.
In the manufacturing process of semiconductor elements, liquid crystal elements, etc., in recent years, pattern formation by lithography has been rapidly miniaturized. In order to realize the miniaturization of the semiconductor element and the like, it is necessary to shorten the wavelength of the irradiation light to the resist used for forming a pattern such as a wiring, and lithography characteristics such as the reaction of the resist to light and the solubility described later are important.

Recently, KrF excimer laser (wavelength: 248 nm) lithography technology has been introduced, and ArF excimer laser (wavelength: 193 nm) lithography technology and EUV (Extreme Ultraviolet) excimer laser (wavelength: 13 nm) lithography technology is being studied.
For this reason, as a resist composition that can suitably cope with the shortening of the wavelength of irradiation light and the miniaturization of patterns, a polymer in which an acid-eliminable group is eliminated by the action of an acid and becomes alkali-soluble, a photoacid generator, A so-called chemically amplified resist composition containing benzene has been proposed, and its development and improvement are underway.

As a chemically amplified resist polymer used in ArF excimer laser lithography, an acrylic polymer that is transparent to light having a wavelength of 193 nm has attracted attention.
For example, Patent Document 1 discloses that (A) an alicyclic hydrocarbon group having a lactone ring is ester-bonded as a monomer (monomer), and (B) acid is removed by the action of an acid. (Meth) acrylic acid ester having an ester bond with a detachable group, and (C) (meth) acrylic acid ester having a hydrocarbon group having a polar substituent or an oxygen atom-containing heterocyclic group bonded with an ester. The resist copolymer used is described.

By the way, a polymer of (meth) acrylic acid ester is generally polymerized by a radical polymerization method. In general, in a multi-component polymer having two or more monomers, the regularity of the chain varies depending on the copolymerization reactivity ratio between the monomers. At this time, in the produced polymer, each monomer unit is continuously arranged, that is, a copolymer having many chains in which the same monomers are continuously arranged to form a block is a light of the resist composition. The resist performance (lithographic properties) such as the reaction to the solvent and solubility in the solvent is likely to be lowered. For this reason, examination which evaluates the chain structure in the copolymer for resists for creating the composition for resists has been made.
In general, the chain structure of a copolymer for a resist is divided into a spectrochemical analysis method such as a nuclear magnetic resonance (NMR) method and an infrared absorption (IR) method, and a separation analysis method such as a pyrolysis gas chromatography (PyGC) method. Alternatively, Non-patent Document 1 describes a method of searching for a characteristic signal for each factor from signals obtained by mass spectrometry (MS) and calculating the signal intensity from the signal.

However, in the method described in Non-Patent Document 1, as the number of structural units of the copolymer increases, even when the number of structural units is small, characteristic signals of each component overlap. In some cases, the signals obtained from the measurement results cannot be clearly separated.
In addition, in the method described in Non-Patent Document 1, it takes time to analyze the data obtained by measurement, and the accuracy is low in terms of the accuracy of the quantitative value obtained from the analysis result. When quality control is performed, the obtained results may not be used effectively.

  On the other hand, in recent years, mathematical or statistical methods called multivariate analysis or chemometrics have been applied, and obtained from chemical data such as spectra and pyrolysis gas chromatograms obtained by various measurements of infrared absorption and mass spectrometry. Analyzes using methods aimed at maximizing the amount of chemical information available are being used. As a method for performing this analysis, for example, Patent Document 2 and Patent Document 3 describe a method for identifying a polymer material from a near-infrared spectrum, a method for measuring density, and the like.

JP 2002-145955 A JP 2002-90299 A JP 2002-340792 A

New edition polymer analysis handbook (Japan Society for Analytical Chemistry, Polymer Analysis Research Roundtable, Kinokuniya, p.233, p.694, p.855, etc.)

By using the method of analysis of Patent Document 2 and Patent Document 3 described above, the resist polymer thus produced and other additives are actually adjusted to create a resist composition. This resist composition It is no longer necessary to develop the resist by irradiating (actually used resist) with light.
Thus, the analysis method in each of Patent Document 2 and Patent Document 3 can evaluate the performance of the prepared resist composition, is simple, and has the effect of components other than the resist copolymer. Therefore, it is effective to evaluate the characteristics of the resist composition alone (lithographic characteristics including the sensitivity of light in exposure and solubility in a solvent in development) as a resist composition.

In addition, a resist used as a thin film formation such as an antireflection film, a gap fill film, and a top coat film formed on an upper layer or a lower layer of a resist composition applied on a semiconductor material in a lithography process in manufacturing an integrated circuit Evaluation of lithographic compositions other than the resist composition is as important as for the resist composition.
That is, it is important whether or not a lithographic composition containing a lithographic copolymer has characteristics (lithographic characteristics) for performing high-precision fine processing.
As in the case of evaluating the resist composition, this lithographic composition is also prepared by actually adjusting the lithographic copolymer to produce a lithographic composition, and without performing the lithography step with this lithographic composition. In any case, it is necessary to be able to evaluate the lithographic properties of the lithographic composition using the lithographic copolymer.

  This antireflection film is a lithographic composition that is formed under the resist composition film and used to suppress the reflection of light from the semiconductor material and improve the exposure accuracy of the resist composition. The gap fill film is a lithographic composition that is formed in the lower layer of the resist composition film and is used to flatten the unevenness of the semiconductor material and improve the exposure accuracy of the resist composition. The topcoat film is a copolymer formed on the resist composition film and used to protect the surface of the resist composition. These antireflection films, gap fill films, and topcoat films are lithographic compositions necessary for improving the exposure accuracy of lithography structures in the production of integrated circuits, and are indispensable for miniaturization of integrated circuits. is there.

However, in the analysis methods described in Patent Document 2 and Patent Document 3, when the composition of the copolymer used for adjusting the composition is quantified or the chain distribution is estimated, the constituent units contained in the copolymer are analyzed. Depending on the type, the thermal decomposition efficiency by the heat treatment given in the analysis is different, or the thermal decomposition product reflecting the structural unit cannot be obtained quantitatively.
For this reason, the analysis methods described in Patent Document 2 and Patent Document 3 need not only use correction coefficients and three-dimensional plot diagrams for analysis of evaluation results, but also quantify or estimate the results obtained. However, in order to obtain data to be compared with the obtained results, an enormous number of samples are required, which may cause problems in practical use.

The present invention has been made in consideration of the above circumstances, and by simply estimating the randomness of the chain structure of the copolymer, the copolymer can be composed without actually producing the composition. It is to provide a method for evaluating the properties of a product.
That is, the present invention uses the NMR spectrum obtained by NMR measurement to compare the comparison space including the coordinate points of homopolymers of all the monomers used in the principal component space, A comparison distance, which is a distance from the coordinate point of the coalescence, is determined, and the randomness of the arrangement of the monomers in the copolymer chain structure is determined by this comparison distance, and the composition adjusted using the copolymer by this randomness Since the characteristics of the product are evaluated, the composition can be evaluated more easily than in the past.
In addition, the present invention does not give a high temperature by adjusting the measurement sample when quantifying the monomer in the polymer or estimating the chain distribution. In addition, there is no measurement error, such as a thermal decomposition product that reflects the structural unit cannot be obtained quantitatively, so there is no need to prepare a large number of samples for correction processing, etc. The composition obtained can be evaluated.
Here, the randomness indicates a property of a chain state in which the types of adjacent monomers are different, that is, there are few blocks in which a plurality of the same monomers are adjacently bonded in a chain structure.

  The copolymer composition analysis method of the present invention is a copolymer composition analysis method of the arrangement state of the monomer units in the copolymer, and the measurement data extraction unit uses the copolymer weight from the NMR spectrum of the copolymer. A measurement data extraction process for extracting an NMR spectrum in a range including the wavelength of each of the monomers constituting the union as copolymer measurement data, and a principal component analysis unit comprising the copolymer measurement data and the single monomer The principal component analysis for chemical shifts and spectral intensities of each NMR spectrum of the body with respect to the monomer measurement data is performed up to the n-th principal component corresponding to the number n of the monomers (n is an integer of 2 or more). The component analysis process and the numerical value conversion unit represent the principal component score of the monomer on the principal component axis in the n-dimensional principal component space formed by the principal component axes from the first principal component to the n-th principal component. Includes all coordinate points A distance calculation process for obtaining an evaluation distance from an n-1 dimensional comparison space to a target coordinate point represented by the main component score of the copolymer, and a characteristic evaluation unit determines the composition of the copolymer according to the evaluation distance. And a characteristic evaluation process for evaluating.

  The copolymer composition analysis method according to the present invention is a method in which the characteristic evaluation unit evaluates the length in which the monomers of the same type are continuously arranged in the composition of the copolymer based on the evaluation distance. It is.

  In the copolymer composition analysis method of the present invention, the characteristic evaluation unit has a threshold for determining the evaluation distance, and is adjusted using the copolymer by comparing the evaluation distance with the threshold. It is a method for evaluating the characteristics of the composition.

  In the copolymer composition analysis method of the present invention, the copolymer is a copolymer for resist, and the characteristic evaluation unit includes lithography characteristics including solubility in a solvent and sensitivity in exposure, the evaluation distance, and the This is a method of evaluating by comparing with a threshold value.

  The program of the present invention is a program for causing a computer used in the copolymer composition analysis method of the arrangement state of the monomer units in the copolymer to execute the measurement data extraction unit, the NMR of the copolymer A measurement data extraction process for extracting, from the spectrum, an NMR spectrum in a range including the wavelength of each of the monomers constituting the copolymer as copolymer measurement data, and a principal component analysis unit comprising the copolymer The principal component analysis with respect to the chemical shift and the spectral intensity of the measurement data and the monomer measurement data of each NMR spectrum of the monomer corresponds to the number n of the monomers (n is an integer of 2 or more). The principal component analysis processing up to the n-th principal component and the numerical value conversion unit in the n-dimensional principal component space formed by the principal component axes from the first principal component to the n-th principal component are the principal components. A distance calculation process for obtaining an evaluation distance from an n-1 dimensional comparison space including all the coordinate points represented by the principal component scores of the monomer to an object coordinate point represented by the principal component scores of the copolymer; The characteristic evaluation unit is a program for causing a computer to execute a characteristic evaluation process for evaluating the composition of the copolymer based on the evaluation distance.

  According to this invention, in the composition of the copolymer (copolymer for resist, copolymer for lithography), randomness of the monomer chain in the copolymer is simply evaluated, and this copolymer is included. The properties of the composition (resist composition, lithography composition) can be evaluated using the copolymer without actually adjusting the composition.

It is a block diagram which shows the structural example of the copolymer composition analyzer by one Embodiment of this invention. It is a figure which shows the coordinate point of each sample in the three-dimensional principal component space which shows the result of the principal component analysis performed with respect to the copolymer produced | generated by superposing | polymerizing three types of monomers. The horizontal axis represents the first principal component axis (PC1), the vertical axis represents the second principal component axis (PC2), and the principal component space of a two-dimensional space composed of the first principal component axis and the second principal component axis. FIG. Molar ratio, molecular weight, evaluation distance L (S) as an evaluation value, dissolution of monomers m-1, m-2 and m-3 in each composition of polymers B-1, B-2 and B-3 It is the table which shows the exposure time as sensitivity (time (minute)) and sensitivity. Molar ratio of monomers m-4, m-5 and m-3, molecular weight, evaluation distance L (S) as evaluation value, dissolution in each composition of polymers B-4, B-5 and B-6 It is the table which shows the exposure time as sensitivity (time (minute)) and sensitivity. The molar ratio of the monomers m-1, m-6 and m-3, the molecular weight, the evaluation distance L (S) as an evaluation value, and the time showing solubility in each composition of the polymers B-7 and B-8 It is a table which shows (minute) and the exposure amount as a sensitivity. The first principal component, the second principal component and the third principal component of each of the homopolymers A-1 to A-3 and the copolymers B-1 to B-3 calculated by the principal component analysis unit 12 It is a figure which shows the main component score of. The first principal component, the second principal component, and the third principal component of each of the homopolymers A-3 to A-5 and the copolymers B-4 to B-6 calculated by the principal component analysis unit 12 It is a figure which shows the main component score of. The first principal component, the second principal component and the third component of each of the homopolymers A-1, A-3 and A-6 and the copolymers B-7 and B-8 calculated by the principal component analysis unit 12 It is a figure which shows the main component score of each main component.

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic block diagram showing a configuration example of a copolymer composition analyzer for analyzing the arrangement state of monomer units in a copolymer according to an embodiment of the present invention.
The copolymer composition analysis apparatus 1 according to this embodiment includes a waveform processing unit 11, a principal component analysis unit 12, a numerical value conversion unit 13, a characteristic evaluation unit 14, an NMR data storage unit 15, and a principal component data storage unit 16. Yes.
The waveform processing unit 11 performs Fourier transform and data processing of the FID (Free Induction Decay) signal of the copolymer or the polymer input from the NMR measurement unit 50, and performs chemical shift amount (frequency component) and chemical shift amount for each. The NMR spectrum data composed of the spectrum intensity is given sample identification information for each sample, and the NMR spectrum data is written and stored in the NMR data storage unit 15 together with the sample identification information.
Further, the NMR data storage unit 15 includes NMR spectral data consisting of the chemical shift amount of the homopolymer consisting only of each monomer and the spectral intensity for each chemical shift amount, which constitutes the copolymer or polymer to be evaluated. Is previously stored together with the respective monomer identification information. Similarly to the copolymer to be evaluated, the waveform processing unit 11 generates NMR spectrum data from the NMR spectrum of the homopolymer measured by the NMR measuring unit 50 and stores it together with the respective monomer identification information. Also good.

The principal component analysis unit 12 performs principal component analysis of a plurality of samples stored in the NMR data storage unit 15, and the principal component score of each principal component for each sample is identified in the principal component data storage unit 16. Write for each information and for each monomer identification information.
Here, in the principal component analysis, the principal component analysis unit 12 obtains the number of principal component axes, that is, the number of principal components, by the number of types of monomers used to generate the copolymer and the polymer. The principal components having the highest contribution rate are selected from the principal components. That is, the number of principal components selected from the principal components obtained from the result of principal component analysis is the same as the number of types of monomers constituting the copolymer to be evaluated, and the number of dimensions of the principal component space described later. Is the same as the number of types of this monomer.
For example, when analyzing the sequence of each monomer in the composition (chain structure) of a copolymer generated from three types of monomers, the principal component analysis unit 12 has three main components as a result of the principal component analysis. Ingredients are selected from those with higher contribution rates.

  In the principal component space formed from the principal component axes of each principal component, the numerical value conversion unit 13 indicates the point indicated by the principal component score on each principal component axis of the copolymer to be evaluated, that is, the evaluation target in the principal component space. The distance from the coordinate point of the copolymer to the space containing the coordinate points of all the samples of the homopolymer consisting of only one type of monomer is determined as the evaluation distance. Here, the principal component space indicates a space constituted by principal component axes orthogonal to each other corresponding to n (2 ≦ n) principal components selected from principal components obtained by principal component analysis. . The coordinate points of the principal component space are coordinate points in the n-dimensional space indicated by the coordinate values of the n principal component axes with the principal component score of each principal component axis as a coordinate value.

For example, FIG. 2 is a diagram showing the coordinate points of each sample in a three-dimensional principal component space, showing the results of principal component analysis performed on a copolymer formed by polymerizing three types of monomers. is there.
When three types of monomers are used and the number of principal components is three, the principal component space is three-dimensional. In this three-dimensional space, the three coordinate points of the three monomers are two-dimensional planes as comparison spaces. (Two-dimensional space) Q is formed. That is, as a space including the coordinate points P (A-1), P (A-2), and P (A-3) of all three types of monomers, a two-dimensional comparison space is obtained from these three coordinate points. A space Q is formed.
In addition, the numerical conversion unit 13 evaluates the evaluation distance L () between the coordinate point P (S) in the three-dimensional space of the copolymer to be analyzed and the two-dimensional comparison space Q formed by the coordinate points of each monomer. S) is calculated. The calculation of the evaluation distance L (S) performed by the numerical value conversion unit 13 will be described in detail later.

The characteristic evaluation unit 14 calculates the chain structure of the composition of the copolymer from the comparison space Q including all the coordinate points of the homopolymer and the evaluation distance L (S) between the coordinate points of the copolymer to be evaluated. The randomness of the sequence of each monomer is determined, and from this determination result, the lithography properties of the composition of the copolymer to be evaluated are evaluated, and the result is output on a display screen (not shown).

Next, a method for producing a copolymer as an evaluation target and a method for evaluating a composition in the present embodiment will be described.
In the present specification, “(meth) acrylic acid” means acrylic acid or methacrylic acid, and “(meth) acryloyloxy” means acryloyloxy or methacryloyloxy.

<Copolymer>
The copolymer of the present invention is composed of n structural units (n is an integer of 2 or more). The upper limit of n is preferably 6 or less in that the effect of the present invention can be easily obtained. In particular, when the copolymer is a resist copolymer or a lithography copolymer used in the production of a semiconductor, it is preferably 5 or less, more preferably 4 or less.
The structural unit of the copolymer to be evaluated is not particularly limited, but when the copolymer is a resist copolymer, it preferably has a structural unit having an acid leaving group. If necessary, it may have a known structural unit such as a structural unit having a lactone skeleton or a structural unit having a hydrophilic group.

<Constitutional unit / monomer>
As the monomer, a monomer corresponding to each structural unit of the copolymer to be obtained is used. The monomer used in the resist copolymer is preferably a compound having a vinyl group, and is preferably a monomer that is easily radically polymerized. In particular, (meth) acrylic acid ester is highly transparent to exposure light having a wavelength of 250 nm or less.
Hereinafter, when a copolymer is a copolymer for resists, the structural unit and the monomer corresponding to it used suitably are demonstrated.

[Structural Unit / Monomer Having Acid Leaving Group]
The resist copolymer preferably has an acid leaving group. The “acid-leaving group” is a group having a bond that is cleaved by an acid, and a part or all of the acid-leaving group is eliminated from the main chain of the copolymer by cleavage of the bond. .
When used as a resist composition, a copolymer having a structural unit having an acid-eliminable group is soluble in an alkali by an acid, and has an effect of enabling formation of a resist pattern.
The proportion of the structural unit having an acid leaving group is preferably 20 mol% or more of the total structural units constituting the copolymer from the viewpoint of sensitivity and resolution. Moreover, 60 mol% or less is preferable from the point of the adhesiveness to a board | substrate etc., 55 mol% or less is more preferable, and 50 mol% or less is further more preferable.

Examples of the structural unit having an acid leaving group include a structural unit derived from a monomer having a known acid leaving group.
As the monomer having an acid leaving group, for example, a (meth) acryl having an alicyclic hydrocarbon group having 6 to 20 carbon atoms and a group capable of leaving by the action of an acid. Acid ester etc. are mentioned. The alicyclic hydrocarbon group may be directly bonded to an oxygen atom constituting an ester bond of (meth) acrylic acid ester, or may be bonded via a linking group such as an alkylene group.

  The (meth) acrylic acid ester has an alicyclic hydrocarbon group having 6 to 20 carbon atoms, and a tertiary carbon atom at the bonding site with the oxygen atom constituting the ester bond of the (meth) acrylic acid ester. A (meth) acrylic acid ester having an alicyclic group or an alicyclic hydrocarbon group having 6 to 20 carbon atoms and a -COOR group (R may have a substituent) on the alicyclic hydrocarbon group. (Meth) acrylic acid ester in which a tertiary hydrocarbon group, a tetrahydrofuranyl group, a tetrahydropyranyl group, or an oxepanyl group is bonded directly or via a linking group is included.

In the case of producing a resist composition applied to a pattern forming method in which exposure is performed with light having a wavelength of 250 nm or less, preferred examples of the monomer having an acid leaving group include, for example, 2-methyl-2-adamantyl ( (Meth) acrylate, 2-ethyl-2-adamantyl (meth) acrylate, 2-isopropyl-2-adamantyl (meth) acrylate, 1- (1′-adamantyl) -1-methylethyl (meth) acrylate, 1-methylcyclohexyl (Meth) acrylate, 1-ethylcyclohexyl (meth) acrylate, 1-methylcyclopentyl (meth) acrylate, 1-ethylcyclopentyl (meth) acrylate and the like can be mentioned.
As the monomer having an acid leaving group, one type may be used alone, or two or more types may be used in combination.

[Constitutional unit / monomer having a lactone skeleton]
When applied to a pattern forming method in which exposure is performed with light having a wavelength of 250 nm or less, the resist copolymer preferably further includes a structural unit having a lactone skeleton.
Examples of the lactone skeleton include a lactone skeleton having about 4 to 20 members. The lactone skeleton may be a monocycle having only a lactone ring, or an aliphatic or aromatic carbocyclic or heterocyclic ring may be condensed with the lactone ring.
The proportion of the structural unit having a lactone skeleton is preferably 20% by mole or more, more preferably 35% by mole or more, of all the structural units (100% by mole) from the viewpoint of adhesion to a substrate or the like. Moreover, 60 mol% or less is preferable from the point of sensitivity and resolution, and 55 mol% or less is more preferable.

Examples of the structural unit having a lactone skeleton include structural units derived from a monomer having a lactone skeleton.
As a monomer having a lactone skeleton, a (meth) acrylic acid ester having a substituted or unsubstituted δ-valerolactone ring, a substituted or unsubstituted γ-butyrolactone ring is used because of its excellent adhesion to a substrate or the like. Preferably, at least one selected from the group consisting of monomers having it is preferred, and monomers having an unsubstituted γ-butyrolactone ring are particularly preferred.

Specific examples of the monomer having a lactone skeleton include β- (meth) acryloyloxy-β-methyl-δ-valerolactone, 4,4-dimethyl-2-methylene-γ-butyrolactone, β- (meth) acryloyl. Oxy-γ-butyrolactone, β- (meth) acryloyloxy-β-methyl-γ-butyrolactone, α- (meth) acryloyloxy-γ-butyrolactone, 2- (1- (meth) acryloyloxy) ethyl-4-butanolide , (Meth) acrylic acid pantoyl lactone, 5- (meth) acryloyloxy-2,6-norbornanecarbolactone, 8-methacryloxy-4-oxatricyclo [5.2.1.0 ^2,6 ] decane-3 -One, 9-methacryloxy-4-oxatricyclo [5.2.1.0 ^2,6 ] decan-3-one and the like. Examples of the monomer having a similar structure include methacryloyloxysuccinic anhydride.
Monomers having a lactone skeleton may be used alone or in combination of two or more.

[Structural unit having hydrophilic group]
The resist copolymer may further have a structural unit having a hydrophilic group. The “hydrophilic group” is at least one of —C (CF ₃ ) ₂ —OH, a hydroxy group, a cyano group, a methoxy group, a carboxy group, and an amino group.
The proportion of the structural unit having a hydrophilic group is preferably 5 to 40 mol% and more preferably 10 to 35 mol% in the total structural units (100 mol%) from the viewpoint of the resist pattern rectangularity.

Examples of the structural unit having a hydrophilic group include a structural unit derived from a monomer having a hydrophilic group.
As the monomer having a hydrophilic group, for example, a (meth) acrylic acid ester having a terminal hydroxy group, a derivative having a substituent such as an alkyl group, a hydroxy group, or a carboxy group on the hydrophilic group of the monomer, Monomers having a cyclic hydrocarbon group (cyclohexyl (meth) acrylate, 1-isobornyl (meth) acrylate, adamantyl (meth) acrylate), tricyclodecanyl (meth) acrylate, dimethacrylate (meth) acrylate Cyclopentyl, 2-methyl-2-adamantyl (meth) acrylate, 2-ethyl-2-adamantyl (meth) acrylate, etc.) having a hydrophilic group such as a hydroxy group or a carboxy group as a substituent. Can be mentioned.

Specific examples of the monomer having a hydrophilic group include (meth) acrylic acid, 2-hydroxyethyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, and 2-hydroxy- (meth) acrylate. -Propyl, 4-hydroxybutyl (meth) acrylate, 3-hydroxyadamantyl (meth) acrylate, 2- or 3-cyano-5-norbornyl (meth) acrylate, 2-cyanomethyl-2-adamantyl (meth) acrylate, etc. Is mentioned. From the viewpoint of adhesion to a substrate or the like, 3-hydroxyadamantyl (meth) acrylate, 2- or 3-cyano-5-norbornyl (meth) acrylate, 2-cyanomethyl-2-adamantyl (meth) acrylate and the like are preferable.
The monomer which has a hydrophilic group may be used individually by 1 type, and may be used in combination of 2 or more type.

[Structural unit having a structure that absorbs radiation]
When the copolymer of the present invention is a copolymer for an antireflection film, it needs to include a molecular structure that absorbs radiation irradiated in the semiconductor lithography process.
The structure that absorbs radiation differs depending on the wavelength of the radiation used. For example, a naphthalene skeleton or an anthracene skeleton is preferable for KrF excimer laser light, and a benzene skeleton is preferable for ArF excimer laser.
Examples of monomers that give structural units having these molecular structures include styrenes such as styrene, α-methylstyrene, p-methylstyrene, p-hydroxystyrene, m-hydroxystyrene, and derivatives thereof, substituted or unsubstituted Aromatic-containing esters having an ethylenic double bond such as phenyl (meth) acrylate, substituted or unsubstituted naphthalene (meth) acrylate, substituted or unsubstituted anthracenemethyl (meth) acrylate, etc. .
As for the ratio of the structural unit which has the molecular structure which absorbs a radiation, 10-100 mol% is preferable among all the structural units (100 mol%) of a copolymer.

<Polymerization method>
Examples of the polymerization method for producing a copolymer for semiconductor lithography include known polymerization methods such as a bulk polymerization method, a solution polymerization method, a suspension polymerization method, and an emulsion polymerization method. Among these, the solution polymerization method is preferable in order not to decrease the light transmittance, because the step of removing the monomer remaining after the completion of the polymerization reaction can be easily performed, and the molecular weight of the copolymer can be relatively lowered. .
The solution polymerization method is, for example, a method in which a solvent and all monomers are charged into a reactor and reacted (hereinafter referred to as a batch method), and all monomers used for synthesizing a polymer are dropped. The copolymer can be synthesized by a method of supplying to the solvent in the reactor (hereinafter referred to as a total dropping method) and a partial dropping method described below. In particular, the following partial dropping method is preferable in that a uniform copolymer is easily formed over time.
The batch method and the total dropping method described above can be performed using known methods.

<Partial dripping method>
In this method, a first solution containing a monomer with a first composition is charged in a reactor in advance, and after heating the reactor to a predetermined polymerization temperature, One or more dropping solutions containing the body are dropped.
If a monomer having the same monomer composition as the dropping solution is dropped uniformly over a certain period of time without previously charging the monomer into the reactor, the monomer having a slow monomer consumption rate in the copolymerization reaction is In the latter stage of polymerization, it is incorporated into the copolymer at a ratio higher than the desired composition ratio, resulting in variations in monomer composition and chain structure.
Therefore, in this method, two or more types of solutions are prepared, and in the first solution prepared in advance in the reactor, the composition ratio (content ratio) of the monomer with a slow monomer consumption rate is set to the polymerization reaction. It is preferable to make it larger than the composition ratio of the monomer in the total amount of all the solutions used in the above.

On the other hand, a monomer having a high monomer consumption rate (that is, polymerization rate) in the copolymerization reaction is incorporated into the copolymer in a proportion higher than the desired composition ratio in the first stage of polymerization, and the monomer composition and chain This causes structural variations.
Therefore, in this method, two or more types of solutions are prepared, and in the dropping solution that is dropped first, the monomer composition ratio of the monomer having a high monomer consumption rate is used for all polymerization reactions. It is preferable to make it smaller than the composition ratio of the monomer in the total amount of the solution.
The polymerization initiator may be contained in a dropping solution containing a monomer, or may be dropped into the reactor separately from the monomer.
The dropping speed may be constant until the dropping is completed, or may be changed in multiple stages according to the monomer consumption. The dripping may be performed continuously or intermittently.
The polymerization temperature is preferably 50 to 150 ° C.

Examples of the solvent for the first solution and the dropping solution include the following.
Ethers: chain ethers (eg, diethyl ether, propylene glycol monomethyl ether (hereinafter referred to as “PGME”), etc.), cyclic ethers (eg, tetrahydrofuran (hereinafter referred to as “THF”), 1,4-dioxane, etc. .)etc.
Esters: methyl acetate, ethyl acetate, butyl acetate, ethyl lactate, butyl lactate, propylene glycol monomethyl ether acetate (hereinafter referred to as “PGMEA”), γ-butyrolactone, and the like.
Ketones: acetone, methyl ethyl ketone (hereinafter referred to as “MEK”), methyl isobutyl ketone (hereinafter referred to as “MIBK”), cyclohexanone, and the like.
Amides: N, N-dimethylacetamide, N, N-dimethylformamide (hereinafter referred to as DMF) and the like.
Sulfoxides: dimethyl sulfoxide and the like.
Aromatic hydrocarbons: benzene, toluene, xylene and the like.
Aliphatic hydrocarbon: hexane and the like.
Alicyclic hydrocarbons: cyclohexane and the like.
A solvent may be used individually by 1 type and may use 2 or more types together.

  As the polymerization initiator, those that generate radicals efficiently by heat are preferable. For example, an azo compound (2,2′-azobisisobutyronitrile, dimethyl-2,2′-azobisisobutyrate, 2,2′-azobis [2- (2-imidazolin-2-yl) propane] Etc.), organic peroxides (2,5-dimethyl-2,5-bis (tert-butylperoxy) hexane, di (4-tert-butylcyclohexyl) peroxydicarbonate, etc.) and the like.

<Purification method>
The copolymer solution produced by solution polymerization is adjusted to an appropriate solution viscosity with a good solvent such as 1,4-dioxane, acetone, THF, MEK, MIBK, γ-butyrolactone, PGMEA, PGME, and DMF, if necessary. After dilution, the copolymer is precipitated by dropping into a large amount of poor solvent such as methanol, water, hexane, heptane or the like. This process is generally called reprecipitation and is very effective for removing unreacted monomers, polymerization initiators, and the like remaining in the polymerization solution. If these unreacted substances remain as they are, there is a possibility of adversely affecting the resist performance. Therefore, it is preferable to remove them as much as possible. The reprecipitation process may be unnecessary depending on circumstances. Thereafter, the precipitate is filtered off and sufficiently dried to obtain the copolymer of the present invention. Moreover, after filtering off, it can also be used with a wet powder, without drying.
Further, the produced copolymer solution can be used as a resist composition as it is or after being diluted with an appropriate solvent. At that time, additives such as a storage stabilizer may be appropriately added.

<Evaluation method>
The copolymer evaluation method using the copolymer composition analyzer in the present embodiment includes the following steps.
(1) A measurement process (performed in the NMR measurement unit 50) in which a copolymer for lithography is dissolved in a solvent and NMR measurement of the copolymer is performed;
(2) Waveform processing step (performed in the waveform processing unit 11) for performing Fourier transform and data processing of the FID signal of the copolymer obtained in the measurement step (1);
(3) Principal component analysis that performs principal component analysis of quantitative use information of NMR spectrum data output from the waveform processing step (2) for each sample and calculates a principal component score of each selected principal component Step (performed in the principal component analysis unit 12);
(4) The principal component of each principal component output from the step (3) in the principal component space composed of the principal component axes of the number of types of monomers, that is, the number of types of monomers as the number of dimensions. The position on the different coordinate axis (principal component axis) that goes directly to the component score is expressed as a coordinate value, and the coordinate point that is the position in the principal component space of each sample is the coordinate value (principal component score) of each coordinate axis (principal component axis) ), And a numerical value conversion step (performed in the numerical value conversion unit 13) that calculates an evaluation distance that is a distance between the comparison space that passes through all the coordinate points represented by the main component score of the homopolymer and the coordinate points represented by each sample. ;
(5) Based on the evaluation distance between the comparison space calculated through the steps (1) to (4) and passing through all the coordinate points represented by the main component scores of the homopolymer and the points represented by each sample, A characteristic evaluation step for evaluating the lithography characteristics of the composition containing the polymer (performed in the characteristic evaluation unit 14)

The apparatus as the NMR measurement part 50 used for NMR measurement should just use a commercial item, and is not specifically limited. However, from the viewpoint of high chemical shift resolution, it is preferable to use an NMR apparatus having a magnetic field strength of 7 Tesla (300 MHz as the frequency of ¹ H nucleus) or more.
The observation nucleus in the NMR measurement may be appropriately selected according to the type of the copolymer (P), but ¹ H, ¹³ C, ¹⁹ F, and ²⁹ Si are preferable from the viewpoint of high natural abundance ratio and sensitivity.
The diameter of the sample tube used for the NMR measurement may be appropriately selected according to the type of the copolymer (P). However, when ¹ H or ¹⁹ F is selected as the observation nucleus, the natural abundance ratio is high. 3 mmφ or more is preferable, and 5 mmφ or more is more preferable. Further, when ¹³ C or ²⁹ Si is selected as the observation nucleus, it is preferably 5 mmφ or more, more preferably 10 mmφ or more from the viewpoint that a higher sensitivity signal intensity can be obtained.

The concentration of the sample in the deuterated solvent of the copolymer used for NMR measurement is not particularly limited, but is preferably 1% by mass or more, more preferably 5% by mass or more from the viewpoint of obtaining a more sensitive signal intensity. More preferred is 10% by mass or more.
Moreover, from the point which suppresses the influence of the relaxation time by the viscosity of a sample solution, 50 mass% or less is preferable, 30 mass% or less is more preferable, and 20 mass% or less is further more preferable.

The deuterated solvent used in the NMR measurement is not particularly limited as long as the copolymer can be dissolved. For example, deuterated chloroform (CDCl ₃ ), deuterated dimethyl sulfoxide (DMSO-d ₆ ), deuterated water ( D ₂ O), deuterated methanol (CH ₃ OD or CD ₃ OD), deuterated hexafluoroisopropanol (HFIP-d ₂ ), and the like. Further, tetramethylsilane (TMS) or CFCl ₃ may be added as a reference substance for chemical shift.

The sample temperature at the time of NMR measurement is not particularly limited as long as it is not higher than the boiling point of the sample solvent or does not cause decomposition or alteration of the copolymer. It is preferable that the temperature is as high as possible.
The number of data integration at the time of NMR measurement is not particularly limited, and may be appropriately selected according to the type of observation nucleus to be measured. However, when ¹ H or ¹⁹ F is selected as the observation nucleus, the natural abundance ratio is high. Therefore, 4 times or more is preferable, and 16 times or more is more preferable. Further, when ¹³ C or ²⁹ Si is selected as the observation nucleus, it is preferably 1500 times or more and more preferably 3000 times or more from the viewpoint that a higher sensitivity signal intensity can be obtained. Here, the integration at the time of NMR measurement means that an NMR signal is taken a plurality of times, and the plurality of signals are superimposed (or integrated or added), and the superimposed signal is used as a final FID signal of the observation result of the sample. It means that.

In the waveform processing step, the waveform processing unit 11 performs Fourier transform of the FID signal obtained by NMR measurement as described above, and has information on chemical shift (frequency component) and signal intensity (spectral intensity). Generate data.
At this time, by setting the BF (Broadening factor) corresponding to the type of observation nucleus to be measured (measured in advance in an experiment, the broadening factor corresponding to each observation nucleus is set). Since the spectral resolution of the observation nucleus can be improved, the measurement accuracy can be improved.
In addition, the waveform processing unit 11 performs phase adjustment of the Fourier-transformed chemical shift and the NMR spectrum signal composed of the waveform (correction processing for making each NMR spectrum signal symmetrical) and baseline processing (base of the NMR spectrum signal). Correct the line so that it is parallel to the frequency axis), set the reference chemical shift value, and integrate the signal intensity for each frequency range and the frequency range divided by the predetermined range. Quantitative usage information G (determinant) of NMR spectrum data consisting of values is output. Here, as the range of the chemical shift used for generating the NMR spectrum signal, the range including the observation nuclei of the respective structural units constituting the copolymer to be evaluated is used. That is, the waveform processing unit 11 extracts from the NMR spectrum input from the NMR measurement unit 50 an NMR spectrum only in a frequency range including the wavelengths of observation nuclei in all monomers constituting the copolymer to be evaluated. The NMR spectrum signal is generated.

In the waveform processing step of the waveform processing unit 11, in the division and integration of the NMR spectrum of the present embodiment, the frequency range for integrating the spectral intensity of the chemical shift after performing the Fourier transform, that is, the chemical shift is divided. Frequency spacing is important.
That is, the waveform processing unit 11 sequentially reads each of the NMR data of the m types of copolymer and homopolymer samples from the NMR data storage unit 15 according to the sample identification information or the monomer identification information, As NMR spectrum data of each sample of the homopolymer, data having an integral value of the spectrum intensity for each frequency range of chemical shift is obtained.
For example, the waveform processing unit 11 sets the chemical shift (frequency range) at regular intervals for the k-th sample (k is an integer of 1 to m) among m types of copolymer and homopolymer samples. The frequency range is divided equally (p is an integer), and the g-th integrated value of the divided frequency range is defined as f _kg . As described above, the waveform processing unit 11 performs processing for generating NMR spectrum data of each of the copolymer and the homopolymer sample from the NMR spectra of the m types of the copolymer and the homopolymer sample.
Here, the homopolymer is a polymer composed of monomers of the same type among the monomers constituting the copolymer to be evaluated. For this reason, when the copolymer to be evaluated is composed of n types of monomers, the homopolymer has n types, so that m> n.
Further, the waveform processing unit 11 adds the integral value of the spectrum intensity (signal intensity) in the frequency range obtained by dividing the chemical shift for each sample of the copolymer and the homopolymer in all the divided frequency ranges. Assuming that the sum of the addition values is 100, the integration value in each frequency range is normalized as shown in the following equation.
f _k1 + f _k2 +... f _kg +... + f _kp = 100

Next, the waveform processing unit 11 adds the standardized integral values of the g-th frequency range of all m types of samples, divides the addition result by the number of types m, and all the m types of g-th frequency ranges. The average value f _g-ave is obtained from the following equation as the average value of the integrated values of:
_fg-ave = ( _f1g + _f2g + ... _fkg + ... + _fmg ) / m
Similarly, the waveform processing unit 11 calculates the above-described average value in all m types for all frequency ranges (divided spectrums) equally divided by p, and then determines the frequency range of the NMR spectrum for the integrated value of the i-th sample. Every time, the average value f _g-ave of the frequency range which is the division range of the corresponding chemical shift is subtracted from the integrated value of the normalized spectral intensity, and the following formula is obtained as a standardized integrated value b _kg of the subtracted result. Ask for.
_{b kg = f kg -f g-} ave

And the waveform process part 11 makes the spectrum intensity | strength for every division area of the measured frequency of kth sample the NMR spectrum data represented by the vector of following Formula.
x _k = (b _k1 , b _k2 ,..., b _kg ,..., b _kp )
And the waveform process part 11 puts together the spectrum intensity about all m types of samples, and represents with the matrix G of the following (1) Formula. The matrix G (m rows and p columns) shown in the equation (1) is a chemical shift and a signal intensity (after integration) that are the basis for generating the explanatory variables. As will be described later, the matrix G is subjected to principal component analysis to create a matrix T of explanatory variables.

When the matrix G is supplied from the waveform processing unit 11, the principal component analysis unit 12 generates a transposed matrix G ^T (p rows and m columns) of the matrix G.
The principal component analysis unit 12, with respect to the matrix G, multiplied by the transposed matrix G ^T determined from the left, obtaining the sum of products matrix G ^{T G.}
Next, the principal component analysis unit 12 obtains the eigenvector V of the obtained product-sum matrix G ^T G by the following relational expression.
G ^T GV = Δ ² V
Here, the obtained eigenvector V is represented by the following equation (2), and the eigenvalue Δ ² (that is, λ) is represented by the following (3).

Further, V in the formula (2) has the following relationship.
{(a ₁₁ ) ² + (a ₂₁ ) ² + ... + (a _p1 ) ² } ^1/2 = {(a ₁₂ ) ² + (a ₂₂ ) ² + ... + (a _p2 ) ² } ^1/2 = ... = {(a _1p ) ² + (a _2p ) ² +... + (A _pp ) ² } ^1/2 = 1.
Further, in (3) of the ^{_{Δ 2, λ 1, λ 2}} , ···, λ p is the eigenvalues of the product sum matrix ^{G T} G, a _{λ 1> λ 2>···>} λ p.
For example, in order to obtain the eigenvalue λ ₁ from the relational expression of G ^T GV = Δ ² V, when solving for λ using the theorem for obtaining the eigenvalue of the following equation, a maximum of p solutions are obtained. The largest λ in the solution is λ ₁ .
det (G ^T G-λI) = 0
Note that det (G ^T G-λI) is a determinant of (G ^T G-λI), and I is a unit matrix of p rows and p columns.

Here, the eigenvalue λ ₂ is the second largest λ of the solutions λ, and can be obtained up to λ _{p in the same} manner.
Then, the principal component analysis unit 12 substitutes the eigenvalues λ ₁ , λ ₂ ,..., Λ _p into λ of the relational expression of G ^T GV = λV, solves the expression, and obtains the eigenvector V.
Next, the principal component analysis unit 12 multiplies the obtained eigenvector V by a matrix G (a matrix in which spectral intensities for all n types of samples are collected) from the right as shown below, thereby obtaining a principal component score. A matrix T representing (score) can be obtained.
GV = T
The matrix T is a matrix having m rows and a maximum of p columns, and is represented by the following equation (4).

The first column of the matrix T is the principal component score of the first principal component PC1 in each of the m types of samples, the second column is the principal component score of the second principal component PC2, and so on. The main component score of PCn can be obtained. For example, t _k1 that is the first principal component score of the k-th sample is expressed by the following equation.
t _k1 = b _k1 a ₁₁ + b _k2 a ₁₂ +... + b _kp a _1p
The principal component analysis unit 12 writes the obtained principal component score of each sample into the principal component data storage unit 16 together with the sample identification information or the monomer identification information, and stores them.

Next, the numerical value conversion process will be described in detail. In the following description, for the sake of simplicity, a case where there are two types of structural unit monomers (n = 2) will be described as an example. In particular, the number of types of monomers is not limited to n = 2. There is no limitation on the number n of structural units indicating the number of types of monomers.
FIG. 3 is a diagram illustrating a two-dimensional principal component space in which the horizontal axis is the first principal component axis (PC1) and the vertical axis is the second principal component axis (PC2). That is, a two-dimensional space, which is a principal component space in which the principal component axis PC1 and the principal component axis PC2 are configured to be orthogonal, is shown.
The coordinate value of the homopolymer composed of the monomer A-1 and the monomer A-2 is one dimension less than the principal component space as a comparison space Q that is a space including the coordinate values of each other. A space (line segment) is formed.

Here, the numerical value conversion unit 13 is a first principal component axis PC1 of each of the copolymer S composed of two structural units and the homopolymer samples A-1 and A-2 composed of a single structural unit. And the principal component score of the second principal component axis PC2 are read from the principal component data storage unit 16 by using the sample identification information or the monomer identification information, and the principal component scores of these principal component axes are coordinated. As a value, a coordinate point in the principal component space consisting of the respective principal component scores is determined as follows. Similarly, the coordinate points of the sample S of the copolymer to be evaluated are determined as follows.
P (A-1) = (PC1 (A-1), PC2 (A-1))
P (A-2) = (PC1 (A-2), PC2 (A-2))
P (S) = (PC1 (S), PC2 (S))

  Since Samples A-1 and A-2 are homopolymers, a single constituent unit is completely continuously bonded in the composition of the polymer, that is, the same type of monomer has another type of monomer. It is composed by connecting continuously without including. A one-dimensional space (line segment as comparison space Q) passing through all two points of coordinate points P (A-1) and P (A-2), that is, coordinate point P (A-1) and coordinate point P (A- 2) is a line segment with the highest continuity of the arrangement of the monomers because the same monomer is continuously connected and arranged as the constitutional unit. is there. The evaluation distance L (S) from this line segment indicates the randomness of the arrangement of the monomers in the chain structure in the copolymer.

For example, the numerical value conversion unit 13 determines numerical values a, b, and c as shown in the following equation.
a = PC2 (A-2) -PC2 (A-1)
b = PC1 (A-1) -PC1 (A-2)
c = -PC1 (A-1) * (PC2 (A-2) -PC2 (A-1))-PC2 (A-1) * (PC1 (A-1) -PC1 (A-2))
Here, the numerical value a indicates the difference in the second principal component score between the sample A-2 and the sample A-2 on the second principal component axis PC2. The numerical value b shows the difference of the first principal component score between the sample A-2 and the sample A-2 on the first principal component axis PC1. The numerical value c is a negative value obtained by multiplying the numerical value a by the first principal component score of the sample A-1, and a negative value obtained by multiplying the numerical value b by the second principal component score of the sample A-1. It is the value which added the numerical value of.

Then, the numerical value conversion unit 13 includes a straight line (one-dimensional space) of the comparison space Q passing through all the coordinate points P (A-1) and P (A-2) of the samples A-1 and A-2. The evaluation distance L (S) with the coordinate point P (SPC1, SPC2) of the sample S to be evaluated is calculated by the following equation. Here, SPC1 is the first principal component score of sample S, and SPC2 is the second principal component score.
L = | a × SPC1 + b × SPC2 + c | / (a ² + b ² ) ^1/2
The numerical value conversion unit 13 calculates the evaluation distance L (S) as described above. Here, a point representing the polymer sample S to be evaluated and the coordinate points P (A-1) and P (A-2) of the homopolymer samples A-1 and A-2 are all passed. The greater the evaluation distance L (S) from the straight line, the higher the randomness of the copolymer chain.
That is, each main component in the present embodiment is a component showing randomness in the monomer arrangement in the copolymer. As a result, the evaluation distance L (S) qualitatively determines the length of continuous arrangement of the same monomer in the chain structure of the copolymer (the number of the same type of monomer continuously arranged). Can be evaluated.

As a result, the evaluation distance from the space including the coordinate point of the homopolymer is such that the same type of monomer is adjacently arranged and in a blocked state, and a different type of monomer is adjacent. It can be used as a reference for qualitatively determining the difference from the arranged random state.
Therefore, the characteristic evaluation unit 14 arranges different monomers in the copolymer chain adjacent to each other as the evaluation distance L (S) between the sample of the copolymer to be evaluated and the space made of the homopolymer is larger. It is determined that the sequence sequence is highly random.

For example, if the distance threshold obtained from the past experiment is set inside and the evaluation distance L (S) calculated by the numerical value converter 13 is less than the set distance threshold, the characteristic evaluation unit 14 An NG signal indicating that the copolymer is unsuitable as a copolymer is output. On the other hand, if the evaluation distance L (S) is equal to or greater than the distance threshold, an OK signal indicating that the copolymer is suitable for a resist copolymer is output. It may be configured.
In addition, the characteristic evaluation unit 14 shows the numerical value of the lithography characteristic consisting of the solubility and the sensitivity to light for each of a plurality of length ranges, and the evaluation distance L (S) from the past experiment. You may comprise so that the numerical value of the lithography characteristic at the time of adjusting a resist composition using this resist polymer from distance L (S) may be output.

Moreover, the resist composition prepared with the resist copolymer having high randomness effectively improves the solubility in a solvent during development, as shown in an application example described later. Moreover, in the resist composition containing the copolymer, the sensitivity to light during lithography is improved.
The reason why the effect of improving the solubility and sensitivity to light can be obtained is as follows.
In general, the amount of each monomer used in the synthesis of the copolymer is determined according to the target value of the monomer composition to be obtained, and the average monomer composition in the copolymer after synthesis is the target value. The polymerization conditions and the like are set so as to be close to the monomer composition.
However, in many cases, since the copolymerization reactivity ratios of the monomers to be copolymerized are different from each other, the copolymer composition of the resulting copolymer is different from that of the copolymer obtained without random copolymerization. In the arrangement of the monomers in the chain, a block of the same type of monomer is formed, resulting in bias.

In addition, according to the knowledge of the present inventors, a difference occurs in the monomer composition in the copolymer obtained depending on the reaction time (polymerization rate). In particular, in the early and late stages of the polymerization reaction, the monomer composition is greatly different from the target value, and a copolymer containing a large number of polymerization chains in which the same structural units are connected tends to be produced.
On the other hand, since the solvent used for the lithography composition used for semiconductors has poor solubility in homopolymers, it is presumed that the polymerization chain in which the same structural units are linked deteriorates the solubility in the solvent.
Further, when the randomness of the chain structure is high, it is presumed that the structural units are more uniformly distributed in each copolymer chain. For this reason, it is considered that high lithographic properties can be obtained when a resist copolymer is prepared as a resist composition.

For the above reasons, the evaluation method according to the present embodiment is characterized by simply evaluating the randomness of the resist copolymer, so that the characteristics of the resist composition including the resist copolymer can be actually measured. Can be evaluated without adjusting.
That is, in this embodiment, when evaluating the composition of a copolymer for resist or a copolymer for lithography, the copolymer is treated as a resist by simply estimating the randomness of the chain structure of these copolymers. Lithographic properties when used as a composition for a composition can be evaluated without actually producing this resist composition, and without actually undergoing a lithography process, and the resolution of light in exposure as a resist, It is an object of the present invention to provide a method capable of strictly evaluating the uniformity of dissolution performance in a solvent during development.
Therefore, this embodiment can easily evaluate the randomness of the arrangement of the monomers in the chain structure of the copolymer, and obtain a correlation between the randomness and the characteristics of the composition using the copolymer. By adjusting the composition, it is possible to evaluate the adjusted composition without adjusting the composition with the copolymer and evaluating the characteristics of the adjusted composition, as in the prior art.
In addition, since the present embodiment is evaluated using the NMR spectrum obtained by NMR measurement, the temperature of the heat treatment is used for the determination of the monomer in the polymer or the estimation of the chain distribution, as in the past. There is no measurement error such as the difference in the thermal decomposition efficiency of the sample due to or the inability to quantitatively obtain the thermal decomposition product reflecting the structural unit, so there is no need to prepare a large number of samples for correction processing etc. The composition can be easily evaluated.

  Hereinafter, although the application example of this embodiment is demonstrated concretely, this embodiment is not limited to these. In each application example and comparative example, “part” means “part by mass (unit mol)” unless otherwise specified. The measurement method and evaluation method used the following methods.

(Measurement of mass average molecular weight)
The mass average molecular weight (Mw) of the copolymer was determined in terms of polystyrene by GPC under the following conditions (GPC (Gel Permeation Chromatography) conditions).
[GPC conditions]
Equipment: Tosoh Corporation, Tosoh High Speed GPC Equipment HLC-8220GPC (trade name),
Separation column: manufactured by Showa Denko, Shodex GPC K-805L (trade name) connected in series,
Measurement temperature: 40 ° C.
Eluent: THF,
Sample: A solution in which about 20 mg of the copolymer was dissolved in 5 mL (milliliter) of THF and filtered through a 0.5 μm membrane filter.
Flow rate: 1 mL / min,
Injection volume: 0.1 mL,
Detector: differential refractometer.

Calibration curve I: About 20 mg of standard polystyrene was dissolved in 5 mL of THF, and the solution was filtered through a 0.5 μm membrane filter and injected into a separation column under the above conditions, and the relationship between elution time and molecular weight was determined. As the standard polystyrene, the following standard polystyrene manufactured by Tosoh Corporation (both trade names) were used.
F-80 (Mw = 706,000),
F-20 (Mw = 190,000),
F-4 (Mw = 37,900),
F-1 (Mw = 10,200),
A-2500 (Mw = 2,630),
A-500 (mixture of Mw = 682, 578, 474, 370, 260).

(Measurement of average monomer composition of copolymer)
About 5 parts by mass of the copolymer was dissolved in about 95 parts by mass of deuterated dimethyl sulfoxide to prepare a sample solution. This sample solution was put into an NMR tube and analyzed using ¹ H-NMR (manufactured by JEOL, resonance frequency: 270 MHz). The average monomer composition of the copolymer was calculated from the integrated intensity ratio of signals derived from each structural unit.

(Evaluation of solubility of copolymer)
20 parts of the copolymer and 80 parts of PGMEA (Propylene Glycol Monomethyl Ether Acetate) were mixed, stirred while maintaining at 25 ° C., and judged to be completely dissolved, and the time until complete dissolution was measured.

(Evaluation of resist composition sensitivity)
The resist composition was spin-coated on a 6-inch silicon wafer and pre-baked (PAB) at 120 ° C. for 60 seconds on a hot plate to form a resist film having a thickness of 300 nm.
Then, using an ArF excimer laser exposure apparatus (product name: VUVES-4500, manufactured by RISOTEC JAPAN), 18 shots having an area of 10 mm × 10 mm were exposed while changing the exposure amount.
Next, after post-baking (PEB) at 110 ° C. for 60 seconds, 2.38% water was used at 23.5 ° C. using a resist development analyzer (product name: RDA-806, manufactured by RISOTEC JAPAN). Development was performed with an aqueous tetramethylammonium oxide solution for 65 seconds. For each exposure amount of the resist film, the change with time in the resist film thickness during development was measured.

Based on the data of change in resist film thickness over time, the logarithm of the exposure amount (unit: mJ / cm ² ) and the ratio of the remaining film thickness at the time of development for 30 seconds with respect to the initial film thickness (unit:%). , Hereinafter referred to as the residual film ratio) was plotted, and an exposure amount-residual film ratio curve was prepared. Based on this curve, the value of the necessary exposure amount (Eth) for obtaining a remaining film rate of 0% was determined. That is, the exposure amount (mJ / cm ² ) at the point where the exposure amount-residual film rate curve intersects a straight line with a residual film rate of 0% was determined as Eth. The value of Eth represents sensitivity, and the smaller the value, the higher the sensitivity.

<Synthesis Example 1: Homopolymer A-1>
In this synthesis example, the following monomer (m-1) was polymerized alone.

  First, in a 25 mL Schlenk flask, 3.40 parts of monomer (m-1) and 1.38 parts of dimethyl-2,2'-azobisisobutyrate (manufactured by Wako Pure Chemical Industries, Ltd., V601 ( (Trade name)) was added together with 13.6 parts of ethyl lactate, and then nitrogen was blown into the solution at 200 mL / min for 1 minute. The flask was then placed on a 80 ° C. hot water bath and stirred for 3 hours with stirring.

  Next, the obtained reaction solution was added dropwise to about 20 times amount of methanol with stirring to obtain a white precipitate (homopolymer A-1). And the precipitate after washing | cleaning was separated by filtration, and copolymer wet powder was obtained. The copolymer wet powder was dried under reduced pressure at 40 ° C. for about 40 hours to obtain a white powder (2.0 g).

<Synthesis Examples 2-3: Homopolymers A-2 and A-3>
In this synthesis example, the same procedure as in Synthesis example 1 was carried out except that the monomer used was changed from the above (m-1) to the following (m-2) and (m-3). Polymer A-2 (2.4 g) and A-3 (1.8 g) were obtained.

<Synthesis Examples 4 to 5: Homopolymers A-4 and A-5>
In this synthesis example, the monomer used was changed from the above (m-1) to the following (m-4) and (m-5) respectively, and the solvent was changed from 13.6 g of ethyl lactate to ethyl lactate and PGMEA. The homopolymers A-4 (2.7 g) and A-5 (1.4 g) were prepared in the same manner as in Synthesis Example 1 except that the mixture was changed to a mixture of (ethyl lactate / PGMEA = 50/50 mass ratio). Obtained.

<Synthesis Example 6: Homopolymer A-6>
In this synthesis example, the monomer used was changed from (m-1) to the following (m-6), and the solvent was changed from 13.6 g of ethyl lactate to dimethylformamide. By operation, a homopolymer A-6 (2.7 g) was obtained.

<Synthesis Example 7: Copolymer B-1>
[Production of copolymer]
In this synthesis example, monomers (m-1), (m-2), and (m-3) were partially polymerized by a dropping method. The molar ratio of the total amount of each monomer used is (m-1) :( m-2) :( m-3) = 39.0: 41.3: 19.7.

In a flask equipped with a nitrogen inlet, a stirrer, a condenser, a dropping funnel, and a thermometer, in a nitrogen atmosphere, 79.0 parts of ethyl lactate and 2.72 parts of monomer (m-1), a single amount 4.90 parts of body (m-2) and 2.02 parts of monomer (m-3) were added. The flask was placed in a hot water bath, and the temperature of the hot water bath was raised to 80 ° C. while stirring the flask.
Thereafter, from a dropping device containing 3.6 parts of ethyl lactate and 1.196 parts of dimethyl-2,2′-azobisisobutyrate (manufactured by Wako Pure Chemical Industries, Ltd., V601 (trade name)) at a constant speed for 15 minutes. While dropping into the flask, 23.80 parts of monomer (m-1), 27.44 parts of monomer (m-2), 16.52 parts of monomer (m-3), lactic acid From a dropping apparatus containing 98.06 parts of ethyl and 0.643 parts of dimethyl-2,2′-azobisisobutyrate (above, V601 (trade name)) was dropped into the flask at a constant rate over 4 hours. . Furthermore, the temperature of 80 degreeC was hold | maintained for 3 hours.

  Next, the polymerization reaction solution in the flask was dropped into the mixture while stirring a mixed solvent of methanol and water (methanol / water = 80/20 volume ratio) of about 10 times the amount of white precipitate (copolymer). A precipitate of B-1) was obtained. The precipitate was filtered off and again poured into a mixed solvent of methanol and water in the same amount as above (methanol / water = 90/10 volume ratio), and the precipitate was washed with stirring. And the precipitate after washing | cleaning was separated by filtration, and copolymer wet powder was obtained. This copolymer wet powder was dried under reduced pressure at 40 ° C. for about 40 hours to obtain a white powder (66.0 g).

And the obtained white powder was analyzed by ¹ H-NMR and GPC, and the average monomer composition and Mw of the whole copolymer were determined. Further, the solubility of the obtained copolymer B-1 was evaluated by the above method. The results are shown in the table of FIG. FIG. 4 shows the molar ratio of monomers m-1, m-2 and m-3, the molecular weight, and the evaluation distance L as an evaluation value in each composition of the copolymers B-1, B-2 and B-3. It is a figure of the table which shows (S), time (minute) which shows solubility, and the exposure amount as a sensitivity.

[Production of resist composition]
100 parts of the copolymer B-1 obtained above was mixed with 2 parts of triphenylsulfonium triflate as a photoacid generator and 700 parts of PGMEA as a solvent to obtain a uniform solution, and then the pore size was 0.1 μm. And a membrane composition filter to prepare a resist composition solution. The sensitivity of the obtained resist composition was evaluated by the above method. The results are shown in the table of FIG.

<Synthesis Example 8: Copolymer B-2>
In Synthesis Example 7, a copolymer was synthesized by a total dropping method without previously putting a monomer in the flask. The molar ratio of the monomers used in this synthesis example is (m-1) :( m-2) :( m-3) = 40.0: 40.0: 20.0.
That is, 64.5 parts of ethyl lactate was placed in the same flask as in Synthesis Example 7 under a nitrogen atmosphere. The flask was placed in a hot water bath, and the temperature of the hot water bath was raised to 80 ° C. while stirring the flask.
Thereafter, 27.20 parts of monomer (m-1), 31.36 parts of monomer (m-2), 18.88 parts of monomer (m-3), and 112.6 ethyl lactate Part, dimethyl-2,2′-azobisisobutyrate (above, V601 (trade name)) was dropped into the flask at a constant rate over 4 hours from 2.576 parts. Furthermore, the temperature of 80 degreeC was hold | maintained for 3 hours.
Thereafter, precipitation of a white precipitate (copolymer B-2) was obtained in the same manner as in Synthesis Example 7, followed by filtration, washing, filtration after washing, and drying to obtain a white powder (64.0 g). Got.
The obtained copolymer B-2 was subjected to the same measurement and evaluation as in Synthesis Example 7. The results are shown in the table of FIG.

<Synthesis Example 9: Copolymer B-3>
In Synthesis Example 7, all the monomers and the solvent were charged in the flask in advance, and the copolymer was synthesized by a batch method. The molar ratio of the monomers used in this example is (m-1) :( m-2) :( m-3) = 40.0: 40.0: 20.0.
That is, in a 25 mL Schlenk flask, 15.5 parts of ethyl lactate, 1.36 parts of monomer (m-1), 1.57 parts of monomer (m-2), monomer (m -3) 0.94 parts and dimethyl-2,2′-azobisisobutyrate (Wako Pure Chemical Industries, V601 (trade name)) 1.15 parts were added, and then 200 mL / min. Nitrogen was blown for 1 minute. The flask was then placed on a 80 ° C. hot water bath and stirred for 3 hours with stirring.

Next, the obtained reaction solution was added dropwise to about 10 times amount of methanol with stirring to obtain a white precipitate (copolymer B-3). And the precipitate after washing | cleaning was separated by filtration, and copolymer wet powder was obtained. This copolymer wet powder was dried under reduced pressure at 40 ° C. for about 40 hours to obtain a white powder (2.8 g).
The obtained copolymer B-3 was subjected to the same measurement and evaluation as in Synthesis Example 7. The results are shown in the table of FIG.

<Synthesis Example 10: Copolymer B-4>
In this synthesis example, monomers (m-4), (m-5), and (m-3) were partially polymerized by a dropping method. The molar ratio of the total amount of each monomer used is (m-4) :( m-5) :( m-3) = 35.5: 34.3: 30.2.

In a flask similar to Synthesis Example 7, in a nitrogen atmosphere, 42.6 parts of ethyl lactate, 41.5 parts of PGMEA, 2.83 parts of monomer (m-4), monomer (m-5) ) And 8.68 parts of monomer (m-3). The flask was placed in a hot water bath, and the temperature of the hot water bath was raised to 80 ° C. while stirring the flask.
Thereafter, it is dropped into the flask at a constant rate for 20 minutes from a dropping device containing 6.5 parts of ethyl lactate and 2.152 parts of dimethyl-2,2′-azobisisobutyrate (above, V601 (trade name)). In addition, the monomer (m-4) was 18.09 parts, the monomer (m-5) was 20.83 parts, the monomer (m-3) was 21.15 parts, and ethyl lactate was 38.6. Part, PGMEA 45.1 parts, dimethyl-2,2'-azobisisobutyrate (above, V601 (trade name)) 1.435 parts from a dropping apparatus into the flask at a constant rate for 4 hours. It was dripped. Furthermore, the temperature of 80 degreeC was hold | maintained for 3 hours.

Next, the polymerization reaction solution in the flask was dropped into the mixture while stirring a mixed solvent (methanol / water = 85/15 volume ratio) of about 10 times the amount of methanol and water, and a white precipitate (copolymer) was added. B-4) was obtained. The precipitate was separated by filtration, and again poured into a mixed solvent of methanol and water in the same amount as above (methanol / water = 95/5 volume ratio), and the precipitate was washed with stirring. And the precipitate after washing | cleaning was separated by filtration, and copolymer wet powder was obtained. This copolymer wet powder was dried under reduced pressure at 40 ° C. for about 40 hours to obtain a white powder (54.1 g).
The obtained copolymer B-4 was subjected to the same measurement and evaluation as in Synthesis Example 7. The results are shown in the table of FIG. FIG. 5 shows the molar ratio of monomers m-4, m-5 and m-3, the molecular weight, and the evaluation distance L as an evaluation value in each composition of the copolymers B-4, B-5 and B-6. It is the figure of the table in which (S), time (minute) which shows solubility, and the exposure amount as a sensitivity were shown.

<Synthesis Example 11: Copolymer B-5>
In Synthesis Example 10, a copolymer was synthesized by a total dropping method without previously putting a monomer in the flask. The molar ratio of the monomers used in this synthesis example is (m-4) :( m-5) :( m-3) = 35.0: 35.0: 30.0.
That is, 54.5 parts of ethyl lactate and 23.3 parts of PGMEA were placed in a flask similar to Synthesis Example 7 under a nitrogen atmosphere. The flask was placed in a hot water bath, and the temperature of the hot water bath was raised to 80 ° C. while stirring the flask.

Next, 51.17 parts of monomer (m-4), 37.32 parts of monomer (m-5), 30.44 parts of monomer (m-3), and 98.98 parts of ethyl lactate. In a flask over 4 hours at a constant rate from a dropping apparatus containing 0 part, 16.4 parts of PGMEA, and 5.538 parts of dimethyl-2,2′-azobisisobutyrate (above, V601 (trade name)) It was dripped in. Furthermore, the temperature of 80 degreeC was hold | maintained for 3 hours.
Then, a white precipitate (copolymer B-5) was obtained in the same manner as in Synthesis Example 10, filtered, washed, filtered after washing, and dried to obtain a white powder (51.0 g). Obtained.
The obtained copolymer B-5 was measured and evaluated in the same manner as in Synthesis Example 7. The results are shown in the table of FIG.

<Synthesis Example 12: Copolymer B-6>
In Synthesis Example 10, all the monomers and the solvent were charged in the flask in advance, and the copolymer was synthesized by a batch method. The molar ratio of the monomers used in this synthesis example is (m-4) :( m-5) :( m-3) = 36.0: 32.0: 32.0.
That is, in a 25 mL Schlenk flask, 4.9 parts of ethyl lactate, 4.9 parts of PGMEA, 1.84 parts of monomer (m-4), and 2.38 of monomer (m-5). Parts, 2.27 parts of monomer (m-3), and 1.725 parts of dimethyl-2,2′-azobisisobutyrate (manufactured by Wako Pure Chemical Industries, Ltd., V601 (trade name)) Nitrogen was bubbled through the solution at 200 mL / min for 1 minute. The flask was then placed on a 80 ° C. hot water bath and stirred for 3 hours with stirring.

Next, the obtained reaction solution was added dropwise to about 10 times amount of methanol with stirring to obtain a white precipitate (copolymer B-6). And the precipitate after washing | cleaning was separated by filtration, and copolymer wet powder was obtained. This copolymer wet powder was dried under reduced pressure at 40 ° C. for about 40 hours to obtain a white powder (6.1 g).
The obtained copolymer B-6 was measured and evaluated in the same manner as in Synthesis Example 7. The results are shown in the table of FIG.

<Synthesis Example 13: Copolymer B-7>
In this synthesis example, the monomers (m-1), (m-6), and (m-3) were synthesized by a method (total dropping method) in which the monomers were previously polymerized without putting them into the flask. The molar ratio of the total amount of each monomer used is (m-1) :( m-6) :( m-3) = 40.0: 40.0: 20.0.
That is, 43.1 parts of DMF was placed in the same flask as in Example 7 under a nitrogen atmosphere. The flask was placed in a hot water bath, and the temperature of the hot water bath was raised to 80 ° C. while stirring the flask.
Thereafter, the monomer (m-1) was 10.21 parts, the monomer (m-6) was 8.53 parts, the monomer (m-3) was 7.09 parts, and the DMF was 60.3 parts. Dimethyl-2,2′-azobisisobutyrate (above, V601 (trade name)) was added dropwise into the flask at a constant rate over 3 hours from a dropping device containing 0.449 parts. Furthermore, the temperature of 80 degreeC was hold | maintained for 3 hours.

Next, the polymerization reaction solution in the flask was added dropwise with stirring about 10 times the amount of methanol and water mixed solvent (methanol / water = 70/30 volume ratio), and a white precipitate (co-polymer) was added. A precipitate of coalescence B-7) was obtained. The precipitate was separated by filtration and again poured into a mixed solvent of methanol and water in the same amount as above (methanol / water = 70/30 volume ratio), and the precipitate was washed with stirring. And the precipitate after washing | cleaning was separated by filtration, and copolymer wet powder was obtained. This copolymer wet powder was dried under reduced pressure at 40 ° C. for about 40 hours to obtain a white powder (20.1 g).
The obtained copolymer B-7 was measured and evaluated in the same manner as in Synthesis Example 71. The results are shown in the table of FIG. FIG. 6 shows the molar ratio of monomers m-1, m-6 and m-3, the molecular weight, the evaluation distance L (S) as the evaluation value, and the dissolution in each composition of the polymers B-7 and B-8. 5 is a table showing the time (minutes) showing the property and the exposure amount as sensitivity.

<Synthesis Example 14: Copolymer B-8>
In Synthesis Example 13, all the monomers and the solvent were charged in the flask in advance, and the copolymer was synthesized by a batch method. The molar ratio of the monomers used in this synthesis example is (m-1) :( m-6) :( m-3) = 40.0: 40.0: 20.0.
That is, in a 25 mL Schlenk flask, 8.3 parts of DMF, 0.82 parts of monomer (m-1), 0.68 parts of monomer (m-6), monomer (m- 3) 0.57 parts and dimethyl-2,2′-azobisisobutyrate (Wako Pure Chemical Industries, Ltd., V601 (trade name)) 0.332 parts were put into the solution at 200 mL / min. Nitrogen was blown for 1 minute. The flask was then placed on a 80 ° C. hot water bath and stirred for 6 hours with stirring.

Subsequently, the obtained reaction solution was dropped into a mixed solvent of methanol and water of about 10 times amount (methanol / water = 80/20 volume ratio) with stirring, and a white precipitate (copolymer B-8) A precipitate was obtained. And the precipitate after washing | cleaning was separated by filtration, and copolymer wet powder was obtained. This copolymer wet powder was dried under reduced pressure at 40 ° C. for about 40 hours to obtain a white powder (1.5 g).
The obtained copolymer B-8 was measured and evaluated in the same manner as in Synthesis Example 71. The results are shown in the table of FIG.

<Application example 1>
A total of 6 types of ¹³ C-NMR measurements of the homopolymers A-1 to A-3 obtained in Synthesis Examples 1 to 3 and the copolymers B-1 to B-3 obtained in Synthesis Examples 7 to 9 were performed. Each was performed in the NMR measurement unit 50.
And in the NMR measurement part 50, the NMR spectrum of each sample is obtained. The NMR measurement unit 50 sets the number of integrations at the time of measurement to 5000 times, the broadening factor at the time of FID processing to 4.0 Hz, the reference peak as dimethyl sulfoxide (39.5 ppm), and performs baseline correction of the measured NMR spectrum. The obtained FID data of each sample is output to the waveform processing unit 11.

Next, the waveform processing unit 11 integrates a range of 175 to 179 ppm derived from the carbonyl carbon of the polymer from each of the frequencies of the NMR spectrum in the obtained FID signal at intervals of 0.25 ppm, An integral value was obtained.
And the waveform process part 11 provides monomer identification information (for example, A-1 to A-3) to each of homopolymer A-1 to A-3, and makes it respond | correspond to this monomer identification information. Then, the NMR spectrum data of each homopolymer is written and stored in the NMR data storage unit 15.
In addition, the waveform processing unit 11 assigns sample identification information (for example, B-1 to B-3) to each of the copolymers B-1 to B-3, and corresponds to the sample identification information, so that each sample The NMR spectrum data of the copolymer is written and stored in the NMR data storage unit 15.

  Next, the principal component analysis unit 12 uses, for example, Sirius (registered trademark) manufactured by Pattern Recognition System, as multivariate analysis software, and includes homopolymers A-1 to A-3 and copolymers B-1 to B. -3, a principal component analysis is performed on a total of 16 integral values related to carbonyl carbon from the NMR spectrum data of a total of 6 types of polymers, and an experimental model of matrix G shown in Equation (1) is constructed.

As a result, since there are three types of monomers in the copolymer composition, the dimension of the principal component space in which the sample to be evaluated is arranged is three dimensions, that is, the number of principal components is three. The respective contribution ratios of the first main component to the third main component were 67.1%, 24.5%, and 7.9%, respectively, and the residue was 0.5%.
The first main component (hereinafter referred to as PC1), the second main component (hereinafter referred to as PC2), and the first of each of the homopolymers A-1 to A-3 and the copolymers B-1 to B-3, and The principal component scores (scores) of the three principal components (hereinafter PC3) are as shown in the table of FIG. FIG. 7 shows the first principal component, the second principal component, and the third principal component A-1 to A-3 and the copolymers B-1 to B-3 calculated by the principal component analysis unit 12. It is a figure which shows the main component score of each main component.

Next, the numerical value conversion unit 13 includes homopolymers A-1 to A in a three-dimensional space composed of the first principal component axis PC1, the second principal component axis PC2, and the third principal component axis PC3 shown in FIG. -3 and the coordinates of copolymer B-1 to B-3 (position in the principal component space indicated by the principal component score of each axis) 2 formed by homopolymers A-1 to A-3 The evaluation distance L (S) from the dimensional space (two-dimensional plane) to each coordinate of the polymers B-1 to B-3 is calculated.
Here, the numerical value conversion unit 13 includes each of the homopolymers A-1, A-2, A-3 and the copolymers B-1, B-2, B-3 in the principal component space which is a three-dimensional space. Are coordinate values PC1 (X) of the first principal component axis PC1, coordinate values PC2 (X) of the second principal component axis PC2, and coordinate values PC3 (X of the third principal component axis PC3. ) Is used as follows. Moreover, X in () in the coordinate value is sample identification information indicating a sample of the copolymer to be evaluated.

Coordinate value of homopolymer A-1:
P (A-1) = (PC1 (A-1), PC2 (A-1), PC3 (A-1))
Coordinate value of homopolymer A-2:
P (A-2) = (PC1 (A-2), PC2 (A-2), PC3 (A-2))
Coordinate value of homopolymer A-3:
P (A-3) = (PC1 (A-3), PC2 (A-3), PC3 (A-3))
Coordinate value of copolymer B-1:
P (B-1) = (PC1 (B-1), PC2 (B-1), PC3 (B-1))
Coordinate value of copolymer C-1:
P (C-1) = (PC1 (C-1), PC2 (C-1), PC3 (C-1))
Coordinate value of copolymer D-1:
P (D-1) = (PC1 (D-1), PC2 (D-1), PC3 (D-1))

  Here, the homopolymers A-1, A-2, and A-3 are bonded in such a manner that monomers as a single constituent unit are arranged completely continuously in the polymer chain. For this reason, in the two-dimensional plane (two-dimensional comparison space) passing through all the coordinate values P (A-1), P (A-2), and P (A-3), the continuity of the monomer of the structural unit is high. It is a two-dimensional space that is one dimension less than the principal component space, which is formed by a set of copolymers having the highest, in other words, the smallest randomness. Therefore, as already described, the evaluation distance L (S) from the two-dimensional plane to the copolymer to be evaluated is a distance from the two-dimensional plane showing the property with the least randomness, and in the copolymer This shows the randomness of the arrangement of the monomers in the chain.

And the numerical value conversion part 13 calculates | requires numerical value a, b, c, d like the following Formula.
a = (PC2 (A-2) -PC2 (A-1)) * (PC3 (A-3) -PC3 (A-1))-(PC2 (A-3) -PC2 (A-1)) * (PC3 (A-2) -PC3 (A-1))
b = (PC3 (A-2) -PC3 (A-1)) * (PC1 (A-3) -PC1 (A-1))-(PC3 (A-3) -PC3 (A-1)) * (PC1 (A-2) -PC1 (A-1))
c = (PC1 (A-2) -PC1 (A-1)) * (PC2 (A-3) -PC2 (A-1))-(PC1 (A-3) -PC1 (A-1)) * (PC2 (A-2) -PC2 (A-1))
d =-(PC2 (A-2) -PC2 (A-1)) * (PC3 (A-3) -PC3 (A-1))-(PC2 (A-3) -PC2 (A-1)) * (PC3 (A-2) -PC3 (A-1)) * PC1 (A-1)-(PC3 (A-2) -PC3 (A-1)) * (PC1 (A-3) -PC1 ( A-1))-(PC3 (A-3) -PC3 (A-1)) * (PC1 (A-2) -PC1 (A-1)) * PC1 (A-2)-(PC1 (A- 2) -PC1 (A-1)) * (PC2 (A-3) -PC2 (A-1))-(PC1 (A-3) -PC1 (A-1)) * (PC2 (A-2)) -PC2 (A-1)) x PC1 (A-3)

Next, the numerical value conversion unit 13 includes a two-dimensional plane that passes through all three coordinate points P (A-1), P (A-2), and P (A-3), and the coordinates of the copolymer to be evaluated. The evaluation distance L (S) with the point P (PC1, PC2, PC3) is calculated by the following formula using the obtained numerical values a, b, and c.
L = | a × SPC1 + b × SPC2 + c × SPC3 + d | / (a ² + b ² + c ² ) ^1/2
In this equation, SPC1 is a coordinate value on the first principal component axis of the copolymer to be evaluated (the principal component score of the first principal component), and SPC2 is a coordinate on the second principal component axis of the copolymer to be evaluated. SPC3 is a coordinate value on the third principal component axis of the copolymer to be evaluated (the principal component score of the third principal component).
As described above, the coordinate point indicates the position in the principal component space of the characteristics of the copolymer to be evaluated, and the coordinate point P (A of the homopolymer consisting of each of the three monomers forming the copolymer. -1), P (A-2), and evaluation distance L (S) with a two-dimensional plane passing through all of P (A-3) are shown in the table of FIG. As can be seen from the table of FIG. 4, the larger the evaluation distance L (S), the higher the randomness of the copolymer chain, and the better the lithography characteristics of solubility and sensitivity to light.
As can be seen from FIG. 4, the evaluation distance L (S) becomes longer in the order of the copolymers B-3, B-2, and B-1, and the solubility of the resist composition produced by adjusting this copolymer is increased. It can be seen that the lithography characteristics of the sensitivity to light and light are improved as the evaluation distance L (S) becomes longer in the order of the copolymers B-3, B-2, and B-1. Therefore, by adjusting the resist composition used as a resist, and determining the evaluation distance L (S) of the copolymer used for adjusting the resist composition without actually performing lithography, this copolymer can be obtained. The lithography properties of the resist composition adjusted from the above can be estimated. Here, the copolymer B3 has such a low sensitivity that light cannot be measured, and the solubility is not completely dissolved within the measurable time.

<Application example 2>
A total of 6 types of ¹³ C-NMR measurements of the homopolymers A-3 to A-5 obtained in Synthesis Examples 3 to 5 and the copolymers B-4 to B-6 obtained in Synthesis Examples 10 to 12 were performed. Each was done to obtain a spectrum. Baseline correction was performed by setting the number of integrations at the time of measurement to 5000 times, the broadening factor at the time of FID treatment to 4.0 Hz, and the reference peak to dimethyl sulfoxide (39.5 ppm).

Next, from each of the obtained spectra, the range of 173 to 179 ppm derived from the carbonyl carbon of the polymer was integrated at intervals of 0.25 ppm, and 20 integrated values were obtained.
The evaluation distance L (S) from the plane which passes along the point which consists of a main component score and the main component score about all the homopolymers similarly to the application example 1 was calculated | required.
The principal component scores (scores) of the principal components indicating the coordinate values of the first principal component axis PC1, the second principal component axis PC2, and the third principal component axis PC3 are shown in the table of FIG. The result of S) is shown in the table of FIG. FIG. 8 shows the first main component, the second main component and the third main component of each of the homopolymers A-3 to A-5 and the copolymers B-4 to B-6 calculated by the principal component analysis unit 12. It is a figure which shows the main component score of each main component.
As can be seen from FIG. 5, the evaluation distance L (S) becomes longer in the order of copolymers B-6, B-5, and B-4, and the solubility of the resist composition produced by adjusting this copolymer is increased. It can be seen that the lithography characteristics of the sensitivity to light and light improve as the evaluation distance L (S) becomes longer in the order of the copolymers B-6, B-5, and B-4. Therefore, by adjusting the resist composition used as a resist, and determining the evaluation distance L (S) of the copolymer used for adjusting the resist composition without actually performing lithography, this copolymer can be obtained. The lithography properties of the resist composition adjusted from the above can be estimated. Here, the copolymer B6 has such a low sensitivity that light cannot be measured, and the solubility is not completely dissolved within the measurable time.

<Application example 3>
A total of five types of homopolymers A-1, A-3, A-6 obtained in Synthesis Examples 1, 3, 6 and copolymers B-7 and B-8 obtained in Synthesis Examples 13-14 Each ¹³ C-NMR measurement was performed to obtain a spectrum. Baseline correction was performed by setting the number of integrations at the time of measurement to 5000 times, the broadening factor at the time of FID processing to 3.0 Hz, and the reference peak to dimethyl sulfoxide (39.5 ppm).

Next, as described above, from the NMR spectrum signal of each polymer, the range of 174 to 179 ppm derived from the carbonyl carbon of the polymer is integrated at intervals of 0.25 ppm, and 16 integrated values are obtained. Obtained.
As in Example 1, the principal component analysis of the NMR spectrum data obtained from the NMR spectrum signal is performed, and the evaluation distance L (from the plane passing through the principal component score, the point consisting of the principal component scores for all homopolymers) S) was determined.
The principal component scores (scores) of the principal components indicating the coordinate values of the first principal component axis PC1, the second principal component axis PC2, and the third principal component axis PC3 are shown in the table of FIG. The result of S) is shown in the table of FIG. FIG. 9 shows the first principal component and the second principal component of each of the homopolymers A-1, A-3 and A-6 and the copolymers B-7 and B-8 calculated by the principal component analysis unit 12. It is a figure which shows the main component score of a component and each 3rd main component.
As can be seen from FIG. 6, the evaluation distance L (S) becomes longer in the order of the copolymers B-8 and B-7, and the solubility and the sensitivity to light of the resist composition produced by adjusting this copolymer. It can be seen that the lithographic characteristics are improved as the evaluation distance L (S) becomes longer in the order of the copolymers B-8 and B-7. Therefore, by adjusting the resist composition used as a resist, and determining the evaluation distance L (S) of the copolymer used for adjusting the resist composition without actually performing lithography, this copolymer can be obtained. The lithography properties of the resist composition adjusted from the above can be estimated.

  In the present embodiment, based on the results shown in the tables of FIGS. 4, 5, and 6, there is a correlation between the value of the evaluation distance L (S) and Eth indicating the solubility or sensitivity related to the development defect. It has been confirmed that the lithography characteristics can be indirectly evaluated by the value of L (S). From this, it was confirmed that indirect evaluation of lithography characteristics can be performed with high accuracy by the method of the present invention.

Next, when the number of monomers constituting the copolymer is n, the numerical value conversion unit 12 shows an expression for obtaining the evaluation distance L (S). In this case, since the number of types of monomers is n, the principal component space is n-dimensional, and in this n-dimensional space, the number of coordinate points of the homopolymer consisting only of each monomer is n, The space including all the coordinate points is n-1 dimensions. Therefore, the evaluation distance L (S) is obtained as the evaluation distance L (S) from the coordinate point of the sample to be evaluated to the n−1-dimensional space described above.
The evaluation distance L (S) from an arbitrary coordinate point in the n-dimensional space to the n−1-dimensional space projects the arbitrary coordinate point to the n−1-dimensional space, and n is projected onto the n−1-dimensional space. The length of the shortest geodesic line connecting the coordinate point indicating the position in the −1-dimensional space and the arbitrary coordinate point is obtained.

For example, in an n-dimensional space formed by the first principal component axis PC1 to the n-th principal component axis PCn, n− including all coordinate points (positions indicated by n principal component scores) of the respective homopolymer samples. Find a one-dimensional space.
Here, the numerical value conversion unit 13 calculates the coordinate value (principal component score) on each first principal component axis PC1 for the polymers A-1 to An composed of a single structural unit,. Coordinate points P (A-1) to P (An) are defined by coordinate points composed of coordinate values (principal component scores) on the principal component axis PCn.

The numerical value conversion unit 13 includes an n-1 dimensional space passing through all the coordinate points P (A-1) to P (An), and the coordinate point P (PC1, PC2,... The evaluation distance L (S) with respect to PCn) is calculated by the following formula.
L (S)
_{= | A 1 × SPC1 + a} 2 × SPC2 + ... + a n × SPCn + a n + 1 | / (a 1 2 + a 2 2 + ... + a n 2) 1/2
In this equation, SPC1 is a coordinate value on the first principal component axis of the copolymer to be evaluated (the principal component score of the first principal component), and SPC2 is a coordinate on the second principal component axis of the copolymer to be evaluated. Is the value (the principal component score of the second principal component),..., SPCn is the coordinate value (the principal component score of the nth principal component) on the n-th principal component axis of the copolymer to be evaluated.

However, in the above formula for calculating the evaluation distance L (S) in the n-dimensional principal component space,
_{a 1 × SPC1 + a 2 ×} SPC2 + ... + a n × SPCn + a n + 1 = 0
The n-1 dimensional comparison space represented by the relationship (one dimension less than the principal component space) passes through all the n coordinate points P (A-1) to P (An).
Here, the numerical value conversion unit 13 indicates that the numerical values (coefficients) a ₁ to a _{n + 1} in the above expression are coordinates of the coordinate point P (A-1) with respect to the expression in the n−1 dimensional space that is the comparison space. It is calculated by solving the n-ary simultaneous equations substituted with.

  As described above, in the processing of the principal component analysis unit 12, the resist copolymer is S, and the resist copolymer S is composed of n (n is an integer of 2 or more) structural units (monomers). In this case, with respect to the chemical shift and the signal intensity in the NMR measurement of the resist copolymer S and the homopolymer Aj (j = 1 ·· n) consisting of only a single constituent monomer. The principal component analysis is performed to calculate the principal component score Pj of each principal component. Since n types of monomers form the resist copolymer S, n main component axes are formed because the nth main component (from the first main component to the nth main component) is used.

Then, the numerical value conversion unit 13 converts each of the principal component scores of the homopolymer A-j into each principal component axis in an n-dimensional principal component space composed of n principal component axes (coordinate axes that are orthogonal to each other). As a coordinate value, coordinate points in the principal component space are formed.
In addition, the numerical value conversion unit 13 sets a point composed of the main component score Pi (S) for the resist copolymer S to be evaluated as a coordinate point P (S), and uses the main component score Pi for the homopolymer A-j. The coordinate point consisting of (A−j) is P (A−j), and the distance between the coordinate point P (S) and the (n−1) -dimensional space passing through all the coordinate points P (A−j) is the evaluation distance L Calculate as (S).
Then, the characteristic evaluation unit 14 performs processing for evaluating the lithography characteristic of the resist copolymer to be evaluated based on the evaluation distance L (S) calculated by the numerical value conversion unit 13 (using the above-described threshold value, Evaluation of lithography properties of a resist composition obtained by preparing a polymer).

Further, in the present embodiment, the evaluation of the resist copolymer is described as an example of a copolymer composed of a plurality of (two or more types) monomers, but a plurality of single units including the lithography copolymer are described. It is also possible to qualitatively evaluate the state of monomer arrangement in the composition of these copolymers, with a copolymer consisting of a monomer as an evaluation target.
Then, by correlating the state of monomer arrangement in the composition of the copolymer with the characteristics including the physical properties of the copolymer, it can be used for resists without actually conducting experiments using the copolymer. Similar to the copolymer, the properties of the copolymer can be estimated from the evaluation distance L (S).

  Further, the program for realizing the functions of the waveform processing unit 11, the principal component analysis unit 12, the numerical value conversion unit 13 and the characteristic evaluation unit 14 in FIG. 1 is recorded on a computer-readable recording medium, and recorded on this recording medium. The composition analysis of the copolymer may be performed by causing the computer system to read and execute the program. Here, the “computer system” includes an OS and hardware such as peripheral devices.

Further, the “computer system” includes a homepage providing environment (or display environment) if a WWW system is used.
The “computer-readable recording medium” refers to a storage device such as a flexible medium, a magneto-optical disk, a portable medium such as a ROM and a CD-ROM, and a hard disk incorporated in a computer system. Furthermore, the “computer-readable recording medium” dynamically holds a program for a short time like a communication line when transmitting a program via a network such as the Internet or a communication line such as a telephone line. In this case, a volatile memory in a computer system serving as a server or a client in that case, and a program that holds a program for a certain period of time are also included. The program may be a program for realizing a part of the functions described above, and may be a program capable of realizing the functions described above in combination with a program already recorded in a computer system.

  The embodiment of the present invention has been described in detail with reference to the drawings. However, the specific configuration is not limited to this embodiment, and includes design and the like within a scope not departing from the gist of the present invention.

DESCRIPTION OF SYMBOLS 1 ... Copolymer composition analyzer 11 ... Waveform processing part 12 ... Principal component analysis part 13 ... Numerical value conversion part 14 ... Characteristic evaluation part 15 ... NMR data storage part 16 ... Principal component data storage part 50 ... NMR measurement part

Claims (5)

It is a copolymer composition analysis method of the arrangement state of the monomer units in the copolymer,
A measurement data extraction process in which a measurement data extraction unit extracts, as copolymer measurement data, an NMR spectrum in a range including the wavelength of each of the monomers constituting the copolymer from the NMR spectrum of the copolymer; ,
The principal component analysis unit performs principal component analysis on the chemical shift and the spectral intensity between the copolymer measurement data and the monomer measurement data of each NMR spectrum of the monomer. n is an integer greater than or equal to 2)
The numerical conversion unit includes all coordinate points represented by the principal component scores of the monomer on the principal component axis in the n-dimensional principal component space formed by the principal component axes of the first principal component to the n-th principal component. A distance calculation process for obtaining an evaluation distance from the n-1 dimensional comparison space to the target coordinate point represented by the main component score of the copolymer;
A property evaluation unit comprising: a property evaluation process for evaluating the composition of the copolymer based on the evaluation distance.   2. The copolymer composition analysis method according to claim 1, wherein the characteristic evaluation unit evaluates a length in which the monomers of the same type are continuously arranged in the composition of the copolymer based on the evaluation distance. 3. .   The said characteristic evaluation part has a threshold value for determining the said evaluation distance, and evaluates the characteristic of the composition adjusted using the said copolymer by the comparison with the said evaluation distance and the said threshold value. Alternatively, the copolymer composition analysis method according to claim 2. The copolymer is a resist copolymer,
The characteristic evaluation unit
The copolymer composition analysis method according to claim 3, wherein lithography characteristics including solubility in a solvent and sensitivity in exposure are evaluated by comparing the evaluation distance with the threshold value. A program for causing a computer to be used in a copolymer composition analysis method of an arrangement state of monomer units in a copolymer,
Measurement data extraction process for extracting the measurement data extraction unit from the NMR spectrum of the copolymer as an NMR measurement data in a range including the wavelength of each of the monomers constituting the copolymer When,
The principal component analysis unit performs principal component analysis on the chemical shift and the spectral intensity between the copolymer measurement data and the monomer measurement data of each NMR spectrum of the monomer. n is an integer greater than or equal to 2)
The numerical conversion unit includes all coordinate points represented by the principal component scores of the monomer on the principal component axis in the n-dimensional principal component space formed by the principal component axes of the first principal component to the n-th principal component. A distance calculation process for obtaining an evaluation distance from the n-1 dimensional comparison space to the target coordinate point represented by the main component score of the copolymer;
A characteristic evaluation unit causes a computer to execute characteristic evaluation processing for evaluating the composition of the copolymer based on the evaluation distance.

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