TW201520233A - Semiconductor wetting agent and polishing composition - Google Patents

Abstract

A semiconductor wetting agent including an aqueous polymer having within a molecule 70-99 mol% of the structural unit represented by formula (1), and 1-30 mol% of the specific structural unit represented by formula (2). [-CH2CH(OH)-] (1) [-CH2CH(X)-] (2) (In formula (2), X represents an alkyl ether group or the like having an alkyl group with a carbon number of 1-10).

Description

Wetting agent for semiconductor and polishing composition Cross-reference to related applications

The present application is related to the Japanese Patent Application No. 2013-209778, filed on Jan. 7, 2013, the entire contents of This specification is incorporated by reference.

The present invention relates to a wetting agent for semiconductors and a polishing composition, and more particularly to a semiconductor wetting agent and a polishing composition used for final polishing of a tantalum wafer or the like.

In information communication devices such as computers and mobile phones, and digital home appliances such as digital cameras and televisions, semiconductor devices using a silicon wafer as a substrate are widely used. With the recent increase in the size and capacity of semiconductor wafers, the processing accuracy of semiconductor devices is becoming finer, and the smoothness of wafers before device formation and the so-called non-invasiveness without defects such as scratches The requirements are becoming stricter.

As a wafer smoothing technology, it is often used as the so-called "CMP (Chemical Mechanical Poshing)" polishing process. In the smoothing treatment by CMP, a polishing composition containing fine abrasive grains and a basic compound is used. While the polishing composition is supplied to the surface of the polishing pad, the pressure-sensitive polishing pad is moved relative to the wafer as the object to be polished to polish the surface. At this time, by performing mechanical polishing using abrasive grains and chemical polishing using an alkaline compound at the same time, it is possible to cover a wide range of wafer surface smoothing with high precision.

In general, in wafer polishing using CMP, high-precision smoothing is achieved by performing 3 to 4 stages of polishing. The primary polishing and the secondary polishing performed in the first stage and the second stage have a tendency to emphasize the polishing rate because the surface is smoothed. On the other hand, in the final polishing of the third stage or the fourth stage, the haze on the surface of the wafer and the suppression of COP (Crystal Originated Particles), or even the agglomerated abrasive grains and polishing padding can be used. The prevention of contamination caused by the adhesion of so-called particles such as tantalum powder removed by grinding is emphasized.

As a polishing composition used for the final polishing, it is known that a method of adding a water-soluble polymer compound to a polishing composition is effective. Patent Document 1 discloses a polishing composition comprising a water-soluble polymer compound having a molecular weight of 100,000 or more and a water-soluble salt. Further, Patent Document 2 describes a polishing composition containing a water-soluble polymer compound, and teaches that a cellulose derivative or polyvinyl alcohol can be used as the water-soluble polymer compound.

[Previous Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open No. Hei 2-158684

[Patent Document 2] Japanese Patent Laid-Open No. Hei 11-116942

However, in the invention described in Patent Document 1, the water-soluble polymer compound used has insufficient adsorption property on the surface of the wafer, and the haze and COP of the wafer surface after the final polishing cannot be satisfied. Moreover, the water-soluble salt added for the purpose of improving the polishing property is also inferior from the viewpoint of the dispersibility of the cerium oxide abrasive grains. When the dispersibility of the cerium oxide abrasive grains is insufficient, there is a tendency that the surface roughness of the surface of the wafer after the final polishing is likely to increase, and scratches and the like are caused.

Further, the cellulose derivative or polyvinyl alcohol described in Patent Document 2 is also insufficient in the adsorption property to the surface of the wafer. In addition, in the examples of Patent Document 2, an experimental example in which hydroxyethyl cellulose is used as a specific water-soluble polymer compound is disclosed, but since it is a compound derived from a natural product, there is also a so-called quality unevenness. The problem.

The present invention has been made in view of such circumstances, and provides a wetting agent for semiconductors and a polishing agent which can effectively smooth the surface of a wafer during surface polishing of a tantalum wafer and is effective for suppressing COP. The composition is the subject.

As a result of intensive studies to solve the above problems, the present inventors have found that smoothing of the surface of the wafer after polishing and COP suppression by using a wetting agent for a semiconductor containing a polyvinyl alcohol polymer having a specific structural unit. The effect can be exerted to complete the present invention.

The invention is as follows:

[1] A wetting agent for a semiconductor comprising a water-soluble polymer having 70 to 99 mol% of a structural unit represented by the formula (1) and 1 to 30 mol% of a structural unit represented by the formula (2) in a molecule. ;[-CH ₂ CH(OH)-] (1)

[-CH ₂ CH(X)-] (2) In the formula (2), X represents an alkyl ether group having an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 10 carbon atoms, or a formula (3) or An organic group represented by the formula (4), a urethane alkyl group having an alkyl group having 1 to 10 carbon atoms, an alkylene oxide group having a carbon number of 3 or more alkyl groups, hydrogen or a carbon number of 1 to 3 Alkyl group; -C(=O)O-(CH ₂ ) _m -R ¹ (3) In the formula (3), R ¹ represents an alkyl group having 1 to 8 carbon atoms and an alkyl group having 1 to 4 carbon atoms. Alkylamino or dialkylamino group, m represents an integer from 0 to 3; -C(=O)NH-(CH ₂ ) _n -R ² (4) In the formula (4), R ² represents a carbon number of 1~ An alkyl group of 8 or an alkylamino group or a dialkylamino group having an alkyl group having 1 to 4 carbon atoms, and n represents an integer of 0 to 3.

[2] The wetting agent for a semiconductor according to the above [1], wherein the water-soluble polymer is obtained by copolymerizing vinyl acetate and another vinyl monomer, followed by saponification.

[3] The wetting agent for a semiconductor according to the above [1], wherein the water-soluble polymer has a number average molecular weight of 1,000 to 200,000.

[4] A polishing composition comprising the semiconductor wetting agent according to any one of the above [1] to [3], water, abrasive grains, and an alkali compound.

[5] The polishing composition according to [4], wherein the abrasive grains are colloidal cerium oxide.

[6] The polishing composition according to [4] or [5] above, which is the final polishing user of the ruthenium wafer.

[7] A method of polishing a tantalum wafer, which has a water solubility of 70 to 99 mol% of a structural unit represented by the formula (1) and 1 to 30 mol% of a structural unit represented by the formula (2) in a molecule. Molecules, to grind 矽 wafers; [-CH ₂ CH(OH)-] (1)

[-CH ₂ CH(X)-] (2) In the formula (2), X represents an alkyl ether group having an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 10 carbon atoms, or a formula (3) or An organic group represented by the formula (4), a urethane alkyl group having an alkyl group having 1 to 10 carbon atoms, an alkylene oxide group having a carbon number of 3 or more alkyl groups, hydrogen or a carbon number of 1 to 3 Alkyl; -C(=O)O-(CH ₂ ) _m -R ¹ (3) In the formula (3), R ¹ represents an alkyl group having 1 to 8 carbon atoms and an alkyl group having 1 to 4 carbon atoms. Alkylamino or dialkylamino group, m represents an integer from 0 to 3; -C(=O)NH-(CH ₂ ) _n -R ² (4) In the formula (4), R ² represents a carbon number of 1~ An alkyl group of 8 or an alkylamino group or a dialkylamino group having an alkyl group having 1 to 4 carbon atoms, and n represents an integer of 0 to 3.

The wetting agent for semiconductor of the present invention is excellent in adsorptivity to the surface of the wafer after polishing. Therefore, by using the polishing composition containing the semiconductor wetting agent, the smoothness of the surface of the wafer after polishing can be improved, and the etching resistance is excellent, so that COP can be suppressed. Further, since the dispersibility of cerium oxide is also good, scratches or surface cracks due to agglomerated cerium oxide abrasive grains are also small, and a wafer surface excellent in damage-free can be obtained.

Hereinafter, a representative and non-limiting specific example of the present disclosure will be described in detail. The detailed description is only intended to be illustrative of the preferred embodiments of the invention, and is not intended to limit the scope of the disclosure. Further, in addition to the additional features and inventions disclosed below, in order to provide a further improved wetting agent for semiconductors and The polishing composition can be used separately or in combination with other features or inventions.

In addition, the features or combinations of steps disclosed in the following detailed description are not necessarily in the broadest sense, and are merely described as representative examples of the present disclosure. Furthermore, various features of the above-described specific examples and the various features described in the independent and dependent items, when providing an additional and useful embodiment of the present disclosure, must be specifically described herein. For example, or in the order listed.

All the features described in the specification and/or the claims are different from the features described in the embodiments and/or claims, and are intended to be individually and independently defined in the manner in which the application is disclosed and the specifics of the claims. Revealed. In addition, all numerical ranges and group or group-related records are intended to limit the manner in which the application is disclosed and the specifics of the claim, and

Hereinafter, the present invention will be described in detail. Further, in the present specification, "(meth)acryl" refers to acryl and methacryl, and "(meth)acrylate" refers to Acrylates and methacrylates. Further, "(meth)acryloyl" means acryloyl and methacryloyl.

<Water-soluble polymer>

The wetting agent for a semiconductor of the present invention comprises a water-soluble polymer having 70 to 99 mol% of the structural unit represented by the following formula (1) and 1 to 30 mol% of the structural unit represented by the formula (2); [-CH ₂ CH(OH)-] (1)

[-CH ₂ CH(X)-] (2) In the formula (2), X represents an alkyl ether group having an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 10 carbon atoms, or a formula (3) or An organic group represented by the formula (4), a urethane alkyl group having an alkyl group having 1 to 10 carbon atoms, an alkylene oxide group having a carbon number of 3 or more alkyl groups, hydrogen or a carbon number of 1 to 3 Alkyl group; -C(=O)O-(CH ₂ ) _m -R ¹ (3) In the formula (3), R ¹ represents an alkyl group having 1 to 8 carbon atoms and an alkyl group having 1 to 4 carbon atoms. Alkylamino or dialkylamino group, m represents an integer from 0 to 3; -C(=O)NH-(CH ₂ ) _n -R ² (4) In the formula (4), R ² represents a carbon number of 1~ An alkyl group of 8 or an alkylamino group or a dialkylamino group having an alkyl group having 1 to 4 carbon atoms, and n represents an integer of 0 to 3.

The water-soluble polymer of the present invention has a structural unit represented by the formula (1) in a range of 70 to 99 mol%. The preferred range of the structural unit is from 70 to 95 mol%, more preferably from 75 to 90 mol%. The structural unit represented by the formula (1) is important in that the adsorption property to the wafer is good and the solubility of the water-soluble polymer in water is ensured.

The structural unit represented by the formula (1) in the water-soluble polymer is less than 70 mol% In the case where the solubility in water is insufficient, there is a case where the effect of the wetting agent for a semiconductor of the present invention cannot be obtained. In addition, when it is more than 99 mol%, the structural unit represented by the formula (2) is less than 1 mol%, and the adsorption property to the wafer may be insufficient.

In the formula (2), X represents an alkyl ether group having an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 10 carbon atoms, an organic group represented by the formula (3) or the formula (4), and having a carbon number. a urethane group of an alkyl group of 1 to 10, an alkylene oxide group having a alkyl group having 3 or more carbon atoms, hydrogen or an alkyl group having 1 to 3 carbon atoms. X can be one of these, and two or more types can be used in combination. In the above, the alkyl ether group having an alkyl group having 1 to 10 carbon atoms, or the formula (3) or the formula (4) is preferred because it has good adsorptivity to the wafer and is easy to obtain a corresponding raw material. Organic base. Further, from the viewpoint of good alkali hydrolysis resistance, an alkyl ether group having an alkyl group having 1 to 10 carbon atoms is more preferable.

Further, in the water-soluble polymer, the structural unit represented by the formula (2) needs to be in the range of 1 to 30 mol%. The preferred range of the structural unit is from 5 to 30 mol%, more preferably from 10 to 25 mol%. The structural unit represented by the formula (2) is a structural unit which is important for imparting adsorption to a wafer.

When the structural unit represented by the formula (2) is less than 1 mol%, the adsorptivity to the wafer may be insufficient. When the amount is more than 30 mol%, the solubility in water may be insufficient.

The number average molecular weight of the water-soluble polymer is preferably in the range of 1,000 to 200,000, more preferably in the range of 1,500 to 100,000, and still more preferably in the range of 2,000 to 50,000. When the number average molecular weight is 1,000 or more, the wettability of the wafer tends to be good; if it is 200,000 or less, The dispersion of the abrasive grains can be ensured. Further, the number average molecular weight can be measured by GPC (gel permeation chromatography; for example, HLC-8220, manufactured by TOSOH) in terms of polystyrene.

<Method for Producing Water-Soluble Polymer>

The water-soluble polymer of the present invention can have a vinyl ester such as vinyl formate, vinyl acetate or propionic acid acetate in the presence of a polymerization initiator or the like, and has the formula (2), for example, in a polymerization solvent. After the monomer mixture of the monomers of the structural unit shown is copolymerized, the structural unit derived from the vinyl ester is saponified. Further, as the vinyl ester, vinyl acetate is preferred from the viewpoint of polymerization stability and the like.

Further, in contrast to this, it is also possible to carry out the modification of the urethane by reacting a part of the hydroxyl group of the polyvinyl alcohol with an isocyanate compound having an alkyl group having 1 to 10 carbon atoms.

Further, it is also obtainable by adding an alkylene oxide having a carbon number of 3 or more to a part of the hydroxyl group of the polyvinyl alcohol. The alkylene oxide to be added is preferably a carbon number of 3 to 6, more preferably a carbon number of 3 to 4.

Specific examples of the monomer having a structural unit represented by the formula (2) include methyl vinyl ether, ethyl vinyl ether, n-propyl vinyl ether, isopropyl vinyl ether, and n-butyl group. Vinyl ether, isobutyl vinyl ether, tert-butyl vinyl ether, n-hexyl vinyl ether, 2-ethylhexyl vinyl ether, n-octyl vinyl ether, n-decyl vinyl ether and rhodium An alkyl vinyl ether having an alkyl group having 1 to 10 carbon atoms such as a vinyl ether; an aromatic vinyl compound such as styrene, ethylene toluene or ethylene xylene; (Meth) acrylamide, ethyl (meth) acrylamide, n-propyl (meth) acrylamide, isopropyl (meth) acrylamide, n-butyl (meth) acrylamide And N-alkyl (meth) acrylamide such as 2-ethylhexyl (meth) acrylamide; methylaminopropyl (meth) acrylamide, dimethylaminopropyl (meth) propylene Indoleamine, ethylaminopropyl (meth) acrylamide and diethylaminopropyl (meth) acrylamide, etc. (B) alkylaminoalkyl hydrazines; methyl (meth) acrylate (ethyl)acrylic acid (di)alkylaminoalkane such as ethyl ester, dimethylaminoethyl (meth) acrylate, ethylaminoethyl (meth) acrylate and diethylaminoethyl (meth) acrylate For the esters, such as α-olefins such as ethylene, propylene, and butylene, one or more of these may be used.

Further, the monomer mixture may contain a monomer other than the monomer having a vinyl ester or a structural unit represented by the formula (2) within the range in which the effects of the present invention can be obtained. Specific examples of the compound include methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, and (meth)acrylic acid such as 2-ethylhexyl (meth)acrylate. Alkyl esters; unsaturated acids such as (meth)acrylic acid, crotonic acid, maleic acid, itaconic acid and fumaric acid, and alkyl esters thereof; unsaturated anhydrides such as maleic anhydride; 2-propene oxime A sulfonic acid group-containing monomer or the like such as amine-2-methylpropanesulfonic acid or a salt thereof.

The amount of such monomers in the water-soluble polymer is preferably in the range of 0 to 25 mol%, more preferably in the range of 0 to 15 mol%.

The aforementioned copolymerization method is not particularly limited, and a solution polymerization method is preferred. According to solution polymerization, a copolymer of the water-soluble polymer of the present invention can be obtained in a uniform solution.

The polymerization solvent at the time of solution polymerization may, for example, be an alcohol such as methanol or ethanol. One type of these may be used, or two or more types may be used in combination, such as ketones such as acetone and methyl ethyl ketone, and guanamines such as N,N-dimethylformamide. Among the above, methanol is preferably used from the viewpoint of directly using the polymer solution after polymerization for the saponification reaction described later.

Further, a known polymerization initiator can be used in the polymerization, but a radical polymerization initiator can be suitably used in particular.

Examples of the radical polymerization initiator include hydroperoxides such as sodium persulfate, potassium persulfate, and ammonium persulfate, hydroperoxides such as tertiary butyl hydroperoxide, and water-soluble such as hydrogen peroxide. Dialkyl peroxidation such as peroxide, methyl ethyl ketone peroxide, cyclohexanone peroxide and other ketone peroxides, di-tertiary butyl peroxide, tertiary butyl peroxy cumene Oil-soluble peroxides such as peroxy esters such as peroxyisobutyric acid tertiary butyl ester and peroxyisobutyric acid tertiary hexyl ester, 2,2'-azobisisobutyronitrile, 2,2' An azo compound such as azobis(2,4-dimethylvaleronitrile) or 2,2'-azobis(2-methylbutyronitrile).

The radical polymerization initiator may be used alone or in combination of two or more.

Among the above-mentioned radical polymerization initiators, persulfate or azo compounds are preferred, and azo compounds are particularly preferred because of the control viewpoint of facilitating the polymerization reaction.

The use ratio of the radical polymerization initiator is not particularly limited, but is preferably 0.1 to 10% by mass, more preferably 0.1 to 5% by mass based on the total weight of the total monomers constituting the entire water-soluble polymer. The ratio is preferably 0.2 to 3% by mass.

In the manufacture of the water-soluble polymer of the present invention, for adjustment The molecular weight may also be appropriately added to the polymerization system by a chain transfer agent. Examples of the chain transfer agent include indole acetic acid, mercaptopropionic acid, 2-propanethiol, and 2-indole ethanol.

The above-mentioned chain transfer agent may be used alone or in combination of two or more. When the chain transfer agent is used, it is preferably used in an amount of from 0.1 to 10% by mass, more preferably from 0.5 to 5% by mass, based on the total amount of the monomers.

The reaction temperature at the time of polymerization is preferably from 30 to 100 ° C, more preferably from 40 to 90 ° C, and still more preferably from 50 to 80 ° C.

After the above copolymerization, the obtained copolymer is saponified in an organic solvent in the presence of a catalyst. As the organic solvent (hereinafter referred to as a saponification solvent) used in the saponification step, an alcohol such as methanol, ethanol, propanol, ethylene glycol, propylene glycol, glycerin or diethylene glycol can be used, and methanol is preferred. .

Further, examples of the saponification catalyst include alkali catalysts such as sodium hydroxide, potassium hydroxide, sodium alcoholate, and sodium carbonate; and acid catalysts such as sulfuric acid, phosphoric acid, and hydrochloric acid. Among these saponification catalysts, an alkali catalyst is preferably used, and sodium hydroxide or potassium hydroxide is more preferably used. Thereby, the saponification speed can be accelerated and the productivity can be improved.

By saponification, a part or all of the vinyl ester unit in the copolymer is saponified to be converted into a vinyl alcohol unit. Further, the degree of saponification is not particularly limited, and may be appropriately set depending on the composition of the water-soluble polymer, etc., and is generally 70 to 99.9 mol%, preferably 80 to 99 mol%, more preferably 90 to 99 mol%.

The water-soluble polymer obtained by saponification can be used in the week It is known that the organic solvent, water, and the like are dried and removed, and the treatment is carried out in a solid state. After drying, it can also be pulverized and graded according to requirements.

Further, it is also possible to wash, for example, methyl acetate, methanol, water or the like as a cleaning liquid before drying to reduce salts or volatile components.

<Sweetener for Semiconductors>

The wetting agent for a semiconductor of the present invention comprises the above water-soluble polymer. In general, the wetting agent for semiconductors may contain water. Further, the wetting agent for semiconductor is preferably an aqueous solution in which a water-soluble polymer is dissolved in water. It is preferred to use water with higher purity to prevent damage and the effect as a wetting agent. Specifically, it is preferred to use pure water or ultrapure water or distilled water which removes impurities by removing ion ions with an ion exchange resin. In addition to the above, the wetting agent may include an organic solvent such as an alcohol or a ketone having high compatibility with water.

The ratio of the water-soluble polymer in the wetting agent for a semiconductor is not particularly limited as long as it is easy to handle the aqueous solution, and is preferably in the range of 1 to 50% by mass, more preferably 3 to 40% by mass. The range is preferably in the range of 5 to 30% by mass.

The water-soluble polymer of the present invention has excellent adsorptivity to the surface of the wafer or the like, and particularly exhibits high adsorptivity to the surface of the wafer in a state in which the oxide film is completely removed. Therefore, when the wetting agent for a semiconductor of the present invention is used in the surface treatment step of the wafer, the smoothness of the surface of the wafer after polishing can be improved, and contamination due to COP and particle adhesion can be reduced. For the reasons for these effects, the following mechanisms are assumed: The smoothness of the surface of the wafer is such that the water-soluble polymer in the semiconductor wetting agent is adsorbed on the surface of the wafer, so that the friction between the surface of the wafer and the abrasive grains can be alleviated during the mechanical polishing of the CMP; The fine unevenness formed on the surface of the wafer by mechanical polishing can be reduced, and the smoothness can be improved.

Further, as described above, in the mechanical polishing, the polishing composition is supplied to the surface of the wafer, and the polishing pad is pressed against the surface of the wafer to be rotated to physically polish the surface of the wafer. Therefore, on the wafer surface, the polishing pad is pressed against a portion other than the COP, and the wafer surface is polished in the vertical direction. As mechanical grinding progresses, the COP gradually decreases and the COP disappears when the wafer surface is ground to above its depth. Therefore, it is considered that mechanical grinding can show the effect of reducing the number of COPs and reducing their size.

On the other hand, in chemical polishing, a polishing composition is added to the COP during polishing to cause the alkaline compound to corrode or etch the inside of the COP. As described above, in the COP, since the polishing is performed in a direction perpendicular to the inner wall thereof, it is considered that the COP of the wafer surface increases as the chemical polishing progresses.

In the present invention, the water-soluble polymer adsorbed on the surface of the wafer is assumed to have a function of suppressing chemical polishing to a level higher than mechanical polishing. The higher the adsorptivity of the water-soluble polymer to the wafer, the stronger the tendency. As a result, it is estimated that a wafer surface having high smoothness and less COP can be obtained.

Further, by adsorbing the water-soluble polymer on the surface of the wafer, the surface thereof is hydrophilized. Thereby, it is also possible to prevent contamination due to adhesion of particles during polishing.

Further, according to the present invention, there is also provided a water-soluble solution A method in which a polymer is adsorbed on a wafer to polish a wafer. The form in which the water-soluble polymer is adsorbed on the wafer is included in the form of a wetting agent for a semiconductor containing a water-soluble polymer and water, and includes a water-soluble polymer, water, abrasive grains, and the like. A form in which a composition for polishing an alkali compound is supplied to a wafer.

<grinding composition>

The polishing composition of the present invention comprises the above-mentioned semiconductor wetting agent, water, abrasive grains, and an alkali compound. The ratio of the semiconductor wetting agent in the polishing composition is not particularly limited, and it is preferred to adjust the viscosity to a suitable viscosity when the polishing composition is subjected to CMP processing or adsorption to the wafer surface. The specific viscosity of the polishing composition is preferably 0.1 to 10 mPa. The range of s is more preferably 0.3~8mPa. The range of s is preferably 0.5~5mPa. The range of s.

In addition, the water-soluble polymer is preferably used in an amount of from 0.001 to 10% by mass based on the total amount of the composition for the polishing agent, and more preferably in the range of from 0.005 to 5% by mass.

As the abrasive grains, colloidal cerium oxide or the like can be used. When colloidal cerium oxide is used as the abrasive grains, the content in the polishing composition is preferably from 0.1 to 50% by mass, more preferably from 1 to 30% by mass, even more preferably from 3 to 20% by mass. When the amount of the colloidal cerium oxide is 0.1% by mass or more, the polishing rate of mechanical polishing is good. In addition, when it is 50% by mass or less, the dispersibility of the abrasive grains can be maintained, and the smoothness of the surface of the wafer can be further improved.

The average particle size of the colloidal cerium oxide can be determined by the required grinding speed The smoothness of the surface of the wafer after polishing is appropriately selected, and is generally in the range of 2 to 500 nm, preferably in the range of 5 to 300 nm, more preferably in the range of 5 to 200 nm.

The alkali compound is not particularly limited as long as it is a water-soluble alkali compound, and an alkali metal hydroxide, an amine or ammonia, or a quaternary ammonium hydroxide salt can be used. Examples of the alkali metal hydroxide include potassium hydroxide, sodium hydroxide, barium hydroxide, and barium hydroxide. Examples of the amines include triethylamine, monoethanolamine, diethanolamine, triethanolamine, diisopropanolamine, ethylenediamine, hexamethylenediamine, diethylenetriamine, triethylpentamine, and tetraethylpenta. Amines, etc. Examples of the fourth-order ammonium hydroxide salt include tetramethylammonium hydroxide, tetraethylammonium hydroxide, and tetrabutylammonium hydroxide. Among these, ammonia or a quaternary ammonium hydroxide salt is preferred from the viewpoint of less contamination of the semiconductor substrate.

The polishing composition of the present invention is preferably adjusted to have a pH of 8 to 13 by adding the above-mentioned alkali compound. The pH range is better adjusted to 8.5~12.

In addition to the above, in the composition for an abrasive, an organic solvent, various chelating agents, surfactants, and the like may be added as needed.

[Examples]

Hereinafter, the present invention will be specifically described based on examples. Moreover, the invention is not limited by such embodiments. In addition, the following "parts" and "%", if not specifically stated, refer to the parts by mass and mass%.

The analysis of the water-soluble polymer obtained in the production example is described below. A method for evaluating a semiconductor wetting agent or a polishing composition in the examples and the examples and the comparative examples.

<Saponification degree>

It is measured according to JIS K6726.

<Quantitative average molecular weight (Mn)>

The copolymer before saponification obtained in each of the production examples was measured by GPC (gel permeation chromatography instrument; HLC-8220, manufactured by TOSOH) in terms of polystyrene.

<etching resistance (E.R.)>

The weight of the wafer cut into 3 × 6 cm by a glass cutter was measured, and then immersed in a 3% hydrofluoric acid aqueous solution for 20 seconds to remove the oxide film on the surface of the wafer, followed by washing with pure water for 10 seconds. Repeat this step until the surface of the wafer is completely drained. Next, a wetting agent for a semiconductor was added to ammonia water having a weight ratio of ammonia:water of 1:19, and the concentration of the water-soluble polymer was made 0.18 wt% to prepare an etching solution. The wafer was completely immersed in an etching solution, and allowed to stand at 25 ° C for 12 hours for etching. The etching rate (E.R.) was calculated by the following equation from the change in wafer weight before and after etching.

<Wettability>

The oxide film on the surface of the wafer was removed in the same manner as the etching resistance, and then immersed in a 0.18 wt% water-soluble polymer solution for 5 minutes. After the immersion, the surface of the wafer was lifted perpendicularly to the liquid surface by using tweezers, and the water-repellent distance from the end of the wafer at the time of 10 seconds was visually confirmed, and the judgment was made based on the following criteria.

○: Water distance is less than 5mm

△: Water distance 5~10mm

×: water distance exceeds 10mm

<Wafer appearance>

The surface of the wafer after etching in the same manner as the etching resistance was visually confirmed and judged based on the following criteria.

○: No cracks were observed on the surface

△: The surface is slightly cleft

×: The surface is significantly cleaved

<Alkaline resistance>

In a 50 cc screw cap vial, 5.0 g of a water-soluble polymer was added to 40 g of an aqueous alkali solution of pH 10 prepared by dissolving sodium hydroxide in water, and the cap was capped and thoroughly mixed. The hydrolysis rate after standing at 50 ° C for one month in an aluminum block heater was evaluated by GC (gas chromatograph; GC-2014, manufactured by Shimadzu Corporation), and was determined based on the following criteria.

○: The hydrolysis rate of the water-soluble polymer is less than 1%

△: The hydrolyzed substance of the water-soluble polymer is 1% or more and less than 5%

×: The hydrolysis rate of the water-soluble polymer is 5% or more

<Oxide dispersibility>

In a 9 cc screw cap vial, 5.0 g of a colloidal cerium oxide (primary particle diameter: 30 to 50 nm) was added with 0.5 g of a water-soluble polymer aqueous solution having a resin solid content of 20%, and sufficiently mixed. The particle size (A) of the cerium oxide after standing overnight was measured by a dynamic light scattering method (ELSZ-1000, manufactured by Otsuka Electronics Co., Ltd.), and the particle size of the colloidal cerium oxide not added with the water-soluble polymer was calculated by the following formula (B). The rate of change of the phase difference is determined based on the following criteria.

Rate of change (%) = {(A-B) / B} × 100

○: The rate of change is less than 10%

△: The rate of change is more than 10% - less than 30%

×: The rate of change is 30% or more

Manufacturing example 1 Synthesis of Copolymer of Ethyl Acetate and Alkyl Vinyl Ether Copolymer

A three-liter three-necked flask equipped with a stirring blade, a reflux cooling tube, a thermometer, and various introduction tubes was prepared, and 375 parts of vinyl acetate (manufactured by JAPAN VAM & POVAL Co., Ltd., hereinafter referred to as "VAc") and 250 as an initial monomer were fed. N-propyl vinyl ether (made by NIPPON CARBIDE, Hereinafter, "NPVE" is used, and 250 parts of methanol as a polymerization solvent are stirred and mixed. Further, while the nitrogen gas was blown through a nitrogen gas introduction tube at a flow rate of 10 ml/min, the temperature of the mixture was raised to 60 ° C in 40 minutes.

After confirming the temperature rise, an initial addition of 2.0 parts of 2,2-azobis-2,4-dimethylvaleronitrile (manufactured by Wako Pure Chemical Industries, Ltd., trade name "V-65") in 50 parts of methanol was added. The solution of the initiator is initiated and polymerized.

At the same time as the start of the polymerization, 450 parts of the Vac as a dropping monomer was polymerized by dropping the monomer into the tube for 6 hours. On the other hand, a chain transfer agent solution obtained by dissolving 4.0 parts of 2-indole ethanol (hereinafter referred to as "MTG") in 150 parts of methanol, and a dropping of 8.0 parts of V-65 in 120 parts of methanol were started. The solution of the agent was also dropped by each introduction tube for 6 hours simultaneously with the start of polymerization.

After allowing to polymerize for 6 hours, the flask was cooled to room temperature, and 0.3 part of 4-methoxyphenol was added to terminate the polymerization to obtain a copolymer 1A. The copolymer 1A had a number average molecular weight Mn of 10,000 and a polymerization yield of 85%. The residual single system contained in the copolymer 1A was removed together with methanol by a vacuum pump attached to a flask and heated under reduced pressure at 50 °C.

Synthesis of ≪Water Soluble Polymer (Saponification of Copolymer)≫

The saponification reaction was carried out without withdrawing the copolymer 1A from the flask. The mixture was heated to 60 ° C for 30 minutes while blowing nitrogen gas through a nitrogen gas introduction tube at a flow rate of 10 ml/min. After confirming the temperature rise, an alkali solution obtained by dissolving 3.9 parts of sodium hydroxide in 75 parts of methanol 7 was integrally added to initiate a saponification reaction. After 4 hours, the temperature was lowered to stop the reaction. Rotate the solvent After the evaporator was removed, it was vacuum dried at 60 ° C overnight to obtain a water-soluble polymer 1B as a tan solid.

As a result of measuring the composition of the water-soluble polymer 1B by ¹ H-NMR, it was a copolymer of polyvinyl alcohol / NPVE = 77 / 23 mol%, and the saponification ratio was 98.0 mol%.

Manufacturing Example 2

In the same manner as in Production Example 1, the copolymer 2A was obtained in the same manner except that the amount of MTG used was changed to 10.0 parts. The copolymer 2A had a molecular weight of Mn = 2,200 and a polymerization yield of 78%.

The copolymer 2A was saponified in the same manner as in Production Example 1 to obtain a water-soluble polymer 2B. As a result of measuring the composition of the water-soluble polymer 2B, it was a copolymer of polyvinyl alcohol/NPVE = 77 / 23 mol%, and the saponification ratio was 98.0 mol%.

Manufacturing Example 3

In the same manner as in the monomer used in Production Example 1, the copolymer 3A was obtained in the same manner except that the initial monomer was changed to 480 parts of VAc, 200 parts of NPVE, and the monomer to be dropped was changed to 320 parts of VAc. The copolymer 3A had a molecular weight of Mn = 11,000 and a polymerization yield of 83%.

The copolymer 3A was saponified in the same manner as in Production Example 1 to obtain a water-soluble polymer 3B. As a result of measuring the composition of the water-soluble polymer 3B, it was a copolymer of polyvinyl alcohol/NPVE = 84/16 mol%, and the saponification ratio was 98.4 mol%.

Manufacturing Example 4

In the same manner as in the monomer used in Production Example 1, the copolymer 4A was obtained in the same manner except that the initial monomer was changed to 720 parts of Vac, 100 parts of NPVE, and the monomer to be dropped was changed to 180 parts of Vac. The copolymer 4A had a molecular weight of Mn = 10,000 and a polymerization yield of 81%.

The copolymer 4A was saponified in the same manner as in Production Example 1 to obtain a water-soluble polymer 4B. As a result of measuring the composition of the water-soluble polymer 4B, it was a copolymer of polyvinyl alcohol/NPVE=91/9 mol%, and the saponification ratio was 98.0 mol%.

Manufacturing Example 5

In the same manner as in the production example 4, the copolymer 5A was obtained in the same manner except that the NPVE was changed to 100 parts of n-butyl vinyl ether (hereinafter referred to as "NBVE" manufactured by NIPPON CARBIDE Co., Ltd.). The copolymer 5A had a molecular weight of Mn = 9,000 and a polymerization yield of 80%.

The copolymer 5A was saponified in the same manner as in Production Example 1 to obtain a water-soluble polymer 5B. As a result of measuring the composition of the water-soluble polymer 5B, it was a copolymer of polyvinyl alcohol/NBVE = 90/10 mol%, and the saponification ratio was 98.1 mol%.

Manufacturing Example 6

In addition to the monomers used in Production Example 1, the initial monomer was changed to VAc 475 parts, 2-ethylhexyl vinyl ether (NIPPON CARBIDE) Copolymer 6A was obtained in the same manner except that 50 parts of the company's product, hereinafter referred to as "EHVE", and a dropping monomer were changed to Vac 475 parts. The copolymer 6A had a molecular weight of Mn of 8,000 and a polymerization yield of 75%.

The copolymer 6A was saponified in the same manner as in Production Example 1 to obtain a water-soluble polymer 6B. As a result of measuring the composition of the water-soluble polymer 6B, it was a copolymer of polyvinyl alcohol/EHVE = 97/3 mol%, and the saponification ratio was 99.0 mol%.

Manufacturing Example 7

In the same manner as in the production example 4, the chain transfer agent was not dropped, and 0.4 parts of the initial initiator and 1.6 parts of the starting agent were added, and the solvent was changed to the third-stage butanol to carry out the same operation to obtain the copolymer 7A. . The copolymer 7A had a molecular weight of Mn = 170,000 and a polymerization yield of 69%.

The copolymer 7A was saponified in the same manner as in Production Example 1 to obtain a water-soluble polymer 7B. As a result of measuring the composition of the water-soluble polymer 7B, it was a copolymer of polyvinyl alcohol/NPVE = 91 / 9 mol%, and the saponification ratio was 98.1 mol%.

Manufacturing Example 8

The copolymer 8A was obtained by the same operation except that the initial initiator was changed to 0.2 part in Production Example 7, and the dropping initiator was changed to 0.8 part. The copolymer 8A had a molecular weight of Mn = 220,000 and a polymerization yield of 52%.

The copolymer 8A was saponified in the same manner as in Production Example 1 to obtain water. Soluble polymer 8B. As a result of measuring the composition of the water-soluble polymer 8B, it was a copolymer of polyvinyl alcohol / NPVE = 91 / 9 mol%, and the saponification ratio was 98.1 mol%.

Manufacturing Example 9

A 3 L four-necked flask equipped with a stirring blade, a reflux cooling tube, a thermometer, and various introduction tubes was fed with 475 parts of VAc and 25 parts of N,N-diisopropylpropene decylamine (hereinafter referred to as "NIPAM". Further, 1150 parts of N,N-dimethylformamide (hereinafter referred to as "DMF") as a polymerization solvent were stirred and mixed. Further, while the nitrogen gas was blown through a nitrogen gas introduction tube at a flow rate of 10 ml/min, the temperature of the mixture was raised to 60 ° C in 40 minutes.

After confirming the temperature rise, a starter solution in which 0.5 part of V-65 was dissolved in 50 parts of DMF was added in one piece to initiate polymerization.

After allowing to polymerize for 1 hour, the flask was cooled to room temperature, and 0.18 part of 4-methoxyphenol was added to terminate the polymerization to obtain a copolymer 9A. The copolymer 9A had a molecular weight of Mn = 16,000 and a polymerization yield of 17%. The solvent and residual single system contained in the copolymer 9A were removed by a rotary evaporator and then removed by vacuum drying at 80 ° C overnight.

The copolymer 9A was saponified in the same manner as in Production Example 1 to obtain a water-soluble polymer 9B. As a result of measuring the composition of the water-soluble polymer 9B, it was a copolymer of polyvinyl alcohol/NIPAM=75/25 mol%, and the saponification ratio was 98.3 mol%.

Manufacturing Example 10

500 parts of methanol, 180 parts of VAc, and 0.2 part of V-65 were added to an autoclave equipped with a pressure regulating valve, and thoroughly mixed. Next, after the nitrogen in the autoclave was replaced by blowing nitrogen gas, ethylene was injected through a pressure regulating valve. In the face of stirring in the autoclave, the temperature was raised to 60 ° C to carry out polymerization.

While maintaining the ethylene pressure during the polymerization at 30 kg/cm ^{2 for} 3 hours, the autoclave was cooled to room temperature. Next, 0.1 part of 4-methoxyphenol was added to terminate the polymerization to obtain a copolymer 10A. The copolymer 10A had a molecular weight of Mn = 15,000 and a polymerization yield of 63%. The solvent and residual single system contained in the copolymer 9A were removed by vacuum drying at 80 ° C overnight.

The copolymer 10A was saponified in the same manner as in Production Example 1 to obtain a water-soluble polymer 10B. As a result of measuring the composition of the water-soluble polymer 10B, it was a copolymer of polyvinyl alcohol/ethylene = 92/8 mol%, and the saponification ratio was 98.5 mol%.

Manufacturing Example 11

In the same manner as in the case of the monomer used in Production Example 1, the copolymer 11A was obtained in the same manner except that the initial monomer was changed to 227.5 parts of Vac, 350 parts of NPVE, and 42.5% of the dropping monomer was changed to Vac. The copolymer 11A had a molecular weight Mn of 10,000 and a polymerization yield of 70%.

The copolymer 11A was saponified in the same manner as in Production Example 1 to obtain a polymer 11B. As a result of measuring the composition of the polymer 11B, it was a copolymer of polyvinyl alcohol/NPVE = 65/35 mol%, and the saponification ratio was 98.5 mol%.

Manufacturing Example 12

In addition to the monomers used in Production Example 1, the initial monomer was changed to 475 parts of Vac, n-dodecyl vinyl ether (hereinafter referred to as "NDVE" by BASF Corporation), and 50 parts of the monomer was changed to Vac475. Polymer 12A was obtained in the same manner except for the portion. The polymer 12A had a molecular weight of Mn = 10,000 and a polymerization yield of 90%.

The polymer 12A was saponified in the same manner as in Production Example 1 to obtain a polymer 12B. The saponification ratio of the polymer 12B was 97.5 mol%.

Manufacturing Example 13

In the same manner as in Production Example 9, the copolymer 13A was obtained in the same manner except that the monomer to be used was changed to 440 parts of VAc and 60 parts of NIPAM. The copolymer 13A had a molecular weight of Mn = 10,000 and a polymerization yield of 24%.

The copolymer 13A was saponified in the same manner as in Production Example 1 to obtain a water-soluble polymer 13B. As a result of measuring the composition of the water-soluble polymer 13B, it was a copolymer of polyvinyl alcohol/NIPAM = 50/50 mol%, and the saponification ratio was 98.0 mol%.

Example 1

Water was added to adjust the concentration of the water-soluble polymer 1B to 15% by mass to prepare a wetting agent for a semiconductor. The obtained semiconductor wetting agent was evaluated for etching resistance, wettability, wafer appearance, and alkali resistance. The results obtained are shown in Table 1.

In addition, 10.0 g of colloid added with ammonia water to adjust the pH to 10.0 was added. The cerium oxide dispersion (primary particle system 30 to 50 nm, cerium oxide solid content: 10%) and 0.1 g of the above-mentioned semiconductor wetting agent were used to obtain a composition for an abrasive. The obtained abrasive composition was evaluated for cerium oxide dispersibility, and Table 1 shows the results.

Examples 2 to 10 and Comparative Examples 1 to 7

A wetting agent for a semiconductor and an abrasive composition were prepared in the same manner as in Example 1 except that the water-soluble polymer shown in Table 1 was used. However, in Comparative Examples 1 and 2, some or most of the polymer after saponification was insoluble in water, and evaluation as a wetting agent and an abrasive composition could not be performed. The evaluation results of the respective samples are shown in Table 1.

The details of the water-soluble polymer shown in Table 1 are as follows: PVA105: completely saponified polyvinyl alcohol (manufactured by KURARAY, trade name "KURARAY POVAL PVA105", saponification degree: 98.5 mol%, polymerization degree: 500)

PVA505: low saponified polyvinyl alcohol (KURARAY POVAL PVA505, manufactured by KURARAY Co., Ltd., saponification degree: 73.5 mol%, polymerization degree: 500)

HEC: hydroxyethyl cellulose (manufactured by Wako Pure Chemical Industries, Ltd., weight average molecular weight 90,000)

PVP K30: Polyvinylpyrrolidone (manufactured by Tokyo Chemical Industry Co., Ltd.)

Examples 1 to 10 are experimental examples using the water-soluble polymer defined by the present invention, and since the adsorptivity to the wafer is high, the etching resistance, the wettability, and the appearance of the wafer are excellent. Moreover, it was confirmed that the cerium oxide dispersibility at the time of preparation of the abrasive composition was also excellent.

On the other hand, Comparative Example 4 using a water-soluble polymer having no structural unit represented by the formula (2) has insufficient adsorptivity to the surface of the wafer, and is excellent in etching resistance, wettability, and wafer appearance. Poor results. Further, in Comparative Example 5 in which polyvinyl alcohol having a low saponification ratio was used, hydrolysis of a unit derived from vinyl acetate occurred, and alkali resistance was insufficient. Comparative Examples 6 and 7 using a water-soluble polymer having a structural unit different from the water-soluble polymer of the present invention were not satisfied in terms of adsorption to the surface of the wafer and dispersibility of cerium oxide.

Further, as described above, in Comparative Examples 1 and 2, since the polymer after saponification is insoluble in water, it cannot be used as a wetting agent and an abrasive composition. Assessment. In Comparative Example 1, it is considered that the structural unit represented by the formula (2) is excessively large, and the solubility of the polymer obtained after saponification in water is insufficient. In Comparative Example 2, it is presumed that the copolymerization of vinyl acetate and n-dodecyl vinyl ether is poor, and a water-insoluble polymer component containing n-dodecyl vinyl ether as a main component is formed. To.

[Industrial availability]

The wetting agent for a semiconductor of the present invention is excellent in the adsorptivity to the surface of the wafer after polishing, and by using the polishing composition containing the wetting agent for the semiconductor, the smoothness of the surface of the wafer after polishing can be improved. Inhibition of COP. Further, since the dispersibility of cerium oxide is also good, it is particularly useful as a final polishing composition for a ruthenium wafer.

Claims (7)

A wetting agent for a semiconductor comprising a water-soluble polymer having 70 to 99 mol% of a structural unit represented by the formula (1) and 1 to 30 mol% of a structural unit represented by the formula (2); CH ₂ CH(OH)-] (1) [-CH ₂ CH(X)-] (2) In the formula (2), X represents an alkyl ether group having an alkyl group having 1 to 10 carbon atoms, and a carbon number of 6 An aryl group of ~10, an organic group represented by the formula (3) or the formula (4), a urethane alkyl group having an alkyl group having 1 to 10 carbon atoms, a ring having an alkyl group having 3 or more carbon atoms An oxyalkyl group, a hydrogen or an alkyl group having 1 to 3 carbon atoms; -C(=O)O-(CH ₂ ) _m -R ¹ (3) In the formula (3), R ¹ represents an alkane having 1 to 8 carbon atoms An alkylamino group or a dialkylamino group having an alkyl group having 1 to 4 carbon atoms, m represents an integer of 0 to 3; -C(=O)O-(CH ₂ ) _m -R ¹ (3) In 4), R ² represents an alkyl group having 1 to 8 carbon atoms, an alkylamino group or a dialkylamino group having an alkyl group having 1 to 4 carbon atoms, and n represents an integer of 0 to 3. The wetting agent for a semiconductor according to claim 1, wherein the water-soluble polymer is obtained by copolymerizing vinyl acetate and another vinyl monomer, followed by saponification. The wetting agent for a semiconductor according to claim 1 or 2, wherein the water-soluble polymer has a number average molecular weight of 1,000 to 200,000. A polishing composition comprising the semiconductor wetting agent, water, abrasive grains, and an alkali compound according to any one of claims 1 to 3. The polishing composition of claim 4, wherein the abrasive particles are colloidal cerium oxide. The polishing composition of claim 4 or 5, which is the final abrasive user of the wafer. A method for polishing a tantalum wafer using a water-soluble polymer having 70 to 99 mol% of a structural unit represented by the formula (1) and 1 to 30 mol% of a structural unit represented by the formula (2) in a molecule Grinding the crucible wafer; [-CH ₂ CH(OH)-] (1) [-CH ₂ CH(X)-] (2) In the formula (2), X represents an alkyl group having 1 to 10 carbon atoms. An alkyl ether group, an aryl group having 6 to 10 carbon atoms, an organic group represented by the formula (3) or the formula (4), a urethane group having an alkyl group having 1 to 10 carbon atoms, having a carbon number An alkylene group having 3 or more alkylene groups, hydrogen or an alkyl group having 1 to 3 carbon atoms; -C(=O)O-(CH ₂ ) _m -R ¹ (3) In the formula (3), R ¹ An alkyl group having 1 to 8 carbon atoms, an alkylamino group or a dialkylamino group having an alkyl group having 1 to 4 carbon atoms, and m is an integer of 0 to 3; -C(=O)NH-(CH ₂ ) _n -R ² (4) In the formula (4), R ² represents an alkyl group having 1 to 8 carbon atoms, an alkylamino group or a dialkylamino group having an alkyl group having 1 to 4 carbon atoms, and n represents an integer of 0 to 3 .